AP232A - Tobbacco sheet and method and apparatus for the production of a tobbacco sheet. - Google Patents

Abstract

With the present invention a tobacco sheet or foil is proposed which has an elevated filling force and consists of tobacco particles, water, binders and moisturizers, two relatively gas-impermeable, in particular surface-sealed cover layers being connected together by a spongy structure which is formed by gas-filled bubbles, and in which cavities are formed having a shaggy, furrowed and/or torn surface.

Description

BACKGROUND CF THF INVENTION

1. Field of the Invention

The invention relates to a tobacco sheet of elevated filling power comprising tobacco particles, binder and moisturizer, as well as a method for producing such a sheet and an apparatus for producing such a sheet.

2. Description of the Frier Art

In the production cf tobacco sheet or foil pieces from tobacco dust, tobacco fines and the tobacco stamps, it is known to extrude a foam product from said starting materials. A disadvantage here is the relatively high amount required cf binders, in particular starch, which can easily lead to impairment of flavour, aroma and burning behaviour of smckable articles.

US-PS 3,098,492 and DE-OS 2,804,772 describe the extrusion of a foil or sheet by means of a slot nozzle; such a cethod would however be complicated and expensive if it were desired to produce therewith a sheet or foil having a filling power, comparable to tobacco and moreover a high tobacco content and lew binder contents. This would be possible only w.th nozzle cap widths < 0.15 mm.

A factor here is that the filling power cf the tobacco sheet depends decisively on the minimum possible thickness corresponding to a small nozzle gap width of the extrusion nozzle and for this reason the entire tobacco starting material must be present ground reliably to a maximum grain size. Tobacco particles in the raw mass of the tobacco starting material which are too large can easily clog such an extrusion nozzle, entailing complicated monitoring steps or

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AP Ο Ο Ο 2 3 2 requiring extremely reliable and thus complicated comminution methods .

Tr.e production of a sheet or foil by extrusion of the starting material using a slot nettle in a roller nip is also known from U5-PS 2,093,492, DE-CS 2,804,772 and GB-PS 1,455,218. In these cases as well, the aforementioned disaJvantages cf the low filling power compared with leaf material occur. In addition, the rollers forming the gap when operating with a slot nozzle can run with only a small peripheral speed and consequently a high torque is necessary, leading to high strain cf the roller structure for relatively low throughput. An. increase in the throughput can only be achieved by increasing the roller width; this in turn requires an extremely large slot nozzle, a stable roller structure and a large roller thickness in order to minimize the sagging of the rollers. Moreover, as a rule a multiple calender must be used because a single deformation step does not suffice for achieving the uniform required thickness.

In another known method (DE-OS 3,104,098, DE-PS 2,055,672, DE-PS 2,421,652, DE-PS 3,224,416 and GB-PS 1,459,218), Of making tobacco foils or sheets by means of rollers or rolls, an extremely high amount of water must be added to the starting material, in the range of 30 to 50 %, making subsequent drying necessary. This increases the necessary technical expenditure for the method. Moreover, in this case frequently undesired organic solvents are used, for example methylene chloride. Finally, in this case as well as a rule a multistage rolling apparatus or a calender is required.

A method an apparatus for reprocessing tobacco is k.ncw.n from DE-PS 3,339,247. Dust-like tobacco particles are worked with binders and possibly additives to give a plastifiable mixture which is extruded to form individual rodlike intermediate products. Said rodlike intermediate products are then processed to sheet pieces by reforming a cylindrical skein from the plasticized mixture in an extruder to a thin-walled

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AP 0 0 0 2 3 2 continuously widening hollow body and split into threadlike intermediate products which become crimped. The threadlike crimped intermediate products are then cut to give the individual crimped fibre pieces. The intermediate products have a relatively dense structure which moreover due to the additives differs from the quality features cf natural tobacco .

t.nat extrudate is stret

To-CS 3,294,461 discloses a tobacco reconstitution method in w.nicn a mixture cf tobacco particles, starch and binders is extruded with addition cf water to form a striplike extrudate, the extrusion conditions and the recite being such that the extrudate cn leaving the exit aperture cf the extruder nozzle assumes a cross-secticn which is greater than f the exit aperture cf the extruder nozzle, and the >d in its plastic phase to reduce its thickness dimensions, the stretching ratio being at least 1.5; the stretched extrudate is cut to give particles which each have a cellular structure and an integral skin. The stretching or drawing operation here is relatively complicated. if tearing of the tobacco sheet occurs in this case it leads tc a loss of time and material during the production. Another disadvantage is the necessary high amount of binder, leading to impairment of the flavour and aroma .

DZ-cs 3,804,459 discloses a tobacco reconstitution method in which a mixture cf tobacco particles, starch and binder as well as water is supplied to an extruder, the operating conditions and the recipe being such that the water from the striplike extrudate by evaporation in order to thereby expand the extrudate. After the cooling the extrudate is cut into particle size. The particles, each of which has a cellular inner structure and a skin on two ocpoeitely diepoeed sides may be used as cr in cigarette filling material.

