US3322130A - Tobacco composition - Google Patents

Description

United States Patent O 3,322,130 TOBACCO COMPOSITION Hans W. P. Panzer, Stamford, and Andrew E. Carmellini, Brookfield, Conn., assignors to American Machine & Foundry Company, a corporation of New Jersey No Drawing. Filed Mar. 3, 1964, Ser. No. 349,139 1 Claim. (Cl. 131-17) This invention relates to improved manufactured tobacco and more particularly to reconstituted tobacco sheet compositions comprising finely divided tobacco and incorporating a modified methylated cellulose.

A large number of polysaccharide or carbohydrate adhesives have been proposed to bind together particles of tobacco. In addition to good mechanical binding properties and film forming properties, adhesives used for this purpose should impart to the tobacco sheet suitable resistance to water and should not discolor tobacco or change its aroma and flavor. Of importance, also, is the neutral burn character of tobacco additives. Such additives should not add any disagreeable flavor to tobacco smoke when incorporated into the tobacco composition in useful concentrations. Moreover, additives should not adversely affect the tobacco burn rate.

In accordance with the invention, a modified methyl cellulose, in which at least some of the hydroxy groups of the constituent glucose units are altered by the introduction of relatively hydrophobic groups, is employed to decrease the water sensitivity or hydrophilicity of the methylcellulose gum. Such hydrophobic groups replace hydrogen atoms of hydroxyl radicals in the glucose units which have not already been replaced by methyl radicals. The introduction of the proper hydrophobic substitueut as well as suitable amounts of the substituent is highly important to achieve the film properties wanted.

It is an object of the invention to provide a novel tobacco composition which includes a cellulose which has been altered to include methyl substituents as well as more hydrophobic substituents for the hydrogen atom of the hydroxyl radicals on the glucose units of the cellulose.

It is a more specific object of the invention to provide tobacco sheet compositions containing as an adhesive, cellulose modified to a relatively high degree of substitution with methyl substituents and further modified by ether or ester radicals, other than methyl, by reacting with appropriate acetylating or etherifying agents or both to decrease water sensitivity of the adhesive.

Additional objects will become apparent from the description of the invention which follows.

While the invention will be described in connection with tobacco sheet, the adhesive of the present invention may likewise be advantageously used with tobacco in other shapes such as rods, cylinders, plugs, shreds, and the like. Accordingly, it will be understood that the invention contemplates also tobacco manufacture of this kind.

In addition to the methylcellulose, modified to make it hydrophobic, as the adhesive for the tobacco, the invention may employ various additional ingredients or modifiers known in the art to be useful in making tobacco sheet. For example, a fibrous material such as alpha cellulose pulp, in an amount of from about 1% to about 10%, preferably from about 5% to about 8%, based on the total weight of the composition, may be used to furnish reinforcing fibers to increase the strength of the tobacco product. The invention also contemplates the inclusion in the tobacco composition of a suitable humectant such as glycerine, 1,2,6-hexanetriol and/ or propylene glycol and/or tetraethylene glycol or other polyethylene glycols in an amount of about 5% to 12% based on the total 7 Weight of the composition. Additionally, conventional 3,322,130 Patented May 30, 1967 burn and ash modifiers, flavoring agents, and the like may be incorporated.

Accordingly, the invention comprises a tobacco product and an adhesive binder therefor in which ethers or esters of methylcelullose may be used, or alternately methylcellulose which contains both ether and ester groups, in addition to the methylether group, in the same methylcellulose molecule may be used. Generally, the adhesive binder is employed in amounts from about 2% to about 35% based on the total weight of the composition, and preferably in amounts of from about 5% to about 20%. It will be apparent that the modified methylcellulose incorporated in tobacco, as taught by the invention, may be used in combination with other ingredients including other adhesives, cross-linking materials, plasticizers, etc.

In preparing the water desensitized modified methylcellulose adhesives of this invention, high molecular Weight cellulose may be converted in single or multi-stage processes to the corresponding compounds according to the known methods (e.g. Savage, Young, and Maasber-g, and Malrn and Hiatt in Cellulose and Celulose Derivatives, ed. Ott and Spurlin, Interscience Publishers, Inc., 1954, part II, ch. IX, 763 and 882). A preferred embodiment of this invention utilizes methylcellulose derivatives in which the methyl groups had been introduced first into the cellulose. The degree of substitution of methyl groups in the cellulose structure of the materials is generally in the range of about 1.0 to about 2.6. Methylcellulose having this degree of substitution may be treated to convert the remaining or unreacted hydroxy radicals, substituting therefor ester and/ or ether substitutents so that the modified methylcellulose thereupon attains a degree of substitution more nearly approaching 3.0.

Degree of substitution (D.S.) as used herein refers to the three replaceable hydrogen atoms of the available hydroxyl groups of the anhydro glucose monomeric unit of the cellulose molecule. The practical maximum degree of substitution is 3.0. The replacement of two of the hydrogens on the available hydroxyl groups for example gives a degree of substitution of 2.0.

