JP2938781B2 - Method of forming blue-gray composite film on aluminum material and aluminum alloy material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a blue-gray composite film on an aluminum material and an aluminum alloy material. In particular, it is used for the production of building materials and exterior products.

[0002]

2. Description of the Related Art For example, building materials such as curtain walls, building interior and exterior materials, and exterior products such as gates and fences produced from aluminum materials or aluminum alloy materials (hereinafter, abbreviated as "aluminum materials"). With the spread and spread of the color tone, diversification of the color tone is strongly demanded.

[0003] As a method for coloring an aluminum material, for example, an alloy coloring method, an electrolytic coloring method, and the like are known, and various chromatic colors can be selectively colored. However, since individualization and diversification do not stop, the demand for achromatic colors has increased.

As a coloring method using an achromatic color as a target color,
Alloy coloring method (Japanese Patent Application Laid-Open No. 2-254129), secondary electrolysis method (Japanese Patent Application Laid-Open No. 61-143593), coating method, anodizing treatment method utilizing current recovery phenomenon (Japanese Patent Application Laid-Open No. 1-221796).
No. 3), a method of obtaining a composite film by applying an electrodeposition coating containing a chromatic pigment on a bronze-colored anodic oxide film
No. 3798) is known.

Here, the practical productivity such as anodic oxide film thickness control, bath stability, etc. is compared and evaluated.
The method for forming a composite film disclosed in JP-A-183798 is presumed to be superior. In this method, an aluminum material is subjected to anodizing treatment, then is colored in a bronze color by electrolytic coloring, and then a gray-tone composite film is obtained by electrodeposition coating containing a chromatic pigment.

[0006] Among the gray tones, light gray, gray, dark gray, dark grayish,
Includes grayish. However, since the electrolytic coloring film is light bronze, bronze, or dark bronze, the color is reddish gray or yellowish gray. That is, C
According to the IE-1976 (L ^* , a ^* , b ^* ) color space color system, the indices a ^* , b ^* are both on the positive (+) side, and their absolute values are "1 or less" which is called an achromatic color. "(For example," 4.6 "). In other words, this is a method of obtaining a gray-based chromatic color in which red or yellow is felt relatively strong.

[0007] In Comparative Example 2 described in the above publication, from page 7, upper right column, line 13 to line 4, lower left column, line 4, a bronze-colored electrolytic colored film was formed on an aluminum material. It is specified that when a coating film was formed in an electrodeposition coating liquid containing a blue pigment, a blue-based composite film was obtained, and a gray-based composite film could not be obtained. The use of blue pigment seems to be a natural result. For example, if a red pigment is used, the color becomes red.

[0008]

As described above, even if a gray chromatic color can be obtained by any of the above-mentioned conventional methods, an achromatic color (absolute value of the indices a ^* and b ^* of 1 or less) can be obtained. Gray) cannot be obtained.

Here, a tertiary electrolytic coloring method (Japanese Patent Application Laid-Open No.
According to No. 2834), it was confirmed that a bluish gray color was obtained. The average technician and the general consumer in the construction industry were given several samples with different lightness (L ^* ) between the blue-gray color and the achromatic color (gray) applied to the aluminum material by the spray coating method. According to the results of marketing to the target, the bluish gray color was overwhelmingly favored over the completely achromatic color. Also, in comparison with conventional chromatic colors other than blue based on the above publications, the novelty and the superiority or hobby from the viewpoint of novelty and mass color or stable color are supported.

However, the tertiary electrolytic coloring method is very unstable and reproducible because the color tone changes due to a slight structural change relating to the thickness and quality of the anodic oxide film because of the use of light interference. As a result, the problem of low yield remains, which results in high costs and slow production.

The present invention has been made in view of the above circumstances, and has as its object to provide an aluminum material and an aluminum alloy capable of forming a blue-gray composite film stably, with high reproducibility and at low cost. An object of the present invention is to provide a method for forming a blue-gray composite film of a material.

