|Publication number||US3870054 A|
|Publication date||Mar 11, 1975|
|Filing date||May 18, 1973|
|Priority date||May 19, 1972|
|Also published as||DE2324242A1, DE2324242B2|
|Publication number||US 3870054 A, US 3870054A, US-A-3870054, US3870054 A, US3870054A|
|Inventors||Arledter Hanns F, Marek Josef|
|Original Assignee||Austria Tabakwerke Ag|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (8), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
ite tates Arledter et a1.
ten [1 1' Mar. 11, 1975 1 METHOD OF MAKINGA LAMINATED TOBACCO FOIL  Inventors: Hanns F. Arledter, Graz; Josef Marek, Vienna, both of Austria 22 Filed: May 18, 1973 21 Appl. No.: 361,594
 Foreign Application Priority Data 3,015,895 1/1962 Stall 35/9 3,252,230 5/1966 Donev 3,654,706 4/1972 Perrella...
3,659,356 5/1972 Nelsonw. 3,802,965 4/1974 Arlcdter 162/303 Primary Examiner-Melvin D. Rein Attorney, Agent, or FirmKem0n, Palmer &
Estabrook  ABSTRACT A tobacco foil is made from at least two plies each comprising a film of predominantly reconstituted to bacco particles. Preferably, an intermediate layer of cellulose or comminuted tobacco ribs or porous inorganic materials is provided between the films. The intermediate layer may contain one or more active substances such as tobacco extract, burn control agents, ascorbic acid, magnesium perborate, odurants or flavourants. The films are precipitated from an aqueous suspension, combined and then dehydrated by pressing and thermal drying. Precipitation is carried out on a double sheet former comprising two endless screens which are inclined to one another in the sheetforming region.
22 Claims, 2 Drawing Figures PMENTED HARI 1 I975 SHEET 1 [IF 2 METHOD OF MAKING A LAMINATED TOBACCO FOIL The invention relates to tobacco foil.
it has already been variously proposed to produce tobacco foil by using the methods which are conventional in the paper industry, in that comminuted tobacco particles, particularly comminuted tobacco waste such as ribs or the like, are precipiated from an aqueous suspension onto a screen and subsequently pressed and dried. Since the requirement of making an adequately thin foil plays an important role with the known equipment and methods, it was considered obvious that the manufacture of the foils according to the method almost exclusively used in the paper industry should take place by one-sided filtering and pressing on the longitudinal screen ofa paper-making machine. Naturally, the resultant foil consisted ofa single layer of reconstituted tobacco particles.
As a basic departure from the procedures hitherto used in making tobacco foils, the present invention proposes to provide a tobacco foil comprising at least two separate films of reconstituted tobacco particles. The term reconstituted tobacco particles is intended to mean particles which, having regard to the components that are essential for smoking, substantially correspond to natural tobacco. They may be particles derived from tobacco plants the soluble components of which have been more or less replaced by treatment in an aqueous solution as is necessary for the formation of the foil-- or fibres which are not derived from tobacco plants but which are enriched by soluble active materials normally contained in tobacco plants so that they can replace the natural tobacco particles for smoking purposes.
The feature according to the present invention, which would at first sight appear to involve difficulties in attaining the requirements placed on a smokable foil, is surprisingly associated with decisive advantages not only with regard to the properties of the finished foil but also in connection with its manufacture.
First of. all, the invention makes it possible to introduce into the tobacco a number of materials that could hitherto be incorporated only partially or not at all.
For example, it is possible to provide between two films of reconstituted tobacco particles a cellulose layer which has been enriched with various substances. One can consider the aromatic components of a tobacco extract obtained from otherwise useless tobacco dust. The use of cellulose as a carrier material for this purpose makes it possible to exclude from the intermediate layer any undesired compounds such as brown pigments and other higher molecular substances. It is simply necessary to obtain a pore size for the cellulose, by suitably selecting, swelling and drying the cellulose, so that the cellulose acts as a molecular screen which only absorbs the desired substances, whereas the higher molecular substances remain at the surface and can be readily washed off.
