JPS5940222B2 - Manufacturing method for copper or copper alloy products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing copper or copper alloy products, and particularly to a method for manufacturing products that do not lose their luster or change color even after being left for a long period of time.

Copper or copper alloys can be made into pipes, plates, etc. by extrusion or rolling.
After being formed into other predetermined shapes, it is subjected to a reducing atmosphere annealing treatment for the purpose of removing distortion and imparting surface gloss.

The product obtained through this annealing process usually has a thickness of about 20°C.
It has an oxide film of 40°A and has a bright color appearance. However, when it is left in the atmosphere, it loses its luster and
Discoloration may occur and the product value may be significantly impaired.
This problem is particularly severe in the hot and humid summer months. Conventionally, as a measure to prevent this discoloration, a method of treating the surface of the product with a benzotriazole (C6H5N3) solution or a method of packaging with volatile rust-proof paper have been widely used. The former uses benzotriazole copper [(C6H4N
3) Forms a film of 2 CU]. Although this method can provide a certain degree of discoloration prevention effect, it takes a long time to dry after coating, and uneven drying can cause stains and cloudiness on the product surface. There are other problems, such as the fact that benzotriazole is unsuitable for treatment of benzotriazole, and the off-odor of benzotriazole harms the working environment. On the other hand, in the latter method, after the annealing treatment, the product is wrapped in rust-proof paper coated with a volatile rust preventive agent such as benzotriazole, and then the benzotriazole is applied to the product using benzotriazole, which evaporates. However, in order to obtain sufficient anti-discoloration effects, the packaging must be kept completely sealed, which is a technical problem. When the product has an internal cavity, it is difficult to form a uniform and sufficient coating over the entire surface of the product. The present invention was developed in view of the above circumstances, and prior to annealing in a reducing atmosphere, a coating film is applied to the surface of the product using a solution containing a certain amount of semi-drying oil or non-drying oil in a chlorinated organic solvent. A method for manufacturing a copper or copper alloy product in which an oxide film with excellent discoloration prevention effect is formed on the product surface by forming the coating film, drying the coating film to remove the solvent, and then annealing in a reducing atmosphere. This is what we provide.

The method of the present invention will be explained in detail below. According to the present invention, copper or copper alloy products (hereinafter abbreviated as "copper products") that are formed into pipes, plates, strips, or other predetermined shapes through normal processing processes such as extrusion and rolling are Prior to the reducing atmosphere annealing treatment, a coating film is applied to the surface using a solution (hereinafter referred to as "coating solution") prepared by diluting semi-drying oil or non-drying oil with a chlorinated organic solvent. As a semi-drying oil,
Examples include rapeseed oil, sesame oil, cottonseed oil, soybean oil, and rapeseed oil is particularly preferred.

Examples of non-drying oils include castor oil, camellia oil, and olive oil, with castor oil being particularly preferred. It should be noted that drying oils such as linseed oil are difficult to obtain reliable discoloration prevention effects, as shown in the examples below, and are not necessarily suitable as coating film components. As the chlorinated organic solvent, trichlorethylene (CCj2CHCl), perchlorethylene (C2Cl4), etc. can be used, and trichlorethylene is particularly suitable.

Although it is not impossible to use organic solvents other than chlorine, the use of solvents with hydroxyl groups (-0H), such as alcohols, should be avoided because the tendency for discoloration will increase. For the same reason, the organic solvent used in the present invention is required to be water-free. The concentration of the solute in the coating solution prepared by dissolving the semi-drying oil or non-drying oil as a solute in the above solvent is approximately 0.2% (by volume, The same applies hereafter). In particular, as shown in Examples below, it is desirable that the content be about 0.5% or more. Although there is essentially no need to specify an upper limit for the concentration, increasing the concentration too much will not significantly change the effect and will only increase the cost burden, so in practice, the upper limit is set at about 10.0%. is appropriate. The amount of the coating liquid applied to the product surface may be about 0.0159/Trl or more, and about 1.0
There is no need to exceed 9/Rrl.

The coating method may be any suitable method such as dipping, spraying or brushing. For example, when using the dipping method, a coating film of an appropriate thickness is formed by immersing the product in the coating solution for about 3 minutes. After forming a coating film, it is dried to remove the solvent in the coating film.

