US3608559A - Process of introducing ashing ingredients into oxidized cellulose material intended as smoking product and product obtained thereby - Google Patents

Abstract

A method of making a smoking product formed of oxidized cellulosic material is disclosed in which incorporation of ash forming components is effected in the form of mineralizing agents preferably developed in situ internally of the oxidized cellulosic fibers by treatment first with a calcium compound in aqueous medium and then with oxalic acid to form insoluble calcium oxalate in situ or by treatment of the cellulosic materials with the freshly mixed components which remain soluble in admixture for a length of time sufficient for internal absorption into the oxidized cellulosic system.

Description

United States Patent [72] Inventors Theodore S. Brlskin;

Geoiirey R. Ward, both of Beverly Hills,

Calif.

2 l 1 Appl. No. 745,370

[22] Filed July 17, 1968 [45] Patented Sept. 28, 1971 I73] Aimignee Sutton Research Corporation Los Angelea, Calli.

Continuation-impart 01 application Ser. No. 595,622, Nov. 21, 1966, Patent No. 3,447,539, and a continuation-impart 01 674,994, Oct. 12, 1967, now abandoned.

[54] PROCESS OF INTRODUCING ASIIING INGREDIENTS INTO OXIDIZED CELLULOSE MATERIAL INTENDED AS SMOKING PRODUCT AND PRODUCT OBTAINED THEREBY 23 Claims, No Drawings [51] Int. Cl ...A24b 15/00 [50] FieldoiSeai-ch 131/ Primary Examiner-Melvin D. Rein Attorney-McDougall, Hersh, Scott & Ladd ABSTRACT: A method of making a smoking product formed of oxidized cellulosic material is disclosed in which incorporation of ash forming components is effected in the form of mineralizing agents preferably developed in situ internally of the oxidized cellulosic fibers by treatment first with a calcium compound in aqueous medium and then with oxalic acid to form insoluble calcium oxalate in situ or by treatment of the cellulosic materials with the freshly mixed components which remain soluble in admixture for a length of time sufi'icient for internal absorption into the oxidized cellulosic system.

PROCESS OF INTRODUCING ASlllING INGREDIENTS INTO OXIDIZIED CELLULOSE MATERIAL INTENDED AS SMOKING PRODUCT AND PRODUCT OBTAINED THEREBY This is a continuation-impart of our copending application Ser. No. 595,622, filed Nov. 21, 1966, now US. Pat. No. 3,447,539, and entitled Oxidized Cellulose Smokable Product including Ashing Ingredient, and Ser. No. 674,994,

filed Oct. 12, 1967, now abandoned, and entitled Smoking Products and Process for Making Such Products.

' As used herein, the term smoking products is meant to refer to and to include filler material embodied in cigarettes,

cigars and for use with pipes and the like, and mixtures thereof with various proportions of tobacco and including cigarette papers and wrappers used in the preparation of such cigars and cigarettes, and it includes cigarettes, cigars and the like products manufactured with such filler materials and wrappers.

In the aforementioned copending applications, description is made of the preparation of a smoking product suitable for use in cigarettes, cigars or with pipes wherein the smoking product is prepared of relatively pure cellulosic materials subjected to selective oxidation with liquid nitrogen dioxide to convert preferably more than 90 percent of the methylol groups in the cellulosic molecule to yield a product which can be referred to as an oxycellulose or polyuronic acid. The oxidation reaction product is further processed by removal of liquid nitrogen dioxide by vaporization and preferably by washing the oxidized cellulosic product with water and/or alcohol and/or acetone or other solvent for removal of solubilized foreign material, including oils, waxes, latices and the like, which contribute undesirably to the taste and aroma when used as a smoking product in accordance with the practice of this invention.

As further described in the aforementioned copending applications, the oxidized and cleansed cellulosic derivative is further processed by a reduction reaction with borohydrides of an alkali or alkaline earth metal such as sodium or lithium borohydride for reduction of such nitrogen compounds, quinones, ketones, aldehydes and unsaturates as otherwise have a tendency to impart undesirable aroma and taste as the smoking product is burned. The product before or after reduction can be subjected to additional oxidation with a dilute peroxide solution as a means for eliminating further groupings which impart undesirable aroma or taste to the product.

The resulting smoking product is then formulated with mineralizing agents such as oxalates, glycolates, diglycolates, lactates, pivalates or tannates of such metals as calcium, magnesium, lithium, potassium, barium or strontium, preferably introduced to form the salt internally in the cellulosic derivative for purposes of providing desired ashing characteristics. instead of forming the described salts internally in the cellulosic derivative, beneficial characteristics can be achieved by external application of such mineralizing agents. As described, the desired internal introduction is achieved by first wetting the cellulosic derivative with metal cation in dilute solution for absorption into the cellulosic derivative followed by exposure to the acid anion in solution to precipitate the metal salt in situ in the cellulosic material.

