Abstract: A smoking article mouthpiece element comprises a first portion within which a smoke-passage and a ventilation-duct extends from end-to-end of the portion, a downstream end of the duct being spaced from the periphery of the first portion and the wall and the walls of the duct being gas impervious and a second portion disposed at the end of the first portion being in smoke-flow communication with the smoke passage of the first portion, and gas-impervious wall at the end of said second portion closer to the first portion extending inwardly from a first location at the periphery of the element to a second location at the side of the upstream end of the duct further from the first location, the wall bounding a cavity in communication with the duct and segregated from the interior of the second portion. The first and second portions may form respective parts of an integral unit or may be discrete components disposed in end-to-end abutment. The aforesaid wall is suitably part of the second portion.

Abstract: Cigarette filters comprises a filter element, open for smoke flow at the mouth end, and smoke passage of flow impedance less than that of the filter element. The passage is closed at the downstream end so that smoke is constrained to pass into the element at the downstream end of the passage. The passage may be an annular cross-section duct or grooves at the periphery of the element or may be a bore within the element. The filters provide an increasing degree of filtration as smoking proceeds.

Abstract: A mouthpiece element for a cigarette comprises a duct which extends from the periphery of the element at a first location, spaced from the mouth end of the element, to the mouth end of the element at a second location, spaced from the periphery of the element. The element is attached to a cigarette rod by tipping which permits the ingress of air to the duct at the first location. Preferably, during smoking the ratio of the velocity of air issuing from the duct at the second location to the velocity of smoke issuing from the mouth end of the element is in excess of at least ten.

Abstract: A smoking article mouthpiece comprises a smoke passage and a ventilation air duct, both of which extend from end-to-end of the mouthpiece. The duct is of a depth of 25% or more of the diameter of the mouthpiece. When the mouthpiece is incorporated in a smoking article such that air may enter the duct, the ratio of the velocities of air and smoke is in excess of ten. The mouthpiece may also comprise a ventilation-air collection groove which extends about the element and opens into the ventilation air duct.

Abstract: A smoking article comprises a smoking material rod and, to one end thereof, a flow-impedance device comprising a rod-like element of foam or fibrous material which is or has been rendered impervious to the flow of smoke therethrough and one or more open-ended smoke-flow passages extending from one end to the other of the element, the pressure drop of the passage or passages being in the range from 40 to 200 mm, preferably 50 to 100 mm, water gauge and said device being enclosed in a wrapping permitting inward flow of ambient air into the device, which has air-conducting means whereby air flowing inwardly through the wrapping is conducted to the mouth end of the device, the device being effective to remove not more than 25%, preferably 20%, of the total particulate matter of the smoke. The passage or passages may be formed by a bore or bores in the material or by a capillary tube or tubes.

Abstract: A smoke-filter rod comprises a body of rod form consisting or having as at least major constituent a thermoplastics cellulose acetate or polypropylene smoke-filtration material, preferably of a fibrous or filamentary nature, and wrapped in a plugwrap comprising at least 50%, suitably at least 90%, by weight of fibres or filaments of, respectively, cellulose acetate or polypropylene material of substantially the same chemical identity as said major constituent of the filtration material, said plugwrap being bonded to said body and having a permeability for air of not less than 10,000 Coresta units. The bonding is by an agent which is a bonding agent for the material of said plugwrap and said filtration material, suitably triacetin in the case of cellulose acetate. Portions of such filter rod can be subjected to a hot-shaping process.

Abstract: A rod-form body of smoke filtration material, preferably fibrous or filamentary, is wrapped in a fibrous or filamentary plugwrap comprising at least 50% by weight of fibres or filaments of thermoplastics material. The plugwrap may have premeability for air of not less than 10,000 Coresta units. The majority, suitably at least 80% by weight, of the material of the rod-form body is a material other than the said themoplastics material of the plugwrap. Thus the smoke-filtration material may comprise crimped polypropylene tow and the plugwrap be composed substantially wholly of fibrous cellulose acetate or conversely. Portions of such filter rod may be subjected to a hot-shaping process to provide grooved filter elements.

Abstract: A tobacco-smoke filter comprises in admixture or close dispersion a first component which is a ready but weak or weakly retentive adsorbent for vapor-phase constituents, including aldehydes, of tobacco smoke, and a second component comprising amino groups, of which at least 30% are preferably primary groups, and being capable of chemically combining with said constituents to give substantially non-volatile reaction products. Suitably the first component may comprise a porous mineral earth, such as magnesium silicate or silica gel in porous granular form. The second component may comprise an ion-exchange resin or polyethylene imine. The second component may be carried upon a porous particulate material or carried or grafted upon a fibrous material or dispersed in a fibrous material carrying the second material in a dispersed condition. Alternatively, a mixture of granular first and second components may be dispersed in a fibrous or filamentary material or disposed between plugs of such material.

Abstract: A tobacco-smoke filter comprises a plug of filter material of which a transverse cross section is impervious to the passage of smoke except for a minor proportion of the area of that cross section which forms a smoke-accelerating orifice, the plug being enclosed by an envelope permitting ingress of air into a region of the plug downstream of the orifice. The cross section may be impervious because of the presence of a barrier diaphragm of impervious material. Thus an annular groove may be provided in the plug at the cross section and may be filled with, or have its walls coated with, an impervious material. Alternatively the cross section may be impervious by reason of the closure of interstices in the filter material by the local application of heat thereto.

Abstract: A tobacco-smoke filter has a filter body comprising at least one intermediate section which is located between end sections, has a cross section less than that of the end sections and lies wholly within the outline of the latter sections as viewed axially of the body, and a porous wrap of sheet material which is pervious to volatile constituents of tobacco smoke and which bounds, with the said body, at least one space affording a path through which smoke can pass when the filter is in use and from which said constituents are removed fom the smoke by diffusion through the said sheet material, each of the said sections being made of filter material. Suitably the body is of generally cylindrical form and composed of cellulose acetate. Advantageously the intermediate section is integral with at least one end section.

Abstract: The invention is concerned with a wrapped cigarette and a method of producing the wrapper. A very highly porous wrapping paper, with an air porosity within the range from 2,450 to 20,000cm.sup.3 min.sup.-1 10cm.sup.-2 10cmWG.sup.-1 is produced by perforation from a base paper having a tensile breaking strength of not less than 85 g per mm width of paper. The means number of perforations is suitably within the range from 10 to 150 per cm.sup.2 of the paper and the mean diameter within the range from 30 to 200 microns. A cigarette wrapped in the highly porous paper may advantageously be provided with a tobacco-smoke filter having a filtration efficiency for nicotine within the range of 15 to 30%.