JPH0796507A - 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 manufacturing a body is provided. [Composition] In this production method, an emulsion of fine particles of a polyelectrolyte having the following formula: χ (%) = 100 × (1-√ (D ₁₀ / D ₆ )) (wherein D ₁₀ , D ₆ represent the absorbance of the emulsion at 25 ° C. adjusted to pH 10 and pH 6, respectively, where the absorbance is the value measured 24 hours after pH adjustment). Add an emulsion with a degree of 40% or more.

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,
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.

However, in the case of this method, the cross-linking reaction of polyacrylic acid or its derivative may occur depending on the zinc white and aluminosilicate glass used together. As a result, the emulsion used gels and its viscosity increases significantly, or it is difficult to perform extrusion molding due to the influence of foreign substances such as zinc white and aluminosilicate glass, and the obtained extrusion molded article This causes a problem that the tissue tends to become nonuniform and the mechanical strength thereof is also reduced.

Further, Japanese Patent Laid-Open Publication No. 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, the emulsion disclosed herein has low hydrophilicity, poor water retention, and almost no thickening effect, so that the molding pressure during extrusion molding of a hydraulic composition such as a cement composition becomes high. At the same time, there is a problem that the effect of improving the shape retention and surface smoothness of the extruded product can hardly be expected.

[0007]

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.

[0008]

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 , An emulsion of fine particles of a polyelectrolyte, having the following formula: χ (%) = 100 × (1-√ (D ₁₀ / D ₆ )) (1) (wherein D ₁₀ and D ₆ are Represents the absorbance of the emulsion at 25 ° C. adjusted to pH 10 and pH 6, respectively, where the absorbance is the value measured after 24 hours of pH adjustment) and the alkali solubility is 40%. There is provided a method for producing an extrusion molded body of a hydraulic composition, which is characterized by adding the emulsion described above.

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, fillers such as calcium carbonate and carion that improve water retention during extrusion; Examples thereof include perlite, shirasu balloon, glass balloon, and synthetic resin foam beads, which are lightweight.

In particular, when a filler is blended, it is preferable to use fine particles having a particle size of 1 μm or less as the filler because the water retention effect can be enhanced. In the method of the present invention, the emulsion described below is further added as an essential component when the above-mentioned hydraulic composition is extrusion-molded. 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 enhancing the binding force between the respective 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 has a high content described below.
It contains fine particles of a child electrolyte. That is, this high
As a child electrolyte, the skeleton has an aliphatic structure,
Carboxyl group, sulfonic acid group, phosphoric acid group (-PO₃H
₂), A phosphite group (-PO ₂H₂) Has an acidic group such as
Polymer carboxylic acid, polymer sulfonic acid, polymer
Those linked as side groups such as acid and high molecular weight phosphorous acid
Can be raised.

Particularly, high molecular weight carboxylic acids are preferable, and among the high molecular weight carboxylic acids, for example, polyacrylic acid, polymethacrylic acid, and polymers such as maleic acid, itaconic acid and crotonic acid are preferable. Can be given as Further, polysaccharide derivatives such as carboxymethyl cellulose having a carboxyl group, alginic acid, and lignin sulfonic acid having a sulfonic acid group can also be mentioned as preferable ones.

Furthermore, a copolymer of a monomer corresponding to the above-mentioned polymer electrolyte and a vinyl monomer having copolymerizability with the monomer can also be used as the polymer electrolyte. . As the copolymerization method in that case, a method such as random copolymerization, block copolymerization, alternating polymerization, or graft polymerization can be applied. The number of acidic groups present in the above-mentioned polymer electrolyte may be only one, or different types may be simultaneously contained. Further, the number of acidic groups may be one or plural.

The polymer electrolyte is used in the form of fine particles. In that case, the average particle size is preferably 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 gaps between the respective components such as the main raw material, the reinforcing material and the admixture cannot be sufficiently reached, and as a result, the bonding force between the respective components is increased. Is not high enough,
Also, the shape retention of the extruded product tends to be low.

