JPH0584468A - Method for coating of fluorocarbon resin - Google Patents

Abstract

PURPOSE:To obtain a fluorocarbon resin coating film having high adhesion property with the coated surface and high corrosion resistance by first applying a liquid coating material of fluorocarbon resin on a roughened surface of a body to be treated, and then applying a powder coating material of fluorocarbon resin thereon. CONSTITUTION:The surface 11 to be coated of an aluminum plate or the like is degreased with acetone or the like and dipped in a sodium hydroxide soln. to remove an oxide film and then etched with an etching device. After the sheet is cleaned and dried, a liquid coating material of PFA is applied on the surface 11 by spin coating, etc., and dried and calcined. Then a powder coating material of PFA is applied thereon by an electrostatic coating method that electric potential is applied between the coating side and the surface to be coated to adsorb the powder on the surface to be coated. Thereby, the fluorocarbon resin coating film having high corrosion resistance can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin coating method for coating cookware or the like made of aluminum or aluminum alloy in order to reduce tackiness.

[0002]

2. Description of the Related Art Fluororesin paints include liquid paints and powder paints. When applying liquid paints to the inner surface of cooking utensils made of aluminum or aluminum alloy, the surface to be painted is roughened by etching in advance. A coating liquid containing a fluororesin dispersed in a solvent is applied to the surface to be coated by spin coating, spraying, dipping, etc., dried, and then baked. In the case of powder coating, the surface to be coated is coated by the electrostatic coating method, dried and then baked.

[0003]

However, since the above liquid paint contains a solvent, the solvent is vaporized by drying after coating, and the density of the fluororesin itself in the coating film decreases after drying. Therefore, there is a problem that the coating film after firing becomes porous and poor in corrosion resistance. On the other hand, since the powder coating does not contain a solvent, the density of the fluororesin is high and a film with few pores can be formed, but the particle size of the powder coating is smaller than the diameter of the groove formed on the surface to be coated by etching. However, the paint cannot get into the groove because it is too large. Therefore, there is a problem that the adhesion to the surface to be coated is poor.

The present invention is intended to solve such problems, and an object thereof is to obtain a fluororesin coating film having high adhesion to the surface to be coated and high corrosion resistance.

[0005]

In order to solve this problem, the present invention is to form a coating film of a fluororesin liquid coating on the surface to be roughened, and to coat the fluororesin on the coating film. A coating film of powder paint is laminated.

[0006]

According to this method, first, the liquid coating material enters the groove portion of the roughened surface to be coated and comes into close contact with the surface to be coated. When the powder coating material is applied thereon, the particles of the powder coating material are filled in the pores of the coating film made of the liquid coating material. As a result, the adhesion between the surface to be coated and the coating film of the liquid coating material is high, the pores of the coating film of the liquid coating material are filled with the particles of the powder coating material, and a fluororesin coating film having high corrosion resistance can be formed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an aluminum plate, 2 is a coating layer formed by a liquid coating of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA) provided on the surface of the aluminum plate 1, and 3 is this coating. It is a coating layer made of PFA powder coating formed on the surface of the membrane layer 2.

Next, a method for producing a fluororesin coating film will be described with reference to FIG. In FIG. 2, 11 is two aluminum plates, 12 is an alternating current source connecting the two aluminum plates 11 and 11, and 13 is a 5 wt% sodium chloride solution. First, the aluminum plate 11 is degreased with acetone. Next, the aluminum plate 11 is immersed in a 10 wt% sodium hydroxide solution to remove the oxide film on the aluminum plate 11. afterwards,
Using the etching apparatus shown in FIG. 2, an AC power source is energized to etch the surface of the aluminum plate 11. After etching, ultrasonic cleaning is performed. Dry aluminum plate 11
Liquid paint of PFA is applied to the surface by spin coating method at 5-10 μm
Paint, dry, and bake. This forms a coating layer of PFA liquid paint. Next, by applying an electric potential difference between the coating side and the surface to be coated, the powder coating of PFA is applied over the coating layer of liquid coating by 20 to 30 μm by electrostatic coating method in which powder is attracted to the surface to be coated. To do. As a result, a coating layer of PFA powder coating is formed.

As described above, according to this embodiment, by using the fluorine resin as PFA, a coating film having less pores can be obtained, and by using the AC etching method, the DC power source and the electrode are not required. Therefore, cost reduction can be achieved.

In this embodiment, PF is used as the fluororesin.
Although A is used, other fluororesins may be used. Further, although the etching current is AC, it may not necessarily be AC and may be DC. Although the etching solution is a 5 wt% sodium chloride solution, other etching solutions may be used. Although degreasing was performed with acetone, any organic solvent may be used as long as it is an induction solvent having a lipophilic group. Further, the 10 wt% sodium hydroxide solution for removing the oxide film may have another concentration.

[0011]

As described above, according to the present invention, when a fluororesin is applied to the surface to be roughened, first, a fluororesin liquid paint is applied, and then a fluororesin powder is applied. Adhesion to the surface to be coated is high by coating multiple layers of paint, and the powder coating of the fluororesin that forms the surface of the coating surface is a particle in the pores of the coating film of the liquid coating of the fluororesin that was previously coated. Thus, a fluororesin coating film having high corrosion resistance can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an aluminum plate having a coating layer of fluororesin according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an etching apparatus according to an embodiment of the present invention.

[Explanation of symbols] 1 aluminum plate 2 coating layer of PFA liquid coating 3 coating layer of PFA powder coating

Claims (1)

[Claims] 1. A fluorine film characterized in that a coating film made of a fluororesin liquid paint is formed on a surface to be roughened and a coating film made of a fluororesin powder paint is laminated on the coating film. Resin coating method.