JPH0456726B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing particle board, and in particular, the present invention relates to a method for manufacturing particle board, and in particular, a high viscosity adhesive is used for the former and a low viscosity adhesive is used for the latter at the same rate or at a higher rate than the latter. The present invention relates to a method for manufacturing particle board, which comprises applying a large amount of the former and applying the former separately, then mixing the two and hot pressing the mixture to manufacture particle board. [Background of the Invention] Since the end surface of particle board is a rough surface, even when paint is applied, a large amount of paint is absorbed, making it impossible to create a beautiful surface. Even if an attempt was made to attach the decorative tape via an adhesive, the adhesive would penetrate and the decorative tape could not be reliably attached to the wood end surface, resulting in peeling. [Prior technology] In order to make the wooden surface of particle board smooth, wood fibers were mixed into the wood chips for particle board, and after mixing them, adhesive was applied to produce particle board. but,
It had the following shortcomings: Wood fibers containing fine powder and fine fibers are more easily coated with adhesive than wood chips for particle board (referred to as particles), and adhesive does not stick to the wood chips much, reducing adhesive strength. In addition, a lot of stickiness occurred on the wood fiber, which caused disturbances in forming and the occurrence of resin spots (clumps of resin). Therefore, in order to eliminate stickiness of wood fibers and improve forming properties, it is necessary to use adhesives with low viscosity and low molecular weight, but when such adhesives are used, the applied adhesive Penetrated into the interior of the wood chips in large quantities, reducing adhesive strength. [Purpose of the Invention] The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to provide a method for mixing wood fibers obtained by a dry or wet refiner with wood chips for particle board. Then, a high viscosity adhesive is applied to the former and a low viscosity adhesive is applied to the latter in equal proportions or in a larger amount of the former than the latter, respectively, to the wood chips and wood fibers.
The object of the present invention is to provide a method for manufacturing particle board by subsequently mixing the two and hot pressing the mixture. [Example] A three-layer board with a thickness of 20 mm was manufactured under the following conditions. Wood chips: Lauan wood chips were passed through a ring flaker with a 0.8 mm blade, and the resulting chips were sieved through a 1.6 mm sieve. A chip of 1.6 mm or less was used for the surface layer, and a chip of 1.6 mm or more was used for the inner layer. After drying, the moisture content was adjusted to 5%. Wood fiber: lauan wood chips with a moisture content of 60%
It was subjected to dry refining (SDR) in this condition. The dry moisture content was 5%. Board specific gravity...0.70 Heat and pressure conditions...Temperature: 160℃, Pressure: 25Kg/ ^cm2 , Time: 10 minutes Composition ratio...Surface layer: Inner layer = 2:1 (weight ratio) Mixing ratio...Wood chips: Wood fiber =1:
1. Adhesives and their addition rates...Table 1 Under these conditions, particle boards (A), (B), and (C) were manufactured by the particle board manufacturing method of the present invention. As for the comparative example, a conventional particle board production method was used, that is, a particle board was produced by mixing wood chips and wood fibers and then applying an adhesive. The particle boards manufactured under (A), (B), (C) and the comparative example were subjected to (1) bending tests, (2) peeling tests, and (3) surface condition evaluations, and the following results were obtained.

【table】

〔Effect of the invention〕

By manufacturing particle board by separately applying the required amount of the desired adhesive to wood chips and wood fibers, the following advantages arise: (1) The amount of adhesive applied to wood chips and wood fibers can be adjusted separately. For example, by applying a large amount of adhesive to wood chips and a small amount of adhesive to wood fiber, it is possible to eliminate stickiness of the fiber, improve forming suitability, and improve adhesive strength. (2) By applying a low-viscosity, low-molecular-weight, easy-to-penetrate adhesive to the wood fibers, and by applying a high-viscosity, high-molecular-weight adhesive to the wood chips, they have excellent forming properties and excellent adhesion. Can manifest power. (3) Separate adhesives may be used for wood fiber and wood chips. For example, phenolic resin (curing temperature is higher than urea melamine resin and also expensive) is used for wood fiber.
Urea-melamine resin can be used for wood chips. By using phenolic resin, when applying adhesive to the fibers on the blow line (the line where the fibers are blown from the refiner to the dryer), the precure in the dryer can be alleviated and excellent adhesive strength can be obtained. can. The above example is about a three-layer board, but
A similar effect can be obtained even in the case of a single layer board.

Claims (1)

[Claims] 1. For wood chips and wood fibers, apply a high viscosity adhesive to the former and a low viscosity adhesive to the latter.
A method for producing particle board, characterized in that the particles are pre-applied separately so that the ratio of the former to the raw material is the same or increases, the two are mixed, and the mixture is hot-pressed to produce particle board.