ETHYLENE-AROMATIC VINYL COMPOUND COPOLYMER FOR ELECTRIC INSULATOR, COMPOSITION FOR ELECTRIC INSULATOR, ELECTRIC WIRE-COVERING MATERIAL COMPRISING THE SAME COPOLYMER AND ELECTRIC WIRE

摘要

PROBLEM TO BE SOLVED: To obtain the subject copolymer having a specific composition and crystallinity and reduced breakdown voltage drop caused by repeated impulses an useful for an electric wire, etc., by copolymerizing ethylene with an aromatic vinyl compound by using a metallocene catalyst. SOLUTION: This ethylene.aromatic vinyl compound copolymer contains 0.05-3mol% of a structural unit derived from an aromatic vinyl compound and has >=40% crystallinity and reduced breakdown voltage drop caused from repeated impulses with enlarged applying times of the repeated impulses till generating the insulation breakdown and useful for a covering materiel of an electric wire, etc. The copolymer is obtained by ethylene with an aromatic vinyl compound (e.g. styrene) in the presence of a metallocene catalyst comprising a bridge-type metallocene compound [e.g. isopropylidene bis(indenyl) zirconium dichloride].