Novel porous fabric

Abstract

There is described a process for producing a novel porous fabric having at least 100,000 surface perforations per square inch by the biaxial stretching at ambient temperatures of a sheet of a composite fiber-film substrate formed by hot calendaring, inter alia, a laminate of a woven or non-woven web of fibers having a residual elongation of at least 40% and a synthetic polymeric film material constituting at least 20% by volume of the composite fiber-film substrate. Stretching of the composite fiber-film substrate is effected by passage through interdigitating grooved rollers having grooves spaced at a distance of less than one millimeter times the web basis weight in grams per square meter with concomitant control of the velocity of introduction of the composite fiber-film substrate into the nip of the grooved rollers to substantially the identical surface velocity of the grooved rollers. Biaxial stretching is effected to at least a stretch ratio such that a web of the fibers and film of the synthetic polymer taken individually and biaxially stretched exhibit a difference of at least 5.degree. in the aqueous contact angle and a difference of at least 5000 psi in the initial tensile modulus. The novel porous fabric is comprised of elongated fibers embedded in a film substrate surface with openings of at least 100,000 perforations per square inch and is useful as a leather substitute, synthetic paper and the like.

Dependencies are inferred from the claim text.