Smokable Product Of Oxidized Cellulosic Material

Abstract

A smokable product of oxidized cellulosic material formulated to include combustible carbon in an amount within the range of 2-50 percent by weight of the oxidized cellulosic material for the improvement in the smoking characteristics of the smoking product forward thereof. The combustible carbon particles are of approximate colloidal dimensions and increase the heat of combustion of the oxycellulose. Melting of the oxycellulose is minimized with the carbon additive. Further, the carbon particles may carry a volatile additive absorbent thereon and function as a filtration means downstream from the combustion area. The carbon particles may be secured to the oxycellulose by means of a soluble carbohydrate binder.

Parent Case Text

This is a continuation-in-part of our copending applications U.S. Pat. Ser. No. 595,622, filed Nov. 21, 1966, now U.S. Pat. No. 3,447,539 and entitled "Smoking Products," and U.S. Pat. Ser. No. 674,994, now abandoned, filed Oct. 12, 1967, and entitled "Smoking Products and Process for Making Such Products."

Description

This invention relates to a smokable product produced of oxidized cellulosic materials and to smoking products produced thereof.

As used herein, the term "smokable products" is meant to refer to and include filler material for use in cigarettes, cigars, pipe tobacco and the like, cigarette papers, wrappers and the like used in the preparation of cigars and cigarettes.

In the aforementioned copending applications, description is made of the preparation of a smokable product suitable for use in cigars and cigarettes and pipes wherein the smokable product is prepared of relatively pure cellulosic materials subjected to selective oxidization 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 oxycellulose. The oxidation reaction produced is further processed by removal of nitrogen oxides by vaporization and washing and by extraction with an organic solvent to remove undesirable impurities, such as oils, waxes, latexes and aromatics which have been released as a consequence of the treatment with nitrogen dioxide.

As further described in the aforementioned copending applications, the oxidized and cleansed oxycellulose is further processed by a reduction reaction with borohydride of an alkali or alkaline earth metal, such as sodium borohydride, for reduction of nitro compounds, quinones, ketones and aldehydes which otherwise might have a tendency to impart undesirable aroma and taste to the smoking product when burned, or to reduce stability thereof during storage.

The product, before or after reduction, can be subjected to additional oxidation with a dilute solution of peroxide to eliminate further groupings that contribute undesirable aroma or taste to the product. The need for such treatments naturally varies with the initial purity of the oxycellulose.

The refined oxycellulose is then formulated with mineralizing agents, such as oxalates, glycolates, diglycolates, lactates, pivatates or tannates of the alkaline earth metals, preferably in a manner to form such salts internally of the oxycellulose fibrils. As described, internal formation can be achieved by first forming the alkaline earth metal salt of the oxycellulose and then treating with a solution of the anion to precipitate the mineralizing salt in situ in the cellulosic material.

The treated oxycellulose can be further formulated to improve burning, glow and smoking characteristics by the use of potassium, rubidium or cesium salts, such as the oxalates as described in the aforementioned copending applications and in the copending application U.S. Pat. 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 from the product can be introduced, as by the use of fatty acids and the like, and suitable aroma can be achieved by the addition of volatilizable alkalizing material, such as ammonium oxalate, urea and the like.

It has been found that oxidized cellulosic material does not burn as vigorously as tobacco with the result that the smokable product often times experiences difficulty in maintaining full combustion. Such less vigorous burning may also tend to lend to thermal decomposition instead of combustion of the carbonaceous components with corresponding increase in tars and the like materials sought to be eliminated by the smokable product of this invention.

There is reason to believe that the deviation in combustion is attributable, at least in part, to the lower heat of combustion of oxidized cellulosic materials, as compared to cellulose or tobacco. The heat of combustion of cellulose is calculated to be about 4.2 kilocalories per gram, whereas the heat of combustion of fully oxidized cellulose is calculated to be about 3.2 kilocalories per gram.

Attempts have been made to increase the heat of combustion of the smoking product by decrease in the proportion of oxidized cellulosic material employed but the result has been the generation of undesirable oxygenated short chain materials which contribute undesirable odor and irritating taste during combustion.

