British-american Tobacco Company Limited

Richard R Baker

Colin Campbell Greig

Frederick J Dashley

Anthony D McCormack

Donald B Naylor

Federick J Dashley

Barry G Bunn

Smoking articles comprise a smoking material rod wrapped with a paper wrapper including aluminum hydroxide and an organic acid salt of a group I or II metal. The article exhibits at least 30% reductions in visible sidestream smoke when lit.

Smoking articles

A smoking article such as a cigarette comprising a smoking-material rod enwrapped in a wrapper paper with an inherent air permeability of 3 to 45 Coresta units and comprising at least one hydroxide compound and at least one organic compound of the group comprising lithium hydroxide, aluminum hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate, at a total loading level of the compounds of not less than two g/m.sup.2 whereby the total particulate matter (TPM) in the side-stream-smoke emanating from the lit end of said article during the smoking thereof is reduced by at least 30% in relation to the TPM which emanates from the lit end of an otherwise identical smoking article comprising conventional wrapper paper and smoked under the same smoking conditions.

A smoking article such as a cigarette has a rod of smoking material wrapped in a wrapper of which the substantially uniform air permeability due to viscous flow is not more than 3 and preferably not more than 2 Coresta Units and of which the Do/t value is in the range of 0.08 to 0.65 cm sec.sup.-1, preferably 0.15 to 0.25 cm sec.sup.-1. The length of the rod of smoking material may suitably be within a range of 25 to 55 mm. A reduction in sidestream TPM delivery of 40% or more can be obtained. The invention is also concerned with a smoking-article wrapper material which satisfies the above permeability and Do/t value requirements.

A smoking article comprises a rod of smoking material, wrapped in a wrapper, in which rod the packing density of the smoking material varies continuously along at least a major portion of the overall length of the rod, but is constant across any section, within said portion, in a plane perpendicular to the longitudinal axis. The smoking material may be of homogeneous constitution throughout the rod. Preferably the density decreases continuously along the said portion of the rod in the direction away from the end of the rod to be lit, from which end the said portion may extend to substantially the other end of the rod. There may be between a 5% and a 40% weight difference between the more dense half of the length of the rod and the less dense half thereof. The density at the less dense end of the rod may be in the range of 170 to 240 mg cm.sup.-3 and that at the denser end in the range of 290 to 350 mg cm.sup.-3.

An instrument for measuring the air permeability of cigarette paper, including a paper-clamping head arranged to expose a fixed area of paper to a flow of pressurized air from an air pump. A manometer is arranged to measure the pressure differential across the paper and the gas flow is controllable by a control valve to enable a predetermined pressure differential to be maintained. The flow rate through the paper is measured by one of three flowmeters arranged in three parallel gas supply passages for measuring the flow rate in a low medium and high flow rate range respectively. The paper clamping head is such that the flow impedance downstream of the tapping point of the pressure transducer is negligible.

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Southampton, United Kingdom

Richard R Baker