JPS61181570A - Coating method for woody fibrous plate - Google Patents

Abstract

PURPOSE:To prevent the discoloring such as the yellowing and the browning and to obtain a beautiful stabled coated film by bleach-treating the surface of a woody fibrous plate and thereafter coating this surface with a water paint. CONSTITUTION:The surface of a woody fibrous plate is bleach-treated with a bleaching agent wherein an alkali agent such as sodium hydroxide is used for a hydrogen peroxide bleaching agent. When the coated surface of the bleaching liquid is heat-treated with a heated roll or a heated disk immediately thereafter, the decomposition velocity of the hydrogen peroxide bleaching agent is accelerated and the colored components contained in lignin of the surface layer of the woody fibrous plate are decomposed in a short time and it is smoothed together with the bleaching effect by suppressing the fluffing of the wood fiber. Then a water paint is coated and dried. In such a way, the color drift is removed and the coated surface excellent in the adhesive properties on the paint is formed and the surface hardness can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for coating wood fiberboard that forms a coating film on the surface without discoloration.

(Conventional technology and its problems) Wood fiberboards, especially soft fiberboards that are lightweight and have excellent insulation properties, are often formed by wet papermaking, and in this case, white water in papermaking JS 9 is repeatedly used. When continuously produced,
Wood components such as ligniji and hesan710-su extracted into the white water increase in concentration and adhere to the front and back surfaces of the wood fiberboard. When a linear or granular coating is applied, the above-mentioned lignidge is easily eluted by hot water when the paint dries, so it is eluted into the moisture in the paint, causing yellowing of the paint and deterioration of its cosmetic properties.

In order to eliminate such yellowing of the paint film, the surface of the wood fiberboard can be removed by cutting the surface of the wood fiberboard before painting to remove the lysine component attached to the surface of the fiberboard, but cutting equipment, S collection equipment, etc. There is a problem that a separate equipment is required, which increases the equipment cost.

On the other hand, it is well known that wood and pulp are bleached, but conventional techniques generally involve bleaching at a temperature of 100°C or less for a long period of time to bleach the wood or pulp itself and increase whitening. Yes, if this method is used for raw fiber,
It is conceivable to dry again and paint after a very long bleaching process, but unlike wood boards such as veneer, wood fiberboard swells in the bleaching solution and loses its strength, making it difficult to handle and re-drying. This required a large number of energy sources, resulting in high costs.

(Purpose of the Invention) The present invention has been made in view of the above-mentioned problems, and aims to decompose the wood components in the wood fiberboard formed by the wet papermaking method, especially the colored components in the snails that adhere to the fiberboard surface. The present invention also provides a method for painting wood fiberboard that can stably form a coating film without discoloration.

(Structure of the Invention) In order to achieve the above object, the method for painting a wood fiberboard of the present invention involves bleaching the surface of the wood fiberboard and then painting the surface with a water-based paint.

The bleaching agent to be applied to the surface of the wood fiberboard is 1. For example, add sodium hydroxide, silicate sorter, etc. as an alkaline agent to hydrogen peroxide bleach to adjust the pH to 8 to 11, preferably 9.
A liquid agent adjusted to 11 to 11, a peroxide sorter, a hypochlorous acid sorter, chlorine dioxide, etc. are used.

In addition, when hydrogen peroxide, which is highly reactive, is used as a bleaching agent, it is desirable to add magnesium hydroxide or the like to the hydrogen peroxide bleaching agent in order to prevent decomposition of hydrogen peroxide during storage.

After the hydrogen peroxide bleaching agent whose pH has been adjusted in this manner is applied to the surface of the wood fiberboard obtained by wet papermaking, the surface to which the bleaching solution has been applied is immediately heat-treated using a heated oven or a heating plate. In this case, heat treatment is performed on the coated surface using a heat treatment solution heated to 800 to 500 degrees Celsius, and the humidity accelerates the decomposition rate of the hydrogen peroxide bleach, allowing the surface layer of the wood fiberboard to adhere to the surface layer. It decomposes the coloring components in the snail in a short time to achieve a good bleaching effect, and it also suppresses the fuzz of the wood fibers on the surface of the fiberboard and smooths it.

The surface of the wood fiberboard thus bleached is then coated with a water-based paint, which is then dried to form a paint film.

In addition, by performing the surface treatment of the wood fiberboard using the heat oven or hot plate, it is possible to effectively bleach the fibers and at the same time eliminate the fuzz of the fibers, thereby creating a good painted surface with no color spots and good adhesion of paint. Moreover, it is possible to harden the fiberboard surface and improve the surface hardness.

Next, specific examples of the present invention will be shown.

(Explanation of Examples) 609 on the surface of wood fiberboard formed by wet papermaking
A bleaching agent having the following composition and having a pH adjusted to 9.6 was applied at a ratio of /d.

Bleach composition concentration 35g6 Hydrogen peroxide 100 parts by weight'504
NaOH8# #40%NazSiOs 3' water
8941 Next, the bleach-applied surface was heat-treated with a hot oil heated to 400°C to decompose hydrogen peroxide and bleach wood components such as resin on the surface of the wood fiberboard.

Thereafter, a white paint made by mixing vinegar and emulsion with calcium carbonate was applied in granular form to the surface of the wood fiberboard by a known method such as a roll or spray.

The coating may be applied uniformly over the entire surface of the wood fiberboard or may be applied partially in granular form, and the selection may be made depending on the intended use of the decorative board.

(Effects of the Invention) As described above, according to the method for coating wood fiberboard of the present invention,
After bleaching the surface of the wood fiberboard, the surface of the wood fiberboard is painted with water-based paint, which decomposes the wood components, especially the coloring components of the resin, which may cause yellowing or browning due to staining. It is possible to obtain a stable coating film that eliminates discoloration.

In addition, by subjecting the surface of the bleaching agent applied to the wood fiberboard to heat and pressure treatment using a heated 0-l, etc., the bleaching agent can be decomposed in a short period of time, making it possible to achieve good bleaching and also eliminate the fuzziness of the fibers. It can form a beautiful painted surface.

Furthermore, since only the surface layer of the wood fiberboard is bleached, there is no decrease in the strength of the fiberboard, and when bleaching is performed in conjunction with heat-pressure treatment, the surface hardness of the fiberboard can be improved. has.

Claims (2)

[Claims] (1) A method for painting a wood fiberboard, which comprises bleaching the surface of the wood fiberboard and then painting the surface with a water-based paint. (2) The method for painting a wood fiberboard according to claim 1, which comprises applying a bleaching solution to the surface of the wood fiberboard and then bleaching the surface by heat-pressure treatment.