In order to obtain such fine particles of the polymer electrolyte, it is preferable to apply the emulsion polymerization method. The form of emulsification at that time may be either a water-in-oil type (W / O type) or an oil-in-water type (O / W type). Examples of the emulsifier used at this time include anionic surfactants such as higher fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonate salts, alkyl phosphate ester salts, polyoxyethylene alkyl sulfate ester salts, and polyoxyethylene. Nonionic surfactants such as alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene fatty acid esters can be mentioned as suitable ones. 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 synthesized polyelectrolyte, 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 emulsion stability is deteriorated. The weight average molecular weight is preferably set in the range of 500,000 to 2,000,000. The polymer electrolyte may partially contain a crosslinked structure.

The amount of the polymer electrolyte added is preferably 0.05 to 2 parts by weight with respect to 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, sufficient alkali thickening will not be exhibited, and it will be difficult to achieve good shape retention and surface smoothness of the extrusion-molded product. Conversely, if it is too large, molding during extrusion molding will be difficult. This is because the pressure increases and stable extrusion molding becomes difficult.

The above-mentioned polyelectrolyte changes its dissolution behavior in water in response to a change in pH. That is, in the acidic region, the polymer electrolyte is insoluble or partially swelled in water, so that the emulsion formed is cloudy. Then, in the alkaline region, the acidic groups in the molecule are neutralized to form a salt, which makes the emulsion substantially water-soluble, so that the emulsion formed becomes transparent and at the same time thickens.

When this emulsion is added to an alkaline hydraulic composition such as cement for extrusion molding, it is preferable that the emulsion exhibits a thickening effect. That is, it is preferable that the polymer electrolyte contained in the emulsion has high solubility in cement alkali. In the present invention, the above-mentioned function of the emulsion used is defined by the alkali solubility (χ) defined by the formula (1).

As is clear from the equation (1), the higher the solubility of the polyelectrolyte contained in the ermajon in the accuracy region, the closer the χ value of the emulsion is to 100%, and in the alkaline region. The χ value of the emulsion containing the insoluble polyelectrolyte becomes 0. That is, the magnitude of the χ value indicates whether or not the contained polymer electrolyte is soluble in alkali, that is, whether or not the viscosity of the emulsion is increased.

In the emulsion used in the present invention, the above χ
The value is set to 40% or more. It is preferably set to 50% or more, more preferably 60% or more. The χ value is defined to be 40% or more for the following reason. That is, first, the emulsion added at the time of extrusion molding of the hydraulic composition is brought into contact with an alkali to be dissolved due to salt formation in the acidic group of the polymer electrolyte, and the viscosity increase is exhibited in the process.

In this case, if the progress of thickening is slower than the time required for kneading and extruding each component, the effect of imparting shape retention to the extruded product is diminished. . On the other hand, when the thickening of the emulsion is completed immediately after kneading, that is, when the progress of the thickening is too fast, the emulsion, that is, the polymer electrolyte is less likely to permeate between the components of the hydraulic composition. As a result, it becomes difficult to obtain an extruded product having excellent shape retention and surface smoothness.

Therefore, the emulsion to be used is the way of increasing the viscosity such that the emulsion thickening is completed within the time from the contact of the emulsion with the alkali during the kneading of the respective components to the completion of the extrusion molding. It is preferable. Such a way of increasing the viscosity can be realized with an emulsion having a χ value of 40% or more. In the formula (1), D ₁₀ is usually measured by adjusting the pH to 10 using an aqueous NaOH solution. In addition, when measuring D ₁₀ and D ₆ , in any case, in order to cancel the influence of the viscosity increase, defoaming, and the like on the measured values, the pH is adjusted and then left standing for 24 hours.

As the emulsion to be used, it is preferable that the viscosity after thickening with alkali is 3000 cps (25 ° C.) or more in the case of an emulsion having a polymer electrolyte concentration of 5% by weight. Even if an emulsion having a viscosity lower than the above value is used, the extrusion moldability is poor,
In addition, the binding force between the components does not become sufficiently high.

It is preferable that the viscosity after thickening is 5000 cps (25 ° C.), especially 10,000 cps (25 ° C.). 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 the above mixture 1
It is usually set to 20 to 30 parts by weight with respect to 00 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. The hydraulic composition thus prepared,
Next, for example, extrusion molding is performed by 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. As the curing method, depending on the type of the extruded body, natural curing, steam curing,
Autoclave curing or a method in which they are appropriately combined can be adopted.

