JPS6025504B2 - Rust prevention treatment method for copper, silver or their alloys - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a rust-preventing treatment method for copper, silver, or their alloys, and in particular, to provide a corrosion-resistant coating on the surface of these metals or alloys that can withstand harsh conditions. That is.

In general, in order to improve the corrosion resistance of copper, silver, or their alloys, such as tin-containing copper, silver-containing copper, brass, bronze, and copper-containing silver, etc., it has been widely practiced for a long time to apply an anticorrosive coating to the surface of the copper, silver, or their alloys. For example, chromic acid or dichromic acid is immersed in an aqueous solution to form a corrosion-resistant coating.

However, since many of these methods are harmful to the human body, in recent years, methods using non-toxic penzotriazole or its derivatives have been mainly used. However, this method cannot be said to be sufficient in terms of improving corrosion resistance. That is, although it is practically effective against oxidation under heated conditions, it cannot maintain sufficient corrosion resistance against sulfide corrosion that occurs in harsh environments where sulfur or sulfur compounds coexist. Recently, sulfide corrosion due to air pollution is becoming more and more of a problem, and sulfide corrosion has been a traditional problem in the electrical industry due to the use of insulating oil.

In other words, copper, silver, or their alloys are widely used industrially because they are excellent conductors, but these metals or alloys are used, for example, in transformers by immersing them in insulating oil that also serves as a cooling medium. In this case, the normal insulating oil is JIS-C232
Since it is a class of mineral oil designated as 1, it contains a small amount of sulfur compounds, so the above metals or alloys will undergo sulfide corrosion, particularly at high temperatures, and will corrode significantly, forming a black or porous thick sulfide film. , which poses a major practical obstacle. Therefore, in harsh corrosive environments, copper, silver, or their alloys are plated with tin of 1 to 10 degrees, or coated with enamel of 10 to 50 degrees, but these methods are complicated and time consuming. This required a great deal of expense.

The present invention has been made as a result of extensive research in view of the current situation, and has resulted in the discovery of a novel anti-corrosion coating treatment method.

That is, the present invention is characterized in that after adhering penzotriazole to copper, silver, or an alloy thereof, it is heated for 18 minutes or more in an oxygen-containing atmosphere of 100 to 160 qo. Among the penzotriazoles used in the present invention, penzotriazole is a compound to which the following benzene ring triazole group is added.

However, x is a substituent such as H or a hydrocarbon.

It is thought that this is because copper or silver binds to the active hydrogen position of this triazole to form a strong chelate compound.
For example, the above compound film is formed by contacting the metal by immersing it in a solution of 0.01 to 5 M% penzotriazole in water or a polar solvent.

Furthermore, penzotriazole is a general term for derivatives obtained by adding organic amines, organic acids, or amides to the above compounds. These additional bonds are said to be related to the active hydrogen of the triazole group, as shown in Hakama Publication No. 50-13225, Japanese Patent Publication No. 50-13750, and Special Publication No. 51-33909, but as mentioned above, a chelate compound film is formed. It is assumed that the Furthermore, surfactants such as higher fatty acid amides, higher aliphatic amines, or polyoxyethylene additives may be added to these penzotriazoles. In the method of the present invention, after the penzotriazole is deposited as described above, excess deposits are washed and removed with water, solvent, etc. as necessary, but if this continues, a sufficient corrosion-resistant film cannot be formed.

Next, heat treatment is required in an oxygen-containing atmosphere such as air at 100 to 160 qo. In this case, even if heated in an oxygen-free atmosphere such as pure nitrogen or argon, the corrosion resistance not only does not improve, but on the contrary, it significantly decreases. Furthermore, if the temperature is less than 100°C, the corrosion resistance effect will not be exhibited, and if it exceeds 160°C, the coating will decompose and be consumed.
0 is preferred. In addition, although the treatment time was limited to 15 minutes or more, if the treatment time is less than 15 minutes, it is too short and only dries the coating film and no effect of the heat treatment can be obtained and corrosion resistance will not improve. . Note that as the treatment time becomes longer, the corrosion resistance gradually improves.

