US 3529605 A
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ep 1970 'M. BERING E IR ETAL 3,529,605
PROCESS AND APPARATUS FOR PRODUCING SHAPED TOBACCO MATERIALS Filed March 14. 1967 FIG] I INVENTORS MONIQUE BERINGER PAUL' BUCHMANN BY W I ATTORNEYS United States Patent 3,529,605 PROCESS AND APPARATUS FOR PRODUCING SHAPED TOBACCO MATERIALS Monique Beringer, St.-Louis, France, and Paul Buchmann, Basel, Switzerland, assignors to Tamag Basel A.G. Filed Mar. 14, 1967, Ser. No. 623,046 Claims priority, application Switzerland, Mar. 16, 1966,
. 3,774/ 66; Mar. 10, 1967, 3,534/ 67 Int. Cl. A24b 3/14 US. Cl. 131'133 15 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for producing shaped tobacco materials, such as sheet-like, filamentous or strand-like tobacco materials, comprising mixing and finely grinding a tobacco material together with a liquid in a preferably continuously working mill and shaping the ground material in a conventional manner. The brinding mill contains a stirrer which comprises a shaft having rings arranged in spaced manner therealong in staggered relationship and which on being set into motion, coact with grinding balls within the mill housing to secure homogenization of the tobacco. The temperature required for obtaining the de sired adhesiveness of the mixture is adjusted by means of the frictional heat developed in the mill. A liquid is used having a determined pH value.
It is known that the particle size of tobacco or of the veins of tobacco leaves used to produce shaped tobacco materials exert a substantial influence not only on the strength of the shaped tobacco material, but also on the elasticity thereof. This is more particularly the case, if
shaped tobacco materials are to be produced either in the full absence or in the presence of only small quantities of binders.
Furthermore it is known to grind tobacco in either a wet or dried form in order to get colloidal particle sizes of the tobacco material, which is then suspended in water or in a solvent, whereupon large quantities of binding agents are added to the resultant suspension. Moreover, such tobacco suspensions can be extracted under heating and, if desired, under pressure. The extract thus obtained can be mixed with further tobacco fractions; in this latter case relatively small amounts of binding agents are added. However, all methods known up to now require several operation steps which are complicated and uneconomical.
The main object of the present invention is the production of shaped tobacco products, such as sheet-like filamentous or strand-like tobacco products and the like, preferably by using just one operation step without requiring a substantial supply of energy and without using expensive apparatus. On the contrary, the new method of the present invention can be carried out with a minimum of working capacity.
According to the new method of this invention a tobacco material is mixed with a liquid and finely ground with the said liquid in at least one operation step in a mill, which preferably works in a continuous way, the ground material being then converted in a conventional way into the desired form.
The temperature required to develop the desired adhesiveness of the tobacco material can be furnished by the frictional heat produced in the mill.
It has also been found that the pH value of the liquid to be used will, in general, depend on the kind and on the pH value of the tobacco material (tobacco for cigars or cigarettes) which is to be treated.
In some cases it may be desirable to use small amounts of various additives in order to improve for instance the flavour of the smoke or the water-in-solubility of the shaped tobacco product. In such cases the desired additives can be added to the liquid and/or to the tobacco before grinding the mixture. This procedure permits a continuous working manner and does not require any pH control of the tobacco slurry during the manufacturing process.
The liquid to be used has normally a pH value ranging from 4 to 10 inclusive. Preferably a pH value ranging from 6 to 10 inclusive and in some cases from 7.5 to 9 inclusive will give satisfactory results. The liquid itself can be water or an aqueous solution of an acid, a base or a salt. A suitable base or salt respectively may be ammonia or potassium hydrogen carbonate.
It has also been discovered that the properties of the shaped tobacco material, like its flavour or its colour, can be influenced by suitable selection of the pH value of the liquid depending upon the tobacco type (light or dark tobacco), the pretreatment, such as the drying degree or fermentation degree, and/or upon the pH value of the tobacco material used.
If desired, up to 3 percent by weight of a binding agent foreign to and not present in the tobacco material, like methyl cellulose, ethyl cellulose, sodium carboxy-methyl cellulose and the like, and/or up to 5 percent by weight of a softening agent, such as glycerol, polyethylene glycol and so on, can be added to the mixture of tobacco and liquid, before the said mixture is introduced into the mill. In some cases, also up to 2 percent by weight of a fibrous material, eg asbestos or the like, can be added. Any one of these substances can also be added to the tobacco slurry flowing out of the mill.
It is preferred to use as starting material coarsely comminuted tobacco. It has been observed that it is advantageous to grind the mixture consisting of tobacco and liquid in a mill of the kind disclosed in the following and shown on the drawing, until the mixture contains colloidal particle sizes. Generally the mixture is wet ground in the mill while homogenizing the mixture and heating the same to at most C. due to the frictional heat developed during the grinding operation. It is also possible to lower the temperature produced in the .mill by frictional heat by cooling the mill in a conventional manner to a temperature below or much below 100 C. The new method is most suitably carried out in one single step.
The warm tobacco slurry flowing out from the mill can be dried in a conventional manner in order to produce a shaped tobacco material.
The shaped tobacco material made according to the present invention can be used as tobacco for cigarettes, cigars and pipes, i.e. as cut tobacco, cover or outer leaves, and as substitute for cigarette paper.
The present invention will now be described in more detail in the following examples. However, the invention is not intended to be limited either to the following examples or to the drawing.
EXAMPLE 1 500 liters of water are introduced into a container and mixed with 100 grams of potassium hydrogen carbonate to adjust the pH to a value of about 8.5. After addition of 100 kg. of light tobacco (e.g. Virginia tobacco) the resultant suspension is introduced into a continuously working mill by means of a metering pump and wet ground until the desired particle size has been reached. After a short starting period the temperature of the mixture increases without any external heat to about 70 C. The grinding period is about 15 minutes. The still warm tobacco slurry flows out from the mill and is immediately dried and converted into the desired form.
