Brown & Williamson Tobacco Corporation

British-american Tobacco Company Limited

Robin Arthur Crellin

Henry G Horsewell

James William Phelpstead

Christopher Robert Jenkins

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%.

Cigarettes

According to the invention, a material for the filtration of tobacco smoke by reduction of vapor-phase constituents without adverse effect on the taste of the smoke comprises carbon particles of a size substantially within the range of 300 to 1700 micron, coated over their surfaces, individually and without being bonded together, with a barrier layer which has a thickness within the range of 5 .times. 10.sup.-4 to 0.5 micron and which is discontinuous in that it has a porosity within the range of 7,000 to 200,000 cm.sup.3 /min/10 cm.sup.2 per 10 cm water gauge and a permeability for organic vapors contained in tobacco smoke such that it permits the passage of molecules within the size range 5 .times. 10.sup.-4 to 2 micron, the said layer being composed substantially of an organic non-nitrogen-containing polymeric material which is non-volatile, substantially non-water-soluble and non-toxic. The invention is further concerned with tobacco smoke filters comprising such coated carbon particles.

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Romsey, United Kingdom

Robin Arthur Crellin