JP2002293602A - Papermaking process of hydraulic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic material papermaking process which is used for the production of a papermaking-formed sheet of a hydraulic material by a cylinder machine method while using Vinylon (R) fiber (polyvinyl alcohol-based fiber) as a reinforcing material, and also is a rational production process of such a formed sheet, using a composition that realizes substitution of a large amount of cement by fly ash, from the view point of carbon dioxide emission control. SOLUTION: This process involves: preparing a solid material comprising, on the basis of the total solid content, 15-40 wt.% of fly ash, 1-10 wt.% of fumed silica, 1-3 wt.% of reinforcing Vinylon (R) fiber having 1.5-5.0 dtex fineness, 4-10 mm fiber length, >=10 cN/dtex strength and 4-10% elongation, 1-5 wt.% of pulp having CSF (drainability specified in JIS P 8121) of 70-130, and the remainder of cement; and subjecting a slurry of the solid material to papermaking to form a hydraulic material formed sheet; wherein further preferably, the solid material also contains 0.3-2.0 wt.% sepiolite, in order to improve ply adhesion of the formed sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article of a hydraulic material formed by a round net method or a Hatschek method and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a molded article formed by molding a hydraulic material by a papermaking method has been widely used as a roof tile, a sizing material, and the like. Such a molded article is a hydraulic material,
It is manufactured by making a slurry containing reinforcing material etc. into a round net type, long net type, flow-on type etc.
Since it is a continuous industrial production method, there is an advantage that a product of uniform and stable quality can be produced. Asbestos has been widely used as a reinforcing material, but in recent years, organic fibers have been increasingly used in place of asbestos to protect health. Has sufficient performance as a tile or a sizing material.

[0003]

In recent years, the concrete industry has been using some fly ash instead of cement in view of carbon dioxide emission control. The use of fly ash is considered to be significant because the paperboard uses cement in a particularly high ratio. However, when fly ash is used, in particular, when the manufacturing method is the Hatschek method, delamination often occurs to impair the physical properties of the sheet.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a high-strength board without causing delamination in a Hatschek papermaking method in which a hydraulic material represented by cement is replaced with fly ash at a high rate. It provides a means.
That is, the present invention relates to fly ash 15
-40 mass%, silica fume 1-10 mass%, fineness 1.5-5.0 dtex, fiber length 4-10 mm, strength 10c
N / dtex or more, containing 1 to 3% by mass of vinylon fiber for reinforcement having an elongation of 4 to 10%, 1 to 5% by mass of pulp of CSF 70 to 130, and the balance being a solid material mainly composed of hydraulic material. This is a method for forming a hydraulic material by forming a suspension of 4 to 7% by mass, preferably containing 0.3 to 2.0% by weight of sepiolite in combination with or replacing with silica fume in the solid content material. This is a method of making a hydraulic material made from a solid material. Further, the maximum bending strength P (MPa) of the standard molded body obtained by the above-mentioned papermaking method according to the standard test method is 25 or more, and when the deflection in the strength is L (cm), the product of P and L is 2.0.
The present invention relates to a hydraulic material sheet molding.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a rational production method using a mixture in which cement is replaced in large amounts by fly ash in the production of a paper-molded article using vinylon fibers as a reinforcing material by a round mesh method.

The particle size of fly ash is preferably 2600 cm ² / g or more in terms of Blaine value. The amount of fly ash added is 15 to 40% by weight. If the amount is less than 15% by weight, the papermaking property is reduced. If the amount is more than 40% by weight, the dispersion state of pulp and vinylon fibers is deteriorated. Fly ash is said to be effective in suppressing the alkali-aggregate reaction and maintaining long-term durability when used in concrete or mortar. Even if those features are passed on to the paper as a performance in the cured product, the actual problem is that when the paper is made from a formulation containing a large amount of fly ash, the hydration reaction is slower than that of cement, so the The phenomenon of low stickiness appears. Therefore, the adhesiveness between the layers is reduced, and the basic strength is often impaired.

[0007] Therefore, it is preferable to add a substance that increases tackiness. Sepiolite is effective as such. Sepiolite S _i O ₂ is 50 wt% strength approximately,
M _g O is mineral fine fibrous mainly composed of 20 wt% strength, fiber length 10μm approximately, a diameter of about 0.5 to 1.
0 μm and specific gravity 2.3. It has an excellent function of retaining a large amount of hydrated cement particles on the surface. The effect is exhibited when the added amount of sepiolite is 0.3 to 2.0%. Preferably 0.4% to 1.8%, more preferably 0.5% to 1.5%
It is.