The treated cellulosic derivatives can be further processed to improve the burning, glow and smoking characteristics by the formulation to include a potassium salt, such as potassium oxalate or by the addition of rubidium or cesium in the form of compounds thereof in amounts within the range of 0.1 to percent by weight but preferably less than 1 percent by weight, as described in the copending application, Ser. No. 623,528, filed Mar. 16, 1967, and entitled Smoking Products and Process for their Manufacture. Smoke generators for improving the appearance of the smoke generated by the product can be introduced as by the introduction of dimethyl tartrate or various fatty acids, esters, ethers and the like and the aroma and pH characteristics can be achieved by the addition of volatilizable alkalyzing material such as ammonium oxalate and the like.

The resulting product is suitable for use as a smoking product alone or in admixture with tobacco to produce a smoking product having good taste, good aroma and good appearance.

As the cellulosic raw material, use can be made of various forms of cellulose, such as wood pulp, alpha-cellulose, flax, fibrous carbohydrates, seaweed carbohydrates, bamboo filaments, cotton filaments, hemp, straw, refined paper, rice paper, filamentous gums and even plants and plant leaves or weeds and the like fibrous or sheet materials from which noncarbohydrate components have been separated, all of which is hereinafter referred to as cellulosic material.

It is preferred to make use of a purified cellulosic material from which various of the sugars, proteins, chlorophylls, flavones, colors, lignins, oils, waxes, resins and latices have been removed since these contribute undesirable odors and tastes to the smoking product.

Purified cellulose is unsatisfactory for use as a smoking product from the standpoint of taste, aroma and burning characteristics. This is believed to stem from the acids and aldehydes that are evolved upon pyrolysis of the cellulose. It has been found that many of the defects of pure cellulose can be greatly alleviated by conversion of the methylol groups to carboxyl groups to produce a product which readily pyrolyzes with complete burning of the cellulosic molecule into water vapor, and oxidation products of carbon such as carbon dioxide and low molecular weight compounds which readily volatilize. Thus the object is to achieve selective oxidation of the cellulosic material to convert methylol groups, primarily the methylol groups containing the C carbon, to carboxyl groups, preferably with better than percent conversion. There is no objection to further oxidation beyond percent by conversion of secondary hydroxyl groups as on C, and C, to monoand diketo groups so long as cleavage does not occur.

It has been found that liquid nitrogen dioxide yields an oxidation reaction that has the desired selectivity and that complete wetting of the cellulosic materials can be achieved almost instantaneously with liquid nitrogen dioxide with the result that the oxidation reaction takes place substantially uniformly throughout the cross section of the cellulosic material and at a much more rapid rate whereby a more uniformly and more completely oxidized product is obtained in less time. Furthermore, liquid nitrogen dioxide, when used in the proportions most suitable for the practice of this invention, operates to quench and immediately dissipate heat generated by the exothermic reaction so as to avoid the formation of hot spots or nonuniforrnity in the reactions.

In our copending application, Ser. No. 745,221, filed July 16, 1968 now [15. Pat. No. 3,516,416, and entitled "A Smoking Product and Method of Preparation, description is made of the oxidation of a cellulosic material by suspension in liquid nitrogen dioxide in the ratio of 1 part by weight cellulosic material to 5 to 1,000 parts by weight liquid nitrogen dioxide and preferably 1 part by weight cellulosic material to 25 to 50 parts by weight of liquid nitrogen dioxide. The reaction therein is carried out at a temperature within the range of 15 to 65 C. and at an autogenous pressure when the reaction temperature exceeds 21 C. (the boiling point of nitrogen dioxide, N 0

In our copending application, Ser. No. 745,135, filed July 16, 1968, and entitled Preparation of Smoking Product of Cellulose Derivatives and Process," description is made of the selective oxidation of cellulosic material wherein the oxidation reaction, including reaction rate and the amount of conversion, is materially improved by formulation of the oxidation reaction medium to contain up to 8 percent by weight of water in the liquid nitrogen dioxide system and by carrying out the reaction temperatures above 15 C. and preferably within the range of 20 to 45 C., depending somewhat upon the amount of moisture present in the reaction medium, whereby the reaction medium is rendered relatively nonelectrically conductive so that the presence of water in the reaction medium will not result in attack or degradation of the cellulosic material to be oxidized and wherein the formulation to include aqueous medium in the reaction of liquid nitrogen dioxide operates also to adjust the specific gravity of the reaction medium in the direction towards the specific gravity of the cellulosic material whereby suspension of the cellulosic material in the reaction medium is easier to achieve and maintain. The result is a more rapid and uniform oxidation reaction of the cellulosic material to produce a better product at a more rapid rate.

