JPH0755850B2 - Admixture for cement extrusion products - Google Patents

Description

TECHNICAL FIELD The present invention relates to an admixture for cement extrusion molding. That is, the present invention relates to an admixture for cement extruded products produced by an extrusion molding method using cementitious materials and fibrous materials as main raw materials.

[Prior Art] A conventional method for extrusion-molding a water-kneaded product containing a cementitious material as a main component is, for example, when a water-kneaded product of asbestos or cement is extruded, a problem particularly occurs in die Due to the pressure, the water-kneaded material has poor water-holding properties, causing a dehydration phenomenon and making extrusion impossible.

Conventionally, in order to prevent this dehydration phenomenon, hydro-modifying agents such as cellulose derivatives, polyvinyl alcohol, polyethylene oxide and polyacrylamide are known.
(For example, Japanese Examined Patent Publication No. 43-7134) [Problems to be Solved by the Invention] However, in such a conventional extrusion molding process, asbestos use was indispensable like the conventional slate. Due to the danger of harm to health, its use is banned in European countries, including the United States, and is being regulated in Japan. Therefore, a so-called non-asbestos system, which does not use asbestos, is currently being studied in the extrusion molded article.

In such a non-asbestos formulation, the admixture for cement extrusion molded article described above has a markedly reduced function, the extrusion pressure increases, and the surface smoothness of the extrusion molded article becomes poor, resulting in extremely poor extrusion workability. It has drawbacks.

[Means for Solving the Problems] The inventors of the present invention have reached the present invention as a result of earnest research to solve the above problems. That is, the present invention provides at least one of an alkyl cellulose ether having a particle size of 100 μ or less and 50 wt% or more of which is 50 μ or less, and a hydroxyalkyl alkyl cellulose ether.
The present invention provides an admixture for a cement extrusion molded article, which comprises one or more kinds.

Examples of the alkyl cellulose ether and hydroxyalkyl alkyl cellulose ether used in the present invention include, for example, methyl cellulose (MC), methyl hydroxyethyl cellulose (MHEC), methyl hydroxypropyl cellulose (MHPC), and the like. The use of cellulose ethers such as (HPEC) and hydroxyethylethyl cellulose (HEEC) does not hinder the effect of the present invention. Among them, methyl cellulose, methyl hydroxyethyl cellulose and, and the particle size of methyl hydroxypropyl cellulose is 100μ or less, 50 wt% or more 50μ or less, more preferably its particle size is 76μ,
50% by weight or more is 45 μ or less.

The methyl cellulose, methyl hydroxypropyl cellulose, and methyl hydroxyethyl cellulose used in the present invention preferably have a viscosity in a 2% aqueous solution,
300cp-150,000cp, more preferably 3,000cp-100,000cp
It is in the range of.

Further, as the degree of substitution, the degree of methoxy substitution (DS) 1.0 to 2.2 of alkyl cellulose, and the degree of methoxy substitution (DS) 1.0 of hydroxyalkyl alkyl cellulose
~ 2.5, degree of hydroxyalkyl molar substitution (MS) 0.05 ~ 2.5
Those having the following are more preferably used.

The degree of polymerization of these hydroxyalkyl alkyl cellulose ethers is more preferably 200 or more and 1,500 or less.

As the cementitious material used in the present invention, in addition to ordinary Portland cement, almost all cementitious materials such as blast furnace cement and fly ash cement can be used.

Further, asbestos for reinforcement, inorganic materials such as glass fibers, nylon fibers, carbon fibers, aramid fibers, even if added organic fibers such as polypropylene, does not impair the effect of the present invention at all, other water-soluble polymer The compounds can also be used in combination.

The use ratio of the alkyl cellulose ether to be added and the hydroxyalkyl alkyl cellulose ether to the cementitious material is variously selected according to the selected cementitious material, the shape of the extruder die, etc., and thus is particularly limited in the present invention. Not the thing, but usually the former 0.1
What is contained in the latter 100 parts by weight is preferably used.

The amount of water is usually 15 to 80 parts by weight, preferably 15 to 40 parts.
Parts by weight are used.

An example of the method of using the admixture of the present invention is as follows. That is, after cement-based materials, fibrous materials, aggregates, and the admixture of the present invention are dry blended with a kneader type mixer, etc., water is added, and a screw type extruder is used.
The water-kneaded product is extruded into a desired shape through a plunger type extrusion molding machine and the like and a die attached to the tip thereof.

The extruded extruded product is cut into a desired length with a cutter or the like, and then cured at room temperature by steam curing or autoclave curing to obtain a post-cured product.

In the present invention, each compounding material, and the amount thereof is appropriately compounded, the particle size is 100μ or less, 50 wt% or more of the alkyl cellulose ether is 50μ or less, and hydroxyalkyl alkyl cellulose The main point is to blend at least one kind of ether.

By finely pulverizing the particle size, dispersion and mixing are good,
Workability is improved by entering the gap between cement, aggregate, etc., and exerting a water retaining effect especially in a region where the water / cement ratio is low.