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However, a disadvantage with this tobacco reconstitution method, as already indicated, is that large amounts of starch and hinders are necessary and this leads to changes in the flavour and arena of the tobacco material.

T“ 33 23 663 C2 discloses a filling material of reconstituted tobacco material ar.d a method for the production thereof. Zn this case, two separate sheet sections are locally adhered together, cavities forming between the two adhered sheet sections. This procedure is complicated, troublesome ar.d provides sheet material of only low filling capacity. Moreover, the apparatus for carrying cut the known method is complicated and involved.

CE 31 47 846 C2 relates to a method or a totaccc material witn which by increasing the ceil structure of the tobacco through a pressure reduction and pronounced temperature increase an expansion is achieved. However, such a method is possible only with natural tobacco material and is not suitable for reconstituted tobacco material because in this case no expandable ceil structures are available.

EP 0 198 718 A2 discloses a method with which a reconstituted tobacco material of tobacco waste is expanded during the extrusion. The expansion is effected by a high extrusion temperature and an abrupt pressure reduction on leaving the extruder in conjunction with an adequate sheet thickness and a content cf binder cf at least about 1C This production meohed is obviously based on completely different principles and also gives a completely different product which due to its high tinder content is very unsatisfactory as regards its flavour, burning properties and the like.

EP C 046 018 Al also discloses a method for producing reconstituted tobacco material. However, this method is based only on the stiffening of the material and fixation of the stiffening. The reconstituted tobacco material is greatly overdried and thereafter again moisturized. As a r

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AP Ο Ο Ο 2 3 2 result, the reconstituted tobacco material loses a greater part cf its flavouring substances and becomes extremely critical in its handling because with increasing drying it becomes extremely brittle and friable. This method thus also results in a product which is unsatisfactory.

DE 28 19 524 Cl describes a thin compact tobacco product without air inclusions in which by extrusion a plurality of material reds cr skeins are formed which are then rolled together again, to form a rconepiy material layer.

The invention therefc sheet with increased con 5uepc i or. c f which forth above do r.ot cc method in particular re has as its object the provision cf filling power ir. the production and the disadvantages of the prior art set our, as well as an apparatus and a for producing such a tobacco sheet.

Mere especially, the invention has as its object the production cf a sheet which is completely or almost completely satisfactory in the factors flavour, aroma, colour, ash and smoke properties, density, elasticity and fragility, so that the properties thereof hardly differ from those of the tobacco; furthermore, the objective is to provide a method and an apparatus with which it is possible to make such a sheet in simple manner.

The invention therefore proposes in a sheet of elevated filling power comprising tobacco particles, water, binder and moisturizer the improvement wherein the outer surfaces of the sheet are formed by two relatively gas-impermeable, in particular surface-sealed cover layers; between the cover layers there is a layer of spongy structure; and the layer includes a ply of lenticular gas-filled cavities with shaggy, furrowed and/or torn surface.

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Trie invention further proposes in a method for producing such a srieet containing tobacco and having elevated filling power '.'herein a raw mass having a tobacco content, a content cf moisturizers and a binder content is mixed with a water content in trie ratio ci 80:23 to 60:40, preferably 70:00; the moist raw mass is extruded with an extruder at a temperature of about 16O°C, preferably up to about i<;o^eC, under pressure and formed to a tobacco sheet, trie improvement in which trie tobacco content of the raw mass is about 86 to 98 % by weight, trie moisturizer content about 1 to 6 % by weight and trie binder content about 1 to 8 % by weight; trie forming pressure lies between about 10 and 200 bar, preferably between 50 and ICO tar; trie tobacco sheet is strongly heated from both sides after trie forming, substantially gasimpermeable cover layers thereby forming on the tobacco sheet; and by a further intense supply of heat trie water disposed in. the tobacco srieet between the cover layers evaporates, gas-filled lenticular cavities and gas-filled bubbles thereby being formed.

The invention also proposes in an apparatus for producing a tobacco-containing sheet, comprising an extruder having a no22le the improvement in which the nozzle is followed by an expansion chamber through which tobacco sheet formed by the extruder is led; the expansion chamber is connected to a heat source in such a manner that the tobacco sheet passing through the expansion chamber is intensely heated frcm bcth sides so as to form relatively gas-impermeable cover layers, and a spongy intermediate layer having bubbles and lenticular cavities.

Advantageous and expedient embodiments or variants are defined by the features in the subsidiary claims.

A raw mass of tobacco particles, water, binder and moisturizers is processed to the sheet according to the invention which consists of two relatively gas-impermeable in particular surface-sealed cover layers at the cuter surfaces,

AP Ο Ο Ο 2 3 2 the cover layers being connected together via a spongy str-ct_re containing gas-filled bobbles; gas-filled cavities are fcrned between the cover layers, said cavities being provided with a shaggy, furrowed and/or torn surface. In its burning behaviour the tobacco sheet or foil according to the invention is in sone cases better than average tobaccos.

3y the two relatively sealed cover layers i production precess to treasure within the t: the filling power inc:

:s of time gas-ireperreeable, in particular surface. is possible on the one hand during the generate an extremely high expansion bacco sheet and cn the other to retain ease obtained in. this ranter for very

Decisive in cbtainir.g the desired quality factors, flavour, arena and colour, is that at least about S5 I by weight, in particular 92 % by weight, tobacco particles are present in the raw reass processed to the tobacco sheet or foil according to the invention. In this tanner, the extrereely costmcer.sive tobacco can be processea almost without waste to give high-quality smckable articles.

To er.e-jx*e a n ·ί-·»»*Γγ «luaLiclvy qiU λ 3tr»n<-jrh of thr tobacco sheet comparable to the natural leaf, it is advantageous to make the tobacco sheet having a moisturizer content of about I to 6 % by weight, in particular 2 to 5 % by weight, so that said tobacco sheet can retain a certain moisture content cf about 10 to 14 % (wet basis) after the production and even for relatively long periods cf tire.

If this residue of moisture were tco low, it would not be possible to carry cut an extensive further precessing of the tobacco sheet.

Disregarding the contribution of the cavities, the thickness of the sheet should lie between about 0.1 rem and c.4 rem; in particular, sheet thicknesses between 0.2 and C.3 rem are advantageous in order to ensure a contribution to the desired .natural tobacco features.

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The binder should not contain mere than about 2 1 by weigh starch at the most in order to avoid the occurrence cf any disadvantageous changes in the flavour and arena cf the sheet.

Tc obtain the expansion effect according to the invention it is net absolutely essential to add starch.

To give the tobacco sheet according to the invention the

These advantages for achieved in that the the tobacco sheet can be further binder contains carbcxymethvl cellulose, carboxymethylated and/or hydrexyethylated and/or agar-agar and/or alginic acid or their sodium, potassium and/or calcium salts and/or tragaca.nth and/or guar seed flour and/or pectin and/or carob seed flour and/or gum arabic.

The cavities generated in the layer of the tobacco sheet may in principle have any desired size relatively to the sheet size. With regard to a nature-identical burning behaviour, the filling power, and other features of burning tobacco, extents of the cavities in the sheet thickness have proved advantageous which are cf the magnitude of about 0.1 to 5 nn. and in the direction of the sheet width cf about C.l to 10 mm, in particular frcm. 1 to 5 mm.

To produce the tobacco sheet according to the invention with elevated filling power a raw mass is precessed which consists cf about 86 to 98 % by weight tobacco material, of a content of moisturizers of about l to 6 % by weight and a binder content cf about 1 to 8 I by weight. This raw mass is mixed with a water content cf about at least 20 t, in particular 20 to 40 %, preferably 30 % (all wet basis). The raw mass is extruded at a pressure of about 10 to 200 bar, preferably

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AP0 OO 2 3 2 between 50 and 100 bar, to give the tobacco sheet, the extruder having a temperabure profile of about 30^aC to 160*0. Preferably, a temperature profile cf 4O°C to liO’C is used. The raw mass is expelled at ~ the extruder cutlet through a

,.e cr :h exit gaps,

•.ereb’.

rning the tobacco sheet. The tobacco sheet is thereafter strongly heated from both sides in a relatively short time, thereby forming relatively gas-impermeable cover layers. By a further intense supply cf heat the water disposed in the tobacco sheet in the layer between the cover layers is evaporated, therebv f crnir.a gas-filled cavities and bubbles.

Advantageously, the method step for forming the relatively gas-impermeable cover layers and the bubble-iike cavities ma; be combined to one method step, this greatly reducing both the method technology involved and the apparatus expenditure, As nozzle die slot or ring nozzles may be employed.

If a ring nozzle is used as .nozzle a continuous tobacco sheet hose can be produced which is advantageously provided at the ring nozzle gap with a plurality of cutters, the tobacco sheet thereby being cut into longitudinal strips preferably emerging as endless strips, in particular with a width of about 3 to 5 cm, frcm the nozzle mouth. A tobacco sheet prepared in this manner can be further processed particularly effectively and without excessive apparatus expenditure. To largely eliminate ar.y clocamg cf the nozzle slot or ring nozzle slot, the raw mass constituents which, are larger than the exit gap width cf the nozzle or ring .nozzle used should te comminuted to correspond to the exit gap width and this can for example be ensured by a mill preceding the extruder for comminuting the raw mass constituents which are too large .

A particularly simple method procedure is possible if the heat supply is produced by a hot air stream. The temperature of the latter should be about 200 to 800^eC, depending on the process duration and the desired expansion. In a test

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APO 0 0 2 3 2 ίο apparatus it has been found that hot-air temperatures of about 303°C to 4OC*C suffice tc obtain satisfactory expansion excelling the prior art.