However, in the case of sepiolite, although delamination is prevented, there is no effect of improving the reinforcing property. The present inventors believe that this is because sepiolite is not hydraulic and, in combination with the presence of a large amount of fly ash between layers, a kind of fine cold joint is produced. Therefore, when sepiolite is added, it is necessary to take measures to improve the strength.

The present inventors have studied a method for preventing delamination and at the same time improving the reinforcing property, and have found that the use of silica fume is effective.

[0010] Silica fume has a particle size of 0.1 to 0.3.
It is a micron fine particle, and the hydration reaction is slower than cement but faster than fly ash. Precisely reacts immediately with the hydration reactant of the cement to produce a new hydration reaction. Therefore, it is considered that the occurrence of the cold joint can be suppressed.

Further, it is considered that the silica fume easily binds to the hydroxyl group of the vinylon fiber in an ionic bond and coats the vinylon fiber, thereby promoting the fixation of the vinylon fiber in the cement matrix. For this reason, it is estimated that the reinforcing effect and the toughness improving effect of the vinylon fiber can be effectively brought out.

The amount of silica fume added is 1% by mass to 10% by mass, preferably 2% by mass to 7% by mass, more preferably 3% by mass to 6% by mass based on the total solid content. When the amount is less than 1% by weight, the above effect is reduced and becomes practically meaningless. If it is more than 10% by weight, the adhesion between layers is reduced.

[0013] Silica fume is obtained from exhaust gas dust generated when metal silicon or ferrosilicon is produced in an electric arc furnace. Its composition is a majority (70 to 98% by weight) of amorphous S _i O _2, particle size 1μm or less, an average particle diameter of 0.1μm or so, the specific surface area of the BET method 20m
It is about ² / g and the specific gravity is about 2.2.

In order to suppress delamination, an effect is obtained by using sepiolite or silica fume alone. Only in the case of silica fume, the effect of increasing the strength of the papermaking plate is further recognized. Sepiolite has no strength-enhancing effect. The coexistence of silica fume and sepiolite is more effective. In that case, the ratio of silica fume to sepiolite is preferably in the range of 1: 0.3 to 1: 0.1.

The vinylon fiber used in the present invention has a fineness of 1.5 to 5.0 dtex, a fiber length of 4 to 10 mm,
Fiber strength is 10 cN / dtex or more and elongation is 4 to 10%. When the fineness is smaller than this, the fracture mode is mainly used and the toughness is inferior in terms of the load applied per fiber.
If the fineness is larger than this, the papermaking property is reduced. If the length of the fiber is smaller than this, the fiber is mainly pulled out, and the reinforcing property is reduced. If the length of the fiber is longer than this, the yarn breaking mode becomes dominant and the toughness decreases. Fiber strength is 10cN /
If it is not less than dtex, a sheet having sufficient strength cannot be realized. In particular, when the maximum bending strength P (MPa) is 25 or more and the deflection in the strength is L (cm), it is more preferable to manufacture a high toughness plate in which the product of P and L is 2.0 or more. Is 12 cN / dtex or more, more preferably 14 cN / dtex or more. Elongation is 4
A range of 10% to 10% is necessary to properly balance breakage and dropout.

The amount of fibers mixed is 1 to 3% by mass, preferably 1.5 to 2.5% by mass. Further, in order to produce a high toughness plate for the same reason as above, the content is preferably 2.0% by mass or more. If it is less than 1% by weight, the strength of the papermaking plate is low. If the content is more than 3% by weight, the papermaking property is deteriorated.

At the time of papermaking, first, cement, fly ash, silica fume, sepiolite and water are mixed,
After stirring, pulp and vinylon fibers are added and further stirred to obtain a slurry. This is usually performed using a stirring tank called a pulper, and the solid content concentration at this time is preferably 20 to 10% by mass, particularly preferably 17 to 12% by mass. If the density is higher than this, the dispersion state of the pulp and vinylon fibers becomes worse. If it is thinner than this, the subsequent papermaking properties will decrease.

Subsequently, this slurry is led to a stirring tank and a fixed-quantity feeding device called a chest. From here, it is quantitatively supplied to Vat which is a papermaking tank. In the process, water is supplied and diluted appropriately to adjust the concentration to a level suitable for Vat papermaking. Its concentration is in the range of 4 to 7 mass% solids. If it is thinner than this, the papermaking efficiency decreases, and if it is higher than this, the papermaking plate becomes non-uniform, causing variations in strength.

The present invention is characterized in that vinylon is blended with reinforcing fibers, but other reinforcing fibers may be blended as long as the effects of the present invention are not impaired. That is, glass fiber, acrylic fiber, carbon fiber,
Fibers such as polynosic fibers, polyethylene fibers, polyester fibers, polyamide fibers, and aramid fibers may be added. The amount of these additives is 1% by mass or less / molded product, and more preferably 0 to 0.5% by mass / compound composition.

