JPS607038B2 - 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 steel alloy material to form a uniform colored layer with excellent adhesion on the surface.

Conventionally, copper products have the drawbacks of poor color appearance and discoloration due to oxidation, so they have been colored into 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 copper 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, if the copper product is a flat plate and the flat plate is installed parallel to the negative electrode of the electrolyte, the current will flow more easily in the green surrounding area, so the green surrounding area will be colored well and the entire surface of the plate will be uniformly colored. Furthermore, when the copper product to be colored is three-dimensional, there is a further disadvantage that there are areas that are not colored because the current density is even more different.

Furthermore, sulfur dioxide is dissolved in the electrolyte, sulfate,
Although it is known that the color tone and adhesion of the colored layer can be improved by adding sulfite or the like, even with this method it has not been possible to form a uniform colored layer.

The purpose 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 that is uniform, has excellent adhesion, and exhibits a naturally occurring green-blue color on copper or copper alloy materials by electrolytic anodizing treatment. The gist is that a copper or steel alloy material is treated with an alkali metal or ammonium carbonate, at least one of oxycarboxylic acid and divalent carboxylic acid, and sodium hydrosulfite or Copper is characterized by being subjected to electrolytic anodizing treatment by immersing it in an electrolytic solution containing sodium thiosulfate and an electrolytic solution containing a primary or secondary phosphate in a water bath. It consists in the method of coloring alloy materials.

In the present invention, the electrolytic solution contains an alkali metal or ammonium carbonate, at least one of oxycarboxylic acid and divalent carboxylic acid, and sodium hydrosulfite or sodium thiosulfate, and more preferably contains a water-soluble and the first or second phosphate salt.

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, baroxyacid, tartaric acid, glyconic 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.

Further, sodium hydrosulfite or sodium thiosulfate may be anhydrous or may contain water of crystallization. Furthermore, the phosphates include water-soluble primary or secondary phosphates, such as primary sodium phosphate, primary potassium phosphate, primary ammonium phosphate, secondary sodium phosphate, Secondary phosphates such as dibasic potassium phosphate and diammonium phosphate are preferably used. The content of carbonate, oxycarboxylic acid or divalent carboxylic acid, sodium hydrosulfite or sodium thiosulfite, and phosphate in the electrolytic solution is 0.2 to 0.8 mol/〆 for carbonate. , 1 to 30 T for oxycarboxylic acid or divalent carboxylic acid, 0.00 for sodium hydrosulfite or sodium thiosulfate
5-0.25 mol/〆, 0.15-0 for phosphates
．． Preferably it is 30 moles/range. 0 carbonates
．． When the current density is less than 2 mol/day, it becomes difficult to form a colored layer on the surface of copper due to electrolytic anodizing treatment even if the current density is adjusted, and when it is more than 0.8 mol/day, the color tone of the colored layer becomes black. You will not be able to color the product to a beautiful tone.

The most preferred range of carbonate is 0.4 to 0.6 mol/sole. For oxycarboxylic acids or divalent carboxylic acids, if it is less than 1 night, the effect of adding acid to the electrolytic solution, that is, eliminating uneven coloring and improving the adhesion of the colored layer, is not sufficient; This is because when the amount increases from evening, the colored layer gradually becomes thinner and finally stops producing color.

The most preferred range of such acids is from 5 to 20 degrees.
In addition, if the amount of sodium hydrosulfite or sodium thiosulfate is less than 0.005 mol/〆, the effect of adding these to the electrolyte, that is, eliminating uneven coloring and improving the adhesion of the colored layer, will not be sufficient; If the amount is more than 25 moles, the color tone will change and the color tone will be yellowish, so it is preferable, and the most preferable range of addition amount is 0.02 mole.
5 to 0.05 mol/sleeve.

Furthermore, in the present invention, water-soluble primary or secondary phosphates, such as primary sodium phosphate, primary potassium phosphate, primary potassium phosphate, etc., are added to the electrolyte.
When primary phosphates such as ammonium phosphate, secondary sodium phosphates, secondary potassium phosphates, secondary ammonium phosphates, etc. are added, the surface of the colored layer becomes even smoother, resulting in uniform coloring. In addition to this, the adhesion is further improved.