In our copending application, Ser. No. 745,132 filed concurrently herewith and entitled Method for Preparation of Smoking Product with Selective Reduction following Selective Oxidation," now U.S. Pat. No. 3,478,751 description is made of the treatment of the oxidized cellulosic material to effect reduction of any nitro groups as well as quinone, ketone and aldehyde groups present in the oxidized cellulosic material or impurities entrained therewith, by treatment with an alkali metal or alkaline earth metal borohydride or nascent hydrogen at a pH within the range of 3 to 7 and at a temperature within the range of to 30 C., with the oxidized cellulosic material admised with one to 1,000 times its weight of an aqueous solution of the soluble borohydride present in a concentration within the range of 0.05 to percent by weight.

In the further copending application, Ser. No. 745,402, filed July 17, 1968, and entitled A Smoking Product of Cellulosic Material Subjected to a Nitrogen Dioxide Oxidation and a Mild Oxidation with Peroxide," description is made of the treatment of the oxidized cellulosic material with an alkali metal, alkaline earth metal, or hydrogen peroxide at a pH within the range of4 to 6.5 and at a temperature below 50 C. with a solution containing the peroxide in an amount within the range of 0.001 to 1 percent by weight.

This invention is addressed to the treatment of the oxidized cellulose, independent of its method of oxidation, and with or without the described borohydride or hydrogen reduction, and with or without the subsequent mild oxidation with peroxide, further to improve the use of the oxidized cellulosic material as smoking product.

It has been found that insufficient ash-forming ingredient in the smoking product results in a coalescence or coagulation of the pyrolyzing carbohydrates to form a melt of materials during the smoking process. The result is a coagulative anaerobic pyrolysis which tends to smother the fire to the extent that the cigar or pipe or cigarette soon becomes extinguished. Upon relighting, the smoking product gives a bad taste, at least during the initial puffs, and the smoking product again becomes extinguished after a very short time thereby to constitute a most undesirable and unacceptable product. Furthermore, this type of anaerobic pyrolysis produces undesirable muffied bonfire odors.

It is an object of this invention to produce and to provide a method for producing a smoking product of cellulosic material, and preferably oxidized cellulosic material, containing ashforming ingredients of a type and concentration to form an ash of sufficient coherence and porosity to enable the ash to build up on the end of the smoking product without interfering with or blocking access of air to the burning area thereby to enable the desired burning rate to be maintained; which does not introduce undesirable taste or odor to the smoking product or the product when smoked; which does not effect thermal breakdown of the oxidized cellulosic material into ketone or aldehyde components which lend an undesirable odor or taste when burned; in which the ashing components are present in an amount that does not undesirably interfere with the burning rate or pleasure derived from the smoking product, and which gives the desired appearance and aesthetic values as derived from currently used tobacco, and especially to pro vide a reticulum adequate to absorb molten oxycellulose so that it does not coagulate into an anaerobically pyrolyzing tarry. mass.

Attempts have been made to employ inertinorganic sub stances, such as talc, perlite, calcined alumina, titanium dioxide and the like fillers as mineralizing agents for ashing purposes but these have not proven to be sufficiently successful,

when used alone, for various reasons including the inability to hold the ash and their tendency to coat around the organic material and encourage anaerobic pyrolysis with consequent smothered bonfire odors.

As described in the aforementioned copending parent applications, the desired ashing characteristics are provided in a smoking product formulated of cellulosic material, in accordance with the preferred practice of this invention, by formulation of the cellulosic smoking product with calcium or magnesium oxalate. The calcium and magnesium oxalates have greater thermal stability than the oxidized cellulosic material whereby the latter is burned off first during use of the smoking product and the calcium or magnesium oxalate, upon combustion of the oxidized cellulosic material, breaks down into calcium or magnesium oxides and carbonates which remain in the ash and carbon monoxide and carbon dioxide which go off with the smoke. The ash that remains is porous with sufficient coherence to be sustained on the burned end of a cigar or pipe or cigarette until flicked off.

While the invention will be described with reference to the use of calcium oxalate as the mineralizing or ashing component, it will be understood that instead of calcium oxalate use can be made of equivalent amounts of other salts such as are formed of a cation selected from the group consisting of alkali and alkaline earth metals, and preferably calcium and magnesium, and an anion selected from the group consisting of glycolic acid, diglycolic acid or lactic acid, and preferably oxalic acid, tannic acid or pivalic acid. The preferred ashing component is calcium oxalate and/or magnesium oxalate.

