JP2017160583A - Method for producing fiber molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fiber molding capable of easily obtaining a fiber molding of a good alicyclic structure-containing polymer resin by electric field spinning.SOLUTION: There is provided a method for producing a fiber molding of an alicyclic structure-containing polymer resin which includes a step of preparing a polymer solution containing a mixed solvent and an alicyclic structure-containing polymer and a step of performing electric field spinning by using the polymer solution as a spinning material, where the mixed solvent contains a low dielectric constant solvent being an alicyclic hydrocarbon having a relative dielectric constant of less than 25 and a high dielectric constant solvent having a relative dielectric constant of 25 or more, and in the polymer solution, the high dielectric constant solvent is dispersed in a form of particles and has the number average particle size of 40 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a fiber molded body.

  Electrospinning is known as one method for producing a fiber molded body having a shape such as a yarn shape or a nonwoven fabric shape. This is a spinning method in which a voltage is applied between a resin and a flat-shaped collector, the resin is made into a thin fiber state by electric charge, and deposited on the collector. When electrospinning is used, a fiber molded body including resin fibers having a small diameter can be easily formed. In electrospinning, various resins can be used as the spinning material. For example, it is known to use an alicyclic structure-containing polymer resin as a spinning material to obtain a fiber molded body made of the resin. In that case, the alicyclic structure-containing polymer resin can be used in the state of being dissolved in any solvent to form a solution (for example, Patent Documents 1 and 2).

JP 2012-224655 A JP 2010-111978 A

  In electrospinning, normally, a liquid containing a resin is discharged from a fine hole such as a nozzle tip opening, and a voltage is applied in a state where a liquid droplet containing a resin is formed.

  However, when the alicyclic structure-containing polymer resin is dissolved in a solvent suitable for electrospinning to form a polymer solution, the solution stability is insufficient, the solubility is insufficient, There is a problem that the charge required for the implementation cannot be obtained, and it is therefore difficult to easily obtain a good-quality fiber molded body.

  For example, if unwanted particles or bubbles are present in the polymer solution, or if the solution properties are unstable, nozzle clogging, droplet instability at the nozzle tip opening, etc. will result. The droplets formed at the tip opening can be scattered from the nozzle in a non-fibrous shape (such as a droplet shape) instead of a fibrous shape. The polymer solution scattered in such a non-fibrous shape reaches the collector as it is or after a part or all of the solvent contained therein volatilizes, and in the fiber molded body, an undesired granular resin mass. Or a granular hole is formed. Due to the occurrence of such a granular shape, a fiber molded body having a desired shape cannot be obtained, the variation of the fiber diameter of the obtained fiber molded body increases, or the strength of the obtained fiber molded body decreases. , It becomes difficult to peel the fiber molded body from the collector. Further, if the polymer solution is stored for a long time after preparation, such a granular shape is more likely to be generated, and the degree of freedom of the manufacturing process can be reduced.

  Accordingly, an object of the present invention is to provide a method for producing a fiber molded body, in which a high-quality alicyclic structure-containing polymer resin fiber molded body can be easily obtained by electrospinning.

As a result of studying to solve the above problems, the present inventor constituted an incompatible solvent in which a plurality of specific substances were combined as a solvent, and dissolved the alicyclic structure-containing polymer resin into a solution. The inventors have found that the above problems can be solved by performing electrospinning using this, and completed the present invention.
That is, the present invention is as follows.

[1] A method for producing a fiber molded body of an alicyclic structure-containing polymer resin,
A step of preparing a polymer solution containing a mixed solvent and an alicyclic structure-containing polymer, and a step of performing electrospinning using the polymer solution as a spinning material,
The mixed solvent includes a low dielectric constant solvent that is an alicyclic hydrocarbon having a relative dielectric constant of less than 25 and a high dielectric constant solvent having a relative dielectric constant of 25 or more,
In the polymer solution, the high dielectric constant solvent is dispersed in the form of particles, and the number average particle diameter is 40 μm or less.
A method for producing a fiber molded body.
[2] The production method according to [1], wherein the high dielectric constant solvent is an aprotic polar solvent.
[3] The high dielectric constant solvent is selected from the group consisting of N, N-dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, and a mixture thereof. [1] Or the manufacturing method as described in [2].
[4] The production method according to any one of [1] to [3], wherein the low dielectric constant solvent is selected from the group consisting of cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, and a mixture thereof.
[5] The production method according to any one of [1] to [4], wherein the number average particle size of the particles of the high dielectric constant solvent in the polymer solution is 20 μm or less.
[6] The manufacturing method according to any one of [1] to [5], wherein a fiber diameter of the fiber molded body is 0.1 to 5 μm.
[7] The production method according to any one of [1] to [6], wherein the polymer solution further contains an inorganic salt.
[8] The production method according to [7], wherein the concentration of the inorganic salt in the polymer solution is 0.01 mM or more and 10 mM or less.
[9] The production method according to [7] or [8], wherein the inorganic salt is a lithium salt.

  According to the method for producing a fiber molded body of the present invention, a high-quality alicyclic structure-containing polymer resin fiber molded body can be easily obtained by electrospinning. Specifically, a fiber molded body having a small granular shape and a small variation in fiber diameter can be easily manufactured by a method having a high degree of freedom in the manufacturing process.

FIG. 1 is a perspective view schematically showing an example of an electrospinning apparatus and an electrospinning operation using the same, which can be used in the present invention. FIG. 2 is an enlarged side view showing the vicinity of the tip of the nozzle 120 of the apparatus shown in FIG.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and exemplifications, and can be implemented with any modifications without departing from the scope of the claims of the present invention and the equivalents thereof.

  In the present application, what is referred to as a “solution” for convenience of explanation is not limited to one in which all of the components are compatible. That is, the “solution” includes those in which some components are incompatible with other components and exist in the form of particles.

The method for producing a fiber molded body of the present invention comprises:
Step (A): a step of preparing a specific polymer solution, and step (B): a step of performing electrospinning using the polymer solution as a spinning material.

