3m Innovative Properties Company

Shannon K Hughes

William Blake Kolb

Robert A Yapel

James Stephen Mrozinski

Robert Steven Kody

Myles Lee Brostrom

A method and apparatus for producing microporous films. The method utilizes a casting surface and a condensing surface. The condensing surface is spaced from the casting surface to form a gap. The distance between the surfaces forming the gap is relatively small and is preferably less than 3 cm. A material, capable of forming microporous films through thermally induced phase separation processes, is cast onto the casting surface, preferably through conventional extrusion practices. The material contains at least one evaporative component that generally flashes off upon formation of the microporous material and condenses on the condensing surface.

Extruder with condenser

Process of making microporous film

Microporous materials and articles are disclosed. The microporous materials contain a crystallizable propylene-containing polymer, a beta-nucleating agent, and a diluent that is miscible with the polymer at a temperature above the melting temperature of the polymer and that phase separates from the polymer at a temperature below the polymer crystallization temperature. The invention is also directed to methods of forming the microporous material using thermal induced phase separation and subsequent processing.

Microporous materials and methods of making the same

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Minneapolis, MN, United States of America

Shannon K Hughes