JPH0452297A - Treatment for fitting colored pattern on aluminum and its alloy - Google Patents

Abstract

PURPOSE:To easily control the shape and number of a pattern for color and to obtain the desired colored pattern by forming a porous anodically-oxidized film on the surface of Al, and performing electrolytic coloring treatment on this film and then performing AC electrolytic treatment in a bath contg. alkali, metallic salt as a main body. CONSTITUTION:A porous anodically-oxidized film is formed on the surface of a base material 4 by performing anodically-oxidizing treatment for Al, or Al alloy. When the anodically-oxidized film 1 is electrolytically colored in a bath contg. the prescribed metallic salt, metal 3 based on the metallic salt in the bath is deposited to the bottom of a hole 2 and the surface of the base material 4 is colored. Then when AC electrolytic treatment is performed in the bath contg. alkali metallic salt, alkaline earth metallic salt or its mixed salt as a main body, eluting reaction of metal 3 is caused in the anode part. Further metal 3 is eluted from the hole 2 by gaseous hydrogen generated in a cathode part. In other words, the eluted part is decolored. The shape of this decolored part depends on a method for holding the base material 4 in the bath. Therefore the shape and number of the pattern for color are easily controlled and the desired colored pattern is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a treatment method for applying a colored pattern to the surface of aluminum and its alloys.

(Prior Art) Conventionally known methods of coloring and patterning aluminum and its alloys include, for example, first creating needle-like, streak-like, etc. patterns on the surface of aluminum or its alloys by electrolytic etching using alternating current. There is a method in which a pattern is obtained by forming an etched area, and then anodization treatment and electrolytic coloring treatment are performed to make the etched area dark and the unetched area bright (for example, JP-A-53-8335.5B -11
847, 55-47396).

(Problems to be Solved by the Invention) However, in the above method, since the coloring process is performed after patterning, it is not possible to control the balance between the shape, number, etc. of the pattern and color.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for coloring and patterning aluminum and its alloys, which allows a desired color pattern to be obtained by easily controlling the shape, number, etc. of the color pattern.

(Means for Solving the Problems) The method of coloring and patterning aluminum and its alloys of the present invention involves forming a porous anodic oxide film on the surface of aluminum or its alloys by anodizing treatment, and forming a porous anodic oxide film on the surface of aluminum or its alloys. Electrolytic coloring treatment is applied to the anodic oxide film in a bath containing salt,
Next, AC electrolysis treatment was performed in a bath containing mainly an alkali metal salt, an alkaline earth metal salt, or a mixed salt thereof, so that the precipitated metal in the pores of the anodic oxide film was partially eluted by the generated gas. Furthermore, an inorganic acid or an organic acid is added to the bath in which AC electrolytic treatment is performed, and the anode previously formed is further treated as an anodic oxide film by twice anodic oxidation treatment. This uses an oxide film whose pore size has been enlarged.

The anodizing treatment is performed by a conventional method. That is, for example, in a bath of an inorganic acid such as sulfuric acid, phosphoric acid, chromic acid, or an organic acid such as oxalic acid, sulfosalicylic acid, malonic acid, or an alkaline aqueous solution such as sodium hydroxide, trisodium phosphate, etc. , by electrolyzing with alternating current, pulse, PR wave, or AC/DC superposition method.

Note that after the anodizing treatment, re-anodizing treatment may be performed by electrolyzing in a bath of phosphoric acid, pyrophosphoric acid, sulfuric acid, or a mixed acid thereof in the same manner as in the above-mentioned anodizing treatment.

Electrolytic coloring treatment is also carried out by a conventional method. That is, this is carried out by applying a predetermined alternating current or direct current voltage to a bath containing a metal salt corresponding to the desired color, using carbon as a counter electrode, for example.

