JPH0465335A - Production of fiber reinforced cement board - Google Patents

Abstract

PURPOSE:To enhance strength by molding a platelike body from a fiber reinforced cement blend contg. uniformly mixed fibrillated jute and curing the platelike body in an autoclave under a specified pressure for a specified time. CONSTITUTION:A basic blend consisting of cement and silica is uniformly mixed with a prescribed amt. of fibrillated jute as reinforcing fiber. This mixture is molded into a platelike body by a wet process, a paper making process or other process and the platelike body is cured in an autoclave under 8.0-10.0atmG pressure for 9-16 hr to obtain a fiber reinforced cement board having superior strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a fiber-reinforced cement board, and more particularly to a method for manufacturing a fiber-reinforced cement board containing asbestos-free.

[Conventional technology]

BACKGROUND ART Conventionally, architectural wallboards and the like have been widely manufactured from fiber-reinforced cement mixtures by a wet method, a dry method, a paper forming method, or the like.

Traditionally, asbestos has been used very widely.

[Problems with conventional technology]

However, since asbestos causes pollution, there is a strong demand for its use to be restricted or completely abolished, and various reinforcing fibers are being sought to replace them.

Various fibers such as bulb fibers, synthetic resin fibers, and glass fibers have been considered as substitute fibers for asbestos, but bulb fibers have much lower single-filament strength than asbestos, and therefore need to be produced in large quantities in order to obtain a sufficient reinforcing effect. It is necessary to add fibers to the material, which poses a problem in that it loses its nonflammability as a building material.

In addition, synthetic fibers have a problem with their phosphorescence resistance, and when high-temperature, high-pressure curing in an autoclave is performed to improve the strength of the cement matrix, they tend to scratch and deteriorate, making it difficult to achieve a strength commensurate with the addition of synthetic fibers.

Although glass fibers have no problems with single fiber strength or stickiness resistance, they have the disadvantage of low chemical strength against alkalis and deterioration over time.

5. Problems to be Solved by the Invention] In view of the above-mentioned problems, the present invention provides a method for producing a fiber hIi strong cement board using asbestos substitute reinforcing fibers that have strength and chemical resistance comparable to asbestos and can be obtained at low cost. It was created in ε with the purpose of providing.

[Technology that led to solving the problem] That is, the method for manufacturing a fiber-reinforced cement board of the present invention uses fibrillated hemp fibers as reinforcing fibers in the fiber-reinforced cement formulation in the conventional method, and uses the fibrillated hemp fibers as reinforcing fibers. After molding a plate-shaped body from a fiber-reinforced cement mixture with uniformly mixed fibers, the molded body was heated to 8.0 atmG-10, OaLm.
It is characterized by being autoclaved for 9 to 16 hours at G.

[Function] In this invention, fibrillated hemp fibers refer to hemp fibers whose fiber surfaces are fluffed compared to ordinary hemp fibers.

The above-mentioned fibrillated hemp fibers have a larger surface area than normal hemp fibers, and because they are fibrillated, they have good mixability with cement, glue force, and other powdered aggregates, and can be mixed with a mixer or two trowels. However, it can be mixed with good dispersibility.

In this invention, there are wet methods, dry methods, paper forming methods, etc. as means for forming the plate-shaped body, and any of these methods is applicable.

The plate-shaped molded product in which hemp fibers are uniformly dispersed is cured at high temperature and pressure in an autoclave, so that it has even higher strength.

The conditions for autoclave curing are 8.0 atm G-1.
The conditions for 9 to 16 hours at 00a tm G are 8
．． This is because if it is less than 0 atmG, tobermorite, which is a cement permanent product, will not be produced, and 10. OatmQ
This is because if the size is made larger, the hemp fibers will deteriorate.

Further, if the curing time is less than 9 hours, the cement-silica reaction cannot be carried out sufficiently, and as a result, the amount of tobermorite produced is small and strength cannot be obtained. Further, even if curing is carried out for more than 16 hours, no improvement in hardness can be expected and this becomes uneconomical.

C example file Next, the present invention will be explained in detail.

Example 1 To a basic composition consisting of 40% by weight of cement and 54 to 55% by weight of silica sand, 5 to 6% by weight of each reinforcing fiber shown in Table 1 was added to make a total of 100% by weight, then uniformly mixed and dry-processed. A plate-like body with a thickness of 5 tm, a length of 90 an, and a width of 45 ca+ was formed by the method, and was heated to 8.5 a tm C;
) Theo-autoclape-cured conditions.

Next, a JIS No. 4 bending test was performed on these test pieces, and the results were shown in the right column of Table 1.

Table 1 In Table 1, the unit of bending strength test is kg/cIll.
, the unit of deflection is n.

Further, 'Vkll' indicates an example, and 2 to 5 indicate a comparative example.

Example 2 Next, to the basic composition consisting of 59-58% by weight of cement and 35% by weight of silica sand, 6-7% by weight of each of the reinforcing fibers shown in Table 2 were added to make a total of 100% by weight, and after uniformly combining 7 times. ,
Thickness 5n, length 90mm by wet method using Hachenoku paper making machine
A plate-shaped body with a width of 45cm and a width of 8°5atmG
It was cured in an autoclave for 10 hours.

Next, a JIS No. 4 bending test was performed on these test pieces, and the results were shown in the right column of Table 2.

Table 2 In Table 1, the unit of bending strength test is kg/C111
, the deflection level is l.

Moreover, Arashi 1 shows an example, and columns 2 to 5 show comparative examples.

Example 3 To a basic composition consisting of 5011% cement and 46% by weight silica sand, 4% by weight each of the reinforcing fibers shown in Table 3 were added to make a total of 100% by weight. After uniform mixing, the thickness was determined using an extrusion slipper molding machine. A plate with 5 rhymes, 90 cm in length, and 45 c+n in diameter was molded and cured in an autoclave at 8.5 atm G x 1 ohr.

Next, a JI No. 54 bending test was performed on these test pieces, and the results were shown in the right column of Table 3.

Table 3 In Table 1, the unit of bending strength test is kg/cut,
Tawami's honor shows ■.

Moreover, Hiro 1 shows an example, and M2-5 show a comparative example.

As is clear from Tables 1 to 3, the products using fibrillated hemp fibers showed a significant improvement in bending and deformation L2 in all manufacturing methods.

〔effect〕·

Claims (1)

[Claims] (1) Among the fiber-reinforced cement formulations in the conventional method, fibrillated hemp fibers are used as reinforcing fibers, and after forming a plate from a fiber-reinforced cement mixture in which the fibrillated hemp fibers are uniformly mixed, the forming body to 8.0atmG~10
．． A method for producing a fiber-reinforced cement board, which comprises curing in an autoclave at 0 atmG for 9 to 16 hours.