US3046996A - Process for affixing particulated mineral-type material to tobacco - Google Patents

Description

July 31, 1962 w. w. GARY 3,046,996

PROCESS FOR AFF'IXING PARTICULATED MINERAL-TYPE MATERIAL TO TOBACCO Filed Sept. 24, 1957 F G. I

VISCOUS HUMECTANT FINELY DIVIDED MINERAL PARTICLES SLURRYING TO COAT MINERAL PARTICLES WITH HUMECTANT SPRAYING SLURRY UNDER PRESSURE m TOBACCO CONTAIN m s ADHERENT PARTICLES OF HUMECTANT COATED MINERAL.

TOBACCO FIG. 2

VISCOUS HUMECTANT FINELY DIVIDED MINERAL PARTICLES SLURRYING TO COAT MINERAL PARTICLES WITH HUMECTANT ADJUSTING SLURRY TO SPRAYABLE CONSISTENCY WATER SPRAYING SLURRY CCO UNDER PRESSURE TOBACCO CONTAINING ADHERENT PARTICLES OF HUMECTANT COATED MINERAL INVENTOR. WRIGHT W. GARY ATTORNEY 3,4539% Patented July 31, 1962 3,046 996 PROCESS FOR AFFlXiNG PARTICULATED MEIERAL-TYHE MATERIAL T TGBACCO Wright W. Gary, Princeton, N.J., assignor to Minerals 81 Chemicals Philipp Corporation, a corporation of Maryland Filed Sept. 24, 1957, Ser. No. 685,819 5 Claims. (Cl. 131-140) evidence has evoked considerable effort directed to the elimination of potential carcinogens from the main stream of tobacco smoke either prior to or simultaneous with the pyrogenesis of the deleterious substances. Many methods for eliminating deleterious substances involve the comingling of finely-divided minerals or mineral-type materials with the tobacco in the smoking unit. Some of these materials are adapted to act as carriers for additives in the cigarette or the like when commingled with the tobacco. It has been established that high temperatures favor the generation of the potential carcinogens which are, in general, high-molecular weight polycyclic aromatics, probably py-rogenetically generated from allphatic precursors thought to be resident in the wax resident in the cutin and rays of the tobacco. Other finelydivided materials which has been suggested in the prior art to eliminate deleterious substances such as certain alkaloids from the main stream of tobacco smoke include certain sorptive material of natural or synthetic origin, such as for example, silica gel, certain naturally occurring clays, either in their raw state or heat or acid-treated, alumina gel, etc.

The term mineral-type as used herein refers to any particulated solid comingled with tobacco for any purpose and includes also those true minerals of natural origin, clays including mineral constituents, those synthetically prepared inorganic materials such as alumina gel, treated mineral materials, and the like. The term encompasses also acid-activated kaolin clay hereafter described as. well as other materials of the type used as catalysts in hydrocarbon conversion processes, such as are produced synthetically from silica and metallic oxides or by acid activation of bentonite clays or even activation of kaolin clay with leaching of soluble salts. Likewise the terms highly particulated and finely-divided have reference to a particle size of about 100 microns or less and includes powdered materials and microspherical or otherwise shaped material.

Prior art methods of applying such materials to tobacco include dusting of the tobacco or treating the tobacco in leaf or particulated form with an aqueous slurry of the finely-divided mineral-type material and dewatering the resultant mixture. Both methods suffer from the disadvantage of leaving the finely-divided material unbondcd to the tobacco in the absence of considerable moisture and hence free to dust-off during the subsequent processing to which the tobacco is subjected. Furthermore, thes methods fail Where uniform distribution of particulated mineral-type material on the tobacco in the consumers product is required, since during processing or storage the particles form segregated strata, channels or the like in the smoking unit. It is evident that it is highly advantageous to the efiicient performance of these powders that they be uniformly distributed on and afiixed to the tobacco.

Furthermore, dust problems are encountered in the handling and processing of tobacco in the presence of such fine materials in an unbonded mobile condition.

A highly etficient method for. coating or otherwise covering the surface of a solid material with a liquid is by spraying. Spraying not only provides a method for controlled distribution of material on a surface but, because the coating liquid impacts the base material with pressure the bonding therebetween is improved. When finelydivided material is slurried the slurry is capable of being sprayed by forcing the slurry through a nozzle or impinging the slurry on a rotating disc or the like. However, when a dilute slurry, that is a slurry containing less than about 25 percent solids, of mineral-type materials with which my invention is concerned is sprayed on tobacco the excess water is deposited on the tobacco and must be removed therefrom, this necessitating a costly operation in which some of mineraltype material is lost. Furthermore, when the moisture content of the de Watered mixture of catalyst and mineral-type material is reduced the particulated mineral-type material is free to dust oflf. When an aqueous slurry having a high-solids content, for example a 40% solids slurry, is sprayed the solids issue from the nozzle or other spray device as a jet of substantially dry particles due to the flash vaporization of the Water of the slurry; when more than trace amounts of such solids are coated on tobacco by spraying at sufiicient pressure to adequately coat the tobacco a severe dust hazard is created.

