JPS58193394A - Formation of coating film - Google Patents

Abstract

PURPOSE:To form a coating film exhibiting japanned apearance, while forming a thick coating film even at the corner of an Al material, by electrophoresis coating said Al material and then dip coating it using paint having a different color. CONSTITUTION:A colored or uncolored anodically-oxidized or chemically-converted film is previously formed on the surface of an Al article. This Al article is electrophoresis coated using transparent resin paint or the like. Thereafter, it is washed with water, optionally dried by heat and then dip coated using paint having a color different from that of the coating film formed by the electrophoresis. By this method, a coating film having sufficient durability and exhibiting japanned appearance is obtained even at the corner of the workpiece to be coated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a lacquer-like coating on the surface of an aluminum material.

The immersion coating method, in which the object to be coated is immersed in a paint tank and then pulled up to adhere a paint film, produces different coating thicknesses depending on the shape of the surface to be coated, the physical properties of the paint, and the speed at which the object is pulled up from the paint tank. give.

When dip-coating is applied to an aluminum material, the thickness of the coating film formed differs between the flat part and the corner part of the aluminum material, being thicker in the flat part and thinner in the corner part.

Utilizing the above-mentioned characteristics of the dip-painted coating, the color tone of some corners of the urushi-lacquered style (hereinafter simply referred to as lacquer-lacquered style) is created by scraping out to partially reveal a different colored base coat. A method for attaching a beautiful coating film to aluminum materials that is different from that on flat areas is well known, and is used in part as a coating method for various aluminum products such as aluminum building materials used for sliding doors, doorbells, partitions, etc., showcases, picture frames, Buddhist altars, etc. It has been put into practical use.

However, this painting method is based on the principle that the above-mentioned decorative effect is produced by the fact that the coating film is thin in some corners so that the background color of the aluminum material is visible only in these areas. The disadvantage is that the coating film performance, such as corrosion resistance and abrasion resistance, is poor.

In many applications, parts of the corners (flat parts) are subject to much more friction and impact, and the paint film is more likely to be damaged, so the paint and film performance at the critical corner parts is poor. This is a fatal flaw in this type of decorative coating.

The present invention provides a method that does not have the disadvantages of the conventional method of forming a lacquer-lacquered film by dipping, and can form a beautiful lacquer-lacquered film while forming a sufficiently thick coating even on some corners. The purpose is to provide

The present invention, which has succeeded in achieving the above object, involves first applying electrophoretic coating to an aluminum material, and then applying dip coating using a paint that provides a coating film with a color different from that of the electrophoretic coating. This is a characteristic feature.

Electrophoretic painting is a method in which a potential difference is applied between the object to be coated and a counter electrode in a paint tank, causing paint particles to electrophores toward the object and then coagulating and precipitating on the surface of the object to form a coating film. Therefore, a uniform coating film can be obtained regardless of the shape of the surface of the object to be coated, and a coating film that is thicker tends to be formed on corners rather than on flat areas.

Therefore, if you use this method to apply a sufficiently thick paint film to some corners, and then apply a paint film with a color different from the color of the electrophoretic paint film by dip painting. , the electrophoretic coating or the surface of the aluminum material (if transparent paint is used for the electrophoretic coating) can be seen through the thin dip-coated coating on only a portion of the corner, creating a lacquer-like appearance. A sufficient coating film can also be obtained for partial protection.

The actual coating method of the present invention will be explained in detail below.

The aluminum material to be coated by the method of the present invention can be coated with a colored or uncolored anodic oxide film or chemical conversion film (so-called boehmite treatment, chromate treatment or phosphate treatment) on its surface,
It is desirable to improve the adhesion of the paint. The anodized film may be relatively thin. When the surface film is a colored film and the electrophoretic coating film is made transparent, the color of the background of the aluminum material is used to create a lacquered effect. Select by considering the harmony with the color tone. Coloring may be done by any method such as natural coloring, electrolytic coloring, and dyeing.

