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Microporous films

  • US 5,198,162 A
  • Filed: 06/13/1989
  • Issued: 03/30/1993
  • Est. Priority Date: 12/19/1984
  • Status: Expired due to Fees
First Claim
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1. A method of making a polymeric film which comprises melt processing into a film of polymer composition comprising:

  • (a) a halopolymer in which the repeat units are --(Cn H2n)-- and --(Cm X2m)-- where each X independently represents fluorine or chlorine and the values of n and m are greater than one and less than six; and

    (b) an extractable component comprising an extractable salt and an extractable polymer which are substantially insoluble in said halopolymer, said extractable polymer migrating preferably toward the surface of said film during said melt processing;

    and subsequently extracting at least some of the extractable component so as to produce a film having a porosity of not less than about 20% by volume, said extraction of said extractable polymer imparting surface porosity to said film.

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