Patent GB-741429-A (GB)
Title: Improvements in or relating to tobacco smoke filters
IPC: A24D3/02
Filed: 1953-02-13
Abstract: 741,429. Tobacco smoke filters. GAMBLE, H. Oct. 28, 1953 [Feb. 13, 1953; March 12, 1953], Nos. 4128/53 and 6885/53. Class 130. Filters each comprise an element 4, Fig. 2, acting mainly by other than mechanical filtration, such as silica gel crystals or chemically impregnated wool or cotton-wool, confined between and by elements 2, 3 acting mainly by mechanical filtration, such as crepe paper and cotton-wool wadding respectively, the element 4 being in and in contact with a tube which may be a cardboard &c. mouthpiece insert 5 in a cigarette tube 1 or the mouthpiece end of the tube 1 itself. The filters may also be used in cigars, pipes and cigarette and cigar holders. Making filter elements. Silica gel crystals 4 may be loose or have an envelope which may be formed by longitudinal folding and subsequent lateral sub-division of a strip 61, Fig. 24, along the centre of which the crystals are deposited at random or in groups 58a. Adhesive may be applied along the free side-edges 59 and, where appropriate, between groups 58a at lines 60 of subsequent subdivision. In all cases the strip 61 may be used alone, when it is preferably of soft material such as cotton or cellulose wadding, or in conjunction with a strip 62 which is folded in the opposite direction, the strips being of wadding, cellulose, crepe paper, textiles &c. and not necessarily both the same. In lieu of folding, the strips may be superimposed and joined at their edges, and, if appropriate, between the groups 58a, by sewing or crimping. A single strip having crystals distributed completely over one side may be spirally or otherwise folded to enclose the crystals, and subdivided as before. According to the second Provisional Specification, crystals can be deposited on one half of a strip and the other half folded over it and in this case, or when two strips are used, the completed continuous element may be stored flat in reels and later passed through a former to round it before subdivision. Where an envelope is used open-ended, it is inserted into the tube 5 so that its cut ends contact the wall thereof. The crystals may also be embedded in a porous carrier of plate or rod form from which individual filter elements are stamped out or cut off respectively, the carrier being initially a liquid made porous as by frothing or blowing and partially or wholly solidified with simultaneous or subsequent shaping. Filter assembly. Assemblages 1, 2, 3, 4, 5, as in Fig. 2, or, with appropriate modification, assemblages 2, 3, 4, 5 only, may be made (1) by rotating a horizontal disc to carry verticallydisposed cigarette paper tubes already provided at their lower ends with the elements 2, 5 past stations at which the elements 4, 3 are successively supplied, e.g. loose crystals from a dosing hopper and a wad by a rammer, and (2) by intermittent rotation of a fluted drum 32, Fig. 8, past stations at which are successively supplied to each flute (a) an assembly 1, 5, 3, (b) loose crystals 4 from a hopper 10 and retained by cover plates 38 and (c) crepe paper 2 which under the action of a rammer 36 displaces the elements 4, 3 into their ultimate positions in the tube 5, itself temporarily held down by a member 37. Assemblages 2, 3, 4, Fig. 2, may be made and inserted into a tube 1 or 5 by supplying to holes 9, Fig. 4, of an intermittently rotated disc 7 first wads (or crepe paper) and then, whilst the holes are closed at one end by a back plate 19, crystals delivered by a rammer (not shown) from the spout 11 of a hopper 10, a front plate 18 then also covering the holes until they overlap an intermittently rotated disc 6 having holes 8 into which crepe paper (or wads) has been inserted, the contents of the holes 8, 9 being ejected into the tube 1 or 5, Fig. 2, by a rammer (not shown) at a point A where the holes register. The hopper 10 has a wall 10a shaken by a toothed wheel 24 and spring 22a, and the spout 11 has a slide 12 which has an end recess 15 registering as shown with the holes 9 but which may be moved in to cut off the supply of crystals to the holes, a hole 16 in the slide then allowing passage of the appropriate rammer so that the machinery may still operate, to make filters without crystals. The crystals may be replaced by chemically impregnated wool filter elements cut from a strip and dropped individually into position before the holes 9. In Fig. 33 (not shown) double-length filters are produced using a drum having a central holed or fluted section receiving at one station doublelength crepe paper elements, an outer holed or fluted section on each side receiving at a later station single-length wads, and, between the central and outer sections, fluted sections receiving crystals at a station between or after the other stations, the final filter assembly being ejected by a rammer into a cardboard or paper tube.