JP2021191841A - Rubber composition and molded product - Google Patents

Abstract

To provide a rubber composition as a rubber composition containing fine fibrous cellulose and rubber components, capable of molding a molded product which has excellent designability and is suppressed in coloring.SOLUTION: A rubber composition contains rubber components and fibrous cellulose. The rubber composition is such that: a substituent introduction amount in the fibrous cellulose is less than 0.5 mmol/g; and an average fiber width of the fibrous cellulose contained in the rubber composition is 1-100 nm.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition and a molded product.

In recent years, due to the substitution of petroleum resources and increasing environmental awareness, materials using reproducible natural fibers have been attracting attention. Among natural fibers, fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, particularly fibrous cellulose (pulp) derived from wood, has been widely used mainly as paper products.

As the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Fine fibrous cellulose is attracting attention as a new material, and its uses are wide-ranging. For example, sheets containing fine fibrous cellulose, resin complexes, and thickeners are being developed. It is also being studied to mix fine fibrous cellulose with a rubber component to form a rubber composition.

For example, Patent Document 1 contains a rubber component and a rubber composition containing microfibrillated plant fibers having an average fiber length of 1 to 20 μm, an average fiber diameter of 10 μm or less, and an aspect ratio of 2 to 1000. Is disclosed. Further, Patent Document 2 discloses a method for producing cellulose zantate nanofibers, which comprises defibrating a cellulose zantate or a cationic substituent of cellulose zantate. Patent Document 2 discloses an example in which a rubber sheet is produced by mixing cellulose zantate nanofibers with a natural rubber latex.

Japanese Unexamined Patent Publication No. 2011-231208 International Publication No. 2017/111033

While conducting research on a rubber composition containing fine fibrous cellulose and a rubber component, the present inventors may deteriorate the design or cause coloring in a molded product formed from such a rubber composition. I found out that there are cases.

Therefore, in order to solve the problems of the prior art, the present inventors have a rubber composition containing fine fibrous cellulose and a rubber component, which has excellent designability and suppression of coloring. We proceeded with the study for the purpose of providing a rubber composition capable of molding a rubber molded body.

As a result of diligent studies to solve the above problems, the present inventors have reduced the amount of substituents introduced in the fibrous cellulose to 0.5 mmol / g in the rubber composition containing the rubber component and the fibrous cellulose. It has been found that a rubber molded product having excellent designability and suppressed coloring can be obtained by setting the number to less than or equal to 1 to 100 nm and setting the number average fiber width of the fibrous cellulose contained in the rubber composition to 1 to 100 nm. rice field.
Specifically, the present invention has the following configurations.

[1] A rubber composition containing a rubber component and fibrous cellulose.
The amount of substituent introduced in the fibrous cellulose is less than 0.5 mmol / g, and the amount is less than 0.5 mmol / g.
A rubber composition having an average fiber width of 1 to 100 nm of fibrous cellulose contained in the rubber composition.
[2] The rubber composition according to [1], wherein the rubber composition is a kneaded product containing a rubber component and fibrous cellulose.
[3] The rubber composition according to [1] or [2], wherein the substituent is an anionic group.
[4] At least the anionic group is selected from the group consisting of a phosphoric acid group, a substituent derived from a phosphoric acid group, a sulfone group, a substituent derived from a sulfone group, a carboxy group and a substituent derived from a carboxy group. The rubber composition according to [3], which is one type.
[5] The rubber composition according to [3] or [4], wherein the anionic group is a phosphoric acid group or a substituent derived from a phosphoric acid group.
[6] The rubber composition according to any one of [1] to [5], wherein the fibrous cellulose has a carbamide group.
[7] The rubber component is at least one pre-crosslinked rubber selected from the group consisting of natural rubber, ethylene-propylene-diene copolymer rubber, silicone rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber and butadiene rubber. The rubber composition according to any one of [1] to [6], which is a raw material.
[8] A molded product obtained by molding the rubber composition according to any one of [1] to [7].

According to the present invention, it is possible to obtain a rubber composition having excellent designability and capable of molding a rubber molded body in which coloring is suppressed.

FIG. 1 is a graph showing the relationship between the amount of NaOH titrated and pH with respect to a fibrous cellulose-containing slurry having a phosphoric acid group. FIG. 2 is a graph showing the relationship between the amount of NaOH dropped and the pH with respect to the fibrous cellulose-containing slurry having a carboxy group.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

(Rubber composition)
The present invention relates to a rubber composition containing a rubber component and fibrous cellulose. Here, the amount of the substituent introduced in the fibrous cellulose is less than 0.5 mmol / g, and the number average fiber width of the fibrous cellulose contained in the rubber composition is 1 to 100 nm.

Conventionally, in order to obtain a molded product having excellent designability, it has been studied to obtain fine fibrous cellulose having a small fiber width by introducing a substituent into the fine fibrous cellulose or increasing the amount of the substituent introduced. Was there. However, when fine fibrous cellulose having a high substituent amount is blended in the rubber composition, the affinity with the rubber component becomes insufficient, the design is rather deteriorated, and the rubber composition is heated in the manufacturing process and the usage environment. As a result, the molded product may be colored. On the other hand, when the substituent introduction step was controlled to keep the amount of the substituent introduced low, the defibration of the fine fibrous cellulose was insufficient, and it was difficult to obtain a molded product having excellent design. Therefore, the present inventors have repeatedly studied the manufacturing process of fine fibrous cellulose, and the number average fiber width has been increased even though the amount of substituents introduced is as low as less than 0.5 mmol / g. We succeeded in obtaining fine fibrous cellulose having a diameter of 1 to 100 nm. Then, by molding a molded body from a rubber composition containing fine fibrous cellulose having a low substituent amount and a number average fiber width of 1 to 100 nm, molding with excellent designability and suppressed coloring is performed. I found that I could get a body.

The rubber composition of the present invention preferably contains a rubber component and fibrous cellulose, and the rubber composition may be a kneaded product containing a rubber component and fibrous cellulose. Even when the rubber composition is a kneaded product containing a rubber component and fibrous cellulose, the amount of substituents introduced in the fibrous cellulose is less than 0.5 mmol / g, and the number of fibrous celluloses contained in the kneaded product. The average fiber width is 1 to 100 nm. In the present invention, since the amount of the substituent introduced in the fibrous cellulose is less than 0.5 mmol / g, the fibrous cellulose is easily dispersed uniformly in the rubber component. Therefore, a homogeneous kneaded product can be obtained. Further, since the number average fiber width of the fibrous cellulose contained in the kneaded product is 1 to 100 nm, the kneaded product is excellent in designability. Therefore, the molded product formed from such a kneaded product also has excellent designability.

Here, the designability of the molded body can be evaluated by visually observing the molded body (rubber sheet) molded from the rubber composition and measuring the number of lumps having a diameter equivalent to an area circle of 1 mm or more. For example, the number of lumps having an area circle equivalent diameter of 1 mm or more in a sheet-shaped molded body (rubber sheet) having a size of 50 mm × 50 mm is preferably 30 or less, more preferably 20 or less. It is more preferably 10 or less. If the number of lumps having an area equivalent circle diameter of 1 mm or more in the sheet-shaped molded body having a size of 50 mm × 50 mm is within the above range, it can be determined that the molded body molded from the rubber composition has good design.

In this embodiment, the YI value of the molded product molded from the rubber composition is preferably 20 or less, more preferably 10 or less, still more preferably 5 or less. The lower limit of the YI value of the molded product is not particularly limited, but is preferably 0.1 or more. Here, the YI value of the molded product is a YI value measured in accordance with JIS K 7373: 2006. As the YI value measuring device, for example, Color Cutei (manufactured by Suga Test Instruments Co., Ltd.) can be used.

The YI change rate calculated from the following formula is preferably less than 240%, more preferably less than 160%, and even more preferably less than 80%.
YI change rate (%) = (yellowness of the molded body-yellowness of the molded body of the rubber component alone) / yellowness of the molded body of the rubber component alone x 100
Here, the yellowness of the molded body of the rubber component alone is the yellowness of the molded body formed from the rubber component obtained by removing the fibrous cellulose from the rubber composition. When calculating the YI change rate, a molded body obtained by heat-press molding the rubber component constituting the rubber composition by itself and a molded body having the same thickness are prepared and measured. In the present invention, if the rate of change in YI is within the above range, it can be determined that the coloring of the molded product molded from the rubber composition is suppressed.

Further, since the rubber composition of the present invention has the above-mentioned structure, it is possible to mold a molded product having excellent tensile properties. Conventionally, when fine fibrous cellulose is mixed with a rubber component, it has been difficult to uniformly disperse the fine fibrous cellulose in the rubber component, so that a rubber sheet containing fine fibrous cellulose tends to have inferior breaking stress and the like. Was being done. However, in the present invention, the amount of the substituent of the fine fibrous cellulose mixed with the rubber component is set to less than 0.5 mmol / g, and the average fiber width of the fine fibrous cellulose is set to 1 to 100 nm to make the rubber. The dispersibility of the fine fibrous cellulose in the components can be enhanced, thereby increasing the breaking stress of the rubber sheet formed from the rubber composition.

Here, the tensile properties of the rubber sheet (molded body) molded from the rubber composition can be evaluated by, for example, the tensile strength index. The tensile strength index is an index calculated by the following formula.
Tensile strength index = breaking stress of rubber sheet / breaking stress of control rubber sheet x 100
The breaking stress of the rubber sheet was measured by performing a tensile test in accordance with JIS K 6251: 2017 "Vulcanized rubber and thermoplastic rubber-How to determine tensile properties". Further, in the present specification, the control rubber sheet is a sheet formed from a single rubber component constituting the rubber composition.
The tensile strength index of the rubber sheet is preferably 100 or more, more preferably 110 or more, and even more preferably 120 or more. In the present invention, if the tensile strength index of the rubber sheet is within the above range, it can be determined that the tensile properties of the molded product molded from the rubber composition are good.

In the present embodiment, the rubber composition is preferably a kneaded product, but a sheet made of fibrous cellulose or the like may be impregnated with a rubber component. When the rubber composition is a kneaded product, the kneaded product may be a liquid material or a solid material. Examples of the solid substance include pellet-like, sheet-like, flake-like, and filament-like shapes.

In the present embodiment, when the rubber composition is a kneaded product, it is preferable that the fibrous cellulose is uniformly dispersed in the rubber composition. The state in which the fibrous cellulose is uniformly dispersed means that the content of the fibrous cellulose at any 10 points in the rubber composition is within the range of an average value of ± 10% by mass.

(Rubber component)
Examples of the rubber component contained in the rubber composition include synthetic rubber and natural rubber. The synthetic rubber or natural rubber may be a rubber having a crosslinked structure. Further, the rubber component includes a pre-crosslinking raw material such as raw rubber, latex or rubber solution used for forming solid rubber such as synthetic rubber and natural rubber (a raw material in which a cross-linking structure is not substantially formed, and the cross-linking agent is sulfur. In the case of, a raw material in which a crosslinked structure by vulture is not substantially formed) is also included.

Examples of the synthetic rubber include diene-based rubber. Examples of the diene rubber include butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber (IR), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), and acrylonitrile-styrene-butadiene copolymer. Examples include rubber, chloroprene rubber, styrene-isoprene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene and the like. .. Examples of synthetic rubber include ethylene-propylene copolymer rubber, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluororubber, and urethane rubber. Examples of natural rubber include modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber, and deproteinized natural rubber, in addition to natural rubber (NR). These rubber components may be used alone or in combination of two or more. Further, these rubber components may be pre-crosslinking raw materials having no cross-linking structure, or may have a cross-linking structure.

Among them, the rubber component may be at least one selected from the group consisting of natural rubber, ethylene-propylene-diene copolymer rubber, silicone rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber and butadiene rubber. preferable. Further, the rubber component may be a raw material before cross-linking. For example, the rubber component may be natural rubber, ethylene-propylene-diene copolymer rubber, silicone rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber and butadiene rubber. It is preferable that it is at least one kind of pre-cross-linking raw material selected from the group consisting of. When the rubber component is a pre-crosslinking raw material, the rubber component is preferably a latex of these rubbers. By using the above-mentioned rubber component as the rubber component, it becomes easy to obtain a molded product having more excellent design and suppressed coloring. Further, by using the rubber component as the rubber component, it becomes easy to obtain a molded product having excellent tensile properties.

The content of the rubber component in the rubber composition is preferably 50% by mass or more, more preferably 65% by mass or more, and more preferably 80% by mass or more, based on the total mass of the rubber composition. More preferred. The content of the rubber component is preferably 99.99% by mass or less, more preferably 99.5% by mass or less, and 99.0% by mass or less with respect to the total mass of the rubber composition. Is more preferable. The above content is the solid content of the rubber component contained in the rubber composition. By setting the content of the rubber component within the above range, it becomes easy to obtain a molded product having excellent designability and suppressed coloring. Further, by setting the content of the rubber component within the above range, it becomes easy to obtain a molded product having excellent tensile properties.

(Fibrous cellulose)
The rubber composition of the present invention contains fibrous cellulose having a substituent introduction amount of less than 0.5 mmol / g. The number average fiber width of the fibrous cellulose contained in the rubber composition is 1 to 100 nm. Usually, fibrous cellulose having a fiber width of 1000 nm or less is also referred to as fine fibrous cellulose or CNF. The fibrous cellulose contained in the rubber composition of the present invention is fine fibrous cellulose.

In the present embodiment, the amount of substituents introduced in the fine fibrous cellulose may be less than 0.5 mmol / g, preferably 0.4 mmol / g or less, and more preferably 0.3 mmol / g or less. It is more preferably 0.2 mmol / g or less, and particularly preferably 0.15 mmol / g or less. The amount of the substituent introduced in the fine fibrous cellulose may be 0.0 mmol / g, but is preferably 0.03 mmol / g or more, more preferably 0.04 mmol / g or more. It is more preferably 0.07 mmol / g or more. The fine fibrous cellulose used in the present invention is preferably fine fibrous cellulose obtained by removing the substituent so as to have the above-mentioned amount of the substituent introduced. In addition, in this specification, such a fine fibrous cellulose is also referred to as a substituent-removed fine fibrous cellulose.

The number average fiber width of the fine fibrous cellulose contained in the rubber composition may be 1 to 100 nm, preferably 1 to 50 nm, more preferably 1 to 40 nm, and 1 to 30 nm. It is more preferably 1 to 20 nm, more preferably 1 to 10 mm, and particularly preferably 1 to 10 mm.

