JPH07109163A - Production of hydraulic composition and production of extrusion-molded article of hydraulic composition - Google Patents

Abstract

PURPOSE:To provide a production method capable of largely widening the extrusion width of the extrusion molding of a hydraulic composition, excellent in crack resistance of the extrusion-molded article, and enabling the increase of the strengths of the width direction and the extrusion direction of the article and the reduction of their variations. CONSTITUTION:At first, coarse silica powder having average particle diameter of >=100mum and a mixture of pulps are mixed and stirred to open the pulps. Then, this is compounded with fine silica powder, a hydraulic inorganic material and a reinforcing material and dispersed. The dispersed mixture is further compounded with an emulsion of an acrylic polymer containing carboxylic groups in the molecule and having an alkali-thickening property and mixed to obtain the hydraulic composition. In the extrusion molding apparatus, a taper-shaped flowing way 2 is placed between the front end 1a of a cylinder and a nozzle 3 and further a buffleplate 4 is placed at the boundary between the nozzle 3 and the taper-shaped flowing way 2. The buffleplate 4 serves to widen a hydraulic composition and at the same time homogenize the flow of the hydraulic composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hydraulic composition and a method for producing an extruded product using the same, and more specifically, for extruding a hydraulic composition containing a reinforcing material. In addition, the extruded product can be significantly widened, and at the same time, it has good mechanical strength and surface smoothness. In particular, it can be used for building wall materials, roof materials, floor materials, civil engineering panels, and troughs. The present invention relates to a method for producing a hydraulic composition that is effective when applied to the production of hydraulic plate materials such as the above, and a method for producing an extrusion molded article using the same.

[0002]

2. Description of the Related Art Asbestos has been widely used as a reinforcing material for hydraulic inorganic substances such as cement and gypsum. However, recently, asbestos pollution has become a problem, so instead of this asbestos, for example, inorganic fibers such as glass fiber, carbon fiber, rock wool; polyacrylonitrile-based,
Organic synthetic fibers such as polyolefin and polyvinyl alcohol; natural organic fibers such as hemp and wood pulp; mica,
Studies are being conducted to put powders such as talc, chlorite, calcium carbonate, kaolin, clay and wollastonite into practical use as a reinforcing material.

However, the above-mentioned reinforcing material is
Both of them have a larger diameter than asbestos, and since their water retention and hydrophilicity are small, when extruding a hydraulic composition containing these reinforcing materials, there is a problem that smooth extrusion is difficult to achieve. is there. Such a problem can be solved to some extent by adding a large amount of a cellulose derivative such as methyl cellulose to the hydraulic composition.

However, addition of a large amount of a cellulose derivative not only adversely affects the hydraulic property in the process of extrusion molding and the performance of the extrusion molded product, but also the cellulose derivative is expensive, so that the production cost of the obtained product is high. The problem arises that it will be raised significantly. In order to solve such a problem, for example, JP-A-2-2297
Japanese Unexamined Patent Publication No. 48 discloses a method in which polyacrylic acid or a derivative of polyacrylic acid and zinc white, or a mixture of polyacrylic acid or a derivative of polyacrylic acid and aluminosilicate glass are mixed and extruded.

In the case of this method, a certain degree of effect can be expected for a hydraulic composition containing asbestos having high water retention and hydrophilicity. However, in the case of asbestos-free, the water-holding property and the tackiness of the hydraulic composition are not sufficient, so that the molding pressure at the time of extrusion molding is unavoidably low, and as a result, the obtained molded product is obtained. However, there arises a problem that the shape retention property and the surface smoothness are deteriorated.

Further, JP-A-4-144949 discloses an asbestos-based cement extrusion molding admixture comprising a cellulose derivative and a copolymer of acrylamide. However, since this admixture is not an emulsion of a polymer exhibiting an alkali thickening property, it has a high viscosity when added to a hydraulic composition and does not sufficiently penetrate into the spaces between the components of the hydraulic composition to be extruded. As a result, the shape retention and surface smoothness of the obtained molded product deteriorate, and the mechanical strength decreases.