Comparable advantages can also of course be achieved with, other heat sources cf suitable energy density. Such, heat sources may fcr example be infrared radiators, microwave generators or hot gases.

To treat the sheet foil uniformly from the inside and outside it is advantageous to supply hot air or hot gas to the tobaoco sheet hose both, from the outside and from the inside and this can fcr example te done from the outside by an annular nozzle which surrounds the tobacco sheet hose and can be assisted by a hot-air lance which introduces hot air into the interior cf the tobacco sheet hcse. If the sheet hose is divided by the cutting pins installed in the apparatus according to the invention into longitudinal strips it is ensured even without a lance that hot air flows into the interior of the sheet hose. Of course, as a rule the air and gas amounts supplied are regulatable. The regulation is for example carried cut by means of valves or adjustable fans. Usually, the air and gas amounts supplied from the inside and outside will be of substantially the same size.

The heat supply is controlled in such a manner that the tobacco sheet end product retains a residual moisture of about 10 to 20 % (wet basis). A lower moisture content cf the tcoacoc sheet would lead to said sheet breaking during the heat treatment itself or disintegrating in a subsequent method step into components which are of no use.

The endless tobacco sheet strips are cut immediately after the heat treatment into pieces about 5 to 20 cm in length which are then either separately cut to filaments, the cut width being about 0.5 to 1.5 mm, or cut together with a leaf tobacco.

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To avoid possibly occurring clogging of the nozzle or ring nozzle exit 5a?/ trie gap halves are automatically displaced or turned from. time tc tone with respect to each other, the cloggong nuclei! thereby being detached by the shearing forces rising.

If a ring nozzle is used, as is preferably the case with the present invention, trie inner part cf the ring nozzle is adjusted by means of a centering screw in such a manner that the tocaccc sheet hose emerging from the nozzle mouth has substantially the same wall thickness everywhere .

To avoid clogging of trie extrusion nozzle slot it is also possible to subject the nozzle intermittently cr permanently to ultrasonic radiation. The vibrations occurring loosen the clogging present cr prevent the formation cf clogging nuclei!.

Tc take account of irregularities at the start or end cf a production sequence (for example of a working day) it is expedient to vary the exit gap width at the nozzle when starting or shutting down the extruder. In this manner initially occurring viscosity fluctuations in the raw mass can be compensated. The same applies when the extruder is shut down.

It may possibly te advantageous net to seal the tobacco sheet surface with hot air cr gas but to apply a thin layer which is applied before the expansion. This may for example be expedient when the raw mass has to be treated particularly gently. Thus, for example, by applying water glass and subsequent heating it is certainly possible to obtain advantageous expansion results.

Furthermore, it is also possible to add to the raw mass gasforming or propellant chemicals, such as sodium hydrocencarbonate, ammonium hydrogencarbonate and the like, bad ORIGINAL $

AP Ο Ο Ο 2 3 2 so as instead of the water vapour or in combination therewith to effect the bubble formation after formation of the skin.

Preferably, however, additional layer application cr also gas-forming chemicals are dispensed with because the addition or acolication of these substances can disadvantageous^' alter the nature-identical features of the tobacco sheet.

An apparatus according to the invention for producing a c ob a cco sheet and corneris ing an extruder is implemented in that to an extruder a nozzle is connected through which the extruded raw mass is forced in order to be subsequently treated with heat in an expansion chamber.

Tc enable the advantage of making the nozzle or ring nozzle less cr hardly pror.e to clogging, the inner part of the nozzle should be mounted in a bearing with respect to the outer part. As a result the two gap halves of the nozzle can easily be turned with respect to each ether, thereby dim.nishir.g clogging nuclei! or avoiding them. To achieve a uniform foil or sheet thickness the mouthpiece of the nozzle can be centred. The gap width of the nozzle is adjustable.

The cutters and other wearing parts of the apparatus are mounted for easy replacement.

For the heat treatment process the expansion chamber must be provided with at least one connection for the supply of hot air cr hot gas. Preferably, at the expansion chamber, which preferably has a tubular cross-section, at least one connection for the supply of hot air or hot gas is provided and substantially an.nularly surrounds the expansion chamber, as well as a hot-gas cr hot-air supply means which is substantially centrically arranged in the expansion chamber.

It is net so much the central arrangement in the expansion, chamber which ie important as the central arrangpment of the hot-gas or hot-air supply means within the tubular tobacco sheet.

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A particularly troublefree and effective operation cf the apparatus can be achieved if the exit apertures cf the annular hot-gas supply and the connection for the central s-pply cf hot air or hot gas are arranged in such a manner that they are substantially opposite each other. Of course, the hot-gas supply means can also be arranged staggered along tne expansion chanter. However, as a r _ le it suffices to provide an elongated expansion chamber with less connections and a central hot-gas supply.