[0012]

When the formation of an achromatic composite film is taken into consideration, for example, it is extremely difficult to achieve achromatic color using a bronze-based chromatic color as a base. Here, since the achromatic color has only lightness, the applicant conducted a test study on a combination of black and white based on the general tone principle.

That is, the aluminum material 1 shown in FIG. 1 is anodized to form an anodic oxide film 10.
0 is colored black. Here, the black range is CIE-
When the value of L ^{* in} the 1976 (L ^* , a ^* , b ^* ) color space color system is 2
It is preferably 6 or less. This is based on the relationship with the white coating film 30 described later.
As a coloring method, an electrolytic treatment is performed in an electrolytic coloring bath containing a metal salt such as Ni, Co, Sn, and Cu to deposit a large amount of the metal salt 20 in the micropores 11 of the anodic oxide film 10 to obtain a black color. An electrolytic coloring method and a dyeing method of coloring black using a black dye were tried, but the former was selected as an advantage in terms of cost, quality, and production.

On the basis of this selection, the validity of the anodic oxidation treatment was examined, and each anodic oxidation treatment was carried out in an aqueous solution of a mineral acid such as sulfuric acid and phosphoric acid, an organic acid such as oxalic acid and sulfosalicylic acid, or a mixed acid thereof by an ordinary method. When the treatment was performed, there was no difference in performing the subsequent electrolytic coloring step. However, it was confirmed that the thickness of the anodic oxide film 10 was appropriately set to 6 to 15 μm for black electrolytic coloring.

Next, as a method of applying a white paint to the black anodic oxide film (10, 20), there is an electrostatic coating, a dip coating or an electrodeposition coating.
Electrodeposition coating was selected as advantageous from the viewpoint of productivity.

The white pigment constituting the electrodeposition solution composition for the electrodeposition coating may be a white inorganic pigment such as titanium white, lead white or zinc white, or a white ceramic such as alumina, zirconia or boron nitride. Used. The white pigment 31 is preferably kneaded with a varnish and a surfactant to improve dispersibility in an electrodeposition bath. In addition, the concentration of the white pigment 31 is 0.1.
When the content is less than this range, the white coating film 30 cannot be obtained with the thickness of the practical coating film, and when it is more than this range, the transparent white coating film 30 cannot be obtained. Preferably, 0.
The range of 0.05 to 0.3 w% is good.

Further, the particle size of the white pigment 31 is 0.5
10 to 10 μm is appropriate. If the particle size is too small, coating 3
Not only is whitening inferior to 0 but a white pigment 31 having a specified concentration or more is required, but also the dispersibility of the white pigment deteriorates and the corrosion resistance of the coating film deteriorates. Conversely, if the particle size is too large, the sedimentation of the white pigment is accelerated, causing a problem in bath stability.
The resin component is composed of an acrylic resin or a fluorine resin and a melamine resin, and the heating residue is adjusted to a range of 5 to 15 w% before use.

The conditions of the electrodeposition coating treatment are as follows: bath temperature 15 to 25 ° C.
DC voltage of 100 to 300 V is applied using black anodized aluminum as an anode. Thereby, the white coating film 30 having a coating film thickness of 6 to 30 μm and capable of seeing through the base can be formed. When the coating film thickness is large, a gray color with high lightness is obtained, and when the film thickness is small, a gray color with low lightness is obtained. Thus, the brightness of the bluish gray can be controlled by adjusting the thickness of the coating film. Further, the brightness can be adjusted by adjusting the concentration of the white pigment 31.

The black anodic oxide film (10, 20)
Before electrodeposition coating, it is preferable to perform washing (hot water washing) for removing miscellaneous ions in warm water at about 70 ° C. Further, after the electrodeposition coating process, it is preferable to remove the non-precipitated white pigment 31 and the resin component by a water washing process. Finally, this is 150-25
The coating is baked and dried in an atmosphere of 0 ° C.

