JPS643958B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for coloring aluminum or an aluminum alloy (hereinafter simply referred to as aluminum). [Prior Art] Conventionally, methods for coloring aluminum that has been subjected to anodic oxide film treatment using an inorganic compound dipping bath include (a) one-component dipping method. (b) Two-liquid alternate dipping method. (c) A method using sulfur compounds in sulfuric acid AC electrolysis. etc. are widely known. Among these, the one-liquid immersion method (a) is a method in which an inorganic compound is dissolved in water and the anodic oxide film on the aluminum surface is immersed in it to color it.Currently, ferric oxalate is used as an inorganic compound in the bath. Salt is mainly used. The coloring in this case is achieved by hydrolyzing the ferric oxalate salt to form ferric hydroxide, which is then precipitated in the form of triiron tetroxide. In addition, in the two-liquid alternate dipping method (b), two inorganic compound baths are prepared, and the anodic oxide film on the ammonium surface is alternately dipped in the two baths, and the chemical reaction causes colored substances to be added to the film. It is a method of depositing
For example, it is possible to produce a color close to black by alternately immersing it in solutions of lead acetate and aluminum sulfide, or to produce a yellow color by alternately immersing it in solutions of silver nitrate and ammonium sulfide. Furthermore, in the method (c) of using sulfur compounds in sulfuric acid AC electrolysis, when aluminum is subjected to AC electrolysis in a sulfuric acid bath, sulfur compounds are contained in the film. This is a method of coloring by producing metal salts. In this case, coloring can accelerate the reaction by sealing treatment. However, AC coatings are generally considered to have inferior coating performance compared to DC coatings. [Problem to be solved by the invention] By the way, among the three coloring methods mentioned above, (a)
The one-component immersion method has a simpler treatment process and requires less immersion time than other methods (b) and (c), and the colored film has extremely good durability in terms of light resistance and outdoor exposure. Due to the mechanism of coloring, there are very few types of inorganic compounds that can be used in practical immersion baths. It was difficult to obtain deep, vivid coloring with such rich colors. The purpose of the present invention is to stably color aluminium, which has been subjected to anodic oxidation treatment, using an inorganic compound immersion bath in a simple process with a variety of dark colors using a unique bath composition. The object of the present invention is to provide a novel method for coloring aluminum that can be obtained in a certain form. [Means for Solving the Problems] As a result of various studies and experiments regarding this point, the present inventor has found that one of ammonium metavanadate, sodium chromate, potassium chromate, and ammonium chromate is added to the immersion coloring bath. It was discovered that by using a bath containing a mixture of one type of metal salt and other water-soluble metal salts, it was possible to obtain deep and vivid coloring with a variety of colors.Based on this knowledge, the present invention was developed. They succeeded in developing a coloring method. That is, the above purpose is to treat aluminum or aluminum alloy that has been subjected to anodic oxidation film treatment to ammonium metavanadate, sodium chromate,
Coloring is achieved by immersion in a mixed bath of either potassium chromate or ammonium chromate and a water-soluble metal salt that does not contain vanadium or chromium. Preferred metals constituting the water-soluble metal salt include nickel, cobalt, tin, and iron. The anodic oxidation coating applied to the surface of aluminum prior to the immersion coloring of the present invention can be sufficiently carried out with a normal sulfuric acid direct current coating, but is not necessarily limited to this. For example, mineral acids or organic acids other than sulfuric acid may be used, and coloring can also be achieved by alternating current electrolysis or alternating current electrolysis. In the next immersion coloring step, a mixed bath of one of ammonium metavanadate, sodium chromate, potassium chromate, and ammonium chromate and a water-soluble metal salt that does not contain vanadium or chromium may be used. This is an essential requirement. [Operation and Effect] When an anodic oxide film of aluminum is immersed in a mixed bath of metavanadate, chromic acid, etc. and a water-soluble metal salt other than vanadium or chromium, vanadium or chromium is adsorbed to the anodic oxide film, At the same time, it is thought that the metal combines with the vanadium or chromium to form an insoluble salt, which stably colors the oxide film. Therefore, by appropriately setting the combinations of ammonium metavanadate, sodium chromate, potassium chromate, ammonium chromate, and water-soluble metal salts, it is possible to stably achieve deep and vivid coloring with various colors. can get. In addition, in this coloring process, it is sufficient to simply immerse the anodized aluminum in a bath, so that the process can be carried out in a simple process. Furthermore, since vanadium or chromium is supplied to the bath in the form of ammonium metavanadate, ammonium chromate, etc., it is a simple process that allows stable deep and vivid coloring in a short immersion time. You can go to [Examples] Hereinafter, specific embodiments of the coloring method according to the present invention will be explained using typical examples and comparative examples of the present invention. However, the present invention does not necessarily limit to these examples. It is not binding. Example 1 and Comparative Examples 1 and 2 Aluminum alloy plates (6063S) were pretreated in a conventional manner and subjected to direct current electrolysis in a 150 g/sulfuric acid bath at a bath temperature of 20°C and a current density of 1.2 A/dm ² for 30 minutes. , 11μm
After applying the anodized film of Example 1 and Comparative Examples 1 and 2, the following bath compositions were prepared: Example 1 Ammonium metavanadate nickel sulfate 25g/50g/ Comparative example 1 Ammonium metavanadate 25g/ Comparative example 2 Nickel sulfate 50g/ When immersed in the bath for 5 minutes at each temperature shown in Table 1 below, the results shown in Table 1 were obtained.

