Cigarette with carbon on tow filter

Abstract

A cigarette comprises a tobacco rod and a carbon-on-tow filter comprising a fiber tow with flavored or unflavored carbon particles distributed throughout the tow. The carbon particles have high activity in the range of 90 to 115%, preferably 95%. As mainstream smoke is drawn through the filter, gas phase smoke constituents are removed and flavor is released when the particles are flavored. Ventilation is provided to limit the amount of tobacco being combusted during each puff and such ventilation is arranged at a location near the downstream end of the carbon-on-tow filter to lower mainstream smoke velocity through the filter. The filter achieves significant reductions in gas phase constituents of mainstream smoke, including 90% reductions or greater in at least one of 1, 3 butadiene, acrolein, isoprene, propionaldehyde, acrylonitrile, benzene, toluene, and 80% reductions or greater in acetaldehyde over extended shelf life of the cigarettes.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit of U.S. Provisional Application No. 60 / 636,262, filed Dec. 15, 2004.FIELD OF THE INVENTION [0002] The present invention relates to smoking articles such as cigarettes, and in particular, to cigarettes that include filter segments comprising an adsorbent and fibrous filter materials arranged for advantageous removal of gas phase components from mainstream smoke over extended cigarette shelf life. BACKGROUND OF THE INVENTION [0003] Smoking articles, particularly cigarettes, generally comprise a tobacco rod of shredded tobacco (usually, in cut filler form) surrounded by a paper wrapper, and a cylindrical filter aligned in an end-to-end relationship with the tobacco rod. Typically, the filter includes a plug of cellulose acetate tow attached to the tobacco rod by tipping paper. Ventilation of mainstream smoke is achieved with a row or rows of perforations about a location along the filter. Such vent...

AI Technical Summary

Benefits of technology

[0012] In accordance with the present invention, a smoking article such as a cigarette comprises a tobacco rod and a multi-component filter comprising a fiber tow with particles of highly activated carbon on the tow. In a preferred embodiment, the activated carbon is also flavor-bearing and comprises highly, activated carbon particles on a fibrous tow. As mainstream smoke is drawn through the upstream portion of the filter, gas phase smoke constituents are removed and flavor is released from the activated carbon. Ventilation is provided to limit the amount of tobacco being combusted during each puff and such ventilation is arranged at a downstream location of most of the carbon on tow in order to lower mainstream smoke velocity through the adsorbent. It is believed that highly activated carbon particles on a cellulose acetate tow achieve significant reductions in gas phase constituents of mainstream smoke, including 90% reductions or greater in 1, 3 butadiene, acrolein, isoprene, propionaldehyde, acrylonitrile, benzene, toluene, and 80% reductions or greater in acetaldehyde.

[0013] Advantageously, the present invention addresses the desirability of achieving optimum residence times for the smoke in the region of the filter bearing the adsorbent material while also achieving favorable dilution of the smoke with ambient air and inducing an acceptable resistance to draw as is expected by most smokers.

Problems solved by technology

Such placement, however, tended to lower the filtration effectiveness of the adsorbent, because it tended to increase the velocity of the mainstream smoke in at least a portion of the absorbent bed.

In particular, activated carbon has the propensity to reduce the levels of certain gas phase components present in the mainstream smoke, resulting in a change in the organoleptic properties of that smoke.

Despite these advantages of carbon bearing filters, heretofore they have not been widely employed.

In prior arrangements it has been found that mainstream smoke from carbon filters tends to have a flavor note that is contrary to consumer preferences, and that therefore their employment in commercially offered cigarettes has not been heretofore widespread.

Also, plasticizers in fiber tow filters tend to degrade certain carbon components over time and thereby reduce the efficacy of the carbon in removing gas phase component over extended shelf life of cigarettes that include such filter arrangements.

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