Further, in this case, if a salt of a naphthalene sulfonic acid formalin condensate, a salt of an alkylnaphthalene sulfonic acid formalin condensate, a salt of a melamine sulfonic acid formalin condensate, etc. is used in combination, the effect is further promoted.

On the other hand, the fineness of the above-mentioned methyl cellulose and hydroxyalkylalkyl cellulose ether is more preferably a fine powder, however, from the viewpoint of equipment, cost, etc., there is naturally a limit and practically there is a limit. It was concluded that it is preferable that the total amount of fineness is 100μ or less and 50% or less of 50% or less.

On the other hand, regarding the admixture of the present invention, the DS and MS thereof were not affected by the particle size, and the molding speed and the surface smoothness of the molded article were improved by using the DS and MS products in the above range.

The present invention will be specifically described below with reference to examples. [%,
Parts are by weight] Example 1 As shown in Table 1, a hydroxyalkylalkyl cellulose ether A having a normal particle size (DS) = 1.65. Low tap to have different particle size distributions A, A, A, 3
Sorted into types. No difference due to sieving was observed in these substitution degrees.

These were tested as admixtures for cement extrusions.

[Test] Portland cement 100 (parts by weight) Quartz sand 50 (parts by weight) Rock wool 10 (parts by weight) Carbon fiber 1 (parts by weight) Cellulose ether 1.5 (parts by weight) After dry blending the above components, water was added, After kneading with a mortar mixer, a kneaded material (mortar) was prepared, and the kneaded material was measured for its molding speed with an extruder. Furthermore, the smoothness of the surface of the extruded product was visually determined.

Surface smoothness: [◎: Excellent ◯: Good Δ: Acceptable ×: Not acceptable] After extrusion molding, the extruded product was cured in water at 20 ° C to measure the bending strength. (According to ASTM-293-68.) As shown in Table 3, hydroxyalkylalkyl cellulose ether samples A, A, A having a total powder particle size of 74 μm or less and 50% or more of 46 μm or less.
Is A of the mother. Compared with, the extrusion speed is higher. The surface smoothness and strength were also good.

Extrusion speed (cm / min) and flexural strength (4-week strength kg / cm ² )
Is mother A. The value at 100 was compared as 100.

Example 2 Table 2 shows the matrix A of Table 1. 100 μ or more of the screened hydroxyalkyl alkyl cellulose ether was used as sample A, and A was re-ground to obtain a total particle size of 74 μ or less, and 46 μ or less so as to be 50% or more.
Got

This was tested as in Example 1. As a result, as is clear from the results shown in Table 4, Sample A is the mother A. Compared with, the extrusion rate was faster, and the surface smoothness and strength were also good, but A was the base A. Was inferior.

Example 3 Different B of each particle size, each viscosity and each type shown in Table 1. , C. , D. Each of the cellulose ethers of No. 1 and No. 2 was subjected to sieving with a low tap until the total particle size was 74 μ or less, and 46 μ or less became 50% or more.
, C, and D.

These were tested as in Example 1. The result is the fifth
Shown in the table.

As is clear from Table 5, even if the substitution degree, viscosity, and type were different, the finely pulverized B, C, and D had a faster extrusion molding rate than the respective bases, good surface smoothness, and bending strength. A remarkable improvement in the performance of the admixture for cement extruded products, which is that the improvement is obtained, was recognized.

[Advantages of the Invention] The admixture of the present invention has the above characteristics as an admixture for cement extrusion molded articles, as compared with conventional additives.

The extrusion speed of the extruded product is increased, and the production amount of the extruded product per unit time can be improved.

The water retention is further exhibited, and the surface smoothness of the extruded product is improved.

Dispersion and mixing are improved, and bending strength is increased.

Extrusion in the non-asbestos formulation eliminates the dehydration phenomenon in the extruder.

The extruded product using the admixture of the present invention having the above characteristics is useful as a building outer wall, a partition wall, a floor panel, an outer wall material for general houses, and the like.

Claims (5)

[Claims] 1. A particle size of 100 μ or less, 50% by weight of which
An admixture for a cement extrusion molded article, which comprises at least one kind of an alkyl cellulose ether having a content of 50 μm or less and a hydroxyalkyl alkyl cellulose ether. 2. The admixture for a cement extrusion molded article according to claim 1, which is an alkyl cellulose ether having a methoxy substitution degree (DS) of 1.0 to 2.2. 3. An admixture for a cement extruded product according to claim 1, which is a hydroxyalkylalkyl cellulose ether having a methoxy substitution degree (DS) of 1.0 to 2.5 and a hydroxyalkyl molar substitution degree (MS) of 0.05 to 2.5. . 4. The admixture for a cement extrusion molded article according to claim 1, which is an alkyl cellulose ether having a polymerization degree of 200 or more and 1,500 or less, or a hydroxyalkyl alkyl cellulose ether. 5. The admixture for a cement extrusion molded article according to claim 1, which is an alkyl cellulose ether having a bulk specific gravity of 0.150 to 0.550 or a hydroxyalkyl alkyl cellulose ether.