US 3720214 A
Description (OCR text may contain errors)
United States Patent 3,720,214 SMOKING COMPOSITION Vello Norman, Chapel Hill, and Herman G. Bryant, In, and Thomas Blair Williams, Durham, N.C., assignors to Liggett & Myers Incorporated, New York, NY. Filed Dec. 3, 1970, Ser. No. 94,949 Int. Cl. A24h 13/00, 15/02 U.S. Cl. 131-17 11 Claims ABSTRAT OF THE DISCLOSURE A smoking composition comprising tobacco and a catalytic agent for causing a decrease in the yield of polycyclic aromatic compounds arising from pyrolytic reactions of the composition, the agent consisting essentially of finely divided zinc oxide and being associated with the tobacco in the composition.
This invention relates to a smoking composition containing tobacco and having a catalytic agent associated with the tobacco. More particularly, it relates to such compositions wherein the catalytic agent associated with the tobacco is finely divided zinc oxide.
Observations of the mechanism of combustion in to-.
bacco compositions such as cigarettes, indicate that the smoke components responsible for biological activity are formed in the pyrolysis zone of the cigarette cone. This has led to a substantial amount of research aimed at reducing the proportion of these components in the smoke which is inhaled by a smoker. It had been proposed that zeolite materials be used to control or influence free radical formation in the pyrolysis zone and thereby cause alterations in the structure of the pyrolysis products formed in expectation of a reduction in their biological activity. An alternative suggested mechanism involves the participation of ionic species in the reformation process of smoke components. For example, US. Pat. 3,292,636 disclosed tobacco preparations in combination with crystalline zeolite molecular sieves such as the L, X, Y or synthetic mordenite types, or naturally occurring faujasite materials, which sieves may contain auy elemental metal having a vapor pressure below 1 atmosphere at 1,000 C. and possessing catalytic activity for organic conversion. In copending application S.N. 749,324 filed Aug. 1, 1968, there is disclosed a smoking composition comprising tobacco in association with a Y zeolite which is at least partially exchanged with zinc ions and may also contain catalytically active palladium metal within or on the alumino-silicate network. Such materials are disclosed to result in tobacco composition wherein vaporized and at least partially oxidized, but unidentified irritant materials, are rendered less irritable to the smoker while the tobacco composition is being consumed. Also, the polycyclic aromatic hydrocarbon content arising from the pyrolytic reaction of these compositions have been found to be reduced by the catalytic activity of the Y zeolite described in the copending application.
It has now been found that a significant decrease in the polycyclic aromatic hydrocarbon content of the pyrolysis reaction produtcs of tobacco-containing smoking compositions can be achieved by admixture of catalytic quantities of zinc oxide with the tobacco. Tests performed with cigarettes indicate that zinc oxide, when combined in cata- Tice lytic association with tobacco results in the polycyclic aromatic hydrocarbon content of the cigarette smoke being reduced by at least about 25% over that of control cigarettes in which zinc oxide has not been associated with the tobacco thereof. In the present invention, the use of zinc oxide provides a common and inexpensive material which is highly effective for the purpose of achieving a significant lowering of the polycyclic aromatic content in the pyrolysis reaction products of tobacco-containing compositions as measured in the smoke produced when such a preparation is burned in air. The present invention comprises application of this surprising discovery to cigarettes, cigars, tobacco and other smoking tobacco compositions.
Accordingly, it is an object of this invention to provide a smoking tobacco composition which on burning substantially reduces the level of polycyclic aromatic compounds in smoke.
Other objects will be apparent from the disclosure and appended claims.
According to this invention, a novel smoking composition is provided which comprises tobacco, and a catalytic agent for decreasing the yield of polycyclic aromatic compounds arising from pyrolytic reactions of the composition, said agent consisting essentially of finely divided zinc oxide and being associated with said tobacco in the com position.
