JPH04246194A - Method for coloring aluminum anodic oxide film - Google Patents

Abstract

PURPOSE:To easily color an Al anodic oxide film in various color tones by electrolyzing the film in an electrolytic bath contg. Ni salts, Co salts, etc., and converting the deposit in the film surface pore into the sulfide by AC electrolysis. CONSTITUTION:An Al base material 4 is anodized to form an Al anodic oxide film 1 on the surface through a barrier layer 5. The film 1 is again anodized to form a pore 2a of bottle-shaped profile on the surface. The film 1 is electrolyzed in an electrolytic bath contg. one or plural kinds among Ni, Co, Sn, Fe, Cu, Zn, Cd, Ag and Mn salts, and a deposit resulting from the metal salts in the bath is formed in the pore 2a. The film 1 is AC-electrolyzed in an aq. soln. contg. a sulfur-contg. compd. to convert the deposit into the sulfide 3a. The Al anodic oxide film 1 is colored in this way in the various color tones controlled by the sulfides.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coloring an anodic oxide film of aluminum or its alloy, and it relates to a method that can easily control and obtain a variety of color tones based on sulfides. The obtained colored film is
For example, it is suitably used for exterior products such as sashes, building exterior panels, doors, fences, and balconies.

0002

2. Description of the Related Art With the recent diversification of consumer lifestyles and demand preferences, there is a growing demand for products made of aluminum or its alloys to be colored in various colors. This coloring is generally performed by electrolytically treating an anodic oxide film of aluminum or its alloy (hereinafter referred to as an aluminum anodic oxide film) to form colored precipitates in the pores on the surface of the film.

Japanese Patent Publication No. 58-30397 discloses a method of coloring an aluminum anodic oxide film by precipitating sulfides into the pores on the surface of the film. This method is characterized by electrolytically treating an aluminum anodized film in an electrolytic bath containing as main components a substance that decomposes to release sulfur and a stannous salt.

0004

[Problems to be Solved by the Invention] However, in the above method, since tin changes into sulfide at the same time as it is deposited, the sulfide becomes electrically resistive, making it difficult for current to flow, and tin cannot be deposited smoothly. For this reason, only pale yellow to golden colors can be obtained. That is, with the above method, it is not possible to obtain a deep color tone based on sulfide, and furthermore, the color tone cannot be easily controlled because it is difficult to precipitate tin.

[0005] An object of the present invention is to provide a method for coloring an aluminum anodic oxide film that can easily control and obtain various color tones based on sulfides.

[0006]

[Means for Solving the Problems] The method for coloring an aluminum anodic oxide film of the present invention is to color an aluminum anodic oxide film using Ni salt, Co salt, Sn salt, Fe salt, Cu salt, Zn salt, Cd salt, Ag salt, etc. A precipitate based on the metal salt in the electrolytic bath is formed in the pores of the surface of the film by electrolytic treatment in an electrolytic bath containing one or more types of salts, Mn salts, and then a sulfur-containing compound is formed. The method is characterized in that the precipitates are changed into sulfides by alternating current electrolysis in an aqueous solution containing them.

Furthermore, in the present invention, it is preferable to use an aluminum anodic oxide film in which the pores on the surface of the film are shaped like a bottle in longitudinal section by re-anodizing.

[0008] A normal anodic oxidation method is employed to form the aluminum anodic oxide film. That is, for example, inorganic acids such as sulfuric acid, phosphoric acid, chromic acid, or organic acids such as oxalic acid, sulfosalicylic acid, malonic acid, or sodium hydroxide,
It is formed by electrolysis using direct current, alternating current, pulse, PR waves, or AC/DC superposition method in an electrolytic bath of an alkaline aqueous solution such as trisodium phosphate.

[0009] Re-anodizing treatment uses phosphoric acid, pyrophosphoric acid,
This is carried out by electrolyzing in an electrolytic bath of sulfuric acid or a mixed acid thereof in the same manner as the anodic oxidation treatment described above.