In one experimental arrangement the central hot-gas supply consists cf a lance-shaped valve in which the hot-gas outlet has a mouthpiece which has the same but laterally inverted longitudinal symmetry as the hct-gas supply means annularly surrounding the expansion chamber and as a result the hot-gas jet emitted by the central hct-g3s supply means is substantially in laterally inverted symmetry with the hot-gas jet which comes from the annular hct-gas supply means, the tobacco sheet representing the surface of mirror inversion.

In other experimental arrangements, by the slit sheet hose and appropriate flow guiding it is ensured even without central hot-gas supply that adequate hot air reaches the interior of the sheet hose.

To ensure continuous operation it is expedient to arrange behind the expansion chamber a conveyor belt which conveys the tobacco sheet or the endless tobacco sheet strips to a cutter mechanism which cuts the endless tobacco strips into tobacco nieces of the desired size.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter with reference to some exarples of embodiment illustrated in the drawings, from which further advantages and features are apparent ar.d in which:

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	APO0023 2 i4
Fig. 1	is a plan view of a tobacco sheet strip;
Fig. 2	is a longitudinal section through the tobacco sheet strip;
Fig. 3	is an enlarged perspective longitudinal section through the tobacco sheet strip according to the invention;
Fig. 4	is a schematic illustration of an apparatus according to the invention, in particular for carrying out the method according to the invention;
Fig. 5	is a longitudinal section through a ring nozzle and expansion chamber ir. schematic representation;
Fig. 6	is a schematic longitudinal section through a preferred example of embodiment of the ring noz2le and a tubular expansion chamber;
Fig. 7	is a longitudinal section through the ring nozzle in a preferred embodiment;
Fig. 3	is a schematic longitudinal section through a further preferred example of embodiment of the ring nozzle and a tubular expansion chamber;
Fig. 9	is a plan view of an apparatus according to Fig. 8.

DESCRIPTION OF PREFERRED EMBODIMENTS

In Fig. 1 a tobacco sheet strip denoted generally by the reference numeral 10 can be seen. On th· surface of the tobacco sheet or foil strip 10 blister-like protrusions 12

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AP Ο Ο Ο 2 3 2 is can be seen. These are extremely different in their thickness as can be seer, frtm Fig. 2. Fig. 3 also shews a tobacco sheet strip 10 having gas-filled cavities 12. The raw mass iron which the tobacco sheet strip 10 is made has a content of at least about 36 % by weight tobacco particles.

To give the tobacco sheet 10 the necessary moisture content, about 1 to 6 % by weight, in particular 2 to 5 % by weight, moisturizers are contained therein. The necessary mechanical cohesion of the tobacco sheet 10 is achieved by a content of binder cf about 1 to 3 I by weight, in particular 3 to 6 % by weight. The thickness of the tobacco sheet 10 without the cavities lies between about 0.2 tc and 0.4 mm, in particular between 0.2 and 0.3 mm. The starch proportion of the tinder should be about 2 % ty weight at the most, if indeed starch is provided at all. To retain the necessary elasticity of the tobacco sheet 1C a moisturizer is used which may consist for example of glycerol and/or propylene glycol and/or sorbitol or the like.

The binder may fcr example contain carboxymethyl cellulose, carboxymethylated and/cr hydroxyethylated and/or agar-agar and/or alainic acid or their sodium, potassium and/or calcium salts and/or tragacar.th and/or guar seed flour and/or pectin and/or carob seed flour and/or gum arable.

The cavities 12 illustrated and defined by a spongy structure 16 have as a rule in the direction cf the sheet thickness an extent of about 0.1 to 5 mm ar.d in the direction of the sheet width of C.I mm to about 10 mm, in particular 1 to 5 m. The spongy structure is formed ty relatively small bubbles or blisters 19 in the foundation material. The thickness of the relatively gas-impermeable in particular surface-sealed cover layers 14 is usually extremely small because the cover layers and the spongy structure 16 make a contribution of 0.2 to 0.4 mm to the aforementioned total thickness of the sheet.

The cavities 12 disposed within the spongy structure 16 have a shaggy, furrowed and/or torn pitted surface 17.

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AP Ο Ο Ο 2 3 2 rig. 4 shows an apparatus which can be used to make the tobacco sheet according to Figures 1 to 3.

In the extruder 52 a raw cass consisting cf a tobacco content of about 86 to 53 % by weight, a content of moisturizers of about 1 to 6 % by weight ar.d a binder content of about i to 8 % by weight is thoroughly nixed and using for example a mill larger particles are comminuted 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 proportion of at least 20 to 40 *, preferably 30 % (water contents are indicated with respect to the wet basis). This raw cass is extruded at a pressure of about 10 to 200 tar, preferably between 5C and 100 bar, a temperature profile of about 30^eC to 16O°C, preferably 40 to 140^eC, being applied to the extruder 52.

The pressure forming in the extruder expels the raw mass through the exit gap 62 cf the nozzle 54, giving the tobacco sheet 72.