The zinc oxide which has been found to be particularly effective in combination with tobacco to provide the smoking composition of this invention is A.C.S. grade zinc oxide which contains (on a weight basis) less than about 0.005% lead, 0.004% sulfate ion, 0.0025% nitrate ion and 0.001% chloride ion. The particle size of the Zinc oxide is finer than about 50 US. mesh. Generally, the particle size is Within the range of 60-200 U.S. mesh with the greater portion of the material being preferably finer than US. mesh.
The proportion of zinc oxide associated with the tobacco in the smoking composition is in the range of between about 0.1% to 15% by weight of the tobacco used to prepare the smoking composition which may include various additives as hereinafter described. Although the reduced yield of polycyclic compounds arising from pyrolytic reactions of the composition have been achieved at these levels, it has been found that the best results are obtained when the zinc oxide is in the preferred range of from about 0.5% to 8% based upon the weight of the tobacco.
The catalytic agent should be well dispersed throughout the tobacco so that it will be uniformly efi'ective during the entire period during which the composition is smoked. Furthermore, it is important to ensure that the dispersion effectively contacts a maximum volume of smoke which is inhaled by the user. Since the catalytic activity of the zinc oxide is most likely a surface phenomenon, the greatest likelihood of maximum contact between the smoke being drawn in by the user and the zinc oxide is obtained when. the area/volume ratio of the zinc oxide particles is maximized for a given weight of zinc oxide. For this reason, it is employed as a fine powder of particle size preferably smaller than about 100 US. mesh.
One method of application of the zinc oxide to the tobacco is to dry blend the zinc oxide, ground tobacco, a fibrous material and a binder. Dry blending, as in a conventional double cone blender effectively distributes the zinc oxide over the surface of the tobacco, including the pores within the tobacco surface which are large enough to accept the zinc oxide particles.
When required, dry blending is followed by wet mixing with water and casing materials in proportions sufficient to provide the resulting mixture with the appropriate consistency for conventional reconstituted tobacco sheet manufacturing operations. The sheet is then cut into strips and used in cigarette manufacture as such, or it can be blended in any desired proportion with regular tobacco.
The fibrous material which is a constitutent of the dry blend can be, for example, a-cellulose or fibrous tobacco stem material. The binder portion of the dry blend may be sodium carboxymethyl cellulose, or a natural gum such as guar gum. The casing materials used in the wet mixing step are usually glycerin and propylene glycol. Of course, any other known fibrous material, binder or casing materials known to be useful in combination with tobacco products can be used in combination with or in place of those herein set forth.
Alternatively, zinc oxide can be dusted directly onto cut and cased blended tobacco and manufactured into cigarettes or other products in this form.
It is also desirable to incorporate the zinc oxide by commingling it with powdered tobacco and stem or other fibers prior to reforming it into a reconstituted tobacco sheet.
The weight proportions of the additives described above for use in reconstituted tobacco sheets are within the following approximate weight ranges. The proportions shown are within the usual range required to provide useful tobacco products.
Material: Weight percent Fibrous 4-8 Binder 1-20 Casing About 3-9 Comprising:
(a) Glycerin 4-6 (b) Propylene glycol 0.5-2
Tobacco, balance to 100%.
The smoking composition may be further processed and formed into any desired shape or used loosely e.g., cigars, cigarettes, and pipe tobacco in a manner wellknown to those skilled in the tobacco art.
The invention will be more clearly understood from the following typical example which is provided by way of illustration and not limitation and in which the proportions are in parts by weight unless otherwise stated.
EXAMPLE 1 4 lbs. of ZnO was added to a mixture of 140 lbs. of ground strip tobacco blend, 12.4 lbs. of Solka Floc (occellulose) and 6.5 lbs. of sodium carboxymethyl cellulose. This combination was dry-mixed for one hour in a double cone blender and then wet-mixed in a paddle mixer with 1.08 gal. of glycerine, 0.33 gal. of propylene glycol and 8 gals. of water. The resulting damp mixture was processed in conventional reconstituted tobacco making equipment at the rate of 600 lbs/hour. The resulting sheet, at 12% moisture level, was cut at 32 cuts/ inch and fabricated into cigarettes on conventional cigarette making machinery.
