JPH06184792A - Method for coloring aluminum or aluminum alloy by electroless plating - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an electroless coloring method for aluminum or aluminum alloy without color unevenness and color variation. [Structure] Aluminum or aluminum alloy is anodized to form a porous film, which is treated with a silane coupling agent, immersed in a palladium complex salt solution, and then electroless plated to deposit a metal on the film. Electroless coloring method for aluminum or aluminum alloy. [Effect] After the porous anodic oxide film is formed, there is a step of pretreatment with a silane coupling agent, so that the palladium complex salt solution treatment, which is the subsequent treatment, and the metal deposition by electroless plating are uniformly and reliably ensured. The finally obtained metal film is uniform and free from color unevenness and color variation among processed products, and also has excellent adhesion, weather resistance, corrosion resistance and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless coloring method for aluminum or aluminum alloy.

[0002]

2. Description of the Related Art Various conventional methods for coloring an anodized film of aluminum or aluminum alloy are known, and typical examples thereof are as follows. It is a method of coloring by depositing a metal on an aluminum anodic oxide film by an alternating current electrolysis method (referred to as a conventional example). Since it is excellent in weather resistance, heat resistance and wear resistance, it can be applied to aluminum sashes for building materials etc. It has been put to practical use. This is a method of coloring a metal by depositing it on an aluminum anodic oxide film by an electroless method, and more specifically, it is as follows.

(1) Japanese Patent Publication No. 52-4496 (conventional example) in which a catalyst agent for depositing metal in electroless plating is applied by a conventional treatment method such as sensitizing activation on resin plating. (1)), (2) Japanese Patent Publication No. 2-45704 (referred to as Conventional Example- (2)) aiming at stability of coloring by electrochemically depositing catalyst nuclei.

[0004]

In the above-mentioned conventional example, there is a problem in that the metal is electrically deposited, so that color variations in coloring are likely to occur.

In the above-mentioned conventional example- (1), it is difficult to stably deposit palladium in the sensitizing treatment, so that there is a problem that color unevenness is likely to occur.

The conventional example- (2) has a problem that color unevenness and the like are likely to occur as in the conventional example- (1).

[0007]

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electroless coloring method for aluminum or aluminum alloy which prevents the occurrence of color unevenness and color unevenness. What is provided is to anodize aluminum or an aluminum alloy to form a porous anodic oxide film, treat the anodic oxide film with a silane coupling agent, and then immerse it in a palladium complex salt solution, and then perform electroless plating. The gist is the electroless coloring method of aluminum or aluminum alloy, in which a metal is deposited on the anodized film to color it.

The porous anodic oxide film is formed on aluminum or an aluminum alloy by a conventionally known method, for example, a mineral acid aqueous solution such as sulfuric acid or chromic acid, an organic carboxylic acid such as oxalic acid, or an organic sulfone such as sulfosalicylic acid. Anodizing treatment may be performed with a mixed acid such as acid and sulfuric acid.

Next, the aluminum or aluminum alloy having the porous anodic oxide film formed thereon is immersed in an aqueous solution containing a silane coupling agent or an aqueous solution containing alcohol or the like to chemically modify the surface with the silane coupling agent. To do. Such silane-based coupling agents include aminomethyltrimethoxysilane, aminomethyltriethoxysilane, aminomethyltributoxysilane, aminoethyltrimethoxysilane, aminoethyltriethoxysilane, aminoethyltripropoxysilane, aminoethyltriethoxysilane. Aminosilanes such as butoxysilane, aminopropyltrimethoxysilane and aminopropyltriethoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropylmethyldiethoxysilane, β- (3,4 epoxycyclohexyl)
Epoxysilane such as ethyltrimethoxysilane, γ-
Examples thereof include mercaptosilane compounds such as mercaptopropyltriethoxysilane and γ-mercaptotriethoxysilane.

These silane coupling agents are used as an aqueous solution or an aqueous solution containing an alcohol such as methanol, ethanol, isopropyl alcohol or butanol as described above, and the concentration thereof is 0.01-
10% by weight is optimum, and the treatment temperature is room temperature to
It may be about 70 ° C., and aluminum or aluminum alloy having an anodic oxide film formed thereon may be dipped in these solutions.

Next, the aluminum or aluminum alloy treated with the silane coupling agent is immersed in an aqueous solution of a palladium complex salt to adsorb the palladium complex salt. As the palladium salt, palladium chloride, palladium nitrate, and sulfuric acid are used. Palladium, palladium cyanide or the like is used. The concentration of these is 0.01 to
It may be about 10% by weight.

Next, a metal is deposited on the aluminum or aluminum alloy treated with the palladium complex salt solution by an electroless method. The metals to be deposited are Cu and Cu-
Ni-P, Ni-Co-P, Au-Ni-W-P, Ni
-P, Ni-B, Co-P, Co-B, Fe, Sn, A
Although u, Pd, W and the like are used, one kind or two or more kinds of these metals may be deposited. In order to precipitate these metals, sodium hypophosphite, sodium borohydride, hydrazine, reducing agents such as formalin, lactic acid,
A coloring solution containing a complexing agent such as succinic acid, glycine, tartaric acid, alanine and citric acid, and a stabilizer such as thiourea and an organic acid lead salt is used.

[0013]

[Function] Since there is a step of pretreatment with a silane coupling agent after forming the porous anodic oxide film, the pores of aluminum or aluminum alloy and, in addition, the anodic oxide film of aluminum or aluminum alloy and silane The silanol group of the coupling agent is covalently bonded, and the silane coupling agent is evenly attached, whereby the palladium complex salt obtained by the subsequent treatment (sensitization treatment) and the functional group (amino group) of the silane coupling agent are obtained. Group, epoxy group, thiol group) to promote and promote uniform attachment of the palladium complex salt. As a result, the metal deposition, which is the final step, can be made uniform.

[0014]

【Example】

Example 1. A JIS 1080 plate is used as the aluminum material, and the sulfuric acid concentration is 15%, the temperature is 20 ° C., and the current density is 1.
A porous oxide film having a thickness of 10 μm was formed by treatment at 5 A / dm ^{2 for} 30 minutes. After the treatment, the plate was washed with water and immersed in a solution prepared by adding 0.25% by weight of γ-aminopurpyruethoxysilane to a solvent having a mixing ratio of water and ethanol of 9: 1 at room temperature for 10 minutes. Next, it was immersed in an aqueous solution of palladium chloride-hydrochloric acid (0.02 wt% palladium chloride, 35% hydrochloric acid 2 ml / l) at room temperature for 10 minutes to adsorb palladium chloride. Then, sodium hypophosphite 10g / l, sodium hydroxyacetate 50g / l, lead acetate 0.001g / l, pH
A black film was obtained by precipitating Ni-P by immersing it in a coloring liquid of 4.5 and 50 ° C.

Example 2. The aluminum plate used in Example 1 was treated in the same manner as in Example 1 to form an anodized film. After the treatment, the product was washed with water, and a mixture of water and isopropyl alcohol was mixed with 8: 1 aminoethyltriethoxysilane.
It was immersed in a liquid added with 2% by weight at 30 ° C. for 5 minutes. Next, a palladium chloride / hydrochloric acid aqueous solution (palladium chloride 0.0
2% by weight, hydrochloric acid 35%, 2 ml / l) was immersed at room temperature for 10 minutes to adsorb palladium chloride. Then copper sulphate 7
g / l, potassium sodium tartrate 75 g / l, triethanolamine 10 ml / l, formalin (37%) 25 m
A brown film was obtained by precipitating copper by immersing it in a coloring liquid of l / l, sodium hydroxide 10 g / l, sodium cyanide 0.125 g / l, pH 8.0, and 40 ° C.

[0016]

EFFECTS OF THE INVENTION The colored films obtained in Examples 1 and 2 are uniform and free from color unevenness and color variation among processed products.
Moreover, it was also excellent in adhesion, weather resistance, corrosion resistance and the like.

Claims (1)

[Claims] 1. A method of anodizing aluminum or an aluminum alloy to form a porous anodized film, treating the anodized film with a silane coupling agent, immersing it in a palladium complex salt solution, and then performing electroless plating. An electroless coloring method for aluminum or aluminum alloy, wherein a metal is deposited on the anodic oxide film to color the anodic oxide film.