JPH08295551A - Cement-base inorganic board - Google Patents

Abstract

PURPOSE: To improve the water absorptivity, dimensional stability and resistance to freezing, thawing and environmental stain by a paint by dispersing a woody reinforcement treated with ammonia in a cement-base hardened inorg. hydraulic material. CONSTITUTION: A woody reinforcement is sipped in liq. ammonia for 5 to 20sec, discharged, washed with water and heated to remove the remaining ammonia. Since a nodule is formed when waste paper is used as the reinforcement, the waste paper is dispersed in water and opened by an opening machine. The treated waste paper is added by 25-50wt.% to the reinforcement. Subsequently, 1-15wt.%, ammonia-treated woody material based on the hydraulic material, <=30 pts.wt. of a lightweight aggregate, based on the total solid, at need, further a hardening accelerator, a waterproofing agent and a water repellent are added to form a 10-12wt.% slurry, and the slurry is formed into sheet, vacuum- dehydrated and cured at 70-90 deg.C for 20-30hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement-based inorganic board used as a building material.

[0002]

BACKGROUND OF THE INVENTION Conventional cement-based inorganic boards have used asbestos as a reinforcing material. However, asbestos has its fine fibers scattered in the air, and if a person inhales it, it causes serious damage to health. Therefore, recently, wood reinforcing materials such as pulp, wood chips and wood fibers have been used in place of asbestos. Since the above wood reinforcing material does not generate fine fibers, there is no problem of environmental pollution, but since the water absorbency is larger than that of asbestos, the cement-based inorganic board using this is said to be inferior in dimensional stability and freeze-thaw resistance due to water absorption. There is a problem.

[0003]

2. Description of the Related Art Conventionally, a water repellent has been used to improve water absorption and dimensional stability of a cement-based inorganic board using a wood reinforcing material (for example, JP-A-58-72405 and JP-A-58-72405). 6-321602). As the water repellent, fatty acid metal salt type, fatty acid ester type and paraffin type substances are used.

[0004]

However, the above water-repellent agent is not sufficiently durable, and especially when the cement-based inorganic plate is used as an outer wall plate exposed to the external environment, the water-absorption of the cement-based inorganic plate with time elapses. Sex tends to increase,
Therefore, there is a problem that the dimensional stability and freeze-thaw resistance of the cement-based inorganic board are deteriorated.

[0005]

As a means for solving the above-mentioned conventional problems, the present invention is characterized in that an ammonia-treated wood reinforcing material is dispersed in a hardened cement-based inorganic hydraulic material. The present invention provides a cement-based inorganic board, wherein a part or all of the wood reinforcing material is preferably waste paper pulp, the waste paper pulp is preferably newsprint paper, and further, the newsprint paper is wood reinforcing material. It is desirable to make up 25 to 50% by weight of the material.

[Cement-based inorganic hydraulic material] The cement-based inorganic hydraulic material used in the present invention is a hydraulic inorganic powder containing calcium silicate as a main component. As, for example, Portland cement, or blast furnace cement mixed with Portland cement blast furnace slag, fly ash cement mixed with fly ash, volcanic ash, silica fume, silica cement mixed silica material such as clay, alumina cement, blast furnace slag, etc. is there.

[Wood Reinforcement Material] The wood reinforcement material used in the present invention includes wood flour, wood wool, wood chips, wood fibers, wood pulp, softwood pulp, hardwood pulp, wood fiber bundles, waste paper pulp, especially newspaper waste paper pulp, Hemp fiber, bacas, chaff,
There are rice straw and bamboo fiber. The wood reinforcing material is usually added in an amount of about 1 to 15% by weight based on the cement-based inorganic hydraulic material. Since the waste paper pulp as a wood reinforcing material, especially newspaper waste paper pulp, is composed of ground pulp, the fiber length is short and the reinforcing effect is small. However, by adding up to 50% by weight of the waste paper pulp to other wood-based reinforcing materials, the reinforcing effect of the wood-based reinforcing materials is secured. In addition, the waste paper pulp is added to the wood reinforcing material in an amount of 25
When it is added in an amount of not less than wt%, the waste paper pulp swells in water to give an appropriate viscosity to the kneaded material of the raw material and water, and the molding workability is improved in the case of extrusion molding. Conventionally, when asbestos was used, a proper viscosity was given to the kneaded material of the raw material and water due to the swelling of asbestos with water. However, when asbestos is replaced with a wood reinforcing material other than waste paper pulp, it does not have a thickening effect like asbestos, so it was necessary to add a thickener separately. However, if the waste paper pulp, especially newspaper waste paper pulp, is used in the wood reinforcing material in an amount of 25% by weight or more as in the present invention, the addition of the above-mentioned thickening agent becomes unnecessary. In the present invention, the wood reinforcing material is treated with ammonia. That is, the wood reinforcing material is immersed in liquid ammonia for about 5 to 20 seconds, and then the wood reinforcing material is taken out and washed with water or heated by a drum cylinder or the like to remove residual ammonia. When a drum cylinder is used, most of the evaporated ammonia can be recovered by the Sanfosset method equipped with a recovery device. Since the above-mentioned ammonia-treated wood reinforcing material forms a nodule, especially in the case of waste paper pulp, it is desirable to disperse it in water and disintegrate it with a defibrating material. According to the above-mentioned ammonia treatment, the elasticity of the cellulose fibers in the wood reinforcing material becomes small, and even if the wood reinforcing material in the product absorbs water, the elastic deformation of the wood reinforcing material becomes very small.

