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Cigarette filter incorporating nanofibers

Cigarette filter incorporating nanofibers description/claims

This application is a continuation of U.S. application Ser. No. 10/896,762 filed Jul. 21, 2004, which claims the benefit of U.S. provisional patent application Ser. No. 60,481,111, filed Jul. 21, 2003.

The present invention relates to filters, and in particular to cigarette filters.

Cigarettes are frequently provided with filters to remove some of the contaminants, or hazardous components, of cigarette smoke before the smoke is inhaled. Such hazardous components include tar, carbon monoxide and various carcinogens. Various cigarette filters are known in the prior art which decrease the toxic effect of tobacco smoke. These consist of a base made of acetate, cellulose or acetate-cellulose fibers with substances applied to the base which have adsorption properties or are impregnated with these substances. Activated charcoal, inorganic and organic slats of various acids are used as the adsorbing agents.

In one known form of construction, the filter body consists of a tow of continuous filaments, commonly cellulose acetate (acetate) filaments, arranged parallel to the longitudinal axis of the cigarette. In another known form of construction, the filter body consists of pleated or fluted paper compressed into a cylinder. The paper is subjected to a grooving process to allow it to be so pleated or fluted. Such forms of construction contain a single filter element and may be called “mono” filters. Another known form of construction is the so-called “dual” filter which contains two filter elements, namely a paper filter towards the interior and a tow filter towards the exterior of the cigarette. A further known form of construction is the so-called “triple” filter, which contains three elements, namely a paper filter and a tow filter, as in the “dual” construction, separated by an air gap or by an activated carbon filter. Paper filters are known to be generally more efficient at removing tar from tobacco smoke than are tow filters. High tar removable efficiency is particularly desirable in view of the trend towards low-tar cigarettes.

A drawback of these filters is that the range of substances absorbed by them is restricted. The filters themselves can degrade on heating, which is accompanied by the formation of toxic compounds.

Also, in the prior art, there exists filtered cigarettes that fall into the category of Less Harmful Cigarettes (LHCs) or Reduced Risk Cigarettes (RRCs). But these are chemical based and require extensive testing to prove efficacy. In fact, there continues to be debate about the efficacy of LHCs and RRCs.

It would be desirable to provide a cigarette filter element which is capable of removing certain gas phase components of mainstream cigarette smoke, while not adversely affecting the flavor.

It is an object of the present invention to provide a cigarette filter that removes contaminants or hazardous byproducts of cigarette smoke, such as tar and carbon monoxide, from cigarette smoke.

It is another object of the present invention to provide a cigarette filter that filters out hazardous components of cigarette smoke by mechanical means.

The present invention provides a cigarette that comprises a tobacco rod and a filter coupled to the tobacco rod. The filter comprises a tow made of nanofibers.

In accordance with one aspect of the present invention, the pressure drop across the filter is between 50-150 millimeters wg.

In accordance with another aspect of the present invention, the weight of the filter is between 50-400 g/1000 rods.

In accordance with another aspect of the present invention, the filter tow is comprised of cellulose acetate.

In accordance with another aspect of the present invention, the filter comprises activated charcoal.