[Process (A)]
The polymer solution prepared in the step (A) includes a specific mixed solvent and an alicyclic structure-containing polymer.

[Mixed solvent]
The mixed solvent includes a low dielectric constant solvent which is an alicyclic hydrocarbon having a relative dielectric constant of less than 25 and a high dielectric constant solvent having a relative dielectric constant of 25 or more.

  The relative dielectric constant of the low dielectric constant solvent can be preferably 10 or less, more preferably 5 or less. The lower limit of the relative dielectric constant of the low dielectric constant solvent is not particularly limited, but may be, for example, 1.5 or more. When a plurality of types of solvents having a relative dielectric constant of less than 25 are included in the mixed solvent, the weighted average thereof can be the relative dielectric constant of the low dielectric constant solvent. In the present application, the weighted average is a weighted average based on the weight ratio.

  The relative dielectric constant of the high dielectric constant solvent is preferably 25 or more, more preferably 30 or more. The upper limit of the relative dielectric constant of the high dielectric constant solvent is not particularly limited, but may be, for example, 50 or less. When a mixed solvent contains a plurality of types of solvents having a relative dielectric constant of 25 or more, the weighted average based on the weight ratio can be used as the relative dielectric constant of the high dielectric constant solvent.

The difference between the relative dielectric constant of the high dielectric constant solvent and the relative dielectric constant of the low dielectric constant solvent in the mixed solvent is preferably larger than a certain level. Specifically, the relative dielectric constant of a high dielectric constant solvent (when multiple types of solvents are included, the weighted average thereof) εr _H and the relative dielectric constant of a low dielectric constant solvent (when multiple types of solvents are included) the value of the difference εr _H -εr _L with their weighted average) .epsilon.r _L is preferably be set to 25 or more, more preferably 30 or more. The upper limit of the value of the difference εr _H −εr _{L from} εr _L is not particularly limited, but may be, for example, 50 or less.

  The low dielectric constant solvent is an alicyclic hydrocarbon. An alicyclic hydrocarbon is a compound having at least one alicyclic structure in the molecule.

  The low dielectric constant solvent is particularly preferably a compound having a relatively high boiling point. Specifically, the boiling point (when a plurality of types of solvents are included, their weighted average) is preferably 130 ° C. or higher, more preferably 150 ° C. or higher. Although the upper limit of a boiling point is not specifically limited, For example, it can be 200 degrees C or less. By having such a high boiling point, scattering of droplets in a non-fibrous shape can be suppressed, and stable formation of a fiber molded body having a desired shape can be easily performed.

  As the low dielectric constant solvent, an alicyclic hydrocarbon that satisfies the above-described requirements for the relative dielectric constant and is liquid in an environment where the production method is carried out can be appropriately selected and used. Examples of low dielectric constant solvents include cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, and mixtures thereof. In particular, decalin is particularly preferable from the viewpoint of having a high boiling point and being able to satisfactorily dissolve the alicyclic structure-containing polymer as a solute.

  As the high dielectric constant solvent, a substance that satisfies the above-described requirements for the relative dielectric constant and becomes liquid in the environment where the production method is carried out can be appropriately selected and used. The high dielectric constant solvent is preferably an aprotic polar solvent from the viewpoint of good electrospinning. Examples of high dielectric constant solvents include N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide (DMSO), and mixtures thereof.

  The ratio of the low dielectric constant solvent to the high dielectric constant solvent in the mixed solvent can be appropriately adjusted so that the dispersion of the high dielectric constant solvent is stabilized, the solubility of the polymer is increased, and good electrospinning can be performed. Specifically, the ratio of the high dielectric constant solvent in 100% by weight of the mixed solvent is preferably 4% by weight or more, more preferably 5% by weight or more, while preferably 15% by weight or less, more preferably 11% by weight. It is as follows. By setting the ratio of the high dielectric constant solvent to 4% by weight or more, it is possible to suppress the scattering of droplets in a non-fibrous shape and easily form a fiber molded body having a desired shape. . By setting the ratio of the high dielectric constant solvent to 15% by weight or less, gelation of the polymer solution can be suppressed to obtain a stable polymer solution, and stable electrospinning can be performed.

(Aricyclic structure-containing polymer)
The alicyclic structure-containing polymer used in the present invention is a polymer having a repeating unit containing an alicyclic structure. The alicyclic structure-containing polymer has good fluidity during molding, and has excellent characteristics such as high heat resistance and low hygroscopicity. Examples of the alicyclic structure in the alicyclic structure-containing polymer include a saturated cyclic hydrocarbon (cycloalkane) structure and an unsaturated cyclic hydrocarbon (cycloalkene) structure, but from the viewpoint of mechanical strength, heat resistance, and the like. Therefore, a cycloalkane structure or a cycloalkene structure is preferable, and among them, a cycloalkane structure is most preferable. The alicyclic structure may be in the main chain or in the side chain, but from the viewpoint of dimensional stability, mechanical strength, heat resistance, etc., those containing an alicyclic structure in the main chain are preferred. . The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15 in the mechanical strength, The properties of heat resistance and moldability of the resulting product are highly balanced.

  The ratio of the repeating unit containing the alicyclic structure in the alicyclic structure-containing polymer can be a ratio suitable for the purpose of use. The proportion is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the ratio of the repeating unit containing the alicyclic structure in the alicyclic structure-containing polymer is within this range, it is preferable from the viewpoint of the heat resistance of the obtained molded body.

  Specific examples of the alicyclic structure-containing polymer include (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, and (4) a vinyl alicyclic polymer. Examples thereof include hydrocarbon polymers and hydrides of (1) to (4). Among these, from the viewpoints of heat resistance, mechanical strength, and the like, norbornene polymer hydrides, vinyl alicyclic hydrocarbon polymers, and hydrides thereof are preferable.