Here, the combination of the anodic oxidation treatment, the black electrolytic coloring treatment, and the white electrodeposition coating treatment using the white pigment 31 causes the lightness index L ^{* to} be, for example, 30 to 42 and the red to green index a ^{* to} be green. (For example, -0.5 to -1.0) and yellow to
A blue-gray composite film having a blue index b ^* with a blue tendency (for example, -1.2 to -3.5) can be formed. In other words, a bluish gray color as close as possible to an achromatic color can be obtained. The gloss of the composite film can also be adjusted by changing the resin component of the electrodeposition paint to a high gloss type or a low gloss type.

That is, the method of forming a blue-gray composite film of an aluminum material and an aluminum alloy material according to the present invention comprises subjecting an aluminum material or an aluminum alloy material to an anodic oxidation treatment to form an anodic oxide film, followed by electrolytic coloring. The anodic oxide film is colored black by applying a treatment, and then subjected to an electrolytic treatment in an electrodeposition coating solution containing a white pigment having a particle size of 0.5 to 10 μm and 0.01 to 0.5 w% to give a black color. A white coating film on which the black anodic oxide film can be seen is formed on the anodic acid coating film.

[0022]

In the case of the present invention having the above structure, an aluminum material is subjected to anodizing treatment to form a positive oxide film. Next, an anodic oxide film is colored black by performing an electrolytic coloring treatment. Furthermore, a particle size of 0.5-10
An electrolytic treatment is performed in an electrodeposition coating solution containing 0.01 to 0.5 w% of a white pigment at μm to form a transparent white coating film on the black anodic oxide coating.

In the composite coating thus obtained, part of the daylight A shown in FIG. 1 is reflected on the surface of the outermost white coating 30. The gloss is determined by the amount of reflected light B1. Then
The other part is dispersed in the coating film and reflected by the white pigment 31 (B
2) The appearance is white. Further, the remaining part is the metal 2 deposited in the micropores 11 of the anodic oxide film 10.
The light is reflected (B3) on the surface of No. 0 and has a black color appearance. There is also a small amount of reflected light (B4) from the aluminum material 1.

Thus, if the reflected light from the composite film reflects the entire spectrum of daylight A, it becomes an achromatic gray color. The relationship between the particle diameter of the white pigment 31 and the spectrum of the daylight low wavelength part is mainly. From a slightly bluish gray color.

The lightness of the bluish gray color is determined by the ratio of the amount of reflected light between the black film (10, 20) and the white film 30. Therefore, the white pigment 31 in the white coating 30
Is large, the amount of light reflected from the black film (10, 20) is small, so that the brightness is high.

[0026]

Embodiments of the present invention will be described below. (Example 1) After aluminum material, that is, extruded aluminum material (A6063) is subjected to ordinary pretreatment, 150 g /
In a 1-H ₂ SO ₄ aqueous solution at 20 ° C.
Anodizing treatment was performed for 30 minutes at m ² to form an anodized film of 10 μm. Next, stannous sulfate was added at 10 g /
An electrolytic treatment was performed for 10 minutes by applying an alternating current of 15 V in the contained electrolytic coloring liquid to obtain a black anodic oxide film having an L ^* value of "26" or less. Next, a direct current of 180 V is applied in an electrodeposition coating solution containing 0.1 w% of titanium white having a resin solid content of 10 w% and a particle diameter of 5 μm to perform an electrolytic treatment for 2 minutes.
A μm electrodeposited film was formed. Finally, baking and drying were performed at 180 ° C. for 30 minutes to obtain a bluish gray and glossy composite film.

This was measured using a colorimeter (CR200 manufactured by Minolta).
Color), the following results were obtained. L ^* = 35.2 a ^* =-0.9 b ^* =-1.7

Here, the red-green index a ^* is "-" of the green tendency.
0.9 "and within the achromatic (" 1 or less ") range, and the yellow-blue index b ^* is" -1.7 "which slightly deviates from the achromatic (" 1 or less ") range. It is understood to be an excellent bluish gray color as close as possible to an achromatic color.