On the other hand, when a wide cement fiber-containing cement board is extrusion-molded by an extruder, the flow of the cement material in the die can be reduced by inserting and removing the adjusting block from below into the die of the extruder. It is generally practiced to regulate by a block and thereby perform extrusion molding as a wide plate body. However, in this method, there is a problem that since the flow controllable region is narrow, the width can be increased only to about 2 to 3 times the cylinder width of the extruder used. Further, in the case of this method, since the flow of the cement material is blocked by the block, a turbulent flow is generated in the cement material, and the plate material after extrusion molding may meander.

[0008] In order to solve such a problem, actual Kaihei 1-644
No. 03 discloses a die having a structure in which a tapered flow path is formed in a nozzle attached to the tip of a cylinder, and a rectifying plate is arranged in the entire flow direction of the tapered flow path in the flow direction to widen the cement material. Has been done. With this die, the material flow to be extruded becomes uniform. However, the plate material obtained after extrusion molding tends to have cracks in the extrusion direction at the time of post-processing. This is because the length of the straightening vanes arranged is long, so even when the materials divided by the straightening vanes merge again at the outlet of the nozzle after widening, the state of mutual binding between the divided materials is bad. Because it will be.

Further, in the case of this method, since the cement material discharged from the cylinder is divided by the long rectifying plate, the molding pressure at that time naturally becomes high, so that a large load is applied to the extrusion molding apparatus. It becomes easy to take. To solve this problem, Japanese Utility Model Laid-Open No. 60-51012 discloses a horizontal flow straightening plate and a vertical flow straightening plate having a streamlined sectional shape in the extrusion direction and a short length in a tapered flow path. Then, a short tube having a structure of widening is disclosed.

By using the short tube of this structure, the condition of mutual binding between the divided materials is improved, and the load on the extruder is reduced as compared with the above-mentioned prior art. However, dividing the material with multiple straightening vanes is no different from the case of the prior art,
The molding pressure is still high, and the load on the extruder is not significantly reduced. At the same time, the material discharged from the cylinder is affected by the width expansion, and the bending strength of the obtained plate-shaped material in the width direction becomes lower than the bending strength in the extrusion direction.

Thus, if the effect of widening the hydraulic composition such as cement material is emphasized at the time of extrusion molding, the obtained plate material may be cracked in the longitudinal direction at the time of post-processing, or may be extruded. The molding pressure of the machine rises. Then, due to the influence of the material discharged from the cylinder being widened, the bending strength of the obtained plate material in the width direction becomes significantly lower than the bending strength in the extrusion direction.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in extrusion molding a hydraulic composition containing a reinforcing material so that even if the molding pressure is low, the water being extruded is extruded. The hard composition can be significantly widened as compared with the conventional one, the flow can be uniformly controlled, and the bending strength in the width direction and the extrusion direction of the obtained extruded product can be uniform and increased. It is intended to provide a method for producing a hydraulic composition for molding and a method for producing an extruded product of the hydraulic composition.

[0013]

In order to achieve the above object, in the present invention, 5 to 25% by weight of fine silica having an average particle size of 20 μm or less and 10 to 30% by weight of coarse silica having an average particle size of 100 μm or more. % And hydraulic inorganic material 10
0 to 5 parts by weight of pulp, and 0.5 to 5 parts by weight of pulp, and an emulsion of an acrylic polymer having a carboxyl group in the molecule and having an alkali thickening property are converted into the weight of the acrylic polymer. When producing a hydraulic composition by blending 0.1 to 0.5 parts by weight, the coarse silica and the pulp are mixed and stirred to defibrate the pulp, and then components other than the emulsion are added. A method for producing a hydraulic composition is provided, which comprises mixing and dispersing the resulting emulsion, and further adding and mixing water in which the emulsion is dispersed, and extrusion molding the hydraulic composition. When
As the extrusion molding device, an extrusion molding device in which a tapered flow path is interposed between the tip of the cylinder and the nozzle, and a resistance plate is arranged at the boundary between the nozzle and the tapered flow path is used. A method for producing an extruded product of a hydraulic composition, characterized in that the hydraulic composition is widened by the resistance plate and the flow of the hydraulic composition is made uniform.

The hydraulic composition for extrusion molding produced in the present invention is composed of the above-mentioned components as essential components, and the characteristic of the production method is that the mixing procedure of each component is defined. First, the main raw material of a hydraulic composition is a hydraulic inorganic material composed of a calcareous raw material and a siliceous raw material.

