EP0443321B1 - Tobacco sheet and process and apparatus for its preparation - Google Patents

Abstract

A tobacco foil (10) made from tobacco particles, water, binders and moisture retention material has two sealed outer layers (14) relatively impervious to gas and a cavity type center structure (16). The internal surface (17) of the lens shaped cavities is torn, hairy and wrinkled. The foil has a high filling capacity.

Description

The invention relates to a tobacco film with increased filling power according to the preamble of claim 1 and a method according to the preamble of claim 10 and a device according to the preamble of claim 29 for producing such a tobacco film.

In the manufacture of tobacco foil pieces from tobacco dust, tobacco greens and the ribs of tobacco leaves, it is known to extrude a foamed product from these starting materials. The disadvantage here is the relatively high demand for binders, in particular starch, which can easily impair the taste, aroma and burning behavior of smokable articles.

US Pat. No. 3,098,492 and DE-OS 28 04 772 describe the extrusion of a film by means of a slot die; However, such a process is complex and expensive if one wanted to use it to produce a film which has a filling capacity comparable to that of tobacco, and also has a high tobacco content and low binder content. This would only be possible with nozzle gap widths <0.15 mm.

It plays a role that the filling capacity of the tobacco film depends crucially on the smallest possible thickness corresponding to a small die gap width of the extrusion die, which is why the entire tobacco starting material must be reliably ground with a maximum grain size. Excessively large tobacco particles in the raw mass of the tobacco starting material can easily clog such an extrusion nozzle, which is why complex control measures or extremely reliable and therefore complex grinding processes are necessary.

The production of a film by extrusion of the starting material using a slot die in a roll nip is also known from US Pat. No. 3,098,492, DE-OS 28 04 772 and GB Pat. No. 1,459,218. Here, too, there are the disadvantages mentioned above of the low filling capacity compared to sheet material. In addition, the rolls forming the gap can only run at a low peripheral speed when operated with a slot die, so that a high torque is required, which leads to great stress on the roll construction with a relatively low throughput. An increase in throughput can only be achieved by increasing the roll width; this in turn requires an extremely large slot die, a stable roll structure and a large roll thickness in order to minimize the deflection of the rolls. In addition, a multiple calender must generally be used because a single forming step is not sufficient to achieve the required thickness evenly.

In another known method (DE-OS 31 04 098, DE-PS 20 55 672, DE-PS 24 21 652, DE-PS 32 24 416 and GB-PS 1 459 218), tobacco films must be produced by means of rollers an extremely strong addition of water to the starting material can be made in the range of 30 to 50%, so that subsequent drying is required. This increases the necessary procedural effort. In addition, unwanted organic solvents are often used here, e.g. Methylene chloride. Finally, a multi-stage rolling mill or a calender is usually required here as well.

A method and a device for reprocessing tobacco is also known from DE-PS 33 39 247. Dust-like tobacco particles and / or tobacco flour with binders and optionally additives are processed to a plastifiable mixture which is extruded into individual, strand-like intermediate products. These strand-like intermediate products are then processed into pieces of film by forming a cylindrical strand from the plasticized mixture in an extruder into a thin-walled, continuously expanding hollow body and dividing it into thread-like, crimping intermediate products. The thread-like, crimped intermediate products are then separated into individual, crimped fiber pieces. The intermediate products have a relatively dense structure, which also differ in the additives from the quality characteristics of natural tobacco.

From DE-OS 38 04 461 a tobacco reconstitution process is known in which a mixture of tobacco particles, starch and binders is extruded with the addition of water to give a web-like extrudate, the Extrusion conditions and the recipe are such that when the extrudate leaves the outlet opening of the extruder nozzle it assumes a cross section which is larger than that of the outlet opening of the extruder nozzle, and the extrudate is stretched in its plastic phase in order to reduce its thickness dimensions, the stretching ratio being at least Is 1.5; the stretched extrudate is cut to give particles, each having a cellular structure and an integral skin. The stretching or stretching process is relatively complex. If the tobacco film is torn off, this leads to a loss of time and material during production. Another disadvantage is the high proportion of binder required, which leads to impaired taste and aroma.

DE-OS 38 04 459 discloses a tobacco reconstitution process in which a mixture of tobacco particles, starch and binder and water is fed to an extruder, the operating conditions and the recipe being such that the water escapes from the sheet-like extrudate by evaporation, to expand the extrudate. After cooling, the extrudate is cut into particle size. The particles, each of which has a cellular interior structure and a skin on two opposite sides, can be used as or in cigarette filling material.

A disadvantage of this tobacco reconstitution process, however, as already stated, is that large amounts of starch and binders are required, which leads to changes in the taste and aroma of the tobacco material.