The tobacco sheet 72, which is hose-shaped when using a ring nozzle 54, is new introduced into an expansion chamber where it ic initially strongly heated frnm both sloes so that relatively gas-impermeable cover layers form. The bilateral heating initially leads due to a quasi surface plastifying to an increase of the diffusion/flow resistance of the cover layers. This first heating operation in the expansion chamber 80 may be relatively short or alternatively merge directly into a further intense supply cf heat. On this further intense supply of heat in the expansion chamber 60 an evaporation rate of the liquid phase present is produced having a vapour formation gradient sufficient to build up gas pressures between the previously treated cover layers which are able to form mcncply gas bubble structures between the prepared cover layers. The heat supply may for example be via hot air cr hot gas and is indicated by the arrow 62 in Fig. 4.

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The expanded tobacco sheet 7 2 emerging from the expansion chamber 80 is placed on a conveyor belt 100 and conveyed by the latter to a cutter mechanism lie. The cutter mechanism. 110 precesses the tobacco sheet strips 72, which are preferably present as endless strips and in particular have a width of about 3 to 5 cm, to give sheet strips 12C. The latter are as a rule 5 to 20 cm long and may subsequently be cut separately or together with tobacco leaves to give filaments .

c_r-;.g the skin formation process and during the expansion process temperatures between about ICO to SCC’C obtain in the expansion chamber 80. Preferably, the oceration is carried out with, temperatures of 3CO to 4C0’C. Other suir.ible heat sources may also be used, for example infrared r*d-ators or microwave generators as sole energy dispensers or in combination with het-gas supply.

To the raw mass in the extruder 52 gas-developing cr propellant chemicals may also be added, for example sodium hydrogencarbonate, ammonium hydrogencarbonate and the like. This can be done in amplification of the admixture of water in an amount of at least about 20 to at the most about 40 % (with respect to the wet basis).

Immediately pricr to the heat treatment in the expansion chamber 80 a sealing layer could also be applied to the tobacco sheet surface.

It will cf course be clear to the person skilled in the art that the desired advantages do net appear abruptly on modification and deviation from the orders of magnitude and quantity ratios specified.

The nozzle pictured in Fig. 5 is a ring nozzle 54. The raw mass is introduced by the extruder 52 into said nozile from above as indicated by the arrow 48. The raw mass is forced

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AP Ο Ο Ο 2 3 2 _1β through the intermediate space between the inner part 60 and the mouthpiece 64 in the direction towards the nozzle exit gap 62 and forced through the latter. The corresponding tobacco sheet 72 is subsequently introduced into the expansion chanter £0. There it is heated by means of hot air or hot gas which enters the expansion chamber 80 through the supply means 82. The hot air is directed along the arrows 83 onto the tobacco sheet 72, 32, thereby forming the relatively gas-impermeable cover layers on the surface of the tobacco sheet immediately after the expansion of said sheet. The expanded tobacco sheet 92 leaves the expansion chamber 80 on the ootosite side.

In Fig. 6 fundamentally the same arrangement as in Fig. 3 is shown but in this case in mere detail ar.d with the inner hotair lance 90. In this case as well the raw mass from the extruder 52 enters the ring nozzle 54 as indicated by an arrow 48. The raw mass is forced between the mouthpiece 64 and the inner part 60 of the ring nozzle 54 and is cut by cutters 56 to form strips. These tobacco sheet strips arrayed in hcse-like manner are now introduced into the tubular expansion chamber 80. Hot air or hot gas 84 is introduced via the connections 82 into the expansion chamber 80. A lance-like member 50 ensures that the hot air or het gas is also available uniformly for the treatment of the inner surface cf the tobacco sheet. The hot air or hot gas amounts from the annular het-gas supply means and the centrically arranged lance-like hot-air cr hot-gas supply means are proportioned so that the tobacco sheet 72 present in strips is subjected only to a minimum mechanical load radially inwardly or outwardly. The flew vectors of the hot air or the hot gas to which the sheet is subjected to form the substantially gas-impermeable skin and effect the expansion process are directed in the direction of movement of the sheet through the expansion chamber.

The central hot-gas supply means consists of a lance-like hot-gas supply means 90 in which the hot-gas outlet 94 has a

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AP Ο Ο Ο 2 3 2 η mouthpiece which has the same longitudinal sectional symmetry as the annular hot-gas supply means 81 and/or the expansion chamber 8C, although in laterally inverted form, and as a result the hot-gas jet emitted by the central hot-gas supply means SC is substantially in laterally inverted symmetry with the hot-gas jet coming from the annular hot-gas supply means 31; the tobacco sheet 72, 92 represents the mirror surface cf said symmetry.