(1) Norbornene-based polymers Norbornene-based polymers are roughly classified into those obtained by ring-opening polymerization and those obtained by addition polymerization.
Examples of those obtained by ring-opening polymerization include ring-opening polymers of norbornene monomers, ring-opening polymers of norbornene monomers and monomers capable of ring-opening copolymerization thereof, hydrides thereof, and the like. Examples of those obtained by addition polymerization include addition polymers of norbornene monomers and addition polymers of norbornene monomers and monomers copolymerizable therewith. Among these, a ring-opening polymer hydride of a norbornene-based monomer is preferable from the viewpoint of heat resistance, mechanical strength, and the like.

Examples of norbornene-based monomers include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and its derivatives (having substituents in the ring), tricyclo [4.3.0 ^1,6 . 1 ^2,5 ] deca-3,7-diene (common name dicyclopentadiene) and derivatives thereof, 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name) Methanotetrahydrofluorene: 1,4-methano-1,4,4a, 9a-tetrahydrofluorene) and its derivatives, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene) and its derivatives.

Examples of the substituent include an alkyl group, an alkylene group, a vinyl group, an alkoxycarbonyl group, and an alkylidene group. The norbornene-based monomer may have one or more of these. Specifically, as a specific example of the norbornene-based monomer having a substituent, 8-methoxycarbonyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-methyl-8-methoxycarbonyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethylidene-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene and the like.
These norbornene monomers are used alone or in combination of two or more.

A ring-opening polymer of a norbornene-based monomer or a ring-opening polymer of a norbornene-based monomer and a monomer capable of ring-opening copolymerization thereof is obtained by polymerizing a monomer component in the presence of a known ring-opening polymerization catalyst. Can do. Examples of the ring-opening polymerization catalyst include a catalyst comprising a metal halide such as ruthenium or osmium and a nitrate or acetylacetone compound and a reducing agent, or a metal halide such as titanium, zirconium, tungsten or molybdenum or acetylacetone. The catalyst which consists of a compound and an organoaluminum compound is mentioned.
Examples of the monomer capable of ring-opening copolymerization with a norbornene monomer include monocyclic olefin monomers such as cyclohexene, cycloheptene, and cyclooctene.
The ring-opening polymer hydride of a norbornene-based monomer is usually prepared by adding a known hydrogenation catalyst containing a transition metal such as nickel or palladium to the polymerization solution of the above-mentioned ring-opening polymer so that the carbon-carbon unsaturated bond is hydrogenated. Can be obtained.

  Addition polymers of norbornene monomers, or addition polymers of norbornene monomers and monomers copolymerizable therewith, use these monomers as well known addition polymerization catalysts such as titanium, zirconium or vanadium compounds and organoaluminum compounds. It can obtain by polymerizing using the catalyst which consists of these.

Examples of monomers that can be addition-copolymerized with norbornene-based monomers include ethylene, propylene, 1-butene, 1-pentene, 1-hexene and other α-olefins having 2 to 20 carbon atoms, and derivatives thereof; cyclobutene, cyclopentene , Cyclohexene, cyclooctene, cycloolefins such as 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, and derivatives thereof; 1,4-hexadiene, 4-methyl-1,4-hexadiene , Non-conjugated dienes such as 5-methyl-1,4-hexadiene and 1,7-octadiene; Among these, α-olefins are preferable and ethylene is particularly preferable.
These monomers capable of addition copolymerization with norbornene-based monomers can be used alone or in combination of two or more. In the case of addition copolymerization of a norbornene monomer and an addition copolymerizable monomer, the ratio of the structural unit derived from the norbornene monomer and the structural unit derived from the addition copolymerizable monomer in the addition polymer is the weight. The ratio is appropriately selected so as to be in the range of usually 30:70 to 99: 1, preferably 50:50 to 97: 3, more preferably 70:30 to 95: 5.

(2) Monocyclic Cyclic Olefin Polymer Examples of monocyclic cycloolefin polymers include addition polymers of monocyclic cycloolefin monomers such as cyclohexene, cycloheptene, and cyclooctene.

(3) Cyclic conjugated diene polymer As examples of the cyclic conjugated diene polymer, polymers obtained by subjecting a cyclic conjugated diene monomer such as cyclopentadiene and cyclohexadiene to 1,2- or 1,4-addition polymerization, and The hydride etc. are mentioned.

(4) Vinyl alicyclic hydrocarbon polymer Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon monomers and their hydrides; vinyl alicyclic hydrocarbon polymers. A copolymer of a monomer and a copolymerizable monomer and a hydride thereof; a hydride of an aromatic ring portion of a polymer of a vinyl aromatic monomer; and a weight of a vinyl aromatic monomer. Examples thereof include a hydride of an aromatic ring portion of a copolymer and a copolymer of the copolymer and a monomer copolymerizable therewith. Examples of vinyl alicyclic hydrocarbon monomers include vinylcyclohexene and vinylcyclohexane. Examples of vinyl aromatic monomers include styrene and α-methylstyrene. Examples of the copolymer include a random copolymer and a block copolymer. Examples of block copolymers include diblock, triblock, or higher multiblock and gradient block copolymers.

  In the step (A), as the alicyclic structure-containing polymer, a commercially available resin containing the alicyclic structure-containing polymer can be used. Examples of such commercially available resins include trade name “ZEONOR” (manufactured by ZEON CORPORATION), trade name “ZEONEX” (manufactured by ZEON CORPORATION), trade name “ARTON” (manufactured by JSR Corporation), trade name “ “Apel” (manufactured by Mitsui Chemicals) and trade name “TOPAS” (manufactured by TOPAS ADVANCED POLYMERS).

[Inorganic salt]
In addition to the mixed solvent and the alicyclic structure-containing polymer, the polymer solution preferably further contains an inorganic salt, and particularly preferably contains a lithium salt. When the polymer solution contains an inorganic salt, the dielectric constant of the polymer solution can be increased.
Examples of inorganic salts that can be contained in the polymer solution include inorganic alkali metal salts (eg, LiBr, LiCl, NaNO ₃ , NaCl) and inorganic alkaline earth metal salts (eg, CaCl ₂ ), among which LiBr, LiCl, etc. The lithium salt is preferable, and LiCl (lithium chloride) is particularly preferable.
The concentration of the inorganic salt in the polymer solution is not particularly limited, but is usually 0.01 mM or more, preferably 0.05 mM or more, more preferably 0.1 mM or more, and usually 10 mM or less, preferably Is 5 mM or less, more preferably 1 mM or less. The dielectric constant of a polymer solution can be effectively raised because the density | concentration of an inorganic salt is more than the said lower limit. Moreover, it can suppress that inorganic salt precipitates without melt | dissolving in a polymer solution because the density | concentration of inorganic salt is below the said upper limit.

