JPH0796510A - Method for producing extruded product of hydraulic composition - Google Patents

Abstract

(57) [Summary] [Purpose] An extrusion molded product of a hydraulic composition containing a reinforcing material of asbestos, which has excellent shape retention and surface smoothness and high strength and high toughness. A method of smoothly extruding a body is provided. [Composition] In this production method, when a hydraulic composition containing a reinforcing material of asbestos is extruded, two kinds of surface tension difference of 20 dyne / cm or more are added to the hydraulic composition. It has a sea-island structure formed by mixing liquids, and
An emulsion containing a polymer substance soluble in the liquid is added to the liquid of the island component.

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 an extruded product of a hydraulic composition, more specifically, a wall material for construction,
The present invention relates to a method for producing an extrusion molded body of a hydraulic composition which is useful when applied to the production of roofing materials, flooring materials and the like, pipes, panels and troughs for civil engineering.

[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,
Practical use of synthetic fibers such as polyolefin and polyvinyl alcohol; organic natural fibers such as hemp, wood and bamboo pulp; powders such as mica, talc, chlorite, calcium carbonate, kaolin, clay and wollastonite as reinforcing materials The study to do so is underway.

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-57-209
Japanese Patent No. 866 discloses a method for producing an extruded product by adding and mixing methylcellulose and polyacrylamide to a cementitious material. In addition, JP-A-4-144
JP-A 949 proposes an asbestos-based cement extrusion admixture comprising a water-soluble or water-dispersible cellulose derivative and a water-soluble or water-dispersible acrylic polymer.

However, in all of these prior arts, an acrylic polymer is used by dissolving it in water. Therefore, it is difficult to achieve uniform dissolution during the dissolution process of these acrylic polymers in water.
The resulting liquid tends to be non-uniform. Moreover, when the acrylic polymer used has a high molecular weight, it is very difficult to dissolve it in water.

Further, since the viscosity of the obtained liquid is high, when it is added to a hydraulic composition such as cement, it does not sufficiently penetrate between the respective components, so that the binding force between the respective components can be sufficiently increased. However, as a result, there is a problem in that the extrudate obtained has poor shape retention and surface smoothness. Furthermore, JP-A-54-162721 discloses a method for producing an extrusion molded body of a cement composition by using an emulsion such as polyacrylic acid ester.

However, in this method, since carboxymethyl cellulose (CMC) or hydroxyethyl cellulose (HEC) is used as a thickening agent when emulsifying the polyacrylic acid ester, it was obtained by the interaction of the above polymers. The emulsion tends to aggregate and becomes non-uniform. The viscosity of the obtained emulsion is high, and the permeation between the components of the hydraulic composition is poor, so that the extrudate obtained has shape retention, surface smoothness, and mechanical properties. The effect of improving strength can hardly be expected.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems when extrusion-molding a hydraulic composition containing a reinforcing material for asbestos, and to provide a hydraulic composition for asbestos. It can be smoothly extruded, has high strength and high toughness,
An object of the present invention is to provide a method for producing an extruded product of a hydraulic composition, which is excellent in shape retention and surface smoothness.

[0009]

In order to achieve the above object, in the present invention, when a hydraulic composition containing a reinforcing material of asbestos is extruded, the hydraulic composition is , The sea-island structure is formed by mixing two kinds of liquids with a surface tension difference of 20 dyne / cm or more, and an emulsion containing a polymer substance soluble in the liquid is added to the liquid of the island component. A method for producing an extruded product of a hydraulic composition is provided.

First, the hydraulic composition of the present invention means
The main raw material is a calcareous raw material and a siliceous raw material which are hydraulic inorganic substances, and a reinforcing agent in place of asbestos and various admixtures are mixed therein. Examples of calcareous raw materials constituting one of the main raw materials include plain cements such as Portland cement and alumina cement; mixed cements such as blast furnace cement; special cements such as expansive cement.

Examples of the other siliceous raw materials include crystalline silica such as silica sand and silica stone powder; amorphous silica such as fly ash, silica fume, blast furnace slag, and diatomaceous earth. You can The mixing ratio of the calcareous raw material and the siliceous raw material when preparing the main raw material is not particularly limited, but is usually about 0.5 to about 1.2 times the former 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, wood, and bamboo pulp; fibrous powders such as wollastonite, potassium titanate, and edenite.