The fiber width of the fine fibrous cellulose is measured as follows, for example, using electron microscopy. First, the fine fibrous cellulose is dispersed in water so that the concentration of the cellulose is 0.01% by mass or more and 0.1% by mass or less, and cast on a hydrophilized carbon film-coated grid. After drying this, it is stained with uranyl acetate and observed with a transmission electron microscope (TEM, manufactured by JEOL Ltd., JEOL-2000EX). At that time, an axis having an arbitrary vertical and horizontal image width is assumed in the obtained image, and the magnification is adjusted so that 20 or more fibers intersect the axis. After obtaining an observation image satisfying this condition, two random axes in each of the vertical and horizontal directions are drawn with respect to this image, and the fiber width of the fiber intersecting the axis is visually read. In this way, three non-overlapping observation images are taken, and the value of the fiber width of the fiber intersecting each of the two axes is read (20 or more × 2 × 3 = 120 or more).
(1) A straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The number average fiber width of the fine fibrous cellulose contained in the rubber composition is a number average value calculated from the fiber width obtained by the above method.

The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and 0.1 μm or more and 600 μm or less. More preferred. By setting the fiber length within the above range, it is possible to suppress the destruction of the crystal region of the fine fibrous cellulose. Further, it is possible to set the slurry viscosity of the fine fibrous cellulose in an appropriate range. The fiber length of the fine fibrous cellulose can be obtained by, for example, image analysis by TEM, SEM, or AFM.

The fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has an I-type crystal structure can be identified in the diffraction profile obtained from the wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatic with graphite. Specifically, it can be identified by having typical peaks at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. The ratio of the type I crystal structure to the fine fibrous cellulose is, for example, preferably 30% or more, more preferably 40% or more, still more preferably 50% or more. The crystallinity is determined by a conventional method from the X-ray diffraction profile measured and the pattern (Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

The axial ratio (fiber length / fiber width) of the fine fibrous cellulose is not particularly limited, but is preferably 20 or more and 10000 or less, and more preferably 50 or more and 1000 or less. By setting the axial ratio to the above lower limit value or more, it is easy to form a sheet containing fine fibrous cellulose. By setting the axial ratio to the above upper limit value or less, it is preferable in that handling such as dilution becomes easy when, for example, fibrous cellulose is treated as a dispersion liquid.

The fine fibrous cellulose in the present embodiment has, for example, both a crystalline region and a non-crystalline region. The fine fibrous cellulose having both a crystalline region and a non-crystalline region and having an axial ratio within the above range is realized by, for example, a method for producing fine fibrous cellulose described later.

The cellulose component in fine fibrous cellulose can be classified into α-cellulose component and hemicellulose component. A lower ratio of hemicellulose is preferable because it is easy to obtain an effect of suppressing yellowing over time and yellowing by heating. The proportion of hemicellulose in the fine fibrous cellulose of the present invention is preferably less than 30%, more preferably less than 25%, still more preferably less than 20%.

Total amount of nitrogen contained in fine fibrous cellulose and free nitrogen contained in fine fibrous cellulose dispersion (hereinafter, "nitrogen amount", "nitrogen amount contained in fine fibrous cellulose" or "fine fibrous cellulose" The amount of nitrogen in the fiber) is preferably 0.09 mmol / g or less, more preferably 0.08 mmol / g or less, still more preferably 0.04 mmol / g or less. It is more preferably 0.02 mmol / g or less. The amount of nitrogen contained in the fine fibrous cellulose is preferably 0.001 mmol / g or more. The amount of nitrogen in the fine fibrous cellulose is a value measured by the following method. First, the dispersion liquid containing fine fibrous cellulose is adjusted to a solid content concentration of 1% by mass, and decomposed by the Kjeldahl method (JIS K 0102: 2016 44.1). After decomposition, the amount of ammonium ions (mmol) is measured by cation chromatography and divided by the amount of cellulose (g) used for the measurement to calculate the nitrogen content (mmol / g). The amount of nitrogen is the amount of nitrogen bonded to fine fibrous cellulose by ionic bond and / or covalent bond, and free nitrogen dissolved in the dispersion liquid which is not bound to fine fibrous cellulose by ionic bond and / or covalent bond. The total amount.

In the present embodiment, the amount of the substituent introduced in the fine fibrous cellulose is less than 0.5 mmol / g, and the substituent referred to here is preferably an anionic group. That is, the fine fibrous cellulose of the present invention is obtained by subjecting the fine fibrous cellulose having an anionic group to a substituent removing treatment, and the fine fibrous cellulose of the present invention is a fine fibrous cellulose having a substituent removed. It is fibrous cellulose.

Examples of the anionic group include a phosphate group or a substituent derived from a phosphorusoxo acid group (sometimes referred to simply as a phosphorusoxo acid group), a carboxy group or a substituent derived from a carboxy group (sometimes referred to simply as a carboxy group), and the like. Examples include a sulfone group or a substituent derived from a sulfone group (sometimes simply referred to as a sulfone group), a zantate group or a substituent derived from a zantate group (sometimes simply referred to as a zantate group). When a sulfone group or a substituent derived from a sulfone group is introduced via an ester bond, the substituent is referred to as a sulfur oxo acid group or a substituent derived from a sulfur oxo acid group (simply referred to as a sulfur oxo acid group). There is also). Among these, the anionic group is preferably at least one selected from a phosphate group or a substituent derived from a phosphorusoxo acid group, and a sulfone group or a substituent derived from a sulfone group, and is preferably a phosphorusoxo acid group or a substituent. More preferably, it is a substituent derived from a phosphoxoic acid group.

The phosphate group or the substituent derived from the phosphorus oxo acid group is, for example, a substituent represented by the following formula (1). A plurality of substituents represented by the following formula (1) may be introduced into each fine fibrous cellulose. In this case, the substituents represented by the following formula (1) to be introduced may be the same or different.

In the formula (1), a, b and n are natural numbers, and m is an arbitrary number (where a = b × m). At least one of the n α and α'is O ⁻ and the rest are R or OR. It is also possible that all of each α and α'are O ^−. The n αs may all be the same or different from each other. β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance.

R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, and an unsaturated-branched chain hydrocarbon, respectively. A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. Further, in the formula (1), n is preferably 1.

Examples of the saturated-linear hydrocarbon group include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like. Examples of the saturated-branched chain hydrocarbon group include an i-propyl group and a t-butyl group, but the group is not particularly limited. Examples of the saturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentyl group, a cyclohexyl group and the like. Examples of the unsaturated-linear hydrocarbon group include, but are not limited to, a vinyl group, an allyl group and the like. Examples of the unsaturated-branched chain hydrocarbon group include an i-propenyl group and a 3-butenyl group, but the group is not particularly limited. Examples of the unsaturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentenyl group, a cyclohexenyl group and the like. Examples of the aromatic group include, but are not limited to, a phenyl group, a naphthyl group and the like.

As the derivative groups in R, to the main chain or side chain of the various hydrocarbon group, a carboxy group, a carboxylate group (-COO ^-), hydroxy group, selected from the functional groups such as an amino group and an ammonium group Examples thereof include functional groups in which at least one of them is added or substituted, but the functional group is not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorus oxo acid group can be set to an appropriate range, the penetration into the fiber raw material is facilitated, and the yield of the fine cellulose fiber is increased. You can also do it. When a plurality of Rs are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the fine fibrous cellulose, the plurality of Rs are the same. It may be different.

β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include organic onium ions. Examples of the organic onium ion include an organic ammonium ion and an organic onium ion. Examples of the organic ammonium ion include aliphatic ammonium ion and aromatic ammonium ion, and examples of the organic onium ion include aliphatic phosphonium ion and aromatic phosphonium ion. Examples of monovalent or higher cations composed of inorganic substances include alkali metal ions such as sodium, potassium, and lithium, divalent metal ions such as calcium and magnesium, hydrogen ions, and ammonium ions. When a ^{plurality of β b +} are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the fine fibrous cellulose, the plurality of β ^{b +} are present. They may be the same or different. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing ^{β b + is heated and is easily industrially used, but is not particularly limited.} ..

Specific examples of the phosphoric acid group or the substituent derived from the phosphoric acid group include a phosphoric acid group (-PO ₃ H ₂ ), a salt of a phosphoric acid group, and a phosphite group (phosphonic acid group) (-PO). ₂ H _2), and salts of phosphorous acid (phosphonic acid group). Further, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a group in which a phosphoric acid group is condensed (for example, a pyrophosphate group), a group in which a phosphonic acid is condensed (for example, a polyphosphonic acid group), and a phosphoric acid ester group (for example, a phosphoric acid ester group). For example, it may be a monomethyl phosphate group, a polyoxyethylene alkyl phosphate group), an alkylphosphonic acid group (for example, a methylphosphonic acid group), or the like.

Further, the sulfone group (sulfo group or substituent derived from a sulfone group) is preferably a sulfur oxo acid group (sulfur oxo acid group or a substituent derived from a sulfur oxo acid group), for example, the following formula (2). It is preferably a substituent represented by. A plurality of substituents represented by the following formula (2) may be introduced into each fine fibrous cellulose. In this case, the substituents represented by the following formula (2) to be introduced may be the same or different.

In the above structural formula, b and n are natural numbers, p is 0 or 1, and m is an arbitrary number (where 1 = b × m). When n is 2 or more, a plurality of ps may be the same number or different numbers. In the above structural formula, β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include organic onium ions. Examples of the organic onium ion include an organic ammonium ion and an organic onium ion. Examples of the organic ammonium ion include aliphatic ammonium ion and aromatic ammonium ion, and examples of the organic onium ion include aliphatic phosphonium ion and aromatic phosphonium ion. Examples of monovalent or higher cations composed of inorganic substances include alkali metal ions such as sodium, potassium, and lithium, divalent metal ions such as calcium and magnesium, hydrogen ions, and ammonium ions. When a plurality of types of substituents represented by the above formula (2) are introduced into the fine fibrous cellulose, the plurality of β ^{b +} may be the same or different. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing ^{β b + is heated and is easily industrially used, but is not particularly limited.}

The amount of anionic groups introduced into the fine fibrous cellulose can be measured, for example, by a neutralization titration method. In the measurement by the neutralization titration method, the introduction amount is measured by determining the change in pH while adding an alkali such as an aqueous sodium hydroxide solution to the obtained slurry containing the fine fibrous cellulose.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped and the pH with respect to a slurry containing fine fibrous cellulose having a phosphoxoic acid group. The amount of the phosphorus oxo acid group introduced into the fine fibrous cellulose is measured, for example, as follows.
First, the slurry containing fine fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the same defibration treatment as the defibration treatment step described later may be performed on the measurement target before the treatment with the strong acid ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 1 is obtained. The titration curve shown in the upper part of FIG. 1 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 1 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, two points are confirmed in which the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point was equal to the amount of first dissociated acid of the fine fibrous cellulose contained in the slurry used for titration, and was required from the first end point to the second end point. The amount of alkali is equal to the amount of second dissociating acid of the fine fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the start to the second end point of titration is contained in the slurry used for titration. Equal to the total amount of dissociated acid in the fibrous cellulose. Then, the value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol / g). The amount of phosphorus oxo acid group introduced (or the amount of phosphorus oxo acid group) simply means the amount of the first dissociated acid.
In FIG. 1, the region from the start of titration to the first end point is referred to as a first region, and the region from the first end point to the second end point is referred to as a second region. For example, when the phosphoric acid group is a phosphoric acid group and the phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently. It decreases, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so that the amount of alkali required for the second region is reduced or the amount of alkali required for the second region is reduced. May be zero. In this case, there is only one point on the titration curve where the pH increment is maximum.

Since the denominator of the above-mentioned phosphorus oxo acid group introduction amount (mmol / g) indicates the mass of the acid-type fine fibrous cellulose, the amount of the phosphorus oxo acid group contained in the acid-type fine fibrous cellulose (hereinafter, phosphorus oxo acid). It is called the base amount (acid type)). On the other hand, when the counterion of the phosphorus oxo acid group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of the fine fibrous cellulose when the cation C is a counterion. By doing so, the amount of phosphorus oxo acid groups (hereinafter, the amount of phosphorus oxo acid groups (C type)) possessed by the fine fibrous cellulose in which the cation C is a counter ion can be obtained.
That is, it is calculated by the following formula.
Amount of phosphorus oxo acid group (C type) = Amount of phosphorus oxo acid group (acid type) / {1+ (W-1) × A / 1000}
A [mmol / g]: Total anion amount derived from the phosphoric acid group of the fine fibrous cellulose (total dissociated acid amount of the phosphoric acid group)
W: Formulated amount per valence of cation C (for example, Na is 23, Al is 9)

FIG. 2 is a graph showing the relationship between the amount of NaOH dropped and the pH of a dispersion liquid containing fine fibrous cellulose having a carboxy group as an anionic group. The amount of the carboxy group introduced into the fine fibrous cellulose is measured, for example, as follows.
First, the dispersion liquid containing fine fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the same defibration treatment as the defibration treatment step described later may be performed on the measurement target before the treatment with the strong acid ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 2 is obtained. The titration curve shown in the upper part of FIG. 2 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 2 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, in the curve plotting the pH measured with respect to the amount of alkali added, one point was confirmed where the increment (differential value of pH with respect to the amount of alkali dropped) became maximum, and this maximum point was the first. Called one end point. Here, the region from the start of titration to the first end point in FIG. 2 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the dispersion used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the dispersion containing the fine fibrous cellulose to be titrated, so that the amount of carboxy group introduced (mmol) mmol / g) is calculated.

Since the denominator of the above-mentioned carboxy group introduction amount (mmol / g) is the mass of the acid-type fine fibrous cellulose, the carboxy group amount of the acid-type fine fibrous cellulose (hereinafter referred to as the carboxy group amount (hereinafter referred to as carboxy group amount). It is called (acid type)). On the other hand, when the counterion of the carboxy group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted into the mass of the fine fibrous cellulose when the cation C is a counterion. This makes it possible to determine the amount of carboxy group (hereinafter, carboxy group amount (C type)) possessed by the fine fibrous cellulose in which the cation C is a counterion. That is, it is calculated by the following formula.
Carboxy group amount (C type) = Carboxy group amount (acid type) / {1+ (W-1) x (carboxy group amount (acid type)) / 1000}
W: Formulated amount per valence of cation C (for example, Na is 23, Al is 9)

In the measurement of the amount of anionic groups by the titration method, accurate values can be obtained, such as when the amount of one drop of sodium hydroxide aqueous solution is too large, or when the titration interval is too short, the amount of anionic groups is lower than originally intended. Sometimes not. As an appropriate dropping amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of a 0.1 N sodium hydroxide aqueous solution every 5 to 30 seconds. Further, in order to eliminate the influence of carbon dioxide dissolved in the fine fibrous cellulose-containing slurry, for example, it is desirable to measure while blowing an inert gas such as nitrogen gas into the slurry from 15 minutes before the start of titration to the end of titration. ..

Further, the amount of the sulfone group introduced into the fine fibrous cellulose can be calculated by freeze-drying the slurry containing the fine fibrous cellulose and measuring the amount of sulfur in the crushed sample. Specifically, a slurry containing fine fibrous cellulose is freeze-dried, and the crushed sample is pressure-heated and decomposed with nitric acid in a closed container, diluted appropriately, and the amount of sulfur is measured by ICP-OES. do. The value calculated by dividing by the absolute dry mass of the fine fibrous cellulose tested is taken as the sulfone group amount (unit: mmol / g) of the fine fibrous cellulose.