The amount of such phosphate added is 0.015 to 0.3 mol/s,
Preferably it is 0.05 to 0.08 mol/so. 0.0
If it is less than 15 mol/l, the effect of adding phosphate will not be sufficient, and if it is more than 0.3 mol/l, the color tone will gradually become lighter and no coloring will occur.

The above carbonate, oxycarboxylic acid or divalent carboxylic acid,
Sodium hydrosulfite or sodium thiosulfate and phosphate salts may be used alone or in combination of two or more.

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

The current density in electrolytic anodizing treatment is based on the carbonate contained in the electrolytic solution, oxycarboxylic acid or divalent carboxylic acid, sodium hydrosulfite or sodium thiosulfate,
Although it varies depending on the combination with phosphate and the content, 2. Above pine'd〆, electrolyte temperature is 20-4
It is preferable to set it to 0oo.

If the current density is less than 2.5 A/d force, even if the content of carbonates, etc. contained in the electrolyte is increased, it will be difficult to color the copper or steel alloy material. temperature is 200
If it is lower than 0, the color tone will be bad and the surface will not be smooth.
This is because when it becomes higher than 40oo, the color tone becomes black.

In addition, the time for electrolytic anodizing treatment varies depending on the surface area of the copper or steel alloy material to be treated, current density, distance between the treated material and the electrode, temperature of the electrolyte, etc. , the higher the liquid temperature, the shorter the processing time.
I'll try it.

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 equidistant from the cathode in order to achieve uniform coloring.

For this reason, depending on the shape of the treated material, it is possible to color multiple treated materials at once by suspending the treated material 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 pre-treated and well-degreased copper (or copper alloy) material is immersed in the electrolyte bath and subjected to the electrolytic anodization treatment as described above, a uniform colored layer will be formed over the entire surface.

Although this colored layer has sufficient adhesion, it may fall off when an impact force is applied, so to prevent this and improve durability, a protective coating is applied to the surface of the colored layer. It is best to form layers.

Conventionally known protective coating layers can be used.

For example, it can be formed by spraying an acrylic solution type paint, an acrylic urethane type two-component hardening type paint, and drying it by heating. Further, in the present invention, when electrolytic anodization treatment is performed, carbonates and the like contained in the electrolytic solution are consumed, so it is preferable to replenish the consumed amount to always keep the content in the electrolytic solution constant.

Further, since products such as copper oxide that have an adverse effect on the coloring process are generated in the electrolytic solution, it is preferable to remove these products by occasionally passing the electrolytic solution through a furnace.

Next, examples of the present invention and comparative examples will be shown. Example 1 An electrolytic solution containing 60 tons of sodium carbonate, 10 tons of tartaric acid, and 5 tons of sodium hydrosulfite was placed in a plastic container measuring 12 cm long, 7 mm wide, and 5 layers deep. The container is used as an electrolyte tank, and a steel plate is attached to one inner wall surface in the horizontal direction of the container to serve as a negative electrode.

A copper plate to be colored (a degreased copper plate of 10 x 5 x 0.3 mm thick) is placed facing the negative electrode steel plate at an angle of about 45 degrees, with one end measuring about 5 centimeters and the other end about 5 centimeters thick. Immerse it in the electrolyte tank so that it becomes 12c.

Then, the steel plate to be colored is connected to the anode and the negative electrode at an average current density of 3. The current at ship/d is 3
After running the water for several minutes, the surface facing the negative electrode had a blackish deep green-blue color with a mixture of green, blue, and yellow (a naturally occurring green-blue color), even though the distance from the negative electrode was different. A uniform colored layer was formed.

The temperature of the electrolyte was 2000℃.

After washing the colored steel plate with water and drying it, the adhesion of the colored layer was tested as follows.

The adhesion was determined by cutting vertically and horizontally at a pitch of 1 on a colored layer with an area of 1 square, creating ION solid grids, pressing cellophane tape on top of it with your fingertips, and peeling it off. Vertical tape peeling test, which is determined by the number of squares where the colored layer remains over 50% of the area, and immersion in running water (in a container that replaces 10 to 15 strips/ml of tap water). A test (1 week) was conducted. As a result, in the side-by-side tape peeling test, it was judged that there was no peeling in all of the loo times, and there was almost no peeling even partially in each side, 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 bond immersion test.

