Wood cement board

Abstract

Provided is a wood cement board that has a pattern of acute-angled and deep recesses and projections on its surface, and that tends not to cause cracking during a hardening and curing process, a drying process, a transportation process and so on. The wood cement board has a pattern of recesses and projections on its surface, in which the distance from the apex of the projections to the rear face is 9 mm or more, and the distance from the apex of the projections to the base point of the recesses is 2 mm or more, and is equal to or less than half the distance from the apex of the projections to the rear face. The average specific gravity of the wood cement board as a whole, and the specific gravities of the projections and the recesses are each 1.1 or more, and the difference between the specific gravity of the projections and the specific gravity of the recesses is less than 0.1.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a wood cement board that has a pattern of recesses and projections on its surface, and more particularly to a wood cement board that has a pattern of acute-angled and deep recesses and projections on its surface, and that tends not to cause cracking during a hardening and curing process, a drying process, a transportation process and soon.[0003]2. Description of Related Art[0004]Wood cement boards are produced by forming a mat using a raw material mixture in which a hydraulic material, a silica-containing material, a wood reinforcement, and as needed, other materials are blended, and then pressing the mat, followed by hardening and curing. Such wood cement boards are widely used as housing members such as exterior building materials and backing materials of tiles. Various patterns formed by recesses and projections, such as a brick pattern and joint grooves, are created on the surface of...

AI Technical Summary

Benefits of technology

[0018]According to this aspect of the present invention, the wood cement board can be produced, for example, by a method for producing a wood cement board, including the steps of: dispersing a raw material mixture onto a template provided with recesses corresponding to the portions of the wood cement board on which projections are formed, while conveying the template, thereby forming a mat; pressurizing only a section of the mat raw material mixture that is layered on the recesses of the template from above; leveling the surface of the partly pressurized mat; and pressing the resulting mat and the template together, followed by hardening and curing. Examples of the method for performing hardening and curing include a method in which hardening and curing is performed at 50 to 80° C. for 6 to 12 hours, followed by natural curing or autoclave curing. Note that the natural curing is a method in which curing is performed with outside air for 3 to 14 days, and the autoclave curing is a method in which curing is performed at 160 to 200° C. under 5 to 8 kgf / cm2 for 5 to 10 hours. In the above-described production method, the mass of the raw material mixture layered on the recesses of the template is larger than the mass of the raw material mixture layered on the projections of the template. That is, the mass of the raw material mixture on the portions of the wood cement board on which the projections are formed is larger than the mass of the mixture on the portions on which the recesses are formed. Accordingly, the mat can be pressed in a uniform manner, so that the specific gravities of the projections and the recesses in the pressed mat are increased to 1.1 or more, and the specific gravity difference between the projections and the recesses is decreased.

[0029]With the wood cement board according to this aspect of the present invention, the distance from the apex of the projections of the wood cement board to the rear face is 9 mm or more, the distance from the apex of the projections to the base point of the recesses is 2 mm or more, and is equal to or less than half the distance from the apex of the projections to the rear face, the average specific gravity of the wood cement board as a whole, and the specific gravities of the projections and the recesses are each 1.1 or more, and the specific gravity difference between the recesses and the projections is less than 0.1. Accordingly, it is possible to achieve a sufficient strength, prevent occurrence of cracking that may possibly occur in the wood cement board during a hardening and curing process, a drying process, a transportation process and so on, and to achieve an improvement in terms of the absorption of a coating material into the substrate during a coating process. Consequently, it is also possible to prevent the problems of a reduction in the strength, the water resistance, the freeze resistance, and the weatherability of a product of the wood cement board, an increase in the amount of the coating material required, and nonuniform coating. Furthermore, the distance from the apex of the projections of the wood cement board to the base point of the recesses is 2 mm or more, and is equal to or less than half the distance from the apex of the projections to the rear face, so that the recess and projection shapes are acute-angled and deep, and have an excellent design quality. When tiles are secure thereto, the tiles tend not to become detached.

Problems solved by technology

However, with the method using an embossing roll, it is difficult to form acute-angled and deep recess and projection shapes.

The method in which the surface of a wood cement board is subjected to cutting requires a cutting process, and therefore involves additional equipment cost and time, leading to poor production efficiency.

Moreover, defective products tend to be produced as a result of cutting failure in the cutting process.

This results in the problems of a significant reduction in the strength, the water resistance, the freeze resistance, the weatherability and the like of the wood cement board, an increase in the amount of the coating material required, and nonuniform coating.

However, the method disclosed in JP 2001-150421A requires the operation of arranging partition plates, and also the operation of removing the partition plates, and therefore has reduced production efficiency.

Moreover, there will be an extra initial cost since various partition plates need to be prepared depending on the depth, the width, and the length of the recesses.

In the case of forming a pattern having a large number of recesses, or a pattern having recesses of various shapes, the operation is more complicated, which results in a further reduction in the production efficiency.

Also in the case of forming recesses that have a long shape, such as those longitudinally traversing the surface of a wood cement board, or that have a wide shape, the workability is reduced and the production efficiency is poor.

Furthermore, the mat layer from which the partition plates have been removed tends to crumble, and it is therefore difficult to achieve a specific gravity difference of less than 0.1 between the projections and the recesses.

Accordingly, the problems of the tendency of cracking in the wood cement board during a hardening and curing process, a drying process, a transportation process and so on, the absorption of a coating material into the substrate of the wood cement board during a coating process, a significant reduction in the strength, the water resistance, the freeze resistance, the weatherability and the like of the wood cement board, an increase in the amount of the coating material required, and nonuniform coating cannot be solved.

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