AC electrolytic treatment is performed as follows. That is, the electrolysis is carried out by electrolysis using an alternating current current in a bath mainly containing metal salts such as potassium, lithium, sodium, and calcium. In addition to alternating current, examples of alternating current include current having a waveform in which the polarity changes alternately, such as alternating current superimposed current, rectangular wave current, and pulse wave current. Note that an inorganic or organic acid such as boric acid, oxalic acid, tartaric acid, sulfuric acid, etc. may be added to the above bath.

(Function) When anodized, a porous anodic oxide film 1 as shown in FIG. 1, which is a schematic cross-sectional view, is obtained.

In the figure, 2 is a hole, 4 is a base material made of aluminum or its alloy, 5 is a barrier layer, and 6 is the bottom of the hole 2. Furthermore, when re-anodizing, the diameter L of the pores 2 of the coating 1 (the first
The re-anodized film 1 having holes 2a as shown in FIG. 2 is obtained.

When the anodic oxide film 1 shown in FIG. 1 is electrolytically colored, as shown in FIG.
is precipitated. Due to the light interference effect caused by the metal 3, the surface of the base material 4 emits a predetermined color.

That is, the surface of the base material 4 is colored.

When the AC electrolytic treatment is performed, an elution reaction of the metal 3 deposited in the pores 2 occurs in the anode portion. At that point, hydrogen gas is generated due to the electrolysis reaction of water at the cathode. The metal 3 in the pores 2 is eluted from the pores 2 by this hydrogen gas, as shown in FIG. That is, the eluted area is decolored.

For example, when the base material 4 is placed upright in a bath, the decolorized portions 10 are formed in the form of streaks, as shown in FIG.

Further, when the base material 4 is placed in the bath with the coating 1 facing upward, the decolorized portions 10 are formed in the form of particles, as shown in FIG. This results in a pattern consisting of the bleached portion 10 and the colored portion 20 (
A colored pattern) is obtained. Since this pattern is obtained simply by eluting the metal 3, the performance of the coating 1 does not change at all.

The degree of decolorization in the decolorization section 10 depends on the amount of hydrogen gas generated, and the number of decolorization sections 10 depends on the number of locations where hydrogen gas is generated.

These are controlled by current density, intensity, processing time, etc.

Further, the shape of the decolorizing section 10 depends on how the base material 4 is held in the bath. Therefore, it is easy to control the shape, number, etc. of the pattern with respect to color, and a desired colored pattern can be obtained.

Furthermore, when an inorganic acid or an organic acid is added to an AC electrolytic bath, the conductivity in the bath improves, and the generation of hydrogen gas increases.
This makes patterning easier.

Further, the dissolution ability when the metal 3 in the pores 2 is eluted as ions is increased. Furthermore, an anodic oxidation reaction occurs at the anode,
As shown in FIG. 7, the thickness D of the barrier layer 5 is increased and the durability is improved.

Furthermore, when the re-anodized film 1 having the pores 2a with enlarged diameters shown in FIG. It is obtained as different colors rather than shades of the same color.

That is, when the re-anodized film 1 is subjected to electrolytic coloring treatment, the color of the surface of the film 1 changes depending on the current application time. Then, when AC electrolytic treatment is performed, a decolorized portion 10 is generated, and a decolorized portion 1
The color of 0 changes in the opposite direction to the color change in the case of electrolytic coloring treatment depending on the current application time. Therefore, a pattern is obtained in which the decolorized portion 10 and the colored portion 20 are different colors.

(Effect of the invention) According to the processing method, the colored pattern of aluminum and its alloy of the present invention is formed by forming a porous anodic oxide film on the surface of aluminum or its alloy by anodizing treatment, and having a predetermined metal salt. The anodized film is electrolytically colored in a bath, then AC electrolytically treated in a bath mainly containing an alkali metal salt, an alkaline earth metal salt, or a mixed salt thereof, and anodized with the generated gas. Since the precipitated metal in the film pores is partially eluted, the desired colored pattern can be obtained by controlling the shape, number, etc. of the color pattern on the product without changing the performance of the anodic oxide film at all. I can do it.

