JPS6034640B2 - 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.

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, a chemical method of repeatedly applying a chemical solution containing copper salts and acids is used to color greenish-blue colors, but the application and drying must be repeated over and over again, and the coloring process is time-consuming and labor-intensive. 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, if the copper product is a flat plate and the flat plate is installed parallel to the negative electrode used in electrolysis, the current will flow more easily around the peripheral wire, 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 provide a coloring method that forms a colored layer with uniform color tone and excellent adhesion on copper or steel alloy materials by electrolytic anodizing treatment 10-6. The gist is that copper or steel alloy material is treated with an alkali metal or ammonium carbonate and at least one of water-soluble primary and secondary phosphates.
A method for coloring a copper or copper alloy material, characterized by immersing the material in an electrolytic solution containing seeds and subjecting it to electrolytic anodic oxidation treatment.

In the present invention, the electrolytic solution contains an alkali metal or ammonium carbonate and at least one of water-soluble first and second phosphates.

As carbonates, sodium carbonate, potassium carbonate, ammonium carbonate, etc. are preferably used, and as phosphates, water-soluble primary or secondary phosphates, such as primary sodium phosphate,
Primary phosphates such as potassium primary phosphate and ammonium primary phosphate;
Secondary phosphates such as secondary sodium phosphate, secondary potassium phosphate, and secondary ammonium phosphate are preferably used.

The content of carbonates and phosphates in the electrolyte is 0.2 to 0.8 molnoc for carbonates and 0.01 molnoc for phosphates.
It is preferably in the range of 5 to 0.3 mol/mol.

If the carbonate content is less than 0.2 mol/mol, a colored layer will be formed on the surface of the copper due to electrolytic anodization treatment even if the current density is adjusted, and if the carbonate content is more than 0.8 mol/l, the colored layer will be formed. The color tone becomes black and it becomes impossible to color the product in a fruitful tone. The most preferred range of carbonate is 0.4 to 0.6 mol/sole. In addition, if the phosphate is less than 0.015 mol/〆, the effect of adding phosphate to the electrolyte, that is, the elimination of uneven coloring and the improvement of the adhesion of the colored layer, will not be sufficient; This is because if the amount is higher than in the evening, the color will not develop.

The most preferred range of phosphate is about half of the carbonate content, which is 0.05 to 0.08 mol/s.

Regarding phosphates, for example, monobasic sodium phosphate is N
aH2P04・2L○, dibasic sodium phosphate is Na2
It may also contain water of crystallization, such as HP04/12th 20. Further, carbonates and phosphates may be used alone or in combination of two or more.

Furthermore, by adding a relatively inexpensive tertiary phosphate, the effects of the present invention will not be reduced even if the contents of relatively expensive primary and secondary phosphates are reduced. Economical.

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 varies depending on the combination and content of carbonate and phosphate contained in the electrolyte, but in various electrolytes, 2. It is preferable that the temperature of the electrolytic solution is 20 to 40q0.

Current density is 2. This is because if the carbonate and phosphate contents are lower than 20%, it will be difficult for copper to color the steel alloy material, and if the electrolyte temperature is lower than 20 oo, the color tone will change. This is because the surface is not smooth and the color tone becomes black when the number is higher than 40. 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 shorter the time and the higher the liquid temperature, the shorter the processing time will be.

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, if the treated material is hung in the center of a long and narrow electrolytic tank and cathode electrodes are installed along both sides of the electrolyte tank, a plurality of treated materials can be colored at the same time. The electrolyte bath itself may be used as a cathode.

If a pre-treated copper or steel 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 impact force is applied, so in order to prevent this and improve durability, a protective coating is added to the surface of the colored layer. It is better to form

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

For example, spraying acrylic solution type paint, acrylic urethane type two-component curing type paint, etc.
It can be formed by heating and drying. In addition, in the present invention, when electrolytic anodization treatment is performed, carbonates, phosphates, etc. in the electrolyte are consumed, so it is recommended to replenish the consumed amount to keep the content in the electrolyte constant. good.

