JP2001329397A - Coloration method for aluminum and aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coloration method for aluminum and aluminum alloy which is capable of coloring the surface of the aluminum and aluminum alloy material to blue having the feel of a material and gray having the feel of a material. SOLUTION: This coloration method for the aluminum and aluminum alloy consists in subjecting the aluminum and aluminum alloy material to anodic oxidation treatment and subjecting the material to intermediate electrolytic treatment to electrolytically treat the material in a bath mainly composed of an organic acid or inorganic acid these salts, then to electrolytic coloring treatment in a bath containing a metallic salt, followed by electrodeposition coating by a coating material containing white pigments of 0.6 to 2.4 wt.% by the weight of the resin solid component and 0.04 to 0.24 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 and aluminum alloys, and more particularly, to a method for industrially obtaining a textured blue and a textured gray color tone.

[0002]

2. Description of the Related Art Generally, an intermediate electrolytic solution is obtained by anodizing aluminum and an aluminum alloy (hereinafter simply referred to as "aluminum") and then electrolytically treating the material in a bath mainly containing an organic acid or an inorganic acid or a salt thereof. Process,
Next, it is known that the surface is colored (tertiary electrolytic coloring) by electrolytic coloring in a bath containing a metal salt. In this conventional tertiary electrolytic coloring, a color tone based on blue or gray can be obtained.

[0003]

However, in the above-mentioned tertiary electrolytic coloring of the aluminum material, a color tone based on blue or gray can be obtained, but the color obtained by electrolytic coloring is limited. Even with gray, it was not possible to obtain textured blue or textured gray. That is, it was not possible to obtain a color having an L * value of 40 to 50, an a * value of -2 to 0, and a b * value of -6 to -2 even in blue and gray.

Accordingly, an object of the present invention is to provide a method for coloring aluminum and aluminum alloys which can color the surface of aluminum and aluminum alloy materials to textured blue and textured gray.

[0005]

According to the present invention, there is provided an intermediate electrolytic treatment in which aluminum and an aluminum alloy material are subjected to anodizing treatment and then electrolytically treated in a bath mainly containing an organic acid or an inorganic acid or a salt thereof. And then subjected to an electrolytic coloring treatment in a bath containing a metal salt, followed by 0.6 to 2.4% by weight of a white pigment based on the resin solid content, and 0.04 to 0.2% by weight.
It is characterized by applying an electrodeposition coating with a paint containing 4% by weight of a black pigment.

As the aluminum material, a pure aluminum-based material such as JISA1100, and an aluminum alloy containing magnesium and silicon in addition to aluminum such as JISA6063 are used. The shape and the like are not particularly limited, and an extruded shape such as a plate or a tube can be used. The aluminum material is preferably subjected to a pretreatment such as degreasing. Anodizing treatment is
An aluminum film is used as an anode in an acidic bath and a current is passed through the bath to form an oxide film on the aluminum surface. As the acidic bath, an acidic bath such as sulfuric acid, oxalic acid, chromic acid, or an organic acid can be used. The intermediate electrolytic treatment changes the properties of the anodic oxide film. AC, DC or AC / DC superimposed current is used in the intermediate electrolytic treatment. Particularly when AC is used, the change in characteristics applied to the anodic oxide film can be increased as compared with DC. The liquid composition of the processing bath used at this time is-
An organic acid containing an OH group or a -COOH group, phosphorous acid, sulfuric acid amide, sulfuric acid having a high concentration of 40 v / v% or more, or a salt mainly containing one or more of these salts, and As a specific example, malic acid, gluconic acid, maleic acid, citric acid, malonic acid, tartaric acid, cresol sulfonic acid, phenolsulfonic acid, sulfophthalic acid, sulfosalicylic acid, gallic acid, benzoic acid, phthalic acid, phenolic acid and the like are used. be able to. The electrolytic coloring process
Electrolysis is performed in a bath in which a metal salt is dissolved, and a metal or a metal compound is precipitated on the film to be colored.As the metal salt, nickel sulfate is used, but it is not particularly limited thereto. . The electrolysis is performed by passing an alternating current, a direct current or a pulse current between the object to be processed and a counter electrode such as a nickel plate or a styrene steel plate. In the electrodeposition coating, there is no particular limitation on the coating conditions and the type of paint, for example, acrylic melamine resin, epoxy ester resin, polybutadiene resin or the like resin, and the resin solids in the paint On the other hand, a translucent gray glossy or matte paint containing 0.6 to 2.4% by weight of a white pigment and 0.04 to 0.24% by weight of a black pigment can be used. 0.6 ~ concentration of white pigment
The reason why the content is set to 2.4% by weight is that if the content is less than 0.6% by weight, a paint feeling close to that of a transparent coating is obtained, and the change in color tone of the undercoat cannot be covered. This is because the shielding property by the coating film becomes strong and the white color becomes too strong. As the white pigment, the material is not particularly limited, for example, titanium dioxide, zinc oxide,
Antimony oxide or the like is used. 0.04 to black pigment
The content of 0.24% by weight means that if the content is less than 0.04% by weight, the effect of the white pigment is too strong. This is because it becomes difficult to obtain a gray color tone. The material of the black pigment is not particularly limited, and for example, carbon black, acetylene black and the like are used.
The thickness of the electrodeposition coating film is not particularly limited.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. First, Embodiment 1 will be described. Extruded aluminum alloy A6063S-T5 (JIS) at 20 ° C
After immersion in a 5% nitric acid aqueous solution for 5 minutes to perform a degreasing treatment, the substrate was immersed in a sodium hydroxide aqueous solution at a bath temperature of 50 ° C. for 8 minutes to perform an etching treatment. Then, at 20 ° C
Was immersed in a 5% aqueous solution of nitric acid for 2 minutes to remove smut.
Next, an anodic oxidation treatment was performed on the object to be treated which had been subjected to the above pretreatment. In the anodic oxidation treatment, a current density of 100 A / m ² was set in a sulfuric acid aqueous solution (150 g / L) at a bath temperature of 20 ° C.
An anodic oxidation treatment was performed for 0 minutes to form an anodic oxide film having a film thickness of 9 μm (primary treatment). Subsequently, an intermediate electrolytic treatment was performed on the object after the primary treatment described above. In this intermediate electrolytic treatment, an aqueous solution of phosphorous acid at a bath temperature of 20 ° C. (150 g /
In L), an intermediate electrolytic treatment was performed at a current density of 40 A / m ² for 2 minutes (secondary treatment). Next, the object after the secondary treatment was used as a cathode, and an AC voltage of 40 V was applied in an aqueous solution containing nickel sulfate (100 g / L), sulfamic acid (20 g / L), and tartaric acid (5 g / L). An electrolytic coloring treatment was performed (tertiary treatment). Thereafter, a sealing treatment was performed. Further, the substrate was immersed in ion-exchanged water having a bath temperature of 80 ° C. and a conductivity of 50,000 Ω · cm for 10 minutes, washed with hot water, and then naturally dried. In this way, the object to be processed was subjected to electrolytic coloring (tertiary electrolytic coloring) to obtain an object having a color tone of 50.18 in L * value, -1.72 in a * value, and -8.09 in b * value. The workpiece was electrodeposited.
For the electrodeposition coating, a paint containing 0.96% by weight of a white pigment and 0.08% by weight of a black pigment based on the resin fixed component was used. The object to be processed obtained by the electrodeposition coating was baked. The baking is 19
Performed at 0 ° C. for 30 minutes. As a result, the L * value was 44.6.
2. A color tone with an a * value of -0.76 and a b * value of -5.32 could be obtained.

