Self-bonded nonwoven web and porous film composites

A self-bonded nonwoven web and porous film composite having a basis weight in the range of about 1.0 to about 6.0 oz/yd.sup.2 comprising,

• at least two layers of a uniform basis weight self-bonded, fibrous nonwoven web having a basis weight of about 0.25 oz/yd.sup.2 or greater and a Basis Weight Uniformity Index of 1.0.+-.0.05 determined from average basis weights having standard deviations of less than 10% comprising a plurality of substantially randomly disposed, substantially continuous thermoplastic filaments wherein said filaments comprise a thermoplastic selected from the group consisting of polypropylene, a blend of polypropylene and polybutene and a blend of polypropylene and linear low density polyethylene and said webs are adhered to
• at least one layer of an oriented vapor-permeable polymeric porous film having a basis weight of 0.5 oz/yd.sup.2 or greater comprising a blend of about 70 to 100 wt % of a polypropylene and about 30 to 0 wt % of an ethylene-propylene copolymer having an ethylene content of about 10 to about 50 wt % and formed by the steps of:
• (a) forming a homogeneous blend of a propylene-based resin and about 0.5 to about 10 ppm of a nucleating agent capable of producing beta-spherulites,
• (b) extruding the blend into a film having a thickness of about 0.01 to about 0.4 millimeters on a cast film line having a chill roll temperature of about 90.degree. to about 130.degree. C.,
• (c) cooling the film below the crystallization temperature of the propylene-based resin to form at least 20 wt % beta-spherulites in the film,
• (d) extracting beta-spherulites corresponding to at least 15 wt % of the blend from the cast film by immersing the cast film in a toluene bath at a temperature of about 85.degree. to about 95.degree. C. for a time period of 10 minutes or less to form a porous film and drying the porous film at a temperature of about 15.degree. to about 110.degree. C. for 20 minutes or less, and
• (e) orienting the porous film be heating the porous film at a temperature of about 115.degree. to about 135.degree. C. for a time period of about 2 to about 20 seconds and stretching the heated porous film in at least one direction at a stretch ratio of about 1.5 to about 7.5 to form the oriented porous film.