Patent ID: 6013151
Filing Date: 2000-01-11
Classification: B29C,B29K,B32B,C08J,C08K,C08L

Abstract:
A high speed method of making a microporous thermoplastic film comprisingmelt blending a composition comprising(a) about 35% to about 45% by weight of a linear low density polyethylene,(b) about 3% to about 10% by weight of a low density polyethylene,(c) about 40% to about 55% by weight calcium carbonate filler particles, and(d) about 2% to about 6% by weight of a triblock copolymer of styrene selected from the group consisting of styrene-butadiene-styrene, styrene-isoprene-styrene, and styrene-ethylene-butylene-styrene, and blends thereof,extruding said melt blended composition into a nip of rollers with an air knife to form a film at a speed on the order of at least about 550 fpm to about 1200 fpm without draw resonance, andapplying an incremental stretching force to said film at said speed along lines substantially uniformly across said film and throughout its depth to provide a microporous film.