JPS607036B2 - How to color copper or copper alloy materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of electrolytically anodizing a copper or copper alloy material to form a uniform colored layer with excellent adhesion on the surface.

However, copper products have the disadvantage of having poor color appearance and being easily discolored by oxidation, so they are colored in various tones by chemical methods, electrochemical methods, etc.

For example, there is a chemical method of repeatedly applying a chemical solution containing a copper salt and an acid to color it greenish-blue; This was not a preferred method for industrially coloring products. There is also an electrochemical method in which the steel product to be colored is used as an anode for electrolytic oxidation treatment in an electrolytic solution containing sodium carbonate or sodium bicarbonate, but the adhesion of the colored layer is poor and the current density is not uniform. There was a drawback that a uniform colored layer could not be obtained.

For example, when a copper product is a flat plate, even if the flat plate is installed parallel to the negative electrode used in electrolysis, the current flows more easily at the periphery, so the cylindrical part is colored well and the entire surface of the plate is not uniformly colored. Moreover, when the copper product to be colored is three-dimensional, there is a further disadvantage that there is a difference in current density, resulting in uncolored parts. Furthermore, it is known that the color tone and adhesion of the colored layer can be improved by dissolving sulfur dioxide or adding sulfate, sulfite, etc. to the electrolytic solution, but even with this method, it is still difficult to form a uniform colored layer. could not be formed.

An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional methods and to provide a coloring method that forms a colored layer with uniform color tone and excellent adhesion on copper or copper alloy materials by electrolytic anodizing treatment. , the gist of which is that a copper or steel alloy material is treated with an alkali metal or ammonium carbonate and at least one of an oxycarboxylic acid and a divalent carboxylic acid.
A method for coloring a copper or copper alloy material is characterized by immersing the material in an electrolytic solution containing seeds and subjecting it to electrolytic anodizing treatment.

In the present invention, the electrolytic solution contains an alkali metal or ammonium carbonate and an oxycarboxylic acid or a divalent carboxylic acid.

As the carbonate, sodium carbonate, potassium carbonate, ammonium carbonate, etc. are preferably used.

In addition, suitable oxycarboxylic acids include glycolic acid, lactic acid, malic acid, citric acid, Q-oxyacid, tartaric acid, gluconic acid, and 8-oxypropionic acid, and examples of divalent carboxylic acids include oxalic acid and succinic acid. Suitable acids include itaconic acid, citraconic acid, mesaconic acid, oxalacetic acid, acetylene dicarboxylic acid, maleic acid, fumaric acid, and the like.

The content of carbonate and oxycarboxylic acid or divalent carboxylic acid in the electrolytic solution is 0.2 to 0.8 mole for carbonate and 1 to 30 mole for oxycarboxylic acid or divalent carboxylic acid. evening/preferably in that range.

When the amount of carbonate is less than 0.2 mol, it becomes difficult to form a colored layer on the surface of copper by electrolytic anodizing treatment even if the current density is adjusted, and when the amount is more than 0.8 mol, the color tone of the colored layer decreases. becomes black and cannot be colored in a beautiful tone.

The most preferred range of carbonate is 0.4-0.

6 mol/sleeve.

For oxycarboxylic acid or divalent carboxylic acid, 1
If it is less than 309/3, the effect of adding acid to the electrolyte, that is, eliminating uneven coloring and improving the adhesion of the colored layer, will not be sufficient, and if it is more than 309/30, the colored layer will gradually become thinner, and finally the color will develop. This is because they will no longer do so.

The most preferred range of such acids is from 5 to 20 degrees.
In the present invention, the above-mentioned carbonate and oxycarboxylic acid or divalent carboxylic acid may be used alone or in combination of two or more.

In the present invention, the electrolytic solution contains a water-soluble first or second phosphate, for example, a first or second phosphate such as sodium first phosphate, potassium first phosphate, ammonium first phosphate, etc. sodium,
When phosphates such as dibasic potassium phosphate and diammonium phosphate are added, the surface of the coloring agent becomes smoother, uniform coloring can be achieved, and adhesion is further improved.

