JPS595678B2 - Pattern coloring method for aluminum or aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a series of unique treatment steps including electrolytic coloring twice before and after to treat aluminum or aluminum alloy (hereinafter simply referred to as aluminum).
The present invention relates to a method of obtaining a colored film with a clear pattern in two colors without using dyes or pigments on the surface of the film.

Conventionally, methods for patterning aluminum include (2) patterning the aluminum surface with a resist material and anodizing it, then removing this resist material, and then
A method of exposing colored patterns through electrolytic coloring.

(Japanese Patent Publication No. 53-39006) (B) After forming a porous anodic oxide film on the surface of aluminum, first print using dye ink, then further print coating on the surface using pigment ink. How to do it.

(Japanese Patent Publication No. 55-21117) (q A method of electrolytic coloring by forming a porous anodic oxide film on the surface of aluminum and then printing a desired pattern on the oxide film surface with a substance that has a masking effect. .

(Japanese Patent Publication No. 55-9960) is known.

However, method M requires a troublesome process of removing the resist material used for patterning with an organic solvent such as trichlene between the anodizing process and the electrolytic coloring process. , the work process is complicated and the number of man-hours increases, and the dye ink's weather resistance is a weak point, and if the pigment ink print peels off, there is a risk of the pattern disappearing. In this method, since the pattern is colored in one color instead of multiple colors, the pattern cannot be avoided from being monotonous.

The present invention was developed in order to solve the drawbacks of the conventional method, and involves first applying an anodic oxidation coating to the aluminum to be treated, then immersing it in a solution containing a metal salt. Next, electrolytic coloring treatment is performed, and then a transparent resin having electrical insulation properties is coated or printed on the surface of the anodic oxide film after coloring to mask it into a desired pattern. The non-masked areas are decolorized by immersion in a bath containing or electrolytically treated in the bath, and then subjected to a second electrolytic coloring bath in an electrolytic coloring bath having a composition different from the first electrolytic coloring bath. After carrying out a coloring treatment to obtain a two-color patterned colored film on the surface of the object to be treated, the surface is further coated with a protective coating with a paint that has good adhesion to the transparent resin having electrical insulation properties. It is something to do. To explain the method of the present invention in more detail, there are no particular restrictions on the initial anodic oxide film treatment.
An anodic oxide film is formed on the surface of the object to be treated by electrolytic treatment using direct current or alternating current in an aqueous solution containing a conventionally known inorganic acid or organic acid such as sulfuric acid or oxalic acid as a main component.

The next primary electrolytic coloring bath contains nickel, cobalt, chromium, copper, cadmium, selenium,
Electrolytic coloring is performed using methods such as direct current cathode electrolysis or alternating current electrolysis using an electrolytic solution containing salts of metals such as manganese, molybdenum, vanadium, silver, tin, and lead, to uniformly color the entire surface of the object to be treated. . Next, when coloring a pattern, a desired pattern is formed by coating or printing a transparent resin having electrical insulation properties such as acrylic-melamine resin paint on the anodic oxide film surface of the object to be treated after the first electrocoloring. After masking, only the non-masked areas are decolorized by immersion in a bath containing inorganic acids, organic acids, or their salts, or by electrolytic treatment in the bath, and then A secondary electrolytic coloring treatment is performed to obtain a different color tone by immersing it in an electrolytic coloring bath having a composition different from that of the electrolytic coloring bath.

When such a treatment is applied, the areas masked with the transparent resin are not electrolytically colored at all, and the color of the primary electrolytic coloring is directly visible through the X transparent film, and the areas that were not masked with the transparent resin are not electrolytically colored. The second electrolytic coloring will be performed only on the second electrolytic coloring process, but the coloring of the non-masked areas will be done by the decoloring process that is performed before the second electrolytic coloring process.
Since the color of the secondary electrolytic coloring process has been bleached, the color applied in the secondary electrolytic coloring process clearly appears in the non-masked areas, so there is a strong contrast with the color of the primary electrolytic coloring process, and A two-color patterned film with clear and vivid colors can be obtained on the surface of objects. Finally, a protective coating is applied to the surface of the object having the patterned colored film using a paint that is the same as or has good adhesion to the electrically insulating transparent resin used for masking. Complete the pattern coloring process. In the above case, the electrically insulating transparent resin that is masked on the surface of the object to be treated prior to the secondary electrolytic coloring treatment is an electrically insulating resin that is sufficient to prevent decolorization and electrolytic coloring of the anodic oxide film surface. It is meant to be a transparent film material that has a high degree of properties and allows the colored film of the primary electrolytically colored part to be seen through from the outside, and does not require a very large electrical resistance.

In addition, as a specific method for printing the transparent resin on the anodic oxide film surface after the first electrolytic coloring, any printing method such as letterpress, lithography, intaglio, or screen printing can be used by adjusting the type and viscosity of the solvent. Available for use. Furthermore, if drying is performed after the pattern masking process, floating and mixing of the solvent and resin into the decolorizing bath and the secondary electrolytic coloring bath can be prevented.
On the other hand, for the paint to be applied as a protective coating on the patterned colored film surface after the completion of the secondary electrolytic coloring, in order to stabilize the film, the same type of paint as the transparent resin used in the pattern masking process may be used. Or even if it is not the same, it was applied before,
A paint with good adhesion to the masking material is used, and any method conventionally used for painting aluminum can be used.

Further, particularly when an electrodeposition coating method is used as a coating method, pattern masking also exerts a masking effect in this coating process, making it possible to obtain a coating film with an unprecedented uneven surface. As described above, if the method of the present invention is applied to pattern coloring of aluminum, the masking material removal step at the time of pattern coloring is not necessary, so a desired pattern colored film divided into two colors can be obtained by a relatively simple coloring process. Furthermore, the patterned color formed on the surface of the treated object is produced by electrolytic coloring, unlike those colored using dyes or pigments, so the color does not fade easily and is weather resistant. Excellent and
Further, in the case of the present invention, the coloring of the pattern by the secondary electrolytic coloring is such that the color of the primary electrolytic coloring is erased by a decoloring treatment of the non-masking area that is performed prior to the electrolytic coloring.