Thus, it is an object of this invention to produce and to provide a method for producing a smokable product of oxidized cellulosic material which enjoys desirable vigorous burning characteristics during combustion whereby the smokable product is capable of the desired rate of combustion without generation of undesirable taste and odors, and it is a related object to produce and to provide a method for producing a smokable product of the type described which has improved characteristics for use as a smoking product from the standpoint of taste, odor and appearance as well as reduction in the amount of undesirable compounds released with the fumes and smoke inhaled from the smoking product.

We have found that the burning characteristics of the oxidized cellulosic material can be markedly improved and that the use of the oxidized cellulosic material, as a smokable product, is also improved by the formulation to include a substantial amount of combustible carbon in uniform distribution with the oxidized cellulosic material and preferably bonded thereto in the form of fine particles or powders of almost colloidal dimension. Benefits are derived when the carbon is present in the smokable product in an amount as little as 2 percent by weight of the oxidized cellulose up to an amount as great as 50 percent by weight of the oxidized cellulosic material. When an amount less than 2 percent by weight is employed, the carbon has negligible effect and when the carbon content exceeds the upper limit of 50 percent by weight of the oxidized cellulosic material, the carbon has deleterious effect in that it tends to muffle the combustion of the oxidized cellulose, with corresponding generation of the undesirable odor and taste. In the preferred practice of this invention, combustible carbon is employed in an amount within the range of 15-40 percent by weight of the oxidized cellulosic material.

As the combustible carbon, it is preferred to make use of various forms of activated carbon charcoal, burnt cork and the like, in finely divided or powder form or other forms of combustible carbon, preferably of the absorbent type, as used in the absorption of gases, liquids, vapors or fumes.

It will be recognized that such replacement of substantial amounts of oxidized cellulose with the carbon will operate proportionately to reduce the concentration of oxidized cellulosic material making up the smokable product, with corresponding reduction in volatile organics, such as aldehydes, acids, phenols, polycyclics and tars often generated during combustion of the oxidized cellulosic material. This, of course, constitutes a benefit derived from the presence of carbon over and above its beneficial effect on combustion or burning rate of the smokable product.

The presence of carbon in the smoking product presents a number of other beneficial effects, some of which were wholly unexpected. For example, carbon present within the amounts described contribute color to the smokable product thereby to increase its aesthetic value as well as ability to blend the smokable material with tobacco to provide a mixture characterized by reduced volatilizable byproducts from tobacco.

Most significant is the fact that the carbon particles are capable of functioning as absorbents to enable pretreatment with liquids desired to be formulated into the smoking product and to achieve uniform distribution of such liquids with the treated carbon particles. The latter operate to retain such liquids in the desired distribution in the smoking product for their most beneficial use. Thus, the carbon particles serve as a means for uniformly distributing small amounts of liquid ingredients and for retaining such liquids in uniform distribution throughout the smokable product.

Still more significant and somewhat surprising is the ability of the carbon particles, uniformly distributed throughout the smoking product, to extract volatile organic components from the smoke and fumes and to withhold such absorbed materials while even in the hot zone generated during combustion of the smoking product. Thus, extra pyrolysis is required with more complete combustion of the absorbed volatiles with the result that less of the organic volatiles are released during combustion of the smoking product. While in the nonburning portion of the smoking product, the carbon particles function as a filter which removes and holds volatile vapors and fumes otherwise inhaled.

Another surprising result of the presence of carbon is that it helps to stop the undesirable tendency of oxycellulose to melt and coalesce during its pyrolysis and then produce bad odors. In this respect, carbon acts like calcium oxalate and, to some extent, substitutes for inorganic minerals. This allows a less coherent ash to be formulated.

The carbon particles may be formulated into the cellulose system in various ways. If the carbon particles are pasted with the oxidized cellulose fibers, much of the carbon will absorb or adhere, depending upon the amount of swelling and stickiness of the fibers, which depends further upon the temperature and pH of the paste. Instead, the cellulosic fibers may be impregnated with an aqueous dispersion of the carbon particles containing a binder component, such as a small amount of soluble polyuronic acid obtained by boiling oxidized cellulose in water, pectin, demethylated pectin, and the like carbohydrate binder materials.

