British-american Tobacco Company Limited

James W Phelpstead

Henry G Horsewell

John A Luke

Martin G Duke

In a smoking article comprising a smoking rod and a mouthpiece, the rod may comprise a wrapped body, of particles of tobacco and/or other smoking material, of which body the packing density is in a range of from 100 to 400 mg cm.sup.-3, a passage extending within the rod and in gas-flow communication with the mouthpiece and the article comprising menthol or other vapor-release material at the mouthpiece and/or at a mouthpiece-end zone of the passage. The passage, which may extend substantially to the mouthpiece end of the rod, may be closed at the end thereof remote the mouthpiece end. The passage may be provided by a tube of combustible material or as a bore extending within said body of particles. A portion of the cross-section of the mouthpiece end of the rod not occupied by said passage may be in gas-flow communication with the mouthpiece. The mouthpiece may comprise a filter.

Smoking articles

A tobacco smoke filtration element having a first smoke-flow passage of filtration efficiency less than that of a second smoke-flow passage, the first smoke-flow passage being provided with a heat deformable material which, upon smoking of a smoking article incorporating such a filtration element, deforms and thereby obturates the first smoke-flow passage causing smoke to pass along the second smoke-flow passage and thereby to be subjected to a higher degree of smoke filtration after the first stages of the smoking cycle.

Tobacco smoke filters

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.

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.

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Southampton, United Kingdom

James W Phelpstead