The amount of the zantate group introduced into the fine fibrous cellulose can be measured by the following method by the Bredee method. First, add 40 mL of saturated ammonium chloride solution to 1.5 parts by mass (absolute dry mass) of fine fibrous cellulose, mix well while crushing the sample with a glass rod, leave it for about 15 minutes, and then GFP filter paper (GS manufactured by ADVANTEC). Filter with -25) and wash thoroughly with saturated ammonium chloride solution. Then, the sample is placed in a 500 mL tall beaker together with the GFP filter paper, 50 mL of 0.5 M sodium hydroxide solution (5 ° C.) is added, the mixture is stirred, and the mixture is left for 15 minutes. After adding the phenolphthalein solution until the solution turns pink, 1.5 M acetic acid is added, and the point at which the solution turns from pink to colorless is defined as the neutralization point. After neutralization, add 250 mL of distilled water, stir well, and add 10 mL of 1.5 M acetic acid and 10 mL of 0.05 mol / L iodine solution using a whole pipette. Then, this solution is titrated with a 0.05 mol / L sodium thiosulfate solution, and the amount of zantate group is calculated from the following formula from the titration amount of sodium thiosulfate and the absolute dry mass of the fine fibrous cellulose.
Zantate group amount (mmol / g) = (0.05 × 10 × 2-0.05 × sodium thiosulfate titration (mL)) / 1000 / Absolute dry mass (g) of fine fibrous cellulose

In the present embodiment, the fine fibrous cellulose preferably has a carbamide group. In the present specification, the carbamide group is preferably a group represented by the following structural formula.

In the above structural formula, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, and an unsaturated-branched group. A chain hydrocarbon group, an aromatic group, or an inducing group thereof. Above all, it is particularly preferable that R is a hydrogen atom.

The amount of carbamide group introduced in the fine fibrous cellulose is preferably 0.001 mmol / g or more. The amount of the carbamide group introduced in the fine fibrous cellulose is preferably 0.08 mmol / g or less, more preferably 0.04 mmol / g or less, and further preferably 0.02 mmol / g or less. preferable. Here, the amount of the carbamide group introduced in the fine fibrous cellulose can be calculated by freeze-drying the slurry containing the fine fibrous cellulose and further pulverizing the sample by micronitrogen analysis. The amount of carbamide group introduced per unit mass of fine fibrous cellulose (mmol / g) is obtained by dividing the nitrogen content (g / g) per unit mass of fine fibrous cellulose obtained by trace nitrogen analysis by the atomic weight of nitrogen. Can be calculated by

Further, in the present embodiment, when the fine fibrous cellulose is used as an aqueous dispersion having a concentration of 0.2% by mass, the haze of the aqueous dispersion is preferably 45% or less, more preferably 35% or less. It is preferably 25% or less, and more preferably 25% or less. The haze of the aqueous dispersion may be 0%. Here, the haze of the aqueous dispersion is a value measured according to JIS K 7136: 2000 using a haze meter and a glass cell for liquid having an optical path length of 1 cm. The zero point measurement is performed with ion-exchanged water contained in the same glass cell. Further, the dispersion liquid to be measured is allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours before the measurement, and the liquid temperature of the dispersion liquid is set to 23 ° C.

In the present embodiment, when the fine fibrous cellulose is used as a dispersion liquid (water dispersion liquid) having a concentration of 1% by mass, the pH of the dispersion liquid is preferably 3 or more, more preferably 4 or more. It is more preferably 5 or more. The pH of the dispersion is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less. By setting the pH of the dispersion in the above range, yellowing of the resin composition or the resin molded product can be suppressed more effectively. In order to keep the pH of the dispersion in the above range, the same method as in the <pH adjustment step> described later can be taken.

It is preferable that the amount of free nitrogen in the dispersion containing fine fibrous cellulose is small. The amount of free nitrogen in the dispersion can be measured by measuring the nitrogen concentration in the filtrate when the fine fibrous cellulose dispersion is filtered. For example, the free nitrogen concentration in the dispersion having a fine fibrous cellulose concentration of 0.2% by mass is preferably 100 ppm or less, more preferably 80 ppm or less, further preferably 70 ppm or less, and even more preferably 60 ppm. It is more preferably less than or equal to, more preferably 50 ppm or less, further preferably 40 ppm or less, and particularly preferably 30 ppm or less. The nitrogen concentration in the dispersion having a fine fibrous cellulose concentration of 0.2% by mass may be 0 ppm. Since free nitrogen present in the dispersion liquid causes coloring, setting the nitrogen concentration in the filtrate within the above range is more effective for yellowing of the resin composition containing fine fibrous cellulose and the resin molded body. Can be suppressed. Here, the method for measuring the nitrogen concentration in the filtrate is as follows. First, distilled water is added so that the concentration of fine fibrous cellulose is 0.2% by mass, and after stirring for 24 hours, filtration is performed using a filter medium having a pore size of 0.45 μm to obtain a filtrate. Then, the nitrogen concentration (ppm) in the filtrate is measured by trace nitrogen analysis.

The content of the fine fibrous cellulose in the rubber composition is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the rubber composition. It is more preferably 0% by mass or more. The content of the fine fibrous cellulose is preferably 50% by mass or less, more preferably 35% by mass or less, and more preferably 20% by mass or less, based on the total mass of the rubber composition. More preferred. By setting the content of the fine fibrous cellulose within the above range, it becomes easy to obtain a molded product having excellent designability and suppressed coloring. Further, by setting the content of the fine fibrous cellulose within the above range, the tensile properties of the molded product obtained by molding the rubber composition can be enhanced.

(Optional ingredient)
The rubber composition of the present invention may contain an optional component in addition to the above-mentioned resin and fibrous cellulose. Optional components include, for example, fillers, pigments, dyes, ultraviolet absorbers, dispersants, cross-linking agents (sulfur, sulfur compounds, etc.), cross-linking accelerators (vulcanization accelerators, etc.), and cross-linking accelerators (vulcanization accelerator aids). Agents, etc.), silane coupling agents, hardeners, oils, hardened resins, waxes, anti-aging agents, etc.
The above-mentioned rubber component is a pre-crosslinking raw material (a raw material in which a cross-linked structure is not substantially formed by vulcanization or the like) such as raw rubber, latex or rubber solution used for forming solid rubber such as synthetic rubber and natural rubber. In some cases, the sulfur in the optional ingredients, or other cross-linking agents, is an essential ingredient. Further, when the above-mentioned rubber component is a pre-crosslinking raw material such as raw rubber, latex or rubber solution used for forming solid rubber such as synthetic rubber and natural rubber, the above-mentioned optional in a molded body obtained by molding a rubber composition. Sulfur in the components, or other cross-linking agents, exists as a cross-linked structure derived from these compounds.

Further, the rubber composition may contain a water-soluble organic compound as an optional component. Examples of the water-soluble organic compound include sugars, water-soluble polymers, urea and the like. Specific examples thereof include trehalose, urea, polyethylene glycol (PEG), polyethylene oxide (PEO), carboxymethyl cellulose, polyvinyl alcohol (PVA) and the like. In addition, as water-soluble organic compounds, alkyl methacrylate / acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide. , Xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seed, alginic acid, purulan, carrageenan, pectin, cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, starches such as amylose, glycerin , Diglycerin, polyglycerin, hyaluronic acid, metal salts of hyaluronic acid can also be used.

Further, the rubber composition may contain a known pigment as an optional component. Examples of the pigment include kaolin (containing clay), calcium carbonate, titanium oxide, zinc oxide, amorphous silica (containing colloidal silica), aluminum oxide, zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, and oxidation. Examples thereof include magnesium, diatomaceous earth, styrene-based plastic pigments, hydrotalcites, urea resin-based plastic pigments, benzoguanamine-based plastic pigments, and the like.

The content of the optional component is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, based on the total mass of the rubber composition. ..

(Manufacturing method of fine fibrous cellulose)
The above-mentioned fine fibrous cellulose is preferably obtained through the step (A) of removing at least a part of the substituent from the fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less. .. Here, the substituent contained in the fine fibrous cellulose used in the step (A) is preferably an anionic group, and more preferably a phosphoxoic acid group or a substituent derived from the phosphoxoic acid group. Further, the fine fibrous cellulose used in the step (A) preferably has a carbamide group.

(Step (A))
The step (A) is a step of removing at least a part of the substituent from the fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less. Hereinafter, a method for producing fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less (fine fibrous cellulose used in step (A)) will be described.

<Fiber raw material>
The fine fibrous cellulose used in the step (A) is produced from a fiber raw material containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, but is, for example, broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), and unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton pulp such as cotton linter and cotton lint, and non-wood pulp such as hemp, straw and bagasse. The deinking pulp is not particularly limited, and examples thereof include deinking pulp made from recycled paper. As the pulp of this embodiment, one of the above may be used alone, or two or more of them may be mixed and used. Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of availability. Further, among wood pulps, it is possible to obtain long-fiber fine fibrous cellulose having a large cellulose ratio and a high yield of fine fibrous cellulose during defibration treatment, and having a small decomposition of cellulose in the pulp and a large axial ratio. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable. It should be noted that the viscosity tends to be high when the fine fibrous cellulose of long fibers having a large axial ratio is used.

As the fiber raw material containing cellulose, for example, cellulose contained in ascidians and bacterial cellulose produced by acetic acid bacteria can also be used. Further, instead of the fiber raw material containing cellulose, a fiber formed by a linear nitrogen-containing polysaccharide polymer such as chitin or chitosan can also be used.

<Linoxo acid group introduction process>
The fine fibrous cellulose used in the step (A) has a substituent. Therefore, the process for producing the fine fibrous cellulose used in the step (A) preferably includes a substituent introduction step, and more preferably an anionic group introduction step. Examples of the anionic group introduction step include a phosphorus oxo acid group introduction step. In the phosphorus oxo acid group introduction step, at least one compound (hereinafter, also referred to as “compound A”) selected from compounds capable of introducing a phosphorus oxo acid group by reacting with a hydroxyl group of a fiber raw material containing cellulose is used as cellulose. It is a step of acting on a fiber raw material containing. By this step, a phosphorus oxo acid group-introduced fiber can be obtained.

In the phosphorus oxo acid group introduction step according to the present embodiment, the reaction between the fiber raw material containing cellulose and compound A is carried out in the presence of at least one selected from urea and its derivatives (hereinafter, also referred to as “compound B”). Is preferable.

As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B, there is a method of mixing the compound A and the compound B with respect to the dry state, the wet state or the slurry-like fiber raw material. Of these, since the reaction uniformity is high, it is preferable to use a fiber raw material in a dry state or a wet state, and it is particularly preferable to use a fiber raw material in a dry state. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. Examples of the compound A and the compound B include a method of adding the compound A and the compound B to the fiber raw material in the form of powder, in the form of a solution dissolved in a solvent, or in the state of being heated to a melting point or higher and melted. Of these, since the reaction uniformity is high, it is preferable to add the solution in the form of a solution dissolved in a solvent, particularly in the state of an aqueous solution. Further, the compound A and the compound B may be added to the fiber raw material at the same time, may be added separately, or may be added as a mixture. The method for adding the compound A and the compound B is not particularly limited, but when the compound A and the compound B are in the form of a solution, the fiber raw material may be immersed in the solution to absorb the liquid and then taken out, or the fiber raw material may be taken out. The solution may be dropped into the water. Further, a required amount of compound A and compound B may be added to the fiber raw material, or an excess amount of compound A and compound B may be added to the fiber raw material, respectively, and then the surplus compound A and compound B may be added by pressing or filtering. It may be removed.

The compound A used in this embodiment may be any compound having a phosphorus atom and capable of forming an ester bond with cellulose, and may be phosphoric acid or a salt thereof, phosphoric acid or a salt thereof, dehydration condensed phosphoric acid or a salt thereof. Examples thereof include salts and anhydrous phosphoric acid (diphosphoric pentoxide), but the present invention is not particularly limited. As the phosphoric acid, those having various puritys can be used, and for example, 100% phosphoric acid (normal phosphoric acid) or 85% phosphoric acid can be used. Examples of phosphorous acid include 99% phosphorous acid (phosphonic acid). The dehydration-condensed phosphoric acid is one in which two or more molecules of phosphoric acid are condensed by a dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Examples of the phosphate, sulphate, and dehydration-condensed phosphate include phosphoric acid, sulphite, or lithium salt of dehydration-condensed phosphoric acid, sodium salt, potassium salt, ammonium salt, and the like. It can be a sum. Of these, from the viewpoints of high efficiency of introducing phosphoric acid group, easy improvement of defibration efficiency in the defibration process described later, low cost, and easy industrial application, phosphoric acid and sodium phosphate Salt, potassium salt of phosphoric acid, ammonium salt or phosphoric acid of phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, ammonium salt of phosphoric acid are preferable, and phosphoric acid, sodium dihydrogen phosphate, Disodium hydrogen phosphate, ammonium dihydrogen phosphate, or phosphoric acid and sodium phosphite are more preferred.

The amount of compound A added to the fiber raw material is not particularly limited, but for example, when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material (absolute dry mass) is 0.5% by mass or more. It is preferably 100% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and further preferably 2% by mass or more and 30% by mass or less. By setting the amount of phosphorus atom added to the fiber raw material within the above range, the yield of fine fibrous cellulose can be further improved. On the other hand, by setting the addition amount of the phosphorus atom to the fiber raw material to be equal to or less than the above upper limit value, the effect of improving the yield and the cost can be balanced.

The compound B used in this embodiment is at least one selected from urea and its derivatives as described above. Examples of compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.
From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. Further, from the viewpoint of further improving the uniformity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.

The amount of compound B added to the fiber raw material (absolute dry mass) is not particularly limited, but is preferably 1% by mass or more and 500% by mass or less, and more preferably 10% by mass or more and 400% by mass or less. It is more preferably 100% by mass or more and 350% by mass or less.

In the reaction between the fiber raw material containing cellulose and compound A, for example, amides or amines may be contained in the reaction system in addition to compound B. Examples of the amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine in particular is known to act as a good reaction catalyst.

In the phosphorus oxo acid group introduction step, it is preferable to add or mix the compound A and the compound B to the fiber raw material and then heat-treat the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature at which a phosphorus oxo acid group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is, for example, preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. In addition, equipment having various heat media can be used for the heat treatment, for example, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, a fluidized layer drying device, and a band. A mold drying device, a filtration drying device, a vibration flow drying device, an air flow drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, a high frequency drying device, and a hot air drying device can be used.