Examples of the calcareous raw material constituting one of the main raw materials include plain cement such as Portland cement and alumina cement; mixed cement such as blast furnace cement; special cement such as expanded cement. . Examples of the other siliceous raw material include crystalline silica such as silica sand and silica powder; non-crystalline silica such as fly ash, silica fume, blast furnace slag, and diatomaceous earth. .

Regardless of whether crystalline silica or amorphous silica is used, in the hydraulic inorganic material used in the present invention, 5 to 5 fine silica particles having an average particle size of 20 μm or less are used.
25% by weight and 1 of coarse silica with an average particle size of 100 μm or more
It is necessary to contain 0 to 30% by weight. As described below, the coarse silica is first agitated with the pulp at a high speed during preparation of the hydraulic composition, and at this time, the coarse silica penetrates into the spaces between the single fibers of the pulp. Defibrate the whole pulp to the level of single fiber.

As a result, fiber ballization of pulp at the time of kneading the entire hydraulic composition is prevented as much as possible, and uniform kneading of the whole progresses, so that the strength contribution ratio of the pulp to the strength of the extruded product increases. The effect is obtained. With silica having an average particle size of less than 100 μm, the above effects cannot be sufficiently exhibited. Further, when the amount of coarse silica used is less than 10% by weight as the content in the obtained hydraulic inorganic material, defibration of the pulp and uniform dispersion of the both do not proceed sufficiently, and as a result, The strength and explosion resistance of the extruded product are not so improved. When the amount of coarse silica used for defibrating the pulp is more than 30% by weight as the content in the hydraulic inorganic substance, defibration of the pulp proceeds but the mechanical strength of the obtained extrusion molded article is increased. Can not be expected to improve significantly. For this reason, the amount of coarse silica having an average particle diameter of 100 μm or more is limited to 10 to 30% by weight, preferably 15 to 25% by weight as the content in the hydraulic inorganic substance.

On the other hand, fine silica having an average particle diameter of 20 μm or less contributes to the improvement of the mechanical strength and the explosion resistance of the extruded product when used in combination with the above-mentioned coarse silica. Also,
When used in combination with an emulsion of an acrylic polymer described below, it contributes to the improvement of the shape retention and surface smoothness of the extruded product. When the content of the fine silica in the hydraulic inorganic material is less than 5% by weight, the above effects are not sufficiently exhibited, and when it is more than 25% by weight, the explosion resistance of the extruded product is deteriorated. Will be triggered. The preferable content in the hydraulic inorganic material is 12 to 2
It is 0% by weight.

Although these silicas are usually amorphous particles, it is preferable to use one having an angular shape rather than one having a round shape. Particularly, coarse silica is effective because it promotes defibration of pulp.
The mixing ratio of the calcareous raw material and the siliceous raw material at the time of preparing the hydraulic inorganic substance is not particularly limited, but usually the former is about 0.5 to about 1.2 times the amount of the latter 1 part by weight. Mixed in the range of.

As a reinforcing material to replace asbestos, for example,
Inorganic fibers such as glass fiber, carbon fiber and rock wool;
Examples thereof include organic synthetic fibers such as polyacrylonitrile-based, polyolefin-based, and polyvinyl alcohol-based; organic natural fibers such as hemp and wood pulp; fibrous powders such as wollastonite, potassium titanate, and edenite. The amount of addition at that time is 100 for the hydraulic inorganic material described above.
The amount is 1 to 30 parts by weight, preferably 5 to 20 parts by weight, based on the weight. If the amount added is too small, a sufficient reinforcing effect on the extrusion molded article cannot be obtained, and if it is too large, the molding pressure during extrusion molding becomes extremely high, and as a result,
This is because the surface quality of the extruded product begins to deteriorate.

During the preparation of the hydraulic composition of the present invention, pulp is incorporated as an essential component among the above-mentioned various reinforcing materials. This pulp may be any aggregate of cellulose fibers, such as hardwood pulp, softwood pulp, waste paper pulp, hemp, and bamboo pulp. The blending amount of this pulp is 10
It is set to 0.5 to 5 parts by weight with respect to 0 parts by weight. If the compounding amount is less than 0.5 parts by weight, the effect of improving the explosion resistance of the obtained extrusion molded article becomes small, and if it is more than 5 parts by weight, it is difficult to uniformly disperse it in the hydraulic composition. As a result, the mechanical properties of the extruded product tend to deteriorate. The preferable blending amount of pulp is 1 to 3 parts by weight based on 100 parts by weight of the hydraulic inorganic material.

