US3005732A - Tobacco composition and smoking unit containing material for eliminating deleterious matter - Google Patents

Description

United States Patent M 3,005,732 TOBACCO COMPOSITION AND SMOKmG UNIT CONTAINING MATERIAL FOR ELIMINATING This invention relates to smoking compositions and to smokable units including therein a novel combination of particulate inorganic additives intimately associated with tobacco, the additives being capable inter se of substantially reducing the quantity of tars normally generated during the burning of the tobacco and improving the aroma of the tobacco. For many reasons, clinical and aesthetic, reduction in the tar yielded during the smoking of tobacco is highly desirable. First, there exists strong clinical, statistical and pathological evidence that certain constituents of tobacco smoke condensate (or tars as such condensate is usually termed) are potentially carcinogenic when deposited on human tissue. These carcinogens have been reported to be mixtures of essentially neutral high-molecular weight polycyclic hydrocarbons, the carcinogenic potency of any mixture depending on the species present. Several general types of polycyclic aromatic hydrocarbons are usually present in tobacco smoke condensate and undoubtedly many individual molecular species are hence present. Deleterious polycyclic hydrocarbons are undoubtedly of pyrogenic origin since they cannot be isolated from raw tobacco prior to the pyrolysis thereof. These noxious substances are ordinarily carried as dispersed droplets or solid particles in the efiiuent smoke stream and thence into the smokers respiratory system along with the aroma and taste producing constituents of the smoke. Secondly, aside from their alleged pathological effect, it appears that certain constituents of tars are responsible for the sharp irritating taste imparted to smoke from a cigarette or the like. Furthermore, tars produce disfiguring coloration of the teeth of many smokers and, if only for this reason, the lowering of total tars yielded during smoking is highly desirable.

Many eiforts have been made in the past to reduce the yield of tars in the effiuent smoke of tobacco. One method involves the commingling with smoke tobacco of particulate solids having high sorptivity by virtue of their large specific surface, internal and external. However, at the high temperature encountered in the combustion zone of tobacco mixtures the sorptivity of materials such as, for example, certain sorptive clays, silica gel, alumina gel and the like, is substantially reduced. The tobacco industry has failed to find that the inclusion of such materials in tobacco compositions is of sufiicient value to warrant their use in commercial smoking mixtures. The use of filter-tips has, on the other hand, met widespread acceptance both by the cigarette industry and the consumer. Filter-tips as well as cigarette holders are not, however, without disadvantage. A primary disadvantage of a filter-tip is that its presence interferes with the ease of draw that is characteristic of a well-made cigarette. Another significant disadvantage of a filter-tip is that its presence encourages the smoker to smoke more completely the cigarette at the butt end than he would smoke the cigarette in the absence of the filter-tip. This is so because the filter-tip provides a fingerhold for a cigarette so that the intense heat of the advancing combustion zone does not force the smoker to extinguish the cigarette when smoked too close to the butt end. It is known that during the course of smoking the sorption of tars towards the cigarette butt by unconsumed 3,005,732 Patented Oct. 24, 1961 tobacco causes relatively heavy deposition of tars proximate the butt end of a cigarette. Hence it is desirable that smoking of a cigarette be ceased prior to the complete pyrolysis of the cigarette.

It is thus apparent that smoking mixtures which include an innoxious additive which is capable of substantially lowering the tar yield of said tobacco when smoked meets a long-felt need of the tobacco smoker. Furthermore, substantial benefits result when such an additive inherently possess the ability to eliminate or reduce substantially the percentage of noxious constituents of the total tar.

The desiderata for an ideal treating agent for eliminating high-molecular weight undesirable components from the etlluent smoke of the tobacco in a cigarette or the like and simultaneously reducing total tars are:

(l) the ability to eliminate substantially these deleterious components without undesirable alteration of the agent itself and without substantial reduction in the quantity of lower-molecular weight, desirable aromatic compounds generated;

(2) residual sorptivity, so that any undestroyed highmolecular weight component will be sorbed and undergo secondary treatment rather than be carried into the effluent smoke;

(3) ability to function at the elevated temperatures encountered at and proximate to the flame-front;

(4) non-toxic;

(5) ability to retain physical structure in the presence of moisture.

Accordingly, it is a principal object of the instant invention to provide a composition including tobacco which incorporates a novel combination of treating agents to reduce substantially the quantity of tars inthe efiluent smoke of said tobacco and simultaneously reduce the concentration of deleterious high-molecular weight constituents in said tar.

