Patent ID: 9589700
Date: 2017-03-07
CPC Classifications: C08K,C08L,H01B,Y10T

Claim:
1. A cross-linked polyethylene composition for a power cable insulator comprising: (A) 100 parts by weight of a polyethylene base resin; (B) 0.1 to 0.6 parts by weight of a hindered phenol-based antioxidant; (C) 1 to 4 parts by weight of a crosslinking agent; (D) 0.2 to 1.0 parts by weight of magnesium oxide surface treated with silane, which has an average particle size of less than 1 μm; and (E) 0.1 to 1.0 parts by weight of a scorch inhibitor, wherein the polyethylene base resin (A) is an ethylene homopolymer polymerized by a free radical initiation reaction at a high pressure of 1,000 bar or more in a high-pressure tubular or autoclave reactor, wherein the hindered phenol-based antioxidant (B) is the only antioxidant included in the composition, and the hindered phenol-based antioxidant (B) is only one compound selected from the group consisting of 4,4′-thiobis(2-t-butyl-5-methylphenol), 2,2′-thio diethyl bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate], pentaerythrityl-tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate], 4,4′-thiobis(2-methyl-6-t-butylphenol), 2,2′-thiobis(6-t-butyl-4-methylphenol), octadecyl-[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate], triethyleneglycol-bis-[3-(3-t-butyl-4-hydroxy-5-methylphenol)propionate], thiodiethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 6,6′-di-t-butyl-2,2′-thiodi-p-cresol, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-xylyl)methyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione and dioctadecyl 3,3′-thiodipropionate, wherein a weight ratio of the scorch inhibitor (E) to the magnesium oxide surface-treated with silane (D) is 1:0.3 to 1:4, and wherein the cross-linked polyethylene composition has a water tree growth rate of 0.1 or less measured by ASTM D6097.