The amount of the phosphate added is 0.015 to 03 mol/s, preferably 0.05 to 0.08 mol/s, and 0.01 to 0.03 mol/s.
This is because if it is less than 5 mol/day, the effect of adding the phosphate will not be sufficient, and if it is more than 0.3 mol/day, the color tone will gradually become lighter and no coloring will occur.

In the present invention, a copper or steel alloy material is immersed in the electrolytic solution, and the copper or steel alloy material is electrolytically anodized using the copper alloy material as an anode.

The current density in electrolytic anodizing treatment varies depending on the combination and content of carbonate and oxycarboxylic acid or divalent carboxylic acid contained in the electrolytic solution, but in various electrolytic solutions, 2. More than my power, the temperature of the lightning solution is 20-4000
It is preferable that

If the current density is less than 2.5 A/d, even if the content of carbonate, oxycarboxylic acid, or divalent carboxylic acid is increased, it will be difficult to color the copper alloy material. ,
Further, if the electrolyte temperature is lower than 20 CO, the color tone will be bad and the surface will not be smooth, and if it is higher than 4000 CO, the color tone will become black. In addition, the time for electrolytic anodizing treatment varies depending on the surface area of the steel alloy material, current density, distance between the treated material and the electrode, temperature of the electrolyte, etc. The shorter the distance and the higher the liquid temperature, the shorter the processing time.

The color tone of the colored layer is determined by the type and amount of acid added in the electrolyte.
It varies depending on the processing time, etc., and if the amount added is large and the processing time is long, the color tone will be dark.

It is preferable to arrange the treatment material and the electrode in the electrolyte bath so that the treatment material used as an anode is approximately equidistant from the cathode in order to achieve uniform coloring.

0 For this reason, depending on the shape of the treated materials, it is possible to color multiple treated materials at once by suspending the treated materials in the center of a long and narrow electrolyte tank and installing cathode electrodes along both sides of the electrolyte tank. The electrolyte bath itself may be used as a cathode.

If a pretreated copper or copper alloy material whose surface has been well degreased is immersed in the electrolytic solution bath described above and electrolytically anodized as described above, a uniform colored layer will be formed over the entire surface.

Although this colored layer has sufficient adhesion, it may peel off when a force is applied to it, so in order to prevent this and improve durability, the surface layer of the colored layer is It is preferable to form a protective coating layer on the surface.

As the protective coating layer, conventionally known ones can be used.

For example, spraying acrylic solution type paint, acrylic urethane type two-component hardening type paint, etc.
It can be formed by heating and drying. In addition, in the present invention, carbonates, oxycarbosic acids, divalent carboxylic acids, phosphates, etc. in the electrolytic solution are consumed during the electrolytic anodizing treatment, so the consumed amount is replenished and the electrolytic solution is constantly maintained. It is better to keep the content constant.

In addition, since products that adversely affect the coloring of oxidized steel and the like are produced in the electrolyte, it is recommended that the electrolyte be filtered from time to time to remove these products.

Next, examples of the present invention and comparative examples will be shown. Example 1 An electrolytic solution containing 609 parts of sodium carbonate and 10 parts of tartaric acid is put into a plastic container measuring 12 cm in length, 7 parts in width, and 5 parts in depth to form an electrolytic solution tank.

A steel plate is attached to one inner wall surface in the horizontal direction of the container to serve as a negative electrode. The steel plate to be colored (10 skins x 5 skins, 0.3 thickness degreased copper plate) faces the negative electrode steel plate at an angle of about 45 degrees, with one end about 5 degrees and the pond edge about 12 degrees. Pour into the electrolyte tank in the form of an arc.

Then, the steel plate to be colored was connected to the anode, and a current with a current density of 8 A'd was passed through the sand between the negative electrode and the surface facing the negative electrode. Despite the difference in spacing, a uniform blue colored layer was formed over the entire surface.

The temperature of the electrolyte was 2000℃.