[Optional ingredients]
The polymer solution can contain an optional component in addition to the mixed solvent and the alicyclic structure-containing polymer. For example, when an alicyclic structure-containing polymer resin containing an alicyclic structure-containing polymer and an optional component is used as a material for preparing a polymer solution, any component in the resin is It may be contained as it is in the combined solution. Examples of optional components include antioxidants, heat stabilizers, light stabilizers, weathering stabilizers, UV absorbers, near infrared absorbers, and other stabilizers; resin modifiers such as lubricants; dyes and pigments, etc. Coloring agents; antistatic agents and the like. These amounts can be appropriately adjusted within a range not impairing the object of the present invention. However, from the viewpoint of producing a fiber molded body of a high-quality alicyclic structure-containing polymer resin, it is preferable that the ratio of any component is small. Specifically, the ratio of the alicyclic structure-containing polymer to the total solid content (total of components other than the solvent) in the polymer solution is preferably 90% by weight or more, more preferably 95% by weight or more, and even more. Preferably it is 99 weight% or more.

  The ratio of the total solid content in the polymer solution can be appropriately adjusted within a range suitable for electrospinning. For example, the proportion of total solids is preferably 15% by weight or more, more preferably 20% by weight or more, while preferably 35% by weight or less, more preferably 30% by weight or less.

[Properties of polymer solution]
In the polymer solution, the high dielectric constant solvent is dispersed in the form of particles, and the number average particle diameter is 40 μm or less. The number average particle size of the particles of the high dielectric constant solvent can be preferably 20 μm or less, more preferably 15 μm or less. On the other hand, at least a part of the high dielectric constant solvent needs to be present in the form of particles rather than being dissolved in other components, and the lower limit of the number average particle diameter of the particles is 0.5 μm. This can be done. When the number average particle diameter of the particles of the high dielectric constant solvent is in this range, scattering of the droplets in the non-fibrous shape in the electrospinning process is suppressed, and the fiber molded body having a desired shape is stably formed. Formation can be performed easily. In addition, problems such as clogging of the polymer solution in the nozzle can be suppressed, and as a result, electrospinning with little variation in fiber diameter can be easily achieved. Furthermore, the pot life of the polymer solution can be extended. As a result, the degree of freedom in the production process is increased, and the production method can be more easily performed. The number average particle size of the high dielectric constant solvent can be adjusted by changing the stirring conditions of the polymer solution. The number average particle size of the high dielectric constant solvent is determined by dropping a polymer solution onto a glass slide at room temperature, using a digital microscope (eg, trade name “VHX-5000”, manufactured by Keyence), an inverted phase contrast microscope (eg, trade name) It can obtain | require by observing 300 times using "CKX41", the product made from Olympus, and measuring those particle sizes.

  Since the high dielectric constant solvent is thus dispersed in the polymer solution, a high-quality alicyclic structure-containing polymer resin fiber molded body can be easily obtained by electrospinning. Although not bound by a specific theory, the following may be considered as the reason. That is, when the alicyclic structure-containing polymer resin is dissolved in a solvent consisting only of a low dielectric constant solvent, the solution is insufficiently charged, and it becomes difficult to form a good-quality fiber molded body. On the other hand, when the alicyclic structure-containing polymer resin is dissolved in a solvent composed only of a high dielectric constant solvent, and the alicyclic structure-containing polymer resin is a mixed solvent in which a high dielectric constant solvent and a low dielectric constant solvent are compatible. When dissolved in the alicyclic structure-containing polymer, the solubility of the alicyclic structure-containing polymer is insufficient or the stability of the dissolved state is lowered, and it is difficult to easily form a good-quality fiber molded body. . Here, the present inventors have found that a mixed solvent of a specific low dielectric constant solvent and a high dielectric constant solvent is used as the solvent, and the high dielectric constant solvent is dispersed in the specific state described above. Can achieve both good solution charge, polymer solution stability, and high alicyclic structure-containing polymer solubility, resulting in good quality alicyclic structure by electrospinning. A fiber molded body of the containing polymer resin can be easily obtained.

  The viscosity of the polymer solution can be appropriately adjusted within a range suitable for electrospinning. The viscosity is preferably 0.5 Pa · s or more, more preferably 3 Pa · s or more, and preferably 11 Pa · s or less, more preferably 10 Pa · s or less. As the viscosity of the polymer solution, a value measured at 23 ° C. with a vibration viscometer can be adopted. By setting the viscosity to be equal to or higher than the lower limit of the above range, scattering of droplets in a non-fibrous shape can be suppressed, and a stable formation of a fiber molded body having a desired shape can be easily performed. Further, by setting the viscosity to be equal to or lower than the upper limit of the above range, it is possible to suppress the fiber diameter from becoming excessive and to smoothly discharge the polymer solution. The viscosity of the polymer solution can be adjusted, for example, by adjusting the ratio of the solid content.

(Preparation of polymer solution)
The procedure for preparing the polymer solution in the step (A) is not particularly limited and may be any procedure. Specifically, it can be performed by mixing and dispersing the components of the polymer solution in an arbitrary order. Examples of specific mixing and dispersion procedures include: (i) a method of dissolving an alicyclic structure-containing polymer in a low dielectric constant solvent to form a mixture, and further dispersing the high dielectric constant solvent in the mixture; and (ii) A method of mixing a low dielectric constant solvent and a high dielectric constant solvent to obtain a mixed solvent, and further dissolving the alicyclic structure-containing polymer in the mixed solvent. Among these, (i) is preferable because the polymer solution can be easily dissolved and the particle diameter of the high dielectric constant solvent can be easily controlled.
When the polymer solution contains an inorganic salt, the method for preparing the polymer solution containing the inorganic salt is not particularly limited. For example, in the mixing and dispersing procedure, a low dielectric constant solvent to which the inorganic salt is added is used. Method, method using a high dielectric constant solvent to which an inorganic salt is added, method using a mixed solvent of a low dielectric constant solvent and a high dielectric constant solvent, to which an inorganic salt is added, a low dielectric constant solvent, a high dielectric constant solvent, and an alicyclic ring The method of preparing the solution containing a formula structure containing polymer and adding an inorganic salt to this solution is mentioned.