It is sufficient to mix such reinforcing fibers with a hydraulic material to obtain a molded article as a slurry, but a desired molded article cannot be obtained simply by using a specific reinforcing fiber. That is, the use of only the above-mentioned reinforcing fibers reduces the effect of retaining the hydraulic material particles, so that the density of the molded body is reduced and the mechanical performance is apt to be reduced. From the above, in the present invention, it is necessary to mix a specific pulp, specifically, CS
It is necessary to mix pulp of F70 to 130. CSF
When the CSF is less than 70, uniform formation cannot be obtained, and when the CSF exceeds 130, the hydraulic material particles cannot be sufficiently captured. By blending the pulp having the beating degree CSF value in the range, the hydraulic material particles can be sufficiently captured, and the sheet thickness can be increased, so that the production efficiency is improved and the machine can be operated for a long time. A molded article having high density and excellent strength and toughness can be obtained.

The pulp is preferably natural pulp or natural pulp to which various treatments have been added. Among them, wood pulp, particularly coniferous wood pulp is more preferable from the viewpoints of paper making property, hydraulic material particle trapping property and the like. . The added amount of pulp must be 1 to 5% by mass / molded article. When the added amount of pulp is small, the effect of capturing the hydraulic material particles becomes insufficient, and conversely, the added amount of pulp becomes too large. This also impairs the papermaking properties of the papermaking molded article and decreases the mechanical performance. In order to obtain the effects of the present invention more efficiently, it is preferable to set the blending amount of pulp to 2 to 4% by mass / mold. As the beating degree CSF value of the pulp is smaller, a sufficient hydraulic material particle trapping effect can be obtained even with a small addition amount, and the blending amount can be reduced.

In the present invention, the cement and fly ash may be mixed at the time of preparing the slurry, or a so-called fly ash cement in which ordinary Portland cement and fly ash are mixed in advance may be used. In addition, gypsum, gypsum slag, magnesia, and the like may be appropriately blended as the hydraulic material.

Other additives may be added as long as the effects of the present invention are not impaired. For example, fine particles such as silica flour, sodium bentonite, blast furnace slag, ball clay, aluminum hydroxide, and mica may be added as long as the effects of the present invention are not impaired. From the viewpoint of sufficiently obtaining the effects of the present invention, the amount of the inorganic fine particles is preferably set to 10% by mass or less / molded article.

The formed green sheet (unset sheet) is then squeezed with water by a press and subsequently cured to obtain a desired sheet. Press 2-10
The pressing may be performed at a pressure of MPa for a maximum of about 10 minutes, and the plate density is increased by pressing and the strength is improved. When the pressing is not performed, the density is reduced to about 1.2 to 1.4, the strength is reduced, and the deflection is increased. Such a low-density product is suitable for corrugated sheet processing or the like. However, from the viewpoint of bending strength, durability, and the like, the density of the molded body obtained by pressing at the above-described press pressure is about 1.5 to 1.8 g / cm ³ , particularly 1.6 to 1.8.
g / cm ³ is preferred. On the other hand, when the strength increases due to the increase in the density, the deflection decreases. However, the method according to the invention provides in each case a plate with a good balance of strength and deflection.

That is, the molded article obtained by the present invention is excellent in strength and toughness, and the specific performance is slightly different depending on the papermaking method, blending, etc., for example, standard papermaking using the slurry used in the method of the present invention. When a standard test body is manufactured by the method, when the maximum strength is P (MPa) and the deflection when the maximum strength is obtained is L (mm), 25 <
It is P, and it is possible to exhibit excellent toughness where P × L exceeds 2.0.

The form of the papermaking molded article is not particularly limited.
For example, it can be used in various applications by forming it into a plate shape. The molded article of the present invention can be made into various products, and can be widely used as, for example, roof tiles, sizing materials, water tanks, pipes, and the like. Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to the examples.

[0027]

[Example] [Fineness dtex] The apparent fineness was measured at n = 5 or more by measuring the weight of a given test length of the obtained fibrous material.
The average was determined. In addition, the fineness could not be measured by measuring the weight of a certain yarn length (fine denier fiber) was measured by a vibroscope.

[Fiber strength cN, strength cN / dtex, elongation%] The fibers are allowed to stand in an atmosphere of a temperature of 20 ° C. and a relative humidity of 65% for 24 hours to adjust the humidity.
The fiber strength was measured with an Instron tester “Autograph manufactured by Shimadzu Corporation” at 0 cm and a tensile speed of 5 cm / min.
The strength was obtained by dividing the strength by fineness. The elongation was calculated by elongation at break of single fiber (cm) / gripping length (cm) × 100. If the fiber length is shorter than 10 cm, the maximum length of the sample within the possible range is measured as the grip length.

