JPH05124845A - Hydraulic composition - Google Patents

Abstract

PURPOSE:To obtain a molded body having further improved bending strength and dimensional stability by allowing mica powder to adhere more tightly to a hydraulic material in a hydraulic compsn. CONSTITUTION:This hydraulic compsn. contains mica powder surface-coated with a polyvinyl alcohol-based material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic composition having high strength, which is used as a material for construction and civil engineering.

[0002]

2. Description of the Related Art A hydraulic composition such as cement, which is used as a material for construction and civil engineering, is reinforced with a fibrous material so as to give necessary strength, and asbestos fibers are particularly used in a large amount. Often used in the form of. However,
It is not preferable in terms of price and hygiene and safety because there are legal regulations such as the boiling of prices due to the exhaustion of asbestos fiber resources and the regulation of handling as a hazardous substance. Therefore, as alternatives to asbestos fibers, pitch-based, PAN-based carbon fibers, vinylon fibers,
Acrylic fiber, polypropylene fiber, glass fiber, pulp, etc. are used.

[0003]

However, although these methods can provide a certain level of performance in terms of high strength, they undergo a large dimensional change in dry and wet conditions, and cracks or breakage due to expansion and contraction of the cement plate, and deformation of the accompanying structural material. However, it has the drawbacks of being easily damaged and being inferior in flame retardancy.

As a method of improving these drawbacks, a method of adding mica powder to a hydraulic material has been proposed (Japanese Patent Publication No. 61-29900 and Japanese Patent Publication No. 61-29901). Also, a method of adding polyvinyl alcohol to a hydraulic material has been proposed. (JP-A-3-97644
Publication). However, at present, no alternative material has been found that completely replaces asbestos in terms of processability, performance, and price.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention have diligently studied these improvements from various viewpoints, and by using a mica powder whose surface is coated with a specific substance as an alternative to asbestos fibers, The present invention has been completed by finding that a hydraulic composition excellent in strength, dry and wet dimensional stability (crack resistance), and flame retardancy can be obtained and is economically advantageous.

[0006]

The present invention is a hydraulic composition containing a mica powder whose surface is coated with a polyvinyl alcohol-based substance.

Examples of the hydraulic material of the present invention include early-strength and ultra-early-strength Portland cement, mixed cement obtained by mixing blast furnace slag, fly ash and silica with these, gypsum, granulated slag, magnesium carbonate and calcium silicate. An inorganic substance having hydraulic properties such as is used.

The polyvinyl alcohol-based substance used in the present invention includes polyvinyl alcohol (hereinafter abbreviated as PVA), silyl group-modified PVA, and carboxyl group-modified P.
VA is used. The degree of polymerization and the degree of saponification of these PVA-based substances are appropriately selected according to the purpose and are not particularly limited, but the degree of polymerization is preferably 300 or more, particularly preferably 500 or more in terms of the ease of coating the mica powder. Degree of conversion is 70 mol%
Above, especially 80 mol% or more is preferable. Further, the modification amount of the silyl group-modified PVA or the carboxyl group-modified PVA is appropriately selected according to the purpose and is not particularly limited, and the effect is exhibited even with a relatively small modification amount. In the present invention, the modification amount is 0.
The range of 1 to 10 mol% is preferable in terms of effects. P
As for the method of using the VA-based substance, since it coats the surface of the mica powder, it is effective to use it as an aqueous solution, and its concentration is preferably 0.1 to 30% by weight in terms of operation.

The above silyl group-modified PVA can be produced, for example, by the method described in JP-B-64-2684. That is, as the method for producing a silyl group-modified PVA, (1) a method of introducing a silyl group into PVA by post-modification using a silylating agent, and (2) silylation of a modified polyvinyl ester having a hydroxyl group with a silylating agent. Group is introduced, and the resulting silyl group-modified polyvinyl ester is saponified, (3) a copolymer of a vinyl ester and a silyl group-containing olefinically unsaturated monomer is saponified, and (4) a silyl group. A method of saponifying a terminal silyl group-modified polyvinyl ester obtained by polymerizing a vinyl ester in the presence of a mercaptan having

Further, the above-mentioned carboxyl group-modified PVA
Can be obtained by alkali-saponifying a copolymer of vinyl acetate and an ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid and itaconic acid.