Of these reinforcements, wollastonite is the preferred reinforcement. When wollastonite is used as a reinforcing material, 1 part is added to 100 parts by weight of the main raw material.
-30 parts by weight, depending on the purpose, it is preferable to contain 5 to 20 parts by weight. Examples of the admixture to be added to the main raw material include, for example, lubricants such as talc, mica, and chlorite that improve the fluidity (moldability) of the hydraulic composition during extrusion molding; Inorganic minerals such as sepiolite, bentonite, and zeolite, super absorbent polymers such as acrylic polymers and starches that improve water retention during extrusion molding; perlite, shirasu balloons, glass balloons that reduce the weight of extrusion moldings , Foamed beads of synthetic resin;

In the method of the present invention, when the above hydraulic composition is extrusion-molded, the emulsion described below is further added as an essential component. At this time,
At the same time, it is preferable to add a cellulose derivative as a binder for the purpose of imparting water retention to the hydraulic composition and increasing the binding force between the components.

Examples of such cellulose derivatives include methylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, hydroxypropylethylmethylcellulose 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 100% as the main raw material of the hydraulic composition.
It is preferably 0.3 to 3 parts by weight with respect to parts by weight.
Particularly preferably, it is 0.5 to 100 parts by weight of the main raw material.
It is set to 1 part by weight.

If the amount added is too small, it may not be possible to impart sufficient water retention to the hydraulic composition.
On the contrary, if the amount is too large, the tendency of adversely affecting the curing of the hydraulic composition and increasing the manufacturing cost increases. The emulsion used in the method of the present invention is characterized by the following properties.

First, this emulsion is formed by mixing two kinds of liquids having a surface tension difference of 20 dyne / cm or more,
It has a sea-island structure as a whole. Surface tension difference is 20
Two kinds of liquids with dyne / cm or more are essentially incompatible. However, here, further, fatty acid salts, higher alcohol sulfuric acid ester salts, alkylallyl sulfonates, aliphatic amine salts, quaternary ammonium salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters. When such a known surfactant is coexisted, micelle particles are formed and stabilized to form an emulsion having a sea-island structure.

At this time, the emulsion formed is changed to a water-in-oil type (W / O) by changing the mixing ratio of the two kinds of liquids or selecting the kind of the surfactant appropriately.
Type) emulsion or an oil-in-water type (O / W type) emulsion. In the present invention, both emulsions can be used, but from the viewpoint of increasing the bonding strength between the components of the hydraulic composition and improving the shape retention of the extruded product obtained, a W / O type emulsion is used. Is preferably used.

When the emulsion used is a W / O type, the island component in the sea-island structure is water, and the sea component is an inert hydrophobic organic material such as paraffin, benzene or toluene, mineral oil or kerosene. It is a solvent. When the emulsion used is an O / W type, an island component,
The sea component is the reverse of the above. In the emulsion to be used, a polymer that is soluble in the liquid is incorporated in the liquid that constitutes the island component.

For example, in the case of a W / O type emulsion,
Water-soluble polymer substances are incorporated in the form of fine particles in water, which is an island component. In that case, the higher the molecular weight of the water-soluble polymer substance, the better the binding force between the components of the hydraulic composition, and the better the shape retention and surface smoothness of the extruded product. That is, one having a weight average molecular weight of 1,000,000 or more is usually used. Preferably 300
It is more than 10,000, and more preferably 5 to 15 million.

As such a water-soluble polymer substance, for example, one or a mixture of two or more water-soluble monomers such as acrylamide, methacrylamide, sodium acrylate and sodium methacrylic acid is polymerized. The thing can be mentioned as a suitable thing. In addition to the above water-soluble monomer, other water-soluble monomers such as maleic acid, itaconic acid, vinyl sulfonate and dimethylaminomethacrylate may be used in a small amount.

In that case, it is preferable that the average particle size of the water-soluble polymer substance incorporated into the island component (water) as fine particles is 5 μm or less. It is preferably 2 μm or less, more preferably 0.1 to 1 μm. If the particle size is larger than 5 μm, when added to the hydraulic composition, the emulsion cannot sufficiently permeate into the spaces between the respective components such as the main raw material, the reinforcing material, and the admixture, and as a result, between the components. This is because the bonding strength is not sufficiently high and the shape retention of the extruded product tends to be low.

