Patent ID: 8586159

Claim:
A breathable, heat-sealable, composite film comprising a perforated polymeric substrate layer having a first and second surface and disposed on a surface of the substrate layer an unperforated barrier layer that is permeable to gaseous water and that comprises a polymer selected from the group consisting of copolyesterethers, polyesters comprising terephthalic acid and ethylene glycol, and polyamides, wherein: (i) the thickness of the unperforated barrier layer is no more than 8 μm; and (ii) the perforated substrate layer has a degree of perforation of from about 0.1 to about 78%, wherein the perforations have an average diameter of between 0.05 and 1.5 mm; the composite film having a WVTR of at least 60 g/m 2 /day.