US3464420A - Smoking tobacco composition - Google Patents

Description

nited States Patent 3,464,420 SMOKING TOBACCO COMPOSITION George I. Klein, Larchmont, N.Y., assignor to Staulfer Chemical Company, New York, N.Y., a corporation of Delaware No Drawing. Continuation-impart of abandoned application Ser. No. 665,216, Sept. 5, 1967. This application Oct. 25, 1968, Ser. No. 770,808

Int. Cl. A24]: 3/08, 13/02 U.S. Cl. 13117 7 Claims ABSTRACT OF THE DISCLOSURE Smoking tobacco compositions are provided exhibiting improved filtration properties. The compositions of this invention comprise comminuted tobacco leaf and hydroxy apatite. In the preferred embodiments of this invention, the hydroxy apatite is used having an average particle size of from about in to about 2,000,u in diameter and is present in the composition in amounts up to about 25% by weight based on the weight of the tobacco.

This application is a continuation-in-part of application Ser. No. 665,216, filed Sept. 5, 1967, now abandoned.

This invention relates to smoking tobacco compositions exhibiting enhanced physical and chemical filtration properties. More particularly, this invention relates to tobacco based compositions containing an inert, inorganic, noncombustible, non-toxic particulate capable of enhancing the normal filtering properties of the tobacco mechanically and capable of removing acidic components chemically and other organic components by adsorption.

The use of tobacco, its reported ill effects and the many attempts to overcome these effects by filtration are too Well known to require elaborate discussion here. Filters which have been proposed for cigarettes have been installed at the end of the cigarette and have usually been mecahnical filters designed to remove particulate material from the smoke. Such filters have usually been fibrous in nature, although charcoal has been employed, as has Water. The fibrous filters have functioned in the same manner as the tobacco itself, i.e., as mechanical filtersa1though admittedly more eflicient. Pipe filters generally comprise a paper cartridge inserted in the stem of a specially designed pipe to serve about the same function.

It should be noted that a highly elficient filtration device in a cigarette or other tobacco product is undesirable.

Such a filter would leave the smoker inhaling warm air. What is desired is an efiicient selective filtration means which removes as much nicotine and aromatics as possible, but which permits the relatively non-toxic components of the smoke through to provide a satisfactory flavor to the smoker.

In accordance with this invention, it has been found that an admixture of normally comminuted tobacco leaves and from about 0.10 to about 25.0 parts by weight hydroxy apatite provide enhanced self-filtering properties to the tobacco. The compositions of this invention can be effectively used for smoking in pipes, cigars and cigarettes with or without other filtering devices, such as are normally known to the art.

By the term comminuted tobacco leaves is meant tobacco leaves as they are normally cured for smoking chopped, ground or shredded for use in the particular 3,464,42 Patented Sept. 2, 1969 form desired. For example, cigarette tobacco is normally shredded. Pipe tobacco is normally chopped or sliced from plug and rubbed, or is used as flakes cut from the leaves.

The hydroxy apatite utilized in the conduct of the present invention can be represented by the formula:

will be used hereinafter as representative of the hydroxy apatites used in this invention.

The hydroxy apatite used herein is particulate, preferably having an average particle size from about 2,000,11. to about 5,u in diameter, although particles having diameters from about 800 to about 50 inclusive, are most preferred, as such particle size range provide excellent filtration. While larger and smaller particles than those specified can be used, they are less effective in the compositions of this invention.

In more general terms, the particle size can be stated in terms of mesh size. For example, it is preferred that the particle size of the hydroxy apatite be sufficiently small that it passes a 12-mesh screen and yet sufilciently large that it rests on a IOU-mesh screen.

While the surface area of the calcium hydroxy apatite can also vary over a wide range, it has been found that materials having high surface areas provide enhanced smoke filtration. Accordingly, it is preferred that the hydroxy apatites exhibit a B.E.T. surface area more than 50 (meters) per gram. B.E.T. surface area is the Brunauer, Emmet, and Teller Method for Determining Surface Area as described in their article published in I. Am. Chem. Soc., 60, 309-319 (1938).

The hydroxy apatite material is conveniently prepared by precipitation from aqueous solution at a pH of 7.0 to 7.5. This preparation can be exemplified by the reaction mechanism which follows:

Hydroxy apatite prepared in this manner is granular and highly porous. This material has been found to function in three ways in the filtration of gas. First, the material filters mechanically. Second, this material effects a high degree of adsorption and, third, this material reacts With acidic components in the gas effectively binding them and removing them from the gas stream.

As has been indicated above, the calcium hydroxy apatite is non-toxic to the extent that it is eddible. These materials are also non-combustible inorganic compounds. These properties make the hydroxy apatites ideally suitable for use in the filtration of tobacco smoke as set forth in this invention.

The hydroxy apatite component can be used in amounts up to about 25 percent by weight based on the weight of the tobacco. Amounts greater than this tend to adversely affect the combustion of the tobacco. Amounts less than 5 percent by weight can be used, if desired, but provide less effective filtration. If, however, auxiliary filtration is employed, such lesser amounts can be more effectively used. Accordingly, amounts of from about 0.5 to about 25 percent by weight can be used.

In smoking, the compositions of this invention, the hydroxy apatites being non-combustible, fall with the ash or become part of the tobacco-ash residue. These compositions represent an effective and low cost means of providing filtration to tobacco without requiring a filter, although as indicated above, these tobacco compositions can be used with other filtration devices to provide enhanced filtration.

The tables below set forth the approximate composition of cigarette smoke.