When mixing or dispersing the components of the polymer solution, for example, mixing or dispersion by ultrasonic waves and / or stirring using a stirrer can be performed.
As an apparatus for performing mixing or dispersion by ultrasonic waves, for example, an ultrasonic cleaning machine (for example, trade name “Branson CPX2800”, supplied from Nippon Emerson Corporation) can be used.
As the stirrer, an apparatus capable of performing stirring in which bubbles are not mixed into the viscous solution and the dispersion of the high dielectric constant solvent is sufficiently achieved is preferable. Specifically, a planetary mixer (for example, trade name “ARE-250”, manufactured by Sinky Co., Ltd.) and a vortex mixer can be used.

  The alicyclic structure-containing polymer may be dissolved in the low dielectric constant solvent by heating the solvent. However, by appropriately selecting a low dielectric constant solvent that can easily dissolve the alicyclic structure-containing polymer (decalin, ethylcyclohexane, methylcyclohexane, cyclohexane, etc.) A dissolution operation can be easily performed at room temperature (10 to 30 ° C.), and a stable solution having a high polymer concentration can be obtained.

[Process (B)]
In the step (B), electrospinning is performed using the polymer solution obtained in the step (A) as a spinning material.
Electrospinning is a spinning method in which a voltage is applied between a resin and a plate-like collector, the resin is made into a thin fiber state by electric charge, and deposited on the collector. In electrospinning, normally, a liquid containing a resin is discharged from a fine hole such as a nozzle tip opening, and a voltage is applied in a state where a liquid droplet containing a resin is formed. In this case, by applying a voltage, the droplets are deformed into a conical shape called a Taylor cone, and the resin is ejected in the form of fine fibers toward the collector, thereby achieving spinning.

  FIG. 1 is a perspective view schematically showing an example of an electrospinning apparatus and an electrospinning operation using the electrospinning apparatus that can be used in the present invention, and FIG. 2 shows the vicinity of the tip of a nozzle 120 of the apparatus shown in FIG. It is a side view which expands and shows. In FIG. 1, the electrospinning apparatus 10 includes an extrusion apparatus 100 and a collector 130, and the extrusion apparatus 100 includes a container 110 and a nozzle 120 that can extrude contents. In this example, the container 110 has a syringe shape including a plunger 111 and a barrel 112. The collector 130 has a flat plate shape. The collector 130 is provided in a direction in which the front surface 130 </ b> U faces the nozzle 120. The apparatus 10 further includes an energization device 140 that applies a voltage to the nozzle 120 and the collector 130. In this example, the energization device 140 has a positive electrode electrically connected to the nozzle 120 and a negative electrode electrically connected to the collector 130.

  In the operation of the apparatus 10, the polymer solution is filled in the barrel 112, the plunger 111 is operated, and the polymer solution is gradually discharged from the tip opening 121 of the nozzle 120. Thereby, a droplet 151 of the polymer solution is formed in the tip opening 121 of the nozzle 120. In this state, when a voltage is applied to the nozzle 120 and the collector 130 by the energizing device 140, the droplet of the polymer solution is transformed into a conical shape (Taylor cone) as shown in FIG. A fine fibrous polymer solution 152 is ejected. From the ejected polymer solution, a part or all of the solvent is volatilized, and fibers mainly composed of the solid content of the polymer solution are deposited on the collector in the form of a nonwoven fabric, whereby spinning can be achieved.

  In the production method of the present invention, by using the specific polymer solution prepared in the step (A) as the polymer solution, a high-quality alicyclic structure-containing polymer resin fiber molded body can be easily obtained in the step (B). Can do. In particular, in the production method of the present invention, scattering of the polymer solution in the non-fibrous shape in the step (B) can be suppressed, and as a result, the generation of an undesirable granular shape can be suppressed. For example, when unwanted particles or bubbles are present in the polymer solution, or the solution properties are unstable, the nozzle 120 is clogged, the droplet 151 at the nozzle tip opening 121 becomes unstable, etc. As a result, the droplet 151 formed in the nozzle tip opening 121 can be scattered from the nozzle in a non-fibrous shape (droplet shape, etc.), for example, in the direction of the arrow A1. The polymer solution scattered in such a non-fibrous shape reaches the collector as it is or after a part or all of the solvent contained therein volatilizes, and in the fiber molded body, an undesired granular resin mass. Or a granular hole is formed. Due to the occurrence of such a granular shape, a fiber molded body having a desired shape cannot be obtained, the variation of the fiber diameter of the obtained fiber molded body increases, or the strength of the obtained fiber molded body decreases. , It becomes difficult to peel the fiber molded body from the collector. Here, in the production method of the present invention, by using the specific polymer solution prepared in the step (A) as the polymer solution, in the step (B), such a polymer solution is scattered in a non-fibrous shape. As a result, these problems can be suppressed.

  A commercially available apparatus can be used as the electrospinning apparatus for the step (B). For example, the product name “NANON” (manufactured by MEC Co., Ltd.) can be used.

  The voltage applied to the nozzle and collector in the step (B) is preferably 10 kV or more, more preferably 20 kV or more, and preferably 30 kV or less, more preferably 27 kV or less. By setting the applied voltage within this range, spinning from the nozzle can be stabilized, and the scattering of droplets in a non-fibrous shape and the formation of intermittent fibers can be suppressed.

