JPS6223034B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to stabilizer compositions that do not discolor copper. It is well known that crosslinked polyethylene resins using organic peroxides as crosslinking agents are widely used in applications that come into contact with copper, such as electrical insulation coating materials for power cables and communication cables. Antioxidants are commonly used in such cross-linked polyethylene resins to prevent their oxidative deterioration.
It is also well known that a copper discoloration inhibitor is used in combination for the purpose of preventing discoloration of copper in contact with crosslinked polyethylene resin. Various antioxidants are known for this purpose, but the representative one is 4,4'-thiobis(3-methyl-6-t-butyl), which has excellent antioxidant performance and electrical properties. Various agents are known as discoloration inhibitors for copper, and benzotriazole is a typical example. However, 4,4'-thiobis(3-methyl-6-t-butylphenol) containing benzotriazole has excellent oxidative deterioration prevention performance and shows good copper plate corrosion prevention performance in copper plate corrosion tests. 4,4′-thiobis(3
-Methyl-6-t-butylphenol) has the disadvantages that the product color becomes light yellowish brown, or it undergoes further discoloration over time during storage and becomes yellowish brown, and the heat melting color changes to brown. For this purpose, 4,4'-thiobis(3-
When methyl-6-t-butylphenol is used as a stabilizer composition in a crosslinked polyethylene resin, the resin itself is also colored, and the commercial value of the resin is reduced, especially when high whiteness is required. There is a problem in that the amount of energy decreases significantly, and an improvement has been strongly desired. Therefore, the present inventors conducted extensive research to improve the above points, and found that 4,4'-thiobis(3-methyl-6-t-butylphenol) has a chain polyhydric carboxylic acid. By incorporating a small amount of alkali metal salts or ammonium salts (hereinafter simply referred to as chain polyvalent carboxylates), the color of the product remains white, does not discolor over time, and almost never melts due to heat. It is completely unexpected from conventional knowledge that it not only remains white and has excellent anti-oxidation properties, but also does not discolor copper and has excellent copper corrosion prevention properties. After discovering this fact, we have completed the present invention. That is, the present invention provides 4,4'-thiobis(3-methyl-6-t-butylphenol) with one or more linear polyhydric carboxylic acid salts of 0.0001 to 1.0.
The object of the present invention is to provide a stabilizer composition that does not cause discoloration of copper, which is formulated by weight%. Examples of chain polycarboxylic acid salts used in the present invention include alkali metal salts (e.g., sodium salts and potassium salts) and ammonium salts of oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, and citric acid. In particular, alkali metal salts and ammonium salts of oxalic acid, tartaric acid, and citric acid are preferred. Furthermore, the most preferred among these is the trisalt of citric acid, especially the trisodium salt. The amount of the chain polycarboxylic acid salt added in the present invention is 0.0001 to 1.0% by weight, preferably 0.001 to 0.1% by weight, based on 4,4'-thiobis(3-methyl-6-t-butylphenol). It is. If the amount added is less than 0.0001% by weight, there is almost no copper corrosion prevention effect or coloring prevention effect, and if it exceeds 1.0% by weight, the coloring prevention effect is excellent but the copper corrosion prevention effect is poor. There are no particular restrictions on the method of addition, and it may be blended in any method and may be added to any step in the manufacturing process of 4,4'-thiobis(3-methyl-6-t-butylphenol). The chain polyvalent carbon salts may be used alone or in combination of two or more. Note that there is no problem in adding a conventionally known copper discoloration inhibitor such as benzotriazole to an extent that does not impair the characteristics of the stabilizer composition of the present invention. Furthermore, free chain polycarboxylic acids may also be added to the extent that they do not impair the characteristics of the stabilizer composition of the present invention. Next, the present invention will be explained in detail by way of examples. Example 1 Each stabilizer composition was obtained by adding a predetermined amount of each additive listed in Table 1 to 4,4'-thiobis(3-methyl-6-t-butylphenol), and the initial hue, When tests were conducted on discoloration over time, thermal melting color, and copper plate corrosion, the results shown in Table 1 were obtained.

[Initial hue (APHA)]

The initial hue was expressed by the APHA value of a 10% methanol solution. [Discoloration over time (APHA)] The degree of discoloration over time was expressed by the APHA value (10% methanol solution) after each sample was kept in a gear oven at 100°C for 48 hours. [Thermal melting color (Gardner)] Thermal melting color after heating at 180°C for 60 minutes was expressed as Gardner hue. [Copper plate corrosion test] A copper plate corrosion test was conducted according to the test tube method of JISK2513 petroleum products copper plate corrosion test method. However, immersion conditions: 50℃, 96 hours Sample concentration: 10w/v%
(Ethyl alcohol was used as a solvent) The degree of discoloration of the copper plate was compared and determined using the copper plate corrosion standard specified in ASTM D/30 IP/54. Example 2 Trisodium citrate was added to 4,4′-thiobis(3-methyl-6-t-tylphenol) and
When 0.0001, 0.001, 0.01, 0.1, 1.0, and 5.0% by weight were added, initial hue, discoloration over time, thermal melting color, and copper plate corrosion tests were conducted, and the results shown in Table 2 were obtained.

[Table] Example 3 Initial hue of 4.4′-thiobis(3-methyl-6-t-butylphenol) to which trisodium citrate and disodium oxalate were added alone or in combination as shown in Table 3. When tests were conducted on discoloration over time, thermal melting color, and copper plate corrosion, the results shown in Table 3 were obtained.

【table】

[Table] Example 4 Initial hue of 4,4'-thiobis(3-methyl-6-t-butylphenol) to which trisodium citrate and benzotriazole were added alone or in combination as shown in Table 4. When tests were conducted on discoloration over time, heat melting color, and copper plate corrosion, the results shown in Table 4 were obtained.

【table】

【table】

Claims (1)

[Claims] 1 Copper made by blending 0.0001 to 1.0% by weight of one or more alkali metal salts or ammonium salts of chain polycarboxylic acids to 4.4'-thiobis(3-methyl-6-t-butylphenol). Stabilizer composition that does not change color.