Patent GB-1121474-A (GB)
Title: Tobacco smoke filters
IPC: B01D39/00
Filed: 1965-09-01
Abstract: Compositions for addition to crimped filaments in the manufacture of tobacco smoke filters comprise solid particles capable of increasing filtering properties of the filters and solid particles of a heat-sensitive polyolefin. Specified polyolefins are polyethylene, polypropylene, ethylene/propylene copolymers and propylene/butylene copolymers.  Specified solid materials are activated carbon, e.g. derived from wood, petroleum, coconut shell, coal, blood and bone; and rice starch, cellulose acetate and calcium carbonate.  Examples describe particulate compositions of carbon and (I) polypropylene, (II and V) polyethylene, and (III) a propylene/butylene copolymer, and of (IV) cellulose acetate flake and polyethylene.ALSO:Tobacco smoke filters made of crimped filaments wherein solid particles of size 12 to 200 mesh capable of increasing the filtering properties of the filter are bonded to the filaments by means of solid particles of size 10 to 300 mesh of a heat sensitive polyolefin, may be prepared by applying to the filaments and heating to the softening temperature of the polyolefin, before or after conversion into filters, a particulate composition of said solid particles and polyolefin containing 50 to 95 weight per cent of said particles.  The filaments may be of cellulose, cellulose acetate, polyolefin polyamide, polyester or polyacrylonitrile.  Specified polyolefins are polyethylene, polypropylene, ethylene/propylene copolymers and ethylene/butylene copolymers.  Specified solids are activated carbon, e.g. from wood, petroleum, cocoanut shell, coal, blood or bone; or rice starch, cellulose acetate or calcium carbonate.  In examples compositions of carbons and (I) polypropylene, (II and V) polyethylene and (III) a propylene/butylene copolymer, and of (IV) cellulose acetate flake and polyethylene are applied to crimped cellulose acetate tows which are made up into filters.ALSO:In a method of making tobacco smoke filters from crimped filaments solid particles of size 12 to 200 mesh capable of increasing the filtering properties of the filters and solid particles of size 10 to 300 mesh of a heat sensitive polyolefin are applied to the filaments which are heated, before or after conversion into filters, to the softening temperature of the polyolefin so that upon cooling the polyolefin particles bond the solid particles to the filaments.  A tow of filaments may be treated to separate and partially deparallelise the individual filaments, to which the solid and polyolefin particles may then be applied, separately or in admixture.  The band of treated filaments may then be caused to assume a cylindrical shape, wrapped and cut to lengths to form cigarette filters, heating to effect bonding being carried out before or after the treated filaments are formed into filters.  In examples crimped cellulose acetate tows are sprinkled with particulate compositions comprising (I) polypropylene and carbon (II and V) polyethylene and carbon, (III) a propylene/butylene copolymer and carbon, and (IV) polyethylene and cellulose acetate flake; and the tows are (I-IV) compacted and wrapped with paper tape to form filter rods which are heated to effect bonding or (V) heated to effect bonding and then compacted and wrapped with paper.