High speed method of making microporous film products
AssigneeClopay Plastic Products Company, Inc.
InventorsPai-Chuan Wu, Leopoldo V. Cancio, Girish K. Sharma
Life of this patent
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Abstract
Microporous film products permeable to moisture vapor and which act as barriers to liquid are made by a high speed method. Such microporous products are made at speeds in the order of above 500 fpm to about 1200 fpm. Thermoplastic polymers are melt blended to contain about 35% to about 45% by weight of a linear low density polyethylene, about 3% to about 10% by weight of a low density polyethylene; about 40% to about 55% by weight calcium carbonate filler particles, and about 2% to about 6% by weight of a triblock polymer of styrene.
Claims37
A high speed method of making a microporous thermoplastic film comprising
- melt 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, and
- applying 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.
A high speed method of making a microporous thermoplastic film comprising
- melt 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,
- slot die extruding said melt blended composition into a nip of rollers with an air knife to form a film of about 0.5 to about 10 mils in thickness at speeds on the order of at least about 750 fpm to about 1200 fpm without draw resonance,
- cooling said film to ambient temperature, and
- applying an incremental stretching force to said cooled film at said speed along lines substantially uniformly across said film and throughout its depth to provide a microporous film.
Dependencies are inferred from the claim text.