[0032]

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
Parts by weight, and Metroses 90SH3000 (trade name,
1 part by weight of hydroxypropylmethylcellulose powder manufactured by Shin-Etsu Chemical Co., Ltd. was thoroughly mixed with an Erich mixer (Model RV-02 manufactured by Nippon Erich Co., Ltd.).

Methacrylic acid unit 3 was added to the obtained mixed powder.
An O / W type emulsion containing fine particles (particle size, about 2 μm) of a polymer electrolyte (weight average molecular weight, about 800,000) consisting of 0 mol% and methacrylic acid unit 70 mol% was used as the main raw material in an amount of 0.2. 28 parts by weight of the dispersed water was added to the main raw material, and the whole was sufficiently kneaded with a kneader.
The χ value of this emulsion is 62%.

The obtained kneaded product was extruded by a vacuum extruder to obtain an extruded product in the shape of a square rod having a side of 15 mm. This extruded product was cut into a sample having a length of 500 mm, used as a sample, and allowed to stand 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.

After the extruded body was naturally cured for a whole day and night, 7
It was pre-cured for 4 hours in steam at 0 ° C., then put in an autoclave and cured for 5.5 hours in steam at 180 ° C. The bulk density of the molded product after curing is 1.90 g / c
m ³ , bending strength under air-dry condition (span length, 100m
m) and Charpy impact value are 385 kg / cm ² , 3.
It was 1 kg-cm / cm ² .

Example 2 The emulsion used was fine particles of itaconic acid monoethyl ester (weight average molecular weight, about 600,000) (particle size, about 3).
An extruded body was produced in the same manner as in Example 1 except that the emulsion contained the (μm) and had a χ value of 57%. The amount of deflection of the obtained molded product was 1.7 mm, no cracks were observed on the surface, and the surface smoothness was good.

The molded body was cured in the same manner as in Example 1. The bulk density of the molded product after curing is 1.89 g / cm ³ , and the bending strength (span length, 100 mm) and Charpy impact value under air-dry condition are 370 kg / cm ² and 3.0 kg-cm, respectively.
It was / cm ² . Comparative Example The emulsion used was a fine particle (particle size, about 1.5 μm) of a polymer electrolyte (weight average molecular weight of about 1 million) consisting of 1 mol% of acrylic acid unit and 99 mol% of ethyl acrylate unit.
An extruded body was produced in the same manner as in Example 1 except that the emulsion contained m) and had a χ value of 5%.

The amount of deflection of the obtained molded product was 4.1 mm. Also, many cracks were observed on the surface, and the surface smoothness was poor. The molded body was cured in the same manner as in Example 1. The bulk density of the molded product after curing is 1.90 g / c
m ³ , bending strength under air-dry condition (span length, 100m
m) and Charpy impact value are 310 kg / cm ² , 2.
It was 3 kg-cm / cm ² .

[0039]

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,
This is an effect brought about by adding an emulsion containing fine particles of a polymer electrolyte and having an alkali solubility (χ:%) defined by the formula (1) of 40% to a hydraulic composition to be extruded. .

That is, since the emulsion containing this polyelectrolyte has a low viscosity, it penetrates into the gaps between the components of the hydraulic composition, where it is thickened by an alkali to enhance the binding force between the components, Since the lubricity is improved and smooth extrusion molding is possible, the shape retention and surface smoothness of the extruded product and the mechanical strength are improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // (C04B 28/02 24:26 F 24:38 D 14:04 Z 16:02 Z 16: 06 G 14:46) 103: 44 111: 12

Claims (1)

[Claims] 1. An extrusion method of a hydraulic composition containing an asbestos-free reinforcing material, wherein the hydraulic composition is an emulsion of fine particles of a polyelectrolyte having the following formula: χ (%) = 100 × (1−√ (D ₁₀ / D ₆ )) (In the formula, D ₁₀ and D ₆ represent the absorbance of the emulsion at 25 ° C. adjusted to pH 10 and pH 6, respectively. However, the absorbance is a value measured after 24 hours of pH adjustment), and an emulsion having an alkali solubility of 40% or more, which is represented by (2), is added to the extruded product of the hydraulic composition. Production method.