Another object ofthe invention is the provision of a composition-including tobacco intimately associated with a novel combination of treating agents which are capable of acting inter se to promite the formation of relatively low molecular weight compounds of pleasant aroma to the exclusion of the formation of higher-molecular weight, potentially. carcinogenic substances.

Another important object of the invention is the provision of smoking units including a novel combination of particulate additives which act synergistically to reduce the quantity of tar generated during smoking of that unit.

It is another object of the inventionto provide smoking units including such'compositions which inherently possess the ability to-improve simultaneously the aroma of the smoke from the tobacco and reduce substantially the quantity of tar generated during smoking of that unit. 7

Other objects will be apparent from an inspection of the following description of the invention.

The instant invention is a result of my discovery that an improved smoking composition is provided by the intimate association with tobacco bf the combination of a comminuted material and a finely-divided innoxious incombustible solid capable of endothermic dehydration at a temperature not to exceed the flame-front temperature of the tobacco mixture when smoked. The term innoxious as used herein refers not'only to the quality of being noninjurious to health but also to the quality of being inofiensive to the senses. Tobacco compositions of my invention are distinguished bytheir ability to burn with substantially reduced production of tar per unit of tobacco. Furthermore, by virtue of the presence of the said comminuted material the composition inherentlypossesses the ability to 'promote the pyrogenic formation of desirable low-molecular weight hydrocarbons to the exclusion of higher-molecular weight deleterious polycyclic aromatic compounds. A copending US. patent application of SerialNo. 692,247, filed October 25,, 1957, by Frank A.

Howarddiscloses. smoking. eompositionsdncluding tobacco I intimately associated with a finely-divided solid, capable. of endothermic dehydration at a temperature not to exceedthe flame-front temperature ofthe tobacco mixture when, smoked. Another copending; US, patent application of Serial No. 699,921, filed November 29,, 1957, by A. J. Mueller relates to tobacco compositions in which a cornminuted material is commingled with smoking tobacco-for the purpose of desirablyaltering the distribution of the combustion products of tobacco by curtailing the formation of the potentially carcinogenic compounds and promoting the formation of lower molecular weight compounds. of pleasing aroma. lhave found that neither genus, i.e. said cornminuted material or endothermically dehydrating solid, has, when used as a sole additive to. tobacco, the outstanding ability to curtail the total tar produced per unit of tobacco that is possessed by species of; the genera in combination. Tobacco compositions at my invention combine in synergistic form and eliect two heretofore suggested tobacco additives to attain unexpectedly outstanding benefits, Smoking, mixtures made inaccordance with the subject invention are characterized by the generation, of a mild-tasting smoke of enhanced aroma. Furthermore, such additives in combination fulfill the desiderata of an ideal agent tor the purposes above set forth.

Although I do not wish in any way to be. bound by the hypothesis, herein set forth, it felt; that endothermic dehydration of an additive at the temperature developed during combustion of the. tobacco mixture operates in dual fashion to improve the smoking characteristics of the tobacco. First, by virtue of the endothermic dehydration of the hydrated additive, combustion takes place at a temperature lower than it would occur in the absence of the endothermic dehydration. Lowering of the combustion temperature of tobacco from the normal 880x30 C. to 800 C. or lower is known to reduce. the pyrogenesis of high-molecular weight noxious, polycyclic. aromatic compounds. Second, when this endothermic dehydration occurs in the intimate. presence of said comminuted material the. steam generated in situ is available to cooperate with. the catalyst to improve, thereby the ability of said material to alter the combustion-controlling characteris tics. of said material.

, Briefly, in accordance with. my invention comminuted material and an innoxious. incombustible; solid capable of endo hermic lly dehydrating at; a mperature no to xceed the flame-trout temp ra ure of; the mixture. when smoked are commingled with each otherrand with, tobacco. e t c o y he form of. she ts, hreds r filaments and, accordingly, smoking mixturesz. ohmy invention, are uiuzful in igar tt pip s of dams.

