JPH0248480A - Curing of fiber cement plate - Google Patents

Abstract

PURPOSE:To obtain the title cement plate exhibiting reinforcing effects corresponding to an amount of fiber added even in reinforcing fibers readily being dried or having low temperature resistance in a reduced fraction defective by forming molded articles from a cement mixture blended with organic fibers as reinforcing fibers and curing under a specific condition. CONSTITUTION:Molded articles are formed from a cement mixture blended with organic fibers (e.g., pulp fibers or PP fibers) as reinforcing fibers, the molded articles are hardened at once so as not to disperse the molded articles into water, then immersed in water and cured at high temperature (e.g., <=100 deg.C) under high pressure (e.g., 8.5 atmospheric pressure in the case of pulp fiber and 6 atmospheric pressure in the case of PP fibers) in a state as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for curing fiber cement boards, and more particularly to a method for curing fiber cement boards using organic fibers such as pulp fibers or synthetic fibers as reinforcing fibers.

[Conventional technology]

It is well known that asbestos fiber is useful as a reinforcing fiber for conventional cement products, but its use has been forced to be discontinued due to both the fact that it causes dust pollution and the depletion of resources.
At present, various alternative fibers to asbestos are being explored.

The use of organic fibers such as pulp fibers or polypropylene fibers as substitute fibers for asbestos has been proposed and widely implemented.

[Problems with conventional technology]

By the way, the inner valve fibers of the above-mentioned machine fibers have poor adhesion to cement and are also easier to dry than cement particles, so they have the disadvantage of further deteriorating their adhesion to the cement matrix.

In addition, shrinkage occurs due to drying, and due to these factors, when autoflave curing is performed, products tend to crack, resulting in a high rate of defective products.

In addition, in the case of organic synthetic fibers such as polypropylene fibers, the surface is smooth, so they have poor adhesion to the cement matrix, making it difficult to obtain sufficient reinforcing effects. There was a drawback that the reinforcing effect could be lost due to the fibers deteriorating or melting.

[Problem to be solved by the invention]

This invention provides a method for curing fiber cement boards that eliminates all the drawbacks caused by organic fibers in the curing process of cement products using organic fibers, and can significantly reduce the incidence of defects. It was done for that purpose.

[Technology that led to solving the problem]

That is, the method for curing fiber cement boards of the present invention involves forming a molded body from a cement mixture containing organic fibers as reinforcing fibers, hardening the molded body once to such an extent that it will not be dispersed in water, and then immersing it in water. It is characterized by performing high temperature and high pressure curing under the following conditions.

[Effect]

As mentioned above, pulp fibers are prone to drying, and this drying causes various problems.

Therefore, in order to prevent the pulp fibers from drying out, the pulp fibers are cured in water to supply the necessary moisture to the valve fibers, and at the same time, in order to increase the bonding strength of the cement matrix, high temperature and high pressure curing is carried out while immersed in water. I will do it.

Therefore, drying of the pulp can be completely prevented, and at the same time, the bonding strength due to high temperature and pressure can be improved, and the bending strength and flexibility of the plate material as a whole can be improved.

Furthermore, since the cement board that is cured at high temperature and high pressure is immersed in ice at one point, the temperature is limited to 100° C. at most, so that deterioration and melting of organic synthetic fibers can be sufficiently prevented from IK.

〔Example〕

Next, the present invention will be explained in detail.

(Example 1) Using the cement mixture raw materials shown in Table 1, a thickness of 5 cm was obtained by dry method.
After molding the plate material of IIllI+ and leaving it for one day to prevent the plate material from dispersing, the plate material was immersed in water for two days, and in the case of valve fiber, the conditions were 8.5 atm x 10 hours, and polypropylene fiber. In the case of 5 atm X1
Autoclave conditions were performed for 0 hours.

(Example 2) A fiber cement board was manufactured by a wet papermaking method using fly afayu as the silica component and the cement mixture raw materials shown in Table 2. After the fiber cement board was once hardened to the extent that it could be immersed in water, it was cured for one day. 3. Immersed in water, and while immersed, both Example 2-1.2-2. Oatm X 10hr
Autoclave curing was performed under the following conditions.

(Comparative example) Example 1 (1-1, 1-2) and Example 2 (2-
1, 2-2) Using exactly the same blended raw materials and amounts, a plate shape of the same thickness was formed by a dry method and a wet method, respectively, and after primary curing of this molded product in air for one day, it was immersed in water. The curing was carried out under the same autoclave conditions as in each of the above Examples.

Examples 1-1 to 2 and Comparative Example 1- after autoclave curing
1 to 2, the JISA bending test was also carried out in Example 2-1.
-2 and Comparative Examples 2-1 and 2-2 were subjected to a JIS No. 3 bending test, and the results shown in Table 3 were obtained.

〔effect〕

Claims (1)

[Claims] (1) Molding a molded body from a cement mixture containing organic fibers as reinforcing fibers, once hardening the molded body to an extent that it will not be dispersed in water, immersing it in water, and curing at high temperature and high pressure in that state. A method for curing pulp fiber cement boards characterized by: