United States Patent: 3559655

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United States Patent	3,559,655
Briskin , et al.	February 2, 1971

OXIDIZED CELLULOSE SUBSTITUTE SMOKING MATERIAL AND METHOD OF MAKING SAME

Abstract

A process for the manufacture of a smoking product in which cellulose is oxidized and in which the oxidized cellulosic material is formulated to contain a mineralizing agent in the form of a strontium or barium oxalate, lactate, glycolate, diglycolate or pivalate in an amount within the range of 5--40 percent by weight of the smoking product and which may have further added thereto a minor amount of oxalic acid.

Inventors:	Briskin; Theodore S. (Beverly Hills, CA), Ward; Geoffrey R. (Beverly Hills, CA)
Assignee:	Sutton Research Corporation (Los Angeles, CA)
Appl. No.:	04/802,229
Filed:	February 25, 1969

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
595622	Nov., 1966	3447539

Current U.S. Class: 131/359 ; 162/139; 162/158

Current International Class: A24B 15/16 (20060101); A24B 15/00 (20060101); A24d 001/18 (); A24b 015/00 ()

Field of Search: 131/2,9,15,17,140,144 162/139,158

References Cited [Referenced By]

U.S. Patent Documents


3033895	October 1961	Grunwald
3461879	August 1969	Kirkland

Other References

N Irving Sax (Text) DANGEROUS PROPERTIES OF INDUSTRIAL MATERIALS (1968) Reinhold Pub. Co. Pages 448, 987 and 1134 cited.

Primary Examiner: Rein; Melvin D.

Parent Case Text

This application is a continuation-in-part of our copending application Ser. No. 595,622, filed Nov. 21, 1966, now U.S. Pat. No. 3,447,539, and entitled "Oxidized Cellulose Smokable Product and Ashing Ingredient."

Claims

We claim:

1. A process for the manufacture of smokable products comprising the steps of providing an oxidized cellulosic material and incorporating an ashing ingredient into the cellulosic material for producing a fine ash with the smokable product, in which the ashing ingredient is selected from the group consisting of the oxalate, lactate, glycolate, diglycolate, pivalate and tannate of strontium, barium, aluminum, titanium, lithium and silicon, or the lactate, glycolate, diglycolate and pivalate of calcium and magnesium, and mixtures thereof, and is present in an amount within the range of 5 to 45 percent by weight of the smokable product.

2. The process as claimed in claim 1 in which the ashing ingredient is incorporated before or after oxidation of the cellulose.

3. The process as claimed in claim 1 which includes the step of introducing 0.5 to 1.5 percent by weight of a compound selected from the group consisting of potassium oxalate and potassium hydrogen oxalate for controlling the burning rate of the smokable product.

4. The process as claimed in claim 1 which includes the step of introducing up to 0.5 percent by weight of free oxalic acid.

5. A process for the manufacture of smokable products comprising the steps of providing an oxidized cellulosic material and incorporating an ashing and mineralizing ingredient into the cellulosic material for producing a fine ash in the smoked product in which the ashing and mineralizing ingredient is selected from the group consisting of the oxalate, lactate, glycolate, diglycolate, pivalate and tannate of strontium, barium, aluminum, titanium, lithium and silicon or the lactate, glycolate, diglycolate and pivalate of calcium and magnesium and mixtures thereof, and is present in an amount to provide an ash content within the range of 15 to 25 percent by weight in the smoked product.

6. A smokable product comprising a charge of oxidized cellulosic material and an ashing ingredient incorporated therewith selected from the group consisting of the oxalate, lactate, glycolate, diglycolate, pivalate and tannate of strontium, barium, aluminum, titanium, lithium and silicon, or the lactate, glycolate, diglycolate and pivalate of calcium and magnesium, and mixtures thereof, the said ashing ingredient constituting between 5 to 45 percent by weight of the smokable product.

7. A smokable product as claimed in claim 6 which includes up to 0.5 percent by weight of free oxalic acid.

8. A smokable product as claimed in claim 6 which includes 0.5 to 1.5 percent by weight of a burning controlling agent selected from the group consisting of potassium oxalate and potassium hydrogen oxalate.

Description

There is an unquestionable appeal in smoking products. Thus, various smoking habits have been indulged in for centuries, and it is well known that current smoking habits involve a tremendous market.