More specifically, I have discovered that the addition to tobacco of a, combination, of a comminuted material. and

endothermically dehydrating solid in combined amount of from about. 1, to, 20 percent (based, on the weight of the tobacco) and preferably from about, 2,, to percent, same basis, produces outstanding benefits. Howeyenthe optimum ratio of total additive to tobacco. to effect the maximumv tax: reduction consistent with satisfactory ease of draw, a lity Of the, mixture to sustain burning, preservat on of redolence and the like, is best determined. experimentally for a specific, tobacco composition. This is so because the quantity of tars generated during smoking varies considerably, inter alia, with toba co specie and presence of tobacco treating agents (exemplified by humectants, invert siugar, cocoa essential oils, chocolate and licorice). Furthermore, commercial smoking mixtures. usually comprise a plurality of tobacco species. Llsetul r i of. t ys t hydrat d lime vary consider-a bly, ratios of catalyst to endothermically dehydrating solid within the range of from about 1:5 and 5:1 being most suitable. Within the range of about 1:2 and 2:1, however, optimum cooperative effect is usually manifest with respect to total tar reduction when the additives are used with popular smoking mixtures. The optimum ratio will vary somewhat with the temperature at which. said endothermic dehydration takes place and accordingly will vary with specie of endothermically dehydrating additive.

Suitable siliceous materials for the purpose of my inven tion include materials from natural or synthetic sources as exemplified by alumina-silica materials. containing from about 1 to 50 percent alumina by volatile-free weight, volatile-free weight being the weight of the clay after being heated to substantially constant weight at about 1700 F. Alumina-silica materials are variously prepared by methods well-known to those skilled in the art. Such methods include the acid activation of naturally occurring clays. such as. kaolin, halloysite and montmorillonite clays, by corprecipitation of silica and alumina or by impregnation of silica gels. Other materials are prepared by coprecipitation of silica with other refractory oxides such as beryllia and zirconia in the absence or presence of alumina or by impregnation of silica with materials capable of yielding such oxides. However, because of its outstanding resistance to sintering at the elevated temperatures encountered at or proximate to the flame-front of a smoking unit the preferred material is a high-alumina siliceous material prepared by acid activation of kaolin clay. The alumina content of such a material is from m percent by volatile-free weight of the material.

The preparation of the preferred material is described in the copending US. patent application of Serial No. 490,128, filed February 23, 1955, by Alfred J. Robinson et al. In accordance with that invention an acidactivatablc clay, preferably kaolin, is mixed with sulfuric acid to an appearance of homogeneity and the homogeneous mixture is reacted at elevated temperaa ture to bring about substantialreaction between'the acid and alumina of the clay, and without washing out any of the water soluble products of the reaction, calcining the reactant mixture to eliminate substantially the sulfate therefrom. As used herein, the terms kaolin or kaolin clay are those clays which include in the raw state as the principal clay mineral constituent, kaolinite, halloysite, indianite, dickite, nacrite or anauxite. All of these clay minerals are hydrous aluminum silicates prior to calcination and are represented by the formula Al O .2SiO .n'H O, It usually being 2. The ratio of silica to. alumina. is about to, 1.5, and most generally about, 1.18. The alumina content of the acid-activated clays is from about 40 to 50 percent by volatile-free weight, and usually about 46 percent.

l The additives are preferably incorporated in the tobacco of a cigarette in a very finely-divided form, usually less than about 10 microns and preferably having a substantial portion between about 0.5 and 2 microns. In general the more finely-divided the additive the greater the surface available to combat deleterious substances and the greaterthe adhesion of the catalyst to the tobacco particles. Of course it will be understood that the particular particle size used in a tobacco composition will depend on such factors as moisture content, quantity of humectant, size of tobacco particle and quantity of said material and hydrated endothermically dehydrating mater al used. The specific amount will vary principally with the type and quality of tobacco used and the optin-mm amount is best ascertainedby the smoking characteristics of the composition, such as ease of draw, abil-.

ity to sustain burning, analysis, of combustion. products,

taste. and aroma characteristics.

Useful solids which decompose endothermically include innoxious incombustible infusible materials which dehydrate without evolution of noxious products and which do not leave in the ash, foul or offensive materials.

Although the invention will be described with particular reference to compositions in which the endothermically dehydrating solid is a mineral it will be understood that certain particulate hydrated salts and oxides may be used when they possess the requisite capacity to dehydrate endothermically within the select temperature range, are innoxious before and subsequent to dehydration and will not melt during tobacco pyrolysis to thereby interfere with the activity of the said material. The term dehydration as used herein refers to a loss of combined water or water of constitution or chemically bound water from a material. Such bound water is to be distinguished from physically bonded or free moisture which is eliminated at relatively low temperatures.