Having described the basic concepts of this invention, illustration will now be made of the practice of the invention by reference to the following example, which is given by way of illustration and not by way of limitation.

EXAMPLE I

A low ash, low lignin, high purity paper is oxidized by immersion in liquid NO.sub.2 at 20.degree. C. for 5 or 6 days until caustic soda titrations show that the carboxyl content has reached an asymptotic level, which can be taken as indicating close to 100 percent conversion of the methylol groups. The paper is then removed and the NO.sub.2 volatilized off by drying. The paper is then rinsed and treated with a 1 percent suspension of calcium carbonate, containing an amount of calcium sufficient when absorbed in the oxidized cellulose to give an ash level of 15 percent to the dried product. The absorption of the calcium becomes substantially complete in 20-30 minutes and the material is then removed, rinsed and immersed in a 1 percent solution of oxalic acid of sufficient volume to form the oxalate of the calcium in the oxidized cellulose. After 20-30 minutes, the material is removed, rinsed to remove excess acids, and passed through a wringer to remove free water. While the fibers are still swollen, the material is pasted with an aqueous slurry containing 50 percent of finely powdered activated charcoal. By using a quantity of charcoal about half that of the dry fibers, a mixture of about 35 percent charcoal 65 percent oxidized cellulose can be prepared. The slurry is formulated to contain 1 percent by weight low methoxyl pectin for adhesion and the moist pasted fibers are then dried in a stream of warm air at 50.degree. C. To obtain a good rate of burning, 1 percent of rubidium or cesium oxalate is incorporated in the oxidized cellulose and carbon mixture. Approximately 0.5 percent of ammonium oxalate is also added, to give an alkaline smoke such that moist pH paper held in the smoke indicates a pH of 8 to 9.

By way of modification, the mineralizing or ashing ingredient in the form of calcium oxalate, can be incorporated into the cellulosic material before oxidation with liquid nitrogen dioxide. In such event, the steps of treating the oxidized cellulose with calcium carbonate and oxalic acid can be dispensed with in the above example. It is desirable to make use of such mineralizing agents as calcium, magnesium, or the like alkaline earth metal oxalates in an amount within the range of 5-40 percent by weight of the smokable product or in an amount to give 5-25 percent ash in the smoked product.

Instead of lignin, in example I, use can be made of other cellulosic materials, such as purified cellulose pulp or paper, alpha-cellulose, wood pulp, flax, hemp, straw and cellulose components derived from plants, leaves, weeds and the like.

Oxidized cellulose, formulated in the manner described, and which include suitable ash, burning accelerators and smoke modifiers, can be used alone as a smoking product, or it can be used as a diluent with tobacco for the manufacture of cigarettes with reduced tars and improved smoking characteristics.

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.

Claims

We claim:

1. A substitute smoking product adapted to be employed as combustible filler either alone or in combination with tobacco, said product being a mixture consisting essentially of an oxidized cellulose material and an incorporation of fine, absorbent combustible carbon particles approximating colloidal dimensions, said combustible carbon particles being within the range of 2-50 percent by weight of the oxidized cellulose, said combustible carbon particles functioning during combustion of the mixture in smoking to increase the heat of combustion of the oxycellulose and preclude the melting thereof, act as an absorbent for introducing a volatile additive and/or for smoke filtration downstream from the zone of combustion.

2. A substitute smokable product as claimed in claim 1 in which the combustible carbon is present in an amount within the range of 15-40 percent by weight of the oxidized cellulosic material.

3. A substitute smokable product as claimed in claim 1 in which the carbon particles are bonded to the oxidized cellulosic material with a soluble carbohydrate.

4. The substitute smoking product of claim 1 in which the oxidized cellulose is stabilized by removal of the excess nitrogen dioxide subsequent to the oxidation of the cellulose.

5. The substitute smoking product of claim 1 in which the carbon particles are adhered to the oxycellulose by coating a suspension of the said particles in a water soluble binder onto the oxycellulose and then drying same.