JPH0796509A - Production of extrusion molded object from hoydraulic composition - Google Patents

Abstract

PURPOSE:To provide an extrusion molded object excellent in shape retention and surface smoothness and having high strength and high toughness from a hydraulic compsn. containing an asbestos-free reinforcing material. CONSTITUTION:When a hydraulic compsn. containing an asbestos-free reinforcing material is subjected to extrusion molding, an aq. emulsion (1) containing fine particles of a copolymer consisting of a repeating unit having at least one acidic group as a side group and a repeating unit having at least one group wherein an acidic group is partially substituted with an oleophilic group as a side group and an aq. NaOH soln. (2) satisfying the relation of etaA/etaO>=100 between the viscosity etaA of a soln. adjusted to pH 9 (concn. of copolymer; 5wt.%, liquid temp.; 25 deg.C and the viscosity etaO of a soln. in a non-contact state with alkali (concn. of copolymer, 5wt.%, liquid temp.; 25 deg.C are added to the hydraulic compsn.

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 viscosity of the emulsion being used remarkably increases and the stability of the emulsion deteriorates, causing a problem that extrusion molding becomes difficult.

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 and poor water retention,
This causes a problem such as a high molding pressure during extrusion molding of a hydraulic composition such as a cement composition.

[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 And the following aqueous emulsion: 1) a repeating unit having at least one acidic group as a side group, and a repeating unit having at least one group in which a part of the acidic group is substituted with a lipophilic group as a side group. 2) A liquid adjusted to pH 9 with an aqueous NaOH solution (however,
The concentration of the copolymer is 5% by weight, the viscosity of the liquid temperature is 25 ° C., is η _A , and the liquid not in contact with the alkali (however,
5 wt% concentration of the copolymer, when the viscosity of the liquid temperature 25 ° C.) and eta _0, Between eta _A and η _0, η _A / η
There is provided a method for producing an extrusion-molded body of a hydraulic composition, characterized in that the relationship of ₀ ≧ 100 is added.

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, it is preferably contained in an amount of 1 to 30 parts by weight, and depending on the purpose, 5 to 20 parts by weight, based on 100 parts by weight of the main raw material. 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; Sepiolite, bentonite, which improves water retention during extrusion
Inorganic minerals such as zeolite, super absorbent polymers such as acrylic polymers and starches, fillers such as calcium carbonate and kaolin; perlite, shirasu balloons, glass balloons, synthetic resins that reduce the weight of extruded products. Foam beads;

In the method of the present invention, an aqueous emulsion described below is further added as an essential component when the above 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 aqueous emulsion used in the method of the present invention is characterized by the following properties.

First, this aqueous emulsion contains fine particles of a copolymer described later. That is, the copolymer comprises a repeating unit having at least one acidic group as a side group (hereinafter referred to as repeating unit A) and at least one group in which a part of the acidic group is substituted with a lipophilic group. It is essential to be composed of a repeating unit having a side group (hereinafter referred to as repeating unit B).

This is because the homopolymer consisting only of the repeating unit A is unstable as an aqueous emulsion, and when it comes into contact with an alkali, the viscosity thereof increases sharply and becomes difficult to handle. Further, in the case of a homopolymer consisting only of the repeating unit B, no thickening effect is observed even when contacted with alkali, and the effect of increasing the water retention property to the hydraulic composition and the binding force between the respective components is not exhibited. There is.

Here, the acidic group is a group having a property of releasing H ⁺ by dissociating when contacted with water. Specifically, for example, a carboxyl group, a sulfonic acid group, a phosphoric acid group (-PO ₃ H _2), phosphorous acid group (-PO ₂ H ₂₎ and the like. Such an acidic group exists as a side group in the main chain of the repeating unit A described above. In that case,
Only one kind of acidic group may be contained, or different kinds of acidic groups may be contained at the same time. Further, the number of acidic groups may be one or plural.

Next, a group substituted with a lipophilic group means that the hydrogen atom or hydroxyl group of the above-mentioned acidic group is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group or a butyl group, or a fatty group. A group substituted with a hydrocarbon group such as a group cyclic group or an aromatic group. For example,
When the acidic group is a carboxyl group, the above hydrocarbon group is introduced into the main chain of the repeating unit B via an ester group or a carbonyl group.