Improvement in the characteristics of the ash left by the burned smoking product is achieved when calcium oxalate is present in uniform distribution in the cellulosic smoking product in an amount as little as 1 percent by weight but it is preferred to make use of cellulosic material containing calcium oxalate and/or magnesium oxalate sufficient to give an ash of 15 to 30 percent by weight, calculated on the basis of calcium carbonate ash (40 parts by weight of calcium oxalate being approximately equivalent to 30 parts by weight of calcium carbonate). When more than 30 percent by weight ash level is present in the cellulosic material, the dilution of the cellulosic material becomes excessive so that the desired burning or smoking characteristics are difficult to achieve and it is also difficult to maintain the desired burning rate, and smothered odors begin to appear.

This application will be addressed to the modification wherein the cellulosic material is in the form of an oxidized cellulose at the time that the calcium oxalate and the like ashing component is incorporated into the smoking product. Such oxidized cellulosic material is a polyuronic acid constituted with a number of uronic groups such as anhydroglucuronic acid and anhydrogalactouronic acid, formed by conversion of methylol groups during the oxidation, and including the keto, diketo and related oxidation derivatives of the uronic acids.

It is the preferred practice of this invention to disperse the calcium oxalate internally within the fibers of the oxidized cellulosic material, although limited benefit can be obtained by the incorporation of calcium oxalate on the outside of the fibers or interstitially between the individual fibers. The distinction between internal and interstitial ash is an important one in processing and evaluation studies.

It appears, at present, that the use of calcium or magnesium oxalate is preferable since such oxalates, when incorporated within the fibers of the oxidized cellulosic material, are effective ash-producing agents. Moreover, theoxalates do not have the side effects of producing undesirable odors or of affecting the combustion rate of the material. it isbelieved that the oxalate anion is sufficiently refractory to maintain the calcium or magnesium as an oxalate while the oxidized cellulose is undergoing pyrolysis. This prevents the immediate formation of calcium or magnesium polyuronate and the corresponding pyrolytic odor' effects, reminiscent of ketones as produced by the pyrolysis of organic calcium salts. V

The aforesaid oxalates are insoluble and therefore the problem is to provide means whereby such normally insoluble ash-forming materials may be incorporated into the fibers of the oxidized cellulose. We have discovered a number of ways in which such mineralizing materials can be introduced into the fibers of the oxidized cellulosic material.

For example, if oxidized cellulose is the starting product, incorporating of the oxalate into the fibers can be achieved by first soaking the oxidized cellulose in a soluble mineral salt solution such as a dilute solution of calcium acetate. The cation readily incorporates itself into the oxidized cellulosic material to fonn the calcium salt of the oxidized cellulose which can be described as a calcium polyuronate. This treatment is followed by a soaking in a solution of oxalic acid whereby the calcium polyuronate reacts with the oxalic acid which regenerates the polyuronic acid and produces insoluble calcium oxalate as an internal component inside the oxidized cellulosic fibers. Acetic acid which is formed during the replacement reaction and any excess oxalic acid is removed from the treated cellulosic material by means of a water wash.

The calcium can be introduced in the dissolved state in an aqueous medium in which the oxidized cellulosic material is suspended and wherein the calcium ion is made available for reaction to form calcium polyuronate. For this purpose, the calcium may be introduced as a water soluble salt such as calcium acetate, calcium chloride, calcium glucuronate, calcium bicarbonate, or the like, but it is preferred to make the calcium available for reaction with the oxidized cellulosic material by means of dissolving chalk or lime (slaked lime or preferably quicklime) in an acidic aqueous medium into which the oxidized cellulosic material is introduced to take up calcium to form calcium polyuronate. Thereafter oxalic acid is added whereby the oxalic acid which diffuses into the fiber is taken up by the calcium to fonn the calcium oxalate in situ within the cellulosic fiber, and thus to regenerate the oxidized cellulosic material in its original acidic condition.

When use is made of lime as the source of calcium, the acidic aqueous medium to which the calcium is added can be formulated from an organic or inorganic acid, such as acetic acid, nitric acid, hydrochloric acid, glucuronic acid and the like, with the acid present in an amount to provide an acidic solution having a pH less than 7 and preferably a pH within the range of 4 to 5. With hydrochloric acid or with acetic acid, the desired level can be obtained with the acid present in the aqueous medium in an amount within the range of 0.1 to 2 percent by weight.