DE 33 28 663 C2 discloses a filling material made of reconstituted tobacco material and a method for its production. Two separate sheets of film are glued together in places, with cavities forming between the two sheets of film glued together. This procedure is complex, fragile and only provides film material with a low filling capacity. In addition, the device for carrying out the known method is complex and complicated.

DE 31 47 846 C2 relates to a method or a tobacco material in which expansion is achieved by enlarging the cell structure of the tobacco by reducing the pressure and greatly increasing the temperature. However, such a method is only possible with natural tobacco material, while it is not suitable for reconstituted tobacco material, since no expandable cell structures are available here.

EP 0 198 718 A2 discloses a method in which a reconstituted tobacco material is expanded from tobacco waste during extrusion. The expansion is accomplished by a high extrusion temperature and an abrupt drop in pressure when leaving the extruder in connection with a sufficient film thickness and a proportion of binder of at least approx. 10%. This manufacturing process is obviously based on completely different principles and also results in a completely different product which, due to its high binder content, leaves much to be desired in terms of its taste, burning properties and the like.

A method for producing reconstituted tobacco material is also known from EP 0 046 018 A1. However, this method is based only on stiffening the material and fixing the stiffener. The reconstituted tobacco material is over-dried and then moistened again. As a result, the reconstituted tobacco material loses a large part of its flavors and becomes extremely critical in its handling, since it becomes extremely brittle and friable as it dries. This process also results in a product that leaves something to be desired.

DE 38 19 534 C1 describes a thin, compact tobacco product without air pockets, in which several strands of material are formed by extrusion, which are then rolled back together to form a single-layer material layer.

The object of the invention is to propose a film with increased filling power, the production and enjoyment of which do not give rise to the disadvantages of the prior art listed above, and to provide an apparatus and a method, in particular for producing such a tobacco film .

In particular, the invention has for its object to produce a film that leaves little or nothing to be desired in the factors of taste, aroma, color, ash and smoke properties, density, elasticity and fragility, so that their properties hardly differ from those of tobacco distinguish; in addition, a method and a device are to be made available with which it is possible to produce such a film in a simple manner.

This object is achieved for the film according to the invention, the method according to the invention and the device according to the invention by the features in the characteristics of the independent claims 1, 10 and 29.

Advantageous and expedient refinements or variants are defined by the features in the subclaims.

A raw mass of tobacco particles, water, binders and humectants is processed to the film according to the invention, which consists of two relatively gas-impermeable, in particular surface-sealed cover layers on the outer surfaces, the cover layers being connected to one another via a sponge-like structure which contains gas-filled bubbles; gas-filled cavities are formed between the cover layers, these cavities being equipped with a shaggy or furrowed and / or torn surface. The burning behavior of the tobacco film according to the invention is in some cases better than average tobacco.

The two relatively gas-impermeable, in particular surface-sealed, top layers make it possible, on the one hand, to generate an extraordinarily high expansion pressure within the tobacco film during the production process and, on the other hand, to maintain the resulting increase in fill force over very long periods of time.

In order to achieve the desired quality factors of taste, aroma and color, it is crucial that at least approximately 86% by weight, in particular 92% by weight, of tobacco particles are present in the raw material which is processed into the tobacco film according to the invention. In this way, the extremely cost-intensive tobacco can be processed almost waste-free into high-quality smokable articles.

In order to ensure the required elasticity and a strength of the tobacco film comparable to that of the natural leaf, it is advantageous to use a humectant of approximately 1 to approximately 6% by weight, in particular 2 to 5% by weight, of the tobacco film. %, so that the tobacco film can maintain a certain moisture content of approx. 10 to 14% (wet basis) after production and also over longer periods. If this residual moisture were too low, there would be no possibility of extensive further processing of the tobacco foil.

Regardless of the contribution of the cavities, the thickness of the film should be between approximately 0.1 mm and approximately 0.4 mm; In particular, film thicknesses between 0.2 and 0.3 mm are advantageous in order to ensure a contribution to the desired natural tobacco characteristics.

The binder should not contain more than a maximum of about 2% by weight of starch, so that no unfavorable changes in the taste and aroma of the film can occur.

It is not absolutely necessary to add starch to achieve the expansion effect according to the invention.

In order to give the tobacco film according to the invention the physical properties of natural tobacco material as far as possible, it is advantageous to use glycerol and / or 1,2-propylene glycol and / or sorbitol as humectants.

These advantages for the tobacco film can also be achieved in that the binder carboxymethyl cellulose carboxymethylated and / or hydroxyethylated and / or agar-agar and / or alginic acid and its sodium, potassium and / or calcium salts and / or tragacanth and / or Guar gum and / or pectin and / or locust bean gum and / or gum arabic contains.

