Process for preparing a microporous polymer film

A process for the preparation of an open-celled microporous, polymer film. The improved process comprises the heat relaxing of a microporous polymer film which is formed from a non-porous, crystalline, elastic polymer film which has been uniaxially cold stretched at a temperature in the range of bet...

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Bibliographische Detailangaben
Hauptverfasser:	BRAZINSKY, IRVING, COOPER, WILLIAM M, GOULD, ARNOLD S
Format:	Patent
Sprache:	eng
Schlagworte:	AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING CHEMISTRY COMPOSITIONS BASED THEREON GENERAL PROCESSES OF COMPOUNDING METALLURGY ORGANIC MACROMOLECULAR COMPOUNDS PERFORMING OPERATIONS PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE SEPARATION SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR SHAPING OR JOINING OF PLASTICS THEIR PREPARATION OR CHEMICAL WORKING-UP TRANSPORTING WORKING OF PLASTICS WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL WORKING-UP
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Beschreibung
Zusammenfassung:	A process for the preparation of an open-celled microporous, polymer film. The improved process comprises the heat relaxing of a microporous polymer film which is formed from a non-porous, crystalline, elastic polymer film which has been uniaxially cold stretched at a temperature in the range of between about -20 DEG C. and a temperature 25 DEG C. below the crystalline melting temperature of the polymer film, followed by hot stretching, in the same direction, the cold-stretched film at a temperature in the range of between about 25 DEG C. below the crystalline melting temperature of the polymer film and 5 DEG C. below the crystalline melting temperature of the polymer film. The heat relaxing step comprises exposing the film under tension to a temperature in the range of between about 40 DEG C. below the crystalline melting temperature of the polymer film and 5 DEG C. below the crystalline melting temperature of the polymer film, such that the maximum dimension in the direction of stretch, of the cold and hot stretched microporous film is reduced.