JPS5935855B2 - Asbestos cement composition for extrusion molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an asbestos-cement composition for forming extruded products used as building materials, particularly as interior and exterior materials for buildings.

Conventionally, asbestos cement extrusion molded products are made by mixing a composition of cementitious raw materials, reinforcing asbestos, and a plasticizer with the addition of water to form a paste-like plastic product, which is then processed using a vacuum forming machine, etc. Molded using an extrusion molding machine.

However, extrusion-molded products made from the above-mentioned composition using only asbestos have the drawback of significantly inferior impact strength and toughness.

In order to improve this drawback, various fibers such as alkali-resistant glass, pulp, recycled cellulose, nylon, polyester, vinylon, polypropylene (hereinafter referred to as PP), and polyethylene (hereinafter referred to as PE) are further added to the asbestos cement composition. Attempts are being made to do so.

Among the above-mentioned fibers, compositions containing glass fibers are subject to severe breakage during extrusion molding, and furthermore, when molded products are autoclaved (cured), even alkali-resistant glass fibers are susceptible to chemical alkali attack. , the reinforcing effect is not sufficient.

In addition, fibers such as nylon, polyester, vinylon, etc.
Like glass fiber, it is decomposed by hot alkali, so it has little effect on increasing the strength of molded products.

In addition, cellulose fibers such as pulp are chemically and thermally strong (they do not deteriorate with curing, but the reinforcing effect does not increase unless they are quite long fibers, and for this reason, it is obvious from the manufacturing principle. It is unsuitable as a reinforcing material for extrusion molding because the length of the fibers used is limited.

Also, pp. PE is chemically stable, and PP in particular has a high melting point and does not deteriorate even at relatively high temperatures during curing.

However, since the surface of PP woven fibers is non-ionic, it does not adhere well to the ionic cement matrix, and cement molded products using this fiber tend to have a phenomenon in which the fibers are pulled out when they break. As is clear from this, the reinforcing properties are not sufficient.

In particular, in the case of extrusion molding, there is a limit to the length of the fibers that can be used, and relatively short fibers are used, so in order to create a molded product with the required impact resistance and toughness, a large amount of fibers must be blended. There is a need.

This increases the cost of the molded product and significantly impairs its nonflammability.

In view of the above circumstances, the inventor has conducted extensive research and found that
It has been found that by using hollow synthetic fibers instead of conventional fibers added to a composition mainly consisting of asbestos and cement, reinforcing properties are significantly improved and molded products with excellent impact resistance and toughness can be obtained. .

That is, the gist of the present invention is an asbestos cement composition for extrusion molding, which contains asbestos and calcium silicate hydrate as main components, and contains hollow synthetic fibers therein.

The present invention will be explained in detail below.

The cementitious raw material used in the composition according to the present invention is a calcium silicate hydrate blended with silicic acid raw materials and calcareous raw materials such as Portland cement, slag, fly ash, lime, silica, diatomaceous earth, and ferrosilicon dust.

Further, as asbestos, for example, 5.6 or 7 class chrysotile, amosite asbestos, etc. are used.

In addition, as hollow fibers for reinforcement, fiber diameters of 0.5 to 30
Denier, preferably 1-20 denier, fiber length 2-1
A length of 0m7ft is used.

The amount added is preferably 0.1 to 10% by weight based on the total of asbestos and calcium silicate hydrate.

The reason why the diameter of the hollow fiber is set to 0.5 to 30 deniers is that 0
．． Below 5 deniers, the strength is low because the fibers are thin;
At 0 denier or more, the number of pieces per unit volume is small.

All of these reduce the reinforcing effect of the fibers on the molded body.

The reason why the fiber length is increased by 2 to 10 mm is that if the fiber length is less than 2 mm, there is almost no reinforcing effect, and if the fiber length is 10 mm or more, the moldability will be hindered when extrusion molding is performed.

In addition, the addition amount was 0.1 to 10% by weight.
If the amount is less than 10% by weight, the desired reinforcing properties cannot be obtained, and if it is more than 10% by weight, the non-flammability of the molded article decreases and clumping occurs due to poor mixing of fibers, which impairs moldability.

The reason why hollow fibers are effective is not clear, but it is thought that in cement molded products, the cross-sectional area of the fibers tends to be non-uniform over the entire length of the fibers.

The present invention will be explained in more detail below with reference to Examples.

The results of Example 1.2 and Comparative Example 1.2 are shown in Table 3.

Example 1 A plasticized paste containing the raw materials listed in Table 1 was extruded using an extruder to form a hollow panel with a thickness of 10 mm.

This was cured in an autoclave at 110° C. for 6 hours, left indoors for 10 days, and then its Charpy impact strength was measured.

Comparative Example 1 Charpy impact strength was measured using the same K as in Example 1, except that ordinary solid PP woven fibers of 7 denier x 6 ml were used instead of hollow PP woven fibers.

Example 2 A plasticized paste containing the raw materials listed in Table 2 was mixed with an extruder to form a hollow panel with a thickness of 10 mm.

This was autoclaved at 140° C. for 4 hours, left indoors for 10 days, and then its Charpy impact strength was measured.

Comparative Example 2 Charpy impact strength was measured in the same manner as in Example 2, except that ordinary solid fibers of 7 denier x 6 m@L were used instead of hollow PP woven fibers.

From the above results, it can be seen that the impact strength of the extruded product containing hollow fibers as a reinforcing material is excellent.

When synthetic fibers are used as reinforcing materials for ordinary molded products on a belt conveyor or by filling molds, there are not many restrictions on the length of the fibers, but when using fibers of the same length, the reinforcing effect of hollow fibers is is significantly better.

Examples 3 to 6, Comparative Examples 3 to 6 Samples were prepared using the same composition and conditions as in Example 1, except that the types of fibers and curing conditions were varied, and the Charpy impact values were measured.

The results are shown in Table 4.

Claims (1)

[Claims] 1. An asbestos cement composition for extrusion molding, which contains asbestos and calcium silicate hydrate as main components, and contains hollow synthetic fibers therein.