The pH of the solution into which the oxidized cellulose is introduced should not exceed 6.5, otherwise the oxidized cellulosic material will tend to dissolve therein. As a result, lime should not be added in an amount which will operate to raise the pH above 6.5 and it is preferred to add lime in an amount to raise the pH of the acidic aqueous medium to within the range of 4 to 6, and preferably about 5. For this purpose, lime can be added in an amount within the range of 0.01 to 4 percent by weight and preferably in an amount within the range of 0.01 to 1 percent by weight and still more preferably in an amount within the range of 0.02 to 0.05 percent by weight. Calcium oxide readily dissolves in the acidic aqueous medium to form the corresponding calcium salt. The addition of lime will operate to raise the pH of the solution. To avoid localized effects, it is preferred to conduct the calcium replenishment in a portion of the liquid separate from the portion containing the oxidized cellulose.

The oxidized cellulosic material, after taking up a suitable quantity of calcium ion, is then reacted with at least a stoichiometric amount of oxalic acid in solution in aqueous medium at a pH within the range of 2 to 7 and preferably within the range of 3 to 5. Calcium is taken from the calcium polyuronate to form the corresponding calcium oxalate in situ in the oxidized cellulosic fibers. Calcium oxalate is comparatively stable by comparison with the oxidized cellulosic material so that it' will remain while the cellulosic material is being pyrolyzed during smoking of the smoking product.

The reaction to form the calcium oxalate is not critically dependent upon temperature. However, it is preferred to carry out the described reaction at a temperature within the range of to 40 C. with a reaction time of to 10 minutes. Longer times can be used but will be unnecessary.

When in the preferred practice of the invention, use is made of a treating composition containing lime or the corresponding calcium salts in low amounts, the amount of calcium oxalate formed in situ in the oxidized cellulosic material will be insufficient to provide the preferred to percent by weight ash level in a single treatment. As a result, in the preferred practice of this invention, the cycle of treatment is repeated a number of times to build up the concentration of calcium oxalate to the desired level in the smoking product. By operating in this way, and avoid too much calcium polyuronate formation at any one time, it is possible to minimize damage to the fiber strength from distortion and embrittlement.

We have found that calcium oxalate and the like mineralizing agents can be introduced into the oxidized cellulosic fibers by application of a freshly prepared mixture of oxalic acid and calcium salt solutions. It appears that calcium oxalate remains in the dissolved state for a sufficient length of time to achieve substantial impregnation or penetration of the oxidized cellulosic material before it precipitates in its insoluble fonn. It is believed that the calcium ions are sufficiently hydrated initially to form a soluble hydrated calcium oxalate which becomes insoluble as the water of hydration separates out. The rate of this dehydration decreases with temperature so that it is preferred to work at lower temperatures when practicing this concept. The same procedure will be found to be more readily applicable when working with magnesium salts for the formation of magnesium oxalate as an ashing component in the smoking product. With magnesium, this aging effect is much more pronounced.

In practicing this phase of the invention for introduction of calcium and/or magnesium oxalate, use can be made of an aqueous system containing 1 to 15 percent by weight calcium acetate and l to 15 percent by weight oxalic acid dissolved separately in separate increments of aqueous medium and mixed immediately prior to or during application to the oxidized cellulosic material. Concentration of acids and salts higher than 15 percent by weight each should be avoided, otherwise the fibers of the oxidized cellulose may become damaged. Treatment to incorporate the calcium oxalate or magnesium oxalate can be made at temperatures up to C. but lower temperatures from room temperature down to 0 C. are preferred to provide greater margin in the application time before separation of the insolubilized oxalate salt occurs. The cellulosic material should preferably be dry so that it will absorb the impregnant solution more positively.

Application can be made by spraying the mixture onto. the dry oxidized cellulosic material with proper agitation for uniform distribution or the mixture can be added with oxidized cellulosic material into a mixer or homogenizer for uniform distribution. When this technique is employed for mineralizing the oxidized cellulosic material, the aqueous mixture can be directly admixed with the oxidized cellulosic material in amounts to provide the desired concentration of calcium oxalate. After the mixing, a sufficient aging period must be allowed for the insolubilization reaction to occur.

With either technique for incorporation of the mineralizing agent in the amounts desired, excess materials can be rinsed from the treated oxidized cellulosic material with water. The product is then dried.

With the internal mineralizing agent present in the smoking product in an amount within the range of 15 to 30 percent by weight (calculated as calcium carbonate), it is undesirable to effect complete drying, otherwise the resulting product will be characterized by excessive brittleness. Instead it is preferred to dry to within the range of 25 to 60 percent relative humidity and preferably within the range of 40 to percent relative humidity.

Beneficial results are secured when an acidic component, such as oxalic acid, is reintroduced into the treated oxidized cellulosic material in an amount to provide up to 0.5 percent by weight acid. Such free acid remains to take up residual calcium or other heavy metal ion remaining in the smoking product or released therein during subsequent treatment or aging or pyrolysis. It probably exists in the system as calcium hydrogen oxalate.

