JPH06322591A - Electrolytic coloring method for metallic materials - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a beautiful coloring method for metal materials which can be applied to general metal materials other than stainless steel, which is safe, low cost, can be operated at room temperature, and has few defects such as color unevenness. [Structure] In a salt aqueous solution containing potassium permanganate 0.3 to 5.0% and iron citrate or iron oxalate 0.3 to 3.0% and having a liquid temperature of 7 to 50 ° C., The metal material is electrolyzed by the direct current method or the alternating method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to stainless steel, but also relates to an electrolytic coloring method for metallic materials, which can obtain beautiful and various colors for general metallic materials other than the above.

[0002]

2. Description of the Related Art A general coloring method on the surface of stainless steel is 1 in a high temperature solution containing a high concentration of dichromate and sulfuric acid.
A colored film is formed by a natural dipping method for about 0 to 1000 minutes. The color-forming metal is limited to the range of stainless steel, and its application to other metals is extremely difficult. The color tone control of this method is characterized by distinguishing by the difference of the electric potential that changes during immersion. That is, the conventional method of developing a color at a high temperature of 80 to 90 ° C. using a high concentration of dichromate / sulfuric acid is called the inco method, and this method contains highly toxic hexavalent chromium, and
Since high temperature and high concentration sulfuric acid is used, there is a problem in the working environment. Further, depending on the color tone, it takes ten or more hours to develop the color, and the productivity is poor. There is also a drawback in that the same color tone cannot be obtained due to the α-γ system in terms of the metallic structure of stainless steel.

[0003]

The object of the present invention is to provide a beautiful coloring method which can be applied to general metallic materials other than stainless steel, is safe, can be manufactured at low cost, and can be operated at room temperature, and has few defects such as color unevenness. To provide.

[0004]

That is, the gist of the present invention is as follows. Potassium permanganate 0.3
~ 5.0% with iron citrate or iron oxalate 0.3 ~
An electrolytic coloring method for a metal material, which comprises subjecting the metal material to an electrolytic treatment by a direct current method or an alternating method in a salt aqueous solution of 7% to 50 ° C containing 3.0%.

[0005]

ACTION AND EMBODIMENT The aqueous salt solution used in the present invention is
A solution having a liquid temperature of 7 ° C to 50 ° C containing 0.3 to 5.0% potassium permanganate and 0.3 to 3.0% iron citrate or iron oxalate as essential components. In the solution, any one of the following electrolysis methods is performed to form a color-forming film made of insoluble colored hydroxide or oxide of manganese or iron on the surface of the metal material. Energization method: DC method (anodic treatment followed by cathodic treatment) DC method (cathodic treatment) Alternate method (0.005-1.0 Hz) A silica sol solution is added to the treatment liquid in a range of 0.5 to 50%, and under the same treatment conditions as described above, a coloring formed of an insoluble colored hydroxide or oxide of manganese, iron or silica on the surface of a metal material such as stainless steel. It is possible to form a film. The addition of silica enhances the wear resistance and corrosion resistance of the color development film.

Color tone control In the above-mentioned solution, a coloring film is formed on the surface of a metallic material such as stainless steel by the direct current method or the alternating method. The color tone is controlled by the direct current method by adjusting the current density and treatment time. Then, the color tone is controlled by adjusting the frequency, current density, and processing time. The color tones that can be developed are all interference colors with a sense of transparency, with all colors except pure white and bright red being obtained. In the present invention, the reason for limiting the concentration of the aqueous salt solution is that potassium permanganate and iron citrate are 0.3
If it is less than%, the color reaction is weak and the color development is insufficient. If the content of potassium permanganate exceeds 5.0% or the content of iron citrate exceeds 3.0%, color unevenness occurs and the color tone becomes poor. Because it is inferior. If the amount of silica sol added is less than 0.5%, the effect of improving the abrasion resistance and corrosion resistance of the color-developing film is insufficient, and if it exceeds 50%, the liquid resistance increases and electrolysis becomes impossible. If the temperature of the treatment liquid is lower than 7 ° C, the color reaction is slow and a beautiful color tone cannot be obtained, and if it exceeds 50 ° C, it is not preferable in terms of cost and safety. The reason for limiting the energization conditions is that if the current density is less than 0.01 A / dm ² or the treatment time is less than 3 seconds, the color reaction cannot occur, and the current density exceeds 3.0 A / dm ² . , Or processing time is 900
If it exceeds the second, remarkable color unevenness occurs and normal coloring cannot be obtained.

