JPH0445866A - Method for coating woody decorative laminate - Google Patents

Abstract

PURPOSE:To well satisfactorily coat a woody decorative laminate by an electrostatic coating method by laminating an electrically conductive sheet on a woody material as a base material and carrying out electrostatic coating. CONSTITUTION:An electrically conductive sheet, e.g., formed by adding a proper amt. of an electrically conductive material such as graphite to thermoplastic resin and shaping them into a sheet is laminated on a woody material as a base material by adhesion with an adhesive or other method and electrostatic coating is carried out. The resulting woody decorative laminate can be well satisfactorily coated by the electrostatic coating method not fit to coat the woody material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for applying electrostatic coating to a wood decorative board.

[Prior Art] Coating means using an electrostatic coating method has conventionally been widely used as a means for coating single metal feathers. however,
As a means of coating wood or wood products, conventional spraying is only rarely used.

[Technical problem to be solved by the invention 1] Painting using electrostatic painting method saves the amount of paint compared to normal spray painting and improves productivity.
Furthermore, it has been widely used for metal materials because it enables coatings with a stable and uniform thickness to be obtained.

However, to date, electrostatic coating has not been applied satisfactorily to products such as decorative boards that are made of wood or as a base material. The reason for this is that, as shown in Table 1, wood materials have an extremely high electrical volume resistivity compared to metal materials, and the resistivity fluctuates depending on the drying state.
1) Characteristics 2) Due to the fact that the moisture content may differ in some areas or be normal, even if the coating is applied by electrostatic coating, the coating must be thick enough to form a coating film. It is extremely difficult to obtain the required coating thickness, and various adjustments are required such as changing the applied voltage depending on the drying state of the wood, and even if the required coating thickness is obtained, the thickness The surface had to be uneven and uneven.

This means that the characteristics of electrostatic coating itself, which are uniform coating thickness and good coating condition, cannot be fully utilized.

The present invention makes it possible to use the electrostatic coating method, which has not been able to be used satisfactorily as a coating method for wood materials, in a fully satisfactory manner as a coating method for wood decorative boards. It is intended to be.

Table 1 Electrical volume resistivity of wood (Ω・cm) Wood bone dry (moisture content 096) 10” to 1o16
Air dry (moisture content 12-15%) 10'-1o9
Fiber saturation point (moisture content approximately 30%) 1o6 (It is obvious that wood materials at the fiber saturation point cannot be used as materials for decorative laminates) [Means for solving the problem] The purpose of solving the above problems In order to achieve this, the present invention disposes a conductive sheet-like body on a base material of wood interest, and then applies electrostatic coating to 1 q of the wood base material. I decided to paint it.

The wooden base material is not particularly limited, and may be ordinary particle board, medium density fiberboard (MDF), or veneer.

Is it possible to use various types of conductive Sea I binding?
A sheet made by adding an appropriate amount of a conductive substance such as metal powder, carbon black, graphite, or carbon fiber to a thermoplastic resin, or a conductive material made by adding conductive fibers such as carbon fiber or metal fiber during papermaking. Paper, conductive impregnated paper obtained by impregnating paper with melamine DAP resin or the like to which the above-mentioned conductive substance is added, and conductive polymer resin sheets in which the resin itself is conductive are effective. An example of the electrical volume resistivity of the sheet No. 1 is as follows.

Melamine Datsura conductive impregnated paper 105~1O7Ω'cm Appropriate means can be used to arrange the conductive sheet on the wood base material, such as bonding with adhesive, vacuum press, Alternatively, a method such as a laminate press is effective.

As the electrostatic coating means, conventionally known ones can be used as they are.

In addition, if necessary, appropriate post-coating is applied to the electrostatically coated product to create a decorative board.

[Example] The following decorative boards A, B, and C were prepared and electrostatically coated. In each case, a decorative board without conductivity was also prepared and electrostatically coated in the same manner. The thickness of the coating film was measured in each case. The results are shown in Table 2.

A. Conductive repaintable urethane coated paper (30
g/m2.10"Ωcm) was laminated and pressed on both sides of a 18mm thick particle board with an adhesive (vinyl acetate).The pressing conditions were: 130°C, I Okg/m
cm2 for 1 minute.

B, conductive melamine-impregnated paper (100g/+n2
．． +06Ω·cm) was hot-pressed on both sides of a particle board with a thickness of 18mm. Heat and pressure conditions are 180°C, 25k
g/c for 1 minute.

A repaintable vinyl chloride sheet with C1 conductivity (thickness 200μ, 107Ω・cm) was vacuum pressed onto a 18mm thick medium density fiberboard (MDF) shaped using a router using a vinyl acetate adhesive. did.

As a comparative example, sheets with no conductivity or with the same other conditions were prepared, and decorative laminates A', B', and C' bonded to the respective base materials were prepared.

Next, unsaturated polyester Zandink sealer was applied to each coat using an air atomization type electrostatic coating machine at a voltage of 90.
Painting was performed at kV. The composition of the paint is as follows.

Unsaturated ester sanding roller - 100 parts by weight 6% cobalt naphthenate o, 6 methyl ethyl ketone bar side l
[Styrene 20] The air pressure was 5 kg/ct, and the discharge rate was 150 cc/min.

After painting, it was left at 35°C for 30 minutes, and then cured for 20 minutes in a far-infrared dryer to obtain a painted decorative board.

For decorative laminates A, B, and C, whether a coating film with an almost uniform thickness was obtained over the entire surface with no irregularities, and for decorative laminates A', B', and C', the coating film or, especially, the hanger attachment. The film thickness was thick in the vicinity of A, and the film thickness in other parts was thin and non-uniform (see Table 2).

(Margins below this page) Table 2

Claims (1)

[Claims] A method for painting decorative wood panels, which comprises disposing a conductive sheet on a wooden base material and then applying electrostatic coating.