JPH11106994A - Method for forming colored film of aluminum or aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a colored film by which an electrolytically colored film formed on the surface of an aluminum-base material is colored in an achromatic gray color of a desired variable density from light gray to dark gray in accordance with the brightness without being affected by a change in chroma. SOLUTION: An anodic oxide film formed on an aluminum or aluminum alloy substrate is electrolytically colored, as required, in the various chroma of >=30 L* value and then coated by electrodeposition with a translucent gray paint contg., based on a solid resin component, 0.7-1.2 wt.% white pigment and 0.03-0.08 wt.% black pigment.

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 aluminum or an aluminum alloy used as a material for building materials such as sashes and panels, and more particularly to a method for coloring aluminum or aluminum alloy formed on the surface of such an aluminum-based material. It is an almost achromatic gray with no reddish brown or bluish tint on the anodized film, and has various shades from light gray close to white to dark gray close to black without changing the type of paint. The present invention relates to a method for forming a colored film of aluminum and aluminum alloy which can be easily colored in gray.

[0002]

2. Description of the Related Art As a method of coloring an aluminum-based material, there is known an electrolytic coloring treatment in which an anodizing treatment is applied to a base material, and then an AC or DC electrolysis is performed in an aqueous solution containing a metal salt such as nickel, cobalt, or tin. Have been. Furthermore, in order to eliminate the color tone difference that tends to occur due to variations in metal salt concentration, current density, electrolysis time, and the like, and to color in a color that cannot be obtained only by the electrolytic coloring process, the electrodeposition process is further performed after the electrolytic coloring process. Painting is also done.

[0003] That is, Japanese Patent Application Laid-Open No. Hei 8-246191 discloses that an anodized film which is electrolytically colored to be almost black, for example, having a lightness represented by L ^* value of 26 or less,
A method of forming a bluish-gray composite film by performing electrodeposition coating using a paint containing a white pigment is disclosed.

Japanese Patent Application Laid-Open No. 9-41194 discloses that
High-brightness gray coating by applying electrodeposition coating with clear paint containing black pigment to anodized film (silver film) that has not been subjected to electrolytic coloring treatment or anodized film that has been subjected to electrolytic coloring treatment It is disclosed that a colored aluminum material having the following formula can be obtained.

[0005]

However, among the above-mentioned conventional coloring methods, in the coloring method described in JP-A-8-246191, the underlying anodic oxide film is electrolytically colored with low brightness close to black. When the color is electrolyzed to high lightness, the color changes to the underlying color film (higher saturation), and the color changes to higher color saturation (higher saturation). Even so, there is a problem that it cannot be colored in achromatic gray. In the coloring method described in Japanese Patent Application Laid-Open No. 9-41194, when the underlying anodic oxide film has a high brightness (silver film), the color becomes gray almost achromatic, but the oxide film has a medium brightness or low brightness. In the case of electrolytic coloring with lightness, there is still a problem that it is not possible to color achromatic gray due to the effect of color change of the base, and these problems are solved. To be able to color pure gray without being affected by the color change due to electrolytic coloring, obtain an aluminum or aluminum alloy member with an achromatic gray appearance color of various shades from light gray to dark gray Had to be a challenge.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in a conventional method for forming a colored film of aluminum and an aluminum alloy. Can be colored in achromatic gray with a desired shade according to the following, for example, by using one kind of paint, to obtain a composite colored film colored in achromatic gray with various shades from light gray to dark gray It is an object of the present invention to provide a method for forming a colored film of aluminum and an aluminum alloy that can be used.

[0007]

According to a first aspect of the present invention, there is provided a method for forming a colored film of aluminum and an aluminum alloy, wherein the aluminum or aluminum alloy is subjected to anodizing treatment and then electrolytically colored. After treatment, without applying electrolytic coloring treatment,
Anodized film with optional brightness of L ^* value of 30 or more,
It is characterized in that electrodeposition coating is performed with a translucent gray paint containing 0.7 to 1.2 wt% of a white pigment and 0.03 to 0.08 wt% of a black pigment with respect to the resin solid content. The configuration of such a method of forming a colored film of aluminum and an aluminum alloy is a means for solving the above-mentioned conventional problems.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for forming a colored film of aluminum and aluminum alloy according to the present invention is, as described above, a semi-transparent anodized film which is electrolytically colored to various brightness or a silver film which is not subjected to electrolytic coloring treatment. By applying an electrodeposition coating with a gray paint, the oxide film is colored to an achromatic gray with a desired shading corresponding to its lightness. The electrolytic coloring treatment that is performed as necessary after the oxidation treatment can be performed by a conventional method that has been conventionally performed.