The cavities that are created in the position of the tobacco film can in principle have almost any size, relative to the film size. As particularly advantageous with regard to a nature-identical burning behavior, the filling power, etc. Characteristics of burning tobacco, however, expansion of the cavities in the direction of the film thickness from approx. 0.1 mm to approx. 5 mm, in the direction of the film width from approx. 0.1 to approx. 10 mm, in particular from 1 to 5 mm, have been found.

To produce the tobacco film according to the invention with increased filling power, a raw material is prepared which consists of approx. 86 to 98% by weight of tobacco material, a proportion of humectants of approx. 1 to 6% by weight and a proportion of binder from about 1 to 8% by weight. This raw mass is mixed with a water content of approximately at least 20%, in particular 20 to 40%, preferably 30% (all wet basis). The raw mass is extruded at a pressure of approx. 10 to approx. 200 bar, preferably between 50 and 100 bar, to the tobacco film, the extruder having a temperature profile of approx. 30 ° C. to approx. 160 ° C. A temperature profile of 40 ° C. to 140 ° C. is preferably present. The raw mass is pressed at the extruder outlet through a nozzle provided with outlet gaps, which creates the tobacco film. The tobacco film is then strongly heated from both sides in a relatively short time, as a result of which relatively gas-impermeable cover layers are formed. A further strong supply of heat evaporates the water located in the tobacco film in the position between the cover layers, which creates gas-filled cavities and bubbles.

Advantageously, the process step for producing the relatively gas-impermeable cover layers and the bubble-shaped cavities can be contracted into one process step, which greatly reduces both the process engineering and the outlay on equipment. Wide slot or ring nozzles can be used as the nozzle tool.

If an annular nozzle is used as the nozzle, a continuous tobacco film tube can be produced, which is advantageously provided with a plurality of cutting knives at the annular nozzle gap, as a result of which the tobacco film is cut into longitudinal strips, which are preferably in the form of endless belts, in particular with a width of approximately 3 up to approx. 5 cm from the nozzle mouth emerge. A tobacco film prepared in this way can be processed particularly effectively and without excessive outlay on equipment. In order to largely exclude a blockage of the nozzle slot or ring nozzle slot, the raw material components, which are larger than the outlet gap width of the nozzle or ring nozzle used, should be comminuted according to the outlet gap width, which is ensured, for example, by a mill upstream of the extruder for comminuting the oversized raw material components can.

A particularly simple procedure is possible if the heat is supplied by a hot air stream. Depending on the process duration and the desired expansion, this should be approx. 200 to approx. 800 ° C hot. In an experimental apparatus, it has been found that hot air temperatures of approximately 300 ° C. to approximately 400 ° C. are sufficient to achieve a satisfactory expansion which is superior to the prior art.

Comparable advantages can of course also be achieved with other heat sources of suitable energy density. Such heat sources can e.g. Infrared heaters, microwave generators or hot gases.

In order to treat the tubular film evenly from the inside and outside, it is advantageous to supply the tobacco film hose with hot air or hot gas both from the outside and from the inside, which can be done, for example, by means of an annular nozzle that surrounds the tobacco film hose , and can be supported by a hot air lance that introduces hot air into the interior of the tobacco film tube. If the film tube by the in the invention Device built-in cutting pins divided into longitudinal strips, so it is ensured even without a lance that hot air flows into the interior of the film tube. Of course, the air or gas quantities that are supplied can usually be regulated. The control is carried out, for example, by means of valves or adjustable fans. Most of the time, the amount of air or gas supplied from inside and outside will be about the same.

The heat supply is controlled so that the tobacco film end product retains a residual moisture of approx. 10 to 20% (wet basis). A lower moisture content of the tobacco film would result in the tobacco film breaking even during the heat treatment or disintegrating into unusable components in a later process step.

The endless tobacco film strips are cut into pieces of approx. 5 to 20 cm long immediately after the heat treatment, which are then either cut separately into threads, the cutting width being approx. 0.5 to 1.5 mm, or they are cut with a Leaf tobacco cut together.

In order to avoid possible blockages of the nozzle or ring nozzle outlet gap, the gap halves are automatically shifted or rotated against each other from time to time, clogging germs being released by the shear forces that occur.

If an annular nozzle is used, which is preferably the case in the present invention, the inner part of the annular nozzle is adjusted by means of a centering screw so that the tobacco film tube emerging from the nozzle mouth has essentially the same wall thickness everywhere.

In order to prevent clogging of the extrusion die slot, it is also possible to apply ultrasound to the die temporarily or permanently. The occurring vibrations loosen existing blockages or prevent the formation of blockages.

In order to take irregularities into account at the start or end of a manufacturing process (e.g. a working day), it is advisable to change the outlet gap width at the nozzle when starting up and shutting down the extruder. In this way, viscosity fluctuations in the raw material that initially occur can be counteracted. The same applies if the extruder is shut down.

Under certain circumstances, it may be advantageous not to seal the tobacco film surface with hot air or gas, but rather by applying a thin layer that is applied before expansion. This can e.g. be useful if the raw mass is to be treated particularly gently. For example, advantageous results of expansion can be achieved by applying water glass and then heating.

Furthermore, gas-forming or driving chemicals can also be added to the raw mass, such as e.g. Sodium bicarbonate, ammonium bicarbonate, and the like, to cause blistering instead of water vapor or in combination with the water vapor after the skin is formed.

However, an additional layer application or also gas-forming chemicals is preferably dispensed with, because the addition or application of these substances can disadvantageously change the nature-identical characteristics of the tobacco film.

A device according to the invention for producing a tobacco film with an extruder is realized in that a nozzle is connected to an extruder, through which the extruded raw material is pressed, in order then to be treated with heat in an expansion chamber.

So that the advantage can be realized that the nozzle or ring nozzle is less or hardly susceptible to blockages, the inner part of the nozzle should be held in a bearing relative to the outer part. As a result, the two gap halves of the nozzle can be easily rotated relative to one another, as a result of which constipation germs can be reduced or avoided. The nozzle mouthpiece can be centered to produce a uniformly thick film. The gap width of the nozzle is adjustable.

The knife edges and other wear parts of the device are easily replaceable.

For the heat treatment process, the expansion chamber must be provided with at least one connection for the supply of hot air or hot gas. Preferably, on the expansion chamber, which preferably has a tubular cross section, at least one connection for the supply of hot air or hot gas, which essentially surrounds the expansion chamber in a ring, and a hot gas or hot air supply, which are arranged essentially centrally in the expansion chamber is. The central arrangement in the expansion chamber is less important than the central arrangement of the hot gas or hot air supply within the tubular tobacco film.

A particularly trouble-free and effective operation of the device can be achieved if the outlet openings of the annular hot gas supply and the connection for the centric supply of hot air or hot gas are arranged so that they are essentially opposite. Of course, the hot gas supplies can also be staggered along the expansion chamber. As a rule, however, it is sufficient to provide an elongated expansion chamber with fewer connections and a central hot gas supply.

In an experimental arrangement, the central hot gas supply consists of a lance-shaped valve, in which the hot gas outlet has a mouthpiece which has the same, but mirror-inverted, longitudinal symmetry as the hot gas supply surrounding the expansion chamber, whereby the hot gas jet emitted by the central hot gas supply is essentially mirror-symmetrical to the hot gas jet which comes from the ring-shaped hot gas supply, the tobacco film being the mirror surface.

In other experimental arrangements, the slotted film tube and a clever flow control ensure that sufficient hot air gets into the interior of the film tube even without a central hot gas supply.

In order to ensure continuous operation, it makes sense to arrange a conveyor belt behind the expansion chamber, which conveys the tobacco film or the endless tobacco film strips to a knife unit that cuts the endless tobacco strips into tobacco pieces of the desired size.

The invention is explained in more detail below on the basis of exemplary embodiments shown in the drawings, from which further advantages and features emerge.

Fig. 1

eine Draufsicht auf einen Tabak-Folienstreifen;

Fig. 2

einen Längsschnitt durch den Tabak-Folienstreifen;

Fig. 3

einen vergrößerten perspektivischen Längsschnitt durch den erfindungsgemäßen Tabak-Folienstreifen;

Fig. 4

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung, insbesondere zur Ausführung des erfindungsgemäßen Verfahrens;

Fig. 5

einen Längsschnitt durch eine Ringdüse und eine Expansionskammer in schematischer Darstellung;

Fig. 6

einen schematischen Längsschnitt durch ein bevorzugtes Ausführungsbeispiel der Ringdüse und einer rohrförmigen Expansionskammer;

Fig. 7

einen Längsschnitt durch die Ringdüse in einer bevorzugten Ausführungsform;

Fig. 8

einen schematischen Längsschnitt durch ein weiteres bevorzugtes Ausführungsbeispiel der Ringdüse und einer rohrförmigen Expansionskammer;

Fig. 9

eine Draufsicht auf eine Vorrichtung gemäß Fig. 8.

Show it:

Fig. 1

a plan view of a tobacco foil strip;

Fig. 2

a longitudinal section through the tobacco foil strip;

Fig. 3

an enlarged perspective longitudinal section through the tobacco film strip according to the invention;

Fig. 4

a schematic representation of a device according to the invention, in particular for executing the method according to the invention;

Fig. 5

a longitudinal section through an annular nozzle and an expansion chamber in a schematic representation;

Fig. 6

a schematic longitudinal section through a preferred embodiment of the ring nozzle and a tubular expansion chamber;

Fig. 7

a longitudinal section through the ring nozzle in a preferred embodiment;

Fig. 8

a schematic longitudinal section through a further preferred embodiment of the ring nozzle and a tubular expansion chamber;

Fig. 9

8 shows a plan view of a device according to FIG. 8.