In the heat treatment according to the present embodiment, for example, a method of adding compound A to a thin sheet-shaped fiber raw material by a method such as impregnation and then heating, or a method of heating while kneading or stirring the fiber raw material and compound A with a kneader or the like. Can be adopted. This makes it possible to suppress unevenness in the concentration of compound A in the fiber raw material and to more uniformly introduce the phosphoric acid group onto the surface of the cellulose fiber contained in the fiber raw material. This is because when the water molecules move to the surface of the fiber raw material due to drying, the dissolved compound A is attracted to the water molecules by the surface tension and also moves to the surface of the fiber raw material (that is, the concentration unevenness of the compound A is caused. It is considered that this is due to the fact that it can be suppressed.

Further, the heating device used for the heat treatment always keeps the water content retained by the slurry and the water content generated by the dehydration condensation (phosphate esterification) reaction between the compound A and the hydroxyl group contained in the cellulose or the like in the fiber raw material. It is preferable that the device can be discharged to the outside of the device system. Examples of such a heating device include a ventilation type oven and the like. By constantly discharging the water in the apparatus system, it is possible to suppress the acid hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, and also to suppress the acid hydrolysis of the sugar chain in the fiber. can. Therefore, it is possible to obtain fine fibrous cellulose having a high axial ratio.

The heat treatment time is preferably 1 second or more and 300 minutes or less, more preferably 1 second or more and 1000 seconds or less, and 10 seconds or more and 800 seconds or less after the water is substantially removed from the fiber raw material. Is more preferable. In the present embodiment, the amount of the phosphorus oxo acid group introduced can be within a preferable range by setting the heating temperature and the heating time within appropriate ranges.

The phosphorus oxo acid group introduction step may be performed at least once, but may be repeated twice or more. By performing the phosphorus oxo acid group introduction step two or more times, many phosphorus oxo acid groups can be introduced into the fiber raw material.

The amount of the phosphorus oxo acid group introduced in the phosphorus oxo acid group introduction step is preferably 0.60 mmol / g or more, more preferably 0.70 mmol / g or more, and more preferably 0.80 mmol / g per 1 g (mass) of the fiber raw material. It is more preferably g or more, further preferably 1.00 mmol / g or more, and particularly preferably 1.20 mmol / g or more. The amount of the phosphorus oxo acid group introduced is, for example, preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and 3.00 mmol / g or less per 1 g (mass) of the fiber raw material. It is more preferable to have. The fact that the amount of the phosphorus oxo acid group introduced in the phosphorus oxo acid group introduction step is within the above range means that the amount of the substituent of the fine fibrous cellulose provided in the step (A) is within the above range. do. By setting the introduction amount of the phosphorus oxo acid group within the above range, the introduction amount of the substituent of the fine fibrous cellulose provided in the step (A) can be within the above range, and as a result, the final fiber width can be obtained. It becomes easy to produce fine fibrous cellulose having a diameter of 100 nm or less. In addition, the design and tensile properties of the molded product containing the fine fibrous cellulose of the present invention can be more effectively enhanced.

<Carboxy group introduction process>
The step of producing the fine fibrous cellulose used in the step (A) may include a carboxy group introduction step as an anionic group introduction step. The carboxy group introduction step has an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a group derived from carboxylic acid or a derivative thereof, or a group derived from carboxylic acid with respect to the fiber raw material containing cellulose. It is carried out by treatment with an acid anhydride of a compound or a derivative thereof.

The compound having a group derived from a carboxylic acid is not particularly limited, and for example, a dicarboxylic acid compound such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, and itaconic acid, citric acid, aconitic acid and the like. Examples include tricarboxylic acid compounds. The derivative of the compound having a group derived from a carboxylic acid is not particularly limited, and examples thereof include an acid anhydride derivative of the compound having a carboxy group and an acid anhydride derivative of the compound having a carboxy group. The imide of the acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinic acidimide, and phthalateimide.

The acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a dicarboxylic acid compound such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Acid anhydride is mentioned. The derivative of the acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a compound having a carboxy group such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride and the like. Examples thereof include those in which at least a part of the hydrogen atom of the acid anhydride is substituted with a substituent such as an alkyl group or a phenyl group.

When the TEMPO oxidation treatment is performed in the carboxy group introduction step, it is preferable to perform the treatment under conditions of pH 6 or more and 8 or less, for example. Such a treatment is also referred to as a neutral TEMPO oxidation treatment. The neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst, and the like. This can be done by adding a nitroxy radical and sodium hypochlorite as a sacrificial reagent. Further, by coexisting with sodium chlorite, the aldehyde generated in the oxidation process can be efficiently oxidized to the carboxy group. Further, the TEMPO oxidation treatment may be carried out under the condition that the pH is 10 or more and 11 or less. Such a treatment is also referred to as an alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be performed, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a co-catalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. ..

The amount of the carboxy group introduced in the carboxy group introduction step is preferably 0.60 mmol / g or more, more preferably 0.65 mmol / g or more per 1 g (mass) of the fiber raw material. The amount of the carboxy group introduced is, for example, preferably 3.65 mmol / g or less, more preferably 3.00 mmol / g or less, and 2.50 mmol / g or less per 1 g (mass) of the fiber raw material. It is more preferable, and it is particularly preferable that it is 2.00 mmol / g or less. The fact that the amount of the carboxy group introduced in the carboxy group introduction step is within the above range means that the amount of the substituent of the fine fibrous cellulose provided in the step (A) is within the above range. By setting the introduction amount of the carboxy group within the above range, the introduction amount of the substituent of the fine fibrous cellulose provided in the step (A) can be within the above range, and as a result, the fiber width is 100 nm or less. It becomes easy to produce fine fibrous cellulose. In addition, the design and tensile properties of the molded product containing the fine fibrous cellulose of the present invention can be more effectively enhanced.

<Sulfone group (sulfur oxoacid group) introduction process>
The step of producing the fine fibrous cellulose provided in the step (A) may include a sulfone group introduction step as an anionic group introduction step. In the sulfone group introduction step, cellulose fibers having a sulfone group (sulfone group-introduced fiber) can be obtained by reacting the hydroxyl group of the fiber raw material containing cellulose with sulfonic acid.

In the sulfone group introduction step, at least one selected from compounds capable of introducing a sulfone group by reacting with the hydroxyl group of the fiber raw material containing cellulose instead of the compound A in the above-mentioned <phosphoroxo acid group introduction step>. A compound (hereinafter, also referred to as “Compound C”) is used. The compound C may be any compound having a sulfur atom and capable of forming an ester bond with cellulose, and examples thereof include sulfuric acid or a salt thereof, sulfurous acid or a salt thereof, and sulfate amide, but the compound C is not particularly limited. As the sulfuric acid, those having various puritys can be used, and for example, 96% sulfuric acid (concentrated sulfuric acid) can be used. Examples of sulfurous acid include 5% sulfurous acid water. Examples of the sulfate or sulfite include lithium salts, sodium salts, potassium salts and ammonium salts of sulfates or sulfites, and these can have various neutralization degrees. As the sulfuric acid amide, sulfamic acid or the like can be used. In the sulfone group introduction step, it is preferable to use the compound B in the above-mentioned <phosphoroacid group introduction step> in the same manner.

In the sulfone group introduction step, it is preferable to mix the cellulose raw material with an aqueous solution containing sulfonic acid and urea and / or a urea derivative, and then heat-treat the cellulose raw material. As the heat treatment temperature, it is preferable to select a temperature at which the sulfone group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and even more preferably 150 ° C. or higher. The heat treatment temperature is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 200 ° C. or lower.

In the heat treatment step, it is preferable to heat until the water content is substantially eliminated. Therefore, the heat treatment time varies depending on the amount of water contained in the cellulose raw material and the amount of the aqueous solution containing sulfonic acid and urea and / or a urea derivative, but is, for example, 10 seconds or more and 10,000 seconds or less. Is preferable. Equipment having various heat media can be used for the heat treatment, for example, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, a fluidized layer drying device, and a band type drying. An apparatus, a filtration drying device, a vibration flow drying device, an air flow drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, a high frequency drying device, and a hot air drying device can be used.

The amount of the sulfone group introduced in the sulfone group introduction step is preferably 0.60 mmol / g or more, more preferably 0.70 mmol / g or more, and 0.80 mmol / g or more per 1 g (mass) of the fiber raw material. It is more preferably 1.00 mmol / g or more, and particularly preferably 1.20 mmol / g or more. The amount of the sulfone group introduced is, for example, preferably 5.00 mmol / g or less, and more preferably 3.00 mmol / g or less per 1 g (mass) of the fiber raw material. The fact that the amount of the sulfone group introduced in the sulfone group introduction step is within the above range means that the amount of the substituent of the fine fibrous cellulose provided in the step (A) is within the above range. By setting the introduction amount of the sulfone group within the above range, the introduction amount of the substituent of the fine fibrous cellulose provided in the step (A) can be within the above range, and as a result, the fiber width is 100 nm or less. It becomes easy to produce fine fibrous cellulose. In addition, the design and tensile properties of the molded product containing the fine fibrous cellulose of the present invention can be more effectively enhanced.

<Zantate group introduction process>
The step of producing the fine fibrous cellulose used in the step (A) may include a zantate group introduction step as an anionic group introduction step. In the zantate group introduction step, a cellulose fiber having a zantate group (zantate group-introduced fiber) can be obtained by substituting the hydroxyl group of the fiber raw material containing cellulose with a zantate group represented by the following formula (2).
―OCSS ⁻ M ^＋ …… (2)
Here, M ⁺ is at least one selected from hydrogen ion, monovalent metal ion, ammonium ion, aliphatic or aromatic ammonium ion.

In the zantate group introduction step, first, the fiber raw material containing cellulose is treated with an alkaline solution to obtain alkaline cellulose. Examples of the alkaline solution include an aqueous solution of alkali metal hydroxide and an aqueous solution of alkaline earth metal hydroxide. Above all, the alkaline solution is preferably an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, and particularly preferably an aqueous solution of sodium hydroxide. When the alkaline solution is an alkaline alkali metal hydroxide aqueous solution, the alkali metal hydroxide concentration in the alkaline metal hydroxide aqueous solution is preferably 4% by mass or more, and more preferably 5% by mass or more. Further, the alkali metal hydroxide concentration in the aqueous alkali metal hydroxide solution is preferably 9% by mass or less. By setting the alkali metal hydroxide concentration to the above lower limit or higher, the mercerization of cellulose can be sufficiently promoted, and the amount of by-products generated during the subsequent zantate formation can be reduced, and as a result, it is possible to reduce the amount of by-products. The yield of the zantate group-introduced fiber can be increased. As a result, the defibration treatment described later can be performed more effectively. Further, by setting the alkali metal hydroxide concentration to the above upper limit value or less, it is possible to suppress the permeation of the alkali metal hydroxide aqueous solution into the crystal region of cellulose while promoting mercerization, so that the cellulose I The crystal structure of the mold can be easily maintained, and the yield of fine fibrous cellulose can be further increased.

The time of the alkali treatment is preferably 30 minutes or more, and more preferably 1 hour or more. The alkali treatment time is preferably 6 hours or less, and more preferably 5 hours or less. By setting the alkali treatment time within the above range, the final yield can be increased and the productivity can be increased.

It is preferable that the alkaline cellulose obtained by the above alkaline treatment is then solid-liquid separated to remove the aqueous solution as much as possible. As a result, the water content in the subsequent zantate treatment can be reduced and the reaction can be promoted. As a solid-liquid separation method, a general dehydration method such as centrifugation or filtration can be used. The concentration of the alkali metal hydroxide contained in the alkali cellulose after solid-liquid separation is preferably 3% by mass or more and 8% by mass or less with respect to the total mass of the alkali cellulose after solid-liquid separation.

In the zantate group introduction step, the zantate treatment step is performed after the alkali treatment. The xanthate treatment process by reacting carbon disulfide (CS ₂₎ in the alkali cellulose, (- ^O - Na ⁺⁾ group (-OCSS ^- Na ⁺⁾ to obtain a xanthate group introduction fibers based on. In the above, the metal ion introduced into the alkali cellulose is represented by Na ⁺ , but the same reaction proceeds with other alkali metal ions.

In the zantate treatment, it is preferable to supply 10% by mass or more of carbon disulfide with respect to the absolute dry mass of the cellulose in the alkaline cellulose. Further, in the zantate treatment, the contact time between carbon disulfide and alkaline cellulose is preferably 30 minutes or more, and more preferably 1 hour or more. When carbon disulfide comes into contact with the alkaline cellulose, zantate formation proceeds rapidly, but it takes time for the carbon disulfide to penetrate into the inside of the alkaline cellulose, so the reaction time is preferably set within the above range. On the other hand, the contact time between carbon disulfide and alkaline cellulose may be as long as 6 hours or less, which allows sufficient penetration into the dehydrated alkaline cellulose lumps and almost all the reactionable zantate. Can be completed.

The reaction temperature in the zantate treatment is preferably 46 ° C. or lower. By setting the reaction temperature within the above range, it becomes easy to suppress the decomposition of alkaline cellulose. Further, by setting the reaction temperature within the above range, it becomes easy to react uniformly, so that it is possible to suppress the formation of by-products and further suppress the removal of the formed zantate groups.

The amount of the zantate group introduced in the zantate group introduction step is preferably 0.60 mmol / g or more, more preferably 0.70 mmol / g or more, and 0.80 mmol / g or more per 1 g (mass) of the fiber raw material. It is more preferably 1.00 mmol / g or more, and particularly preferably 1.20 mmol / g or more. The amount of the zantate group introduced is, for example, preferably 5.00 mmol / g or less, and more preferably 3.00 mmol / g or less per 1 g (mass) of the fiber raw material. The fact that the amount of the zantate group introduced in the zantate group introduction step is within the above range means that the amount of the substituent of the fine fibrous cellulose provided in the step (A) is within the above range. By setting the introduction amount of the zantate group within the above range, the introduction amount of the substituent of the fine fibrous cellulose used in the step (A) can be within the above range, and as a result, the fiber width is 10 nm or less. It becomes easy to produce fine fibrous cellulose. In addition, the design and tensile properties of the molded product containing the fine fibrous cellulose of the present invention can be more effectively enhanced.

<Washing process>
In the step of producing the fine fibrous cellulose used in the step (A), a washing step can be performed on the anionic group-introduced fiber, if necessary. The washing step is performed by washing the anionic group-introduced fibers with, for example, water or an organic solvent. Further, the cleaning step may be performed after each step described later, and the number of cleaning steps performed in each cleaning step is not particularly limited.

<Alkaline treatment process>
In the step of producing the fine fibrous cellulose used in the step (A), the fiber raw material may be treated with an alkali between the step of introducing an anionic group and the step of the defibration treatment described later. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the anionic group-introduced fiber in an alkaline solution.