The reason why corrosion resistance is significantly improved by this heat treatment is not clear, but it is assumed that this is due to the densification and strengthening of the film in which oxygen is involved.

In addition, when bonded in penzotriazole, usually 2
The chelate or adsorption film of 0 to 50△ is formed,
In order to withstand the harsh sulfiding atmosphere, a film of 808 or higher is required. Next, examples of the present invention will be described.

Example 1 After drying 0.5 x 15 tough pitch steel strips in methanol-toluene containing 1.5% methyl benzotriazole at 40 qo, they were placed in an atmospheric furnace at 130 qC for 2 hours. A copper strip according to the method of the present invention was obtained by heat treatment (referred to as the product of the present invention [1}).

In order to use the present invention '11 as a pole transformer conductor, No. 2 insulating oil (13
As a result of testing the corrosion resistance by immersing it in 030) for one week, only a few spots of black sulfurized parts were observed, and it was sufficiently usable.

In addition, since the pole transformer operates at a temperature of 50 to 90°C, it was confirmed that the product of the present invention does not suffer from corrosion.

Comparative Examples 1 and 2 The copper strip used in Example 1 was left untreated (Comparative Example 1), and the copper strip was diluted in penzotriazole in the same manner as in Example 1 (Comparative Example 2
) was subjected to the corrosion resistance test in the same manner as above, and the first comparative example developed a thick peelable black film over the entire surface.
A part of it was removed.

In addition, Comparative Example 2 had blackening in spots over the entire surface.
Example 2 A silver-containing copper strip (0.3 x 20 ratio, etc.) was soaked in an aqueous solution containing 4% penzotriazole triethanolamine salt and a small amount of nonionic activator at 2 and 0 for 19 hours, and then Washed with water and dried.

Next, the product was placed in a 15,000°C atmospheric furnace for 3 minutes and heat-treated to obtain a silver-containing copper strip according to the method of the present invention (referred to as the product of the present invention (2)). When the product (2) of the present invention was tested for corrosion resistance in the same manner as in Example 1, only a portion of the product was blackened and no abnormality was observed.

Example 3 A tinned steel strip (0.18 x 200 bars) was placed in trichloroethylene containing 0.2% penzotriazole at 15°C.
After soaking for 19 seconds, it was washed with water and dried.

Next, a heat treatment was performed for 15 minutes at 15,000 yen in a pure oxygen stream to obtain a tin-filled copper strip according to the method of the present invention. (referred to as the present invention product (3)) The present invention product '3' was dissolved in 0.1N hydrochloric acid 60c.
1 containing a mixture of c and 7.5 ml of soda sulfide 10 cc
0 When a hydrogen sulfide resistance test was carried out by keeping the sample in a desiccator for 1 hour, only partial discoloration occurred.

Further, the copper sulfide coating was measured by constant current cathode reduction and found to have an average thickness of 80A. Comparative Examples 3 and 4 The same tin-containing steel strip as in Example 3 without any treatment (Comparative Example 3) and the same strip in trichloroethylene containing 0.2% penzotriazole as in Example 3. Inside 1
After soaking in sand for 9 minutes, it was washed with water and dried.

Next, heat treatment was carried out at 15,000 Celsius for 15 minutes in an argon stream to obtain comparative example product t4} tin-filled steel. When the copper strip thus obtained was subjected to a hydrogen sulfide test in the same manner as in Example 3, the color changed to blackish brown or purple, and the average film thickness was 3200△(
It was a comparative example product [Su, 2400A (comparative example product {4}). As detailed above, according to the method of the present invention, it was possible to significantly improve the corrosion resistance of copper, silver, or their alloys due to hydrogen sulfide, etc.

Claims (1)

[Claims] 1. A method for anti-corrosion treatment of copper, silver or alloys thereof, which comprises adhering benzotriazoles to copper, silver or alloys thereof, and then heating the mixture for 15 minutes or more in an oxygen-containing atmosphere at 100 to 160°C.