Accordingly, it is a principal object of the invention to teach a novel method for ailixing highly patticulated mineral-type materials to tobacco leaf, comminuted tobacco or homogenized tobacco, which method improves the adhesion of the finely divided solid to the tobacco and substantially obviates the dusting problem.

It is another and important object of the invention to teach a method for spraying tobacco particles with a coating of highly particulated materials whereby the particles issue as a jet of dispersed solids coated with an agent capable of bonding the solids to tobacco.

Another object of the invention is the preparation of Unique smoking mixtures and smoking units containing the same in which a particulated mineral is aflixed to tobacco by a film of humectant interposed between said mineral and the tobacco surface.

Briefly, I have discovered that finely-divided mineraltype particles may be applied to tobacco by spraying a slurry of said mineral in a humeotant or, more preferably, a slurry of said mineral in a water-humectant vehicle. The addition of humectants to smoking tobacco to impart moisture retention capacity to the tobacco is old in the.

art. The term humectant as used herein refers to hygroscopic, water-miscible polyoxygenated compounds, usually polyhydric alcohols such as glycerine, glycols (ethylene glycol, propylene glycol), and sorbitol or glycol ethers. These humectants useful in the practice of my invention are at room temperature viscous water-miscible liquids, or as in the case of sorbitol, for example, are readily rendered viscous liquids by small additions of Water or liquid humectants. In general from about 1 to 6 percent, and preferably 2 to 4 percent, of humectant, based on the weight of the tobacco is used in the manufacture of cigarettes Whereas larger quantities, such as 10 to 15 per cent, based on the weight of the tobacco is used in the manufacture of cigars since in the latter usage the humectant functions as a plasticizer. When the mineraltype material is slurried in humectant or 'hurnectant-Water solution and passed through a nozzle or other spray device the mineral-type material is ejected as a particle coated with humectant or aqueous humectant solution. When said humectant coated particle impinges a surface of tobacco at high velocity the ability of the viscous humectant to'bond the particle to the tobacco surface is improved over the bonding achieved were that coated particle to contact the surface without impact. The invention will be further described with reference to the attached drawings. FIGURE 1 represents .a diagrammatic flow sheet of a process for aflixing mineral-type particles to tobacco in accordance with this invention. A preferred method of operation in accordance with the invention is shown in FIGURE 2, which represents a diagrammatic flow sheet of another form of the process.

More specifically my invention is practiced by slurrying a finely-divided mineral-type material in a humectant, humectant mixture or in a humectant-water mixture. In general it is desirable to add only as much water to the humectant as is required to make both the mineral-type particles slurriable and the resultant slurry sprayable.

"When the mineral-type material is of the class of ma; 'tBIIBlS which may be flocculated or deflocculated in the humectant or humectant-water mixture asmall quantity of deflocculating agent may be used to lower the viscosity of the slurry so that a higher solids content slurry may be sent through the sprayer. It is a particularly advantageous practice to add the deflocculating agent to the slurriable mixture when the nature of the solids is such that relatively large quantities of water or water-humectant mixture would be required to slurry the solids. The use of large quantities of water in the slurry is to be avoided since excess water is'entrained in the tobacco and must be removed therefrom. The dollocculating agent will depend of course on the material to be treated. Examples'of deflocculating agents which may be used for deflocculating various flocculant materials are tetrasodium pyrophosphate, disodium dehydrogen pyrophosphate, ammonium hydroxide, sodium hex-ametaphosphate, sodium tripolyphosphate, sodium or calcium lignosulfonate napthalene sulfonicacid, certain citrates and the like. Ordinarily about 0.20 to 2.00 percent of deflocculant, based on the dry weight of the solid to be slurried, is used. The amount of solids in the slurry also depends, inter alia, on the viscosity of the liquids used, the specific gravity and particle size and shape of the solids, porosity of the solids, spraying pressure employed, size of spray opening, and moisture content of the tobacco. Hence the optimum ratio of solids to total liquids (or liquifiable materials such as for example sorbitol) is best determined by experiments designed to ascertain the maximum solids slurriable in the liquid and the maximum viscosity sprayable through the particular spraying apparatus. v The optimum quantities of mineral-type particles and of humectant applied to a specific quantity of tobacco are predetermined quantities predicated on the characteristics of the smoking mixture including the same. When the quantity of humectant called for in the tobacco formulation is insutficient for slurrying the mineral-type material, or, where the humectant is a solid, Water must be added to the materials to form the slurry. In general,'the

spraying operation is more dusflfree and the adherence of the minerahtype material to the tobacco is improved when the humectant is present in the slurry in an amount of at least about 50% by weight of the mineral-type materials and more preferably at least about 100% by weight. The maximum quantity of humectant used is of course predicated on the optimum humectant present in the tobacco.

