JP3171995B2 - Electrolytic coloring of metal materials - 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 electrolytically coloring a metal material, which is mainly intended for stainless steel, but which can provide beautiful and various colors to other general metal materials.

[0002]

2. Description of the Related Art A general method for forming a color on a stainless steel surface is as follows.
A colored film is formed by a natural immersion method for about 0 to 1000 minutes. Metals capable of coloring are limited to the range of stainless steel, and application to other metals is extremely difficult. The color control of the present method is characterized in that it is identified by the difference in potential that changes during immersion. That is, the conventional method of forming a color at a high temperature of 80 to 90 ° C. using a high concentration of dichromate / sulfuric acid is called a parakeet method, and this method contains highly toxic hexavalent chromium, and
There is a problem in the working environment because high temperature and high concentration sulfuric acid is used. Further, depending on the color tone, it takes 10 hours or more, and the productivity is also poor. There is also a disadvantage that the same color tone cannot be obtained by the α-system and the γ-system in the metallographic structure of stainless steel.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a beautiful color forming method which can be applied to general metal materials other than stainless steel, can be operated safely, at low cost, at room temperature, and has few defects such as color unevenness. To offer.

[0004]

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

[0005]

Action and Embodiment The aqueous salt solution used in the present invention comprises:
It is a solution at a liquid temperature of 7 ° C. to 50 ° C. containing, as essential components, 0.3 to 5.0% of potassium permanganate and 0.3 to 3.0% of iron citrate or iron oxalate. In the solution, any one of the following electrolysis methods (1) to (3) is performed to form a color developing film made of insoluble colored hydroxide or oxide of manganese or iron on the surface of the metal material. Energizing method: DC method (cathode treatment after anodizing) DC method (cathode treatment) Alternating method (0.005 to 1.0 Hz) A silica sol solution is added to the treatment liquid in a range of 0.5 to 50%, and color formation comprising insoluble colored hydroxides or oxides of manganese, iron, and silica on the surface of a metal material such as stainless steel under the same treatment conditions as described above. It is possible to form a film. The addition of silica enhances the wear resistance and corrosion resistance of the coloring film.

Color tone control A color-forming film is formed on the surface of a metal material such as stainless steel in the above solution by a direct current method or an alternating method. In the direct current method, the color tone is controlled by adjusting the current density and the processing time. In, the color tone is controlled by adjusting the frequency, current density, and processing time. The color tone that can be developed is such that all colors are obtained except for pure white and pure red, and it is a transparent interference color. In the present invention, the reason for limiting the concentration of the aqueous salt solution is that potassium permanganate, iron citrate, etc.
If the amount is less than 5%, the coloring reaction is weak and the color development is insufficient, and if potassium permanganate exceeds 5.0% or iron citrate exceeds 3.0%, color unevenness occurs and the color tone becomes poor. Because it is inferior. If the addition amount of silica sol is less than 0.5%, the effect of improving the abrasion resistance and corrosion resistance of the coloring film is insufficient, and if it exceeds 50%, the liquid resistance becomes large and electrolysis becomes impossible. If the temperature of the treatment liquid is lower than 7 ° C., the color forming reaction is slow and a beautiful color tone cannot be obtained, and if the temperature exceeds 50 ° C., it is not preferable in terms of cost, safety and the like. The reason for limiting the energizing conditions is that if the current density is less than 0.01 A / dm ² or the processing time is less than 3 seconds, a color reaction cannot occur, and the current density exceeds 3.0 A / dm ² . Or processing time 900
If the time exceeds seconds, remarkable color unevenness occurs, and normal coloring cannot be obtained.

[0007]

The method of the present invention is superior to the known parakeet coloring method in the following points. Although the parakeet method targets stainless steel, this method can produce beautiful colors even on general metal materials other than stainless steel. The parakeet method contains highly toxic hexavalent chromium and uses high-temperature and high-concentration sulfuric acid. However, this method uses permanganate, iron citrate, iron oxalate, Silica sol is almost neutral, less toxic and safe. Each of the compounds contained as the composition of the color developing solution has a low concentration, so that costs can be saved. The current density at the time of electrolytic coloring is also 0.05 to 1.5 A / dm ^2.
And the running cost is relatively low. The processing solution temperature during electrolytic color development is, in principle, normal temperature, and normal color development is possible even if the temperature rises to about 50 ° C. due to reaction heat. The parakeet method is based on spontaneous color development, and if there is a non-uniform part such as welding on the surface of the color-receiving material, severe color unevenness occurs. Also, the color difference between the steel types is large. On the other hand, since the method of the present invention is controlled color development by electrolysis, a predetermined beautiful color can be obtained with almost no unevenness of color in a heterogeneous portion and color difference between materials.

