JPH03207606A - Manufacture of fiber-reinforced cement plate - Google Patents

Abstract

PURPOSE:To prevent the melt deterioration of fiber in the above cement plate by providing a first process of carrying out the autoclave curing of a plate- shaped cement body, a second process of carrying out the water curing of the same for a predetermined period or longer, and a third process of drying the same so as to reduce the water content of the same to a fixed ratio or below in the range of specific temperatures. CONSTITUTION:A polypropylene fiber, a polyethylene fiber and a polyvinyl alcohol fiber, which are thermoplastic synthetic resin fibers, are used as a synthetic resin fiber to be added to a cement plate. Autoclave curing in a first process is set to 1 to 3 atm G, and heat at the time of this curing is lowered as much as possible to prevent the heat deterioration of the synthetic resin fiber and to enhance the bonding strength of a cement matrix. A water curing period in a second process is set to 15 days or longer to promote the hardening reaction of cement. Drying in a third process is carried out for removing surplus water contained in the cement plate by the water curing, and a drying temperature is limited to 80 to 110 deg.C to reduce a water content in the cement plate to 2% or less.

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 specifically, a method for manufacturing a fiber-reinforced cement board using an asbestos-free cement composition using a dry roll or molding method. Regarding the manufacturing method.

[Conventional technology]

Conventionally, it is well known that asbestos as a reinforcing fiber for fiber-reinforced cement boards has very excellent performance in shape retention of uncured molded products and reinforcing properties of cured molded products.

However, asbestos causes pollution and resource depletion requires its use to be abolished, and various fibers and methods for producing the same are being sought as reinforcing fibers to replace asbestos.

As these asbestos-replacement fibers, alkali-resistant and heat-resistant pulp fibers are said to be promising for use in cement or molded bodies, and Hewei resin fibers are widely used as they are suitable for their alkali resistance.

[Problems with conventional technology]

However, when the above-mentioned pulp fibers are mixed and dispersed with raw materials such as powdered cement and silica, the fibers tend to become entangled with each other and form fiber balls, so-called clumps. There is a problem in that it does not contribute to the strength of the cement matrix.

On the other hand, it is possible to use Gakkai resin fiber as a reinforcing fiber that does not form lumps, but in this case, the fiber may deteriorate or melt due to heat during autoclave treatment, so the reinforcing effect commensurate with the addition is still insufficient. There was a problem that it was not possible to obtain

[Problem to be solved by the invention]

This invention was made in view of the above-mentioned problems, with the object of providing a manufacturing method that does not cause melting and deterioration of the fibers even when using resin fibers.

[Technology that led to solving the problem]

That is, the method for producing a fiber-reinforced cement board of the present invention uses 10 inorganic raw materials such as cement, aggregate, etc. by a conventional method.
A cement mixture made by adding 1 part by weight of synthetic resin fiber to 0 part by weight is mixed uniformly, and then the raw materials are fed in layers onto a belt conveyor, water is added, and the mixture is continuously compressed using rolls. The plate-shaped excipient obtained by molding is heated to 1 to 3 atm.
The first step is autoclave curing in G, the second step is underwater curing for 15 days or more, and the third step is drying at a temperature of 80°C to 110°C to a moisture content of 2% or less. It is something.

[Effect]

In this invention, polypropylene fibers, polyethylene fibers, and polyvinyl alcohol fibers, which are thermoplastic synthetic resin fibers, are used as the additive resin fibers.

This is because these fibers are easily available.

The reason why the autoclave curing in the first step is set to 1 to 3 atmG is to keep the heat during curing as low as possible, to prevent thermal deterioration of the Hewei resin fibers, and to increase the bonding strength of the cementumol and lithox.

If it exceeds 3 atmG, the bending strength of the product will decrease due to thermal deterioration of the fibers, and if it is less than latmG, the bonding strength of the matrix will be insufficient, and sufficient product strength will still not be obtained.

The reason why the underwater curing in the second step was carried out for 15 days or more was to compensate for the insufficient conditions caused by the autoclave curing and to promote the cement hardening reaction to the same level as 8.5 atm x 10 hr.

Therefore, if the curing period is shorter than 15 days, sufficient bending strength will not be obtained.

The third step, drying, is to remove excess water contained in the water curing, and the drying temperature for this purpose is set at 80°C to 11°C.
The reason for limiting the temperature to 0°C is that although it is possible to reduce the water content to 2% or less at an early stage at temperatures above 110°C, the thermoplastic fibers deteriorate and the strength of the reinforcing fibers cannot be guaranteed, and below 80°C. This is because the drying process takes too much time and production efficiency deteriorates.

This invention is a manufacturing method that does not cause deterioration of Hewei resin fibers by using low-temperature and low-pressure treatment instead of the conventional high-temperature and high-pressure treatment. It is possible to create products.

〔Example〕

An embodiment of this invention will be described.

Example A cement inorganic raw material consisting of 90 parts by weight of cement and 10 parts by weight of aggregate, Voripro fiber, polyethylene fiber, and polyvinyl alcohol (PVA) fiber shown in Table 1 were prepared, and the cement inorganic raw material was first dry-mixed. Hewei resin fibers were added and dry mixed, these raw materials were supplied in a layered manner onto a shaped belt, and compression molded using a shaped roll after sprinkling with water in a conventional manner to a thickness of 4.5 mm. Length 180ccm Width 45
A plate material of cm was molded.

The molded body was then cured in an autoclave at 1 to 3 atmG for 10 hours, further cured in water for 15 days, and then sent to a dryer at a temperature of 105° C. and dried for 24 hours. The moisture content of the obtained plate material was 2% or less.

Next, a strength test according to JISA No. was conducted, and Table 2
The results are shown in.

Comparative Example 1 A product with the same composition as in the example shown in Table 1 was compressed and shaped using a pressing roll in the same manner as above, with a thickness of 4.5 mm and a length of 180 cm.
, a board with a width of 45 cm is 1.0 to B. as shown in Table 3.
Only autoclave curing was performed for 10 hours in OatmG to cure and harden.

The test results of this plate material by No. J rsd are shown in Table 3.

Comparative Example 2 A plate-shaped body was dry-shaped in the same manner as in the example, and the thickness was 4.5 m.
A plate material having a length of 180 cm and a width of 45 cm was obtained, and as shown in Table 4, it was cured in water for 5 to 20 days without being autoclaved.

The strength test results for this product according to JIS No. d are shown in Table 4.

〔effect〕

As explained above, this invention is designed to cure at low temperatures, so deterioration due to heat can be avoided by using Hewei resin fibers as reinforcing fibers.In addition, since the lack of strength due to low temperature curing is compensated for by underwater curing, it is possible to It is possible to form a board with excellent strength comparable to that of one cured under high pressure conditions.

Claims (1)

[Claims] (1) A cement mixture made by adding 1 part by weight of synthetic resin fiber to 100 parts by weight of an inorganic raw material made of cement, aggregate, etc. by a conventional method is mixed uniformly, and then,
The raw material is supplied in a layered manner onto a forming belt conveyor, and after adding water, it is continuously compression-molded using rolls, and the obtained plate-shaped excipient is
The first step is autoclave curing at 3 atmG;
A second step of curing in water for 5 days or more and a temperature of 80°C to 1
A method for manufacturing a fiber-reinforced cement board, comprising a third step of drying at 10°C to reduce the moisture content to 2% or less.