[Table] Example 2 and Comparative Examples 3 and 4 An aluminum alloy plate (6063S) was pretreated by a conventional method, and then subjected to the same anodic oxidation treatment as in Example 1. Next, Example 2 and Comparative Example 3 below,
Bath Composition of Comparative Example 4 Example 2 Ammonium Chromate Nickel Chloride 20g/15g/Comparative Example 3 Ammonium Chromate 20g/Comparative Example 4 Nickel Chloride 15g/Immersed for 5 minutes at each temperature shown in Table 2 below. However, the results shown in Table 2 were obtained.

[Table] As is clear from the above-mentioned Example 1 and Comparative Examples 1 and 2, and Example 2 and Comparative Examples 3 and 4, in the coloring method of the present invention, ammonium metavanadate + metal salt, ammonium chromate + metal The oxide film develops a deep color depending on the combination of salts. Example 3 An aluminum alloy plate (6063S) was pretreated in a conventional manner and then subjected to the same anodic oxidation treatment as in Example 1. Next, when it was immersed in a bath containing 40 g of ammonium metavanadate/20 g of stannous sulfate at a temperature of 80° C. for 5 minutes, a brown colored film was obtained. Example 4 An aluminum alloy plate (6063S) was pretreated in a conventional manner and then subjected to the same anodic oxidation treatment as in Example 1. Next, when it was immersed in a bath containing 40 g of ammonium metavanadate/20 g of stannic sulfate at a temperature of 80° C. for 5 minutes, a dark yellow-green colored film was obtained. Example 5 An aluminum alloy plate (6063S) was pretreated by a conventional method and subjected to direct current electrolysis in a 150 g/sulfuric acid bath at a bath temperature of 20°C and a current density of 1 A/dm ² for 20 minutes to form an anodic oxide film of 6 μm. After that, it was immersed in a bath containing 50 g of potassium chromate/50 g of nickel sulfate at a temperature of 40° C. for 2 minutes, and a lemon gold colored film was obtained. Example 6 An aluminum alloy plate (6063S) was pretreated by a conventional method and subjected to the same anodic oxidation treatment as in Example 5, and then placed in a bath containing 50 g of sodium chromate/50 g of nickel sulfate at a temperature of 40°C for 2 hours. After immersion for a minute, a lemon gold colored film was obtained. Example 7 An aluminum plate (99.2%) was pretreated by a conventional method and subjected to direct current electrolysis in a 150 g/sulfuric acid bath at a bath temperature of 20°C and a current density of 1.2 A/dm ² for 30 minutes to form an anodic oxide film of 11 μm. After that, it was immersed in a bath containing 25 g of ammonium metavanadate/15 g of cobalt sulfate at a temperature of 100° C. for 5 minutes, and a brownish gold colored film was obtained. Example 8 An aluminum alloy plate (6063S) was pretreated by a conventional method, and heated in a 150 g/sulfuric acid bath at a bath temperature of 20°C.
Direct current electrolysis for 30 minutes at a current density of 1.2A/ ^dm2 , 11μm
After applying the anodized film, it was immersed in a bath containing 20 g of ammonium chromate/15 g of cobalt sulfate at a temperature of 40°C for 5 minutes, and a brownish gold colored film was obtained. Example 9 An aluminum plate (99.2%) was pretreated by a conventional method and subjected to the same anodic oxidation treatment as in Example 8.
Next, when it was immersed in a bath containing 20 g of ammonium chromate/20 g of stannic chloride at a temperature of 80° C. for 2 minutes, a milky green colored film was obtained. Example 10 An aluminum plate (99.2%) was pretreated by a conventional method and subjected to the same anodic oxidation treatment as in Example 8.
Next, when it was immersed in a bath containing 20 g of ammonium chromate/20 g of ferric chloride at a temperature of 80° C. for 5 minutes, a yellow-orange colored film was obtained. Example 11 An aluminum alloy plate (6063S) was pretreated by a conventional method and subjected to the same anodic oxidation treatment as in Example 1, and then placed in a bath containing 20 g of ammonium chromate/15 g of nickel acetate at a temperature of 40°C for 50 minutes. After immersion for a minute, a dark yellow colored film was obtained. Example 12 An aluminum alloy plate (6063S) was pretreated by a conventional method and anodized in the same manner as in Example 1, and then placed in a bath containing 20 g of ammonium chromate/15 g of nickel nitrate at a temperature of 40°C for 50 minutes. After immersion for a minute, a dark yellow colored film was obtained. As mentioned above, if the method of the present invention is applied to coloring aluminum, aluminum that has been subjected to anodic oxidation coating can be colored in a dipping bath of an inorganic compound using a simple process and a short dipping time. It has the advantage of being able to stably provide deep, vivid coloring with a variety of colors.

Claims (1)

[Scope of Claims] 1 Aluminum or aluminum alloy subjected to anodic oxidation film treatment is mixed with any one of ammonium metavanadate, sodium chromate, potassium chromate, and ammonium chromate in an aqueous solution containing no vanadium or chromium. 1. A method for coloring aluminum or an aluminum alloy, which method comprises coloring aluminum or aluminum alloy by immersing it in a mixed bath with a metal salt. 2. The method for coloring aluminum or aluminum alloy according to claim 1, wherein the metal constituting the water-soluble metal salt is any one of nickel, cobalt, tin, or iron.