PURPOSE: To provide an electric insulator for electric wire/cable with which water tree formation is remarkable suppressed by adding a specified amount of a specified aminosilane to polyethylene or ethylene-type copolymer and carrying out crosslinking treatment.
CONSTITUTION: To 100 pts. by wt. of polyethylene, ethylene-type copolymer, or its mixture, 0.005-1.0 pts. by wt. of aminosilane having a formula (the total carbon number of R1, R2, R3, R4, R5, R6 is 8 or more; R1, R2 stands for H or hydrocarbon group except phenyl and substituted phenyl; R1-R6 may contain O, N, S, or Si in a part of the structure) is added. The resulting composition is crosslinked by a method using a crosslinking agent such as dicumyl peroxide to give an electric insulator for electric wire/cable. Using the electric insulator, formation of water tree especially bowtie tree is sufficiently suppressed and no bloom formation occurs even if there are voids, foreign substances, and defects that irregularity exists in the interface of the insulator and a semiconductive layer.
Takanori Yamazaki
Kiyoshi Watanabe
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