The copolymerization ratio of the repeating unit A and the repeating unit B in this copolymer varies depending on the kind and combination of the monomers used, but it should be stable and stable as an aqueous emulsion. It is appropriately selected so as to exert an appropriate thickening by the contact of. For example, when synthesizing a copolymer using acrylic acid and acrylic ester as monomers, the copolymerization ratio of the repeating unit A made of acrylic acid may be 5 to 80% by weight. Preferably, it may be 20 to 60% by weight. If the copolymerization ratio of the repeating unit A is too small, the thickening effect when the copolymer comes into contact with alkali becomes poor, and if it is too large, it becomes unstable as an aqueous emulsion,
Further, it is difficult to control the viscosity.

The copolymer 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 gap between the respective components such as the main raw material, the reinforcing material and the admixture cannot be sufficiently reached,
As a result, the bond strength between the components is not sufficiently high, and the shape retention of the extruded product tends to be low.

In order to obtain fine particles of such a copolymer, it is preferable to apply an emulsion polymerization method. Examples of the emulsifier used at this time include higher fatty acid salts,
Anionic surfactants such as alkyl sulfate ester salts, alkyl benzene sulfonate salts, alkyl phosphate ester salts, polyoxyethylene alkyl sulfate ester salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol esters, polyoxyethylene fatty acid esters Nonionic surfactants such as the above can be mentioned as preferable ones. As the polymerization initiator, in addition to known peroxides, usual radical polymerization initiators such as redox catalysts can be used.

Regarding the molecular weight of the synthesized copolymer, 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 copolymer may partially include a crosslinked structure.

The amount of the copolymer added 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, the main raw material 10
It is 0.1 to 0.5 parts by weight relative to 0 parts by weight. 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. This copolymer is insoluble or sparingly soluble in water and forms an aqueous emulsion. Then, when this emulsion comes into contact with an alkali such as cement, the acidic group of the repeating unit A in the copolymer is neutralized to form a salt and becomes water-soluble, and at that time, the viscosity of the emulsion increases to increase the viscosity. Stick. Usually, a large thickening effect is exhibited in the range of pH 9 to 13.

For this reason, the aqueous emulsion used in the present invention is required to have the following viscosity characteristics. That is, the concentration of the copolymer was adjusted to 5% by weight, the liquid temperature was controlled to 25 ° C., and
The viscosity of an aqueous emulsion that is not in contact with alkali is η _{0 as} measured with a B-type viscometer, and the concentration of the copolymer is adjusted to 5% by weight and the liquid temperature is 25.
If the viscosity of the aqueous emulsion is η _A when the pH is controlled to be 0 ° C. and the pH is adjusted to 9 with an aqueous NaOH solution, it is necessary to satisfy η _A / η ₀ ≧ 100. An aqueous emulsion having a viscosity characteristic such that η _A / η ₀ <100 has a small thickening effect and cannot sufficiently enhance the binding force between the respective components of the hydraulic composition, and therefore the extruded product has Shape retention becomes insufficient. η _A / η ₀ ≧
When it is 100, the shape retention of the extruded product also satisfies a practical level, and the thickened emulsion exhibits spinnability and can enhance the binding force between the respective components.

The viscosity characteristic of the emulsion is η _A / η ₀ ≧
200 is preferable, and in particular, η _A / η ₀ ≧ 3
It is preferably 00. In the method of the present invention, first, a main raw material composed of a calcareous raw material and a siliceous raw material,
A reinforcing material in place of asbestos, various admixtures described above, and optionally a water-soluble cellulose derivative powder,
For example, the mixture is mixed with an Erich mixer to form a mixture, to which an appropriate amount of water is added and the whole is stirred. The amount of water added is usually 20 to 30 with respect to 100 parts by weight of the above mixture.
Set to parts by weight.

In this case, the above-mentioned aqueous emulsion is
It is preferable to add the predetermined amount in a state of being dispersed in the above-mentioned water. 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. As the curing method, natural curing, steam curing, autoclave curing, or a combination thereof may be adopted depending on the type of the extruded body.

