Selective Filtration of Cigarette Smoke using Chitosan Derivatives

Abstract

A smoking article filter having a porous resin with a high surface area to mass ratio comprised of a chitosan derivative. Preferred embodiments include chitosan cross-linked with glutaraldehyde and chitosan cross-linked with glyoxal. The chitosan derivative provides for the selective filtration of cigarette smoke, particularly for the removal of aldehydes, hydrogen cyanide, heavy metals and carbonyls.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This patent application is a divisional patent application of and claims priority to and benefit from, currently pending, U.S. patent application Ser. No. 10 / 842,165, filed on May 10, 2004.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable. FIELD OF INVENTION [0002] This invention concerns improvements relating to tobacco smoke filters. More particularly, the invention relates to a cigarette filter that can selectively remove undesirable constituents from tobacco smoke. BACKGROUND OF THE INVENTION [0003] A wide variety of materials have been suggested in the prior art as filters for tobacco smoke. Examples of such filter materials include cotton, paper, cellulose acetate, and certain synthetics. Many of these filter materials, however, are only effective in the removal of particulates, tars and condensable components from tobacco smoke. The art is replete with a myriad of filtration techniques and materials f...

AI Technical Summary

Benefits of technology

The present invention provides a new and improved cigarette filter that can effectively remove harmful substances from tobacco smoke. The filter uses a porous resin made from cross-linked chitosan, which has been found to have superior performance as a cigarette filter compared to previous methods. The cross-linked chitosan resin has a reduced number of reactive amino groups, which makes it more selective in removing certain smoke constituents such as hydrogen cyanide and formaldehyde. The resin can be incorporated into various parts of the cigarette filter, including the filter sections, the tipping paper, and the shaped paper insert. The technical effect of this invention is to provide a better and safer cigarette filter that can effectively remove harmful substances from tobacco smoke.

Problems solved by technology

Many of these filter materials, however, are only effective in the removal of particulates, tars and condensable components from tobacco smoke.

Among the problems encountered with prior filters has been the plugging or clogging with use and the consumption or rendering ineffective of reactive filtering surfaces and materials.

However, they have little or no effect in removing certain gaseous components in the vapor phase of the tobacco smoke such as hydrogen cyanide, aldehydes, carbonyls, metals and sulphides.

Ion-exchange resins of porous structure have been found to be somewhat effective, but their efficiency diminishes during smoking, as does that of carbon and porous minerals.

This may be due to the material becoming saturated and, therefore, increasingly inactive or it may be due to the release of adsorbed material by thermal desorption of retained substances.

Resins which contain major proportions of tertiary amino or quaternary ammonium groups have been found not to be suitable for removing aldehydes from tobacco smoke.

Among the problems encountered with these materials is that they do not provide a filtration media allowing for the continuous flow of smoke at a low pressure differential or gradient.

Other problems with selective filtration medias have been found.

However, it has been discovered that while glycine can reduce the level of formaldehyde in tobacco smoke, it is not stable in the cigarette filter manufacturing process.

Moreover, the use of amino acids causes the release of ammonia odor during storage.