The two colors colored in the subsequent electrolytic coloring process rarely overlap, and the color colored in the second electrolytic coloring process clearly appears in the non-masking area, so it is difficult to color the non-masked areas in the first electrolytic coloring process. A two-color patterned coating with a strong contrast with the applied color and a clear and vivid coloring effect is obtained on the surface of the treated object.Furthermore, the protective coating applied to the patterned colored coating surface is coated with masking material. Because we use a paint that has good adhesion to the paint, there is no fear that the paint film will peel off easily, and the underlying patterned color film will be reliably retained and its beautiful color tone will remain stable for a long time. It is something that can be kept. Examples of the present invention are listed below, but the present invention is not necessarily limited to these examples.

Example 1 An aluminum alloy plate (6063S) was pretreated by a conventional method and heated in a 180y/' sulfuric acid bath at a bath temperature of 20°C and a current density of 1.
．． After anodizing for 30 minutes at 0A/d,
Using a primary electrolytic coloring bath with the following conditions, electrolysis was performed for 50 seconds at DC 12 using the above sample as a cathode, and a uniformly colored film with a bronze color was obtained. After drying this sample to remove surface water, a trichlorethylene solvent-based acrylic-melamine resin with a solid content of 35% was printed in a wood grain pattern on the sample by lithographic printing, and then dried. When the sample was immersed in a 200 r/l nitric acid bath for 10 minutes, the bronze color in the non-masked area was bleached.

Then, a second electrolytic coloring bath electrolysis was carried out under the following conditions, and a wood grain pattern was obtained in which the resin-masked areas were bronze-colored and the non-masked areas were cold-colored.

Next, after drying the sample to remove surface moisture, the bath temperature was 8
After immersion for 10 minutes in a trichlorethylene solvent-based acrylic-melamine resin paint bath at 0°C and 20% solids, 1.
When it was pulled up at a speed of 5 m/min and baked at a temperature of 190° C. for 30 minutes, a colored film with a beautiful wood grain pattern with a uniform coating surface was obtained.

Example 2 An aluminum alloy plate (6063S) was pretreated by a conventional method and heated in a 1507/l sulfuric acid bath at a bath temperature of 20°C and a current density of 1.
．． After anodic oxidation for 30 minutes under the conditions of 2 A/d, electrolysis was performed for 2 minutes at 12 V DC using the above sample as a cathode using the primary electrolytic coloring bath under the following conditions, and a uniform brown colored film was obtained. It was done.

Next, this sample was dried at a temperature of 100°C for 10 minutes to remove surface moisture, and then an acrylic film containing 25% solids was dried.
A melamine resin paint (Shinto Toyo Super Glimin) was screen printed on the sample in a wood grain pattern, dried, and then placed in a 1007/l sulfuric acid bath with the sample as the anode and heated at 18 V DC. When electrolytically treated for 2 minutes, the brown color of the non-masked area was decolored.

Next, electrolysis was carried out at 12 V AC for 1 minute using a secondary electrolytic coloring bath with the conditions described in J. The resin masking area was brown and the non-masking area was pale red. After drying the sample to remove surface moisture. , 15% solids acrylic-melamine resin paint (Shinto Paint Super Grimin A)
When spray painting was performed using L) and baking at a temperature of 130° C. for 25 minutes, a beautiful wood grain pattern film with a uniform coating surface was obtained.

Example 3 An aluminum plate (99.2%) was pretreated by a conventional method,
In a 150 y/l sulfuric acid bath, at a bath temperature of 20°C and a current density of 2.
After anodizing for 20 minutes under the conditions of 0 A/Dm'', a first electrolytic coloring bath acrylic-melamine resin under the following conditions was printed in a wood grain pattern on the sample using letterpress printing, and then dried.

Thereafter, the sample was electrolytically treated in a 50 y/l oxalic acid bath at 15 V DC for 2 minutes using the sample as an anode, and the bronze color of the non-masked area was decolored. Next, electrolysis was carried out at 30 V AC for 2 minutes using a secondary electrolytic coloring bath under the following conditions, and a pattern was obtained in which the resin masking areas were bronze-colored and the non-masking areas were cold-colored.

Next, the sample was immersed for 2 minutes in a water-soluble acrylic-melamine electrodeposition paint bath with a bath temperature of 23°C and a solid content of 10%, and then
Perform anodic electrolysis at 50V for 2 minutes and at a temperature of 190℃ for 3 minutes.
When baked for 0 minutes, a beautiful wood grain pattern film with an uneven coating surface was obtained.

Claims (1)

[Claims] 1 After the aluminum or aluminum alloy to be treated is previously subjected to anodic oxide film treatment, it is immersed in a solution containing a metal salt to perform a primary electrolytic coloring treatment, and then the surface of the anodic oxide film after coloring is applied. Masking the desired pattern by coating or printing a transparent resin with electrical insulation properties,
Thereafter, the non-masked areas are decolored by being immersed in a bath containing an inorganic acid, an organic acid, or a salt thereof, or electrolytically treated in the bath, and then treated with the first electrolytic coloring bath. After performing a secondary electrolytic coloring treatment in electrolytic coloring baths of different compositions to obtain a two-color patterned colored film on the surface of the treated object, the adhesiveness of the surface to the transparent resin having electrical insulation properties is further improved. A pattern coloring method for aluminum or aluminum alloy, which is characterized by applying a protective coating using a paint with good quality.