[Freeness (CSF) ml] Pulp freeness test method The average value corrected to a slurry concentration of 0.3% by weight and a temperature of 20 ° C. in accordance with JIS P8121-1976 Canadian standard type was used. Ml with a precision of 1 ml as freeness
Expressed in units of

[Deflection (δ) cm indicating the maximum bending strength (P) MPa and the maximum bending strength P] A standard molded body was manufactured from the hydraulic material slurry by the following standard papermaking method.
Eight days later, the test specimen was subjected to a bending test by the central loading method under the following conditions, and the bending stress at the time of generating the maximum load was evaluated as the maximum bending strength, and the deflection showing the maximum bending strength in the load-deflection curve was evaluated as δ. Standard papermaking method: Formed by a round mesh papermaking method by Hatschek, 13 papermaking sheets are wound around a making roller, pressed and squeezed at a pressure of 5 MPa, and cured for 24 hours at 50 ° C. and a saturated humidity condition. Cured under the conditions of ° C. and saturated humidity to obtain a molded article of hydraulic material. Bending test: Apparatus Autograph AG5000-B manufactured by Shimadzu Corp. Sample Cut out to a size of 25 mm in width, 4 mm in thickness, and 10 cm in length, but cut out with the papermaking direction as the length direction and 4 ± 0.5 mm in thickness. Is used as a specimen without cutting out. Test speed 2mm / min 3-point bending span 5cm

[Examples 1-4, Comparative Examples 1-2] 500 liters of water was put into a preliminary stirrer (pulper), the stirrer was stirred, softwood pulp (CSF 120 ml) was added, and then reinforcing fibers and other Was added in order as needed to obtain the compounding amount shown in the table, and after sufficient stirring, the obtained slurry having a concentration of 19% by mass was transferred to another feed tank (chest). Next, the slurry was supplied from the feed tank to the round mesh portion into the Vat to perform papermaking. V
Water was poured along the route up to at to adjust the solid content concentration in Vat to 5% by mass. Next, the obtained 13 sheets are wound around a making roller, pressed and squeezed at a pressure of 7.3 MPa, cured for 24 hours at 50 ° C. and saturated humidity, and further cured at 20 ° C. and saturated humidity. A molded article of hydraulic material was obtained. The obtained molded body has a thickness of 3.90 to
It is a slate plate having a size of 4.20 mm and a density of 1.50 to 1.58 g / cm ³ , and the performance of such a molded product is shown in Table 1. We also made a press-less plate separately. After curing, this plate had a thickness of 4.70 mm and a density of 1.35 g / cm ³ .

The ordinary cement is ordinary Portland cement manufactured by Chichibu Onoda, fly ash is second-class fly ash manufactured by Kanden Kyokai, fly ash cement is fly ash cement manufactured by Chichibu Onoda Cement, and silica fume is Union Chemical Co., Ltd. EFACO SILICA manufactured by
The pulp used was Canadian softwood CSF = 120, and the blending amount was as follows. Reinforcing fiber 2% by mass described in Table 2 Fly ash Described in Table 2 Silica fume described in Table 2 Pulp 3% by mass Sepiolite Described in Table 2 Cement Described in Table 2

[0033]

[Table 1]

[0034]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 18/08 ZAB C04B 18/08 ZABZ 22/06 22/06 A // (C04B 28/04 C04B 18: 08 18:08 22:06 22:06 16:06 A 16:06 E 16:02 Z 16:02 14:10 B 14:10) F term (reference) 4G012 MA01 PA15 PA22 PA24 PA26 PA27 PE02 PE03 4G052 EA01 EA06 EA09 EB02

Claims (3)

[Claims] 1. A fly ash of 15 to 4 with respect to a total solid content.
0% by mass, silica fume 1 to 10% by mass, fineness 1.5
~ 5.0dtex, fiber length 4 ~ 10mm, strength 10cN / d
tex or more, a vinylon fiber for reinforcement having an elongation of 4 to 10% is 1 to 3% by mass, and a pulp of CSF 70 to 130 is 1 to 5%.
A method for producing a hydraulic material, comprising: preparing a suspension of 4 to 7% by mass of a solid material containing 1% by mass, and the remainder being mainly a hydraulic material. 2. The method of using sepiolite in combination with silica fume or replacing silica fume with 0.3 to 2.
2. The papermaking method according to claim 1, comprising 0% by mass. 3. The maximum bending strength P (M) obtained by the papermaking method according to claim 1 or 2 and obtained by a standard test method for a standard molded body.
Pa) is 25 or more, and the deflection in the strength is L
A molded article of a hydraulic material having a product of P and L of 2.0 or more when (cm).