Smoking products which include tobacco as a constituent have been subject to particular criticism. Accordingly, a large number of proposals have been made with a view toward developing smoking products which do not include tobacco. Generally speaking, these products involve the use of materials which do not contain drugs such as nicotine or potentially carcinogenic ingredients. Furthermore, attempts have been made to incorporate taste and aroma characteristics which are unobjectionable and which preferably correspond to tobacco taste and aroma.

It is a general object of this invention to provide improved materials suitable for use in manufacturing smoking products.

It is a more specific object of the invention to provide smoking products which are characterized by distinct advantages when compared with previously known smoking products, and it is a related object to provide improved procedures for the formation of materials to be employed in the production of such smoking products.

It is a specific object of the invention to provide procedures which are adapted to be employed in conjunction with the manufacture of a wide variety of materials considered suitable for use in smoking products whereby products can be rendered more desirable from the standpoint of smoking enjoyment and from the standpoint of comparative safety. Such materials, which may or may not be flavored, can be in the form of shreds or pellets for use in pipes, or in the form of leaves or sheets for use in structures analogous to cigars, or in the form of shreds or filaments for use in cigarettes. Such materials can be used alone or incorporated with other materials such as tobacco.

It is an additional object of this invention to provide for the production of a material which has suitable smoking characteristics from the standpoint of burning rate, and which is virtually neutral from the standpoint of odor and taste during burning, and which is believed to be free of harmful ingredients.

It is a further object of this invention to provide techniques for the use of a material of the type described in the foregoing object whereby the material can be employed as a basic constituent of smoking products.

It is a still further object of this invention to provide smoking products formed of the materials referred to above which include flavoring ingredients, preferably in a filter, whereby the product can be smoked with enjoyment and without fear.

These and other objects of this invention will appear hereinafter, and it will be understood that the specific examples included herein are provided for purposes of illustration and are not intended to limit the scope of the invention.

The instant invention includes processes involving the treatment of materials employed as ingredients in smoking products. It will be understood that the process of this invention is applicable to a variety of different types of ingredients, including tobacco. Various other materials, both natural and synthetic, considered suitable for forming all or part of a smoking product, can be treated in accordance with the procedures to be described. Materials such as papaya, lettuce, bagasse and corn silk are examples of materials which have been suggested as substitutes for all or part of the tobacco normally used for producing smoking products. The instant invention is applicable to all such materials as well as to a variety of other materials of the same or different characteristics. In general, such materials, suitable for use in the practice of this invention, may be included within the broad term of "cellulosic materials."

The invention contemplates the treatment of such materials by placing the materials in contact with certain specific minerals whereby the minerals become incorporated into the material. In accordance with one aspect of this invention, oxalate anions are incorporated or associated with the minerals to counteract the detrimental features of using such minerals. It is contemplated that related anions including lactate, glycolate, diglycolate, pivalate and tannate salts could be employed along with or in place of the oxalate. It will be understood, however, that the oxalate anions produce highly significant results and, therefore, most references herein will refer to the oxalates. Such references are intended, however, to serve as examples of contemplated use of the other anions mentioned.

In referring to the "incorporation" or "association" of the minerals with the material being treated, it will be understood that no specific limitation is intended. Diffusion within the fibers of the material treated has been recognized while presence of the materials in particulate form on the exterior of the fibers is also contemplated.

In a preferred form of the invention, the oxalate is associated with the material in the form of at least one salt of a metal selected from the group consisting of magnesium, calcium, strontium and barium. For example, magnesium oxalate and calcium oxalate may be present at the same time in association with the material being treated.

The oxalate operates to best advantage when various objectionable ingredients of the materials being treated are eliminated either by separate processing or through replacement during incorporation of oxalates. Many ingredients including hydroxides, carbonates and acetates and other organic salts of alkali and alkaline earth metals have been found to be objectionable in smoking products. The ingredients themselves may cause undesirable conditions during burning, such as undesirable odors, or the ingredients may react with other ingredients during burning to create the undesirable characteristics. In any event, it has been found that the substitution materials will reduce, and in some cases substantially eliminate, undesirable aspects of the materials.

