US 6,605,172 B1 · Method of making a breathable and liquid impermeable web

Abstract

A method is disclosed for modifying the physical characteristics of a web which involves passing the web between at least one pair of interengaged rolls to incrementally stretch the web, and then withdrawing the incrementally stretched web from between the rolls under tension. A web modified according to the disclosed method has desirable breathability and liquid impermeability, as well as extensibility and a soft, cloth-like textured surface. One embodiment of the present invention provides a breathable web comprising a microporous film exhibiting an MVTR of at least about 2000 g/m2/24hr, a dynamic impact value of less than about 10 g/ m2, a bubble pressure at least about 45 psi, and an air flow of at least about 2 liters/m2/s.

Claims15

Dependent claims

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−1 to about 1650 s−1, 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.

Dependencies are inferred from the claim text.

Method of making a breathable and liquid impermeable web

Life of this patent

Method of making a breathable and liquid impermeable web

Life of this patent

Abstract

Claims15