The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkaline compound or an organic alkaline compound. In this embodiment, it is preferable to use, for example, sodium hydroxide or potassium hydroxide as the alkaline compound because of its high versatility. Further, the solvent contained in the alkaline solution may be either water or an organic solvent. Among them, the solvent contained in the alkaline solution is preferably a polar solvent containing water or a polar organic solvent exemplified by alcohol, and more preferably an aqueous solvent containing at least water. As the alkaline solution, for example, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is preferable because of its high versatility.

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time of the anionic group-introduced fiber in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the anionic group-introduced fiber. Is more preferable.

In order to reduce the amount of the alkaline solution used in the alkaline treatment step, the anionic group-introduced fiber may be washed with water or an organic solvent after the anionic group introduction step and before the alkaline treatment step. After the alkali treatment step and before the defibration treatment step, it is preferable to wash the alkali-treated anionic group-introduced fiber with water or an organic solvent from the viewpoint of improving handleability.

<Acid treatment process>
In the step of producing the fine fibrous cellulose used in the step (A), the fiber raw material may be acid-treated between the step of introducing an anionic group and the defibration treatment step described later. For example, the anionic group introduction step, the acid treatment, the alkali treatment and the defibration treatment may be performed in this order.

The method of the acid treatment is not particularly limited, and examples thereof include a method of immersing the fiber raw material in an acidic liquid containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably, for example, 10% by mass or less, and more preferably 5% by mass or less. The pH of the acidic solution used is not particularly limited, but is preferably 0 or more and 4 or less, and more preferably 1 or more and 3 or less. As the acid contained in the acidic liquid, for example, an inorganic acid, a sulfonic acid, a carboxylic acid or the like can be used. Examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, phosphoric acid, boric acid and the like. Examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. Examples of the carboxylic acid include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, tartaric acid and the like. Among these, it is particularly preferable to use hydrochloric acid or sulfuric acid.

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the fiber raw material. Is more preferable.

<Nitrogen removal treatment>
The step of producing the fine fibrous cellulose provided in the step (A) may further include a step of reducing the amount of nitrogen introduced into the fibrous cellulose and the amount of nitrogen present in the system (nitrogen removal treatment step). By reducing the amount of nitrogen, it is possible to obtain fine fibrous cellulose that can further suppress coloring. The nitrogen removal treatment step may be provided after the uniform dispersion treatment step in the step (B) described later, but is preferably provided before the uniform dispersion treatment step in the step (B) described later. Further, it is preferably provided before the defibration treatment step in the step (A) described later.

In the nitrogen removal treatment step, it is preferable to adjust the pH of the slurry containing the anionic group-introduced fiber to 10 or more and perform the heat treatment. In the heat treatment, the liquid temperature of the slurry is preferably 50 ° C. or higher and 100 ° C. or lower, and the heating time is preferably 15 minutes or longer and 180 minutes or lower. When adjusting the pH of the slurry containing the anionic group-introduced fiber, it is preferable to add an alkaline compound that can be used in the above-mentioned alkali treatment step to the slurry.

After the nitrogen removal treatment step, a washing step can be performed on the anionic group-introduced fiber, if necessary. The washing step is performed by washing the anionic group-introduced fibers with, for example, water or an organic solvent. Further, the number of cleanings performed in each cleaning step is not particularly limited.

<Defibration treatment>
The step of producing the fine fibrous cellulose used in the step (A) includes a defibration treatment step. As a result, fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less can be obtained. In the defibration treatment step, for example, a defibration treatment apparatus can be used. The defibration processing device is not particularly limited, but for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, a twin-screw kneader, etc. A vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, a beater, or the like can be used. Among the above-mentioned defibration processing devices, it is more preferable to use a high-speed defibrator and a high-pressure homogenizer, which are less affected by crushed media and have less risk of contamination.

The treatment conditions in the defibration treatment step are not particularly limited, but when a high-pressure homogenizer is used, for example, the pressure during the treatment is preferably 1 MPa or more and 350 MPa or less, more preferably 10 MPa or more and 300 MPa or less, and further preferably 50 MPa or more and 250 MPa or less.

In the defibration treatment step, for example, it is preferable to dilute the anionic group-introduced fiber with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from water and an organic solvent such as a polar organic solvent can be used. The polar organic solvent is not particularly limited, but for example, alcohols, polyhydric alcohols, ketones, ethers, esters, aprotic polar solvents and the like are preferable. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol and glycerin. Examples of the ketone include acetone, methyl ethyl ketone (MEK) and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monon-butyl ether, propylene glycol monomethyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate and the like. Examples of the aprotonic polar solvent include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.

The solid content concentration of the fine fibrous cellulose during the defibration treatment can be appropriately set. Further, the slurry obtained by dispersing the anionic group-introduced fiber in a dispersion medium may contain a solid content other than the anionic group-introduced fiber such as urea having a hydrogen bond property.

The fiber width of the fine fibrous cellulose after the defibration treatment applied to the step (A) is preferably 1 to 100 nm, more preferably 1 to 50 nm, still more preferably 1 to 25 nm. , 1 to 15 nm is more preferable, and 1 to 10 nm is particularly preferable.

Further, when the fine fibrous cellulose used in the step (A) is used as an aqueous dispersion having a concentration of 0.1% by mass and the nanofiber yield is calculated, the nanofiber yield is preferably 70% by mass or more. , 90% by mass or more, more preferably 93% by mass or more, and particularly preferably 96% by mass or more. The nanofiber yield may be 100% by mass. Here, the nanofiber yield is such that the fine fibrous cellulose dispersion having a concentration of 0.1% by mass is centrifuged at 12000 G for 10 minutes using a cooling high-speed centrifuge (Kokusan Co., Ltd., H-2000B). , It is a value measured from the cellulose concentration of the obtained supernatant liquid based on the following formula.
Nanofiber yield (% by mass) = cellulose concentration in supernatant (% by mass) /0.1 × 100

Further, when the fine fibrous cellulose used in the step (A) is used as an aqueous dispersion having a concentration of 0.2% by mass, the haze of the aqueous dispersion is preferably 20% or less, preferably 10% or less. It is more preferably 5.0% or less, and particularly preferably 3.0% or less. The haze of the aqueous dispersion may be 0%. Here, the haze of the aqueous dispersion of fine fibrous cellulose is a value measured according to JIS K 7136: 2000 using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute). At the time of measurement, a glass cell for liquid (manufactured by Fujiwara Seisakusho, MG-40, backlight path) having an optical path length of 1 cm is used. The zero point measurement is performed with ion-exchanged water placed in the same glass cell, and the dispersion liquid to be measured is allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours before measurement, and the liquid temperature of the dispersion liquid is measured. Is 23 ° C.

By setting the fiber width of the fine fibrous cellulose used in the step (A), the nanofiber yield of the fine fibrous cellulose dispersion and the haze within the above ranges, the fine fibrous cellulose obtained through the step (B) It is also possible to enhance the design when the slurry or rubber molded body is used.

<Substituent removal process>
The method for producing fine fibrous cellulose preferably includes a step (A) of removing at least a part of the substituent from the fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less. In the present specification, the step of removing at least a part of the substituent from the fine fibrous cellulose obtained by the above-mentioned step is also referred to as a substituent removal treatment step.

Examples of the substituent removing treatment step include a step of heat-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, a step of enzymatic treatment, a step of acid treatment, a step of alkali treatment and the like. These may be performed alone or in combination. Above all, the substituent removing treatment step is preferably a heat treatment step or an enzyme treatment step. Through the above treatment step, at least a part of the substituent is removed from the fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, and the amount of the substituent introduced is less than 0.5 mmol / g. Fibrous cellulose can be obtained.

The substituent removing treatment step is preferably performed in the form of a slurry. That is, the substituent removing treatment step is a step of heat-treating a slurry having a substituent and containing fine fibrous cellulose having a fiber width of 1000 nm or less, an enzyme treatment step, an acid treatment step, and an alkali treatment step. Etc. are preferable. By carrying out the substituent removing treatment step in the form of a slurry, it is possible to prevent the coloring substances generated by heating and the like during the substituent removing treatment and the residual of the acid, alkali, salt and the like added or generated. This makes it possible to suppress the coloring of the fine fibrous cellulose obtained through the step (B). Further, when the salt derived from the substituent removed after the substituent removal treatment is performed, the salt removal efficiency can be improved.

When the substituent removing treatment is performed on a slurry having a substituent and containing fine fibrous cellulose having a fiber width of 1000 nm or less, the concentration of the fine fibrous cellulose in the slurry is 0.05% by mass or more. It is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.2% by mass or more. The concentration of the fine fibrous cellulose in the slurry is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less. By setting the concentration of the fine fibrous cellulose in the slurry within the above range, the substituent removing treatment can be performed more efficiently. Further, by setting the concentration of the fine fibrous cellulose in the slurry within the above range, it is possible to prevent the coloring substances generated by heating during the substituent removal treatment and the residual of the acid, alkali, salt and the like added or generated. can. This makes it possible to suppress the coloring of the fine fibrous cellulose obtained through the step (B). Further, when the salt derived from the substituent removed after the substituent removal treatment is performed, the salt removal efficiency can be improved.

When the substituent removing treatment step is a step of heat-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, the heating temperature in the heat-treating step is preferably 40 ° C. or higher. , 50 ° C. or higher, more preferably 60 ° C. or higher. The heating temperature in the heat treatment step is preferably 250 ° C. or lower, more preferably 230 ° C. or lower, and even more preferably 200 ° C. or lower. Above all, when the substituent contained in the fine fibrous cellulose used in the substituent removal treatment step is a phosphoroxoic acid group or a sulfone group, the heating temperature in the heat treatment step is preferably 80 ° C. or higher, preferably 100 ° C. or higher. It is more preferable that the temperature is 120 ° C. or higher.

When the substituent removal treatment step is a heat treatment step, the heating device that can be used in the heat treatment step is not particularly limited, but is not particularly limited, but is a hot air heating device, a steam heating device, an electric heat heating device, a water heat heating device, and a thermal heating device. , Infrared heating device, Far infrared heating device, Microwave heating device, High frequency heating device, Stirring drying device, Rotating drying device, Disk drying device, Roll type heating device, Plate type heating device, Flow layer drying device, Band type drying device , A filtration drying device, a vibration flow drying device, an air flow drying device, and a vacuum drying device can be used. From the viewpoint of preventing evaporation, heating is preferably performed in a closed system, and from the viewpoint of further increasing the heating temperature, it is preferably performed in a pressure-resistant device or a container. The heat treatment may be a batch treatment, a batch continuous treatment, or a continuous treatment.

When the substituent removing treatment step is a step of enzymatically treating fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less, in the enzymatic treatment step, a phosphate ester hydrolyzing enzyme or a sulfate ester hydrolysis is performed. It is preferable to use an enzyme or the like.

In the enzyme treatment step, it is preferable to add the enzyme so that the enzyme activity is 0.1 nkat or more, more preferably 1.0 nkat or more, and 10 nkat or more to 1 g of fine fibrous cellulose. It is more preferable to add the enzyme so that it becomes. Further, it is preferable to add the enzyme so that the enzyme activity is 100,000 nkat or less with respect to 1 g of the fine fibrous cellulose, and it is more preferable to add the enzyme so that the enzyme activity is 50,000 nkat or less. More preferred. After adding the enzyme to the fine fibrous cellulose dispersion (slurry), it is preferable to carry out the treatment under the conditions of 0 ° C. or higher and lower than 50 ° C. for 1 minute or longer and 100 hours or shorter.

After the enzymatic reaction, a step of inactivating the enzyme may be provided. As a method of inactivating the enzyme, a method of adding an acid component or an alkaline component to the slurry treated with the enzyme to inactivate the enzyme, or raising the temperature of the slurry treated with the enzyme to 90 ° C. or higher to inactivate the enzyme. There is a method of deactivating.

When the substituent removing treatment step is a step of acid-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, the acid treatment step is an acid that can be used in the above-mentioned acid treatment step. It is preferred to add the compound to the slurry.

When the substituent removing treatment step is a step of alkali-treating fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less, the alkali-treating step is an alkali that can be used in the above-mentioned alkali-treating step. It is preferable to add the compound to the slurry.

In the substituent removal treatment step, it is preferable that the substituent removal reaction proceeds uniformly. In order to proceed the reaction uniformly, for example, the slurry containing fine fibrous cellulose may be stirred, or the specific surface area of the slurry may be increased. As a method of stirring the slurry, a mechanical share from the outside may be given, or self-stirring may be promoted by increasing the liquid feeding rate of the slurry during the reaction.

Spacer molecules may be added in the substituent removal treatment step. The spacer molecule penetrates between the adjacent fine fibrous celluloses, thereby acting as a spacer for providing a fine space between the fine fibrous celluloses. By adding such a spacer molecule in the substituent removing treatment step, aggregation of fine fibrous cellulose after the substituent removing treatment can be suppressed. This makes it possible to more effectively enhance the design and tensile properties of the molded product containing the fine fibrous cellulose.

The spacer molecule is preferably a water-soluble organic compound. Examples of the water-soluble organic compound include sugars, water-soluble polymers, urea and the like. Specific examples thereof include trehalose, urea, polyethylene glycol (PEG), polyethylene oxide (PEO), carboxymethyl cellulose, polyvinyl alcohol (PVA) and the like. In addition, as water-soluble organic compounds, alkyl methacrylate / acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide. , Xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seed, alginic acid, purulan, carrageenan, pectin, cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, starches such as amylose, glycerin , Diglycerin, polyglycerin, hyaluronic acid, metal salts of hyaluronic acid can also be used.

Further, a known pigment can be used as the spacer molecule. For example, kaolin (including clay), calcium carbonate, titanium oxide, zinc oxide, amorphous silica (containing colloidal silica), aluminum oxide, zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, Examples thereof include styrene-based plastic pigments, hydrotalcites, urea resin-based plastic pigments, and benzoguanamine-based plastic pigments.

<pH adjustment process>
When the substituent removing treatment step is performed in the form of a slurry, a step of adjusting the pH of the slurry containing the fine fibrous cellulose may be provided before the substituent removing treatment step. For example, when an anionic group is introduced into a cellulose fiber and the counterion of the anionic group is Na ⁺ , the slurry containing the fine fibrous cellulose after defibration shows weak alkalinity. When heating is performed in this state, monosaccharides, which are one of the coloring factors, may be generated due to the decomposition of cellulose. Therefore, it is preferable to adjust the pH of the slurry to 8 or less, and it is more preferable to adjust it to 6 or less. preferable. Further, since monosaccharides may be generated under acidic conditions as well, it is preferable to adjust the pH of the slurry to 3 or more, and more preferably to 4 or more.

Further, when the fine fibrous cellulose having a substituent is a fine fibrous cellulose having a phosphoric acid group, the phosphorus of the phosphate group is vulnerable to a nucleophilic attack from the viewpoint of improving the removal efficiency of the substituent. Is preferable. The vulnerable to nucleophilic attack is a state of neutralization degree 1 represented by cellulose-O-P (= O) (-O-H ⁺ ) ( ^{-O-Na +).} The pH of the slurry is preferably adjusted to 3 or more and 8 or less, and more preferably 4 or more and 6 or less.