The described mineralizing agents, as represented by the metal oxalates, can be incorporated into materials in amounts from about 5 percent to about 40 percent by weight, in which case highly significant improvements are achieved. No significant impairment of burning characteristics or ash characteristics is recognized when the oxalate additions are properly controlled. Since the oxalates will not react in an undesirable fashion during burning, the smoking products treated will retain their expected smoking characteristics while certain undesirable aspects can be reduced or eliminated.

The oxalates can be incorporated in the materials being treated in a variety of ways. As a specific example of a suitable treating procedure, for a material which already contains, say, calcium carbonate, a 5 percent oxalic acid solution may be employed. The solution may be either an aqueous or alcohol solution or a combination thereof, and the material being treated can be immersed in the solution so that the solute is absorbed into the fibers of the material. In the usual case, an exchange reaction will take place whereby oxalates will be incorporated in the material. Carbonic acid and the like, which are freed due to the reaction, can be volatilized during the reaction or can be washed out with suitable reagents, as a separate stage of the process.

The particular percentage of the acid solution is not critical. Stronger or weaker solutions can obviously be employed, and the treating times can be varied to provide ample opportunity to complete or substantially complete the incorporation of oxalate anions into the treated material.

After completion of the treatment described, the materials treated are preferably washed to provide for removal of any excess acids, including oxalic acid. Water, alcohol or other neutral solvents can be employed, depending upon the types of materials to be removed during the washing.

The above discussion has referred to the treatment of various smoking materials for purposes of providing some improvements therein. A preferred aspect of this invention relates, however, to the preparation of completely novel smoking products which have ideal characteristics not achievable in any presently available materials.

The devising of the novel smoking material of this invention involves the adjustment of various parameters, and this adjustment is complicated by their interaction upon each other. Thus, an ideal smoking device is normally characterized by a main stream of smoke and gases, a side stream which goes directly into the air from the burning zone, a preferred volume of visible smoke, a preferred burning rate, a minimum of flare (flaring up when lighting or inhaling deeply), a preferred volume of ash to shield the burning zone and prevent debris from dropping out, a preferred coherence level in the ash, and a preferred resilience both before and during usage.

The smoking device should also be free of materials which produce unpleasant odors and which might be injurious to health. In developing this invention, it was found that the purity of the carbohydrates when used as raw materials was apparently an essential factor in avoiding undesirable burning odors. Such odors apparently arose from the burning of proteins, sugars, chlorophyll, lignins, oils, waxes, resins, and latex residues. Traces of iron, calcium, magnesium, potassium and sodium compounds were also responsible for the generation of undesirable odors. The presence of lignins and proteins indicates the presence of aromatic nuclei which can condense to form carcinogens. Organic nitrogen compounds which are present can pyrolyze to form nitric oxides, nitriles, and cyano compounds which are highly toxic and irritating to the smoker's respiratory system.

In accordance with the practice of this invention, it is preferable to start with materials which are as concentrated in cellulose as possible. Such materials include cotton fibers and linters, flax, deligninized wood pulp, reconstituted cellulose such as viscose, rayon and cellophane. Such purified cellulose, however, is unsatisfactory for smoking purposes, despite its current use in cigarette papers, because of the very irritating aldehydes and acids that are evolved. This is very evident if a piece of cigarette paper is allowed to smolder and the smoke is then inhaled.

However, if the free methylol group in the cellulose unit is oxidized to a carboxyl group, the resultant oxidized cellulose yields on pyrolysis relatively very little tar and mainly water, carbon dioxide and carbon monoxide, indicating a relatively complete breakup of the cellulose rings. (Reference: Madorsky, S. L., V. E. Hart and S. Strauss, J. Research National Bureau Standards, 60, 343, 1958). Nitrogen dioxide is a reasonably specific reagent for effecting this oxidation. Oxidation of cellulose for purposes of forming cigarette products is disclosed in Canadian Pat. No. 702,918.

It will be understood that the oxidation treatment can be undertaken at various stages of the processing of the cellulose. In some instances, it is desirable to delay oxidation until a later stage of the processing so that the fiber strength of the cellulose will be maintained as long as possible. In some instances, however, the strength of the cellulose is not critical from a processing standpoint and, accordingly, the oxidation can be undertaken at an earlier stage of the processing.

