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Abstract

A nonwoven composite structure is provided which has at least two melt-extruded nonwoven layers: (A) a first layer which includes at least a portion of a first nonwoven web; and (B) a second layer which includes at least a portion of a second nonwovfen web; in which, (1) the boundary between any two adjacent melt-extruded nonwoven layers is indistinct in that fibers at or near the surfaces of such adjacent layers are significantly intermingled; (2) the fibers of at least one of such first and second layers are prepared by melt extrusion through a die at a shear rate of from about 50 to about 30,000 sec.sup.-1 and a throughput of no more than about 5.4 kg/cm/hour of a mixture of an additive and a thermoplastic polymer, which additive imparts to the surfaces of the fibers, as a consequence of the preferential migration of the additive to the surfaces of the fibers as they are formed, at least one characteristic which is different from the surface characteristics of fibers prepared from the thermoplastic polymer alone, said preferential migration taking place spontaneously upon the formation of the fibers without the need for a post-formation treatment of any kind; (3) the additive present in any melt-extruded nonwoven layer does not migrate to an adjacent layer to a significant degree in use, so that the surface characteristics of each layer remain substantially as originally prepared; and (4) the composite has been pattern bonded by the application of heat and pressure.

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First Claim