Method for producing tobacco filters

Abstract

Tobacco filters having uniform hardness and small pressure drop which give uniform flow of smoke can be obtained by forming bundles of fibers consisting of 20-100% by weight of composite fibers based upon the total amount of mixed fibers of said composite fibers and 80-0% of other fibers, subjecting said composite fibers to heat treatment at a temperature lower than the melting point of the first component and higher than the melting point of the second component and stabilizing said fiber bundles by the self adhesion of the second component, said composite fibers having side-by-side or sheath and core arrangement of the first component consisting mainly of crystalline polypropylene or propylene copolymer mainly of propylene and the second component consisting of (1) an ethylene-vinyl acetate copolymer having a vinyl acetate content of 0.5-18 mol % of the total monomers, (2) a saponification product thereof or (3) a mixed polymer of any of the foregoing members (1) and (2) and polyethylene having the total content of vinyl acetate and vinyl alcohol component of 0.5 mol % or more based upon the total monomer content of the mixed polymer; said second component having a circumferential ratio of 60- 100% of the fiber cross-section.