| 摘要 |
PROBLEM TO BE SOLVED: To prevent breeding or blooming under use and improve long-term electric insulating property by vulcanization molding a power cable rubber composition as starting material, and then dipping the molded rubber in silicone oil within a specified temperature range. SOLUTION: A power cable rubber composition consisting of 100 pts.wt. of rubber component, 0.8 pts.wt. of a vulcanizing agent, 4 pts.wt. of zinc white, 0.8 pts.wt. of a vulcanization accelerating aid, 0.5 pts.wt. of an antioxidant, and 0.5 pts.wt. of a lubricant is prepared. This rubber composition is press- vulcanized under a vulcanization condition of 160 deg.C×30 min, and dipped in silicone oil of 50-100 deg.C for two days to provide a dipped molded rubber. After the dipped molded rubber is repeatedly subjected to a heat cycle (RT, 90 deg.C) in gas, presence of bleeding or blooming and the insulating resistance at a DC voltage of 1000 V are measured. According to the result, no bleeding or blooming is observed, the insulating resistance is as high as 5.0×10<14> (Ω, cm), and the long-term insulating property can be improved.
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