By way of modification, it has been found that a smoking product having the desired ashing and smoking characteristics can be secured when the calcium oxalate, magnesium oxalate, barium oxalate or strontium oxalate, or the corresponding pivalates or tannates are replaced in part by an inorganic filler, such as perlite, talc, titanium dioxide, alumina, or silica. However, it is undesirable to reduce the calcium oxalate and the like mineralizing agent to an amount less than percent by weight of the smoking product. Such inorganic diluents or agents can be admixed dry with the treated smoking product and blended for uniform distribution to provide a total ashing component which does not exceed 30 percent by weight of the smoking product.

Having described the basic concepts of this invention, examples will now be given by way of illustration, but not by way of limitation, of the invention.

EXAMPLE 1 Oxidized cellulose is introduced into a reaction vessel having a mixer with sufficient water therein to provide a convenient mobility of the slurry when stirred. Acetic acid is added to a level of about 2 percent by weight acetic acid. Lime is added in an amount to provide an ash level of about 5 percent when completely absorbed by the oxidized cellulose. The pH of the solution thus rises from 4 to about 5. As the calcium is taken up by the oxidized cellulose, the pH of the system will fall back to about 4. After 5 minutes at ambient temperature, oxalic acid is added in a stoichiometric amount and the pH of the system immediately drops to about 3. After 5 to minutes at ambient temperature and as the oxalic acid is absorbed into the fiber by the calcium to form calcium oxalate inside the fiber, the pH of the system will rise to about 4 again.

The cycle is repeated five more times to produce an oxidized cellulose containing enough internally dispersed calcium oxalate to give about to 24 percent ash when burnt.

After the final cycle, the treated oxidized cellulosic material is thoroughly washed with water containing about 25 percent by weight ethyl alcohol, to remove surplus oxalic acid, and the cleansed oxidized cellulosic material is dried to about 40 percent atmospheric relative humidity.

After drying, one part by weight of aqueous solution of oxalic acid dissolved in an amount corresponding to 0.25 percent by weight of the oxidized cellulosic material is reintroduced with mixing into two parts by weight of product which is again dried to about 40 to 50 percent atmospheric relative humidity.

EXAMPLE 2 Instead of treating the oxidized cellulose with lime dissolve in the acidic solution, the oxidized cellulose may be treated directly with an aqueous solution containing about 0.1 percent by weight calcium acetate followed by the introduction of oxalic acid and with further processing in the manner described in example 1.

EXAMPLE 3 Instead of treating the oxidized cellulosic material with lime solubilized in acidic aqueous medium, as in example I, or with calcium acetate in solution, as in example 2, the oxidized cellulosic material may be treated with the calcium oxide or calcium acetate of examples 1 or 2 substituted by magnesium, strontium or barium oxide or acetate, respectively, and in corresponding amounts. Instead of making use of oxalic acid to form the corresponding oxalate, the oxalic acid in examples 1 and 2 may be substituted by tannic acid to form the corresponding tannate as the ashing ingredient. The oxalic or other acid can be introduced in the form of its soluble salts such as sodium oxalate, ammonium oxalate, sodium tannate, and the like.

EXAMPLE 4 EXAMPLE 5 A 6 percent solution of calcium acetate is provided in one container and a 6 percent solution of oxalic acid is provided in another and the two solutions are rapidly mixed one with the other in a container for immediate spraying with mixing onto purified oxidized cellulose in amounts calculated to wet the material with its equal weight of liquid. Application is made while the materials are maintained at a temperature between 0 and 10 C. to provide an oxidized cellulosic material in which the calcium oxalate is formed in situ by reaction of the dissolved calcium acetate and oxalic acid inside the fiber. After aging the material for an hour to allow the process ro reach completion, the treated oxidized cellulosic material is then thoroughly washed with water to remove the water solubles including excess acid, and the resulting product is dried to an atmospheric relative humidity of about 40 to 50 percent. The ash level will be about 2 percent. It can be increased to the desired level by repeated treatments.

A 0.1 percent oxalic acid is reintroduced from aqueous solution with mixing into the dried cellulosic material for reaction to take up residual heavy metal ions present in the smoking product or subsequently released therein.

In example 5, the calcium acetate can be replaced with corresponding amounts of magnesium acetate, barium acetate, or strontium acetate. Alternatively, instead of the acetates, the alkaline earth salts of lactic or glycolic or glucuronic acid and be used. When magnesium is used, the precipitation reaction is very slow an a very long aging period is required, or the material can be dried, after spraying to complete the reaction before water washing is applied. Alternatively, water soluble ash generators such as calcium salts of glycolic, diglycolic, lactic or pivalic acid, can be applied by direct spraying if no subsequent aqueous rinsings are used.