The mica powder of the present invention can be used in a range from a small particle size to a large particle size, but a weight average particle size of 10 μm or more, particularly 20 μm or more is preferable in terms of reinforcing effect, An average aspect ratio of 10 or more, particularly 15 or more is preferable. Further, the chemical composition, crystal form, place of origin, pulverization method, etc. are not limited at all, and are appropriately selected from, for example, muscovite, biotite, phlogopite, soda mica and synthetic mica.

The weight average particle diameter (l) of the mica powder used in the present invention is classified by a sieve, and the integrated weight of the mica powder remaining on each sieve is represented by the Rosin-Ram.
It is a value obtained by l = √2l ↓ 50, where l ↓ 50 is the opening of the sieve through which 50 wt% of the total weight of the mica powder passes, which is plotted in the mler diagram. The weight average aspect ratio (α) of the mica powder is a value calculated by the following formula, where the weight average particle diameter is 1 and the weight average thickness is d. α = 1 / d The thickness d is a value measured by the water surface single particle film method, that is, the method described in Nishino, Arakawa, Materials, Vol. 27, 298, p.

The mica powder of the present invention may be coated as it is with a PVA type substance, but in order to further enhance the reinforcing effect, the surface thereof is a silane compound such as vinyl-tris (β).
-Methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and the like are preferred.

In the present invention, PVA is formed on the surface of the mica powder.
Examples of the method for coating the base material include (1) a method in which the PVA-based material is used as an aqueous solution, and the aqueous solution is sprayed on mica powder, and (2) a method in which the mica powder is immersed in the aqueous solution and water is removed by filtration or the like. Etc.

The content of the mica powder can be appropriately selected depending on the required characteristics, but in the point of reinforcing effect and dimensional stability, it is in the range of 2 to 30% by weight, particularly 2 to 20% by weight based on the total solid content. Preferably. When the content is less than 2% by weight, the reinforcing effect and the reduction in dimensional change due to dry and wet conditions are not sufficient, and when the content exceeds 30% by weight, the strength is deteriorated, which is not preferable.

The amount of the PVA-based substance used to coat the surface of the mica powder varies depending on the type and composition of the hydraulic substance and is not particularly limited, but it is 3 times the weight average thickness of the mica powder.
A coating amount of not more than twice, particularly not more than twice, is preferable.
If the coating amount exceeds 3 times, the dimensional change due to dry and wet is not sufficiently reduced, which is not preferable.

The hydraulic composition of the present invention is usually used as a reinforcing material for cement or the like in order to impart higher performance product strength, for example, vinylon type, acrylic type,
Olefins, carbon, aramid fibers, pulps such as synthetic pulp, wood pulp, and beating pulp of wood, inorganic fillers such as glass balloons, shirasu balloons, powdered silica, fly ash, sand, gravel, lightweight aggregates. It may contain a filler such as, and may contain bubbles. Further, the PVA-based substance may contain boric acid, borax, etc., which are usually used as a thickener.

When the hydraulic composition of the present invention is used as a building material, it is effective to carry out curing such as natural curing, steam curing and autoclave curing in order to improve dimensional stability.

The hydraulic composition of the present invention is used as a molding material for plate-like materials used for roofs, outer walls, inner walls, etc., road blocks, revetment blocks, etc.

[0020]

In the present invention, by coating the surface of the mica powder with a PVA-based substance, when the mica powder is added to a hydraulic substance such as cement, the cement particles and the mica powder are more strongly adhered to each other and have high strength. A hydraulic composition of is obtained.
Further, the PVA-based substance may be used in an amount enough to cover the surface of the mica powder, which is economically advantageous.

[0021]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, each physical property in an Example was measured by the following method. (1) Bending strength: Measured according to JIS A 1408 (span distance 5 cm). (2) Dimensional change rate: Measured according to JIS A 5416.

Examples 1 to 3 Mica powder (Clarite mica 60-C, weight average) surface-treated with 0.5% by weight of γ-aminopropyltriethoxysilane (Sanla Ace S-330, manufactured by Chisso Corporation). A particle size of 340 μm, manufactured by Kuraray Co., Ltd., and a 10 wt% aqueous solution of silyl group-modified PVA (R-1130, manufactured by Kuraray Co., Ltd.) were mixed in a Henschel mixer so that the ratios shown in Table 1 were obtained, and then stirred. While drying, mica powder whose surface was coated with silyl group-modified PVA was obtained (coating thickness: 0.25 μm).