[0008]

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

[0009]

Example 1 Steel type: SUS 304 Dimensions: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring conditions: Treatment solution composition: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.2 to 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 washing with a solvent (benzene, alcohol). Coloring conditions: Composition of treatment solution: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C. Counter electrode material: graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.5 A / dm ² constant Processing time: 10 to 40 seconds

[0011]

Example 3 Steel type: SUS 304 Dimension: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring conditions: composition of treatment solution: 2.0% potassium permanganate + 1.0% iron ammonium citrate + 50% silica sol Treatment solution temperature: 22 ° C Counter electrode material: graphite for electrolysis DC treatment: cathode treatment after anodization Current density: 0 0.2 to 0.8 A / dm ² treatment time: 30 seconds for both anode and cathode

[0012]

Example 4 Steel type: SUS430 Dimensions: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring conditions: Treatment solution composition: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C Counter electrode material: Graphite for electrolysis DC treatment: Cathode treatment after anodization Current density: 0.2 to 0.8 A / dm ² treatment time: 30 seconds constant for both anode and cathode

[0013]

Example 5 Steel type: SUS430 Dimensions: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring conditions: Treatment solution composition: 2.0% potassium permanganate + 1.0% iron ammonium oxalate Treatment solution temperature: 22 ° C Counter electrode material: Graphite for electrolysis Treatment method: Cathodic electrolytic treatment Current density: 0.2 to 0. 8A / dm ² treatment time: an anode, a cathode both 30 seconds constant

[0014]

Example 6 Steel Type: Steel Dimensions: 1.0 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring condition: Composition of treatment solution: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C Material of opposite electrode: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1 Hz) Current density: 0 .2~0.8A / dm ² treatment time: an anode, a cathode both 10 seconds constant

[0015]

Example 7 Steel type: Mild steel Dimension: 0.5 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring condition: Composition of treatment solution: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C Material of opposite electrode: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1 Hz) Current density: 0 .2~0.8A / dm ² treatment time: an anode, a cathode both 10 seconds constant

[0016]

Example 8 Steel type: Tin plate Dimensions: 0.5 ^t × 50 × 150 mm Pretreatment: Degreasing and washing with a solvent (benzene, alcohol). Coloring condition: Composition of treatment solution: 2.0% potassium permanganate + 1.0% iron ammonium citrate Treatment solution temperature: 22 ° C Material of opposite electrode: Graphite for electrolysis Treatment method: Alternating electrolysis method (0.1 Hz) Current density: 0 .2~0.8A / dm ² treatment time: an anode, a cathode both 10 seconds constant

Claims (5)

(57) [Claims] 1. A potassium permanganate 0.3-5.0%
And iron citrate or iron oxalate 0.3 to 3.0%
An electrolytic coloring method for a metal material, comprising subjecting the metal material to an electrolytic treatment by a direct current method or an alternating method in an aqueous salt solution at 7 ° C to 50 ° C. 2. An aqueous salt solution comprising 0.5 to 50 silica sol.
2. The method according to claim 1, comprising%. 3. The method according to claim 1, wherein the direct current electrolysis treatment has a current density of 0.01 to 0.01.
3.0A / dm ^2, treatment is anodised after cathodic treatment time 3-900 seconds The process according to claim 1 or 2. 4. The method according to claim 1, wherein the direct current electrolysis treatment has a current density of 0.01 to 0.01.
3.0A / dm ^2, a cathodic treatment in processing time 3-900 seconds The process according to claim 1 or 2. 5. The method according to claim 1, wherein the alternating electrolytic treatment is carried out at a current density of 0.01 to 0.01.
3.0A / dm ^2, alternating electrolysis treatment time 3-900 seconds which is (0.005~1.0HZ) The process according to claim 1 or 2.