1 shows a tobacco film strip generally identified by the reference number 10. Bubble-shaped elevations 12 can be seen on the surface of the tobacco foil strip 10. These are extremely different in thickness, as can be seen from FIG. 2.

3 also shows a tobacco foil strip 10 with gas-filled cavities 12. The raw mass from which the tobacco film strip 10 is made consists of a proportion of at least approximately 86% by weight of tobacco particles. In order to impart the necessary moisture content to the tobacco film 10, about 1 to about 6% by weight, in particular 2 to 5% by weight, of humectants are contained. The necessary mechanical cohesion of the tobacco film 10 is achieved by a proportion of binder of approximately 1 to approximately 8% by weight, in particular 3 to 6% by weight. The thickness of the tobacco film 10 without the cavities is between approximately 0.2 mm and approximately 0.4 mm, in particular between 0.2 and 0.3 mm. The starch portion of the binder should contain a maximum of about 2% by weight of starch, insofar as starch is provided at all. In order to maintain the necessary elasticity of the tobacco film 10, a humectant is used, e.g. from glycerin and / or propylene glycol and / or sorbitol or the like. can exist.

The binder can e.g. Carboxymethylcellulose carboxymethylated and / or hydroxyethylated and / or agar-argar and / or alginic acid and their sodium, potassium and / or calcium salts and / or tragacanth and / or guar gum and / or pectin and / or locust bean gum and / or gum arabic.

The cavities 12 shown, which are delimited by a sponge-like structure 16, generally have an expansion in the direction of the film thickness of approximately 0.1 to 5 mm and in the direction of the film width of 0.1 mm to approximately 10 mm, in particular 1 to 5 mm. The sponge-like structure is formed by smaller bubbles 19 in the base material.

The thickness of the relatively gas-impermeable, in particular surface-sealed cover layers 14 is generally extremely small, since the cover layers and the sponge-like structure 16 contribute to the above-mentioned total thickness of the film from 0.2 to 0.4 mm.

The cavities 12 located within the sponge-like structure 16 have a shaggy or furrowed and / or torn, jagged surface 17.

4 shows a device by means of which the tobacco film according to FIGS. 1 to 3 can be produced.

A raw material consisting of a tobacco content of approx. 86 to approx. 98% by weight, a proportion of humectants of approx. 1 to 6% by weight and a binder content of approx. 1 to 8 wt .-%, well mixed, for example larger particles can be crushed using a mill so that they cannot clog the nozzle exit gap 62 in a nozzle 54. In the extruder 52, the raw mass is mixed with a water content of at least 20 to 40%, preferably 30% (water contents are given in relation to the wet basis). This raw mass is extruded at a pressure of approximately 10 to approximately 200 bar, preferably between 50 and 100 bar, with a temperature profile of approximately 30 ° C. to approximately 160 ° C., preferably of 40 to 140, to the extruder 52 ° C.

The raw material is pressed through the outlet gap 62 of the nozzle 54 by the pressure which arises in the extruder, the tobacco film 72 being formed.

The tobacco film 72, which is tubular when an annular nozzle 54 is used, is now introduced into an expansion chamber, where it is initially strongly heated from both sides, so that relatively gas-impermeable cover layers are formed. Due to the heating on both sides, there is initially an increase in the diffusion / flow resistance of the cover layers through a quasi surface plasticization. This first heating process in the expansion chamber 80 can be relatively short, or it can be transferred directly to a further strong supply of heat. With this further strong supply of heat in the expansion chamber 80, an evaporation rate of the present liquid phase is produced, the vapor formation gradient of which is sufficient to build up gas pressures between the previously treated cover layers, which are suitable for creating single-layer gas bubble structures between the prepared cover layers. The heat supply can e.g. be carried out via hot air or hot gas and is symbolized by arrow 82 in FIG. 4.

The expanded tobacco film 72 emerging from the expansion chamber 80 is placed on a conveyor belt 100 and conveyed by the latter to a knife unit 110. The knife unit 110 processes the tobacco film strips 72, which are preferably in the form of endless belts and which are in particular approximately 3 to approximately 5 cm wide, into film strips 120. These are generally 5 to 20 cm long and can then be added separately or together with tobacco leaves Threads are cut.

Temperatures between approximately 200 to approximately 800 ° C. prevail in the expansion chamber 80 during the skin formation process or during the expansion process. Temperatures of 300 to 400 ° C. are preferred. Leave it other suitable heat sources, such as infrared radiators or microwave generators as the sole source of energy or in combination with hot gas supply, are also connected.

