GB764470A - Improved filter for tobacco-smoking devices - Google Patents

Abstract

764,470. Tobacco smoke filters. AMERICAN TOBACCO CO. Jan. 31, 1955 [May 11, 1954], No. 2821/55. Class 130 A cigarette has a filter plug comprising a wrapper 6, Fig. 2, enclosing a plurality of layers of crumpled fibrous material 16, e.g. paper, having particles of activated carbon, e.g. activated charcoal, intermixed with the fibres of the material. The layers may be formed from a single sheet but as shown plugs are cut from continuous rods formed of a plurality of superposed separate layers of transversely creped or other paper forming a ribbon 4, Fig. 1, which is crumpled, and wrapped in a continuous web 6 of paper, in a forming core 9, the resultant rod passing a wrapper-edge pasting roller 13, edge-folder cone 14 and heated sealing roller 15 and being sub-divided by a knife 17. The crepe paper is preferably formed from high-alpha cellulose pulp containing from 2.5 per cent to 60 per cent by weight of granulated active charcoal. Pre-crumbling of the ribbon 4 may be effected by passing it through embossing rollers and/or dies. In Fig. 5 (not shown) a wide ribbon is slit into longitudinal strips by rotary knives and passes between two pairs of embossing rolls having respective upper and lower positive rolls of coarse sandpaper co-acting with sponge rubber negative rolls, the strips then passing through individual successively decreasing circular, square or oval orfices in three die plates before being re-combined in the forming cone. In Fig. 3 (not shown) three strips from separate supply spools pass directly through such die plates to the forming cone. The paper used preferably weighs between about 7 and 30 grams per square metre before creping and crumpling and the granulation of the charcoal is preferably such that substantially all of it will pass a screen having about 100 meshes a square inch and substantially none of it will pass a screen having about 300 meshes a square inch.