Examples 2 and 3 and Comparative Examples 1 to 3 In Example 1, the electrolyte solution and current density were changed as shown in Table 1, and in each comparative example, the energization treatment time was further changed to 10
The coloring process was carried out using the same machine as in Example 1 except that the coloring process was carried out for a minute.

The colored layers obtained in Examples 2 and 3 of Table 1 exhibited almost the same color tone as the natural green-blue color that was uniform over the entire surface as in Example 1, and the color tone of the colored layers obtained in Examples 2 and 3 was almost the same as that of Example 1. It was judged that there was no peeling in all cases, and there was almost no peeling even partially in each test.

Also, in the bond immersion test, there was no change in the colored layer at all. On the other hand, in each of the comparative examples, the side of the copper plate to be colored where the gap between the negative electrode copper plate and the negative electrode copper plate is narrow, that is, the side where current flows easily, is colored unevenly and in a mottled manner. 20% of the surface area of the steel plate facing the electrode steel plate (Comparative Example 1
), 5% (Comparative Examples 2 and 3).

In addition, the color tone was blue-white in Comparative Examples 1 and 2, but in Comparative Example 3, it was slightly blackish and blue, both of which were different from natural green-blue.

In addition, in a test for peeling off the colored layer using tape, it was determined that there was no peeling at all 10 hard stitches in each comparative example, but in Comparative Example 1, the colored layer was in a powder form. This is because the cellophane 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 3 was poured into a stainless steel plate tank with a width of 60 mm, a length of 3 mm, and a depth of 1 m, and a copper plate was applied along the length. The treated synthetic resin rain gutters and parts (elbows, water collectors, etc.) are submerged.
Electrolytic anodic oxidation treatment was carried out by connecting each rain gutter and its parts to the anode and the rice cake to the cathode, and flowing a current at a current density of 3.5 A/d for 3 minutes.

On the outer surface of each rain gutter and component, a colored layer with a uniform color tone almost the same as natural green-blue and with good adhesion was formed over the entire surface. As described above, the present invention provides an electrolytic solution containing an alkali metal or ammonium carbonate and at least one kind of sodium hydrosulfite or sodium thiosulfate among oxycarboxylic acid and divalent carboxylic acid, and this electrolytic solution. A coloring method in which a copper or copper alloy material is immersed in an electrolytic solution containing a water-soluble primary or secondary phosphate and electrolytically anodized, the method comprising: oxycarboxylic acid or divalent carboxylic acid; By adding sodium hydrosulfite or sodium thiosulfate, phosphates, etc., it is possible to form a colored layer on the surface of copper or steel alloys that is uniform, has excellent adhesion, and has a naturally occurring greenish-blue color.

Claims (1)

[Claims] 1. A copper or copper alloy material containing an alkali metal or ammonium carbonate, at least one of oxycarboxylic acid and divalent carboxylic acid, and sodium hydrosulfite or sodium thiosulfate. A method for coloring copper or copper alloy materials, which is characterized by immersing them in an electrolytic solution and electrolytically anodizing them. 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
30 g/l and the amount of sodium hydrosulfite or sodium thiosulfate is 0.005 to 0.25 mol/l. 3 Copper or copper alloy material is mixed with an alkali metal or ammonium carbonate, at least one of oxycarboxylic acid and divalent carboxylic acid, sodium hydrosulfite or sodium thiosulfate, and a water-soluble first or second A method for coloring copper or copper alloy materials, which comprises immersing them in an electrolytic solution containing a phosphate and subjecting them to electrolytic anodic oxidation treatment. 4 Carbonate contained in the electrolyte is 0.2 to 0.8 mol/
1, and the oxycarboxylic acid or divalent carboxylic acid is 1
-30 g/l, sodium hydrosulfite or sodium thiosulfate is 0.005-0.25 mol/l, and phosphate is 0.015-0.3 mol/l. Coloring method described in section.