The product of examples 1 to 5 will have smoking characteristics greatly improved over cellulosic material alone or the oxidized cellulosic material before treatment in the manner described. It may be preferred further to process the treated oxidized cellulosic material produced in accordance with the practice of examples 1 to 5 as by subjecting the materials to a selective reduction reaction with borohydride, as described in the aforementioned copending application and/or by the modification of the treating material to incorporate various agents such as agents for controlling glow and burning rate with the addition of potassium, rubidium or cesium salts, as described in the aforementioned parent applications, or the addition of agents for providing smoking neutralizing agents such as ammonia or amine salts, coloring agents and the like, as described in the aforementioned copending parent applications.

Beneficial ashing characteristics of limited utility can be achieved by external application of such mineralizing agents, as by the introduction of calcium oxalate or others of the described mineralizing agents from suspension in aqueous medium for uniform distribution with the cellulosic material or by dry admixture of the mineralizing agent with blending for uniform distribution throughout the smoking product but y it is the preferred concept of this invention to incorporate such mineralizing agents internally in the oxidized cellulosic smoking product.

it will be understood that changes may be made in the details of formulation and operation without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. In the preparation of a smoking product of cellulosic material, the steps of mineralizing the cellulosic material while in an oxidized state to provide ash forming ingredients in an amount to make up to 30 percent by weight of the smoking product comprising the steps of treating the oxidized cellulosic material with salt forming solutions containing a cation in the form of a heavy metal selected from the group consisting of calcium magnesium, barium, strontium and mixtures thereof, and an anion selected from the group consisting of oxalic, pivalic, tannic, glycolic, diglycolic and lactic acids to form the corresponding salt in combination with the oxidized cellulosic material, and then rinsing and drying the treated cellulosic material.

2. The process as claimed in claim 1 in which the oxidized cellulose is first treated with the cation in aqueous solution whereby the cation attaches to polyuronic acids of the oxidized cellulosic material to form a corresponding salt, and then with the anion in-aqueous solution for reaction with the cation to form the corresponding insoluble salt.

3. The process as claimed in claim 2 in which the aqueous solution containing the cation has a pH less than 6.5.

4. The process as claimed in claim 2 in which the aqueous solution containing the cation has a pH of 4 to 5.

5. The process as claimed in claim 2 in which the aqueous solution containing the anion has a pH within the range of 2 to 7.

6. The process as claimed in claim 2 in which the aqueous solution containing the anion has a pH within the range of 3 to 5.

7. The process as claimed in claim 2 in which the aqueous solution containing the cation is formed by mixing the oxide of the metal in aqueous medium with an acidic component to take the oxide into solution.

8. The process as claimed in claim 7 in which the cation is introduced as lime.

9. The process as claimed in claim 8 in which the lime is present in an amount within the range of 0.1 to 4.0 percent by weight.

10. The process as claimed in claim 8 in which the lime is present in an amount within the range of 0.01 to l percent by weight.

11. The process as claimed in claim 7 in which the acid solution contains 0.01 to 2.0 percent by weight of acid.

12. The process as claimed in claim 7 in which the acid is in the form of acetic acid.

13. The process as claimed in claim 1 in which the salt forming solution with which the oxidized cellulosic material is treated is formed of freshly mixed solutions of a water soluble salt of the cation and a water solution of the acid but in which the salt formed of the cation and anion remains in the dissolved state for a sufficient period of time to enable penetration of the oxidized cellulosic material before precipitation.

14. The process as claimed in claim 13 in which the cation is selected from the group consisting of calcium and magnesium and in which the anion is selected from the group consisting of oxalic, tannic and pivalic acid.

15. The process as claimed in claim 14 in which the cation is present in the solution in an amount within the range of l to 15 percent by weight and in which the anion is present in the solution in an amount within the range of l to 15 percent by weight.

16. The process as claimed in claim 13 in which the cellulosic material is treated with the solution at a temperature between ambient and 0 C.

17. The process as claimed in claim 1 in which the treated oxidized cellulosic material is dried to a relative humidity of 25 to 60 percent. l

18. The process as claimed in claim 1 in which the treated oxidized cellulosic material is dried to a relative humidity of 40 to 50 percent.

19. The process as claimed in claim 1 in which the treatment is repeated a number of times until the mineralizing salts are built up in the oxidized cellulosic material to a desired level within the range of 15 to 30 percent by cation- 20. The process as claimed in claim 1 which includes a a part of the mineralizing agent an inorganic filler selected from the group consisting of perlite, talc, titanium dioxide, alumina and silica in amounts to replace up to 5 percent by weight of the cation anion salt formed in situ in the oxidized cellulosic material.

