Hot melt adhesive for bonding filter tow, and filter elements bonded thereby

Claim 1

A tobacco smoke filter element comprised of filamentary tow selected from filaments of cellulose acetate, poly(ethylene terephthalate), polypropylene and polyethylene, said filaments being bonded together into a self-supporting filter element having a permeable surface with a hot melt adhesive comprising a blend of about 25 to about 75 weight percent wax and about 75 to about 25 weight percent of a tackifying resin, the blend having a melt viscosity at application temperatures ranging from about 100° C. to about 200° C. of less than about 50 centipoises, wherein said wax is selected from the group consisting of paraffin wax having a melting point from about 55° C. to about 71° C., a microcrystalline wax having a melting point from about 62° C. to about 77° C., and a Fischer-Trospsh hydrocarbon wax having a melting point from about 83° C. to about 103° C., and wherein the tackifying resin is selected from the group consisting of hydrocarbon resins and polyterpene resins having a ring and ball softening point from about 100° C. to about 140° C.