It will be understood that the tobacco may be in the form of leaf, shredded or otherwise particulatedtobacco, or homogenized sheet or particulated tobacco made from homogenized sheet. Where uniform coating of the tobacco surface is important the tobacco should be agitated while the spray is applied thereto to ensure thorough distribution of the sprayed material on all of the surfaces of the tobacco. This may be done directing the spray to tobacco placed in a rotary tumbler.

In a preferred embodiment of the invention the high alumina content acid-activated kaolin clay prepared according to practices taught in the copending US. application of Serial No. 490,128, filed'February 23, 1955 by Alfred J. Robinson and James V. Weir, now Patent 2,967,157 is slurried in a mixture comprising sufiicient humectant to satisfy the requirements of the ultimate tobacco composition and to aflix the acid-activated kaolin clay to the tobacco surface and requisite water to slurry the solids. The slurry is sprayed on tobacco. The resultant composition comprises a major portion of tobacco the free surfaces of which are coated with particles of acid-activated kaolin clay, the adherence of the particles to the tobacco being promoted by the filmofaqueous humectant solution coating the particle. The value of intimately associating acid-activated kaolin clay with tobacco is treated in a copending US. patent application of Serial No. 683,946, filed September 16, 1957, 'by Wright W. Gary et a1. now Patent 2,967,118. In accordance with the invention of the copending patent application of Gary et al., the acid-activated clay is incorporated in tobacco in amount of 0.5 to 15 percent of the weight of the tobacco, and preferably in the amount of 2 to 10 percent. very finely divided particles, usually finer than about 10 microns and preferably having a substantial portion of particles between 0.5 and 2 microns.

The following examples are given only for the sake of further illustrating the invention and are not be construed as limiting the invention thereto but may be otherwise variously practiced within the scope of the appended claims. 7 Example I of acid-activated kaolin clay and 4 percent of humectant (2% ethylene glycol and 2% glycerol), based on the weight of the tobacco. In one run the acid-activated kaolin clay is made up into a 7 percent solids slurry and in a comparative run a 33 percent solids slurry is made. The slurries were prepared by agitating the following:

Slurry 1 Slurry 2 Water --pts. by wt 50 25 Humectant: V

50% Ethylene GlycoL- 4 25 50% Glycerol V Aeidaetivated Kaolin Clay. 4 25 Tetrasodium Pyrophosphate 0.03 08 The slurries were sprayed at 10 psi. into an enclosed vessel containing comminuted aged tobacco using sufiicient quantity of each slurry to deposit 4 percent acidactivated kaolin clay, based on the weight of the tobacco. The acid-activated kaolin clay was sufficiently adherent to the tobacco that it was not readily displaced therefrom by agitating the mixture. The free moisture of the tobacco untreated was 9.67 percent, whereas that of the tobacco sprayed with slurry 1 was 34.7 percent and the free moisture of tobacco sprayed with slurry 2 was found to be 12.65 percent. 7

When a comparable quantity of acid-activated kaolin clay was put on the tobacco by spraying a 40 percent solids slurry in Water in the absence of humectant, it was found that the particles did not adhere to the tobacco. The acid-activated kaolin clay issued from the spray was a fine mist of substantially dry solids and the dust thus created was ofiensive.

Example 11 Slurry 2 of Example I was reformulated substituting The activated clay is employed in the form of precipitated calcium carbonate for the acid-activated kaolin clay. The resultant slurry was too viscous to be sprayed so that additional parts of water was mixed therein to provide a 25% solids slurry. This slurry was sprayed onto the agitated tobacco in quantity sufficient to put 4 percent of calcium carbonate on the tobacco, :based on the weight of the tobacco.

It will be understood that my invention is described above in its broadest aspect and is susceptible to numerous variations without departing from the spirit and the scope of the invention. For example, at least one of the following may be incorporated in the sprayable slurry and be subsequently deposited on the tobacco surface in a total amount of from about 5 to 15 percent based on the weight of the tobacco: licorice, invert sugar, cocoa.