Of these reinforcing materials, wollastonite is a preferable reinforcing material. When wollastonite is used as a reinforcing material, it is 1 to 30 parts by weight, or 5 to 20 parts by weight, depending on 100 parts by weight of the above-mentioned hydraulic inorganic material.
It is preferable to include the amount by weight. When the hydraulic composition is prepared, a water-soluble cellulose derivative and an emulsion of an acrylic polymer described later are further added.

First, the water-soluble cellulose derivative imparts water retention property to the hydraulic composition at the time of extrusion molding, and functions to enhance the binding force between the respective components. Examples of such water-soluble cellulose derivatives include methyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl ethyl methyl cellulose and the like. Each of these may be used alone or in combination of two or more.

The amount of the cellulose derivative added is 0.1 parts by weight based on 100 parts by weight of the above-mentioned hydraulic inorganic material of the hydraulic composition.
It is preferably 3 to 3 parts by weight. Particularly preferably, it is set to 0.5 to 1 part by weight with respect to 100 parts by weight of the hydraulic inorganic material. If this addition amount is too small, it may not be possible to impart sufficient water retention to the hydraulic composition, and conversely, if it is too large, the fluidity of the hydraulic composition will decrease, and the resulting extrusion The explosion resistance of the molded product is reduced.

Next, in the acrylic polymer emulsion, when the above-mentioned water-soluble cellulose derivative is dissolved in water, the viscosity is remarkably increased, and it is difficult for the emulsion of the water-soluble composition to permeate between the respective components of the hydraulic composition. Work. The acrylic polymer used has a carboxyl group in the molecule,
In addition, it exhibits alkali thickening. Naturally, it is insoluble in water and forms an emulsion with water.

Here, the alkali thickening means that the emulsion comprising the acrylic polymer and water is neutralized when it is brought into contact with, for example, an alkali of cement, that is, an alkali having a pH of 9 to 13, and the acrylic polymer is converted into water. It is the property of becoming soluble and increasing the viscosity of the emulsion. Since this acrylic polymer emulsion has a low viscosity, it penetrates into the spaces between the various reinforcing materials and admixtures constituting the hydraulic composition, and after thickening with the alkali of the hydraulic inorganic material, By the synergistic effect with the cellulose derivative as an additive component, the lubricity and the adhesive force between the respective components are increased, thereby enabling smooth extrusion molding.

Examples of the acrylic polymer having such a function include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, and acrylic acid ester, methacrylic acid ester and itacone. Acid ester, maleic acid ester, vinyl acetate,
Examples thereof include copolymers with vinyl monomers such as styrene and acrylonitrile.

In the above-mentioned copolymer, each of the unsaturated carboxylic acid and vinyl monomers is 2
It may be a copolymer of two or more species. Of the above-mentioned unsaturated carboxylic acids, acrylic acid or methacrylic acid is preferable because it can synthesize a high molecular weight acrylic polymer or an acrylic polymer having a high alkali thickening property.

The copolymerization amount of the unsaturated carboxylic acid in the acrylic polymer is preferably 3 to 80% by weight, and particularly preferably 30 to 60% by weight. When the copolymerization amount of unsaturated carboxylic acid is out of the above range,
The alkali thickening of the obtained acrylic polymer becomes difficult to improve. Alternatively, it becomes difficult to form a stable emulsion.

In order to impart water retention to the acrylic polymer, for example, two kinds of monomers having a functional double bond in the molecule, such as divinylbenzene, divinyl ether, divinyl ketone and divinylmethane, are used. The above may be copolymerized. In that case, the method for copolymerizing the monomers is not particularly limited, and a normal polymerization method,
For example, emulsion polymerization can be applied.