Control cigarettes were prepared in like manner except that the zinc oxide, was omitted.
Cigarettes made in accordance with the procedure of Example I were tested and compared with the control cigarettes in order to determine the effect of the zinc oxide on the polycyclic aromatic hydrocarbon content of the smoke. All of the test cigarettes were 85 mm., long and were wrapped in a cigarette paper having a Greiner porosity of 22 seconds. The test results shown in Table I are typical fthe consistent data which have been obtained.
TABLE I Control Sample 17M Cigarette characteristics:
ZnO, percent 2 H2O 12.3 18.1 Weight (grams) 1.696 1.809 Burn rate (mm./mln.). 3. 33 3.46 Polycyclic aromatic hydrocarbon in smoke drawn through the cigarette: Infra-red (arbitrary units) 1 194 87 1 IR spectral absorption in the region of aromatic CH bonding vlbra' tions (11.9-14.0;i).
What is claimed is:
1. A smoking composition comprising:
(a) tobacco; and,
(b) a catalytic agent for causing a decrease in the yield of polycyclic aromatic compounds arising from pyrolytic reactions of said composition, said agent consisting essentially of finely divided zinc oxide particles and being associated with said tobacco in said composition, the weight proportion of the zinc oxide being between about 0.1% and 15% by weight of the tobacco.
2. The composition of claim 1 wherein the particle size of said zinc oxide associated with said tobacco is less than about U.S. mesh.
3. The composition of claim 2 wherein the weight proportion of said zinc oxide is between about 0.5% and 8% by weight of said tobacco.
4. The composition of claim 1 wherein said composition is in a cigarette.
5. The composition of claim 1 wherein said compo-sition is in a cigar.
6. The composition of claim 1 wherein said composition is in pipe tobacco.
7. A cigarette comprising:
(a) tobacco; and
(b) a catalytic agent for causing a decrease in the yield of polycyclic aromatic compounds drawn through said cigarette which arise from pyrolytic reactions in said cigarette, said agent consisting essentially of finely divided zinc oxide particles catalytically associated with said tobacco, wherein the weight proportion of said zinc oxide associated with said tobacco is between about 0.1% and 15% by weight of said tobacco and the particle size of said zinc oxide is less than about 100 US. mesh.
8. In the process of making tobacco containing smoking preparations, the step of admixing catalytic quantities of a catalytic agent consisting essentialy of finely divided zinc oxide particles wherein the weight proportion of the zinc oxide admixed with the tobacco is between about 0.1% and 15% by weight of the tobacco.
9. The method of claim 8 wherein the weight proportion of said zinc oxide admixed with said tobacco is between about 0.5 and 8% by weight of said tobacco.
10. The method of claim 8 wherein the particle size of said zinc oxide admixed with said tobacco is less than about 100 US. mesh.
11. The method of claim 9 wherein the particle size of said zinc oxide admixed with said tobacco is less than about 100 US. mesh.
(References on following page) 5 6 References Cited Beitrage zur Tabaksorsbhung Band 4, Heft 7 December 1968 (3046), Translation, pp. 269-474. UNITED STATES PATENTS The Chemistry and Technology of Tobacco (text) by 2,429557 10/1947 Sowa 131-140 B A. A. Shmuk, published by Pishchepromizdat, Moscow 3 4 12/1966 y 1- R 5 1953. Translation by The National Science Foundation 3,251,365 5/1966 Keleth H et 131-10.? Washington, 110., 1961, pp. 498 and 499 esp. cited.
OTHER REFERENCES MELVIN D. REIN, Primary Examiner The Effect of Additives on the Combustion Tempera- U S C XR tures of Cigarettes, (pub.) by F. Miller, W. J. Freeman 10 and R. L. Stedman. 131-9