3y means of the ring nozzle 54 illustrated here a tobacco sheet tube slit into strips has been extruded and has a wall thickness cf 3.2 mm. The sheet strips 72 passed with a velocity of for example v = C.C6 m/s through the expansion chamber 30 which had a diameter cf 100 mm and a length of 210 mm. As this was done, air at a temperature of about 300°C was blown by two hot-air fans via conduits 82 with volumes cf 500 1/cir. each onto the foil strips. From the inside the sheets were simultaneously subjected to hot air at about 300⁵C in substantially the same amount through a hot-air lance with a hot-air fan. The tobacco sheet strips entered the expansion chamber 80 with a moisture content of about 40 % and left said chamber with a moisture content of about 14 i.

To achieve the expansion effect to an advantageous extent it is necessary to transfer the heat to the tobacco sheet 72, 52 in the shortest possible time tc avoid the evaporating moisture from escaping from the tobacco sheet cr diffusing out of said sheet slowly without generating the expansion effect.

In Fig. 7 the ring nozzle 54 is shown in a preferred embodiment. A raw mass entering through a conduit 49 into the ring nozzle 54 and indicated symbolically by the arrow 43 is forced into the intermediate space between the inner part 60 of the ring nozzle and the mouthpiece 62a of said nozzle.

The tobacco sheet emerges from the exit gap 62 of the nozzle 54. The thickness of the tobacco sheet is adjustable via the

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AP Ο Ο Ο 2 3 2 20 screw 67. On leaving through the ring gap 62 th· tobacco sheet is cut by the cutters in the form of cutting pins 63 into strips of the desired width. In the regions at the ring gap 62 where the greatest differential pressures occur the wearing parts 69, 62a, 63 are used which can be replaced relatively easily and quickly. The inner part 60 of the ring nozzle 54 can also easily and rapidly be removed or reinserted from or into the ring noz2le 54 by means of a screw 67 cr the like. By using a ballbearing 63 the mouthpiece 62a can turn with respect to the inner part 60 cr 69. The centering of the adjustable mouthpiece 62a is made via adjusting screws SI. The mouthpiece 62a itself is likewise mounted in easily detachable manner by means of screws .

In Fig. S a schematic arrangement is shown similar to that in Figs. 5 and 6 but in this case the expansion chamber 80 is divided into two halves 82 and 82a in the form cf halfshells, cf. Fic. 9, which are arranged on guide rails 22 and adapted to be pushed apart in the direction of the arrow 23. By pushing apart the expansion chamber halves 82 the adjustment work on the ring nozzle 54 during the starting and closing down operation of the extruder 52 Is made easier. In addition, in the centre in the expansion chamber 80 a tube 20 is disposed which is mounted on the ring nozzle inner part 60. The tube 20 ensures in the expansion chamber 80 an annular hct-gas flew 33a. The tube 20 is heated up by the hot air flowing through the sheet strips and provides for the heating cf said heat strips from the inner side.

The tube 20 preferably has a conical end. This conical end cf the tube 20 ensures that the greater part of the hot air leaves the expansion chamber upwardly. As a result, the sheet strips are only slightly afterdried after leaving the expansion chamber 80. A further advantage of the conical configuration of the end of the tube 20 is the ring nozzle heating by the upwardly emerging het air. If the ring nozzle

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ARff ο 2 3 2 ²¹ is net heated disturbances can occur on exit of the sheet strips from the nozzle gap.

Claims (5)

a. tne cuter surfaces of tne s.-.ee: are termer by t-r relative!'.· gas-mperm eerie, i n particular a _ri aresealed cover layers; b; beeween tr.e cover layers mere is a layer oi spongy structure; and c; t.te layer includes a ply oi lenticular cas-iilled cavities with s da gey, furrowed and/or torn surface.

1?. A met.nod accoromg to claim 7, w.-.erein propellant cr gas-developing cnemicals such as sodium hydrcg^ncarccnate. ammonium hydrogencarccnate cr tne like is added to tne raw

- s c <q

21. An apparatus do .Γ*. ρ£Γ*£ΐΟ’*-Ι±οΙΓ ΙΟΓ y- Σ’ ΞΓ.ϊ/cr m parcicolar c .am an ext producing a tobacco-containing sneet. using a sneet according to claim 1 or carrying cut the method accorcmg

1. A s.teet according to clam 1, '-herein tne proportion cf tooacoo particles makes up ao least accut 35-55 a by weigr.t, m particular ao least about 52 % by weight, witr. respect to the total mass without water.

;2. .An apparatus according to claim 20, wherein tne nozzle

22. .An apparatus according to claim 20, wherein tne nozzle is provided with cutter blades, cutter pins cr the like.

24. An apparatus according to claim 20, wherein the gapforming parts of the nozzle are intermittently or permanently displaced or turned with respect to each other.

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AP Ο Ο Ο 2 3 2

25. .An apparatus according tc claim 23, -herein with a ring nozzle tne cuter and inner parts are rctatazle wicn respect tc eac.n other via a ball bearing.

26. An apparatus according tc claim 23, wherein the cap widen. is ad;ustacle via a sere-.

27. An apparatus according tc claim 20, wherein the expansion, chamcer is provided with at least one connection tor tne supply of hot gas, in particular not air.

