| 摘要 |
A tobacco smoke filter for cigars or cigarettes is porous and coheres and has a filter mass containing cellulose fibres and formed by drying of a wet strand, the fibre disposition being such that no uninterrupted longitudinal channels exist in the filter, and the formed fibre mass having a density not greater than 0,18 gm. per c.c. whilst the porosity of the filter is such that one 11 mm. long and 8 mm. in diameter would not offer more than 50 mm. water column resistance to a lengthwise air flow therethrough of 700 c.c. per minute. Preferably, wood-wool fibres are used. Magnesium, lime, silicates, or silicones in pulverised, laminated, shred and/or fibre form may be added to loosen the fibre structure, or the fibres may be initially treated with solutions of these substances e.g. water-glass. Fibres of cotton, wool or artificial silk, or paper shreds, may also be added, as may pulverised carbon or synthetic resin particles such as strips of crushed synthetic resin foam. The basic fibres should preferably form at least 30 per cent, and normally form all but a few per cent, of the filter, the surface of which may be rendered smooth or slippery as by being treated with glue, gelatine, starch, wax, synthetic resins or other thermoplastics, e.g. polyethylene may be applied in powder form and subsequently heated and calendered: the filter may be pre-heated. An adhesive paper strip may be moistened or heated and drawn, together with the filter strand, through a heated nozzle. The filter mass may be formed by casting, as in Specification 748,095; by a continuous-rod method using a paper or glue covering; or by dispersing moist fibres in an air stream and imparting a cylindrical shape to the fibres in a channel with or without an added binder. Specification 433,048 also is referred to. |
