JPS5833318B2 - Aluminum mataha Aluminum material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coloring aluminum or an aluminum alloy (hereinafter simply referred to as aluminum).

As is well known, unlike other metal materials such as iron and copper, aluminum has the feature that it can be colored into beautiful colors by surface treatment, so colored aluminum is often used for decorative and kitchen purposes. It is widely used for construction materials such as aluminum sash and aluminum fittings, as well as for equipment.

The methods of coloring aluminum can be roughly divided into (a)
It can be classified into three types: chemical methods, (b) electrochemical methods, and (c) physical methods. Among these methods, coloring methods utilize the porosity of the anodic oxide film formed on the aluminum surface. Since the electrochemical method (b) is the most superior in terms of coloring stability and other various aspects, most factories now use this method for coloring.

Conventional electrochemical methods include (A) a method of anodizing aluminum and then immersing it in a water-soluble or oil-soluble dye solution to color it;

(B) An inorganic coloring method in which aluminum is anodized and then immersed in an aqueous solution of a metal salt to undergo alternating current electrolysis treatment.

(C) A method of developing color by anodizing with a special alloy or electrolyte.

(D) A method of anodizing aluminum and then immersing it in an inorganic pigment solution to color it.

etc. are known.

However, among the methods listed in (A) to (D) above, method (A) is not suitable for exterior use because the dye has very low sunlight fastness; liquid adjustment,
It is troublesome to control the electrolytic conditions, and it is difficult to obtain a uniformly colored film.(Method (J7) requires a specially prepared aluminum alloy to make the color development uniform, so the raw material Not only is the cost high, but the types of colors are limited; method (D) generally tends to cause uneven coloring, and the types of colors are limited; Since there are drawbacks such as difficulty in management and complexity of the coloring process, there has been a strong desire to develop a new aluminum coloring method that can solve all of these problems.

This invention has succeeded in solving the above-mentioned problems at once by applying completely new creativity to the composition of the electrolytic solution and colored immersion liquid used in anodizing film treatment, and using a unique method. Specifically, after aluminum or aluminum alloy is anodized with an electrolytic solution consisting of a mixed acid of sulfuric acid and phosphoric acid, it is anodized with ferric ammonium oxalate, silver nitrate, cobalt acetate, chromium potassium sulfate, and cupric ammonium chloride. It is characterized by being colored by immersing it in one type of aqueous solution.

If aluminum is colored by such a method, all of the drawbacks of the methods (A) to (D) above can be overcome, and a colored film with an even and uniform color tone can be obtained with easy liquid management. Of course, it is possible to obtain colors that are difficult to color with conventional inorganic pigments, and the cost of raw materials and processing equipment is low.In particular, products colored by this method have excellent sunlight fastness. This makes it ideal for use as an exterior building material, and after coloring, the surface of the film can be electrophoretically painted or immersed in the same way as before.

In addition, when coloring by the dipping method after the anodic oxide film is formed, it is said that the size, depth, and number of pores in the anodic oxide film have a large effect on the coloring property. The present invention also shows that the anodic oxide film obtained using an electrolytic solution consisting of a mixed acid with a sulfuric acid has very good colorability and can easily obtain a deep color compared to the conventional anodic oxide film obtained in a sulfuric acid solution. This is one of the excellent features of the method.

Specific examples of the present invention will be listed below.

Example 1 An aluminum plate was pretreated by a conventional method, anodized under the following conditions, and then treated with an aqueous ferric ammonium oxalate solution (
A uniform reddish-brown film was obtained when the sample was immersed for 15 minutes at a temperature of 10 ft/l (60° C.).

This colored film was measured at 20% by Sunshine Weatherometer.
No discoloration occurred even after irradiation for 0 hours.

Example 2 An aluminum plate was pretreated by a conventional method, anodized under the same conditions as in Example 1, and then treated with a silver nitrate aqueous solution (10t/
1, 60° C.) for 15 minutes, a uniform brown film was obtained.

Example 3 An aluminum plate was pretreated by a conventional method, anodized under the same conditions as in Example 1, and then treated with an aqueous cobalt acetate solution (1
0 g/l, 60° C.) for 15 minutes, a uniform slightly reddish film was obtained.

Example 4 An aluminum plate was pretreated by a conventional method, anodized under the same conditions as in Example 1, and then immersed in a chromium potassium sulfate aqueous solution (IOS'//!, 60°C) for 15 minutes. A green film was obtained.

Example 5 An aluminum plate was pretreated by a conventional method, anodized under the same conditions as in Example 1, and then immersed in a cupric ammonium chloride aqueous solution (10 L?/1160°C) for 15 minutes, resulting in a uniform blue color. A film was obtained.

Claims (1)

[Claims] 1 After anodizing aluminum or aluminum alloy with an electrolytic solution consisting of a mixed acid of sulfuric acid and phosphoric acid, it is anodized with one of ferric ammonium oxalate, silver nitrate, cobalt acetate, chromium potassium sulfate, and cupric ammonium chloride. A method for coloring aluminum or aluminum alloys, which method comprises immersing aluminum or aluminum alloys in various aqueous solutions.