Although solids which dehydrate endothermically at temperatures as low as about 100 C. may be used in compositions of the invention with some benefit, nevertheless the decomposition of such a material will occur at a distance from the advance of the flame-front and greater dissipation of the heat loss will occur than when the material employed for the purpose undergoes endothermic dehydration at or within about 125 C. of the flame-front temperature. The theoretically ideal solid for the purposes of the instant invention is one which dehydrates at the temperature of the flame-front for the particular tobacco-solid mix. In general, particularly useful are those solids decomposing endothermically from about 500 C. up to about the normal burning temperature of the particular tobacco specie or mixed species in the presence of the added particulate solids.

Suitable minerals endothermically dehydrating within the preferred temperature range, that is from about 500 C. up to burning temperature of the mix, include chlorite (d. about 800 C.), kaolin clay which undergoes an intense endothermic reaction at about 500- 550 C., brucite dehydrating at about 350 C., vermiculite which undergoes a series of dehydrations within the preferred temperature range, diaspore (--A10.0H) and boehrnite (-Al0.0H), both of which are bauxite species and undergo endothermic dehydration at a temperature level similar to that of kaolin. Another useful hydrated alumina is gibbsite, the chief mineral constituent of domestic bauxite, the mineral dehydrating endothermically at 300-350 C. Georgia-Florida fullers earth, the chief constituent of which is the mineral attapulgite, may be used with some effect. Montmorillonite minerals may be used when the specie undergoes a dehydration of sufficient intensity during the select temperature range. The mineral may be dried prior to incorporation in compositions of the invention to eliminate all or a substantial portion of the free moisture. For most minerals this may be accomplished by heating for a suitable period of time, typically about an hour, at a temperature from about 100-250 C. When a specie undergoes an intense exothermic reaction during heating prior to its endothermic decomposition within the preferred temperature range, the mineral may be heat activated prior to inclusion in the tobacco composition to obviate the exothermic reaction during the smoking of a tobacco mixture including said mineral. Furthermore, it may be desirable to heat-treat a mineral to destroy its gelforming properties prior to using the mineral in a tobacco composition of my invention. Georgia-Florida fullers earth, for example, may be used either in its raw stage (about 50 percent V.M.), dried at about 250 C. to reduce its V.M. to about 19 percent, or more preferably, the earth may be dried at about 250 C. and heated at about 400 C. to destroy its gel-forming properties and reduce the V.M. to about 9 percent. The term V.M. as used herein refers to the volatile-matter which is the weight percent of the mineral eliminated by heating the mineral to essentially constant weight at about 1700 F. Bauxite or other naturally occurring aluminas may be dried but not activated such as by heating to temperatures of the order of 700-1000" C. for a time sufiicient to eliminate a substantial amount of the water of constitution. Solids, not accurately called minerals and which lose water of constitution within a suitable temperature range include, among others, hydrated oxides and silicates of alkaline earth metals. A preferred specie is hydrated lime which dehydrates within a temperature range depending to a large extent on associated impurities, the pure Ca(OH) dehydrating at about 580 C. Alumina gel and other synthetic aluminas such as Bayerite may be used, such material undergoing the reaction usually at between about 300-35 0 C. Hydrated calcium, magnesium or aluminum silicates or mixtures thereof may also be used.

A filter, either of the well-known type which is integral with the cigarette or of the holder type including a filter, may, if desired be employed in a smoking unit comprising tobacco mixtures of my invention. The filter may be fibrous and/or include adsorbents such as silica, clays or the like. The purpose of the filter is to prevent inspiration of any finely-divided material and/or mineral particles which may occur if the cigarette is subjected to dry, warm weather for prolonged periods. The filter interposes a bed of porous material, or the like, between the tobacco-material mixture and the smokers mouth and imprisons any particle which might otherwise be drawn into the smokers month. However, by proper selection of moisture content and, in some cases inclusion of humectant in the composition, the filter may be omitted.

When the adhesion of a particulate additive to the tobacco is inadequate a binder, such as sodium silicate or a pectic substance, suitably pectin derived from tobacco leaf, may be used to improve adhesion between the to- Example I In the example of my invention which follows, all cigarettes were mechanically smoked by the method described in detail in Industrial and Engineering Chemistry,

vol. 28, No. 7 in an article entitled Nature of Cigarette Smoke-Technic of Experimental Smoking, J. A. Bradford et al., pp. 836-839, inclusive (1936). Analysis of total tar content was made by collecting the tobacco smoke in a glass wool filter tube at room temperature and evacuating the tube at room temperature to eliminate moisture. Quantitative determination of tar yield was measured by calculation of the weight pick-up of the tube after removal of moisture therefrom. The mechanical smoking method employed approximates the conditions of human smoking sufiiciently for conclusions of in vitro experiments to be interpreted in vivo.

