JP2956039B2 - Manufacturing method of wet cement board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for building boards and the like.
The present invention relates to a method for producing a wet cement board.

[0002]

2. Description of the Related Art A cement board of this type includes cement,
It is a molded and cured product of a mixture of siliceous powder and fibers as a reinforcing material. Conventionally, asbestos has been used as a reinforcing fiber of the cement board. However, asbestos has a problem of environmental pollution, and it is worldwide that asbestos is replaced with other fibers, for example, wood fibers such as pulp. It has become a challenge. Conventionally, cement boards using wood fibers as the reinforcing fibers are cement, siliceous powder, and papermaking dewatering and forming a slurry of a mixture obtained by mixing wood fibers at a predetermined ratio,
Autoclave curing in the temperature range of 100-150 ° C
It is manufactured by a wet method (for example, see JP-A No.
0046).

[0003]

However, in the conventional manufacturing method described above, the temperature of the autoclave curing is too low, and the curing time is prolonged, resulting in poor productivity. On the other hand, when cured at a high temperature of 180 ° C. or higher, the curing time is shortened, but the wood fibers are thermally degraded, and the strength of the product is not increased, and the product becomes brittle.
There was a problem that sufficient bending strength, impact resistance, and cutting property could not be obtained. In order to solve these problems, silicic powder to be mixed is of a specific particle size to prevent reduction in product strength and embrittlement. Doing so raises a new problem that leads to higher product costs.

[0004]

Means for Solving the Problems As means for solving the above-mentioned conventional problems, a mixture of cement, siliceous powder, woody fiber, fibrous sepiolite and / or wollastonite , 1-15% by weight of fiber, fiber
Wei-like sepiolite 3-10 wt%, wollastonite 3
The slurry mixture containing 15% by weight and papermaking dehydrating formation,
Autoclave curing in the temperature range of 160-170 ° C
A method for producing a wet cement board is provided.

Examples of the cement used in the present invention include Portland cement, blast furnace slag cement, silica cement, fly ash cement, alumina cement and the like.

In the present invention, a siliceous powder is added in order to promote the hydraulic reaction of cement. Examples of the siliceous powder include silica sand, silica stone powder, silica fume and the like.

In the present invention, wood fibers and fibrous sepiolite and / or wollastonite are used as reinforcing fibers, and examples of the wood fibers include pulp, wood wool, and wood chips.

Further, in the present invention, besides the above components, if desired, fillers such as shirasu balloon, perlite, fly ash, blast furnace slag, zeolite, sepiolite, bentonite, diatomaceous earth, calcium chloride, magnesium chloride, aluminum sulfate, A cement hardening accelerator such as sodium aluminate and water glass may be added.

[0009] The mixing ratio between the cement and siliceous powder in the usual weight ratio of 3: 7 to 7: is about 3, the wood fibers are from 1 to 15 wt% added warm to a mixture, fibrous sepiolite Usually 3-10 wt%, wollastonite is usually 3 to 15% by weight added pressure. In addition to the above wood fibers, polypropylene fibers, polyethylene fibers, polyester fibers, acrylic fibers, acetate fibers, cotton fibers, bamboo fibers, and the like may be further added.

The mixture is dispersed in water to form a slurry, and the amount of the mixture in the slurry is usually 8 to 15% by weight.

Wollastonite is dispersible in slurry
Since is not good, nonionic surface active agents for improving the dispersibility of further wollastonite in the slurry, cationic surfactants may be amphoteric surfactants are added as the nonionic surfactant, for example Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, etc., and as a cationic surfactant For example, there are trimethylaminoethylalkylamide halide, alkylpyridinium sulfate, alkyltrimethylammonium halide and the like. Sepiolite is also used during slurry papermaking.
Since poor drainage properties may coagulant is added to improve the drainage during papermaking slurry when sepiolite is added, usually aluminum sulfate as the coagulant, alum, polyacrylic Acid soda, polyacrylamide and the like are used. The addition time of the flocculant is after the slurry has been uniformly dispersed by the dispersant, and the amount of addition is 50 to 200 ppm of the total solids.

The slurry prepared as described above is formed into a paper by a usual method, and after the paper formation, if necessary, the paper is dehydrated by press to perform primary curing and autoclave curing. Curing conditions are usually 30 ~ 80 ℃, 6 ~
20 hours, 160-170 for autoclave curing
C, 6 to 10 hours.

[0013]

According to the present invention, as a reinforcing fiber of a hardened material mainly composed of cement and silica, a part of the wood fiber is replaced with fibrous sepiolite and / or wollastonite. The properties are improved by the fibrous sepiolite and / or wollastonite. And the autoclave curing temperature is 160 ℃
The curing time is shortened because of
The following is to prevent the thermal degradation of the wood fiber. One more
Curing at a temperature of 70 ° C. or less enables the combined use with a fiber substance such as a polypropylene fiber.

[0014]

EXAMPLES Table 1 shows the composition of the mixture applied in this example.

[Table 1]

The mixture of the above composition is a slurry having a solid content of 10% by weight, and after papermaking, a press pressure of 150 kg / cm ² (contact pressure).
After being subjected to primary dehydration at 40 ° C. for 12 hours and further autoclaved at a predetermined temperature for 8 hours, the mixture was once left to air-dry and then subjected to the following physical property tests. Flexural strength: Span 15c for a 20 × 20 cm test piece
m and a cross speed of 10 mm / min. Dimensional change rate: The dimensional change rate of a test piece of 20 × 20 cm after immersion in water at room temperature for 24 hours was determined. Impact resistance: The height at which a crack occurred in a test piece when a 530 g iron ball was dropped on a 20 × 20 cm test piece was determined. Cutability: Using a push-off cutter (Kubota single cutter), cut in the papermaking direction (vertical), perpendicular to the papermaking direction (horizontal), diagonally in the papermaking direction (oblique angle), and the amount of force when cutting It was evaluated whether the cutting was successful.・ ・ ・: Desired cutting can be easily performed. C: Cutting as desired cannot be performed.

The results of the above physical property tests are shown in Table 1.
Looking at Table 1, the products of the present invention (Examples 1 to 4) were 17
Comparative Examples 1 to 3 Cured at a Temperature Exceeding 0 ° C. (180 ° C.)
Example 1 using only pulp as a fibrous substance, having bending strength and dimensional stability substantially equal to those of Example 1, but maintaining impact resistance at least twice as high, and cutting ability in most cases requiring only a small amount of force. Even in the case of, the two directions are sufficiently improved, and the impact resistance and the severability are much better than those of the comparative examples, as shown by the same severability as when other fiber materials are mixed. ing. Comparative Example 5 subjected to natural curing is excellent in impact resistance and cutability, but is inferior in dimensional stability.

[0017]

Therefore, in the present invention, by setting the temperature condition during autoclave curing to 160 to 170 ° C., a wet cement board excellent in mechanical strength, dimensional stability, impact resistance, and cutability can be obtained. can get.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 18:26 14:10 14:38)

Claims (1)

(57) [Claims] A mixture of cement, siliceous powder, wood fiber and fibrous sepiolite and / or wollastonite , wherein the wood fiber is 1 to 15 % by weight,
Sepiolite 3-10% by weight, wollastonite 3-15
The slurry of the mixture containing the weight %
A method for producing a wet cement board, comprising autoclaving in a temperature range of 0 to 170 ° C.