In the extruder 52, gas-evolving or driving chemicals can also be added to the raw mass, e.g. Sodium bicarbonate, ammonium bicarbonate and the like. This can be done by adding a minimum of approx. 20 to a maximum of approx. 40% of the water (based on the wet basis).

A sealing layer could also be applied to the tobacco film surface immediately prior to the heat treatment in the expansion chamber 80.

It is of course clear to the person skilled in the art that the desired advantages do not disappear abruptly in the case of modifications and deviations from the stated orders of magnitude and proportions.

The nozzle shown in FIG. 5 is an annular nozzle 54. The raw material from the extruder 52 is introduced into this from above, indicated by the arrow 48. The raw mass is pressed through the space between the inner part 60 and the mouthpiece 64 in the direction of the nozzle outlet gap 62 and through it. The corresponding tobacco film 72 is then introduced into the expansion chamber 80. There it is heated by means of hot air or hot gas, which reaches the expansion chamber 80 through the feeds 82. The hot air is directed along the arrows 83 onto the tobacco foil 72, 92, as a result of which the relatively gas-impermeable cover layers arise on the surface of the tobacco foil and immediately afterwards the expansion of the Tobacco foil is caused. The expanded tobacco foil 92 leaves the expansion chamber 80 on the opposite side.

In principle, the same schematic arrangement as in FIG. 5 can be seen from FIG. 6, except that it is shown here in more detail and with an internal hot air lance 90. Here, too, the raw mass from the extruder 52 enters the ring nozzle 54, indicated by an arrow 48. The raw mass is pressed between the mouthpiece 64 and the inner part 60 of the ring nozzle 54 and cut into strips by cutting knives 56. These tubular tobacco film strips are now inserted into the tubular expansion chamber 80. Hot air or hot gas 84 is introduced into the expansion chamber 80 via the connections 82. A lance-shaped part 90 ensures that the hot air or the hot gas is evenly available for the treatment of the inner surface of the tobacco film. The amounts of hot air or hot gas are proportioned by the annular hot gas supply and the centrally attached, lance-shaped hot air or hot gas supply in such a way that the tobacco film 72, which is present in strips, is mechanically loaded only minimally radially inwards or outwards. The flow vectors of the hot air or the hot gas with which the film is applied to form the essentially gas-impermeable skin and to effect the expansion process are directed in the direction of movement of the film through the expansion chamber.

The central hot gas supply consists of a lance-shaped hot gas supply 90, in which the hot gas outlet 94 has a mouthpiece which has the same longitudinal section symmetry as the annular hot gas supply 81 and / or the expansion chamber 80, but in mirror-inverted form, whereby the hot gas jet emitted by the central hot gas supply 90 is essentially mirror-symmetrical to the hot gas jet coming from the annular hot gas supply 81; the tobacco foil 72, 92 represents the mirror surface.

By means of the ring nozzle 54 shown here, a tobacco film tube slotted into strips has been extruded and has a wall thickness of 0.2 mm. The film strips 72 passed through the expansion chamber 80, which had a diameter of 100 mm and a length of 200 mm, at a speed of, for example, v = 0.06 m / s. The film strips were blown with approx. 300 ° C warm air from two hot air blowers via feed lines 82 with volumes of 500 l / min each. From the inside, the film strips were simultaneously blown with essentially the same amount using a hot air lance with a hot air blower and air heated to about 300 ° C. The tobacco film strips entered the expansion chamber 80 with a moisture content of approx. 40% and left them with a moisture content of approx. 14%.

In order to achieve the expansion effect in an advantageous manner, it is necessary that the heat is transferred to the tobacco foil 72, 92 in the shortest possible time, so that the evaporating moisture does not slowly escape from the tobacco foil without achieving the expansion effect can diffuse out of it.

7 shows the ring nozzle 54 in a preferred embodiment. A raw mass entering the ring nozzle 54 through a line 49, symbolically indicated by the arrow 48, is in the space between the Inner part 60 of the ring nozzle and the mouthpiece 62a of the ring nozzle are pressed. The tobacco film emerges through the outlet gap 62 of the nozzle 54. The thickness of the tobacco film can be adjusted using screw 67. As the tobacco film exits through the annular gap 62, it is separated by cutting knives in the form of cutting pins 68 into strips of the desired width. In the areas at the annular gap 62 where the highest differential pressures occur, wear parts 69, 62a, 68 are used which can be replaced relatively easily and quickly. The inner part 60 of the ring nozzle 54 is quick and easy by means of a screw 67 or the like. Removable from the ring nozzle 54 or reinserted. The mouthpiece 62a can be rotated relative to the inner part 60 or 69 using a ball bearing 63. The adjustable mouthpiece 62a is centered by means of adjusting screws 81. The mouthpiece 62a itself is also easily removable by means of screws.