Examples of the emulsifier for emulsifying the monomer include anionic interfaces such as fatty acid salts, higher alcohol sulfate ester salts, fatty acid amine sulfate salts, aliphatic alcohol phosphate ester salts and alkylallyl sulfonate salts. Examples thereof include activators and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, and sorbitan alkyl esters. As the polymerization initiator, in addition to known peroxides, usual radical polymerization initiators such as redox catalysts can be used.

As for the molecular weight of the acrylic polymer to be used, the higher the molecular weight is, the more the alkali thickening property is increased. On the other hand, if the molecular weight is too high, the stability of the emulsion is deteriorated. The weight average molecular weight is preferably set in the range of 500,000 to 2,000,000. The amount of the acrylic polymer added is 0.05 to 20 with respect to 100 parts by weight of the hydraulic inorganic material.
It is preferably part by weight. Particularly preferably, it is 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the hydraulic inorganic material.

If the amount added is too small, sufficient alkali thickening will not be exhibited, and it will be difficult to achieve good shape retention and surface smoothness of the extruded body. This is because the molding pressure at that time becomes high and stable extrusion molding becomes difficult to perform. In order to permeate the water-soluble cellulose derivative described above into the spaces between the components of the hydraulic composition, in addition to the emulsion described above, a sulfonate or carboxylate of an aliphatic polymer, particularly a conjugated diene. It is preferable to use a sulfonate of a polymer as a penetrant.

In addition, a hydraulic inorganic material, for example, a lubricant such as talc, mica, chlorite, etc., which improves the fluidity (moldability) of the hydraulic composition during extrusion molding; extrusion molding Inorganic minerals such as sepiolite, bentonite, and zeolite, super water-absorbent resins such as acrylic polymers and starches, which improve water retention at the time; perlite, shirasu balloon, glass balloon, which makes the extruded product lightweight. Synthetic resin foam beads may be added.

In producing the hydraulic composition of the present invention,
First, coarse silica and pulp are put into a mixer and the whole is stirred at high speed to defibrate the pulp, and at the same time, both are uniformly dispersed and mixed. Next, the calcareous raw material, which is another component of the hydraulic inorganic material, fine silica, and other components such as a reinforcing material are added thereto and the whole is mixed. Thus,
A powder mixture is obtained which is defibrated until the pulp is monofilament.

Then, water in which the above-mentioned emulsion is dispersed is added to this powder mixture and the whole is kneaded.
In the obtained kneaded product, generation of fiber balls of pulp was suppressed, and the emulsion permeated into the gaps between the components to improve the binding force between the components, and the fluidity was also in a good state. is there.

In the present invention, the hydraulic composition produced as described above is extruded to produce an extruded product having excellent mechanical strength. 1 and II-II of FIG.
As shown in FIG. 2 which is a cross-sectional view taken along the line, in this extrusion molding apparatus, a nozzle 3 having a plurality of cores 3a incorporated therein is provided at the tip of a cylinder 1 via a tapered flow path 2 described later. Is installed. The boundary between the tapered flow path 2 and the nozzle 3 is partitioned by the resistance plate 4.

Here, the tip of the cylinder 1 is III in FIG.
As shown in FIG. 3 is a sectional view taken along -III line, diameter cross-sectional area by D ₁ has the discharge port 1a is S _1.
As shown in FIG. 2, the tapered flow path 2 widens toward the downstream side, reaches the maximum width at the point 2a, and thereafter narrows down to the boundary with the resistance plate 4. And point 2a
Cross-sectional shape in, as shown in FIG. 4 is a sectional view taken along line IV-IV in FIG. 2, the length in the width direction of the area in D ₂ S
_{It has} a rectangular shape of ₂ .

The resistance plate 4 is a sectional view taken along the line VV of FIG.
As shown in, the length in the width direction is D ₃And And Nakako
The area excluding the portion between 3a and its supporting portion 3a is S₃And
The cross-sectional shape is such that And finally, the dice
3 is shown in FIG. 6 which is a sectional view taken along line VI-VI of FIG.
So that the length in the width direction is D_FourAnd of the core 3a
Area excluding part is S_FourThe cross-sectional shape looks like
There is.

