JPH0450400B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for coloring anodized coatings of aluminum or its alloys used for building products such as sashes, sliding doors, entrances, etc., housing cases, daily necessities, castings, vehicle parts, etc. and
The color tone can be easily controlled and the throwing power can also be improved. (Prior Art and its Problems) 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 coloring an anodic oxide film of aluminum or its alloy (referred to as an aluminum anodic oxide film). As this coloring method, for example, JP-A-53-
22834, 54-85137, the so-called tertiary electrolysis method is well known. This method is a method in which the aluminum anodic oxide film is re-anodized and then electrolytically treated in an electrolytic solution in an aqueous solution of a metal salt to be colored.As shown in FIG. This method is characterized by making the layer height H of the deposited metal 13 uniform and by utilizing the interference effect of light to obtain primary colors such as red, yellow, green, and blue. In order to obtain the desired color tone by this method, metal 13
It is important to control the precipitation and make the layer height H uniform. However, as a coloring bath, Ni, Co,
Since only a metal salt such as Sn is used, the resistance of the metal 13 deposited at the bottom of the pores 12 of the coating 11 is small, so the precipitation of the metal 13 occurs quickly, making it difficult to control the layer height H. be. Therefore, the amount of metal 13 deposited differs depending on the location, resulting in variations in the layer height H, resulting in poor throwing power and poor color tone reproducibility. It is particularly difficult to obtain good blue-based color tones, which are in high demand. By the way, as a method for obtaining good blue-based color tones, the method described in Japanese Patent Application Laid-Open No. 51-99640 is known. This method uses an electrolytic bath of phosphoric acid, chromic acid, or a mixed acid containing sulfuric acid, and
A DC voltage of 150 V is applied to form an anodic oxide film 21 having a branched porous layer as shown in FIG. 8, and metal 23 is deposited on the bottoms of the multi-branched layers 22. However, in this method, the applied DC voltage is high, which increases the industrial equipment cost. The applicant has already obtained Ni, Sn, Ca, Ba,
An application has been filed for a method for obtaining pastel colors by electrolytically coloring in a bath containing Al added to metal salts such as Ti, Zn, Mg, Cu, and Se (Patent Application No. 62
-42300 (Unexamined Japanese Patent Publication No. 63-210295). (Object of the invention) The present invention allows easy control of color tone,
Another object of the present invention is to provide a method for coloring an aluminum anodic oxide film that can also provide good throwing power. (Means for achieving the object) The method for coloring an aluminum anodic oxide film of the present invention includes re-anodizing the aluminum anodic oxide film in an electrolytic bath of phosphoric acid, pyrophosphoric acid, sulfuric acid, or a mixed acid thereof. , Al salt, Ti salt, Mg salt, Ba
salt, one or more kinds of salts among Ca salts, and Ni salt,
It is characterized by carrying out alternating current electrolytic treatment in an electrolytic coloring bath containing only one or more salts among Co salt, Zn salt, Fe salt, Sn salt, Cu salt, and Ag salt. A normal anodic oxidation method is used to form the aluminum anodic oxide film. That is, the aluminum anodic oxide film can be formed by electrolysis of inorganic acids such as sulfuric acid, phosphoric acid, and chromic acid, or organic acids such as oxalic acid, sulfosalicylic acid, and malonic acid, or alkaline aqueous solutions such as sodium hydroxide and trisodium phosphate. It is formed in a bath by electrolysis using direct current, alternating current, pulses, PR waves, or AC/DC superposition. This results in
A porous anodic oxide film 1 as shown in FIG. 1, which is a schematic cross-sectional view, is obtained. In the figure, 2 is a hole;
4 is a base material made of aluminum or its alloy, 5 is a barrier layer, and 6 is the bottom of the hole 2. The re-anodizing treatment is performed by electrolyzing in the same manner as the above-mentioned anodizing treatment in an electrolytic bath of phosphoric acid, pyrophosphoric acid, sulfuric acid, or a mixed acid thereof. As a result, the diameter L of the pores 2 in the film 1 (Fig. 1)
is enlarged, and a hole 2a as shown in FIG. 2 is obtained. Electrolytic coloring baths include Al salt, Ti salt, Mg salt, Ba salt,
One of Ca salts (hereinafter referred to as first group metal salts)
Salt or salts, Ni salt, Co salt, Zn salt, Fe
It contains only one or more kinds of salts among salts, Sn salts, Cu salts, and Ag salts (hereinafter referred to as second group metal salts). The types and concentrations of the metal salts in the first group and the second group are appropriately selected depending on the desired color tone. Generally the first
As the concentration of the metal salts in the group increases, the whiteness increases, and as the concentration of the metal salts in the second group increases, the color specific to the metal becomes darker. Electrolytic coloring is carried out in a bath by using, for example, carbon as a counter electrode and applying an alternating current voltage of about 15 to 25 V. (Function) When AC voltage is applied in the electrolytic coloring bath, the third
As shown in the figure, a white metal oxide (or metal hydrate) 7 based on the metal salt of the first group is precipitated in the pores 2 of the anodic oxide film 1, and at the same time
Metal 3 based on group metal salts is deposited. The metal 3 is obtained by being dispersed in the metal oxide (or metal hydrate) 7. Therefore, metal 3 does not precipitate rapidly, and the amount of metal 3 deposited is controlled on a minute-by-minute basis. Further, the metal 3 is uniformly deposited regardless of where the current flows easily or where it is difficult to flow in the film 1. That is, the tangle properties become good and a uniform color tone can be obtained. Further, due to the light scattering effect caused by the dispersed metal 3, particularly blue-based color tones can be obtained satisfactorily. (Effects of the Invention) The method for coloring an aluminum anodic oxide film of the present invention includes re-anodizing the aluminum anodic oxide film in an electrolytic bath of phosphoric acid, pyrophosphoric acid, sulfuric acid, or a mixed acid thereof, and then applying an Al salt, Ti salt, Mg salt, Ba
salt, one or more kinds of salts among Ca salts, and Ni salt,
The alternating current electrolytic treatment is performed in an electrolytic coloring bath containing only one or more of Co salt, Zn salt, Fe salt, Sn salt, Cu salt, and Ag salt, making it easy to control the color tone. Furthermore, it is possible to obtain a uniform color tone with good tangle properties. (Example) As shown in FIG. 4 and FIG.
The material) 30 was suspended on the electrolytic rod 34 of the electrolytic frame 32, and was anodized in a sulfuric acid bath to obtain an anodic oxide film of a predetermined thickness. [First Example] An anodic oxide film with a thickness of 9μ was obtained by the above method,
This was re-anodized in a 10% phosphoric acid bath at 20°C by applying a 16V DC voltage for 10 minutes. Next, as shown in Table 1, electrolytic coloring was carried out in baths of various compositions under various current conditions. Note that the applied voltage is alternating current. The right column of Table 1 shows the color tones obtained.