For example, an acidic bath such as sulfuric acid, oxalic acid, chromic acid, or an organic acid can be used as an electrolytic solution in the anodizing treatment. As for the electrolytic coloring treatment, an aqueous solution containing nickel sulfate, cobalt sulfate, copper sulfate, stannous sulfate, or the like, is used between the base material on which the anodized film is formed and the counter electrode made of a nickel plate or a stainless steel plate. , AC, DC or pulse current.

The brightness of the electrolytic coloring film in the present invention can be adjusted mainly by adjusting the energizing time during the electrolytic coloring treatment. In the method for forming a colored film according to the present invention, not performing the electrolytic coloring treatment is also included as a part of adjusting the brightness of the oxide film, and the oxide film having the highest brightness before performing the electrolytic coloring treatment (so-called silver film). By applying the electrodeposition coating directly to the composite color film, the color tone of the composite colored film after the electrodeposition coating can be made the lightest light gray.

In the method for forming a colored film of aluminum and an aluminum alloy according to the present invention, the brightness of the electrolytic colored film represented by the L ^* value must be 30 or more. This is because, when the L ^* value is less than 30, the color tone of the composite colored film after the electrodeposition coating is dominated by the colored film exhibiting almost black color, and the adjustment of the shade cannot be performed. By becoming bluish.

Electrodeposition coating uses water-based coatings, so there is no danger of fire or environmental pollution, and it has advantages such as uniform coating of coated objects having complicated shapes and high coating efficiency. The present invention is applied to the method for forming a colored film according to the present invention. However, the coating conditions and the type of paint to be used are not particularly limited. For example, acrylic melamine resin, epoxy ester resin, por ester resin, polybutadiene resin For example, a translucent gray glossy or matte paint can be used.

In this case, a specific component of the translucent gray paint is 0.7% based on the resin solid content in the paint.
To 1.2 wt% of a white pigment (for example, titanium dioxide, zinc oxide, antimony oxide, etc.) and 0.03 to 0.08
A pigment to which a black pigment (for example, carbon black, acetylene black, or the like) of wt% is simultaneously added is used.
This is because when the amount of the white pigment is less than the lower limit of 0.7 wt%, the black pigment is not less than the lower limit of 0.03 wt%, and also within the range of 0.03 to 0.08 wt%. Even at some times, the paint feel is similar to clear (transparent) paint, and the change in lightness of the undercoat appears as a change in the density of the composite colored film, but it cannot cover the color change of the undercoat. When a complex color film having a high color saturation is formed and an achromatic gray cannot be obtained, and when the amount of the white pigment exceeds the upper limit of 1.2 wt%, the black pigment becomes the upper limit of 0.08 wt. %, And even within the above range, the shielding property of the coating film is enhanced and the feeling of painting is enhanced, the color tone of the coating material becomes dominant, and the color tone of the underlying coating film changes due to the change in lightness of the underlying film. Light and dark varieties Deployment due to the fact that is difficult to obtain.

Further, the lower limit of the addition amount of the black pigment is 0.03.
wt%, the white pigment has an upper limit of 1.2 w
The color tone of the composite colored film is governed by the white pigment in the paint, even when the content exceeds 0.7%, and even when the content is within the range of 0.7 to 1.2% by weight. Conversely, when the amount of the black pigment added exceeds the upper limit of 0.08 wt%, the white pigment becomes 0.7%.
In addition to the case where the amount is less than 0.1 wt%, even when the amount is within the above range, a complex color film having a high saturation due to the influence of the base color cannot be obtained, and an achromatic gray cannot be obtained. This is because it is dominated by black pigments, and it is not possible to obtain light-gray side shading variations.

The thickness of the electrodeposited coating film made of the above-mentioned coating material is preferably 5 to 25 from the viewpoint of the coating appearance and the workability of coating.
μm is desirable.