In the preparation of the adhesives of the invention, methylcellulose whose degree of substitution is at least 1.0 and significantly less than the theoretical maximum of 3.0, is modified at the remaining hydroxyl groups of the glucose units so that the modified cellulose has the desired water insensitivity. Hence, the cellulose adhesive compounds contemplated by the invention comprise cellulose which has a degree of substitution, with methyl ether groups, of at least 1.0 and further characterized by having additional substituents for the hydrogen atoms of unsubstituted hydroxyl radicals, which render the modified cellulose less hydrophilic. In general, such substituents comprise ether substituents other than methyl and ester substituents. In particular, substituents of this kind include benzyl, alkyl radicals of 2-5 carbon atoms, substituted (and nonsubstituted hydroxyl groups) and carboxyalkyl groups containing 1-19 carbon atoms.

The modified cellulose product may be further defined in connection with the general formula:

wherein R R and R if not hydrogens, are substituents selected from the group consisting of hydrogen, alkyl 3 radicals of 25 carbon atoms, carboxyalkyl, or carboxyaryl radicals having a backbone of l to 19 carbon atoms, alkyl and acyl substituted hydroxyalkyl radicals and benzyl radicals and wherein the degree of methyl substitution at one or more of the R R and R positions is at least 1.0. 7

Suitable specific binders comprising the water resistant modified methylcelluloses contemplated by this generic formula include acetylmethylcellulose, methylhydroxyethylacetylcellulose, methylhydroxypropylacetylcellulose, ethylmethycellulose, n-propylmethylcellulose, benzylmethylcellulose and the like.

These hydrophobically modified adhesives, which may be prepared in dry or liquid form, are combined with tobacco fines by conventional techniques employed in the reconstituted tobacco art. When the adhesive is added in dry powdered form it is mixed intimately with the tobacco fines and to this mixture is thereafter added the other ingredients desired, e.g. humectants, fibrous pulp, etc. If the desensitized methylcellulose is added in dissolved form, it may be mixed with a humectant, such as glycerine or a mixture of humectants such as a glycerine-propylene glycol mixture. The dissolved adhesives are then mixed with the powdered tobacco fines. The comminuted tobacco when introduced may be in admixture with the fibrous material. Suitable solvents and dispersion systems for the adhesives are, for example, mixtures such as benzene-methanol, benzene-ethanol, toluene-methyl-ethyl alcohol or in some cases, ethyl alcohol-water systems.

In general, in preparing the tobacco compositions, the process involves conveying dry tobacco to an appropriate grinding mechanism such as a hammer-mill where it is dry ground until about 20% to of the resulting fragments would pass through a 140-mesh screen and until about 0.5% to 10% would remain in a 30-mesh screen. The proportions of coarse and fine tobacco particles produced thereby are variable at random within these limits and may depend on the ultimate intended use of the tobacco product formed, i.e. whether the tobacco will be shredded, used as cigar binder, as wrapper, etc.

A preferred procedure of compounding is to add the ground tobacco, with or without the humectant, under constant stirring to the water-desensitized methylcellu lose dissolved in an organic liquid solvent system. The resulting dispersion is then processed as is known in the art, as for example, by employing the means described in US. Patents 2,957,478 and 2,984,244.

The product, which may be in the shape of a fiat sheet, shred or leaf, is then dried and conditioned to a degree such that the moisture content approximately equals that of natural leaf tobacco in the manufacture of cigarettes and other smoking articles. The tensile strength of the products produced is, in most cases, superior to that of leaf tobacco, and similarly the thickness of a sheet of the finished composition is about that of natural leaf tobacco although more advantageous due to its improved uniformity. The ultimate moisture content, after drying is about that of natural leaf tobacco when ready for blending, i.e. about 8% to 13% by weight of the total composition.

The tobacco products of this invention may be in the form of shreds or filaments and as such are useful as filler in pipes, cigarettes, cigars and cigarillos. They may conveniently be blended with whole leaf tobacco in any proportion. The shreds may be extruded or cut from sheets made of the product. Such sheets are useful as cigar wrapper or binder or to package tobacco.

The organic solvents evaporated from the deposited sheet are easily recoverable by conventional processes and can be reused. High speed drying of the tobacco sheets is desirable in the manufacture and can be accomplished by means known in the production of reconstituted tobacco sheets.