[Table] [Second Example] An anodic oxide film with a thickness of 12μ was obtained by the above-mentioned method, and this was heated at 22°C in a mixed acid bath of 5% phosphoric acid and 10% sulfuric acid, and a DC voltage of 20V was applied to the film for 50 minutes. Apply for a minute to re-anodize. Then, as shown in Table 2,
Electrolytic coloring was carried out in baths of various compositions under various current conditions. Note that the applied voltage is alternating current. The right column of Table 2 shows the color tones obtained.

【table】

[Table] [Third Example] An anodic oxide film with a thickness of 14μ was obtained by the above method, and then re-anodized by applying a DC voltage of 25V for 7 minutes in a 10% phosphoric acid bath at 22°C. Process. Next, as shown in Table 3, electrolytic coloring was carried out in baths of various compositions under various current conditions. Note that the applied voltage is alternating current. The right column of Table 3 shows the color tones obtained.

[Table] As is clear from the first to third examples above, the color tone changes on a minute-by-minute basis. Therefore, control to obtain a desired color tone is easy. In particular, as shown in each table, blue-based color tones, which are in high demand, can be obtained easily and favorably. [Comparative Example] The method described in JP-A-53-22834 is used.
That is, after anodizing the aluminum material in a 15% sulfuric acid bath to form an anodized film, 120 g of phosphoric acid,
Anodic treatment was performed in a bath of 15 g of sulfuric acid at 20 V for 6 minutes at room temperature, and then the counter electrode was applied as shown in Figure 6.
In an electrolytic bath 40 containing 1 dm2 of carbon 41,
Perform AC processing. The composition of the electrolytic bath 40 is tartaric acid
20g, 25g of nickel sulfate, 4g of stannous sulfate, 15g of magnesium sulfate, and the conditions were PH7 and 22℃.
It is. The aluminum material 42 has a U-shape of 2 dm ² as shown in FIG. energizing conditions,
Table 4 shows the color tones of the front side a and back side b of the aluminum material 42 obtained thereby.

[Table] [Fourth Example] Using the same counter electrode 41 and aluminum material 42 as in Fig. 6, aluminum sulfate and nickel sulfate were
An alternating current voltage of 20 V was applied for 2 minutes and 5 minutes in an electrolytic coloring bath 40 having a composition of 0.1 mol/mol. At 2 minutes, the color is a bluish gray, and at 5 minutes, the color is blue.
A uniform color tone was obtained on both sides a and b of the aluminum material 42. As is clear from the comparative example and the fourth example, in the comparative example, the color tone is different between the a side of the aluminum material 42 where the current flows easily and the b side where the current flows easily, but in the fourth example have the same color tone. That is, according to the method of the present invention, the throwing power is also improved.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing an aluminum anodized film according to the method of the present invention, Fig. 2 is a schematic cross-sectional view showing an aluminum anodized film subjected to re-anodizing treatment, and Fig. 3 is a colored aluminum anode. A schematic cross-sectional view showing an oxide film, FIG. 4 is a schematic front view showing a hanging tool used in electrolytic treatment, FIG. 5 is a view taken in the direction of the V arrow in FIG. 4, and FIG. Schematic cross-sectional diagrams showing the coloring bath, Figures 7 and 8
Each figure is a schematic cross-sectional view showing an aluminum anodic oxide film colored by a conventional method. 1
...Aluminum anodic oxide film, 2...pores, 3...(precipitated) metal.

Claims (1)

[Claims] 1 After re-anodizing the aluminum anodized film in an electrolyte of phosphoric acid, pyrophosphoric acid, sulfuric acid, or a mixed acid of these, Al salt, Ti salt, Mg salt, Ba
salt, one or more kinds of salts among Ca salts, and Ni salts,
Coloring of an aluminum anodic oxide film characterized by AC electrolytic treatment in an electrolytic coloring bath containing only one or more salts among Co salt, Zn salt, Fe salt, Sn salt, Cu salt, and Ag salt. Method.