METHODS OF MAKING THICK, HIGHLY ORIENTED, OPAQUE, LOW-DENSITY, MICROPOROUS POLYOLEFIN FILMS AND THE FILMS MADE THEREBY

摘要

A method of making a polyolefin film in accordance with this inventionincludes the steps of: blending a propylene block copolymer with a betanucleating agent; extruding a film layer from the blend and providing a totalarea draw ratio in excess of 20, where at least one part of the stretchingoccurs at 120~C, for forming the film with a density no greater than0.40g/cm~ and a thickness greater than 160 gauge. The film also constitutes apart of this invention.