Method and apparatus for spinning a web of mixed fibers, and products produced therefrom

A coalescing filter element formed from a homogeneous web of mixed fibers, some of which comprise a material selected from the group consisting of homopolymers and copolymers of fluorocarbon polymers and chlorinated fluorocarbon polymers, and the remainder of which comprise a bonding polymer, said fibers comprising said material being bonded to each other at spaced points of contact by said bonding polymer to form a porous matrix, wherein said fibers comprising said material are bicomponent fibers comprising a core of a polyolefin and a sheath of said material, and said bonding polymer fibers are bicomponent fibers comprising a core of said polyolefin and a sheath of polyethylene terephthalate, said web of mixed fibers being produced by a fiber spinning process comprising the steps of

• providing at least two independent sources of polymer materials,
• feeding said polymer materials from each of said independent sources into a spinning device including at least one element defining a plurality of spinneret orifices,
• maintaining said polymer materials in mutually separated distribution paths in said spinning device at least until said polymer materials approach the inlets to the spinneret orifices in said element,
• flowing at least some polymer material from one of said independent sources into selected ones of the spinneret orifices in said element and flowing at least some polymer material from another of said independent sources into different selected spinneret orifices in said element under conditions causing extrusion from the spinneret orifices of said element of a homogeneous web of fibers, at least some of said fibers formed from said web of fibers having different characteristics from other fibers formed from said web of fibers, wherein said polymer materials from said independent sources comprise at least three different polymers, portions of one of said polymers being fed to every spinneret orifice, portions of each additional polymer being fed only to said selected spinneret orifices to be combined in the selected spinneret orifices with said one polymer and extruded therefrom as multiple-component fibers, whereby said web of fibers comprises a mixture of multiple-component fibers, some of which comprise said one polymer combined with one of said additional polymers, and others of which comprise said one polymer combined with a different one of said additional polymers, and wherein said mixture of multiple-component fibers comprise a mixture of bicomponent sheath/core fibers having a common core-forming polymer and different sheath-forming polymers, and the ratio of said different bicomponent fibers being substantially uniform throughout said web of mixed fibers.