Electrophoretic painting is performed using a conventional method. In other words, there is no problem with either anionic electrodeposition using an anionic electrodeposition paint with the object being coated as an anode, or cationic electrodeposition using a cationic electrodeposition paint with the object being coated as a cathode, and depending on the type and concentration of the paint. , pH1 temperature, applied voltage, and the like are not required.

However, as mentioned above, apply lacquer to the background color of the aluminum material.

It must be The thickness of the electrodeposition coating is 5 to 30
Approximately μ is appropriate.

After the electrodeposition process of electrophoretic coating is completed, after washing with water and heating and drying, perform the next dip coating, or immediately dip coat on the semi-dry coating without heating and drying. . In order to improve the adhesion between two paint films, when heat drying is performed, the paint should be selected so that the main film forming elements of the dip coating paint are the same or similar to those of the electrodeposition paint, for example. (If you are using an acrylic-melamine electrocoating paint, use the same acrylic dip paint.) If heat drying is not used, the solvent of the dip paint is compatible with that of the electrocoat paint. It is desirable to select a paint so that

Other than the points in Section L, dip coating does not require any special conditions, and each step of dipping, pulling, and drying (or baking) is similar to the conventional lacquer-like coating. It can be done in the same way as for dip coating.

According to the method of the present invention as described above, it is possible to obtain a beautiful lacquer-like coating film having sufficient durability even on some corners of the object to be coated. A particular advantage of the method of the present invention is that by selecting the color of the background of the aluminum material (the color of the colored film) and the combination of the colors of the two coatings, it is possible to create depths that are not possible with conventional methods. The present invention will now be explained by way of examples, which provide certain color tones and excellent decorative effects.

Example 1 An extruded aluminum profile (A 6063 S-T, .) was subjected to the usual pretreatment and then treated with sulfuric acid at 150 g/l at 20°C.
anodized for 30 minutes at a current density of 1.2 A/dm2 using a bath of
The sample was immersed in an ε bath at 50° C. for 10 minutes, and the oxide film was colored gold.

After treatment, the aluminum material is coated with transparent resin paint PM-300.
0 (product of Nippon Paint Co., Ltd.) immersed in a 20°C water bath containing 10%, and heated to 150 cm DC using the aluminum material as an anode.
was applied for 3 minutes to perform electrophoretic painting. Thereafter, the aluminum material that had just been washed with water was dip-coated using a black dip-coating paint Depolon AL-E (manufactured by Takashi Kubo Paint Co., Ltd.), and finally baked at 180°C for 35 minutes.

The resulting painted product had a beautiful lacquer-like appearance with some golden yellow corners and black flat areas. The average thickness of the coating film was as follows.

Part of corner Flat area Coating film by electrophoretic coating 7μ 6μ Coating film by dip coating θ~2μ 15μ Example 2 After applying normal pretreatment to aluminum extruded section (A 60635-TS), ammonia water 0, 5 v/v
%, and was immersed in a bath at 98° C. or higher for 15 minutes to perform boehmite treatment.

After treatment, the aluminum material is coated with white resin paint PM-600.
0 (product of Nippon Paint Co., Ltd.) at 20° C., and electrophoretic painting was performed by applying 120 μm of direct current for 3 minutes using the aluminum material as an anode. Thereafter, the aluminum material that had just been washed with water was dip-coated using a black dip-coating paint Depolon AL-E (manufactured by Toru Kubo Paint Co., Ltd.), and finally baked at 180'C for 35 minutes. The resulting painted product had a beautiful lacquer-like appearance with some white corners and black flat parts. The average thickness of the coating film was as follows.

Part of corner - flat part

Claims (3)

[Claims] (1) Urushi coating style on the surface of aluminum material, characterized by applying electrophoresis coating to the aluminum material, and then applying dip coating using a paint that provides a coating film with a color different from the color of the coating film obtained by the electrophoresis coating. A method of forming a coating film. (2) The method according to claim 1, wherein the aluminum material has a colored oxide film or a colored chemical conversion film. (3) The method according to claim 1, in which electrophoretic painting is performed using a transparent resin paint.