If chlorine ions (Cl-) remain in the coating film, the oxide film formed afterwards will turn black, so it is necessary to remove them sufficiently. The solvent may be removed by applying cold air or hot air at a temperature of about 50° C., or by leaving it in the air. After finishing drying, annealing treatment is performed in an annealing furnace.

If the thickness of the oxide film formed in the annealing treatment exceeds about 70 A, it will take on a dull brown color, and if it becomes even thicker, it will become copper red, so excessive oxidation should be avoided.
For this purpose, it is preferable to carry out the process in a reducing atmosphere containing about 0.5 to 7.0% (by volume) of carbon oxide (CO). Also,
The treatment temperature is preferably about 300° C. or higher from the viewpoint of strain removal effect and formation of an oxide film. In this annealing treatment, the coating film reacts with the copper of the product base to form metal spikes.

This metal soap acts as a catalyst to suppress the reduction of the formed oxide film, and has the function of making the oxide film uniform and dense. The layer thickness is approximately 40 to 70 mm due to the above annealing treatment.
A uniform and dense oxide film with a bright color of 0A is formed.

This oxide film is extremely stable, and even if the product is left in the air for a long time, it will not lose its bright color and will maintain its beautiful appearance. Next, the present invention will be specifically explained with reference to Examples.

Example Using trichlorethylene as a chlorinated organic solvent, a coating solution was prepared by dissolving semi-drying oil or non-drying oil as a solute (coating film component) in various proportions, and this was then phosphorized by dipping. Deoxidized copper pipe material (diameter 9.52 mmφ, wall thickness 0.35
mm1 length 350 mm) to form a coating film (immersion time was 3 minutes in each case).

The coating film was left to stand for about 1 hour to remove the solvent, and then subjected to an annealing treatment. The annealing treatment is performed using CO2. O
% in a reducing atmosphere furnace at a temperature of 500°C.
This was done by holding for 5 hours. Each of the obtained tube products was left in a hot and humid atmosphere at a temperature of 60°C and a relative humidity of 90% (4) as is, or [F]) wrapped in polysheet, left for 2 hours, and left to stand. After that, each product was examined for discoloration. In addition, as a comparative example, a pipe material without a coating film was applied, and a coating film was applied with a coating liquid prepared using drying oil as a coating component (the solvent was trichlorethylene).
A storage test was conducted on a product obtained by subjecting it to the same treatment as above. The number of test material products was 10 each. Note that rapeseed oil and castor oil were used as the semi-drying oil and non-drying oil, respectively, and linseed oil was used as the drying oil. The test results are shown in Table 1.

In the table, (4) and [F]) in the [Leave test] column indicate the leave test conditions of (4) and (B) above, respectively. Regarding the determination of the presence or absence of discoloration, those with slight discoloration or discoloration were visually observed as "discoloration present", and those with brightness were assessed as "no discoloration". The numbers in the same column indicate the number of products of each sample material. As shown in Table 1 above, in products that are not coated, discoloration occurs in all of the test materials, and in products that use drying oil as a coating component, even if the concentration of the coating component is increased. More than half of the sample materials had discoloration. On the other hand, with the products in which a coating film was formed using a coating liquid containing a predetermined amount of semi-drying oil or non-drying oil using the method of the present invention, none of the test materials showed any discoloration and maintained its original bright state. It turns out that it does.
As described above, the copper or copper alloy products obtained by the method of the present invention have a dense and stable oxide film with excellent discoloration prevention ability, do not discolor at all even under high temperature and high humidity conditions, and can last for a long time. It never loses its shiny and beautiful appearance.

Claims (1)

[Claims] 1. A solution prepared by blending 0.2 to 10.0% (volume) of semi-drying oil or non-drying oil in a chlorinated organic solvent is applied to the surface of copper or copper alloy, and then dried. After removing the solvent, the copper or copper alloy product is annealed at a temperature of 300°C or higher in a reducing atmosphere furnace containing 0.5 to 7.0% (by volume) of carbon monoxide. Manufacturing method. 2. The first above, characterized in that the semi-drying oil is rapeseed oil.
Manufacturing method described in Section. 3. The production method according to item 1 above, wherein the non-drying oil is castor oil. 4. The production method according to any one of the above items 1 to 3, wherein the chlorinated organic solvent is trichlorethylene.