  In the step (B), the distance between the electrodes, that is, the distance from the nozzle tip to the collector is preferably 5 mm or more, more preferably 100 mm or more, and preferably 300 mm or less, more preferably 200 mm or less. By setting the distance between the electrodes within this range, stable spinning can be achieved.

  In the step (B), the discharge speed of the polymer solution from the nozzle is preferably 0.01 mL / hr or more, more preferably 0.1 mL / hr or more, while preferably 3 mL / hr or less, more preferably 1 .5 mL / hr or less. By setting the discharge speed within this range, it is possible to suppress the scattering of the droplets in a non-fibrous shape, and it is possible to stabilize the droplets of the polymer solution at the nozzle tip during spinning. Spinning can be achieved.

  In the step (B), the relative humidity of the environment for spinning is preferably 20% or more, and preferably 40% or less. By setting the relative humidity within this range, the solvent can be volatilized stably, and stable spinning can be achieved. In carrying out the step (B), it is often necessary to perform dehumidification in order to obtain such relative humidity. In the dehumidifying process, air is often heated, and therefore the temperature of the environment in which spinning is performed in the process (B) can be a normal room temperature or higher, for example, in the range of 20 ° C to 35 ° C. Therefore, by employing a solvent that can be stably volatilized in such a temperature range as the low dielectric constant solvent, stable spinning can be advantageously achieved. From such a viewpoint, as the low dielectric constant solvent, among those exemplified above, decalin, ethylcyclohexane and the like are particularly preferable.

[Optional process]
The production method of the present invention may include an optional step in addition to the step (A) and the step (B). For example, a structure containing an alicyclic structure-containing polymer deposited on the collector after the step (B) may be used as a fiber molded body as a product as it is. It is good also as a fiber molding. For example, a process of heating the structure and removing the solvent remaining in the structure can be performed.

(Fiber molded product)
The fiber molded body obtained by the production method of the present invention becomes a molded body of an alicyclic structure-containing polymer resin. Specifically, it can be a molded body substantially composed of an alicyclic structure-containing polymer and other solid content contained in the polymer solution.

  The shape of the fiber molded body may be any shape including a fibrous shape or a fibrous shape. For example, the shape may be a nonwoven fabric shape, a thread shape, or a string shape. The production method of the present invention can particularly easily produce a nonwoven fabric as a fiber molded body.

  Although the diameter of the fiber contained in a fiber molded object can be suitably adjusted according to a desired use, it can be set as the fiber which has a diameter of the range of 0.1-5 micrometers, for example. The diameter of the fiber can be adjusted by appropriately adjusting conditions such as the viscosity of the polymer solution and the discharge speed of the polymer solution.

[Modification]
The manufacturing method of the present invention is not limited to the example specifically described above, and may be variously modified.
For example, in the example shown in FIG. 1 and FIG. 2, the container 110 that pushes the polymer solution to the nozzle in the extrusion apparatus has a syringe shape, but the present invention is not limited to this, and instead of the container 110, For example, any device such as a pump capable of feeding the polymer solution to the nozzle can be used.
Further, for example, in the example shown in FIGS. 1 and 2, the collector 130 has a flat plate shape. However, the present invention is not limited to this, and the collector shape may be a fiber molded body having a desired shape. It can be any shape suitable for obtaining. For example, a long nonwoven fabric can be continuously produced by forming the collector into a drum shape, a belt shape, or the like, and performing electrospinning on the peripheral surface while rotating the collector.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.
In the following description, “%” and “part” representing amounts are based on weight unless otherwise specified. Moreover, the following operation was performed in normal temperature normal pressure atmosphere unless otherwise indicated.

〔Evaluation method〕
(Measurement of viscosity)
The viscosity of the polymer solution was measured at 23 ° C. with a tuning fork type vibration viscometer (“SV-10”, manufactured by A & D) in accordance with JIS Z8803: 2011.

(Measurement of particle size of high dielectric constant solvent)
The particle diameter of the high dielectric constant solvent was measured by the following method (a) or (b).
(A) The polymer solution was dropped onto a slide glass at room temperature and observed at 300 times using a digital microscope (trade name “VHX-5000”, manufactured by Keyence). The particles of 60 high dielectric constant solvents were arbitrarily selected, their particle sizes were measured, and the average value was obtained as the number average particle size of the high dielectric constant solvent.
(B) The polymer solution was dropped onto a slide glass at room temperature and observed at 300 times using an inverted phase contrast microscope (trade name “CKX41”, manufactured by Olympus). Arbitrarily 2800 or more particles of a high dielectric constant solvent were selected, their particle size was measured by image analysis, and the average value was determined as the number average particle size of the high dielectric constant solvent.

(Measurement of fiber diameter)
The fibers in the nonwoven fabric were observed by FE-SEM, the fiber diameters at 20 arbitrary positions were measured, and the average value, standard deviation (σ), and coefficient of variation (= σ / average value) were determined. As the FE-SEM apparatus, model number “7401F” (manufactured by JEOL Ltd.) was used, and the observation conditions were an acceleration voltage of 5 kV, an emission current of 10 μA, a working distance of 8 mm, and an observation magnification of 4500 times.

(Evaluation of presence or absence of granular shape)
The surface of the nonwoven fabric was observed at a magnification of 100 using a digital microscope (trade name “VHX-5000”, manufactured by Keyence), and the presence or absence of a granular shape having a diameter of 40 μm to 500 μm was examined. When a granular shape was seen, the granular shape was “present”, and when it was not seen, it was “no”. Further, when the granular shape could be visually observed, it was visually confirmed and evaluated as “present”.

[Example 1]
(1-1. Process (A))
As a resin containing an alicyclic structure-containing polymer, a pellet having a trade name “ZEONOR1430” (manufactured by Nippon Zeon Co., Ltd.) was prepared. 11 g of this pellet was dissolved in 27.55 g of decalin (manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a mixture. Dissolution is performed by putting a stir bar in the mixture and stirring using a magnetic stirrer (hot stirrer REXIM, model number RSH-1DN manufactured by ASONE) until it is confirmed that the mixture has become a viscous, transparent and uniform solution. went.

