US 3447539 A
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United States Patent 3,447,539 OXIDIZED CELLULOSE SMOKABLE PRODUCT INCLUDING ASHlN G INGREDIENT Theodore S. Briskin, Beverly Hills, and Geoffrey R. Ward,
Downey, Calif., assignors to Sutton Research Corporation, Santa Monica, Calif., a corporation of Delaware No Drawing. Filed Nov. 21, 1966, Ser. No. 595,622
Int. Cl. A24b 15/02, 15/06, 3/14 US. Cl. 131-2 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to smoking products. The invention is particularly concerned with the treatment of materials which are adapted to be included in a variety of different articles which may be considered completely new types of products suitable for smoking enjoyment or which may be considered as substitutes for more conventional smoking products.
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. This is the case even though various medical authorities have pointed out the possible adverse effect of said habits on the health.
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 as nicotine or known 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.
Smoking products developed as tobacco substitutes have had limited acceptance by the public. The ingredients employed have, in general, produced objectionable odors during smoking or have otherwise been unsatisfactory from the standpoint of enjoyment. To the best of applicants knowledge, there has been no suitable -arrangement developed for producing smoking products which are free from the possible adverse effects of tobacco and which are, at the same time, commercially acceptable. The use of filters has, in fact, been the only significant advance from the standpoint of reducing the said adverse effects which may possibly obtain in the use of conventional tobacco products. The best filters, however, tend to reduce the more desirable taste and aroma characteristics of cigarettes, and for that reason, there is still a high demand for unfiltered tobacco products and for products having less effective filters.
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 previous 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 a combustible tube, to supply warm gases which are drawn through a module, such as a filter, which may or may not release a flavor into the gas stream. Where the demand exists, such arrangements can also be used for the administration of vapors with medicinal or physiological properties. 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 fi'om the standpoint of odor and taste during burning, and which it is believed contains no significant amounts of dangerous or otherwise objectionable 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 without subjecting the smoker to the possible adverse effects of the more conventional tobacco products.
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.
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, barium and potassium. 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 condtions during burning, such as odors, or the ingredients may react with other ingredients during burning creating the undesirable characteristics. In any event, it has been found that the substitution of undesirable anions by oxalate anions in the smoking product materials will reduce, and in some cases substantially eliminate, undesirable aspects of the materials.
The oxalates can be incorporated into materials in amounts from about five 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 five 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 absorbs 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 are known to be injurious to health. :In developing this invention, it was found that in the absence of nicotine, the purity of 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, proteins and colors 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 smokers respiratory system.
In providing a product which is in keeping with the stated ideals and which is substantially free of such ingredients, while at the same time maintaining the preferred resiliency characteristics, it is preferrable 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 unastisfactory for smoking purposes, despite its current use in cigarette papers, because of the very irritating aldehydes and acids that it evolves. 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 of 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 Patent No. 702,918, issued Feb. 2, 1965.
It will be understood that the oxidation treatment can ben 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.
While this aspect of the invention contemplates the use of cellulose at oxidation levels of to percent, such materials, containing 90 to 100 percent oxidized material computed on a polyanhydroglucuronic acid basis, do not make satisfactory smoking materials when treated by the known techniques for incorporating the necessary ash.
When such material is treated with the conventional salts of calcium, magnesium and potassium, unpleasant burning odors are roduced which are recognizably char acteristic of each of these metal cations. Partly this is due to the very low level of other odors.
Secondly, if such material is treated with mineral materials of increasing particulate nature such that lesser ratios of mineral molecules are exposed to the pyrolyzing environment, thus reducing the odor problem, the material becomes unable to sustain the glow needed for a satisfactory smoking experience. Furthermore, it is apt to flare when first lit or when vigorously drawn.
Finally, although potassium nitrate is a well-known and widely used glow sustainer for tobacco and cellulose, it is without such effect in a polyanhydroglucuronic acid system of this degree of purity.
An important feature of this invention involves the finding that calcium oxalate, however, has an anion of sufiicient 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 five 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 salt, 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 cations 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 otherobjectionable 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 five percent by weight of the treated material.
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 to 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 resutls 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 eifects. We have found more specifically that the preferable materials include the oxalates, glycolates, diglycolates, 'lactates, pivalates and tannates of calcium, magnesium, lithium, potassium, 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 icellulose. Accordingly, a feature of the invention involves the incorporation of a small amount of potassium oxalate, or potassium hydrogen oxalate, in amounts up to five percent and preferably between /2 and 1 percent by weight.
The following description illustrates a typical process for the preparation of a smoking material in accordance with the instant invention.
A highly purified commercial gnade of Wood pulp is fabricated into a thin paper of a thickness comparable to commercial lcigarette paper, 15 to 25 percent calcium cabonate powder being incorporated as a filler. This paper is shreded into strands of about two millimeters width and immersed in approximately one hundred times its weight of liquid nitrogen dioxide maintained at 20 C. Immersion continues for about five to ten days, or until testing indicates a carboxyl level of 92 to 100 percent expressed as polyanhydroglucuronic 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 five 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 carbohydrades fibers. In this form the calcium oxalate contributes to the ash but not to the glow sustenance.
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 lean 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 ican 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 diifuses 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.
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 stoichio-metric 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.
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 sufliciently 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.
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 eifects 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., 0.5 percent, of free oxalic, glycolic, or similar nonodor-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 materials 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.
Obviously, the smoking materials described above are characterized by main stream and side stream properties which are ideal. The smoke produced during burning will be unobjectionable in that the material itself will not, it is believed, produce any undesirable odors and will subject the smoker to lower levels of undesirable smoke constituents as compared to that of conventional tobacco products.
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.
Although the invention provides products which are intended primarily for enjoyment, it will be appreciated that a significant advance is achieved due to the complete or virtual complete elimination of such possibly carcinogenic substances as benz pyrene and benzene compounds as well as deleterious compounds such as the alkaloids normally found in tobacco.
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.
That which is claimed is:
1. A process for the manufacture of smoking 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 smoking product in which the ashing ingredient is selected from the group consisting of calcium oxalate, magnesium oxalate and mixtures thereof and is present in an amount within the range of to 40 percent by Weight of the smoking 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 smoking product.
4. A process for the manufacture of smoking 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 calcium oxalate and magnesium oxalate 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.
5. A smokable product comprising a charge of oxidized celluose and an ashing ingredient incorporated therewith selected from the group consisting of calcium oxalate and magnesium oxalate and mixtures thereof, the said ashing ingredient constituting between 5 to percent by Weight of the smokable product.
References Cited UNITED STATES PATENTS OTHER REFERENCES Shmuk: (Text) The Chemistry and Technology of Tobacco, pb. by Pishchhpromizdat, Moscow 1953. trans- 20 lation by National Science Foundation, 1961, PST CAT N0. 96; pages 588, 589 and 611 cited.
Osol-Farrar: The Dispensatory of the U.S.A. 2nd edition (1955), pub. by Lippincott Co., Philadelphia, p. 226 cited.
MELVIN D. REIN, Primary Examiner.
US. Cl. X.R.