FIG. 8 shows a schematic arrangement similar to that in FIGS. 5 and 6, only in this case the expansion chamber 80 is divided into two half-shell-shaped halves 82 and 82a, see FIG. 9, which is on the guide rails 22 in the direction of FIG Arrow 23 are arranged to be moved apart. By pushing apart the expansion chamber halves 82, adjustment work on the ring nozzle 54 can be carried out more easily during the start-up and shutdown operation of the extruder 52. In addition, a tube 20 is attached centrally in the expansion chamber 80 and is fastened to the inner ring part 60. The tube 20 provides an annular hot gas flow 83a in the expansion chamber 80. Due to the hot air flowing through the film strips, the tube 20 heats up and ensures that the film strips are heated from the inside.

The tube 20 preferably has a conical end. This conical end of the tube 20 ensures that most of the hot air leaves the expansion chamber upwards. As a result, the film strips are only slightly dried after leaving the expansion chamber 80. Another advantage of the conical design of the end of the tube 20 is the ring nozzle heating by the hot air escaping upwards. If the ring nozzle 54 is not heated, it can lead to faults when the film strips emerge from the nozzle gap.

Claims (35)

1. A sheet with increased filling power comprising tobacco particles, water, binder and moisturizer, characterized by the following features:

   a) the outer surfaces of the sheet (10) are formed by two essentially gas-impermeable, in particular surface-sealed cover layers (14);

   b) between the cover layers (14) there is a layer (16) of spongy structure; and

   c) the layer (16) includes a ply of lenticular gas-filled cavities (12) with shaggy, furrowed and/or torn surface (17).
2. A sheet according to claim 1, characterized in that the proportion of tobacco particles makes up at least about 86-98 % by weight, in particular at least about 92 % by weight, with respect to the total mass without water.
3. A sheet according to claim 1 or 2, characterized in that the proportion of moisturizer makes up about 1 to about 6 % by weight, in particular 2 to 5 % by weight, and the proportion of binder about 1 to about 8 % by weight, in particular 3 to 6 % by weight.
4. A sheet according to one of the claims 1 to 3, characterized in that the binder is an acidic, neutral, basic and/or modified polysaccharide.
5. A sheet according to one of the claims 1 to 4, characterized in that the cavities (12) have an extent in sheet thickness of about 0.1 mm to about 5 mm and in sheet width of about 0.1 mm to about 10 mm, in particular 1 to 5 mm.
6. A sheet according to one of the claims 1 to 5, characterized in that the sheet thickness without taking account of the contribution of the cavities (12) is about 0.1 to 0.4 mm, in particular 0.2 to 0.3 mm.
7. A process for preparing a tobacco-containing sheet with increased filling power according to one of the claims 1 to 6, having the following features:

   a) a raw mass having a tobacco content, a content of moisturizers and a binder content is mixed with a water content in the ratio of 80:20 to 60:40, preferably 70:30;

   b) the moist raw mass is extruded with an extruder (52) at a temperature of about 160°C, preferably up to about 140°C, under pressure and formed to a tobacco sheet (72),

   characterized by the following features:

   c) the tobacco content of the raw mass is about 86 to about 98 % by weight, the moiturizer content about 1 to about 6 % by weight an the binder content about 1 to about 8 % by weight;

   d) the forming pressure lies between about 10 and 200 bar, perferably between 50 and 100 bar;

   e) the tobacco sheet (72) is strongly heated from both sides after the forming , whereby substantially gas-impermeable cover layers (14) form on the tobacco sheet; and

