JPS58147345A - Preparation of particleboard - Google Patents

Abstract

PURPOSE:To prepare a particleboard high in strength and low in water absorptive swelling ratio, by a method wherein stock chips are treated with an alkali aqueous solution and the treated chips are used by subjecting the same to heating and pressing treatments in the presence of steam. CONSTITUTION:Chips prepared by a predetermined method are treated with an alkali aqueous solution and the treated chips are subsequently thrown into a hermetically closed container such as an autoclave. In the next step. heated steam is injected into said container to hold the interior thereof to definite pressure. Wood chips absorb moisture to a saturated state in the container. This moisture saturated chips are taken out and formed into a particleboard by a known method. By this method, the internal bonding strength of the particleboard is made excellent and, as the result, water absorptive swelling characteristics there of are enhanced.

Description

[Detailed Description of the Invention] [Objective] To provide a method for producing a so-called particle board, in which entanglement between chips is promoted by swelling the chips, and the particle board has high strength and a low water absorption swelling rate. [Background Art] Particle Board F, which uses ordinary chips, has lower strength (and swells more due to water absorption) than plywood, which is a major drawback as a substrate.

In order to improve this shortcoming in terms of strength, techniques have been developed in various fields to improve strength by using relatively large chips, but apart from strength, sufficient results have not been achieved in terms of improving water absorption.

This invention was made in view of the above circumstances.

[Disclosure of the Invention] Particle board is usually manufactured as follows. That is, wood scraps and scrap wood are prepared, and they are processed into chips by a chipper. Apply adhesive to this chip. The method involves placing chips in a rotating drum and spraying them with adhesive. The adhesive is usually of a thermosetting type, and the adhesive-coated chips are then fed into a forming machine. At this point, the chips are scattered on the moving belt and adjusted to a constant thickness. The material formed into a mat shape in this way is heated and pressed to form a board.

There are no restrictions on the raw material chips used in this invention, and the raw material chip manufacturing method or the chip used in the ordinary particle board manufacturing method is used.

Therefore, also in the present invention, chips can be prepared by a known method.

The feature of this invention lies in the pretreatment of the chips used. That is, a chip prepared by a predetermined method is treated with an alkaline aqueous solution, and then the treated chip is placed in a sealable container such as an autoclave, and the container is sealed. Then, heated steam is injected to maintain a constant pressure. That is, heat and pressure treatment is performed in the presence of water vapor. Inside the container, the wood chips absorb moisture to the point of saturation. The chip in this state is taken out and used. At this time, it is preferable to take out the treated chips by releasing them all at once into the atmosphere.

By performing the above-mentioned treatment (referred to as swelling treatment), the wood chips take on a thinner fibrous shape. The thus treated chips are made into particle board using a known method.

Although the conditions for chip pretreatment in this invention are not intended to be limited, the following conditions are recommended.

Puffing treatment conditions> Alkaline aqueous solution: preferably about 0.1 to 2.0% of sodium hydroxide, potassium hydroxide, etc. (not limited thereto).

Pressure: Preferably in the range of 5 to 15 kg/cIa. If the pressure is lower than this range, processing will be insufficient, and if it is higher, the chips will become smaller and the strength will tend to decrease.

Processing time: 25-10 minutes.

A method for manufacturing a board using the chips obtained as described above may be carried out using known methods and conditions, but preferred conditions include the following conditions.

<Particle board manufacturing conditions> Adhesive M used: Urea, urea melamine, and phenol resin are used, but this is not intended to be limiting.

Adhesive usage amount: The range of 3 to 20% is preferable, and it is used according to the purpose within this range.

Molding pressure: preferably in the range of 10 to 50-/-,
By increasing the pressure and using more chips, the specific gravity of the board can be increased. Molding time: 5 to 20 minutes is preferable, and this IIWJ
The thickness of the board is determined by law as appropriate.

Example 1 Acicular chips of red lauan were used as a raw material, pretreated with a 0.1% aqueous sodium hydroxide solution, and then the treated chips were mixed with urea melamine resin adhesive and heated to a pressure of 1
A board weighing 0 kg/- and having a thickness of 20 cranes was manufactured. The specific gravity of this board is 0.60? Ta.

Example 2 A 0.5% sodium hydroxide 5-rum aqueous solution was used as the alkaline aqueous solution, and the swelling treatment was performed at a pressure of 10.
/ cd, 5 minutes, other conditions were as in Example 1.
It was conducted with the same content.

The specific gravity of the obtained board was 0.61.

Example 3 A 1.0% aqueous sodium hydroxide solution was used as the alkaline aqueous solution, and a pressure of 15 kg/cd was used for the swelling treatment.
The test was conducted under the same conditions as in Example 1 except that the test time was 10 minutes.

The specific gravity of the obtained board was 0.63.

Comparative Example A board was manufactured in the same manner as in Example 1 using chips that were not subjected to swelling treatment.

The specific gravity of the obtained board was 0.61.

The physical properties of the boards obtained in the above Examples and Comparative Examples are shown in the table below.

6- [Effects] The characteristics of the chips according to the present invention are that the filling material (mainly lignin) in the wood that binds the cellulose fibers or micelles is removed by the swelling treatment, and the chips Boards manufactured using such chips have excellent internal cohesiveness, as the long state is separated into thin bundles and these surfaces remain active and are re-formed into a board. It has the effect of improving the water absorption and swelling properties of the board.

patent applicant Matsushita Electric Works Co., Ltd. agent patent attorney Toshimaru Takemoto (2 idiots)

Claims (1)

[Claims] (1) A method for producing particle board, which is characterized in that the raw material chips to be used are previously treated with an aqueous alkali solution and then subjected to heating and pressure treatment in the presence of water vapor.