  Thereafter, 1.45 g of DMF (manufactured by Wako Pure Chemical Industries, Ltd.) is further added to the mixture, and the mixture is stirred for 2 minutes at 2000 rpm with a planetary mixer (trade name “ARE-250”, manufactured by Shinky Corporation). DMF was uniformly dispersed in the mixture. Thereby, a polymer solution containing decalin, DMF, and an alicyclic structure-containing polymer resin was obtained. Using the obtained polymer solution as a sample, the viscosity was measured and the particle diameter of the high dielectric constant solvent was measured. The particle diameter of the high dielectric constant solvent was measured by the above method (a).

(1-2. Process (B))
Immediately after obtaining the polymer solution in (1-1), electrospinning was performed using this as a spinning material. Electrospinning was performed using an electrospinning apparatus (trade name “NANON”, manufactured by MEC Co., Ltd.) schematically shown in FIGS. 1 and 2. More specifically, a 5 mL syringe-like container 110 is filled with about 2.5 mL of the polymer solution, and a 27 G (inner diameter 0.2 mm) metal nozzle 120 is attached to the tip of the container 110 to form a flat plate shape. It was installed to face the collector 130. An aluminum foil was laid on the surface of the collector 130 and the following spinning conditions were set. Then, a voltage was applied between the nozzle 120 and the collector 130 to perform electrospinning.

Electrospinning conditions: Applied voltage 22 kV, polymer solution discharge speed 0.5 mL / hr, distance from nozzle tip to collector (distance between electrodes) 150 mm, spinning time 2 hours, nozzle 27G (inner diameter 0.2 mm), nozzle Length 15mm, device temperature 30 ° C, device relative humidity 30%.

  As a result, the polymer solution can be ejected from the nozzle into a filamentous shape without causing the droplets to scatter in a non-fibrous shape, and the spinning can be performed stably. The nonwoven fabric-like fiber molded body was formed.

(1-3. Evaluation of fiber molded body)
About the nonwoven fabric obtained by (1-2), the fiber diameter was measured and the average value, the standard deviation, and the variation coefficient were calculated | required.

(1-4. Evaluation of presence or absence of granular shape)
About the nonwoven fabric obtained by (1-2), the presence or absence of the granular shape was evaluated.

(1-5. Pot life evaluation)
After obtaining the polymer solution in (1-1) and after 2 weeks, the nonwoven fabric was obtained in the same manner as in the above (1-2) and (1-4) except that the polymer solution was used. The presence or absence was evaluated.

[Example 2]
In (1-1), a polymer solution and a nonwoven fabric were obtained and evaluated in the same manner as in Example 1 except that DMSO was used instead of DMF.

Example 3
A nonwoven fabric was obtained and evaluated in the same manner as in Example 1 except that the following points were changed.
In (1-1), the amount of the resin pellet containing the alicyclic structure-containing polymer was changed from 11 g to 10 g.
In (1-1), 28.5 g of a mixture of decalin and ethylcyclohexane (both manufactured by Wako Pure Chemical Industries, Ltd.) in a weight ratio of 80:20 was used instead of 27.55 g of decalin.
In (1-1), the amount of DMF was changed from 1.45 g to 1.5 g.

Example 4
In the step of (1-1), in the stirring after the addition of DMF, the polymer solution and the nonwoven fabric were prepared in the same manner as in Example 1 except that the condition was changed from 2 minutes at 2000 rpm to 2 minutes at 500 rpm. Obtained and evaluated.

Example 5
In (1-1), as the resin pellet containing the alicyclic structure-containing polymer, the pellet 11g of the trade name “ARTON F5023” (manufactured by JSR Corporation) is used instead of the pellet 11g of the trade name “ZEONOR1430”. The polymer solution and the nonwoven fabric were obtained and evaluated in the same manner as in Example 1.

Example 6
A nonwoven fabric was obtained and evaluated in the same manner as in Example 1 except that the following points were changed.
-In (1-1), as resin pellets containing an alicyclic structure-containing polymer, instead of pellets 11g with the trade name "ZEONOR 1430", pellets 11g with the trade name "ARTON F5023" (manufactured by JSR Corporation) Using.
In (1-1), the amount of decalin was changed from 27.55 g to 26.1 g.
In (1-1), the amount of DMF was changed from 1.45 g to 2.9 g.

Example 7
A trade name “ZEONEX 790R” (manufactured by Nippon Zeon Co., Ltd.) was prepared as a resin pellet containing an alicyclic structure-containing polymer. 10.0 g of this pellet was dissolved in 36.0 g of a mixed solvent of decalin and DMF at a weight ratio of 90:10 containing lithium chloride at a concentration of 1 mM to obtain a mixture. Dissolution was continued by inverting the mixture until it was confirmed that the mixture was a viscous and homogeneous solution.
Thereafter, the mixture was dispersed by vigorously stirring with a vortex mixer for 1 minute, and then irradiated with ultrasonic waves at 110 W for 2 minutes with an ultrasonic cleaner (trade name “Branson CPX2800”, supplied by Nippon Emerson Co., Ltd.) A polymer solution containing decalin, DMF, lithium salt, and an alicyclic structure-containing polymer was obtained. The polymer solution after the pellets are dissolved in the mixed solvent is almost the same as the volume of the mixed solvent. Therefore, the concentration of lithium chloride in the mixed solvent may be regarded as the concentration of lithium chloride in the polymer solution. The obtained polymer solution was used as a sample, and the particle size of the high dielectric constant solvent was measured by the method (b).
Using the obtained polymer solution, the applied voltage, the discharge speed of the polymer solution, and the distance between the electrodes in the electrospinning conditions were changed as described below (1-2. Step ( Electrospinning was performed in the same manner as in B)).
Applied voltage 28 kV, polymer solution discharge speed 1.0 mL / hr, distance between electrodes 100 mm
The non-woven fiber shaped product obtained by electrospinning was evaluated in the same manner as in Example 1.

Example 8
Electrospinning was performed in the same manner as in Example 7 except that the weight ratio of decalin and DMF in the mixed solvent was changed to 95: 5, and the resulting nonwoven fabric-like fiber molded body was evaluated in the same manner as in Example 1. .