Furthermore, by adding an inorganic acid or an organic acid to the bath in which AC electrolytic treatment is performed, patterns can be easily applied, and the barrier layer can be thickened to improve durability.

Furthermore, by using a re-anodized film as the anodized film, a pattern consisting of different colors can be obtained.

(Example) 1st Example A flat aluminum material (A606B-T5 material) was attached to a racking jig, pretreated by a normal method, and then anodized in a 17% by weight sulfuric acid bath. An anodic oxide film with a thickness of 9 μm was obtained.

This was successively treated under the electrolytic coloring conditions and AC electrolytic conditions shown in the table. Note that the aluminum material was vertically immersed in the AC electrolysis bath. As a result, a streak-like colored pattern as shown in FIG. 5 and the color tone shown in the table was obtained.

[Table] Second Example After obtaining an anodic oxide film with a thickness of 9 μm in the same manner as in the first example, it was re-anodized in a 10% by weight phosphoric acid bath at DC20VX for 10 minutes at 20°C. A re-anodized film with enlarged pore size was obtained. This re-anodized film was applied at 5g/
j! It was electrolytically colored in a mixed electrolytic bath of stannous sulfate, 5 g/it sulfuric acid, 10 g/AI ammonium sulfate, and 2 g/I cresol sulfonic acid under conditions of AC 15 V x 5 minutes, and colored green. Then 30g/II! Boric acid, 5g
AC32VX3 in a mixed bath of /ρ sodium tetraborate
AC electrolytic treatment was performed under conditions of 0 seconds to 5 minutes. As a result, a striped pattern as shown in FIG. 5 was obtained in which the color tone of the decolorized portion 10 changed as follows depending on the AC current application time.

30 seconds...bluish-purple, 1 minute...magenta, 2 minutes...red, 3 minutes...complementary color, 4 minutes...yellow, 5 minutes...pale yellow Such decolorization part 10 The reason why the colored parts 20 and 20 have different colors is that during the electrolytic coloring of the re-anodized film, the color tone varies from pale yellow, yellow, complementary color, red, reddish-purple, bluish-violet, and green depending on the coloring time. This is because the color tone changes sequentially, and the color tone change due to decolorization by AC electrolytic treatment is in the opposite direction to the above.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional diagram showing the surface of the base material after anodizing treatment,
Figure 2 is a schematic cross-sectional diagram showing the surface of the base material after re-anodizing treatment, Figure 3 is a schematic cross-sectional diagram showing the surface of the base metal after electrolytic coloring treatment, and Figure 4 is a schematic cross-sectional diagram of the base material surface where metal has been eluted. A schematic cross-sectional view showing the surface. Figure 5 is a diagram showing the oxide film surface when the base material was subjected to AC electrolytic treatment while standing in the bath. Figure 6 is a diagram showing the surface of the oxide film when the base material was placed in the bath. FIG. 7 is a schematic cross-sectional view showing the surface of the base material with a thick barrier layer. 1... Anodized film, 2.2a... Hole, 3... (precipitated) metal, 4...
... Base material, 5... Barrier layer, 10... Decolorization part, 2
0... Colored part Figure 5 Figure 6

Claims (3)

[Claims] (1) Form a porous anodic oxide film on the surface of aluminum or its alloy by anodizing treatment, electrolytically color the anodic oxide film in a bath containing a specified metal salt, and then apply an alkali metal salt or Aluminum characterized by being subjected to AC electrolytic treatment in a bath mainly containing an alkaline earth metal salt or a mixed salt thereof, so that the precipitated metal in the pores of the anodic oxide film is partially eluted by the generated gas. and a method for coloring and patterning its alloy. (2) The method for coloring and patterning aluminum and its alloys according to claim 1, wherein an inorganic acid or an organic acid is added to the bath for performing the AC electrolytic treatment. (3) The anodic oxide film is colored and patterned on the aluminum and its alloy according to claim 1, in which the pore diameter of the previously formed anodic oxide film is enlarged by twice anodizing treatment. Processing method.