Cigarette smoke is a heterogeneous mixture of gases, uncondensed vapor and liquid particulate matter. As it enters the mouth, the smoke is a concentrated aerosol with billions of particles per cubic centimeter. The median size of the particle is approximately 0.5 micron. Tabulated below are the major classes of compounds in the particulate and gaseous phases as reported in the Report of the Advisory Committee to the Surgeon General of the Public Health Service.

(A) Particulate phase No. of Class Percent comp. 'Ioxication on 11mg Acids 7. 7-12. 8 25 Some irritant. Glycerol, glycol, alcohols. 5. 3-8. 3 18 Possible irritation. Aldehydes and ketones. 8. 21 Some irritant. Aliphatic hydrocarbons 4. 9 64 Do. Aromatic hydrocarbons-.. 0. 44 81 Some carc1n0gen1c. Phenols 1. 03. 8 45 Irritant and cocarcrnogenic.

(B) Gaseous phase The gaseous phase of cigarette smoke amounts for 60% of the total cigarette smoke. Seven compounds make up 98.9 mol percent of the gas phase.

M01 percent Carcinogenic materials have been isolated from cigarette smoke in addition to the above:

ag/ 1,000 cigarettes Benzo (a) pyrene 16 Dibenzo (a,i) pyrene 10 Dibenzo (a,h) pyrene 4 Benzo (c) phenanthrene The filtration media of this invention effectively removes acidic components from tobacco smoke chemical reaction. It removes many of the organic liquid particulates from the smoke by adsorption, a mechanical filtration.

The granular hydroxy apatite is desirably intimately admixed With the tobacco. This is effectively accomplished by tumbling or any other conventional mixing or blending means known in the art.

It is usually desirable that the hydroxy apatite be incorporated with the tobacco when the tobacco is moist in order to avoid separation. In this respect, binder additives can be added in small amounts. These additives include sugar syrups, molasses and the like.

Hydroxy apatite is prepared by the addition of dilute phosphoric acid (9.0-20.8%) to a slurry of milk of lime [Ca(OH) containing 8l2% calcium hydroxide until the pH of the neutralized solution is 7.0 to 7.5. This results is a suspension of hydroxy apatite which is filtered, dried and milled to a specified particle size. Drying can be effected by any conventional means such as spray drying, tray drying, rotary drying and the like.

In this respect, it should be noted that calcium hydroxy apatites having mole ratios of CaO/P 0 from about 3.20 to about 4.0 are preferred and those having mole ratio of from about 3.25 to about 4.0 are most preferred.

Additionally, when the calcium hydroxy apatite has been formed in solution at a pH of about 7, it can be modified by adding a small amount of sodium or potassium hydroxide solution to raise the pH to about 8 to 11, if desired.

The surface area of the hydroxy apatites can also be increased through modification of the conditions of preparation. For example, the neutralization can be conducted in the presence of a protective colloid such as gelatin or carboxy methyl cellulose and the resultant material can be dried at relatively low temperatures under vacuum at, for example, room temperature. Alternatively, this material can be freeze dried to retain the maximum cell structure.

Variations can be made from the pH specified above which would result in unneutralized calcium hydroxide, which will not materially affect the properties of the hydroxy apatite for use in the subject invention.

The neutralization can be conducted at temperatures from 25 C. to C.

In the example which follows and throughout this specification all parts and percentages are by weight unless otherwise specified.

Example A 10% aqueous solution of phosphoric acid was slowly added to a 10% aqueous slurry of 57 grams of calcium hydroxide until the pH of the reaction solution is essentially neutral, i.e., about 7.0. Both solution and slurry are maintained at about 35 C. The reaction mixture contains a suspension of hydroxy apatite which is subsequently filtered, washed and dried. The dried hydroxy apatite is subsequently ground to an average particle size of from about 5 to 2,000 This material is then dispersed in cigarette tobacco by tumbling.

The tin hydroxy apatites and strontium hydroxy apatites are prepared in a manner identical to that set out above except that a stoichiometric amount of a soluble tin or strontium salt is added to the acid solution or calcium hydroxide slurry before combining the solutions. The nitrates of these metals can be effectively used.

While naturally occurring hydroxy apatites can also be used in this invention provided they are ground to the proper size, it is preferred to use the prepared and precipitated hydroxy apatites as these materials provide enhance filtration properties.

What is claimed is:

I. A composition for smoking comprising comminuted tobacco leaves and a granular porous hydroxy apatite having an average particles size of from about 2,000 to about 5 in diameter.

2. The composition of claim 1 wherein the hydroxy apatite is calcium hydroxy apatite.

3. The composition of claim 1 wherein the 'hydroxy apatite is tin hydroXy apatite.

4. The composition of claim 1 wherein the hydroxy apatite is strontium hydroXy apatite.

5. The composition of claim 1 wherein the porous hydroxy apatite has an average particle size of from about 800 4 to about 50,, inclusive, and a B.E.T. surface area greater than 50 (meters) 2 per gram.

6. The composition of claim 1 wherein the hydroxy apatite component is present in an amount of from about 0.5 to about 25% by weight based on the tobacco of the composition.

7. A cigarette tobacco composition comprising shredded cured tobacco leaves and granular porous calcium hydroxy apatite having an average particle size of from about 2,000 microns to 5 microns and a B.E.T. surface area greater than 50 (meters) per gram, said granular porous calcium hydroxy apatite being present in an amount of from about 5 to about 25% by weight based on the tobacco of the composition.

References Cited UNITED STATES PATENTS 2,940,456 6/ 1960 Touey 131-266 2,914,072 11/1959 Tyrer et a1 13117 X 2,941,906 6/1960 Haden 13117 3,117,5'80 1/1964 Weisman 131-l7 X MELVIN D. REIN, Primary Examiner US. Cl. X.R.