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 50 m/m of sodium carbonate and 52 m/m of sodium phosphate was placed in a plastic container measuring 12 cm vertically, 7 arcs horizontally, and 5 cm deep. As a tank,
A steel plate is attached to one inner wall surface in the horizontal direction of the container to serve as a member electrode.

The steel plate to be colored (10c × 5 skin, 0.3 thickness degreased steel plate) faces the negative electrode steel plate at an angle of about 45 degrees, with one end about 5 skin and the other end about 5 skin. The copper plate to be colored is immersed in an electrolytic solution so as to have a diameter of 12 mm, and the copper plate to be colored is connected to the anode, and a current density of 6.0 A/d is applied between the plate and the negative electrode.
When a similar current was passed for 7 minutes, a uniform bluish-white colored layer was formed on the surface facing the negative electrode, even though the distance from the negative electrode was different. , the temperature of the electrolyte was 20 oo.

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

The adhesion was 50% when the colored layer with an area of 1 square was made vertically and horizontally with cuts of 1 willow pitch to create ION-hard grids, and cellophane tape was pasted on top of it by pressing it with your fingertips and peeled off. % or more of the area where the colored layer remains, a test for peeling off the side tape, and a test for soaking in running water (in a container where the tap water is replaced between 10 and 15 minutes). 1 week). As a 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 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 immersion test.

Examples 2 to 7 and Comparative Examples 1 to 3 The same as Example 1, except that the electrolyte and current density were changed as shown in Table 1, and in each Comparative Example, the energization treatment time was changed to overnight. Coloring treatment was carried out in the same manner as in 1.

The colored layers obtained in Examples 2 to 5 in Table 1 exhibited a uniform bluish-white color over the entire surface as in Example 1, and in the side-by-side tape peeling test, it was determined that there was no peeling at all the sides of Ion hard. There was almost no partial peeling of each grain, and there was no change in the colored layer at all in the bond test.

On the other hand, in each of the comparative examples, the side of the copper plate to be colored where the distance between the negative electrode steel plate and the negative electrode steel plate is narrow, that is, the side where current flows easily, is colored unevenly and in a mottled manner, and the proportion of the colored area is smaller than that of the negative electrode steel plate. They were 20% (Comparative Example 1) and 5% (Comparative Examples 2 and 3) of the surface area of the steel plate facing the steel plate. 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 the colored layer side-by-side tape peeling test, it was determined that there was no peeling in all the ION solid lines 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 squares.

Furthermore, when an immersion test in running water was conducted, the colored layer 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 6 The same electrolyte as used in Example 1 was poured into a stainless steel plate 60cm wide, 3cm long, and 1m deep to form an electrolyte tank, and copper plated along the length. The treated 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 3.0 A/d was passed for 7 minutes to perform electrolytic anodization.

A bluish-white colored layer with uniform color tone and good adhesion was formed on the outer surface of each rain gutter and component. As described above, the present invention involves immersing a steel or copper alloy material in an electrolytic solution containing an alkali metal or ammonium carbonate and at least one of water-soluble primary and secondary phosphates. A coloring method that involves crushing and electrolytic anodizing treatment,
By adding a phosphate salt, a colored layer that is uniform and has excellent adhesion can be formed on the surface of copper or copper alloy.

In addition, even if the copper or copper alloy material to be colored has a three-dimensional shape, a uniform colored layer can be formed on the entire outer surface. This method is useful as an industrial coloring method for coloring building materials such as copper-plated synthetic resin rain gutters and their parts, coloring decorative copper products, and coloring arts and crafts.

Claims (1)

[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 water-soluble primary and secondary phosphates, and electrolyzed. A method for coloring copper or copper alloy materials, which is characterized by anodizing. 2 The carbonate contained in the electrolyte is 0.2 to 0.8 mol/
1. The coloring method according to claim 1, wherein the phosphate is 0.015 to 0.3 mol/l.