Next, Embodiments 2 to 6 will be described. In Embodiments 2 to 6, in the above-described Embodiment 1, the intermediate electrolysis treatment time was changed to obtain an electrolytic coloring treatment. The color tone was changed variously. The relationship between the intermediate electrolytic treatment time, the color tone after the electrolytic coloring treatment, and the color tone after the electrodeposition coating in Examples 1 to 6 is shown in Table 1 below, and the color tone after the electrolytic coloring treatment and the electrodeposition coating are shown. FIG. 1 shows the relationship with the later color tone.

[0009]

[Table 1]

As apparent from Table 1 and FIG. 1, the color tone obtained after electrolytic coloring has an L * value of 50.03 to 51.7.
0, a * value -0.04 to -2.58, b * value -1.60
-8.09. That is, as shown in FIG. 1, the color tone was in the range outside the region A indicated by the one-dot chain line. In contrast, the color tone obtained after the electrodeposition coating had an L * value of 44.
34 to 45.00, a * value -0.33 to -1.23, b
* Value -2.35 to -5.32. That is, as shown in FIG. 1, the color tone was in the range inside the region A indicated by the dashed line. In Examples 1 to 6 described above, the L * value was 4
Blue and gray in the range of 0 to 50, a * value of −2 to 0, and b * value of −6 to −2 were obtained. In FIG. 1, the range of the a * value of −2 to 0 and the range of the b * value of −6 to −2 are the range of the region A indicated by the one-dot chain line. That is, in the conventional electrolytic coloring, the L * value was larger than 50, and the a * value and the b * value were in the range outside the region A shown in FIG. Further, by performing electrodeposition coating using a paint containing a predetermined pigment, L * value is 40 to 50 and a * value and b * value are obtained in a color range in the range inside the region shown in FIG. As a result, it was possible to obtain a textured blue and a textured gray which could not be obtained conventionally.

[0011]

According to the present invention, aluminum and an aluminum alloy can be colored into a textured blue and a textured gray.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a color tone obtained after electrolytic coloring and a color tone obtained after electrodeposition coating in an example of the present invention.

Claims (1)

[Claims] 1. An aluminum and aluminum alloy material is subjected to anodizing treatment, and then subjected to an intermediate electrolytic treatment for electrolytic treatment in a bath mainly containing an organic acid or an inorganic acid or a salt thereof, and then containing a metal salt. After electrolytically coloring in a bath, electrodeposition with a paint containing 0.6 to 2.4% by weight of a white pigment and 0.04 to 0.24% by weight of a black pigment with respect to the resin solid content. A method for coloring aluminum and aluminum alloys, characterized by applying a coating.