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Method of making a breathable and liquid impermeable web

  • US 6,605,172 B1
  • Filed: 09/25/2000
  • Issued: 08/12/2003
  • Est. Priority Date: 09/30/1999
  • Status: Expired due to Term
First Claim
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1. A method of making a breathable web comprising:

  • a. feeding a web of a polymeric film having a pore forming agent dispersed therein in a web movement direction to a pair of opposed, interengaged forming rolls, wherein each forming roll includes a plurality of axially spaced, circumferentially extending, alternating radial teeth and intervening grooves, and wherein the teeth of one roll are opposite from and extend into the grooves of the opposed roll; and

    b. passing said web between said forming rolls while said web is at a temperature of about 25°

    C. to about 120°

    C. and an engineering strain rate of about 50 s

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    to about 1650 s

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    , and mechanically modifying said web to form a breathable web having an MVTR of at least about 2000 g/m2/24 hr, a dynamic fluid impact value of less than about 10 g/m2, a bubble pressure of at least about 45 psi, and an air flow of at least about 2 liters/m2/s.

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