JPS5830398B2 - Electrolytic coloring bath composition of aluminum anodic oxide film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrolytic coloring bath compositions for aluminum anodic oxide films.

Here, the term "aluminum anodic oxide film" refers to an oxide film obtained by subjecting the surface of aluminum or aluminum alloy to anodic oxidation treatment using sulfuric acid electrolysis or a conventional method.

Conventionally, the coloring method invented by Japanese Patent Publication No. 38-1715 and Japanese Patent Publication No. 49-48824 is well known as a representative method for electrolytic coloring of aluminum anodic oxide films. The formed aluminum or aluminum alloy is subjected to alternating current electrolysis in the case of the former (Japanese Patent Publication No. 38-1715) in a coloring bath containing metal salts, and electrolysis in the case of the latter (
In the case of Japanese Patent Publication No. 49-48824), coloring is done by direct current cathode electrolysis.

If a selenium salt (for example, selenium dioxide or sodium selenite) is used in the coloring bath, a colored film ranging from lemon gold to deep gold can be obtained in an electrolytic coloring bath containing only these selenium salts.

However, when trying to obtain a gold colored film by using selenium salt in a coloring bath, processing costs are high because selenium salt is more expensive fK than other metal salts, and it is difficult to obtain a deep color. If the electrolysis time is too long, there is a risk of film destruction or spalling, so of course the workability of electrolytic coloring is poor, and the range of color tones that can be obtained is narrow, such as uniform coloring such as reddish gold. I would like to be able to obtain a film.

Therefore, as a result of various research and experiments over many years on this point, the present inventor found that when aluminum or aluminum alloy subjected to anodizing treatment is electrolytically colored in a coloring bath containing selenium salt, the coloring bath When appropriate amounts of specified metal salts, specifically sulfate and zinc sulfate, are added, film breakage and spalling do not occur even if the electrolytic coloring time is extended, making it possible to eliminate conventional coloring methods. A stable colored film with a wide range of colors can be obtained with a much smaller amount of selenium salt,
Not only was it possible to drastically reduce the processing cost, but they discovered that by extending the coloring time, they could obtain a colored film with a strong reddish gold color, which was impossible to achieve with a coloring bath containing selenium salt alone. This electrolytic coloring bath composition solves all of the above problems at once.

Below, the composition of the electrolytic coloring bath according to the present invention will be explained in more detail. First, the concentration of selenium salt in the coloring bath is not particularly limited, but it is not necessary to contain a large amount as in the conventional case, and the concentration of selenium salt in the coloring bath is not particularly limited. In this case, an amount of about 59/l to 109/l is dissolved and used.

Next, of the copper sulfate and zinc sulfate added to the selenium salt coloring bath, the appropriate concentration of copper sulfate is 0.1 to 59/l, and the coloring properties can be changed by adjusting the concentration. If the concentration of copper sulfate is increased, it becomes easier to obtain a gold-colored film with a strong reddish tint, and no additives (addition of only zinc sulfate) have no effect at all.

In addition, the appropriate concentration of zinc sulfate is 0.1 to 1 g/l.
When controlling a colored bath, an appropriate amount is 0.1 to 0.5 g/l, but even if the concentration is changed, no change in the color tone of the colored film is observed, and no additives are effective. If it is more than 1, it is uneconomical, and zinc sulfate plays an auxiliary role in the precipitation of selenium into the pores of the film.

The electrolytic coloring bath of the present invention has the composition as described above,
If this is used for electrolytic coloring of an aluminum anodic oxide film, as is clear from the Examples and Comparative Examples described later,
By simply adding an appropriate amount of copper sulfate and zinc sulfate to a selenium salt coloring bath, it is possible to extend the coloring time of direct current coloring, and as a result, the coloring range is wider than that of a selenium salt bath alone. A film is obtained, and the longer the coloring time is, the better the stickiness becomes, so the film is less likely to break and the workability is very good.A stable gold colored film can be obtained with a much smaller amount of selenium salt than the conventional method. can be obtained.

In addition, in the case of AC coloring, the coloring time is originally long, so the effect of lengthening the coloring time for one coloring is extremely difficult to recognize. A colored film is obtained.

Copper sulfate and zinc sulfate added to the selenium salt coloring bath play an auxiliary role in the coloring of selenium in both direct current and alternating current coloring. It is thought that direct steel precipitation contributes to the color development.

