JPH0890523A - Light-weight board and manufacture thereof - Google Patents

Abstract

PURPOSE: To improve the strength of a light-weight board using a soft fiber plate and an intermediate fiber plate while holding its specific gravity low. CONSTITUTION: A method for manufacturing a light-weight board comprises the steps of coating front and rear surfaces of a woody fiber plate 1 with thermosetting resin C, then inserting it between upper and lower pressing boards mounted with a distance bar a thickness below the thickness α of the plate and applied by the pressure to be restored to the original thickness α after the pressure is released, thermally pressing it, impregnating 3 the front and rear surfaces of the plate 1 with thermosetting resin C, and curing and coating 2 it. The board is manufactured by the method.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Lightweight board made of wood fiberboard used for construction and furniture construction.

[0002]

2. Description of the Related Art Conventionally, soft fiber boards and medium fiber boards have been provided as lightweight boards having a low specific gravity. The strength of the fiberboard is changed in proportion to the specific gravity.
That is, as the specific gravity decreases, the strength also decreases. Therefore, various proposals have been made for the purpose of improving the strength even if the specific gravity is low.

One of them is a method of sticking a reinforcing sheet material on the front and back of a fiber board. As the reinforcing sheet material, a synthetic resin sheet, a non-woven fabric, or the like is used, and is adhered via an adhesive.
However, in this proposal, the resin sheet-like material is expensive and causes a cost increase. Further, there is a drawback that peeling easily occurs between the reinforcing sheet-like material and the fiber board.

As another method, it has been proposed to reduce the weight by using a foaming adhesive or an adhesive mixed with a foaming agent when manufacturing a fiberboard. However, although this proposal can reduce the weight, there are technical problems in improving the strength. Further, the foaming adhesive and the foaming agent are high, which causes a cost increase.

[0005]

[Technical means] A lightweight board in which a thermosetting resin is partially impregnated and applied on the front and back surfaces of a wood fiber board, and a method for producing the same.

[0006]

[Description of Configuration] First, as shown in FIG. 1, a wood fiber board 1 with a thickness α
The thermosetting resin C is applied to the front and back surfaces of. As the wood fiberboard 1, a soft fiberboard or a medium fiberboard is used, and it is particularly effective to apply the fiberboard having a specific gravity of 0.1 to 0.6.

As the thermosetting resin, an adhesive such as an amino resin, a urea resin, a resorcinol resin, a melamine resin, a phenol resin, a urethane resin, a vinyl acetate resin, an epoxy resin, an isocyanate, or a modified resin adhesive thereof is used. To be The thermosetting resin is applied using a coating device such as a roll coater, a flow coater, a spreader, a bar coater, or a spray. In this case, the thermosetting resin is preferably applied in an amount of 100 to 1000 g / m ² . The viscosity is preferably 0.2 to 3.0 poise.

When the specific gravity of the wood fiber board 1 is 0.1 or less, the density is sparse and the thermosetting resin impregnated portion is easily delaminated, and when it is 0.6 or more, the strength of the wood fiber board itself is high. Also, the thermosetting resin does not contribute much to the strength improvement. If the coating amount of the thermosetting resin is 100 g / m ² or less, resin impregnation is not sufficiently performed and uniform coating cannot be performed.

If it is 1000 g / m ² or more, protrusion occurs at the time of pressing and contaminates the wood fiber board 1 itself and the board surface. When the viscosity is 0.2 poise or less, the whole of the wood fiberboard is impregnated and not coated on the front and back layers, and the strength cannot be improved. On the contrary, even when the viscosity is 3.0 poise or more, the impregnation is difficult and the strength is improved. Absent.

Next, as shown in FIG. 1, the wood fiberboard 1 coated with the thermosetting resin C on the front and back is thinner than the thickness α of the wood fiberboard, and the pressure that can restore the original thickness after opening the pressure. Insert a distance bar having such a thickness between the upper and lower clamping plates that are attached, and apply heat.

The distance bar is smaller than the thickness α of the wood fiberboard, and is a thickness at which pressure can be restored to the original thickness after opening, and within 10% of the thickness α of the wood fiberboard. That is, α to 0.90α. If the thickness is -10% or more, that is, 0.90α or less, the clamping pressure is excessively applied, the original thickness α is not restored after opening, and the wood fiber board itself becomes thin (specific gravity becomes high).

In this case, as shown in FIG. 2, the thickness β of the lightweight board p obtained by restoring the original thickness α of the wood fiberboard
Is approximately equal to α. By heat-pressing the wood fiberboard between the upper and lower pressers, the pressure causes the thermosetting resin C on the front and back
Is partially impregnated into the wood fiber board and is applied and cured on the front and back surfaces. In this way, as shown in FIG. 2, a light weight board having a thickness β in which the front and back surfaces of the wood fiber board were partially impregnated with the thermosetting resin and applied was obtained.

In the lightweight board of the present invention, the thermosetting resin-impregnated portions 3 and the coating layer 2 on the front and back surfaces of the wood fiber board 1 have the same function as a conventional reinforcing sheet-like material adhered for reinforcement. The bending strength was improved.

The thermosetting resin may be separately applied to the front surface and the back surface of the wood fiber board and then heat-pressed. Alternatively, different methods may be used in which the thermosetting resin is applied to the front surface, then hot pressed, and then the thermosetting resin is applied to the back surface and then hot pressed.

[0015]

EXAMPLES First, the specific gravity is 0.37 and the bending strength is 47 kg /
Phenolic resin and a viscosity of 1.5 poise are applied to both surfaces of a 15 mm thick wood fiber board made of hardwood wood fibers of cm ² with a spreader at a coating amount of 300 g / m ² on both sides.

Secondly, a wood fiber board coated with a phenol resin is inserted between the upper and lower press plates with a 13.5 mm-thick hot press distance bar attached thereto, and heat pressed. The pressure is 5 kg / cm ² , the temperature is 130 to 150 ° C., and the time is 3
Phenolic resin was impregnated and hardened and coated on the front and back surfaces of the wood fiberboard under the condition of minutes. The lightweight board thus obtained had a thickness of 15 mm, which was the same as that of the wood fiberboard before hot pressing, and the specific gravity was 0.42, which was up about 14%. On the other hand, the bending strength is increased by 70%, 80k
The value was g / cm ² , and significant improvement in bending strength was observed regardless of the increase in specific gravity.

[0017]

EFFECTS OF THE INVENTION The thermosetting resin is impregnated on the front and back surfaces of the wood fiber board, and the thermosetting resin is applied to the front and back surfaces. 2 has a strong adhesion to the wood fiberboard 1, and the resin coatings on the front and back sides contribute to the improvement of bending strength.

[Brief description of drawings]

FIG. 1 shows a state at the time when a thermosetting resin is applied to a wood fiber board.

FIG. 2 also shows a final state.

[Explanation of symbols]

1: Wood fiber board, 2: Thermosetting resin coating layer, 3: Thermosetting resin impregnation layer, C: Thermosetting resin, p: Lightweight board of the present invention.

Claims (2)

[Claims] 1. A lightweight board, characterized in that the front and back surfaces of a wood fiber board are partially impregnated and coated with a thermosetting resin. 2. A distance bar having a thickness smaller than the thickness of the wood fiberboard and having a thickness such that the pressure can be restored to the original thickness after opening after mounting the thermosetting resin on the front and back surfaces of the wood fiberboard. A method for manufacturing a lightweight board, characterized by inserting and pressing between the upper and lower pressers to impregnate the front and back surfaces of the wood fiber board with a thermosetting resin and harden it.