CIGARETTE WITH DECREASED SIDESTREAM SMOKE

Abstract: Significant decreases in sidestream smoke production, approximately 30 to 70 %, are obtained when compared to a tobacco filler rod wrapped in a conventional cigarette paper by double-wrapping the filler rod, first with a relatively non-porous paper having a Coresta porosity of about 1 to about 10 % and then with a conventional cigarette paper.

Description: TITLE OF INVENTION CIGARETTE WITH DECREASED SIDESTREAM SMOKE FIELD OF INVENTION The present invention relates to a novel cigarette structure which enables a decreased sidestream smoke to be achieved. BACKGROUND ART Cigarettes conventionally comprise a paper tube or wrapper housing a tobacco filler rod and a filter for removing smoke constituents. One of the common problems associated with cigarettes is the amount of sidestream smoke that is formed on static burning, for example, when the cigarette is idling and not being drawn upon by the smoker or is simply resting in an ashtray while burning. Visible sidestream smoke that is formed during static burning is comprised mainly of particulate matter and the smoke often is irritating and objectionable to non-smokers in the vicinity of the idling cigarette. SUMMARY OF INVENTION In accordance with the present invention, there is provided a novel cigarette structure which results in a decreased sidestream emission. In the invention, the tobacco rod is wrapped with two different paper wrappers. There have been a number of prior suggestions to provide cigarettes with two or more wrappers, including the following United States patents: U.S. 3,633,589 Kahane 3,395,714 Kahane 3,744,496 McCarty et al 4,231,377 Cline et al 4,505,282 Cogbill et al 4,585,016 Grollimund 4,624,268 Baker et al In one such patent, U.S. Patent No. 3,633,589 employs in outer porous conventional cigarette paper and an inner sheet which is practically impervious to the passage of air therethrough. Such materials tend to resul-t in a cigarette which is self-extinguishing. By employing an inner sheet having a limited porosity, in accordance with the invention, an improved cigarette is achieved, since a significant decrease in sidestream smoke production is achieved without tending to self- extinguish. It will be apparent from the discussion below of the characteristics of the inner wrapper employed herein that the wrapper material differs from that described in the prior art. The characteristics defined herein are reguired " for the provision of the cigarette with low sidestream smoke. DESCRIPTION OF INVENTION. PREFERRED EMBODIMENT AND BEST MODE The inner wrapper in the present invention is formed of a particular type of paper which is relatively non-porous but has some porosity and contains very little filler. This paper is guite slow burning and tends to produce a significant decrease in sidestream smoke. However, on its own, this wrapper tends to prod ue an unsightly black ash and has a tendency to extinguish the cigarette, both of which are undesirable. It has surprisingly been found that, if the special paper wrapper is wrapped again with an outer wrapper of conventional cigarette paper, then the significant decrease in sidestream smoke is retained, while the black ash color is not visible and there is a decreased tendency for the cigarette to go out. In addition, the cigarette exhibits a decreased tendency to ignite combustible materials. The present invention, therefore, employs a double wrapping of the tobacco rod in the finished cigarette, namely an inner wrapping of a special paper and an outer wrapping of a conventional cigarette paper. The special paper possesses certain properties as noted above. The paper is relatively non-porous but has some porosity, possessing a Coresta porosity of about 1 to about 10 units, preferably about 1 to about 5 units (Coresta porosity is described in the international standard I.S.O. 2965). The low but positive porosity is critical to obtaining a significant decrease in sidestream smoke, in that papers with a porosity of higher than about 5 Coresta units or lower than about 1 Coresta unit are not nearly as effective. In addition, below 2, the cigarette becomes self-extinguishing. The special paper also has a low filler content, generally about 1 to about 8 wt.%, preferably less than about 5%. The paper may have a paper weight which is typically about 18 g/sq.m. In addition to these properties, the inner wrapper may have other characteristics. One component which may be present are salts of organic chemicals, such as citric acid or its salts, to modify the burning rate of the inner wrapper. Such materials, when present, may comprise about 0.1 to about 2 wt%. The inner wrapper may be provided with perforations to permit the passage of gases through them, with such perforations being made mechanically, electrostatically or by laser beam. The decrease in sidestream smoke which is observed is a significant decrease, generally approximately 30% to 70%, over the sidestream produced by smoking a conventionally-wrapped cigarette of the same tobacco blend. The outer wrapper is provided by conventional cigarette paper. Such conventional paper preferably has a weight of about 35 to about 65 g/sg.m. and a filler content,, of about 18 to about 40 wt%. Both rate improvement additives, such as citric acid or its salts, also may be present in an amount of about 0.2 to about 4 wt%. The cigarettes according to the present invention are produced in any convenient manner, generally on a conventional cigarette making machine, with the two wrappers applied to the tobacco filler rod, seguentially or preferably simultaneously. The two wrappers may be laminated together prior to wrapping the tobacco filler rod, if desired. INDUSTRIAL APPLICABILITY As described above, the present invention provides a novel cigarette structure having a decreased sidestream smoke emission by employing a double-wrapping of the tobacco rod, with an inner wrapper of low porosity paper. Cigarettes are staple items of commerce and, accordingly, the present invention has industrial application. Modifications are possible within the scope ofr his invention.

Claims: CLAIMS 1. A cigarette, comprising a tobacco filler rod wrapped in an inner wrapping of a relatively non-porous paper having a Coresta porosity of about 1 to about 10 units and an outer wrapping of conventional cigarette paper, whereby a cigarette is provided having a decreased tendency to produce sidestream smoke when compared to said tobacco filler rod wrapped only in said conventional cigarette paper. 2. The cigarette of claim 1 wherein said relatively non-porous paper has a Coresta porosity of about 1 to about 5 units. 3. The cigarette of claim 2 wherein said inner wrapping has a filler content of about 1 to about 8 wt%. 4. The cigarette of claim 3 wherein said inner wrapping contains about 0.1 to about 2 wt% of at least one burn-rate modifying chemical. 5. The cigarette of claim 1, 2, 3 or 4 wherein said outer wrapper has a weight of about 35 to about 65 g/sq.m. and a filler content of about 18 to about 40 wt% and, optionally, at least one burn-rate modifying chemical in an amount of about 0.2 to about 4 wt%. 6. The cigarette of claim 1, 2, 3 or 4 wherein said inner wrapper and said outer wrapper are simultaneously applied to the filler rod to form a wrapped filler rod from which the cigarette is formed.

Inventors: BOWEN LARRY, COHEN NORMAN, BOWEN, LARRY, COHEN, NORMAN
Applicants: ROTHMANS BENSON & HEDGES, ROTHMANS, BENSON & HEDGES INC.
Application year: 1990
Main classification: A24D1
IPC codes: A24D1