[0028]

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, and an average 10 parts by weight of talc having a particle size of 5 μm,
1.8 parts by weight of pulp, polypropylene fiber with a fiber length of 6 mm
5 parts by weight and 1 part by weight of Metroze 90SH30000 (trade name, hydroxypropylmethylcellulose powder manufactured by Shin-Etsu Chemical Co., Ltd.) were sufficiently mixed with an Erich mixer (Model RV-02, manufactured by Nippon Erich Co., Ltd.).

A copolymer having a copolymerization ratio of repeating unit A of acrylic acid of 50% by weight and a repeating unit B of ethyl allylate of 50% by weight in the obtained mixed powder (weight average 28 parts by weight of water, in which 0.2 parts by weight of an aqueous emulsion containing fine particles (particle size, about 1 μm) having a molecular weight of about 900,000 are dispersed, is added to the main raw material. Was sufficiently kneaded with a kneader.

Η _A / η ₀ of the above aqueous emulsion
Was 500. The obtained kneaded product was extrusion-molded by a vacuum extruder to obtain a rectangular rod-shaped extrusion molded product having a side of 1.5 mm. The extruded product was cut into a sample having a length of 500 mm, and the sample was 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 is 1.
It was 5 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 390 kg / cm ² , 3.
It was 2 kg-cm / cm ² .

Example 2 A copolymer in which the aqueous emulsion used had a copolymerization ratio of repeating unit A of styrene sulfonic acid of 60% by weight and a repeating unit B of methyl methacrylate of 40% by weight. Example 1 except that it was an aqueous emulsion containing (weight average molecular weight, about 1.1 million) fine particles (particle size, about 2 μm) and η _A / η ₀ of 150.
An extruded body was manufactured in the same manner as in.

The amount of flexure of the obtained molded product was 0.8 mm, and 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 molded product after curing has a bulk density of 1.89 g / cm ³ , flexural strength (span length, 100 mm) and Charpy impact value under air-drying conditions of 380 kg / cm ² and 3.1 kg-cm /, respectively.
It was cm ² .

COMPARATIVE EXAMPLE A copolymer in which the aqueous emulsion used had a copolymerization ratio of repeating unit A of acrylic acid of 3% by weight and a repeating unit B of ethyl allylate of 97% by weight. Fine particles with an average molecular weight of about 1 million (particle size, about
An extrusion molded body was produced in the same manner as in Example 1 except that the aqueous emulsion contained 1.5 μm) and had an η _A / η ₀ of 25.

The amount of deflection of the obtained molded product was 3.0 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 330 kg / cm ² , 2.
It was 5 kg-cm / cm ² .

[0036]

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 contains fine particles of the above-mentioned copolymer of the repeating unit A and the repeating unit B, and η _A / η
_This is an effect brought about by adding an aqueous emulsion in which ₀ becomes a value of 100 or more.

That is, since the emulsion of this copolymer 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 and to form a slip. To improve smoothness and enable smooth extrusion molding.
Furthermore, the mechanical strength is improved.

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Claims (2)

[Claims] 1. When extrusion molding a hydraulic composition containing an asbestos reinforcing material, the hydraulic composition contains the following aqueous emulsion: 1) at least one acidic group as a side group. Containing fine particles of a copolymer comprising a repeating unit having a repeating unit and a repeating unit having at least one group in which a part of the acidic group is substituted with a lipophilic group as a side group; 2) pH 9 with an aqueous NaOH solution Prepared liquid (however,
The concentration of the copolymer is 5% by weight, the viscosity of the liquid temperature is 25 ° C., is η _A , and the liquid not in contact with the alkali (however,
5 wt% concentration of the copolymer, when the viscosity of the liquid temperature 25 ° C.) and eta _0, Between eta _A and η _0, η _A / η
Satisfying the relation of ₀ ≧ 100; a method for producing an extrusion-molded body of a hydraulic composition, characterized by adding. 2. The extrusion-molded article of the hydraulic composition according to claim 1, wherein the acidic group is at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, a phosphoric acid group and a phosphorous acid group. Method.