The following examples are provided as further illustrations of the inventive concept. These examples are not to be construed as limitations on the invention. Partsre- One part of methylethylcellulose, prepared from high molecular weight cotton linters, having a methyloxy content of 36.2% and an ethyloxy content of 5.3% (viscosity 3000 cps., 2% solids in methanol-benzene, 1:2 v./v. Brookfield viscosirneter) was dissolved in a mixture of methanol and benzene. Then one part of humectant, tetraethylene glycol was added and completely dispersed in the solution. This was followed by five parts of ground Havana feed tobacco. The mixture, having a total solid content of 20%, was thoroughly homogenized and subsequently cast. The tobacco sheets were dried at room temperature and conditioned at relative humidity. A randomly chosen sheet of this cast had the following tensile strength properties:

Tensile strength, dry g./in 375 Tensile strength, wet g./in 170 Elongation, dry percent 29 Elongation, wet do 42 Sheet weight g./ft. 3.52

Example 2 One part of n-propylmethylcellulose with 35.6% methyloxy and 5.2% propyloxy (viscosity 1160 cps; 2% solids in benzene-methanol, 2:1 v./v.), one part of humectant, tetraethylene glycol, and five parts of ground tobacco were dispersed in a benzene-methanol solvent system.

Tobacco sheets were cast and dried. Properties of the tobacco foil after conditioning at 80% relative humidity are as follows:

Tensile strength, cond. at 80% RH. g./in 275 Tensile strength, wet g./in Elongation, cond. at 80% RH percent 20 Elongation, wet do 20 Sheet weight g./ft. 4,464

Increase in water resistivity over methylcellulose adhesive was more than one and a half-fold.

Example 3 The procedure of the foregoing example is substantially repeated except that a formulation of benzylmethylcellulose with 25.2% methyloxy and 13.26% benzyloxy (viscosity 800 cps.) was used instead of that of Example 2. The mechanical properties of the tobacco foil prepared with this adhesive and at 80% relative humidity were found to be as follows:

Tensile strength, cond. at 80% RH g./in 275 Tensile strength, wet g./in 235 Elongation, cond. at 80% RH. percent 7 Elongation, wet do 13 Sheet weight g./ft. 4.48

Improvement in water insensitivity over methylcellulose adhesive was three-fold.

Example 4 Acetylmethylcellulose produced by acetylation of methylcellulose in a conventional way and having a methoxy content of 25.0% and an acetyl content of 20.1% (Brookfield viscosity 940 cps., 2% solids) was employed as the adhesive component in a 121.5 adhesive:humectant:tobacco sheet formulation using tetralthyleneglycol as humectant. The physical data of this tobacco sheet dried and remoistened to 12% moisture is:

Break strength g./in., cond. 310 Break strength g./in., wet 280 Elongation, percent, cond. 8 Elongation, percent, wet Sheet weight g./ft. dry 4.85

Increase in Water resistivity over methylcellulose is more than three-fold.

Example 5 The procedure of Example 1 is substantially repeated using as the formulation a 1.0:0.5:4.5 adhesive, humectant and tobacco ratio, respectively. A commercially available methylcellulose (Dow MC-8000) having a degree of substitution of 2.2 is esterified by reacting with acetic anhydride until it is practically fully acetylated. This water desensitized methylcellulose is then employed as adhesive. As humectant, tetraethylene glycol is used. Tobacco sheets cast and dried have 75% tobacco content and have the following properties after conditioning at 80% relative humidity:

Moisture, percent 11.78 Break strength, gm./in., long. cond. 640 Break strength/in, trans. cond. 570 Break strength, grn./in., long. wet 515 Break strength, gm./in., trans. wet 405 Tensile factor, long. cond 140 Tensile factor, long. wet 113 Percent elongation, cond 17 Percent elongation, Wet 25 Sheet weight, gm./ft. dry 4.58 Porosity Nil The increase in water resistivity was more than six-fold over the control sample containing methylcellulose as the binder for the tobacco.

Example 6 The procedure of Example 5 was substantially repeated except acetylated methylhydroxypropylcellulose (D.S. methoxyl 1.4; D.S. hydroxypropyloxyl 0.2) was employed as adhesive binder. The sheet properties of the tobacco foil dried to the condition of that of Example 5 are as follows:

Moisture, percent 9.52 Break strength, gm./in., long. cond. 1510 Break strength, gm./in., trans. cond 1070 Break strength, gm./in., long. wet 640 Break strength, gm./in., trans. wet 455 Tensile factor, long. cond. 305 Tensile factor, long. wet 128 Percent elongation, cond. 23 Percent elongation, wet 33 Sheet weight, gm./ft. dry 4.98 Porosity Nil The improvement in hydrophobic property was com parable to that of Example 5. There was no adverse effect in the burn aroma of the reconstituted tobacco formed in each of the examples.

It will be apparent to those skilled in the art that vari- I References Cited UNITED STATES PATENTS 2,893,400 7/1959 Detert ea al. l3115 2,927,588 3/1960 Detert et al. 131--15 3,120,233 2/1964 Battista et al 131-17 OTHER REFERENCES Industrial Gums, by Whistler and BeMiller (text), published by the Academic Press, New York, 1959, pages 590 and 591.

SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner.