JPH01242452A - Production of inorganic plate - Google Patents

Abstract

PURPOSE:To produce cement plate material having excellent toughness and flexibility even without asbestos by adding fibrillated flax fiber to specified cement material without asbestos, by mixing in dry, thereafter by kneading with water, by extruding and by curing to harden. CONSTITUTION:A inorg. plate is produced by adding 1-3wt.% fibrillated flax fiber to 30-40wt.% cement, 30-40wt.% silica aggregate, 3-8wt.% pulp fiber, 10-20wt.% aggregate and the required amt. of light foamed aggregate, by mixing in dry, thereafter by kneading with an auxiliary for extrusion and water, by extruding and by curing to harden in an usual manner. Thereby, the inorg. plate having form-retraining property and effectively giving bending strength, flexibility, etc., to the molded body after curing to harden without asbestos, can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an inorganic board, and more particularly to an improved method for manufacturing an inorganic board using an asbestos-free cement raw material.

[Conventional technology]

As a reinforcing fiber for cement products, asbestos not only improves the strength of the product, but also imparts bending strength and crack resistance to the uncured product during the above-mentioned cement product manufacturing process, for example, immediately after extrusion in extrusion molding. As is well known, asbestos is extremely useful as a reinforcing material for cement products.However, asbestos causes dust pollution, and on the other hand, its use is gradually being restricted due to resource depletion.

Therefore, various attempts are being made to develop J11i strong fibers to replace asbestos, but at present, nothing satisfactory has yet been achieved.

For example, glass fiber has been proposed for some time as a substitute for asbestos, and has come into practical use to a large extent, but glass fiber generally has low alkali resistance and requires complex processing techniques to improve this property. In addition to the problem of being expensive, glass fibers generally have smooth surfaces, so they tend to "slip through" in uncured board materials.
Therefore, in cases such as extrusion molding where the molded product itself is required to have shape retention immediately after extrusion of the material, there is a problem in that a sufficient reinforcing effect for shape retention cannot be expected.

In addition, although synthetic fibers are useful for improving the shape retention of molded products when they are not cured, they melt when molded products are cured at high temperatures and high pressures, so they cannot be used in products that require such a curing process.
There was a problem that it lacked versatility.

Pulp fibers are a type of fiber that can withstand such curing conditions and exhibit shape-retaining properties, but this pulp fiber alone has a problem with the strength of the board after curing.

Furthermore, although the use of clay minerals has been confirmed to be quite effective according to experiments conducted by the present inventors, there are concerns about dust pollution similar to that of asbestos.

[Problem to be solved by the invention]

In view of the above-mentioned problems, the present invention was made with the object of providing a method for manufacturing an inorganic board that is asbestos-free and can effectively impart shape retention, bending strength, flexibility, etc. to a molded product after curing and hardening. It is something that

[Technology that led to solving the problem] That is, the method for manufacturing an inorganic board of the present invention is based on cement) 30~
40% by weight, 30-41% by weight of siliceous aggregate, 3-8% by weight of pulp fiber, 10-20% by weight of lubricant, and 1-3% by weight of fibrillated hemp fiber added to the necessary lightweight foamed aggregate. After dry mixing, an extrusion aid and water are added and kneaded, the raw materials are extruded, and the obtained molded product is cured by a conventional method.

[Effect]

As mentioned above, various reinforcing fibers can be used as reinforcing fibers for cement compositions, but in addition to the above, hemp, coconut,
There are fibers such as bamboo or straw.

Among these, hemp fibers are superior in elasticity and cutting strength to pulp fibers, and are considered to have more advantageous conditions than pulp fibers.

The present invention focuses on the characteristics of this hemp fiber.

The fibrillated hemp fibers used in the present invention are
This is because hemp fibers have a smooth surface and have poor adhesion to cement when used as is.

In addition, pulverization makes the fibers finer and easier to disperse, and also roughens the surface, improving physical adhesion with the cement matrix and improving intertwining between the fibers. This improves the bending strength and flexibility of the molded plate.

In this invention, the blending amounts of cement and siliceous aggregate are the same as those of conventional ones, and although there is no need to explain specifically, the reason why the content of pulp fiber is 3 to 8% by weight is due to the fiber reinforcing effect and the fiber reinforcing effect of pulp fiber. This is to improve extrudability, and if it is less than 3% by weight, the above effect will not be achieved, and if it is less than 8% by weight.
This is because if it is added in excess of this amount, the water absorbency of the molded plate material will decrease.

In addition, the reason why 10 to 20% by weight of lubricant is added is to improve the bulkiness of the cement raw material by adding hemp fiber and to make the surface smooth during molding. A substance that exhibits viscosity when it contains water is used.

The reason why the amount of these substances added is 10 to 20% by weight is as follows.
If it is less than 10% by weight, the above-mentioned effects cannot be obtained;
This is because if the amount exceeds the weight percent, the bonding strength of the cement matrix will be adversely affected.

Lightweight foamed aggregate is added to reduce the weight of the molded body, and perlite, expanded styrene beads, etc. are used.

Note that the lightweight foamed aggregate is added in an appropriate amount according to the purpose of reducing the weight of the molded product.

Further, the reason why the above raw materials are first dry mixed prior to molding is to improve the uniform miscibility of the fibers and the cement composition, and in particular to uniformly mix the hemp fibers while preventing them from becoming fiber balls.

As the extrusion aid, methylcellulose or the like is used as in the conventional method.

By homogeneously kneading the above-mentioned amount of compounded materials with the addition of water and extrusion molding, a molded product with a smooth surface can be obtained, and by curing and curing, a plate material with excellent strength and flexibility can be manufactured.

〔Example〕

Next, the present invention will be explained in detail.

A is natural hemp fiber cut into a length of 611 Il, B is a natural hemp fiber that has been crushed into fibrils by passing it through a saw-blade crusher, and the mixture is first dry-mixed using a high-speed mixer with the composition shown in Table 1. Next, water was added and kneaded using a kneader, which was then extruded using a vacuum extruder to obtain a product with a thickness of 15 mm and a width of 1 m.
A board with a width of 10 cm was formed, and after being naturally cured for 2.1 hours, it was cured in an autoclave for 8 kg/cm" x 8 hours.

In the table, numbers indicate weight %. Moreover, magnesium hydroxide was used as a lubricant.

When the above test pieces were subjected to a bending strength test and a deflection test, the results shown in Table 2 were obtained.

〔effect〕

As explained above, in this invention, the bending strength using hemp B is excellent, and in particular, the flexibility is improved.

Therefore, according to this invention, it is asbestos-free and strong.
Moreover, the cement board has excellent flexibility! ! ! It becomes possible to build.

Claims (1)

[Claims] (1) Cement 30-40% by weight, siliceous aggregate 30-40%
41% by weight, pulp fiber 3-8% by weight, lubricant 10-20%
After adding 1 to 3% by weight of fibrillated hemp fibers to the required amount of lightweight foamed aggregate and dry mixing, extrusion aid and water are added and kneaded, and the raw material is extruded to obtain a molded product. A method for manufacturing an inorganic board, characterized by curing and hardening by a conventional method.