   f) by a further intense supply of heat the water disposed in the tobacco sheet (72) between the cover layers (14) evaporates, gas-filled lenticular cavities (12) and gas-filled bubbles (19) thereby being formed.
8. A process according to claim 7, characterized in that the first strong heating for forming the gas-impermeable cover layers (14) and the further strong supply of heat are carried out in one process step.
9. A process according to claim 7 or 8, characterized in that the raw mass is pressed through a slot nozzle or a ring nozzle (54).
10. A process according to one of the claims 7 to 9, characterized in that the cutters (56) provided at the nozzle (54) cut the emerging tobacco sheet (72) into strips (72) which are in particular about 3 to 5 cm wide endless strips.
11. A process according to one of the claims 7 to 10, characterized in that the further intense heat supply is effected by hot air at a temperature of about 200 to 800 °C, peferably 300 to 400 °C.
12. A process according to one of the claims 7 to 11, characterized in that the further intense heat supply is effected by a medium of suitable energy density such as infrared radiation, microwaves or hot gases.
13. A process according to one of the claims 7 to 12, characterized in that the hot air or gas streams heat the tobacco sheet from both sides.
14. A process according to one of the claims 7 to 13, characterized in that the heat supply is controlled so that the tobacco sheet product retains a residual moisture of about 10 to 20 % (wet basis).
15. A process according to one of the claims 7 to 14, characterized in that with an extruded hose-like tobacco sheet (72, 92) for the heat treatment method steps substantially the same hot air or hot gas amounts are supplied within the expansion chamber both outside and inside the tobacco sheet.
16. A process according to one of the claims 7 to 15, characterized in that the gap-forming parts of the nozzle (54) are intermittently or permanently displaced or turned with respect to each other.
17. A process according to one of the claims 7 to 16, characterized in that the nozzle (54) is intermittently or permanently subjected to ultrasonic radiation.
18. A process according to one of the claims 7 to 17, characterized in that the gas-impermeability of the cover layers (14) is obtained by bilateral application of thin layers to the tobacco sheet surface before said tobacco sheet is heat treated in the expansion chamber.
19. A process according to one of the claims 7 to 18, characterized in that the propellant or gas-developing chemicals such as sodium hydrogencarbonate, ammonium hydrogencarbonate or the like, are added to the raw mass.
20. An apparatus for preparing a tobacco-containing sheet for carrying out the process according to claims 7 to 19, comprising

    a) an extruder having a nozzle,

    characterized by the following features:

    b) the nozzle (54) is followed by an expansion chamber (80) through which the tobacco sheet (72) formed by the extruder (52) is passed;

    c) the expansion chamber (80) is connected to a heat source in such a manner that the tobacco sheet (72) passing through the expansion chamber (80) is intensely heated from both sides so as to form essentially gas-impermeable cover layers (14), a spongy intermediate layer (16) having bubbles and lenticular cavities (12); and

    d) a heat source for vaporization of the water in the tobacco sheet (72) between the cover layers (14) is provided.
21. An apparatus according to claim 20, characterized in that the extruder (52) is preceded by a mill for grinding large tobacco particles.
22. An apparatus according to one of the claims 20 to 21, characterized in that the nozzle (54) is a ring nozzle or a slot nozzle.
23. An apparatus according to one of the claims 20 to 22, characterized in that the nozzle (54) is provided with cutter blades (56), cutter pins or the like.
24. An apparatus according to claims 20 to 23, characterized in that the gap-forming parts (60, 62a) of the nozzle (54) are intermittently or permanently displaced or turned with respect ot each other.
25. An apparatus according to one of the claims 20 to 24, characterized in that with a ring nozzle the outer and inner parts are rotatable with respect to each other via a ball bearing (63).
26. An apparatus according to one of the claims 20 to 25, characterized in that the gap width is adjustable via a screw (67).
27. An apparatus according to one of the claims 20 to 26, characterized in that the expansion chamber (80) is provided with at least one connection (82) for the supply of hot gas, in particular hot air.
28. An apparatus according to one of the claims 20 to 27, characterized in that the expansion chamber (80) is connected to a heat source of adequate energy density, for example an infrared radiator or a hot-gas generator.
29. An appparatus according to one of the claims 20 to 28, characterized in that the expansion chamber (80) has a tubular cross-section.
30. An apparatus according to one of the claims 20 to 29, characterized in that the expansion chamber (80) is divided into two half-shell-like halves (82, 82a) which are arranged on guide rails (22) and adapted to be pushed apart.
31. An apparatus according to one of the claims 20 to 30, characterized in that in the interior of the expansion chamber (80) a hot-gas supply means (90) is disposed.
32. An apparatus according to one of the claims 27 to 31, characterized in that the connection (82) for the supply of hot air surrounds the expansion chamber (80) substantially annularly.
33. An apparatus according to one of the claims 27 to 32, characterized in that the exit opening (81) of the hot-air supply means and the exit opening (94) of the hot-gas or hot-gas supply means in the interior of the expansion chamber (80) are so arranged that they lie substantially opposite each other.
34. An apparatus according to one of the claims 3o to 33, characterized in that the hot-gas supply means in the interior of the expansion chamber (80) comprises a lance-shaped hot-gas supply means (90) with a mouthpiece which in the longitudinal direction is inversely symmetrical to the mouthpiece of the hot-air supply means (81), the hot-gas jet emitted by the hot-gas supply means (90) thereby being substantially in lateral inverted symmetry with the hot-gas jet coming from the hot-air supply means (82) at the outer periphery of the expansion chamber (80), the tobacco sheet (72, 92) representing the mirror surface of the lateral inversion.
35. An apparatus according to one of the claims 20 to 33, characterized in that to the inner part (60) of the ring nozzle (54) a tube (20) is attached which is disposed centrally in the expansion chamber (80).

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