[0010] Electrolytic treatment in an electrolytic bath containing one or more salts among Ni salt, Co salt, Sn salt, Fe salt, Cu salt, Zn salt, Cd salt, Ag salt, and Mn salt, This is carried out by using carbon as a counter electrode in a bath and applying an alternating current or direct current voltage. Additionally, additives such as boric acid and sulfuric acid may be added to the bath.

Electrolytic treatment in an aqueous solution containing a sulfur-containing compound is carried out by applying an alternating current voltage or alternating forward and reverse pulses. As the sulfur-containing compound, for example, sulfuric acid, sulfite, ammonium persulfate, ammonium thiosulfate, ammonium sulfide, etc. are used.

After the alternating current electrolytic treatment, a normal sealing treatment is performed.

[0013]

[Operation] The aluminum anodic oxide film obtained by the usual anodic oxidation method is porous as shown in FIG. 1, which is a schematic cross-sectional view. In the figure, 1 is an aluminum anodized film, 2 is a hole, 4 is a base material of aluminum or its alloy, and 5 is a barrier layer.

When the re-anodizing treatment is performed, the diameter L (FIG. 1) of the pores 2 of the coating 1 is enlarged, and the pores 2a having a bottle-shaped longitudinal section as shown in FIG. 2 are obtained.

[0015] Then, the previous electrolytic treatment, that is, Ni salt, Co salt,
Sn salt, Fe salt, Cu salt, Zn salt, Cd salt, Ag salt, M
As shown in FIG. 3, precipitates 3 based on the metal salts contained in the bath are formed in the pores 2a by electrolytic treatment in an electrolytic bath containing one or more salts among n salts. do. This precipitate 3 is obtained in the following states: (1) an elemental metal, (2) a mixture of an elemental metal and a metal oxide or hydrate, or (3) a metal oxide or hydrate. . The amount of precipitation can be controlled relatively easily by adjusting the voltage and time during electrolytic treatment.

Then, by a subsequent electrolytic treatment, that is, an AC electrolytic treatment in an aqueous solution containing a sulfur-containing compound, the precipitate 3 changes into a sulfide 3a, as shown in FIG. In this electrolytic treatment, when the voltage is sufficiently high and the electrolytic time is sufficiently long,
All of the precipitates 3 become sulfides, but when this is not the case, only a part of the precipitates 3 becomes sulfides. That is, the rate of conversion to sulfide can be easily controlled by adjusting the voltage and time during electrolytic treatment.

By the way, the color tone of each metal sulfide is as follows. NiS (black), CoS (black), SnS (brown),
SnS2 (yellow), FeS (black), Fe2S3 (black), C
u2S (black), CuS (black), ZnS (white), CdS (
orange), Ag2S (black), MnS (red or green). Therefore, if all of the precipitates 3 become sulfides in the subsequent electrolytic treatment, the color tone of the film will be as described above, but the precipitates 3
If only a part of the precipitate becomes sulfide, the color tone will be a mixture of the color tone of the precipitate 3 and the color tone of the sulfide. These color tones vary from light to dark depending on the amount of precipitate 3 obtained in the previous electrolytic treatment. For example, C
When using d salt, the precipitate 3 consists of Cd alone and C
A mixture with d oxide (or hydrate) is obtained, and the color tone becomes pale yellow to brown, and when it changes to sulfide, it becomes golden yellow to orange. Also, Ni, Co, whose sulfide is black,
When Fe, Cu, and Ag are used, the color tone becomes gray when part of the precipitate 3 becomes sulfide.