The means for adjusting the pH is not particularly limited, and for example, an acid component or an alkaline component may be added to a slurry containing fine fibrous cellulose. The acid component may be either an inorganic acid or an organic acid, and examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. Examples of the organic acid include malic acid, acetic acid, citric acid, malic acid, lactic acid, adipic acid, sebacic acid, stearic acid, maleic acid, succinic acid, tartrate acid, fumaric acid, gluconic acid and the like. The alkaline component may be an inorganic alkaline compound or an organic alkaline compound. Examples of the inorganic alkaline compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, lithium hydrogencarbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, sodium hydrogencarbonate and the like. Examples of organic alkaline compounds include ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, and tetramethyl. Examples thereof include ammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4-aminopyridine and the like.

Further, in the pH adjusting step, an ion exchange treatment may be performed to adjust the pH. In the ion exchange treatment, a strongly acidic cation exchange resin or a weakly acidic ion exchange resin can be used. By treating with an appropriate amount of cation exchange resin for a sufficient time, a slurry containing fine fibrous cellulose having a desired pH can be obtained. Further, in the pH adjusting step, the addition of an acid component or an alkaline component may be combined with an ion exchange treatment.

<Salt removal treatment>
After the substituent removal treatment step, it is preferable to perform a substituent removal treatment for the removed substituent-derived salt. By removing the salt derived from the substituent, it becomes easy to obtain fine fibrous cellulose capable of suppressing coloring. The means for removing the salt derived from the substituent is not particularly limited, and examples thereof include a washing treatment. The washing treatment is performed by washing the fine fibrous cellulose aggregated in the substituent removing treatment with, for example, water or an organic solvent. From the viewpoint of more effectively suppressing yellowing, the washing treatment is preferably performed by filtration dehydration, centrifugal dehydration, or centrifugal separation.

(Step (B))
The method for producing fine fibrous cellulose includes a step (A) of removing at least a part of the substituent from the fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, and after the step (A). The step (B) for uniform dispersion processing may be included. The step (B) for uniform dispersion treatment is a step for uniform dispersion treatment of the fine fibrous cellulose obtained through the substituent removal treatment in step (A). The state in which the fine fibrous cellulose is uniformly dispersed in the step (B) means a state in which the fiber width of the fine fibrous cellulose is 100 nm or less. By going through the step (B), the fine fibrous cellulose has a number average fiber width of 100 nm or less, preferably 100 nm or less, even though the amount of the substituents introduced is as low as less than 0.5 mmol / g. , 50 nm or less can be easily set.

In the step (B) of uniform dispersion processing, for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, a twin-screw kneader, and a vibration mill. , A homomixer, an ultrasonic disperser or a beater under high speed rotation can be used. Among the uniform dispersion processing devices, it is more preferable to use a high-speed defibrator and a high-pressure homogenizer.

The treatment conditions in the step (B) for the uniform dispersion treatment are not particularly limited, but it is preferable to increase the maximum moving speed of the fine fibrous cellulose during the treatment and the pressure during the treatment. In the high-speed defibrator, the peripheral speed is preferably 20 m / sec or more, more preferably 25 m / sec or more, and further preferably 30 m / sec or more. The high-pressure homogenizer can be used more preferably than the high-speed defibrator because the maximum moving speed of the fine fibrous cellulose during the treatment and the pressure during the treatment are higher. In the high-pressure homogenizer treatment, the pressure at the time of treatment is preferably 1 MPa or more, more preferably 10 MPa or more, further preferably 50 MPa or more, and particularly preferably 100 MPa or more. Further, in the high-pressure homogenizer treatment, the pressure at the time of treatment is preferably 350 MPa or less, more preferably 300 MPa or less, still more preferably 250 MPa or less.

In the step (B), the above-mentioned spacer molecule may be newly added. By adding such a spacer molecule in the uniform dispersion treatment step of the step (B), uniform dispersion of the fine fibrous cellulose can be performed more smoothly.

(Manufacturing method of rubber composition)
The method for producing a rubber composition of the present invention includes a step of mixing a rubber component with the fine fibrous cellulose obtained in the above-mentioned step. The step of mixing the rubber component and the fine fibrous cellulose is preferably a step of mixing the rubber component and the fine fibrous cellulose dispersion, and is a step of kneading the rubber component and the fine fibrous cellulose dispersion. More preferred. In the step of mixing the rubber component and the fine fibrous cellulose, the rubber component is preferably in the state of rubber latex, and the step is preferably the step of kneading the rubber latex and the fine fibrous cellulose dispersion. The rubber component used in the step may be in a solid state, and in this case, the powdery granular rubber component may be mixed with the powdery granular fine fibrous cellulose.

In the step of mixing the rubber component and the fine fibrous cellulose, the fine fibrous cellulose may be in a solid state or may be in the state of a dispersion liquid dispersed in a dispersion medium. In this case, the dispersion medium is not particularly limited, but preferably contains water, and more preferably a solvent containing water as a main component. Examples of the organic solvent include dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), aniline, pyridine, quinoline, lutidine, acetonitrile, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and the like. Examples thereof include dioxane, ethanol, isopropanol and the like. Further, as the dispersion medium, a mixed solvent in which these organic solvents and water are mixed can also be used.

In the step of mixing the rubber component and the fine fibrous cellulose, when the fine fibrous cellulose dispersion liquid and the rubber component are mixed, the concentration of the fine fibrous cellulose dispersion liquid is preferably 0.1% by mass or more. It is more preferably 0.0% by mass or more, and further preferably 2.0% by mass or more. Further, the concentration of the fine fibrous cellulose dispersion liquid may be 3.0% by mass or more.

When the step of mixing the rubber component and the fine fibrous cellulose is the step of mixing the rubber component and the solid fine fibrous cellulose, the solid fine fibrous cellulose concentrates, for example, the fine fibrous cellulose dispersion. Obtained by doing. In this case, in the concentration step, a method of evaporating the dispersion medium, a method of concentrating with a flocculant, a spray drying method, a freeze-drying method, a vacuum drying method, a replacement method with an inactivating gas such as nitrogen or argon, etc. are mentioned. Can be done.

The water content in the solid fine fibrous cellulose is preferably 25% by mass or less, more preferably 20% by mass or less, and more preferably 15% by mass or less, based on the total mass of the solid body. It is more preferable to have. By setting the water content in the solid fine fibrous cellulose within the above range, the fine fibrous cellulose can be easily uniformly dispersed in the rubber component.

When the step of mixing the rubber component and the fine fibrous cellulose is the step of mixing the rubber latex and the fine fibrous cellulose dispersion, the step of mixing the rubber latex and the fine fibrous cellulose dispersion includes a homogenizer or a disperser. A known mixer such as Claremix can be used. In this case, the stirring frequency of the mixer is preferably 1000 to 10000 rpm. When the step of mixing the rubber component and the fine fibrous cellulose is the step of mixing the powdery granular rubber component and the powdery granular fine fibrous cellulose, the powdery granular rubber component and the powdery granular fine fibrous cellulose are mixed. A mixer such as an open roll, a kneader, a rubbery mixer, a plast mill, or a screw press can be used for mixing.

(Molded body)
The present invention also relates to a molded body obtained by molding the above-mentioned rubber composition. In the present specification, the rubber component contained in the rubber composition is a pre-crosslinking raw material (a raw material in which a crosslinked structure is not substantially formed by vulture or the like), and is used for forming solid rubber such as synthetic rubber and natural rubber. In the case of the raw rubber, latex or rubber solution to be obtained, when the molded product is molded, a crosslinked structure is formed by the rubber composition under the crosslinking reaction conditions such as heating. In this case, the crosslinking reaction method is not particularly limited, and a known crosslinking method can be applied. When molding the molded product, the uncrosslinked rubber composition may be crosslinked after molding, and after a semi-crosslinked rubber is once obtained from the uncrosslinked rubber composition through a preliminary cross-linking step or the like, the semi-crosslinked rubber may be obtained. Further, this cross-linking may be performed. When the rubber component contained in the rubber composition is synthetic rubber or natural rubber having a crosslinked structure, the molded product is molded by heat molding or heat pressure molding of the rubber composition. In this case, the rubber composition refers to the one before heat molding or heat pressure molding. Further, the molded body may be formed by irradiating the rubber composition with ionizing radiation, or is formed by compression molding, injection molding, inflation molding, press-fit molding or extrusion molding of the rubber composition. There may be. The molding conditions are appropriately adjusted depending on the rubber component species and the like contained in the rubber composition.

The heating temperature at the time of heat molding or heat pressure molding of the rubber composition is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 140 ° C. or higher. The heating temperature is preferably 250 ° C. or lower. By heating under the above conditions, a crosslinked structure by vulcanization or the like can be sufficiently formed.

The molded product may be in the form of pellets, in the form of strands, or in the form of filaments. When the molded product is in the form of pellets, the molten rubber composition may be extruded into a strand shape, cooled and cut to form the molded product. When the rubber composition contains a foaming agent, the molded product may be a foamed product, and foaming also occurs at the same time as molding, so that a molded product having bubbles inside can be obtained.

The molded body is preferably a sheet-shaped molded body. In this case, the YI value of the molded product is preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less. The lower limit of the YI value of the molded product is not particularly limited, but is preferably 0.1 or more. Here, the YI value of the molded product is a YI value measured in accordance with JIS K 7373: 2006. As the YI value measuring device, for example, Color Cutei (manufactured by Suga Test Instruments Co., Ltd.) can be used.

(Use)
The use of the rubber composition of the present invention is not particularly limited, but is not limited to, for example, applications such as substrates for electronic devices, members of home appliances, window materials for various vehicles and buildings, interior materials, exterior materials, packaging materials, and the like. Can be used for. It can also be used for light-transmitting substrates such as various display devices and various solar cells.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the specific examples shown below.

<Manufacturing example 1>
[Phosphorylation]
Hardwood pulp (dry sheet) made by Oji Paper was used as the raw material pulp. The raw material pulp was subjected to phosphorylation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated with a hot air drying device at 165 ° C. for 250 seconds to introduce a phosphate group into the cellulose in the pulp to obtain a phosphorylated pulp.

[Washing process]
Then, the obtained phosphorylated pulp was washed. The cleaning treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. gone. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

[Neutralization treatment]
Next, the phosphorylated pulp after washing was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated to obtain a phosphorylated pulp that had been neutralized. Next, the phosphorylated pulp after the neutralization treatment was subjected to the above washing treatment.

The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption ^{of the phosphate group based on P = O was observed near 1230 cm-1} , and it was confirmed that the phosphate group was added to the pulp. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

[Defibration treatment]
Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a high-pressure homogenizer (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. The amount of the first dissociated acid (amount of phosphoric acid group) measured by the measuring method described in the measurement of [amount of phosphoroxo acid group] described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

<Manufacturing example 2>
After the [neutralization treatment], a fine fibrous cellulose dispersion containing phosphorylated pulp and fine fibrous cellulose was obtained in the same manner as in Production Example 1 except that the following nitrogen removal treatment was performed.

[Nitrogen removal treatment]
Ion-exchanged water was added to the phosphorylated pulp to prepare a slurry having a solid content concentration of 4% by mass. A 48% by mass sodium hydroxide aqueous solution was added to the slurry to adjust the pH to 13.4, and the slurry was heated at a liquid temperature of 85 ° C. for 1 hour. Then, this pulp slurry is dehydrated, and the pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp is stirred so that the pulp is uniformly dispersed, and filtered and dehydrated. The excess sodium hydroxide was removed by repeating. When the electrical conductivity of the filtrate became 100 μS / cm or less, the end point of removal was set.

The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption ^{of the phosphate group based on P = O was observed near 1230 cm-1} , and it was confirmed that the phosphate group was added to the pulp. Further, it was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained the cellulose type I crystal. The amount of phosphate groups (first dissociated acid amount, strongly acidic group amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.35 mmol / g. The total amount of dissociated acid was 2.30 mmol / g.

<Manufacturing example 3>
[Subphosphorylation treatment]
The same operation as in Production Example 1 was carried out except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate in the phosphorylation treatment, and fine particles containing phosphorous oxide pulp and fine fibrous cellulose were carried out. A fibrous cellulose dispersion was obtained.

The infrared absorption spectrum of the subphosphorylated pulp thus obtained was measured using FT-IR. As a result, ^{absorption based on P = O of the phosphonic acid group, which is a metamorphic form of the phosphorous acid group, was observed near 1210 cm-1} , and the phosphorous acid group (phosphonic acid group) was added to the pulp. Was confirmed. Further, it was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained the cellulose type I crystal. The first dissociative acid amount (subphosphate group amount) measured by the measurement method described in [Measurement of Phosphoric Acid Group Amount] described later is 1.51 mmol / g, and the total dissociative acid amount is 1. It was 54 mmol / g.

<Manufacturing example 4>
[Sulfation treatment]
In the phosphorylation treatment, 38 parts by mass of amide sulfuric acid (sulfamic acid) was used instead of ammonium dihydrogen phosphate, and the same operation as in Production Example 1 was carried out except that the heating time was extended to 19 minutes. A fine fibrous cellulose dispersion containing fine fibrous cellulose was obtained.

The infrared absorption spectrum of the sulfated pulp thus obtained was measured using FT-IR. As a result, ^{absorption based on a sulfate group (sulfone group) was observed in the vicinity of 1220-1260 cm-1} , and it was confirmed that a sulfate group (sulfone group) was added to the pulp. Further, it was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained the cellulose type I crystal. The amount of sulfone groups measured by the measuring method described in [Measurement of Sulfone Group Amount] described later was 1.12 mmol / g.

<Manufacturing example 5>
[TEMPO oxidation treatment]
100 parts by mass (absolute dry mass) of the raw material pulp, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), 10 parts by mass of sodium bromide, and 10000 parts by mass of water. Dispersed in. A 13 parts by mass sodium hypochlorite aqueous solution was added to the obtained dispersion liquid so as to be 1.9 mmol with respect to 1.0 g of pulp, and the reaction was started. During the reaction, a 0.5 N aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change was observed in the pH.

[Washing process]
Then, the obtained TEMPO oxide pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of TEMPO oxide pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. gone. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

[Counterion exchange processing]
Next, the TEMPO oxide pulp after washing was subjected to a counter ion exchange treatment as follows. First, the TEMPO oxidized pulp was diluted with 10 L of ion-exchanged water, 1N hydrochloric acid was added so that the obtained pulp dispersion had a pH of 2, and the mixture was stirred for 30 minutes. As a result, the carboxy group in the TEMPO oxide pulp was converted from the Na type to the acid type. Next, the TEMPO oxide pulp slurry was dehydrated to obtain an acid-type TEMPO oxide pulp subjected to counterion exchange treatment. Next, the above-mentioned washing treatment was performed on the TEMPO oxide pulp after the counterion exchange treatment.

