JPS647160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coloring an electrocoated film that gives the electrocoated film a bright gold tone.

Conventionally, transparent, translucent, or colored electrodeposited films have been formed on the surfaces of light metals, etc., as so-called top coats for the purpose of protecting the base material and improving aesthetics. As a method for imparting a gold tone, a method has been adopted in which a pigment or dye that imparts a gold color is mixed into an electrodeposition paint, and this paint is used to electrodeposit an electrodeposition coating film having a gold tone.

However, this method uses an electrodeposition paint bath containing pigments or dyes, but it is difficult to control the content of pigments and dyes in the paint bath, and bath management is troublesome. Only the same gold color can be obtained from the same bath, so if different gold tones are required, there is the inconvenience that separate paint baths with different bath compositions must be prepared and used. Furthermore, since such a method for coloring an electrodeposition coating film uses a bath containing a mixture of pigments and dyes, there is a problem that the color tone tends to be uneven.

In view of the above circumstances, the inventors of the present invention have conducted intensive studies on a coloring method for imparting a gold tone to the electrodeposited film. After forming a colorless, transparent or translucent electrodeposited film using an electrocoating paint bath that does not contain pigments, this film is subjected to heat treatment at a higher temperature and/or for a longer period of time than when performing normal baking drying. When the electrodeposited coating is heat-treated until it turns yellow, the transparent or translucent yellowing electrodeposition coating and the metal color of the underlying metal object that can be seen through the coating mix,
In addition to obtaining vivid coloring, by varying the degree of yellowing of the electrodeposited film by changing the heat treatment conditions, various gold tones can be created, from yellowish gold to reddish gold. The inventors discovered that a colored film having the above-mentioned properties can be easily obtained, leading to the present invention.

That is, in the method of the present invention, it is thought that it is necessary to avoid heat treatment that causes the conventional transparent or semitransparent coating film formed as a top coat to turn yellow and burn. It is common knowledge that heat treatment should be carried out so as not to change the color tone of the object, but we went against the norm and changed the color of the transparent or semi-transparent coating to yellow by heat treatment, which contrasts this yellow color with the silvery white color of the object to be treated. It gives a gold tone to the paint film by combining with.

The present invention will be explained in detail below.

The method for coloring an electrocoated film according to the present invention is to apply a colorless, transparent or translucent electrocoated film to a workpiece having a silvery-white metallic luster surface using an electrocoated paint bath that does not contain pigments. After being formed, this film is heat treated until it turns yellow.

Here, the material of the object to be colored may be any material that can be electrodeposited, and is not necessarily limited, but metal materials such as steel or conductive plastic materials such as ABS resin are recommended. Those that have been subjected to plating to form a plating film are preferably used, and aluminum, aluminum alloy materials, and the like are also suitably used. In this case, the surface of the object to be treated has a silvery white metallic luster, and by applying the method of the present invention to this metallic lustrous surface, very vivid coloring can be obtained. Therefore, when forming a plating film, it is recommended to add a brightener to the plating bath to form a bright plating film. The plating film may be formed by an electroplating method or an electroless plating method.As a plating film, nickel, chromium, zinc, etc. A plating film that gives a bright silvery white metallic luster is suitable.

In the present invention, a colorless, transparent or translucent electrodeposition coating film is formed on the surface of the object to be treated using an electrodeposition paint bath that does not contain a pigment. in this case,
As the electrodeposition paint that provides such an electrodeposition film, known paints that provide a transparent or translucent paint film, such as epoxy resin-based and acrylic resin-based paints, can be used, but epoxy resin-based paints are particularly preferably used. By using this type of material, beautiful coloring can be obtained.

Electrodeposition coating may be either cationic electrodeposition coating or anionic electrodeposition coating, but in order to avoid metal elution and provide a beautiful coating film, anionic electrodeposition coating method in which the object to be treated is used as a cathode is preferable. It is preferable to adopt it. However, for aluminum and aluminum alloy materials, a cationic electrodeposition coating method can be suitably employed.

The conditions for electrodeposition coating are not particularly limited, and known conditions such as bath voltage of 50 to 150 V and current application time of 1 to 2 minutes are adopted, and the coating film usually has a temperature of 5 to 150 V.
Formed to a thickness of 20 μm.

Next, after the electrodeposition coating film is formed, heat treatment is performed in the present invention to yellow the film. in this case,
The heat treatment may be performed by separately baking and drying the film after forming the electrodeposition coating film, but it is easier to perform the heat treatment when the film is baked and dried. It is preferable because

The conditions for the heat treatment are those that can cause the electrodeposition coating to turn yellow, and the heat treatment conditions are higher than those for normal baking drying or for a longer period of time. Specifically, the heat treatment conditions vary depending on the type of resin used in the electrodeposited coating, but for example, in the case of epoxy-based clear resin paint, heat treatment conditions of 200 to 220°C and 25 to 35 minutes can be used to meet the required voltage. Heat treatment conditions are appropriately selected depending on the degree of yellowing of the painted film.

In this way, by yellowing the electrocoated coating, the yellowed transparent or translucent electrocoating coating and the metallic color of the surface of the object to be treated, which can be seen through it, are effectively fused, A transparent and beautiful gold color tone can be obtained, and in this case, by varying the degree of yellowing of the electrodeposited film, various gold color tones with different shading can be formed.

According to the present invention, it is not necessary to use a bath containing pigments or dyes as an electrodeposition paint bath, so the management of the electrodeposition paint bath is easy, and when forming gold colored films of different colors, heat treatment conditions It is not necessary to change the composition of the electrodeposition coating bath. Even when forming colored films with different tones, a bath having the same composition can be used and the same coating conditions can be used to form the electrodeposition coating film. Furthermore, since the method of the present invention does not use pigments or dyes, there is no unevenness in color tone and a stable color tone can be obtained. Therefore, by employing the present invention, it is possible to easily and reliably apply gold coloring with a rich variety of bright tones.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the present invention is not limited to the following examples.

[Example 1] Using an epoxy cationic clear electrodeposition coating bath (nonvolatile content 10%), a glossy nickel plating film was formed on a stainless steel plate as an anode and a steel plate as a cathode to be treated by a known method. Using each of the
The treatment was carried out for several minutes to form an electrodeposition coating film on the object to be treated.

Next, this film is baked and dried at 200°C.
Heat treatment was performed for 25 minutes to yellow the electrodeposited coating. As a result, a bright gold-toned film was obtained on the underlying glossy nickel plating film.

[Example 2] A steel plate on which a bright nickel plating film was formed and a chromium plating film of about 0.25 μm thick was further formed on the steel plate was used as the object to be treated, and electrolysis was performed in the same manner as in Example 1. A clear epoxy resin electrodeposited film was formed on the chrome plating film.

Next, this film is baked and dried at 220°C.
Heat treatment was performed for 30 minutes to yellow the electrodeposited coating. As a result, a bright gold-toned film was obtained on the underlying chrome-plated film.

Claims (1)

[Scope of Claims] 1. After forming a colorless, transparent or translucent electrodeposited film on a workpiece having a silvery white metallic luster surface using an electrocoating paint bath that does not contain pigments, this film A method for coloring an electrocoated film, characterized in that the electrocoated film is heat-treated until it turns yellow, and the yellow color of the film is combined with the silvery white color of the material to be treated, thereby imparting a gold tone to the electrocoated film. . 2. The method according to claim 1, wherein the object to be treated has a plating film formed on the surface of the material. 3. The method according to claim 1, wherein the object to be treated is aluminum or an aluminum alloy.