3 EXAMPLE 2 600 liters of water are introduced into a container and the pH value is adjusted to about 8.0 by adding 50 ml. of a 25% ammonia solution. Then 100 kg. of dark tobacco (e.g. Java tobacco for cigars), 2% of glycerol (based on the weight of the tobacco material used), 1 kg. of citric acid and 1.5 kg. of sodium carboxymethyl cellulose are added to the solution. The mixture is introduced into a continuously working mill by means of a dosage pump, homogenized and heated without external heat, but merely by means of the frictional heat to the temper ature suitable for causing the solution to react with the tobacco material. The wet ground tobacco slurry running out from the mill is immediately dried and shaped.
A mill, which is particularly adapted for the performance of the new process and constitutes also an aspect of the present invention, will now be described With reference to the accompanying drawing in which FIG. 1 is a side elevation of the mill, the housing being shown in section and FIG. 2 is a sectional view along the line I--I of FIG. 1.
In a cylindrical housing 1 a stirring mechanism 2 is arranged, comprising a shaft 3 with a number of rings 4. The rings 4 are secured to the shaft 3 and disposed asymetrically, in spaced relationship, one upon the other. The shaft 3 may be driven by a motor 9. In the housing 1 an opening 5 is provided for the inlet of the material to be ground, which consists of a mixture of liquid and tobacco. A further opening 6 is provided for the outlet of the ground material, this opening being covered by a screen 7. The housing is filled with small balls 10, which may be made of metal or any other suitable material. In a duct 11 leading into the opening 5 a pump 12 is arranged.
The operation of the mill is as follows: By means of the pump 12 the mixture of liquid and tobacco is fed through the opening 5 into the housing 1, where it moves to the upper part of the housing, the shaft 3 rotating at high speed. When passing the housing 1, which contains the afore-mentioned balls the tobacco particles are very finely ground and, at the same time, intimately mixed. The resulting frictional heat is used to cause the desired reaction between the tobacco material and the liquid. The exceeding heat can be dissipated by transmission to a cooling fluid circulating in a cooling jacket 13 with inlet and outlet connections 14.
A mill as heretofore described is, for instance, the Molinex mill offered by Gebr. Netzsch, Selb, Germany, under the designations KE 5, 20, 50 and 100.
What we claim is:
1. In a single-step continuous method for producing a wet ground tobacco slurry from a mixture of coarsely comminuted tobacco and a member of the group consisting of Water and an aqueous solution, the improvement comprising continuously grinding said mixture in a ball mill filled with small grinding balls and having a stirring tool consisting of a shaft with rings asymetrically disposed therearound, whereby the temperature required for obtaining the desired homogenization and adhesiveness of said slurry is supplied solely by the friction created between said rings and said grinding balls.
2. A method according to claim 1 comprising the use of an aqueous solution having a determined pH value which is independent of the pH value of said slurry.
3. A method according to claim 1, comprising the use of an aqueous solution having a pH value which is dependent upon the type of the tobacco to be treated,
4. A method according to claim 1 comprising the use of an aqueous solution having a pH value ranging from 4 to 10 inclusive.
-5. A method according to claim 4, comprising the use of an aqueous solution having a pH value ranging from 7.5 to 9.
6. A method according to claim 1 wherein the aqueous solution is selected from the group consisting of an aqueous acid solution, an aqueous base solution and an aqueous salt solution.
7. A method according to claim 1 wherein said mixture of tobacco and aqueous solution also includes up to 3% by weight of a binding agent foreign to tobacco taken from a group consisting of methyl cellulose, ethyl cellulose and sodium carboxy-methyl cellulose and up to 5% by weight of a softening agent taken from a group consisting of glycerol and polyethylene glycol.
8. A method according to claim 1, wherein said mixture consisting of tobacco and aqueous solution also includes up to 2% by weight of a fibrous material.
9. A method according toclaim 1, comprising grinding the mixture consisting of tobacco and aqueous solution to a colloidal particle size.
10. A method according to claim 1 comprising lowering the temperature in the mill due to frictional heat, by cooling to a temperature below C.
11. A method according to claim '1 wherein said mixture remains in said mill for a time not exceeding 15 minutes.
12. A mill for use in the single-step continuous production of a Wet ground tobacco slurry from a mixture of coarsely comminuted tobacco and a member of the group consisting of water and an aqueous solution, said mill comprising a housing, said housing having an inlet opening for said tobacco and said water or aqueous solution and an outlet opening for said slurry, a stirrer within said housing consisting of a shaft having rings arranged therealong in a spaced manner and in staggered relationship against each other with respect to the center thereof, said housing being filled with grinding balls which are set into motion by said rings, whereby the temperature required for obtaining the desired homogenization and adhesiveness of said slurry is supplied solely by the friction created between said rings and said grinding balls.
13. A mill as claimed in claim 12 wherein said rings are staggered against each other in an asymmetric manner such that said stirrer does not produce any static imbalance.
14. A mill as claimed in claim 12 wherein said housing is surrounded by a cooling jacket provided with an inlet opening and an outlet opening for a cooling medium.
15. A mill as claimed in claim 12 wherein said inlet opening is arranged in the bottom part of said housing and said outlet opening is arranged in the upper part of said housing.
References Cited UNITED STATES PATENTS 328,300 10/1885 De Sussini 131-17 2,433,877 10/1941 Wells et al 13l140 X 2,707,472 5/1955 Jurgensen et al. 131140 X 3,115,882 12/1963 Domeck et al. 13l17 MELVIN D. REIN, Primary Examiner US. Cl. X.R. 131140