The emulsion used in the present invention behaves as follows. The case of a W / O type emulsion will be described below. When this W / O type emulsion is diluted with, for example, water, the water-soluble polymer substance that was substantially insoluble or swollen in the island component (water) due to the solubility when incorporated into the island component. Dissolves on contact with a large amount of aqueous phase. As a result, this W / O type emulsion inverts to an O / W type emulsion. And
The phase inversion emulsion, that is, the water-soluble polymer substance, penetrates into the gaps between various reinforcing materials and admixtures that make up the hydraulic composition, enhances the bonding force between the components, and thus allows smooth extrusion molding. By making it possible, the effect of improving the shape retention property and surface smoothness of the extruded product, and further the mechanical strength is exhibited.

At this time, if the surface tension difference between the two kinds of liquids constituting the emulsion is less than 20 dyne / cm, the stability of the emulsion is poor and the above-mentioned phase transition of the emulsion does not occur promptly. The above-mentioned effects are diminished by the fact that the soluble polymer substance is less likely to dissolve. Therefore, the difference in surface tension between the two kinds of liquids needs to be 20 dyne / cm or more. It is preferably 30 dyne / cm or more, more preferably 40 dyne / cm or more.

Such a W / O type emulsion can be prepared as follows. That is, an aqueous solution of a water-soluble monomer as described above is dispersed in an inert hydrophobic organic solvent in the presence of a surfactant, and the water-soluble monomer is polymerized using an oil-soluble radical initiator. It can be obtained by proceeding the reaction.

Examples of the hydrophobic organic solvent used at this time include aliphatic carbon hydrogen, aromatic hydrocarbons, various vegetable oils and animal oils. In particular,
As mentioned above, paraffin, benzene or toluene, mineral oil, kerosene, etc. may be mentioned. The surfactant to be used may be any one as long as it can form a stable W / O type emulsion and, when the emulsion comes into contact with water, facilitates phase inversion of the emulsion into an O / W type emulsion, It is not particularly limited.
For example, sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene derivative, polyester-polyoxyethylene condensate and the like can be mentioned.

Examples of the oil-soluble radical initiator used in the above-mentioned polymerization reaction include azo compounds such as azoisobutyronitrile and organic peroxides such as benzoyl peroxide. The added amount of the W / O type emulsion synthesized in this way is
The amount of the water-soluble polymer substance incorporated in the island component (water) is preferably 0.05 to 2 parts by weight based on 100 parts by weight of the main raw material of the hydraulic composition. Particularly preferably, it is 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the main raw material.

If the amount added is too small, the above W /
The phase inversion from the O type to the O / W type is reduced, and it becomes difficult to achieve good shape retention and surface smoothness of the extruded product. On the contrary, if it is too large, the extrusion pressure during extrusion is high. This makes it difficult to perform stable extrusion molding. In the method of the present invention, first, a main raw material consisting of a calcareous raw material and a siliceous raw material, a reinforcing material in place of asbestos, various admixtures described above, and optionally a powder of a water-soluble cellulose derivative. For example, a mixture is prepared by mixing with an Erich mixer, an appropriate amount of water is added thereto, and the whole is stirred.
The amount of water added is usually 100 parts by weight of the above mixture,
It is set to 20 to 30 parts by weight.

In this case, it is preferable to add the above-mentioned emulsion in a state in which a predetermined amount thereof is dispersed in the above-mentioned water. At this time, the water-soluble polymer substance is dissolved in water, and the viscosity of the O / W type emulsion obtained as a result of phase inversion significantly increases, making it difficult to uniformly mix the emulsion with the hydraulic composition. May become.

In such a case, a part of the W / O type emulsion to be used is mixed with an emulsion which thickens with an alkali as a main raw material, for example, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid. It is preferable to use an alkali-thickening emulsion such as a copolymer with a vinyl monomer such as methacrylic acid ester or maleic acid ester.

When such a treatment is applied, mixing of the emulsion with the hydraulic composition is facilitated, and the extrusion molded article has improved shape retention and surface smoothness, and at the same time has high strength and high toughness. Because it will be. When the above-mentioned emulsion is added to the hydraulic composition, the polymer substance incorporated in the island component is diluted with water and starts to dissolve, and at the same time, the formed O / W type emulsion forms the hydraulic composition. It is preferable to permeate into the gaps between the components. If this emulsion is diluted with water and left to stand for too long, the dissolution of the polymeric substance reaches a steady state and the viscosity of the phase-inverted emulsion increases excessively, causing an increase in the viscosity between the components of the hydraulic composition. This is because the permeability to the gap is reduced.