In the case of the extrusion molding apparatus of the present invention, the cylinder 1
Of the discharge port 1a, the tapered flow path 2, the resistance plate 4, and the nozzle 3.
In the above shape specifications, D₁~ D_FourBetween₂
> D ₃> D_Four> D₁Is satisfied, and S₁~ S
_FourBetween₂> S₃> S ₁> S_FourRelationship is met
As described above, extrusion channel of the kneaded product (hydraulic composition)
Is designed.

Therefore, since the kneaded product discharged from the discharge port 1a of the cylinder initially has S ₂ > S _1, it moves in the central portion of the width of the tapered flow path 2, but is smaller than S _2. When reaching the resistance plate 4 having a cross-sectional area (S ₃ ), the resistance flow of the resistance plate 4 causes the tapered flow path 2 to be filled with the width and made uniform. Since S ₄ has a smaller cross-sectional area than S _{3, the} kneaded material that is uniformly filled in the tapered flow path 2 is densified and at the same time becomes a uniform flow, which is desired by the die 3. It becomes a shape and is extruded.

As described above, by using the extrusion-molding apparatus having the above-mentioned structure, the hydraulic composition discharged from the cylinder can be spread in a uniform state, and therefore the molding pressure depends on the extrusion speed of the kneaded product. It is irrelevant and low, and it is possible to reduce variations in strength in the width direction and extrusion direction of the extrusion molded body. The extruded body thus extruded is then cured and hydrated and cured.

At this time, the extrusion-molded body is a plate-shaped product by changing the die of the extrusion-molding apparatus to a desired die.
It may have any shape such as a columnar shape or a cylindrical shape. As the curing method, natural curing, steam curing, autoclave curing, or a combination thereof may be adopted depending on the type of the extruded product.

[0044]

Examples of the invention

Example 1 65 parts by weight of Portland cement, average particle size 200 μm
17.5 parts by weight of silica sand, and A-3 silica (trade name,
100 parts by weight of a hydraulic inorganic material having an average particle size of 2 μm and 17.5 parts by weight of Fuji Talc Co., Ltd. was prepared.

First, 17.5 parts by weight of the above silica sand and pulp 1.
8 parts by weight were placed in an Erich mixer (manufactured by Nippon Erich Co., Ltd., Model RV-02) and stirred at a high stirring speed of 1400 rpm for 4 minutes. Next, 7.5 parts by weight of wollastonite, 7.5 parts by weight of talc, 0.5 parts by weight of polypropylene fiber having a fiber length of 6 mm, and Metroses 90.
1 part by weight of SH30000 (trade name, hydroxypropylmethylcellulose powder manufactured by Shin-Etsu Chemical Co., Ltd.) was added and the whole was mixed.

An emulsion of an acrylic polymer having a copolymerization amount of acrylic acid of 45% by weight (weight average molecular weight of about 800,000) was converted into an acrylic polymer based on the above hydraulic inorganic material in the obtained powder mixture. 28 parts by weight of water, which was dispersed in an amount of 0.2 parts by weight, was added to the hydraulic inorganic material, and the whole was kneaded with a kneader. On the other hand, D ₁ : 160 mm,
S ₁ : 201 cm ² discharge port, D ₂ : 700 mm, S ₂ : 7
00 cm ² , D ₃ : 630 mm, S ₃ : 18 cm ² , D ₄ : 6:
The above kneaded product was extruded using the extrusion molding apparatus shown in FIGS. 1 and ^{2 having} the specifications of 10 mm and S ₄ : 180 cm ² . The molding pressure at this time was 17 to 18 kg / cm ² . A hollow plate material having a width of 610 mm, a thickness of 60 mm, and a cross section of 58 hollow parts having a width of 58 mm and a height of 30 mm arranged in one row was obtained. That is, the width was expanded to about 4 times that of the discharge port 1a.

The hollow plate material thus obtained was subjected to primary curing for 4 hours under a saturated vapor pressure at a temperature of 70 ° C., and then at a temperature of 180 ° C.
The autoclave was aged for 9 hours under saturated vapor pressure to cure the hydration. Then, this hydrated cured product was cut out in the width direction and the extrusion direction to obtain a length of 150 mm and a width of 50, respectively.
mm, thickness 14 mm as a solid test body. Bending strength under absolutely dry condition of the test specimen (span length 10 cm) is, 251 kg / cm ² in the width direction was 258kg / cm ² in the extrusion direction.

