ELECTRICAL INSULATING MATERIAL COMPOSED OF EXPANDED POLYPROPYLENE FILM WITH IMPROVED ELECTRICAL CHARACTERISTICS

摘要

An electrically insulating material comprises a film obtained by at least uniaxially stretching an extruded polypropylene sheet containing from 0.05 to 10,000 ppm by weight of a polymer of a 3-branched alpha -olefin having 6 or more carbon atoms and/or a vinylcycloalkane having 6 or more carbon atoms in terms of a monomer unit thereof. The electrically insulating material has a high dielectric breakdown voltage and is suitable for producing small-sized condensers.