Tobacco-smoke filters

Claim 1

A cigarette filter for tobacco smoke comprising a porous tube of thin-walled filter paper and an external supporting one piece tubular case of plastics material, within which the tube extends longitudinally, the case being formed with longitudinal internal ribs extending over substantially its whole length by which the tube is directly contacted and supported throughout its length in substantially annular spaced relation with respect to the case, spaces within the tube and between it and the case having closures at opposite ends, the closure at one end being an annular seal between the rim of the case and the rim of the tube which is constituted by an inturned lip formed from the plastics material of the case and fused to the tube, whereby smoke is prevented from passing between the case and tube at one end, and the closure at the other end being in the form of a plug mounted in the other end of the tube to prevent smoke from passing through the outer end of the tube so that smoke entering the filter at one end is constrained to pass substantially radially through the filter-paper tube before reaching the other, outlet, end.