Particle board and method of making the same

Abstract

The object of the present invention is to provide a particle board which is improved at its entirety in the resistance to water without impairing its performance as a bearing board member and provide a method of making the particle board. A particle board of the invention having wooden materials coated with an adhesive of a thermosetting resin and pressurized with being heated, the particle board comprising: a core layer and face layers provided on both, front and back, sides of the core layer, wherein the wooden materials of the face layer are smaller in the average particle diameter than the wooden material of the core layer; and voids between the adjacent wooden materials in the face layer and the core layer are filled with resin particles of a thermoplastic resin by being pressurized with being heated.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a particle board for use as a structural material or a furniture component and a method of making the same.[0003] 2. Description of the Related Arts[0004] Particle boards are panel-like products made by bonding wooden materials with an adhesive. Most of such particle boards have a three-layer construction consisting mainly of a core layer and two face layers formed on both, front and back, sides of the core layer. The core layer comprises relatively large sized wooden materials hence creating visually recognizable voids. To the contrary, the face layers comprise relatively small sized wooden materials hence being close structure.[0005] Such particle boards are made by supplying wooden materials with a spray of an urethane adhesive, forming, and pressurizing them with heating. The urethane adhesive is hardened when its isocyanate reacts on a hydroxy functional group in the wooden materials. The amount of the adhe...

AI Technical Summary

Benefits of technology

[0011] In the particle board of the present invention, the voids between the wooden materials are filled with the resin particles of the thermoplastic and the wooden materials are then pressurized while being heated. This allows the particle board to be filled at not only the surfaces but also the interior with the thermoplastic resin having hydrophobic character. Accordingly, the resistance to water of the particle board will be improved throughout its whole structure.

[0014] This permits the resin particles and wooden materials in the face layers to be smaller than those in the core layer. Hence, the size of each resin particle is approximately close to the size of each wooden material in each of the face layers and the core layer. More particularly, the non-uniformity in the mixture due to a difference in the specific gravity between the wooden material (having a specific gravity of 0.4 to 0.6) and the resin particle (having a specific gravity of 0.9) is minimized. Accordingly, the thermoplastic resin particles providing a higher level of the resistance to water will be dispersed uniformly in the whole particle board, thus preventing the resistance to water from being varied locally in the particle board.

Problems solved by technology

The core layer comprises relatively large sized wooden materials hence creating visually recognizable voids.

However, while the particle board is functioning sufficiently as a bearing board member, which is unfavorable in the resistance to water because its components are mainly wooden materials.

As the particle board is poor in the function of resistance to water, its water-content gradient may cause deflections and dimensional changes of its structure or its water remaining may result in the development of mould and the decomposition of wooden constituents.

However, the prevention of water penetration through the butt ends into the particle board has not yet been achieved.

When the rate is smaller than 0.5, the mixture of the wooden materials and the resin particles in the face layers will hardly be uniform hence lowering the resistance to water of the particle board.

When the rate is smaller than 0.5, the mixture of the wooden materials and the resin particles in the core layer will hardly be uniform hence lowering the resistance to water of the particle board.

This prevents the mixture from being not uniform due to a difference in the specific gravity between the two different components.

If the temperature is lower than 150.degree. C., the thermosetting resin may fail to be hardened.

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