Further, with respect to this extruded body, 70 ° C./mi
After heating to 700 ° C. at a temperature rising rate of n and holding at that temperature for 10 minutes, it was cooled to room temperature (about 20 ° C.) and the surface condition was observed to evaluate the explosion resistance. Although some cracks were observed on the surface, the extruded product remained in its original shape and almost no explosion occurred.

Comparative Example 1 A hollow plate material having the same size was extruded in the same manner as in Example 1 except that silica sand having an average particle diameter of 200 μm was not used and only A-3 silica was used as a siliceous raw material. Molded. The molding pressure at this time was 14 to 15 kg / cm ² . Curing was performed in the same manner as in the example, and the bending strength of the test piece was measured under the same conditions. 261 kg / cm ^{2 in} width direction, 266 kg in extrusion direction
It was / cm ² .

The extruded body was evaluated for explosion resistance under the same conditions as in the examples. Explosion occurred and the extrudate did not stay in its original shape at all. Comparative Example 2 A hollow plate material having the same size was extruded in the same manner as in Example except that an acrylic polymer emulsion was not used. The molding pressure at this time was 20 to 22 kg / cm ² .

Curing was performed in the same manner as in the example, and the bending strength of the test piece was measured under the same conditions. 234kg / c in width direction
m ² and 235 kg / cm ² in the extrusion direction. Comparative Example 3 No resistance plate was arranged, D ₄ : 300 mm, S ₄ :
A hollow plate material having a width of 330 mm and a thickness of 60 mm was extruded in the same manner as in the example except that a 114 cm ² die was used. The molding pressure at this time was 20 to 22 kg / cm ² . Curing was performed in the same manner as in the example, and the bending strength of the test piece was measured under the same conditions. In the width direction 208 kg / cm ^2, the extrusion direction was 256kg / cm ^2.

[0052]

As is apparent from the above description, according to the method of the present invention, it is possible to significantly widen and extrude a hydraulic composition at a low molding pressure, and the mechanical strength is high. Moreover, it is possible to manufacture an extruded product having excellent explosion resistance. This is because at the time of preparation of the hydraulic composition, the mixture of coarse silica and pulp is first stirred at a high speed to defibrate the pulp, and a predetermined amount of fine silica is blended, and the water-soluble cellulose derivative and acrylic are mixed. By adding an emulsion of a system polymer, the binding force between the respective components is increased and the fluidity is enhanced.

At the time of extrusion molding, a resistance plate is arranged at the boundary between the tapered flow path of the extrusion molding apparatus used and the die so as to make the flow of the hydraulic composition being extruded uniform and wide. It is also the effect of doing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a tip portion of an extrusion molding apparatus used in a method of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a sectional view taken along line VI-VI in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder of extrusion molding apparatus 1a Discharge port of cylinder 1 2 Tapered channel 2a Part of maximum width of tapered channel 2 3 Die 3a Core of die 3 4 Resistance plate

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Claims (3)

[Claims] 1. Fine silica having an average particle size of 20 μm or less 5
25% by weight, coarse silica with an average particle size of 100 μm or more 1
0.5 to 5 parts by weight of pulp to 100 parts by weight of a hydraulic inorganic material containing 0 to 30% by weight, and an emulsion of an acrylic polymer having a carboxyl group in the molecule and having an alkali thickening property. When producing a hydraulic composition by mixing 0.1 to 0.5 parts by weight in terms of the weight of the acrylic polymer, the coarse silica and the pulp are mixed and stirred to dissolve the pulp. A method for producing a hydraulic composition, which comprises adding components other than the emulsion, mixing and dispersing the mixture, and further adding and mixing water in which the emulsion is dispersed, after the fiber is finely divided. 2. The method for producing a hydraulic composition according to claim 1, wherein the acrylic polymer is a copolymer of acrylic acid or methacrylic acid. 3. When the hydraulic composition according to claim 1 or 2 is extrusion-molded, as an extrusion-molding device, a tapered flow path is provided between the cylinder tip and the nozzle, and Using an extrusion molding device in which a resistance plate is arranged at the boundary with the tapered flow path, the resistance plate widens the hydraulic composition and equalizes the flow of the hydraulic composition. And a method for producing an extrusion-molded body of the hydraulic composition.