[Defibration treatment]
Ion-exchanged water was added to the obtained acid-type TEMPO-oxidized pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) 6 times at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. The amount of carboxy group measured by the measuring method described in [Measurement of carboxy group amount] described later was 0.65 mmol / g.

<Manufacturing example 6>
The same operation as in Production Example 1 was carried out except that the following zantate treatment was performed instead of the phosphorylation treatment to obtain a fine fibrous cellulose dispersion containing the zantate pulp and fine fibrous cellulose.

[Zantate processing]
To 100 parts by mass (absolute dry mass) of raw material pulp (dissolving pulp of broadleaf tree made by Oji Paper (dry sheet)), 2500 parts by mass of 8.5 mass% sodium hydroxide aqueous solution was added, and the mixture was stirred at room temperature for 3 hours. Alkaline treatment was performed. The pulp after the alkali treatment was separated into solid and liquid by centrifugation (filter cloth 400 mesh, 3000 rpm for 5 minutes) to obtain a dehydrated product of alkaline cellulose. To 10 parts by mass (absolute dry mass) of the obtained alkaline cellulose, 3.5 parts by mass of carbon disulfide was added, and the sulfurization reaction was allowed to proceed at room temperature for 4.5 hours to carry out a zantate treatment.

By X-ray diffraction, it was confirmed that the obtained fine fibrous cellulose maintained the cellulose type I crystal. The amount of zantate group measured by the measuring method described in [Measurement of Zantate Group Amount] described later was 1.73 mmol / g.

<Manufacturing example 7>
Ion-exchanged water was added to the raw material pulp (hardwood pulp (dry sheet) made by Oji Paper Co., Ltd.) to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated 30 times at a pressure of 200 MPa with a wet atomizer (Sugino Machine Limited, Starburst) to obtain a cellulose dispersion containing coarse fibrous cellulose having a fiber width of more than 1000 nm.

<Example 1>
[Substituent removal treatment (high temperature heat treatment)]
A 20% by mass citric acid aqueous solution was added to the fine fibrous cellulose dispersion obtained in Production Example 1 to adjust the pH of the dispersion to 5.5. The obtained slurry was placed in a pressure-resistant container and heated at a liquid temperature of 160 ° C. for 15 minutes until the amount of phosphoric acid groups reached 0.08 mmol / g. The formation of fine fibrous cellulose aggregates was confirmed by this operation.

[Washing of slurry after removal of substituents]
The slurry was washed by repeating the operation of adding ion-exchanged water in the same amount as the slurry to make a slurry having a solid content concentration of about 1% by mass, stirring the slurry, and then filtering and dehydrating the slurry. .. When the electrical conductivity of the filtrate became 10 μS / cm or less, ion-exchanged water was added again to make a slurry of about 1% by mass, and the slurry was allowed to stand for 24 hours. The operation of further filtering and dehydrating was repeated from there, and the time when the electrical conductivity of the filtrate became 10 μS / cm or less was set as the washing end point. Ion-exchanged water was added to the obtained fine fibrous cellulose aggregate to remove substituents, and then a slurry was obtained. The solid content concentration of this slurry was 1.7% by mass. The pH of the washed slurry was 5.5 when the solid content concentration was 1.0% by mass. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 26 nm, and the ratio of the fiber width of 10 nm or less was 42%.
The proportion of fine fibrous cellulose having a fiber width of 10 nm or less was calculated by the following formula.
Percentage of fine fibrous cellulose with fiber width of 10 nm or less (%) = (Number of fine fibrous cellulose with fiber width of 10 nm or less / Number of total fibrous cellulose) × 100

[Preparation of rubber composition containing fine fibrous cellulose]
A rubber composition containing fine fibrous cellulose was obtained by the method described below.

[Adjustment of masterbatch]
Natural rubber latex (manufactured by Reditex Co., Ltd., NRLATEX, concentration 60) was prepared by using a slurry after removing substituents so that the absolute dry mass of the substituent-removed fine fibrous cellulose was 5 parts by mass with respect to 100 parts by mass of the solid content of the natural rubber latex. %), And the mixture was stirred and dispersed at 4000 rpm for 5 minutes using a homogenizer (T18 digital ULTRA-TURRAX manufactured by IKA). A natural rubber masterbatch was obtained by adding 5% by mass formic acid to the obtained mixed solution to coagulate it, washing it with water, and drying the slurry at 40 ° C.

[Preparation of compound]
Zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), vulcanization accelerator (Sanshin Chemical Industries, Ltd.) in the master batch ), Sunseller CM) is added so as to have the composition shown in Table 2, mixed by a twin-screw extrusion kneader (HK25D (L / D 41) manufactured by Parker Corporation) at a cylinder temperature of 70 ° C, and compound (rubber). Composition) was obtained.

[Vulcanization process]
The obtained compound was placed in a mold and press-heated at 150 ° C. to prepare a crosslinked rubber sheet (molded product) having a thickness of 2 mm.

<Example 2>
Substituent removal treatment was carried out at a liquid temperature of 160 ° C. for 40 minutes in the same manner as in Example 1 except that the amount of the phosphate group reached 0.05 mmol / g. A fibrous cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 27 nm, and the ratio of the fiber width of 10 nm or less was 41%.

<Example 3>
Substituent removal treatment was carried out at a liquid temperature of 150 ° C. for 15 minutes in the same manner as in Example 1 except that the amount of the phosphate group was 0.21 mmol / g. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 25 nm, and the ratio of the fiber width of 10 nm or less was 43%.

<Example 4>
Substituent removal treatment was carried out at a liquid temperature of 140 ° C. for 20 minutes in the same manner as in Example 1 except that the amount of the phosphate group was 0.40 mmol / g. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 22 nm, and the ratio of the fiber width of 10 nm or less was 48%.

<Example 5>
Substitution after removing the substituent is substituted in the same manner as in Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 2 is used instead of the fine fibrous cellulose dispersion obtained in Production Example 2. A rubber composition containing fine fibrous cellulose from which groups were removed and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 26 nm, and the ratio of the fiber width of 10 nm or less was 42%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 6>
Substitution after removing the substituent is substituted in the same manner as in Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 3 is used instead of the fine fibrous cellulose dispersion obtained in Production Example 3. A rubber composition containing fine fibrous cellulose from which groups were removed and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 28 nm, and the ratio of the fiber width of 10 nm or less was 40%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 7>
Substitution after removing the substituent is substituted in the same manner as in Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 4 is used instead of the fine fibrous cellulose dispersion obtained in Production Example 4. A rubber composition containing fine fibrous cellulose from which groups were removed and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 29 nm, and the ratio of the fiber width of 10 nm or less was 40%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 8>
Examples except that the substituent removal treatment was carried out using the fine fibrous cellulose dispersion obtained in Production Example 5 at a liquid temperature of 150 ° C. for 300 minutes until the amount of carboxy groups became 0.24 mmol / g. After removing the substituent, a slurry, a fine fibrous cellulose-containing rubber composition from which the substituent was removed, and a rubber sheet were obtained in the same manner as in 1. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 27 nm, and the ratio of the fiber width of 10 nm or less was 41%.

<Example 9>
Instead of the fine fibrous cellulose dispersion obtained in Production Example 1, the fine fibrous cellulose dispersion obtained in Production Example 6 was used. Further, instead of the [substituent removal treatment (high temperature heat treatment)], the [substituent removal treatment (low temperature heat treatment)] described later was performed. In the same manner as in Example 1, a slurry after removing the substituent, a rubber composition containing fine fibrous cellulose from which the substituent was removed, and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 27 nm, and the ratio of the fiber width of 10 nm or less was 40%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 8.3 when the solid content concentration was 1.0% by mass.

[Substituent removal treatment (low temperature heat treatment)]
The obtained fine fibrous cellulose dispersion was heated at a liquid temperature of 40 ° C. for 45 minutes without a pH adjustment step, and heated until the amount of zantate groups reached 0.08 mmol / g.

<Example 10>
Following the [cleaning treatment of the slurry after removing the substituent], the slurry and the slurry after removing the substituent are removed in the same manner as in Example 1 except that the following [uniform dispersion treatment of the slurry after removing the substituent] is performed. A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 98%.

[Uniform dispersion treatment of slurry after removal of substituents]
Ion-exchanged water was added to the obtained slurry after removing the substituents to prepare a slurry having a solid content concentration of 1.0% by mass. This slurry had a pH of 5.5. The slurry was treated three times at a pressure of 200 MPa with a wet atomizer (Sugino Machine Limited, Starburst) to obtain a slurry after removing the substituents containing the fine fibrous cellulose for removing the substituents. The number average fiber diameter of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 98%.

<Example 11>
Substituent-removed slurry, substituent-removed fine fibers in the same manner as in Example 6 except that [substituent-removed slurry cleaning treatment] was followed by [substituent-removed slurry uniform dispersion treatment]. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 91%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 12>
Substituent-removed slurry, substituent-removed fine fiber in the same manner as in Example 7 except that [Substituent-removed slurry cleaning treatment] was followed by [Substituent-removed slurry uniform dispersion treatment]. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 91%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 13>
Substituent-removed slurry, substituent-removed fine fibers in the same manner as in Example 8 except that [substituent-removed slurry cleaning treatment] was followed by [substituent-removed slurry uniform dispersion treatment]. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 5 nm, and the ratio of the fiber width of 10 nm or less was 93%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 8.3 when the solid content concentration was 1.0% by mass.

<Example 14>
Substituent-removed slurry, substituent-removed fine fibers in the same manner as in Example 9 except that [substituent-removed slurry cleaning treatment] was followed by [substituent-removed slurry uniform dispersion treatment]. A cellulose-containing rubber composition and a rubber sheet were obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 91%. The pH of the slurry subjected to [cleaning treatment of the slurry after removing the substituent] was 5.5 when the solid content concentration was 1.0% by mass.

<Example 15>
[Powdering of slurry after removing substituents]
After removing the substituents, the obtained slurry was dried in an environment of 30 ° C. and a relative humidity of 15% until the water content reached 85% by mass. Then, it was pulverized at 20,000 rpm using a lab miller (LM-PLUS, manufactured by Osaka Chemical Co., Ltd.) to obtain fine fibrous cellulose powder from which substituents were removed.

[Preparation of masterbatch]
Substituent-removed fine fibrous cellulose so that the absolute dry mass of the substituent-removed fine fibrous cellulose is 5 parts by mass with respect to 100 parts by mass of the raw material before cross-linking of ethylene-propylene-diene copolymer rubber (hereinafter, EPDM). The powder was added to an ethylene-propylene-diene copolymer rubber (EP104E, manufactured by JSR Co., Ltd.) and pre-kneaded using a laboplast mill (3S150, manufactured by Toyo Seiki Seisakusho Co., Ltd.). There, silica (manufactured by Tokuyama Co., Ltd., Tokusir U), zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), A vulcanization accelerator (Sunseller CM (manufactured by Sanshin Chemical Industries, Ltd.)) was added so as to have the composition shown in Table 3, and kneaded for 15 minutes to obtain a master batch.

[Preparation of compound]
The masterbatch was compounded by a twin-screw extruder (HK25D (L / D 41) manufactured by Parker Corporation). The obtained compound was left at room temperature for 12 hours or more.

[Vulcanization process]
The obtained compound was placed in a mold and compression molded at 180 ° C. for 10 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Example 16>
The same operation as in Example 15 was carried out except that the slurry after removing the substituents obtained in Example 2 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 17>
The same operation as in Example 15 was carried out except that the slurry after removing the substituents obtained in Example 6 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 18>
The same operation as in Example 15 was carried out except that the slurry after removing the substituents obtained in Example 7 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 19>
The same operation as in Example 15 was carried out except that the slurry after removing the substituents obtained in Example 8 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 20>
[Adjustment of masterbatch]
The slurry after removing the substituents obtained in Example 1 so as to have an absolute dry mass of 5 parts by mass of the fine fibrous cellulose from which the substituents have been removed with respect to 100 parts by mass of the solid content of the raw material before cross-linking of the silicone rubber was added to the silicone rubber (silicon rubber). It was added to KE-931-U manufactured by Shin-Etsu Chemical Co., Ltd., and pre-kneaded using a laboplast mill (3S150 manufactured by Toyo Seiki Seisakusho Co., Ltd.). Silica ((Tokuyama Corporation, Tokusir U)) and a curing agent (Shin-Etsu Chemical Co., Ltd., C-8) are added thereto so as to have the composition shown in Table 4, and mixed for 5 minutes. I got a masterbatch.

[Preparation of compound]
The masterbatch was compounded by a twin-screw extruder (HK25D (L / D 41) manufactured by Parker Corporation). The obtained compound was left at room temperature for 12 hours or more.

[Vulcanization process]
The obtained compound was placed in a mold and compression molded at 180 ° C. for 10 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Example 21>
The same operation as in Example 20 was carried out except that the slurry after removing the substituents obtained in Example 2 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 22>
The same operation as in Example 20 was carried out except that the slurry after removing the substituents obtained in Example 6 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 23>
The same operation as in Example 20 was carried out except that the slurry after removing the substituents obtained in Example 7 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 24>
The same operation as in Example 20 was carried out except that the slurry after removing the substituents obtained in Example 8 was used to obtain a rubber composition containing fine fibrous cellulose containing the substituents and a rubber sheet.

<Example 25>
[Preparation of masterbatch]
Styrene-butadiene copolymer rubber latex (Nipol LX112, manufactured by Nippon Zeon Co., Ltd., hereinafter SBR) was carried out so that the absolute dry mass of the substituent-removed fine fibrous cellulose was 5 parts by mass with respect to 100 parts by mass of the solid content. After removing the substituents obtained in Example 1, the slurry was mixed and stirred and dispersed at 4000 rpm for 15 minutes using a homogenizer (manufactured by IKA, T18 digital ULTRA-TURRAX). The aqueous suspension was dried overnight in a heating oven at 70 ° C. to give a dried product. The dried product was heated in an oven at 120 ° C. for 30 minutes to prepare a masterbatch.

[Preparation of compound]
Zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), vulcanization accelerator (Sunseller NS-G (3)) in the master batch. Shin Kagaku Kogyo Co., Ltd.)) was added so as to have the composition shown in Table 5, and kneaded for 15 minutes using Labplast Mill (3S150 manufactured by Toyo Seiki Seisakusho Co., Ltd.) to obtain an uncrosslinked compound. Obtained.