[0016]

In the method for forming a colored film of aluminum and an aluminum alloy according to the present invention, the anodized film formed on the aluminum or the aluminum alloy is subjected to an electrolytic coloring treatment as required to obtain an L ^*.
After the brightness represented by the value is any brightness of 30 or more,
Electrodeposition coating with a translucent gray paint containing 0.7 to 1.2 wt% of a white pigment and 0.03 to 0.08 wt% of a black pigment with respect to the resin solid content,
Since this translucent gray electrodeposition paint has a suitable translucency and shielding properties, the light and darkness of the oxide film and the translucent gray color of the electrodeposition coating film combine to form an electrodeposition paint. The oxide film is colored in various shades of gray ranging from light gray to dark gray in accordance with the change in the lightness by one kind of paint without changing the lightness. Also, at this time, even if the oxide film is electrolytically colored to a high saturation with a red, blue, or yellow tint, the color change is concealed by the translucent gray electrodeposition coating film having a suitable shielding property, and the low It will be colored achromatic gray with saturation.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

According to JIS H 4100, A6063S-
Extruded aluminum alloy material defined as T5
After being degreased and washed by immersion in a 5% nitric acid aqueous solution maintained at 50 ° C. for 5 minutes, the substrate was immersed in an aqueous sodium hydroxide solution (50 g / L) maintained at 50 ° C. for 8 minutes to perform etching. After that, it was immersed in a 5% aqueous solution of nitric acid at 20 ° C. for 2 minutes to remove the smut.

Next, the extruded material is subjected to an anodic oxidation treatment in a sulfuric acid aqueous solution (150 g / L) at 20 ° C. at a current density of 100 A / m ² for 35 minutes to form an anodic oxide film having a thickness of 9 μm. I let it.

The extruded member having the anodic oxide film formed thereon is connected to a cathode and subjected to electrolytic coloring by applying a voltage of 25 V in an aqueous solution containing 100 g / L of nickel sulfate and 40 g / L of boric acid. By adjusting the time, the color is adjusted to 7 levels of lightness of stainless color, dark stainless steel, light bronze, bronze, dark bronze, black bronze, and black. A profile provided with an oxide film having a level of lightness was prepared. These extruded profiles have an additional 5
After a hot water washing treatment at 78 ° C. for 10 minutes with ion-exchanged water having a conductivity of 0000 Ω · cm, it was air-dried and used in the following Examples and Comparative Examples.

Table 1 shows the lightness L ^* , chromaticity a ^* , b ^* , and chroma C ^* of these eight types of oxide films. In addition,
a ^*, b ^* represents the direction of the respective colors, red increases as the a ^* value is on the positive side, shows that the green is strong enough becomes negative, as a plus side for the b ^* value yellow It indicates that the taste increases and the blueness increases as the value decreases. That is, as the a ^* value and the b ^* value are closer to zero, the saturation C ^* becomes smaller, indicating a pure achromatic color that does not take on colors such as red, blue, and yellow.

The intended achromatic gray in the method for forming a colored film of aluminum and aluminum alloy according to the present invention is one having a chroma represented by a C ^* value of 4 or less.

[0023]

[Table 1]

[0024] Among the extruded profile of the eight kinds shown in Example Table 1, L ^* extrusions 6 species lightness with more than 30 oxide film represented by a connected to the anode, the resin solids 0.92 wt% of the white pigment (0.077 wt% of the diluted paint as a whole when diluted and stored in the electrodeposition tank) and 0.05 wt%
% Black pigment (also 0.004 wt% for diluted paint)
%) And dipped in an acrylic melamine resin-based matte electrodeposition paint maintained at a liquid temperature of 20 ° C.
After energizing for 3 minutes by applying a voltage of 0 V, washing with water and baking and drying in a furnace at 170 ° C. for 25 minutes were performed to obtain composite colored films each having an electrodeposition coating film of 18 μm.

Table 2 shows the results of measuring the color tone of the composite colored film thus obtained.

[0026]

[Table 2]

Comparative Example 1 Of the eight types of extruded profiles shown in Table 1, two extruded profiles provided with a low-brightness oxide film whose lightness represented by L ^* was less than 30 Using the same electrodeposition paint, applying an electrodeposition coating under the same conditions, and baking and drying in the same manner to obtain a composite coloring film having an electrodeposition coating film of 18 μm, and then obtaining the composite coloring film. The color tone of the film was measured. Table 3 shows the results.

[0028]

[Table 3]

COMPARATIVE EXAMPLE 2 Eight types of extruded members shown in Table 1 were prepared by adding 0.64 wt% of a white pigment to a resin solid content (when diluted and stored in an electrodeposition tank, 0.052wt
%) Containing immersion in an acrylic melamine resin matte electrodeposition paint at a liquid temperature of 20 ° C., connected to the anode, and subjected to electrodeposition coating under the same conditions as in the example, and then baked and dried similarly. As a result, a composite colored coating having an electrodeposition coating of 18 μm was obtained. Table 4 shows the results of measuring the color tone of the composite colored film thus obtained.