The outstanding reduction in total tar generated per unit of tobacco when a material and an endothermically dehydrating mineral are comming-led and dispersed through tobacco is shown in the example. Samples of cigarettes were prepared each comprising 0.90 grams of a popular-brand shredded tobacco blend packed in conventional cigarette paper. The moisture content of the tobacco blend was approximately 12 percent. Control cigarettes including no particulate additive were prepared. Other cigarettes were made including comminuted hydrated lime in amounts of 5 and 10 percent based on the weight of the tobacco. They were made up by homogeneously dispersing the dry additive with the tobacco shreds prior to packing. Similarly, a comminuted high alumina content siliceous material made in accordance Weight per Cigarette (Grams) Tar Yield per Cigarette Cigarette Tobacco Material Hydrated (Milli- Lime grams) 1. ControL". 0.90 35.3 2. Control +5 hydrated lime 0. 9O 0. &5 30. 1 3. Control material" 0.90 0.045 34. 2. 4. Control +5% hydrated lime +5% material 0.90 0.045 0.045 21.41

The results illustrate the outstanding benefits accruing from the combined addition of hydrated lime and material to cigarette tobacco with respect to total tar reduction. Furthermore; the in vivo smoking characteristics of the cigarette including a composition of my invention was distinguished by outstanding mildness and freedom from bite or harshness.

Example [I Compositionsof the invention were Prepared using the tobacco and kaolin material of Example I in combination with kaolin clay, an aluminum silicate mineral capable of endothermic dehydration. The method of EX- ample I. was duplicated. For comparison, a cigarette including kaolin. clay-as a single additive was prepared and the smoke analyzed. Tar yields obtained by analysis of. the condensate of mechanically smoked cigarettes are tabulated below. 7

Weight per Cigarette (Grams) Tar Yield per Cigarette Cigarette Tobacco Material Kaolin (Milligrams) 1. ControlCigarette 0.90 35.3 2. Control +5% material- 0. 90 0. 045 34. 2 3. Control +51% kaolin--. 0. 90 0. 045 35. 5 4. Control +5% kaolin 7 +5% material; 0.90 I 0 045 0. 045 31.2

7 Example 111 Q Another tobacco composition of the invention is pre pared by commingling tobacco shreds with diaspo-re using 2.5 parts of an acid-activated bentonite material (Filtrol), 2.5 parts of pulverized diaspore, previously dried at 225. C. and 95 parts by weight, of tobacco.

Example IV 7 parts by weight of pulverized Georgia-Florida fullers earth, dried at 225 C. to a volatile matter about 19% is commingled with 3 parts of pulverized kaolin ma.

terial prepared in accordance with the aforementioned copending patent application of Robinson et al. The mixture is dispersed with parts by weight of tobacco shreds. to provide another composition of my invention.

It will be understood the invention is not restricted to the method of commingling the tobacco and additives described in the example, any suitable means for intimately associating the components being satisfactory. For example, a slurry of additive particles may be added to leaf or particulated tobacco, suitably by spraying a slurry oi the particles onto the tobacco. Likewise the additives can be incorporated into so-called homogenized leaf tobacco by forming comminuted tobacco and additives into.

a coherent sheet-like mass in the presence of a suitable binder.

Obviously, many modifications and variations of the.

2. A cigarette comprising a paper wrapper envelopin the smoking mixture ofcla m 1. V

References Cited in the file of this patent UNITED STATES PATENTS 1,972,718 Sharlit Sept. 4, 1934 2,003,690 Lewton June-4, 1935 2,007,407 Sadler July 9, 1935 2,108,860 Kauffman Feb. 22, 1938 2,114,281 Allen Apr. 19, 1938 2,282,922 Ahlberg et al. May 12, 1942. 2,706,695 Frankenburg Apr. 19, 1955 2,839,065

OTHER REFERENCES Mellor, I. W.: A. comprehensive Treatise on Inorganic and Theoretic. Chemistry, vol. 6. Page 495 especially cited. Published by Longman, Green and 60., 1925.

Milton June 17,1958

Claims (1)

1. A SMOKING MIXTURE COMPRISING SHREDS OF TOBACCO COMMINGLED WITH A SMALL AMOUNT OF A FINELY DIVIDED MIXTURE OF KAOLIN CLAY AND KAOLIN CLAY WHICH HAS BEEN REACTED WITH SULFURIC ACID AND THEN THERMALLY DESULFATED WITHOUT LEACHING OF WATER-SOLUBLE REACTION PRODUCTS.