Subsequent to oxidation, it is desirable to clean the oxidized cellulose. An alcohol solution can be employed for removing excess nitrogen dioxide and boiling of the oxidized cellulose in acetone also achieves the removal of various foreign materials which may not have been removable during the original processing of the cellulose.

An important feature of this invention involves the finding that calcium oxalate has an anion of sufficient strength and refractoriness to keep the calcium cation free from interaction with the other anions during the pyrolytic action. During the pyrolysis, the calcium oxalate decomposes to calcium carbonate without forming objectionable odors. Evidently this is at a sufficiently advanced stage in the pyrolysis that the calcium carbonate is not objectionable. Similarly, potassium organic salts are known to produce dimeric substances when pyrolyzed. In practice, we find that the potassium salt of oxidized cellulose produces a burning odor reminiscent of a smoky bonfire, and that the magnesium salt produces a burning leaf odor. In these examples also, the odor problem can be remedied by using the oxalate salts of these metals. Other useful cations include lithium, barium and strontium, and these can be rendered acceptable by the same technique. Although of the same family, sodium does not appear to become acceptable.

The incorporation of oxalates in the cellulose can take place either before or after oxidation. As previously discussed, the oxalates can be incorporated in various ways. If a substantially pure cellulose forms the starting product, then the oxalate incorporation can first involve soaking the cellulose in a mineral salt solution, for example, a 5 percent solution of calcium and magnesium acetate. The salt readily incorporates itself in the cellulose, and when this treatment is followed by soaking in an oxalic acid solution, the calcium and magnesium acetate will react with the oxalic acid to leave insoluble calcium and magnesium oxalates incorporated in the cellulose. Acetic acid, which is formed during the reaction, can be readily washed from the cellulose.

The manufacturing of the cellulose may also utilize the incorporation of oxalates instead of the commonly used carbonates. Some cellulose-manufacturing processes are suitable for the direct incorporation of oxalates in controlled amounts, and the use of such cellulose is contemplated by the instant invention.

The oxalate salt can also be added as such to the inside or the outside of the oxidized cellulose material either by direct application from a solution or, in the case of the insoluble calcium and magnesium salts, by the application of a solution in which the oxalate is in process of being generated. It can also be added by allowing the cellulosic material to absorb two reagents in sequence such that they interact in or on the fiber to form the desired oxalates.

It is well known that tobacco contains calcium and magnesium and potassium salts, and that it also contains a small amount of oxalic acid. Whether this invention is applied to tobacco or to other smoking materials, it is preferable that the cationic amount of oxalic anion is stoichiometrically related to the amount of metal such that the fixation of the metals is substantially complete, since even a small inadequacy may be noticeably detrimental. In fact, to ensure this, an excess of oxalic acid or other nonobjectionable oxalic compound, such as ammonium or amine oxalate is preferably added, or an oxalate generator such as an ester of oxalic acid, e.g. a condensate of oxalic acid and a glycol is employed. Such excess must not be great enough to cause other problems in the particular system being formulated, and the excess is usually less than 5 percent by weight of the treated material and preferably less than 0.5 percent by weight.

As suggested, several other organic acids are candidates for this role. These include glycolic, diglycolic, lactic, pivalic and tannic acids inasmuch as they fix the calcium and other such metal cations and protect them from the pyrolysis environment for a long enough period to prevent the undesirable odors which otherwise would characterize the calcium or other such metal cations. Similarly, generators of such acids can readily be conceived.

It has also been observed that during the pyrolysis of the oxidized cellulose samples having an oxidation level in the 90 to 100 percent range, a charring sometimes occurs in conjunction with a liquefaction of the material which smothers the glowing areas and causes the smoking system to go out.

If mineral-forming materials are dispersed internally throughout the oxidized cellulose, as contrasted with a situation where mineral appears on the outside of the combustible material, or interstitially, such minerals act as a reticulum to support the pyrolyzing material and this prevents the undesirable coagulative liquefaction and the system can then be kept alight by observing other suitable conditions. For this purpose, it is necessary to incorporate minerals to an extent such that an ash content of 15 to 25 percent results from such mineralization. Such mineral-forming materials include any which can be absorbed into the fiber and which can be generated inside the fiber, and which do not otherwise cause undesirable effects. We have found more specifically that the preferable materials include the oxalates, glycolates, diglycolates, lactates, pivalates and tannates of calcium, magnesium, lithium, barium and strontium. Aluminum, titanium and silicon compounds also have proved effective.