That is, according to the present invention, in addition to the change in color tone from light to dark based on the amount of precipitate 3, the color tone of precipitate 3 and the color tone of sulfide are mixed based on the rate of change to sulfide. The resulting color tones are very diverse, and since the amount of precipitate 3 and the rate of change to sulfide can be easily controlled, it is possible to obtain a variety of colors. A desired color tone can be easily obtained from among various color tones. Since metal sulfides are chemically very stable compounds, coatings colored with metal sulfides will not fade or change color even if exposed outdoors for a long time. Therefore, the colored film obtained by the present invention can be used for, for example, sashes,
Suitable for use in exterior products such as building exterior panels, doors, fences, and balconies.

[0019] In the above, the case where the re-anodized film shown in Fig. 2 is used is explained, but similarly, when the anodized film shown in Fig. 1 is used, the color tones obtained are very diverse. Moreover, the desired color tone can be easily obtained from among a variety of color tones. However, when a re-anodized film is used, the reaction efficiency is good because the contact area between the precipitates 3 in the pores and the electrolyte is large, so the conversion to sulfides progresses smoothly and the obtained The resulting color tone is clearer and darker.

[0020]

As described above, according to the present invention, in addition to the change in color from light to dark, the change in color from a mixture of precipitate and sulfide to sulfide can be realized. It is possible to obtain a wide variety of color tones. Furthermore, since the amount of precipitates and the rate of conversion to sulfides can be easily controlled, a desired color tone can be easily obtained from among a variety of color tones. Since the resulting color tone is based on sulfides, it will not fade or fade even if the film is exposed to the outdoors for long periods of time.
It does not change color and is stable.

Furthermore, by using an aluminum anodic oxide film in which the pores on the surface of the film have become bottle-shaped in longitudinal section by re-anodizing, a clearer and darker color tone can be obtained.

[0022]

[Example] Aluminum extruded shape (JIS designation “A60”)
63S-T5'') was anodized in a sulfuric acid bath to form a 9μ
An anodic oxide film (hereinafter referred to as the first film) having a thickness of m was obtained. Further, the first film was re-anodized by applying a DC voltage of 16 V for 10 minutes in a 10% by weight phosphoric acid bath at 25°C, so that the pores on the film surface became bottle-shaped in vertical section. A film (hereinafter referred to as a second film) was also obtained. For each of the first and second films, a first electrolytic treatment was performed under various conditions shown in Table 1, and a subsequent electrolytic treatment was performed under various conditions shown in Table 2. The table also shows the color tones obtained. Further, A to H in Table 1 indicate the obtained first coatings, and Table 2 indicates that the first coatings A to H in Table 1 were used.

[0023]

[Table 1]

[0024]

[Table 2]

As shown in Table 2, a wide variety of sulfide-based shades were obtained. Also, it is better to use the second film.
The color tone became clearer and darker.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an aluminum anodic oxide film.

FIG. 2 is a schematic cross-sectional view showing an aluminum anodized film that has been re-anodized.

FIG. 3 is a schematic cross-sectional view showing the aluminum anodic oxide film after the previous electrolytic treatment.

FIG. 4 is a schematic cross-sectional view showing an aluminum anodic oxide film after subsequent electrolytic treatment.

[Explanation of symbols]

1 Aluminum anodic oxide film 2, 2a hole 3 Precipitate 3a Sulfide 4 Base material

Claims (2)

[Claims] Claim 1: Aluminum anodic oxide film is coated with Ni salt, C
o salt, Sn salt, Fe salt, Cu salt, Zn salt, Cd salt, Ag
A precipitate based on the metal salt in the electrolytic bath is formed in the pores of the surface of the film by electrolytic treatment in an electrolytic bath containing one or more types of salts, Mn salts, and then a sulfur-containing compound is formed. A method for coloring an aluminum anodic oxide film, which comprises changing the precipitates into sulfides by alternating current electrolysis in an aqueous solution containing the precipitates. 2. The method for coloring an aluminum anodic oxide film according to claim 1, wherein the aluminum anodic oxide film is one in which the pores on the surface of the film are bottle-shaped in longitudinal section by re-anodizing treatment.