[Aggregate] In the present invention, an aggregate, particularly a lightweight aggregate, may be added in addition to the cement-based inorganic hydraulic material and the wood reinforcing material. As the lightweight aggregate, inorganic foams such as pearlite, shirasu balloon, expanded shale, expanded clay, calcined diatomaceous earth, fly ash, coal waste, and crushed foam concrete are used. The above lightweight aggregate is usually added in an amount of 30 parts by weight or less based on the total solid content of the mixture.

[Third component] In the above composition, if desired, a curing accelerator such as aluminum sulfate, magnesium sulfate, calcium sulfate, aluminate, alkali metal silicate, wax, wax, paraffin, surfactant, A waterproofing agent such as silicon or a water repellent agent may be added.

[Production of Cement-Based Inorganic Board] The cement-based inorganic board of the present invention is produced mainly by a wet method such as a papermaking method or an extrusion molding method. In the papermaking method, the above raw material mixture is dispersed in water to form a slurry of about 10 to 12% by weight, the slurry is made on a porous sheet such as felt, and a vacuum device is further provided on the back surface of the porous sheet. The paper sheet obtained by contact and vacuum dehydration is wound up on a making roll if desired and laminated to several layers to obtain a desired thickness, and then the paper sheet is naturally cured or autoclaved to be cement-based inorganic hydraulic material. Is cured by hydration, but the curing conditions are usually 70 to 90 ° C. and 20 to 30 hours. In the case of the extrusion molding method, water is added to the above raw material mixture to adjust the water content to 50 to 80% by weight and kneaded, and the kneaded product is extruded by an extruder. At this time, as described above, when a waste paper pulp, particularly a newspaper waste paper pulp is used, an appropriate viscosity is imparted to the kneaded product, and the extrusion workability is improved, so that it is not necessary to add a thickener.

[0011]

The wood reinforcing material used in the present invention does not become fine fibers and does not scatter in the air. The stretchability is also reduced by the ammonia treatment. Therefore, the cement-based inorganic board product of the present invention has little dimensional change even when it absorbs water. In the present invention, the use of waste paper pulp, especially newspaper waste paper pulp,
These waste paper pulps, which have not been effectively used in the past, are effectively used, and the waste paper pulp gives the raw material kneaded product a viscosity suitable for extrusion molding.

[0012]

【Example】

[Examples and Comparative Examples] Newspaper waste pulp, recycled pulp,
Softwood pulp was mixed with the composition shown in Table 1 and immersed in liquid ammonia for 15 seconds, then residual ammonia was removed by the Sanfosset method, dispersed in water and defibrated with a defibrator to give a pulp concentration of 3-4. Prepare a wt% dispersion. The raw materials shown in Table 1 are further added to the dispersion and mixed to obtain a slurry having a solid content of 11% by weight. A paper sheet having a thickness of 12 mm is obtained by paper-making the slurry on felt, dehydrating in vacuum and further laminating. The papermaking sheet is cured by curing at 80 ° C. for 24 hours to prepare a cement-based inorganic board sample. As a comparison, a cement-based inorganic plate sample using pulp without ammonia treatment was prepared in the same manner as the sample of the example. The physical properties of the above sample were measured. The results are shown in Table 1.

[Table 1]

From Table 1, it can be seen that the examples using the pulp treated with ammonia have a smaller water absorption elongation and improved dimensional stability as compared with the comparative examples not treated with ammonia.

[0014]

INDUSTRIAL APPLICABILITY In the present invention, a cement-based inorganic board having good dimensional stability can be manufactured by using a wood reinforcing material which does not pollute the environment instead of asbestos.

Claims (4)

[Claims] 1. A cement-based inorganic board, characterized in that a wood-based reinforcing material treated with ammonia is dispersed in a hardened cement-based inorganic hydraulic material. 2. The cement-based inorganic board according to claim 1, wherein a part or all of the wood reinforcing material is waste paper pulp. 3. The cement-based inorganic board according to claim 1, wherein the waste paper pulp is newspaper waste paper. 4. The cement-based inorganic board according to claim 3, wherein the newspaper wastepaper comprises 25 to 50% by weight of the wood reinforcing material.