The cellulose contains macropores having a diameter of 100 to 250 A and micropores with a diameter of 25 to 30 A. During swelling, 80 percent of the water is retained in the micropores and the remaining 20 percent in the macropores. When the fibres are dried under normal pressure, the macropore diameter irreversibly changes to 100 A. if drying of the fibres takes place in vacuum at moderate temperatures, the pores expand to 300 A. If a fibre that has already been swollen and is charged with various substances is dried, then these substances are irreversibly retained in the fibre (sees Stone, Sealand: Cellulose Chemistry and Technology, 2, 343 i968) Accordingly, readily volatile odourants such as menthol or other terpenoidic compounds, alkyl pyrazines, and fatty acid esters can be fixed in the cellulose. They are protected during drying by the two outer layers and are released only during combustion.
[f the combustion improving substances such as potassium nitrate which are usually contained in tobacco foils are introduced in the intermediate layer, the crackling which is otherwise brought about by such substances during burning of the tobacco is suppressed. in addition, the concentration of the tobacco improvers in a small portion of the tobacco prevents them from reducing the quality of the tobacco through gradual oxidation.'
More recent tests lead one to suspect that by means of ascorbic acid one can inhibit the formation of nitrous amine in tobacco smoke. Hitherto, however, there was no possibility of actually embodying this substance, which is sensitive to light and oxygen, in the tobacco despite the general suggestion that ascorbic acid should be used as a component for cigarettes. If ascorbic acid is introduced in the intermediate layer within the scope of the present invention, it is protected by the two outer layers and one obtains a tobacco giving a remarkably mild taste during smoking.
The incorporation of magnesium perborate in tobacco foils was hitherto also impossible because this substance is difficult to dissolve in water. In the intermediate layer between two films of reconstituted tobacco particles, this substance can be readily introduced as a suspension. When using elevated tempertures and in the simultaneous presence of water, this compound will then release oxygen to produce foaming and a looser structure for the foil.
It is of course also possible to introduce in the intermediate layer odourants or flavourants or threads improving the static properties of the foil, any or all of these being encapsulated in plastics pellets.
Since the intermediate layer is protected by the outer layers of the foil, it is possible to give it a particularly loose structure, which results in a lower surface weight, improved combustion and a reduction in the formation of smoke condensate. For example, a foil with an intermediate layer of only tobacco ribs exhibited a reduction in smoke condensate in the order of percent when compared with a cigarette of natural tobacco having the same weight. The incorporation of highly active diatomaceous earth or like compounds similarly results in loosening of the structure of the strip tobacco and hence better combustion and a better filling capacity of the smoking material. If these highly active adsorbents are exposed by perforating the strip tobacco, the filter effect of the unburnt tobacco stump is increased. The diatomaceous earth can also be charged with synthetic or natural aroma-producing substances.
Even without the use of an intermediate layer, the formation of a tobacco foil in accordance with the invention of more than one separate layer of reconstituted tobacco particles brings about surprising advantages. It may first of all be mentioned that by slight departures in the composition of the two films it is possible to produce considerable partial stresses in the foil if the foil segments or films are intimately interconnected even before drying and then dried together. This results in crimping of the tobacco particles cut from the foil, which enhances the filling capacity of the tobacco and facilitates its felting.
Above all, however, it should be noted that with foils according to the invention composed only of two layers of reconstituted tobacco a very marked improvement in practically all the important properties was found to occur, not only in comparison with natural tobacco but also when compared with the best foils available in the trade. This improvement affected practically all the decisive properties such as weight, resistance to drawing and the number of draws for cigarettes made from the foil, as well as the content of moist tar, dry tar, nicotine, benzo(a)pyrene and phenol. For this clearly evident effect there are two possible explanations, although it is emphasized that the theoretical investigations in this respect have not yet been concluded.
Firstly, it is found that foils made in the conventional manner by one-sided filtering on an elongated screen exhibit a one-sided concentration of very fine substances whereas the coarser fibres accumulate on the side facing the screen. With double-layer foils that have been tested, the films are interconnected in an oppositely directed arrangement so that the proportion of finer particles in the foil increases from the outside towards the centre. The manner of making foils according to the invention may be of even greater significance, according to which the films made entirely or predominantly of reconstituted tobacco particles are precipitated from an aqueous suspension on the two screens of a double sheet former that is basically known from the paper-making industry, are subsequently combined and then dehydrated together by thermal drying. Thus, where the present specification makes reference to two separate foil segments or films, this should not be understood to mean that the foil according to the invention must be made by combining two finished films. On the contrary, although the solid particles forming the two films or foil segments are precipitated on separate screens, it is preferred to combine them before drying.