[Comparative Example 1]
In (1-1), a polymer solution was obtained and evaluated in the same manner as in Example 1 except that DMF was not added and the amount of decalin was changed to 29.00 g. In addition, an attempt was made to form a non-woven fabric, but no fibers were generated, and a granular resin was deposited on the collector, and electrospinning could not be performed.

[Comparative Example 2]
In the step (1-1), in the stirring after the addition of DMF, the polymer solution and the non-woven fabric were prepared in the same manner as in Example 1 except that the conditions were changed from 2 minutes at 2000 rpm to 2 minutes at 100 rpm. Obtained and evaluated. In the obtained non-woven fabric, a granular shape was observed.

[Comparative Example 3]
(C3-1. Step (A))
As a resin pellet containing an alicyclic structure-containing polymer, a pellet having a trade name “ARTON F5023” (manufactured by JSR Corporation) was prepared. 12 g of this pellet was dissolved in 28 g of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a mixture, which was used as a polymer solution. Dissolution is performed by putting a stir bar in the mixture and stirring using a magnetic stirrer (hot stirrer REXIM, model number RSH-1DN manufactured by ASONE) until it is confirmed that the mixture has become a viscous, transparent and uniform solution. went. The obtained polymer solution was used as a sample, and the viscosity was measured.

(C3-2. Step (B) and Evaluation)
In the same manner as in (1-2) to (1-5) of Example 1, except that the polymer solution obtained in (C3-1) was used instead of the polymer solution obtained in (1-1). The nonwoven fabric was obtained and evaluated.
In electrospinning, solidification of the polymer solution was observed at the nozzle tip. Since spinning became difficult, spinning was performed while cleaning the tip of the nozzle as appropriate. In the obtained non-woven fabric, a granular shape was observed.

[Comparative Example 4]
(C4-1. Step (A))
As a resin containing an alicyclic structure-containing polymer, a pellet having a trade name “ARTON F5023” (manufactured by JSR Corporation) was prepared. 12 g of this pellet was dissolved in 25.2 g of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a mixture. Dissolution is performed by putting a stir bar in the mixture and stirring using a magnetic stirrer (hot stirrer REXIM, model number RSH-1DN manufactured by ASONE) until it is confirmed that the mixture has become a viscous, transparent and uniform solution. went.

  Thereafter, 2.8 g of DMF (manufactured by Wako Pure Chemical Industries, Ltd.) was further added to the mixture and stirred. As a result, DMF was compatible with toluene and the like to obtain a polymer solution that was a uniform solution. The obtained polymer solution was used as a sample, and the viscosity was measured. Further, no attempt was made to measure the particle size of the high dielectric constant solvent, and no particles were observed.

(C4-2. Step (B) and evaluation)
Instead of the polymer solution obtained in (1-1), the same procedure as in (1-2) to (1-5) of Example 1 was used except that the polymer solution obtained in (C4-1) was used. The nonwoven fabric was obtained and evaluated.
In electrospinning, solidification of the polymer solution was observed at the nozzle tip. Since spinning became difficult, spinning was performed while cleaning the tip of the nozzle as appropriate. In the obtained non-woven fabric, a granular shape was observed.

[Comparative Example 5]
In the step (1-1), in the stirring after the addition of DMF, the polymer solution and the non-woven fabric were prepared in the same manner as in Example 5 except that the conditions were changed from 2 minutes at 2000 rpm to 2 minutes at 100 rpm. Obtained and evaluated. In the obtained non-woven fabric, a granular shape was observed.

  The results of Examples and Comparative Examples are summarized in Tables 1 to 3.

  As is apparent from the results in Table 1, in Examples 1 to 6, good electrospinning was performed, and a fiber molded body having no granular shape and little variation in fiber diameter could be produced.

  In addition, as is clear from the results in Table 2, also in Examples 7 and 8 using a polymer solution containing a lithium salt as an inorganic salt, good electrospinning was performed, and the production of a fiber molded product with little variation in fiber diameter was made. Was able to do.

DESCRIPTION OF SYMBOLS 10: Electrospinning apparatus 100: Extrusion apparatus 110: Container 111: Plunger 112: Barrel 120: Nozzle 121: Nozzle tip opening 130: Collector 130U: Collector front surface 140: Current supply apparatus 151: Liquid of polymer solution Drop 152: Fibrous polymer solution

Claims (9)

A method for producing a fiber molded body of an alicyclic structure-containing polymer resin,
A step of preparing a polymer solution containing a mixed solvent and an alicyclic structure-containing polymer, and a step of performing electrospinning using the polymer solution as a spinning material,
The mixed solvent includes a low dielectric constant solvent that is an alicyclic hydrocarbon having a relative dielectric constant of less than 25 and a high dielectric constant solvent having a relative dielectric constant of 25 or more,
In the polymer solution, the high dielectric constant solvent is dispersed in the form of particles, and the number average particle diameter is 40 μm or less.
A method for producing a fiber molded body.   The production method according to claim 1, wherein the high dielectric constant solvent is an aprotic polar solvent.   3. The high dielectric constant solvent according to claim 1 or 2, wherein the high dielectric constant solvent is selected from the group consisting of N, N-dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, and mixtures thereof. The manufacturing method as described.   The manufacturing method according to any one of claims 1 to 3, wherein the low dielectric constant solvent is selected from the group consisting of cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, and a mixture thereof.   The manufacturing method of any one of Claims 1-4 whose number average particle diameter of the particle | grains of the said high dielectric constant solvent in the said polymer solution is 20 micrometers or less.   The manufacturing method of any one of Claims 1-5 whose fiber diameter of the said fiber molded object is 0.1-5 micrometers.   The manufacturing method according to claim 1, wherein the polymer solution further contains an inorganic salt.   The manufacturing method of Claim 7 whose density | concentration in the said polymer solution of the said inorganic salt is 0.01 mM or more and 10 mM or less.   The production method according to claim 7 or 8, wherein the inorganic salt is a lithium salt.

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