, Where for aesthetic reasons it is desirable to drably color the activated clay, molasses, preferably bl-ackstrap, may be used in lieu of the invert sugar in an amount up to about 5% by weight of the tobacco. Or the slurry itself may be drably colored with a non-toxic dye or pigment,

such as for example a melaninoid or tannintype pigment.

I claim:

1. A method of aifixing a finely divided mineral-type material on tobacco which comprises forming a slurry of sprayable consistency and comprising essentially finely divided particles of a mineral-type material and at least one viscous humectant in amount sufiicient to coat said finely divided particles, and spraying said slurry onto tobacco under conditions such that said finely divided particles impinge surfaces of said tobacco while said particles are coated with said viscous humectant whereby said finely divided particles adhere to said tobacco when impinged thereon.

2. A method of atfixing a finely divided mineral-type material on tobacco which comprises incorporating sufiicient water to form a slurry of sprayable consistency with a system comprising essentially finely divided particles of a mineral-type material and at least one viscous humectant in amount sufiicient to coat said finely divided particles, and spraying said slurry onto tobacco under conditions such that said finely divided particles impinge surfaces of said tobacco while said particles are coated with a film of an aqueous solution of said viscous humectant whereby said finely divided particles adhere to said tobacco when impinged thereon.

3. A method of afiixing a finely divided mineral-type material to tobacco which comprises incorporating sufficient Water to form a slurry of sprayable consistency with a system comprising essentially finely divided particles of a mineral-type material and at least one viscous humectant in amount sulficient to coat said finely divided particles, and spraying said slurry onto tobacco under pressure, whereby when said finely divided particles impinge surfaces of said tobacco said particles are coated with an aqueous solution of said humectant and thereby adhere to surfaces of said tobacco.

4. A method of affixing a finely divided mineral-type material to tobacco which comprises incorporating sufficient water with a system comprising finely divided particles of mineral-type material and at least one viscous humectant to form a slurry of sprayable consistency, said humectant being the sole adhesive material in said system and being present in amount sufficient to coat said finely divided particles, and spraying said slurry onto tobacco under pressure, whereby when said finely divided particles impinge surfaces of said tobacco they are coated with an aqueous solution of said viscous humectant and thereby adhere to said tobacco without drying the sprayed tobacco.

5. A method of affixing a finely divided mineral-type material to tobacco which comprises incorporating sufficient water with a system comprising finely divided particles of mineral-type material and at least one viscous humectant to form a slurry of sprayable consistency, said humectant being the sole adhesive material in said system and being present in an amount of at least about 50 percent by weight of said finely divided particles, and spraying said slurry onto tobacco under pressure, whereby when said finely divided particles impinge surfaces of said tobacco they are coated with an aqueous solution of said viscous humectant and thereby adhere to said tobacco.

References Cited in the file of this patent UNITED STATES PATENTS 1,961,866 Rocker June 5, 1934 2,003,690 Lewton June 4, 1935 2,108,860 7 Kaufiman Feb. 22, 1938 2,114,281 Allen Apr. 19, 1938 2,310,538 Musher Feb. 9, 1943 2,483,418 Kamlet Oct. 4, 1949 2,776,916 Ericsson Jan. 8,, 1957 2,797,689 Frankenburg July 2, 1957 2,839,065 Milton June 17, 1958 2,840,085 Detert June 24, 1958 2,881,770 Touey Apr. 14, 1959 FOREIGN PATENTS 485,388 Canada Apr. 20, 1949 1,003,102 France Nov. 14, 1951 1,115,647 France Jan. 9, 1956 838,419 Germany May 8, 1952

Claims (1)

1. A METHOD OF AFFIXING A FINELY DIVIDED MINERAL-TYPE MATERIAL ON TOBACCO WHICH COMPRISES FORMING A SLURRY OF SPRAYABLE CONSISTENCY AND COMPRISING ESSENTIALLY FINELY DIVIDED PARTICLES OF A MINERAL-TYPE MATERIAL AND AT LEAST ONE VISCOUS HUMECTANT IN AMOUNT SUFFICIENT TO COAT SAID FINELY DIVIDED PARTICLES, AND SPRAYING SAID SLURRY ONTO TOBACCO UNDER CONDITIONS SUCH THAT SAID FINELY DIVIDED PARTICLES IMPINGE SURFACES OF SAID TOBACCO WHILE SAID PARTICLES ARE COATED WITH SAID VISCOUS HUMECTANT WHEREBY SAID FINELY DIVIDED PARTICLES ADHERE TO SAID TOBACCO WHEN IMPINGED THEREON.

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