60 g of this mica powder and Portland cement (manufactured by Onoda Cement) were mixed at the ratio shown in Table 1.
The operation of dispersing in water at a ratio of (solid content) / l and making a paper with a tappy paper making machine was repeated 5 times to obtain a 5-layer laminate. This laminate was press-molded at a pressure of 75 kg / cm ↑ 2 to produce a molded plate. The molded plate obtained was subjected to primary curing (50 ° C., 10
After 0% humidity, 1 day, secondary curing (25 ℃, 80% humidity,
14 days) to obtain a cured molded article. A test piece was cut out from the obtained cured molded article, and each physical property was measured. The results are shown in Table 1.

Examples 4 to 7 In Example 2, a mica powder surface-treated with γ-aminopropyltriethoxysilane is used (Example 4). Instead of the silyl group-modified PVA, a carboxyl group-modified PVA (KM-) is used. 118, manufactured by Kuraray Co., Ltd. (Example 5), unmodified PVA (PVA-117, molecular weight 175)
0, manufactured by Kuraray Co., Ltd. (Example 6), unmodified PVA (P
A cured molded article was obtained in the same manner except that VA-203, molecular weight 300, manufactured by Kuraray Co., Ltd. (Example 7) was used.
A test piece was cut out from the obtained molded body and each physical property was measured. The results are shown in Table 1.

Examples 8 and 9 In Example 2, the mica powder had a weight average particle size of 30.
μm mica powder (Clarite mica 300W, manufactured by Kuraray Co., Ltd.) (Example 8), mica powder having a weight average particle size of 680 μm (Clarite mica 30-C, manufactured by Kuraray Co., Ltd.)
A cured molded article was obtained in the same manner except that (Example 9) was used. A test piece was cut out from the obtained molded body and each physical property was measured. The results are shown in Table 1.

Comparative Example 1 A cured molded article was obtained in the same manner as in Example 2, except that the silyl group-modified PVA was not used. A test piece was cut out from the obtained molded body and each physical property was measured. The results are shown in Table 1. It can be seen that the bending strength is extremely inferior and the adhesiveness between the cement and the mica powder is low as compared with the molded body obtained in Example 2.

Comparative Example 2 Mica powder (Clarite Mica 60-C, Ltd.) surface-treated with 0.5% by weight of γ-aminopropyltriethoxysilane (Sanla Ace S-330, manufactured by Chisso Corporation).
Kuraray) and Portland cement were mixed in a ratio of 5/95 (weight ratio), and a 10 wt% silyl group-modified PVA (R-1130, Kuraray Co., Ltd.) aqueous solution was mixed with PV.
The A-based substance was mixed so as to be 5% by weight with respect to the mica powder, and then dispersed in water at a ratio of 60 g (solid content) / l,
A cured molded article was obtained in the same manner as in Example 2. The bending strength of the obtained molded product was 190 kg / cm ↑ 2, which was extremely inferior to the molded product obtained in Example 2.

Comparative Example 3 In Comparative Example 2, in order to obtain a molded product having a bending strength equivalent to that of the molded product obtained in Example 2, 10
A 40% amount by weight of a silyl group-modified PVA aqueous solution was necessary.

[0029]

[Table 1]

As is clear from Table 1, the bending strength of the molded product obtained by simply mixing the PVA-based substance with the mica powder and Portland cement is insufficient, and the molding having a certain degree of bending strength is obtained. To obtain the body, a large amount of PVA compound is required, which is economically disadvantageous.

[0031]

By coating the surface of the mica powder with the PVA-based substance, a molded product having improved bending strength can be obtained as compared with the conventional molded product made of the hydraulic substance containing mica powder.
That is, the adhesion between the mica powder and the cement particles becomes stronger. Further, as compared with simply mixing the PVA-based substance, the amount of the PVA-based substance used is small, which is economically advantageous.

Claims (2)

[Claims] 1. A hydraulic composition comprising a mica powder whose surface is coated with a polyvinyl alcohol-based substance. 2. The hydraulic composition according to claim 1, wherein the polyvinyl alcohol-based substance is a silyl group-modified polyvinyl alcohol or a carboxyl group-modified polyvinyl alcohol.