Next, a specific example of electrolytic coloring of an aluminum anodic oxide film using the bath composition of the present invention, a comparative example of electrolytic coloring using a conventional selenium salt alone bath, and the results of a weather resistance test of the sample obtained thereby. .

Example 1 Sample A6063S aluminum material was etched in a sodium hydroxide solution with a concentration of 10 parts at a bath temperature of 50°C for 5 minutes, then neutralized in a nitric acid solution with a concentration of 10 parts, washed with water, and then: A current density of 1.
5 A/dm', electrolysis time 30 minutes, and bath temperature 20 ± 1 ° C. After anodizing treatment, the sample was used as a cathode in a coloring bath with the following composition, and carbon was used as a counter electrode at 14 V.
DC current was applied.

Selenium dioxide 10j; l/72 Copper sulfate 1g/l Zinc sulfate 0.1971 Bath temperature 20°C As a result, uniform coloration of lemon gold at 60 seconds, dark gold at 180 seconds, and reddish gold at 300 seconds. A film was obtained.

Example 2 Sample A6063S aluminum material was anodized in the same manner as in Example 1, the resulting sample was used as a cathode, and a 12V DC current was applied in a coloring bath having the following composition using carbon as a counter electrode.

Selenium dioxide 59/l Copper sulfate 1.5 fl/12 Zinc sulfate 0.1971 Bath temperature 20°C As a result, a uniform colored film of lemon gold after 60 seconds of current application, gold at 120 seconds, and reddish gold at 240 seconds. was gotten.

Example 3 Sample A6063S aluminum material was anodized in the same manner as in Example 1, and the obtained sample was energized at 14 V AC using a carbon counter electrode using a coloring bath having the following composition.

Sodium selenite 5g/l Copper sulfate 1g/11 Zinc sulfate 0.19/il Bath temperature 20℃ As a result, lemon gold, 360
Gold in seconds, reddish gold in 480 seconds, 600
A uniformly colored film of reddish gold was obtained in seconds.

Comparative Example 1 Sample A6063S aluminum material was anodized in the same manner as in Example 1, the obtained sample was used as a cathode, and selenium dioxide: 509/II, bath temperature: 20°C, colored with selenium salt alone. When a 14 V direct current was applied in the bath using a carbon plate as a counter electrode, a gold colored film was obtained after 180 seconds of current application, but the film was destroyed after 240 seconds.

Comparative Example 2 Sample A6063S aluminum material was anodized in the same manner as in Example 1, the resulting sample was used as a cathode, and selenium salt was colored alone at 10β/l of selenium dioxide and 20°C of bath temperature. When a 12 V direct current was applied in the bath using a carbon plate as a counter electrode, a pale gold colored film was obtained after 30 seconds of current application, but the film was destroyed after 60 seconds.

Comparative Example 3 Sample A6063S atvinium material was anodized in the same manner as in Example 1, and the obtained sample was heated in a coloring bath with sodium selenite...59//l and bath temperature...20°C. When a commercially available AC 14 V current was applied using a carbon plate as a counter electrode, a gold colored film was obtained after 480 seconds of current application, but a spot X-ring occurred after 600 seconds.

In Comparative Example 1 and Comparative Example 2, the coloring time is shorter than in Example 1 and Example 2, respectively, and the film breaks down more quickly, so the workability is poor and the range of color tones obtained is poor. Further, in Comparative Example 3, spalling was observed, indicating that the change in color tone was small.

The samples obtained in the weather resistance test examples and comparative examples were sealed with pure water at 10°C for 20 minutes, and then tested using a weather resistance tester (Sunshine Decor Cycle Weather Meter, manufactured by Suga Test Instruments Co., Ltd.).
! A weather resistance test was conducted for 250 hours using LC and RF, and the results are shown in the table below.

From the table above, it can be seen that the sample of Example 1.2.3 has no change, whereas the sample of Comparative Example 1.2 has changed color or bleached, indicating that its weather resistance is inferior to that of Example 1. It shows.

Claims (1)

[Claims] 1 0.1-3 g of copper sulfate in an electrolytic coloring bath containing selenium salts
/it and zinc sulfate from 0.1 to Ijj/72.