21. The process as claimed in claim 1 which includes adding an aqueous solution of an acid to the treated oxidized cellulosic material in an amount to provide the oxidized cellulosic material with up to 0.5 percent by weight of the acid and in which the acid is selected from the group consisting of oxalic acid, pivalic acid and tannic acid, and in which the free acid remains to take up residual heavy metal ions remaining or released in the smoking product.

22. A smoking product produced by the method of claim 1 23. A smoking product produced by the method of claim 21.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 559 Dated September 28, 1971 Inventor(s) Theodore Br kln et al in the aboveidentified patent It is certified that error appears corrected as shown below:

and that said Letters Patent are hereby Column 8, line 30, change "1:0" to "to";

Column 8, line 44, change "and" to "can";

Column 10, line 32, change "cation" to "weight";

Column 10, line 33, change "a a" to "as a" Signed and sealed this llth day of April 1972.

(SEAL) Attest:

EDWARD.M.FLETCHER ,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents FORM PO-IOSO (10-69) USCOMM DC 503764369 u 5 GOVERNMENT PRINTING ornc: 1 I9l9 o-ass-su

Claims (22)

1. 2. The process as claimed in claim 1 in which the oxidized cellulose is first treated with the cation in aqueous solution whereby the cation attaches to polyuronic acids of the oxidized cellulosic material to form a corresponding salt, and then with the anion in aqueous solution for reaction with the cation to form the corresponding insoluble salt.
2. 3. The process as claimed in claim 2 in which the aqueous solution containing the cation has a pH less than 6.5.
3. 4. The process as claimed in claim 2 in which the aqueous solution containing the cation has a pH of 4 to 5.
4. 5. The process as claimed in claim 2 in which the aqueous solution containing the anion has a pH within the range of 2 to 7.
5. 6. The process as claimed in claim 2 in which the aqueous solution containing the anion has a pH within the range of 3 to 5.
6. 7. The process as claimed in claim 2 in which the aqueous solution containing the cation is formed by mixing the oxide of the metal in aqueous medium with an acidic component to take the oxide into solution.
7. 8. The process as claimed in claim 7 in which the cation is introduced as lime.
8. 9. The process as claimed in claim 8 in which the lime is present in an amount within the range of 0.1 to 4.0 percent by weight.
9. 10. The process as claimed in claim 8 in which the lime is present in an amount within the range of 0.01 to 1 percent by weight.
10. 11. The process as claimed in claim 7 in which the acid solution contains 0.01 to 2.0 percent by weight of acid.
11. 12. The process as claimed in claim 7 in which the acid is in the form of acetic acid.
12. 13. The process as claimed in claim 1 in which the salt forming solution with which the oxidized cellulosic material is treated is formed of freshly mixed solutions of a water soluble salt of the cation and a water solution of the acid but in which the salt formed of the cation and anion remains in the dissolved state for a sufficient period of time to enable penetration of the oxidized cellulosic material before precipitation.
13. 14. The process as claimed in claim 13 in which the cation is selected from the group consisting of calcium and magnesium and in which the anion is selected from the group consisting of oxalic, tannic and pivalic acid.
14. 15. The process as claimed in claim 14 in which the cation is present in the solution in an amount within the range of 1 to 15 percent by weight and in which the anion is present in the solution in an amount within the range of 1 to 15 percent by weight.
15. 16. The process as claimed in claim 13 in which the cellulosic material is treated with the solution at a temperature between ambient and 0* C.
16. 17. The process as claimed in claim 1 in which the treated oxidized cellulosic material is dried to a relative humidity of 25 to 60 percent.
17. 18. The process as claimed in claim 1 in which thE treated oxidized cellulosic material is dried to a relative humidity of 40 to 50 percent.
18. 19. The process as claimed in claim 1 in which the treatment is repeated a number of times until the mineralizing salts are built up in the oxidized cellulosic material to a desired level within the range of 15 to 30 percent by weight.
19. 20. The process as claimed in claim 1 which includes as a part of the mineralizing agent an inorganic filler selected from the group consisting of perlite, talc, titanium dioxide, alumina and silica in amounts to replace up to 5 percent by weight of the cation - anion salt formed in situ in the oxidized cellulosic material.
20. 21. The process as claimed in claim 1 which includes adding an aqueous solution of an acid to the treated oxidized cellulosic material in an amount to provide the oxidized cellulosic material with up to 0.5 percent by weight of the acid and in which the acid is selected from the group consisting of oxalic acid, pivalic acid and tannic acid, and in which the free acid remains to take up residual heavy metal ions remaining or released in the smoking product.
21. 22. A smoking product produced by the method of claim 1.
22. 23. A smoking product produced by the method of claim 21.