[Vulcanization process]
The obtained compound was placed in a mold and crosslinked by pressing at 180 ° C. for 10 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Example 26>
The same operation as in Example 25 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 2, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 27>
The same operation as in Example 25 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 6, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 28>
The same operation as in Example 25 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 7, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 29>
The same operation as in Example 25 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 8, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 30>
[Preparation of masterbatch]
Obtained in Example 1 so that the absolute dry mass of the substituent-removed fine fibrous cellulose is 5 parts by mass with respect to 100 parts by mass of the solid content of acrylonitrile-butadiene rubber polymer latex (Nipol511A, manufactured by Nippon Zeon Corporation, hereinafter NBR). After removing the substituents, the slurry was mixed and stirred and dispersed at 4000 rpm for 15 minutes using a homogenizer (T18 digital ULTRA-TURRAX manufactured by IKA). The aqueous suspension was dried overnight in a heating oven at 70 ° C. to give a dried product. The dried product was heated in an oven at 120 ° C. for 30 minutes to prepare a masterbatch.

[Preparation of compound]
Zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), vulcanization accelerator (Sunseller NOB (Sanshin Kagaku)) in the master batch (Manufactured by Kogyo Co., Ltd.)) was added so as to have the composition shown in Table 6, and kneaded using a laboplast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd., 3S150) for 15 minutes to obtain an uncrosslinked compound. ..

[Crosslinking process]
The obtained compound was placed in a mold and crosslinked by pressing at 180 ° C. for 10 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Example 31>
The same operation as in Example 30 was carried out except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 2, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 32>
The same operation as in Example 30 in which the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 6 was carried out to carry out the same operation as in Example 30 to remove the substituents and the fibrous cellulose-containing rubber composition. Obtained a rubber sheet.

<Example 33>
The same operation as in Example 30 was carried out except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 7, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 34>
The same operation as in Example 30 was carried out except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 8, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 35>
In the same manner as in Example 15, after performing [uniform dispersion powder treatment of the slurry after removing the substituent], a crosslinked rubber sheet was prepared by the following method.

[Preparation of masterbatch]
Substituents so that the absolute dry mass of the substituent-removed fine fibrous cellulose is 5 parts by mass with respect to 100 parts by mass of the solid content of the raw material before cross-linking of butadiene rubber (Nipol BR1220, manufactured by Nippon Zeon Corporation, hereinafter BR). The fine fibrous cellulose powder to be removed was added and kneaded using a laboplast mill (3S150 manufactured by Toyo Seiki Seisakusho Co., Ltd.). There, zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), vulcanization accelerator (Sunseller NS-G (Sanshin)). Chemical Industry Co., Ltd.)) was added so as to have the composition shown in Table 7, and kneaded with a laboplast mill (3S150 manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 15 minutes to obtain a master batch.

[Preparation of compound]
Zinc oxide (manufactured by Wako Pure Chemical Industries, Ltd.), stearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), sulfur (manufactured by Wako Pure Chemical Industries, Ltd.), vulcanization accelerator (Sunseller NOB (Sanshin Kagaku)) in the master batch (Manufactured by Kogyo Co., Ltd.)) was added so as to have the composition shown in Table 7, and kneaded using a laboplast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd., 3S150) for 15 minutes to obtain an uncrosslinked compound. ..

[Crosslinking process]
The obtained compound was placed in a mold and crosslinked by pressing at 180 ° C. for 10 minutes to prepare a crosslinked rubber sheet having a thickness of 2 mm.

<Example 36>
The same operation as in Example 35 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 2, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 37>
The same operation as in Example 35 was carried out except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 6, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 38>
The same operation as in Example 35 was carried out except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 7, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Example 39>
The same operation as in Example 35 was performed except that the slurry after removing the substituents obtained in Example 1 was changed to the slurry after removing the substituents obtained in Example 8, and the composition of the rubber containing fine fibrous cellulose containing the substituents was removed. A thing and a rubber sheet were obtained.

<Comparative Example 1>
In [Preparation of Fine Fibrous Cellulose-Containing Rubber Composition], [Fine] described in Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 2>
A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained in the same manner as in Comparative Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 3 was used. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 3>
A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained in the same manner as in Comparative Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 4 was used. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 4>
A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained in the same manner as in Comparative Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 5 was used. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 4 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 5>
A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained in the same manner as in Comparative Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 6 was used. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 5 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 6>
In [Preparation of Fine Fibrous Cellulose-Containing Rubber Composition], [Fine] described in Example 15 except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 7>
In [Preparation of Fine Fibrous Cellulose-Containing Rubber Composition], [Fine] described in Example 20 except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 8>
A rubber composition containing fine fibrous cellulose and a rubber sheet were obtained in the same manner as in Comparative Example 1 except that the fine fibrous cellulose dispersion obtained in Production Example 7 was used.

<Comparative Example 9>
In [Preparation of Fine Fibrous Cellulose-Containing Rubber Composition], [Fine] described in Example 25, except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 10>
In [Preparation of Fine Fibrous Cellulose-Containing Rubber Composition], [Fine] described in Example 30 except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

<Comparative Example 11>
In [Preparation of a rubber composition containing fine fibrous cellulose], the [fine fibrous cellulose dispersion] described in Example 35 is described except that the fine fibrous cellulose dispersion obtained in Production Example 1 was used instead of the slurry after removing the substituent. Preparation of fibrous cellulose-containing rubber composition] was carried out to obtain a fine fibrous cellulose-containing rubber composition and a rubber sheet. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of fiber width] described later was 3 nm, and the ratio of the fiber width of 10 nm or less was 99%.

[evaluation]
The slurries, rubber compositions and rubber sheets obtained in the above Examples and Comparative Examples were evaluated by the following methods.

[Measurement of phosphorus oxo acid group amount]
In measuring the amount of phosphorous acid group (phosphoric acid group or phosphorous acid group amount), first, ion-exchanged water is added to the target fine fibrous cellulose to prepare a slurry having a solid content concentration of 0.2% by mass. did. The obtained slurry was treated with an ion exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 is added to the fine fibrous cellulose-containing slurry, and the mixture is shaken for 1 hour. This was done by pouring onto a mesh with an opening of 90 μm to separate the resin and the slurry.
In the titration using alkali, the pH value indicated by the slurry is changed while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose-containing slurry treated with the ion exchange resin every 5 seconds. Was performed by measuring. Titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 1). The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point was divided by the solid content (g) in the slurry to be titrated, and the value was defined as the amount of phosphoroxo acid groups (mmol / g).

[Measurement of sulfone group amount]
The amount of sulfone groups was measured as follows. The fine fibrous cellulose was frozen in a freezer and then dried in a freeze-dryer (FreeZone manufactured by Loveconco) for 3 days. The obtained freeze-dried product was pulverized at a rotation speed of 20,000 rpm for 60 seconds using a hand mixer (manufactured by Osaka Chemical Co., Ltd., Lab Miller PLUS) to form a powder. The sample after freeze-drying and pulverization treatment was decomposed by heating under pressure using nitric acid in a closed container. Then, it was diluted appropriately and the amount of sulfur was measured by ICP-OES. The value calculated by dividing by the absolute dry mass of the fine fibrous cellulose tested was taken as the amount of sulfone groups (unit: mmol / g).

[Measurement of carboxy group amount]
The amount of carboxy group of the fine fibrous cellulose is a fibrous cellulose prepared by diluting the fine fibrous cellulose dispersion containing the target fine fibrous cellulose with ion-exchanged water so that the content is 0.2% by mass. The contained slurry was treated with an ion exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 is added to the above fibrous cellulose-containing slurry, and the mixture is shaken for 1 hour. This was done by pouring onto a mesh with an opening of 90 μm to separate the resin and the slurry.
In the titration using alkali, 50 μL of 0.1 N sodium hydroxide aqueous solution is added to the fibrous cellulose-containing slurry treated with an ion exchange resin once every 30 seconds to obtain the electrical conductivity of the slurry. This was done by measuring the change in value. For the carboxy group amount (mmol / g), the alkali amount (mmol) required in the region corresponding to the first region shown in FIG. 2 of the measurement results is divided by the solid content (g) in the slurry to be titrated. Calculated.

[Measurement of Zantate group amount]
The amount of zantate group was measured by the Bredee method. Specifically, 40 mL of saturated ammonium chloride solution was added to 1.5 parts by mass (absolute dry mass) of fibrous cellulose, mixed well while crushing the sample with a glass rod, left for about 15 minutes, and then GFP filter paper (ADVANTEC). It was filtered with GS-25) manufactured by GS-25) and thoroughly washed with a saturated ammonium chloride solution. The sample was placed in a 500 mL tall beaker together with the GFP filter paper, 50 mL of 0.5 M sodium hydroxide solution (5 ° C.) was added, and the mixture was stirred. After leaving for 15 minutes, a phenolphthalein solution was added until the solution turned pink, and then 1.5 M acetic acid was added, and the point at which the solution turned from pink to colorless was defined as a neutralization point. After neutralization, 250 mL of distilled water was added and stirred well, and 10 mL of 1.5 M acetic acid and 10 mL of 0.05 mol / L iodine solution were added using a whole pipette. This solution was titrated with a 0.05 mol / L sodium thiosulfate solution. The amount of zantate group was calculated from the following formula from the titration amount of sodium thiosulfate and the absolute dry mass of fibrous cellulose.
Zantate group amount (mmol / g) = (0.05 × 10 × 2-0.05 × sodium thiosulfate titration (mL)) / 1000 / Absolute dry mass of fibrous cellulose (g)

[Measurement of fiber width]
The fiber width of the fibrous cellulose was measured by the following method. Each fibrous cellulose dispersion was diluted with water so that the concentration of cellulose was 0.01% by mass or more and 0.1% by mass or less, and cast onto a hydrophilized carbon film-coated grid. After drying this, it was stained with uranyl acetate and observed with a transmission electron microscope (TEM, manufactured by JEOL Ltd., JEOL-2000EX). At that time, an axis having an arbitrary vertical and horizontal image width was assumed in the obtained image, and the magnification was adjusted so that 20 or more fibers intersected the axis. After obtaining an observation image satisfying this condition, two random axes in each of the vertical and horizontal directions were drawn for this image, and the fiber width of the fibers intersecting the axes was visually read. Three non-overlapping observation images were taken for each dispersion, and the value of the fiber width of the fibers intersecting each of the two axes was read (20 or more × 2 × 3 = 120 or more). The number average fiber width was calculated from the fiber width obtained in this way. However, only in Comparative Example 8 using Production Example 7, the obtained dispersion was diluted with water so that the concentration of cellulose was 0.01% by mass or more and 0.1% by mass or less, and cast onto glass. It was observed with a scanning electron microscope (SEM).

[Measurement of nitrogen content]
The total amount of free nitrogen contained in the fibrous cellulose and the fibrous cellulose dispersion was measured by the method described below. Each dispersion was adjusted to a solid content concentration of 1% by mass and decomposed by the Kjeldahl method (JIS K 0102: 2016 44.1). After decomposition, the amount of ammonium ions (mmol) was measured by cation chromatography and divided by the amount of cellulose (g) used for the measurement to calculate the nitrogen content (mmol / g).

[Tensile strength measurement]
The rubber sheets obtained in Examples and Comparative Examples were subjected to a tensile test according to JIS K 6251: 2017 "Vulcanized rubber and thermoplastic rubber-How to determine tensile properties", and the breaking stress was measured. From the measured values, the tensile strength index was calculated using the following formula. The control rubber sheet is a rubber sheet produced without blending fibrous cellulose. For example, in Example 1, the rubber sheet produced by performing the operations after [Preparation of masterbatch] using only natural rubber latex without using the slurry after removing the substituent becomes the control rubber sheet.
Tensile strength index = breaking stress of rubber sheet / breaking stress of control rubber sheet x 100
Then, the obtained tensile strength index was evaluated in the following five stages A to E.
A: Tensile strength index is 120 or more and B: Tensile strength index is 110 or more and less than 120 C: Tensile strength index is 100 or more and less than 110 D: Tensile strength index is 90 or more and less than 100 E: Tensile strength index is less than 90

[Design evaluation]
The size and quantity of the rubber sheet lumps of the 50 mm × 50 mm example and the comparative example were evaluated on the following five stages A to E.
A: The number of lumps with an area circle equivalent diameter of 1 mm or more is 10 or less B: The number of lumps with an area circle equivalent diameter of 1 mm or more is 11 to 20 C: The number of lumps with an area circle equivalent diameter of 1 mm or more is 21 ~ 30 D: The number of lumps with an area circle equivalent diameter of 1 mm or more is 31-40 E: The number of lumps with an area circle equivalent diameter of 1 mm or more is 41 or more

[Coloring evaluation]
In accordance with JIS K 7373: 2006, the yellowness of the rubber sheets of Examples and Comparative Examples was measured using Color Cutei (manufactured by Suga Test Instruments Co., Ltd.), and the YI change rate was calculated from the following formula. The rubber sheet having the standard composition in the calculation formula is a rubber sheet formed from the rubber components used in Examples or Comparative Examples, and is a control rubber sheet that does not contain fine fibrous cellulose (for example, Example). Alternatively, when natural rubber latex is used in the comparative example, the control rubber sheet is a rubber sheet containing the natural rubber of the formulation shown in Table 2). The obtained YI change rate was evaluated in the following four stages A to E.
YI change rate (%) = (Yellowness of rubber sheet-Yellowness of control rubber sheet) / Yellowness of rubber sheet with standard composition x 100
A: YI change rate less than 80% B: YI change rate 80% or more and less than 160% C: YI change rate 160% or more and less than 240% D: YI change rate 240% or more and less than 320% E: YI change rate 320% or more

The rubber sheet (molded body) molded from the rubber composition obtained in the examples had a high tensile strength index. Further, the rubber sheet (molded body) molded from the rubber composition obtained in the examples was excellent in designability and coloration was suppressed. On the other hand, when the substituent removal treatment is not performed or when unmodified coarse fibrous cellulose is used, the tensile strength index and design of the obtained rubber sheet (molded body) are inferior, and coloring is also confirmed. (Comparative Examples 1 to 11).

Claims (8)

A rubber composition containing a rubber component and fibrous cellulose.
The amount of the substituent introduced in the fibrous cellulose is less than 0.5 mmol / g, and the amount is less than 0.5 mmol / g.
A rubber composition having a number average fiber width of 1 to 100 nm of fibrous cellulose contained in the rubber composition. The rubber composition according to claim 1, wherein the rubber composition is a kneaded product containing the rubber component and the fibrous cellulose. The rubber composition according to claim 1 or 2, wherein the substituent is an anionic group. The anionic group is at least one selected from the group consisting of a phosphate group, a substituent derived from a phosphoroxo acid group, a sulfone group, a substituent derived from a sulfone group, a carboxy group and a substituent derived from a carboxy group. The rubber composition according to claim 3. The rubber composition according to claim 3 or 4, wherein the anionic group is a phosphoxoic acid group or a substituent derived from the phosphoxoic acid group. The rubber composition according to any one of claims 1 to 5, wherein the fibrous cellulose has a carbamide group. The rubber component is at least one pre-crosslinking raw material selected from the group consisting of natural rubber, ethylene-propylene-diene copolymer rubber, silicone rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber and butadiene rubber. The rubber composition according to any one of claims 1 to 6. A molded product obtained by molding the rubber composition according to any one of claims 1 to 7.

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