There is also some evidence that where potassium nitrate is present, it is converted by the polyanhydroglucuronic acid to the potassium salt thereof with liberation of nitric acid which is lost by evaporation. This may occur during application, drying, storage or pyrolysis.

It has been found by impregnating strands of oxidized cellulose with various salts, that potassium oxalate on oxidized cellulose has the same effect in sustaining a glow that potassium nitrate has on ordinary cellulose. Accordingly, a feature of the invention involves the incorporation of a small amount of potassium oxalate, or potassium hydrogen oxalate, in amounts up to 5 percent and preferably between 1/2 and 11/2 percent by weight.

The following description illustrates a typical process for the preparation of a smoking material in accordance with the instant invention:

EXAMPLE 1

A highly purified commercial grade of wood pulp is fabricated into a thin paper of a thickness comparable to commercial cigarette paper, 15 to 25 percent calcium carbonate powder being incorporated as a filler. This paper is shredded into strands of about two millimeters width and immersed in approximately one hundred times its weight of liquid nitrogen dioxide maintained at 20.degree. C. Immersion continues for about 5 to 10 days, or until testing indicates a carboxyl level of 92 to 100 percent, expressed as polyanhydruglucuronic acid content. The testing involves washing in aqueous alcohol, drying, dissolving in excess standard alkali, and then back titrating with standard acid.

The shredded material is then substantially freed of excess nitrogen dioxide by means of a warm stream of dry air. This is followed by soaking in aqueous alcohol containing about 5 percent oxalic acid for 15 to 30 minutes. The carbonates, nitrites and nitrates of calcium are thus converted to calcium oxalate particles which are mainly interspersed among the carbohydrate fibers. In this form the calcium oxalate contributes to the ash but not to the glow sustenance.

EXAMPLE 2

The content of nitrite and nitrate ester byproducts of the nitrogen dioxide reaction is reduced by hydrolysis during this soaking and by discarding the solution afterwards, the nitrate anions can be removed. It is possible at this point to conduct an extraction by soaking in an organic solvent such as acetone to remove undesirable odor producing materials which become removable as a result of the nitrogen dioxide process. An aqueous alcohol solution of a soluble calcium salt such as the chloride, nitrate or acetate is then made and the wet shreds are then soaked therein for 10 to 20 minutes. A sample taken out, dried and ashed will show a considerable increase in ash. The amount of ash uptake can be controlled with considerable accuracy by controlling the exposure period and the temperature and concentration of the calcium solution, and also, its alcohol content.

The material is then rinsed off with alcohol, and immersed in an aqueous alcohol solution of oxalic acid. The oxalic acid which diffuses into the fibers of the material forms insoluble calcium oxalate inside the fibers. A small amount of loss of calcium may occur due to diffusion of calcium ions from the inside of the fibers to the outside, but this can be controlled by the oxalic acid strength, the alcohol strength, and the temperature of the reaction. After a treatment of an hour or so, the material is removed and washed thoroughly to remove all soluble materials. The process may be repeated several times to build up the desired level of internal ash.

EXAMPLE 3

An alternative method of applying internal ash, especially suitable for the more soluble mineral salts such as the lactates and glycolates, is to absorb calcium salt into the material as described above. This will form the calcium salt of the oxidized cellulose. To avoid excessive embrittlement, it is preferable to limit such absorption to about half of the stoichiometric limit. The material can then be soaked in water to remove the liberated anion that was previously associated with the calcium. The required anion in the form of its free acid can then be added in the correct stoichiometric amount by dissolving it in just enough water or other volatile solvent to moisten and swell the material without making it wet. If the material is then dried, the required mineral salt will then be dispersed inside the material.

By applying anions and cations in sequence, so that they interact inside the fibers of the material, a level of internal ash can be attained which is sufficient to prevent the pyrolytic coagulative liquefaction which would otherwise interrupt the required smoldering process.

EXAMPLE 4

Other variants in this processing have been found effective. An alternative method utilizes our observation that in cold solutions, the precipitations of calcium and magnesium oxalate is a sufficiently slow process that the reagents can be admixed and then applied to the smoking material. Furthermore, such mineralization may be effected prior to the nitrogen dioxide oxidation process, where we have found it beneficial in reducing shrinkage and distortion. Mixtures of mineral salts can be incorporated in this fashion, for the control of ash properties such as whiteness, coherence, volume, porosity, thermal conductivity, and high temperature volume-transition phenomena.

