| 摘要 |
<p>Sheath-core bicomponent fibers(10) comprising a core (14) of a low-cost, high strength, thermoplastic material, preferably, polypropylene, completely covered with a sheath (12) formed preferably of plasticized cellulose acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol or ethylene-vinyl alcohol copolymer, are produced, preferably melt blown to an average diameter of 10 microns or less, and formed into tobacco smoke filters. The resultant filters retain the desirable taste properties and processing capabilities of conventional cellulose acetate filter elements, but are substantially less expensive. Because the core material is non-absorbent, less plasticizer or additive is required for comparable properties, and a web, roving (34) or filter made of such materials has a longer shelf-life. The very fine fibers can be formed of various cross-sections, providing higher surface area and requiring less air in the melt blowing and manufacturing processes. With sheaths of polyvinyl alcohol or ethylene-vinyl alcohol copolymer, the filter element readily disintegrates when subjected to environmental conditions leaving behind only a multiplicity of very fine, substanially unnoticeable, fibers as residue.</p> |