Therefore, it is preferable to add to the hydraulic composition as soon as possible within 1 hour after dilution with water, or immediately after dilution. The hydraulic composition thus prepared is then extruded by, for example, a vacuum extruder. Then, the obtained extruded body is cured and hydrated and cured. At this time, the extrusion molded body can be formed into an arbitrary shape such as a plate-like material, a columnar material, or a cylindrical material by changing the die of the extruder to a desired die. Also,
As the curing method, natural curing, steam curing, autoclave curing, or a combination thereof can be adopted depending on the type of the extruded product.

[0033]

Examples of the invention

Example 1 100 parts by weight of a main raw material consisting of 65 parts by weight of Portland cement having an average particle size of 20 μm and 35 parts by weight of silica fine powder having an average particle size of 10 μm, 7.5 parts by weight of wollastonite having an average particle size of 20 μm, average 7.5 parts by weight of talc with a particle size of 5 μm, 1.8 parts by weight of pulp, 0.4 mm polypropylene fiber with a fiber length of 6 mm
1 part by weight and 1 part by weight of Metrolose 90SH30000 (trade name, hydroxypropylmethylcellulose powder manufactured by Shin-Etsu Chemical Co., Ltd.) were sufficiently mixed with an Eirich mixer (Model RV-02 manufactured by Nippon Eirich KK).

Next, a W / O type emulsion was formed by using two kinds of liquids having a surface tension difference of 47 dyne / cm, and polyacrylamide (weight average molecular weight of about 50) was formed in the island component.
An emulsion containing 0,000) fine particles (average particle size 2 μm) was diluted to a solid content of 0.1 parts by weight and a water content of 28 parts by weight, stirred, and immediately added to the above mixed powder. The whole was added and kneaded thoroughly with a kneader.

This extruded body was cut into a sample having a length of 500 mm, and the sample was allowed to stand still on an edge having a span length of 240 mm, and the amount of deflection at the center of the sample was measured to evaluate the shape retention.
The amount of deflection was 1.6 mm. No cracks were observed on the surface of the extruded product, and the surface smoothness was good. The extruded body was naturally cured for a whole day and night, then pre-cured in steam at 70 ° C. for 4 hours, then put in an autoclave and cured in steam at 180 ° C. for 5.5 hours.

The bulk density of the molded body after curing is 1.90 g / cm ³ ,
Bending strength (span length, 100 mm) and Charpy impact value under air-dry condition are 395 kg / cm ² and 3.1 kg-, respectively.
It was cm / cm ² . Comparative Example The emulsion used has a surface tension difference of 15 dyne / cm 2
An extruded body was produced in the same manner as in Example 1, except that the extruded body was composed of various kinds of liquids.

The amount of flexure of the obtained molded product was 3.4 mm, and some cracks were recognized on the surface. The surface smoothness was inferior to that of Example 1. The molded body was cured in the same manner as in Example 1. The bulk density of the molded body after curing is
1.91 g / cm ³ , flexural strength (span length, 100 mm) and Charpy impact value under air-dried condition are 330, respectively.
It was kg / cm ² and 2.6 kg-cm / cm ² .

[0038]

As is apparent from the above description, according to the method of the present invention, a hydraulic composition containing a reinforcing material of asbestos is extruded to have excellent shape retention and surface smoothness, and high Strength·
A highly tough extruded product can be produced. this is,
The hydraulic composition to be extruded has a surface tension difference of 20 dyne / c.
It has a sea-island structure consisting of a mixture of two liquids of m or more, and the effect of adding an emulsion containing a polymeric substance soluble in the liquid to the liquid of the island component is there.

That is, when this emulsion is added to the water-soluble composition, the polymer substance in the island component is rapidly dissolved in water and the phase is changed to an O / W type emulsion, and the O / W type emulsion is hydraulically set. It permeates into the gaps between the components of the composition, and as a result, it enhances the bonding force between the components and improves the lubricity, which enables smooth extrusion molding. The properties, and further the mechanical strength, are improved.

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Claims (1)

[Claims] 1. When extrusion-molding a hydraulic composition containing an asbestos-free reinforcing material, the hydraulic composition is mixed with two kinds of liquids having a surface tension difference of 20 dyne / cm or more. A method for producing an extrusion-molded body of a hydraulic composition, which comprises a sea-island structure and is formed by adding an emulsion containing a polymer substance soluble in the liquid to the liquid of the island component. .