[0007]

The method of the present invention is a coloring method which is superior to the known inco-type coloring method in the following points (1) to (3). The Inco method targets stainless steel, but this method can also produce beautiful colors on general metal materials other than stainless steel. The inco method uses hexavalent chromium, which is highly toxic, and uses sulfuric acid at high temperature and high concentration, but this method uses permanganate, iron citrate, iron oxalate, Silica sol is almost neutral, less toxic and safe. All the compounds contained in the composition of the color-developing solution have a low concentration, and the cost can be saved. The current density at the time of electrolytic coloring is also 0.05 to 1.5 A / dm ^2.
With a relatively low current, running costs are low. In principle, the temperature of the treatment liquid during electrolytic color development is room temperature, and normal color development is possible even when the temperature rises to about 50 ° C. due to the heat of reaction. Since the Inco method is based on natural color development, if there is a non-uniform portion such as welding on the surface of the material to be color-developed, severe color unevenness occurs. In addition, the color difference between steel types is also large. On the other hand, since the method of the present invention is controlled color development by electrolysis, there is almost no unevenness of color in the non-homogeneous portion and color difference between materials, and a predetermined beautiful color can be obtained.

[0008]

The present invention will be described in more detail with reference to the following examples.

[0009]

[Example 1] Steel type: SUS 304 Dimension: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and cleaning with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.2- 0.8 A / dm ² treatment time: 30 seconds constant for both anode and cathode

[0010]

[Example 2] Steel type: SUS 304 Dimension: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and cleaning with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.5A / dm ² constant processing time: 10-40 seconds

[0011]

Example 3 Steel type: SUS 304 Dimension: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Iron ammonium citrate + 50% Silica sol Treatment liquid temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Anode treatment followed by cathode treatment Current density: 0 ^{2 to} 0.8 A / dm ² treatment time: 30 seconds constant for both anode and cathode

[0012]

[Example 4] Steel type: SUS 430 Dimensions: 1.0 ^t x 50 x 150 mm Pretreatment: Degreasing and cleaning with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.2- 0.8 A / dm ² treatment time: 30 seconds constant for both anode and cathode

[0013]

[Example 5] Steel type: SUS 430 Dimensions: 1.0 ^t x 50 x 150 mm Pretreatment: Degreasing and washing with a solvent (benzine, alcohol). Coloring condition: treatment liquid composition: 2.0% potassium permanganate + 1.0% ammonium ammonium oxalate treatment liquid temperature: 22 ° C counter electrode material: graphite for electrolysis treatment method: cathodic electrolysis treatment current density: 0.2-0. 8 A / dm ² treatment time: 30 seconds constant for both anode and cathode

[0014]

[Example 6] Steel type: Steel material Dimensions: 1.0 ^t x 50 x 150 mm Pretreatment: Degreasing and cleaning with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ℃ Counter electrode material: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1Hz) Current density: 0 ^{2 to} 0.8 A / dm ² treatment time: 10 seconds constant for both anode and cathode

[0015]

[Example 7] Steel type: Mild steel Dimensions: 0.5 ^t x 50 x 150 mm Pretreatment: Degreasing and cleaning with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ℃ Counter electrode material: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1Hz) Current density: 0 ^{2 to} 0.8 A / dm ² treatment time: 10 seconds constant for both anode and cathode

[0016]

[Example 8] Steel type: Tin plate Dimensions: 0.5 ^t x 50 x 150 mm Pretreatment: Degreasing and washing with a solvent (benzine, alcohol). Coloring condition: Treatment liquid composition: 2.0% Potassium permanganate + 1.0% Ammonium iron citrate Treatment liquid temperature: 22 ℃ Counter electrode material: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1Hz) Current density: 0 ^{2 to} 0.8 A / dm ² treatment time: 10 seconds constant for both anode and cathode

Claims (5)

[Claims] 1. Potassium permanganate 0.3-5.0%
And iron citrate or iron oxalate 0.3-3.0%
An electrolytic coloring method for a metal material, which comprises electrolytically treating the metal material by a direct current method or an alternating method in a salt aqueous solution at 7 ° C. to 50 ° C. 2. A salt aqueous solution is silica sol 0.5 to 50.
The method of claim 1 including%. 3. The direct current method electrolysis treatment uses a current density of 0.01 to
The method according to claim 1 or 2, which is a cathodic treatment after anodizing at 3.0 A / dm ² and a treating time of 3 to 900 seconds. 4. The direct current method electrolysis treatment uses a current density of 0.01 to
The method according to claim 1 or 2, wherein the cathodic treatment is performed at 3.0 A / dm ² and a treatment time of 3 to 900 seconds. 5. The alternating electrolysis treatment is performed with a current density of 0.01 to
The method according to claim 1 or 2, which is an alternating electrolysis method (0.005-1.0HZ) with a treatment time of 3.0-A / dm ² and a treatment time of 3-900 seconds.