co-extrudable screening layer for medium or high tension cable - based on polyblend contg. elastomer unaffected by stabiliser migration

摘要

Coextrudable conductive layer for plastics-insulated medium or high tension cable consists of a mixt. of a polyblend of a polymer (mixt.) (I) with a m. range >=120 degrees C and an elastifying rubbery polymer-based component(II), made conductive by known additives, e.g. C black and/or graphite. (I) is pref. HDPE (density >=0.94 g/cm3) or isotactic polypropylene and (II) high-mol. polyisobutylene (mol. wt. 100,000-150,000), EPM or EP rubber. Conductivity is imparted by highly structured, nonhygroscopic C black, pref. in an amt. of 20-90 (over 50) pts./100 pts. polymer. The mixt. also contains 1-10 pts. voltage stabiliser/100 pts. polymer. The blend is useful as inner or outer screening layer and is not or hardly effected by stabiliser migration. It has good electrical and mechanical properties, even at varying temps.