23. An apparatus according tc claim 23, wherein the expansion c.n ameer is connected tc a neat source cf ad equate energy censity, for example an infrared radiator cr a hotcas generator.

29. An apparatus according to claim 20, wherein the expansion chancer has a tucular cross-section.

50. .An apparatus according to claim 20, wherein the expansion chancer is divided into two half-shell-like halves which are arranged on guide rails and adapted to be pushed apart.

51. .An apparatus according to claim 20, wherein m the interior cf the expansion chamber a hot-gas supply means is cisccsed.

52. An apparatus according to claim 27, wherein the connection fcr the supply of hot air surrounds the expansion chamber substantially an.nularly.

33. An apparatus according to claim 27, wherein the exit opening of the hoc-gas supply means and the exit opening of the hot-gas cr hot-gas supply means in the interior of the

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AP Ο Ο Ο 2 3 2

2 r. c z z 1 e , the nozzle is bellowed by a- expansion chamber through which tobacco sheet formed by the extruder is led: the expansion onamber is connected to a heat source m such a manner that the tocacoo sneet passing through tne expansion on ameer is m tensely heated from oo th sices so as tc form relatively gas-impermeable cover layers, and a spongy intermediate layer having bubbles and lenticular cavities.

21. .An apparatus according to claim 20, wherein the extruder is preceded by a mill for grinding large tccacco par tides .

3. A sheet according to clam 1, wherein the proportion of moisturizer makes up about 1 to about 6 % by weight, m 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.' 9’f?

expansion chamoer are so arranged that they Ib-e substantially opposite earn otner. '<

i-ι. .-_n apparatus acccrcmg to c_aim '«r.ers;

gas supply means m t.te icteric:

comprises a 1ance-scaped hot-gas supply means with a ccut.tpiece which in t.te longitudinal direction is i.t'-'erse' symmetrical tc the mcutnpiece c: the .tot-air supply means t.te .tot-gas 'et emitter by the net-gas supply means there: oei.ng substantially in lateral inverted symmetry with t.te he t-gas jet coming from the not-air supply means at the cuter penpnery ci t.te expansion c.tamcer, t.te tcoaccc s.tee representing t.te mirror surface cf t.te lateral inversion.

4. A sheet according to clam 1, wherein the binder is an acidic, neutral, basic and/or modified polysaccharide.

A sneet according to clam erem the cavities have an extent in sr.se ticxness of about 3.1 on - 5 mm and in sr.ee t wictn or a rout 3 mm.

mm to 13 ma. in pa ar i

5. A sneet according to thickness without taking cavities is about 0.1 to aa.

clam I, wherein the sheet account of the contribution of 0.4 ma, in particular 0.2 to 0

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ΑΡ 0 0 0 2 3 2 .3 - - e ra e ζ ο ζ γ. t e t h e f ο r η ι η ο pressure lues ret veer, scout 13 a n h 211 bar, preferably between 52 arc 113 oar; the tobacco sheet is strongly tea tec from both sties after the forming, suostantially gas-impermeaole cover layers thereby forming cn the tobacco sheet; ano by a further intense supply of heat the water cispcseo m the tobacco sheet between the cover layers evaporates, gas-filled lenticular cavities and gasfilled bubcles thereby being formed.

process stec.

9. A method according to claim 7, wherein one raw mass is pressed through a slot nozzle or a ring nozzle.

10. A method according to claim 7, wherein the cutters provided at the nozzle cut the emerging tooacco sneet into

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APO00232 3 strips which are in particular about 3 to 5 cm wide endless strips.

A metr.cd according to claim 7, wnerem the furt.ter u*

11. A metncc according to claim 7, wherein the further intense heat supply is effected by a medium cf suitable energy density such as infrared radiation, microwaves cr het gases.

13. A method according to claim 7, wnerem the hot air cr gas streams heat the tccacco sheet from both sides.

14. A method according to claim 7, wherein the heat supply is controlled so that the tobacco sheet product retains a residual moisture cf abcut 10 to 20 % (wet basis).

A method according to claim 7, wherein with an extruded hose-like tobacco sheet for the heat treatment method steps substantially the same hoc air or hot gas amounts are supplied within the expansion chamber both outside and inside the tobacco sheet.

15. A method according to claim 7, wherein the gap-forming parts of the nozzle are intermittently cr permanently displaced cr turned with respect to each ether.

17. A method according to claim 7, wherein the nozzle is intermittently cr permanently subjected to ultrasonic radiation .

13. A method according to claim 7, wherein the gasimpermeabilify of the cover layers is obtained by bilateral· application of thin layers to the tobacco sheet surface

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AP Ο Ο Ο 2 3 2 before said tobacco sheet is hear treated, λπ the expansion or. ameer.

:5. An apparatus according to claim £0, wherein to t.te ..-..ter part of the ring nozzle a tube is attached which is iisocsed central!·/ in t.te expansion c.tamcer.