Further, as compared with the gray bronze color shown in the following (Comparative Example 2), it has a new color tone full of mass and is settled down, and also has excellent corrosion resistance and weather resistance as a composite film. Was confirmed. In addition, 5
Even if it was repeated 0 times, the same bluish gray color could be obtained with high stability and high reproducibility.

Second Embodiment Aluminum plate (A110)
0) after the by usual pretreatment, 150g / 1-H ₂ S
Anodizing treatment was performed in an O ₄ aqueous solution at 20 ° C. and a current density of 120 A / m ² for 45 minutes to form a 15 μm thick anodic oxide film thicker than in the first embodiment. Then, an alternating current of 1 g in an electrolytic coloring liquid containing 100 g / 1 of nickel sulfate.
6 V was applied and electrolysis was performed for 10 minutes to obtain a black anodic oxide film having an L ^* value of "26" or less. Then, the microgel type resin solid content is 10 w%, and the particle size is 5 μm.
0.2w% of 1-10μm alumina with maximum distribution
A direct current of 180 V was applied in the contained electrodeposition coating solution to carry out an electrolytic treatment for 2 minutes to form an electrodeposition coating film of 15 μm. Finally, baking and drying were performed at 180 ° C. for 30 minutes to obtain a bluish gray, low gloss composite film.

The color was measured with the same colorimeter, and the following results were obtained. L ^* = 31.2, a ^* =-0.5 b ^* =-2.7

Compared with the case of the first embodiment, since the thickness of the anodic oxide film was increased (15 μm) and the content of white alumina in the electrodeposition coating liquid was increased to 0.2 w%, The blue index b ^* was "-2.7", which further increased the bluish tint.

(Third Embodiment) Extruded aluminum material (A
6063) was subjected to the usual pretreatment, and then 150 g / 1-
20 ° C. in an aqueous solution of H ₂ SO ₄ and a current density of 120 A / m ²
For 30 minutes to form an anodized film having a thickness of 10 μm. Then, an electrolytic treatment was performed for 10 minutes by applying an alternating current of 15 V in an electrolytic coloring liquid containing 10 g / 1 of stannous sulfate to obtain a black anodic oxide film similar to that of the first embodiment. Next, a resin solid content of 10 w% and a particle diameter of 5 μm
DC 1 in an electrodeposition coating solution containing 0.1% by weight of titanium white
An electrolytic treatment was performed by applying 80 V for 3 minutes to form an electrodeposited film having a thickness of 20 μm thicker than that in the first embodiment. Finally, baking and drying were performed at 180 ° C. for 30 minutes to obtain a bluish gray and glossy composite film.

The color was measured with the same colorimeter, and the following results were obtained. L ^* = 41.9, a ^* =-1.0 b ^* =-3.5

Here, by increasing the thickness of the white coating film as compared with the case of the first embodiment, the index b ^* becomes "-3.
In the case of 5, a gray color in which the bluish color was further emphasized could be obtained.

(Comparative Example 1) Extruded aluminum material (A6
063) was subjected to the usual pretreatment, and then 150 g / 1-H
Anodizing treatment was performed in a ₂ SO ₄ aqueous solution at 20 ° C. and a current density of 120 A / m ² for 30 minutes to form an anodized film of 10 μm. Next, nickel sulfate was added at 100 g / 1.
In the contained electrolytic coloring liquid, an alternating current of 16 V was applied and an electrolytic treatment was performed for 10 minutes to obtain a black anodic oxide film having an L ^* value of "26" or less. Next, a direct current of 180 V is applied in an electrodeposition coating solution containing 0.5 w% of alumina having a resin solid content of 10 w% and a particle diameter of 0.05 μm, and subjected to an electrolytic treatment for 3 minutes. Was formed. Finally, 180 ° C
Was performed for 30 minutes to obtain a glossy composite film very similar to black rather than gray.

