| 摘要 |
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 x 10-4 to 0.5 micron and which is discontinuous in that it has a porosity within the range of 7,000 to 200,000 cm3/min/10 cm2 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 x 10-4 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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