Process For The Production Of Tobacco Foils And Products Thereof

Abstract

In the process of producing tobacco foils comprising the steps of mixing a slurry of tobacco dust with a water-soluble binder to form a moldable slurry, forming a tobacco foil or film and drying said tobacco foil or film, the improvement which consists of using as said water-soluble binder, a water-soluble methylcellulose containing from 0.05 to 0.25 carboxymethyl groups and also containing from 1.4 to 2.1 methoxy groups per anhydro glucose unit in said methylcellulose.

Description

THE PRIOR ART

It is known to prepare tobacco foils or films, which serve as binders for cigars, small cigars or cigarillos, whereby tobacco dust is made into a paste with aqueous solutions of a high molecular weight film-forming substance to give a plastic mass and this mass is then shaped into a film and dried. Cellulose ethers such as methylcellulose or carboxymethylcellulose (German Pat. No. 872,176 and Swiss Pat. No. 228,204) have been found to be suitable as the film-forming substances.

The known processes have some disadvantages however. For example, water-soluble methylcellulose has the disadvantage of flocculating at elevated temperatures. For this reason the machines for producing tobacco foils cannot be run at elevated temperatures and the performance of these relatively expensive machines is thereby limited. If carboxymethylcellulose is used, higher temperatures may be used and, therefore, an improved machine performance is obtained but other disadvantages occur. The foils so made easily adhere to the carrier belt and the finished foils possess poor burning properties and also have had taste properties.

OBJECTS OF THE INVENTION

An object of the present invention is the development of a process for the production of tobacco foils from tobacco dust which overcomes the disadvantages of the prior art utilizing, as a binder, a water-soluble methylcellulose having carboxymethyl groups.

Another object of the invention is the development of a process of producing tobacco foils comprising the steps of mixing a slurry of tobacco dust with a water-soluble binder to form a moldable slurry, forming a tobacco foil or film and drying said tobacco foil or film, the improvement which consists of using as said water-soluble binder, a water-soluble methylcellulose containing from 0.05 to 0.25 carboxymethyl groups per anhydro glucose unit in said methylcellulose.

These and other objects of the invention will become more apparent as the description thereof proceed.

DESCRIPTION OF THE INVENTION

The above objects have been achieved and the drawbacks of the prior art have been overcome by the instant inventive process for the production of tobacco foils or films which comprises adding tobacco dust, or a paste or slurry thereof with water, to an aqueous solution of a water-soluble methylcellulose which contains 0.05 to 0.25 especially 0.1 to 0.2 carboxymethyl groups, per anhydro glucose unit in the molecule so as to form a plastic mass which is subsequently formed into a film or foil and dried.

Suitable water-soluble cellulose derivatives for the purpose of the invention are produced starting from methylcellulose which contains 1.4 to 2.1, especially 1.6 to 1.8, methoxy groups per anhydro glucose unit in the cellulose molecule. The viscosity of a 2 percent aqueous solution of the suitable known and commercial types of methylcellulose may vary within the wide limits and lies between 100 and 40,000 cp. at 20.degree. C. Preferred starting types of methylcellulose are those which possess a viscosity which lies between 500 and 3,000 cp.

The introduction of the carboxymethyl groups is simple. Thus the methylcellulose can be kneaded with concentrated caustic soda liquor and monochloroacetic acid neutralized wholly or partly with caustic soda liquor or soda, and heated in known way for some time at temperatures from 50.degree. to 80.degree. C. Further, the reaction can also be carried out using solvents such as ethanol, isopropanol, butanol or acetone. The quantity of monochloroacetic acid used depends upon the desired degree of substitution. The reaction proceeds almost quantitatively. Obviously bromoacetic acid can also be used instead of monochloroacetic acid.

In one embodiment according to the invention, the water-soluble film-forming methylcellulose is firstly dissolved in water. In this solution or in the gel, the tobacco dust, or suitably a tobacco dust made into a paste or slurry with water, is incorporated therein. The ratio of tobacco dust to film-forming methylcellulose should be such that 10 to 30 parts by weight of film-forming methylcellulose are used to 100 parts by weight of tobacco dust (on a dry basis).

In the aqueous mixture of the ratio of solids to water should be such that an easily shapable mass is present which, for example, by calendering, molding, casting, rolling or applying to a suitable smooth surface by means of a doctor knife, can be worked into a smooth foil or film. Easily workable masses should have a viscosity of say 10,000 to 50,000 cp., according to Brookfield, at 20.degree. C. The foils which can be produced according to the invention are then dried at temperatures between 80.degree. and 115.degree. C. The air which may be used for the drying is itself heated to a substantially higher temperature, say to 150.degree. to 220.degree. C. In the drying, it is preferable that the water is not removed in its entirety. A residual moisture of 5 percent to 35 percent is retained.

Further assistants may also be used during the operation of the process of the invention, such as agents for improving the wet strength. It is known that natural tanning materials may be used for this purpose, such as tannins or tannic acids of different origin or catechutannic acids, catechols, quercitannic acids or chestnut tannic acids, ellagic acid or similar compounds. For the improvement of the wet strength, however, divalent aldehydes, such as glyoxal, are preferably used.