EXAMPLES 5--12

In the foregoing examples, the calcium salt, such as the calcium nitrate or acetate of example 2, or the calcium salt of example 3, is replaced by a corresponding amount of a magnesium, lithium, barium, strontium, aluminum, titanium or silicon salt to produce the corresponding magnesium oxalate, barium oxalate, strontium oxalate, titanium oxalate and the like mineralizing agents, with treatments being repeated until a mineral content within the range of 5 to 45 percent by weight is obtained.

EXAMPLES 13--17

Examples 1--12 are repeated except that instead of oxalic acid, use is made of a corresponding solution of glycolic, diglycolic lactic, pivalic or tannic acid as the anion to produce the corresponding calcium, magnesium, barium, lithium, strontium, aluminum or titanium oxalate, glycolate, diglycolate, lactate, pivalate or tannate with the treatments being repeated until the salts are present in an amount within the range of 5 to 45 percent by weight or sufficient to produce an ash of 15 to 25 percent by weight.

The shredded material in its properly mineralized form can be used for pipe smoking or for compositions embodying a cigarette type of construction.

For proper burning, it is desirable to apply potassium oxalate or potassium hydrogen oxalate in the range of 0.5 to 1.5 percent. The amount is chosen to compensate for effects due to the dimensions and texture and packing density of the combustible material or to other applied substances.

As noted, it is also desirable to apply a small amount, e.g. up to 0.5 percent, of free oxalic, glycolic, or similar non-odor-producing acid, or generator thereof, to ensure the aforementioned fixing of the metallic cations.

Other materials can be chosen for control of odor and other parameters such as resiliency, preservation, and smoke. These include catalysts such as copper salts, amine generators such as ammonium salts and amides, odor masks such as menthol, glycols, esters, lactones, and formaldehyde condensates. A flavor can be embodied, but we prefer to confine the flavor to the filter, in the case of cigarette-type smoking devices.

The instant invention is ideal when preparing a cigarette-shaped smoking device. The device can be made by cylindrically wrapping the shredded material with cigarette paper, or preferably with a paper treated in accordance with the instant invention, or better still, with a paper made from pulp thus treated. A cigarette filter can then be attached, such a filter being treated with an appropriate flavor, such as menthol. Individuals smoking the cigarette-type product will experience a clean taste, and the smoke inhaled will prove to be extremely mild. The side stream smoke will be virtually odorless, and in no respect, irritating.

The materials can be employed in the manufacture of products to be smoked in a pipe or for a cigar-type smoke. In the latter case, wrappings for the cigar-type smoke can also be formed from the material of this invention. Flavoring additives can be added directly to the material to provide a wide variety of products. It will be appreciated that a great deal of versatility is provided, and that substances such as nicotine can readily be added whereby more conventional smoking tastes and aromas can be simulated. Obviously, completely new characteristics will also be available.

Techniques have also been developed whereby the products of the invention can be given a tobacco-type color if desired. In this connection, coloring agents are obviously available for changing the color of the materials. It has been found, however, that such coloring agents generally contain chemicals which adversely affect the odors during burning and which may introduce dangerous contaminants.

The technique of this invention involves the heating of oxidized cellulose to form a substantially darkened material. When this material is dissolved in water, the water will acquire a color. If desired, some purification can be then effected by washing with organic solvent and precipitating sugars with alcohol. The smoking materials can then be soaked in this solution. The solution acts as a dye, and various shades can be achieved, depending upon concentration, time and temperature. The suitable shades of brown can thus be accomplished without incorporating any undesirable contaminants in the smoking materials.

It will be understood that various changes and modifications may be made in the above-described products and processes which provide the characteristics of this invention without departing from the spirit thereof, particularly as defined in the following claims.

* * * * *

Current U.S. Class:	131/359 ; 162/139; 162/158
Current International Class:	A24B 15/16 (20060101); A24B 15/00 (20060101); A24d 001/18 (); A24b 015/00 ()
Field of Search:	131/2,9,15,17,140,144 162/139,158