After washing and drying the colored copper plate, the adhesion of the colored layer was tested as follows.

Adhesion: When a colored layer with an area of 1 square meter is made vertically and horizontally with cuts of 1 side pitch to create ION-hard grids, cellophane tape is pressed on top of it with fingertips, attached and peeled off. A side-by-side tape peeling test, which is determined by the number of squares in which the colored layer remains over 50% of the area, and immersion in running water (in a container that replaces 10 to 15 square meters of tap water). We conducted a bond test (1 week). "the result,
In the side-by-side/tape peeling test, it was determined that there was no peeling in all 100 times, and there was almost no peeling even partially in each place, and there was also no peeling on the side near the negative electrode. There was no difference in adhesion between the colored layer and the far side, and there was no change in the colored layer in the bonding test.

Examples 2 to 3 and Comparative Examples 1 to 3 Same as Example 1 except that the electrolyte and current density in Example 1 were changed as shown in Table 1, and in each comparative example, the energization treatment time was further changed to 10 minutes. Coloring treatment was carried out in the same manner.

Although the colored layers obtained in Examples 2 to 3 of Table 1 were colored uniformly over the entire surface as in Example 1, although the color tones were different, all 100 squares were uniformly colored in the square tape peel test. It was determined that there was no peeling, and there was hardly any partial peeling among each batch, and there was no change in the colored layer at all in the forgery test.

On the other hand, in each of the comparative examples, the side of the steel plate to be colored where the distance from the negative electrode copper plate is narrow, that is, the side where the mist flow easily flows, is colored unevenly in a mottled manner, and the proportion of the colored portion is The surface area of the copper plate facing the member electrode steel plate was 20% (Comparative Example 1) and 5% (Comparative Examples 2 and 3).

The color tone was blue-white in Comparative Examples 1 and 2, but the color tone was slightly blackish and blue in Comparative Example 3.

In addition, in a test for peeling off the colored layer using tape, it was determined that there was no peeling in all of the ION hard stitches in each comparative example, but in Comparative Example 1, the colored layer was in powder form, and cellophane was not peeled off. This is because the tape did not adhere and the powder on the surface layer stuck and peeled off. In Comparative Examples 2 and 3, partial peeling of the colored layer occurred in more than half of the stitches.

Furthermore, when a bond test was conducted under running water, the colored layer was partially peeled off due to the flowing water.

Although a protective coating layer was applied on the colored layer in each comparative example, peeling of the colored layer could not be prevented.

Example 4 The same electrolyte as used in Example 2 was poured into a stainless steel plate tank with a width of 60 arcs, a length of 3 arcs, and a depth of lm, and a copper plate was applied along the length. The constructed synthetic resin rain gutters and parts (elbows, water collectors, etc.) are submerged.
Each rain gutter and parts were connected to the anode and the tank to the cathode, and a current with a current density of 8 A/d was passed through the inkstone sand for 3 minutes to perform electrolytic anodization.

A uniform green-blue colored layer with good adhesion was formed on the outer surface of each rain gutter and component.

As described above, the present invention involves soaking a copper or copper alloy material in an electrolytic solution containing an alkali metal or ammonium carbonate and at least one of an oxycarboxylic acid and a divalent carboxylic acid, A coloring method using electrolytic anodization treatment, in which at least one of oxycarboxylic acid and divalent carboxylic acid is added to achieve uniform and close contact with the surface of copper or copper alloy, and the type of acid is selected. By this, colored layers of various tones can be formed.

Claims (1)

[Scope of Claims] 1. A copper or copper alloy material is immersed in an electrolytic solution containing an alkali metal or ammonium carbonate and at least one of oxycarboxylic acid and divalent carboxylic acid to form an electrolytic anode. A method for coloring copper or copper alloy materials, which is characterized by oxidation treatment. 2 The carbonate contained in the electrolyte is 0.2 to 0.8 mol/
1, and the oxycarboxylic acid or divalent carboxylic acid is 1
The coloring method according to claim 1, wherein the amount is 30 g/l.