Further, plasticizing substances or fillers are suitably added during the production of the tobacco foils. Suitable plasticizers are, for example, sugar syrup or polyhydric alcohols, such as ethyleneglycol, glycerine, sorbitol, diethyleneglycol. Suitable fillers are kaolin, bentonite, diatomaceous earths or finely divided silicic acid. If desired, tobacco fibers, cellulose fibers or glass fibers in small amounts may also be added.

The tobacco foils obtainable by the process according to the invention are marked by an improved tear resistance, which is also manifested in the increase of the breaking load and the tenacity. The improvement amounts to about 50 percent compared to the values which are obtained when utilizing a methylcellulose which has not treated as above in the process.

It could not have been expected that, by the introduction of the small amount of carboxymethyl groups, not only the flocculation point would be raised to over 100.degree. C., but also that a substantial improvement of the mechanical properties would occur. This improvement of the tear resistance also enables the machines for the production of the tobacco foils to be operated substantially more rapidly without tearing of the foils taking place.

The following specific embodiments are illustrative of the invention without, however, being deemed limitative.

EXAMPLE

Commercial methylcellulose (1.7 methoxy groups per anhydro glucose unit; viscosity of the 2 percent aqueous solution 1,300 cp. at 20.degree. C. according to Hoppler) was moistened with 0.2 mol of 50 percent caustic soda liquor (referred to anhydro glucose unit) and an amount of neutralized monochloroacetic acid such that 0.175 of monochloroacetic acid was present to one anhydro glucose unit. The mixture was stored for 20 hours at 60.degree. C.

Twelve grams of the melhylcellulose containing about 0.175 carboxymethyl groups per anhydro glucose unit, prepared as described above, were dispersed in 350 cc. of water together with 1.75 g. of magnesium oxide, 1.50 g. of potassium nitrate and 2.5 g. of an aqueous 40 percent glyoxal solution. The binder solution so prepared was allowed to stand at room temperature for 16 hours.

Seventy five and five tens grams of tobacco dust were dispersed in 150 cc. of water and the dispersion was thoroughly mixed with the above-prepared binder solution. The pH value was adjusted by 5 by addition of phosphoric acid. The finished pulp or slurry had a viscosity of 25,000 to 30,000 cp. according to Brookfield (20 r.p.m. at 20.degree. C.).

The tobacco pulp was applied to stainless polished steel sheet with a doctor knife of specified width of gap (0.6 mm.) and dried at 100.degree. C.

The dried foil has a moisture content of 13.65 percent and a weight of 94.25 g./m..sup.2. The tear resistance was 0.412 kp./mm..sup.2, the breaking load was 0.757 kp. and the tenacity amounted to 626 m. (German Industrial Standard 53 112).

COMPARATIVE EXPERIMENT

The procedure was as described above, but a methylcellulose was used which had not been treated with monochloroacetic acid.

In this case a foil was obtained with a moisture content of 13.6 percent and a weight of 90.64 g./m..sup.2. The tear resistance amounted to 0.248 2, 2, the breaking load was kp./mm..sup. kp., and the tenacity was 309 m.

The preceding specific embodiment is illustrative of the practice of the invention. It is to be understood, however, that other expedients known to those skilled in the art may be employed without departing from the spirit of the invention.

Claims

We claim:

1. In the process of producing tobacco foils comprising the steps of mixing a slurry of tobacco dust with a water-soluble binder to a moldable slurry, forming a tobacco foil or film drying said tobacco foil or film, the improvement which consists of using as said water-soluble binder, a water-soluble methylcellulose containing from 0.05 to 0.25 carboxymethyl groups per anhydro glucose unit and from 1.4 to 2.1 methoxy groups per anhydro glucose unit in said methylcellulose.

2. The process of claim 1 wherein said water-soluble methylcellulose contains from 0.1 to 0.2 carboxymethyl groups per anhydro glucose unit and from 1.6 to 1.8 methoxy groups per anhydro glucose unit.

3. The process of claim 1 wherein from 10 to 30 parts by weight of said water soluble methylcellulose containing 0.05 to 0.25 carboxymethly groups per anhydro glucose unit are employed for 100 parts by weight of tobacco dust.

4. The process of claim 1 wherein said water-soluble methylcellulose has a viscosity in a 2 percent aqueous solution at 20.degree. C. of between 100 and 40,000 cp.

5. The process of claim 1 wherein said moldable slurry has a Brookfield viscosity at 20.degree. C. of between 10,000 to 50,000 cp.

6. The process of claim 1 wherein said formed tobacco foil or film is dried at temperatures between 80.degree. C. and 115 C.

7. The process of claim 1 wherein said water-soluble binder contains a divalent aldehyde for improving the wet strength of the tobacco foil or film.

8. The process of claim 1 wherein said moldable slurry contains fillers and plasticizing components.

9. The tobacco foil produced by the process of claim 1.