The color was measured with the same colorimeter, and the following results were obtained. L ^* = 27.1, a ^* = 0.05 b ^* = − 0.29

Therefore, the white pigment (alumina) is
As in the case of the embodiment, even if the electrodeposition coating is performed for the same voltage and the same time in the electrodeposition coating liquid containing 0.5% by weight, the particle diameter is 0.5%.
If it is 0.05 μm or less, a substantial effect of the white coating film cannot be obtained. That is, although it is an achromatic color, it becomes the color of the black anodic oxide film itself, and it can be seen that a bluish gray color cannot be obtained.

Comparative Example 2 Extruded aluminum material (A6
063) was subjected to the usual pretreatment, and then 150 g / 1-H
Anodizing treatment was performed in a ₂ SO ₄ aqueous solution at 20 ° C. and a current density of 120 A / m ² for 30 minutes to form an anodized film having a thickness of 10 μm as in the first embodiment. Next, an alternating current of 15 g in an electrolytic coloring solution containing 100 g / 1 of nickel sulfate.
By applying V and performing an electrolytic treatment for 2 minutes, a bronze-colored anodic oxide film was obtained. Next, as in the case of the first embodiment, titanium white having a resin solid content of 10% by weight and a particle diameter of 5 μm was added to 0.1 wt.
In the electrodeposition coating solution containing w%, a direct current of 180 V was applied and an electrolytic treatment was performed for 2 minutes to form an electrodeposition coating film of 15 μm. Finally, baking and drying were performed at 180 ° C. for 30 minutes to obtain a glossy composite film having a gray bronze color.

The color was measured with the same colorimeter, and the following results were obtained. L ^* = 48.7, a ^* = 1.9 b ^* = 4.6

When this is compared with the case of the first embodiment, an electrodeposition paint containing 0.1% by weight of titanium white having a particle diameter of 5 μm in a bronze anodized film having an L ^* value of more than “27”. In the same electrolysis treatment for the same 2 minutes, and the same 15 minutes
Even when an electrodeposition coating film having a thickness of μm is formed, the color effect of the underlayer (bronze-colored anodic oxide film) is strong and the index a ^* tends to be red.
At 9 ", only a light gray-based bronze color can be obtained such that the index b ^* is" 4.6 "with a yellow tendency.

[0042]

According to the present invention, an anodic oxidation treatment is applied to an aluminum material or an aluminum alloy material to form an anodic oxide film, and then an electrolytic coloring treatment is performed to color the anodic oxide film black. Particle size 0.5 to 10 μm
And a composite coating for forming an electrolytic coating in an electrodeposition coating solution containing 0.01 to 0.5% by weight of a white pigment on the black anodic acid coating to form a white coating on which the black anodic oxide coating can be seen. Since it is a forming method, a composite film of a bluish gray color close to an achromatic color can be stably formed with high reproducibility. Therefore, it is possible to provide a bluish-gray building material, an exterior product, and the like which are excellent in corrosion resistance and weather resistance with a new color and rich in mass feeling and the like at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of forming a composite film according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum material 10 Anodized film (black anodized film) 11 Micropore 20 Precipitated metal (black anodized film) 30 White film 31 White pigment

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-57493 (JP, A) JP-A-3-183798 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C25D 11/20 304 C25D 11/22 301 C25D 11/22 306 C25D 11/22 310

Claims (1)

(57) [Claims] 1. An anodizing treatment is performed on an aluminum material or an aluminum alloy material to form an anodizing film, and then an electrolytic coloring treatment is performed to color the anodizing film black. 0.01 to 10 μm
An electrolytic treatment in an electrodeposition coating solution containing 0.5% by weight of a white pigment to form a white coating film on the black anodic acid coating film through which the black anodic oxide coating film can be seen. For forming a blue-gray composite film of aluminum and aluminum alloy.