[0030]

[Table 4]

COMPARATIVE EXAMPLE 3 Eight types of extruded profiles shown in Table 1 were applied to a 0.26 wt% black pigment based on the resin solid content (when diluted and stored in an electrodeposition tank, the diluted paint was 0.022wt
%) Containing immersion in an acrylic melamine resin matte electrodeposition paint at a liquid temperature of 20 ° C., connected to the anode, and subjected to electrodeposition coating under the same conditions as in the example, and then baked and dried similarly. As a result, a composite colored coating having an electrodeposition coating of 18 μm was obtained. Table 5 shows the results of measuring the color tone of the composite colored film thus obtained.

[0032]

[Table 5]

As a result, in the embodiment in which the anodic oxide film having a lightness of L ^* value of 30 or more is electrodeposited with a translucent gray paint containing a white pigment and a black pigment, As is clear from FIG. 1, which shows the relationship between the saturation and the saturation of the composite colored film after the electrodeposition coating, regardless of the color tone of the underlying oxide film, the anodic oxide film becomes highly saturated by electrolytic coloring. It was confirmed that even when colored, a color tone with low saturation could be obtained, and that an achromatic gray composite colored film having a shading variation corresponding to the lightness of the underlying oxide film was obtained.

On the other hand, even when the same translucent gray paint as that of the embodiment was used, the electrodeposition coating was applied to the oxide film colored almost in black with a lightness represented by L ^* value of less than 30 and almost black. In the case of Comparative Example 1 performed, despite the difference in brightness between the colored oxide films, the difference in brightness does not appear in the composite colored film after the electrodeposition coating, and the shading cannot be adjusted.
It has been found that the composite colored film has a bluish color tone and achromatic gray cannot be obtained.

Further, in Comparative Example 2 in which the electrodeposition coating was performed using a translucent paint containing only a white pigment, the electrodeposition coating film had a certain degree of shielding properties, and the color saturation of the underlying colored film was relatively low. Although it can sometimes cover the change in saturation, it cannot be covered when the saturation of the underlying colored film is high, and a constant achromatic gray shade variation cannot be obtained. In Comparative Example 3, as can be seen from FIG. 1, the color tone of the composite colored film after electrodeposition coating was greatly affected by the saturation of the underlying colored film, and the change in the saturation of the underlying colored film was almost unchanged. , And it was confirmed that almost no achromatic gray composite colored film could be obtained except for a silver film not subjected to electrolytic coloring.

[0036]

As described above, the method for forming a colored film of aluminum and an aluminum alloy according to the present invention can be carried out by performing an electrolytic coloring process if necessary.
^{* The} lightness represented by the value is to apply an electrodeposition coating with a translucent gray paint with a predetermined amount of white pigment and black pigment added to the anodic oxide film with any lightness of 30 or more,
By simply coloring the anodic oxide film to various brightnesses by adjusting the electrolytic coloring conditions, it is easy to obtain an achromatic gray composite colored film with shading variations according to the brightness change of the oxide film without changing the electrodeposition paint. Since the process can be simplified and the need for providing many electrodeposition coating tanks is eliminated, equipment costs and management costs can be reduced, and aluminum and aluminum having such a composite colored film can be used. An extremely excellent effect that an alloy member can be manufactured at low cost is brought about.

[Brief description of the drawings]

FIG. 1 shows the effect of the oxide film saturation before electrodeposition coating on the saturation of a composite colored film by the method for forming a colored film of aluminum and aluminum alloy according to the present invention, in comparison with comparative examples having different electrodeposition paint components. It is a graph shown.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuo Sakashita 70 Hayakawa, Takaoka City, Toyama Prefecture Inside Sankyo Aluminum Industries Co., Ltd. (72) Inventor Koji Noda 70 Hayakawa, Takaoka-shi, Toyama Prefecture Sankyo Aluminum Industry Co., Ltd.

Claims (1)

[Claims] 1. An aluminum or aluminum alloy is subjected to anodizing treatment and then subjected to electrolytic coloring treatment, or is subjected to anodizing treatment and then subjected to electrolytic coloring treatment.
^* Semi-transparent containing 0.7 to 1.2 wt% white pigment and 0.03 to 0.08 wt% black pigment with respect to the resin solid content in the anodic oxide film having an arbitrary brightness of 30 or more. A method for forming a colored film of aluminum and an aluminum alloy, comprising applying an electrodeposition coating with a gray paint.