Details of a preferred method according to the invention for making foils according to the invention, as well as a suitable apparatus for performing this method, will not be described with reference to the accompanying diagrammatic drawings in which:-
FIG. 1 is a diagram showing an entire foil-making apparatus, and
FIG. 2 is a side elevation of a preferred form of sheet former.
To ensure a uniform content of water-soluble substances in the end product, there is first of all a swelling apparatus for pretreating the starting material. Measured quantites of comminuted tobacco waste, particularly tobacco ribs but possibly also comminuted tobacco leaves, are fed to the swelling apparatus 5 by means of a belt balance 9. Heterogeneous cellulose for increasing the solidity of the finished foil is also introduced at this position.
The particles serving to form the foil must have a certain minimum size so that they are not rinsed away during formation of the foil. Thus, tobacco dust is only partially useful in so far that an extract is obtainable from its soluble parts. By adding such an extact, the reduction in the content of effective substances in the tinished foil caused by the addition of heterogeneous cellulose is compensated. It is preferred that the heterogeneous cellulose fed to the swelling apparatus 5 be already saturated with such an extract.
The principal component of the swelling apparatus 5 is a worm 7 which conveys the material whilst it is being enriched with liquid coming from a supply conduit 6. Treating apparatus 1 provided downstream of the swelling apparatus 5 comprises a series of refiners 1]. l l, 11"Before the swollen tobacco stem particles are supplied to these, the quantity of liquid necessary for the wet treatment is supplied through a conduit 3 and mixed in by a tubular mixer 10. If more easily grindable tobacco portions, e.g. cut tobacco leaves (gebits) are also to be treated, they are preferably first fed to the last refiner ll".
Downstream of the refiners there is a further tubular mixer 10 which facilitates the addition of the considerable quantities of liquid necessary for forming the sheet. A subsequent nodule catcher l2 separates insufficiently treated components and leads them through the conduit 13 back to the previously described portion of the cycle. A sheet former 2 disposed downstream of the nodule catcher 12 is the really essential part of the apparatus. In the illustrated case, it comprises two moving screens 25 between which the reconstituted tobacco foil is formed from the deposited particles of two films. The application of the films to the screens 25 takes place within a closed liquid chamber formed on the one hand by the liquid in the vessel constituted by the screens 25 and on the other hand by the liquid in the screen and in suction boxes 22 disposed therebelow. By reason of the water pressure of 5 to 200 centimetres of water column existing in the sheet-forming region of the screens, the sheet former can be referred to as a hydraulic double sheet former.
Excess liquid in the formation of the foil is withdrawn by a screen-suction dehydrator 22 and subsequently by sheet suction apparatus 20 connected to a vacuum pump 15. The liquid drawn off reaches the vessel 16, as does the liquid expressed by the suction presses l4 and the felt press 23. Preferably, Root pumps with air cooling are used for forming the vacuum and Hueber suction cylinders with suction shoes are used for dehydration by means of suction presses, so that no sealing water is used for the suction cylinders.
The vessel 16 constitutes the only intermediate reservoir in the entire cycle. lts volume is small compared with the total volume of liquid contained in the cycle. A dosing pump 17 delivers liquid from the vessel 16 into the swelling apparatus 5 through the conduit 6. Whilst the swelling apparatus 5 could be disposed outside the cycle of the liquid mechanically separated during formation of the foil, it is important that the treating apparatus 1 and the sheet former 2 be fed with this liquid. This takes place by means of the dosing pump 17' and conduit 3 as well as through the dosing pump 17" and a conduit 4 that is provided with a flow meter 19 and cooling means 18. The cooling means 18 serves to keep the cycled liquid to temperatures below 15C or 10C so as to suppress the uncontrolled growth of fungi and bacteria. The amount of liquid required prior to formation of the sheet for the purpose of thinning the material can be kept small by cycling it at least six times per minute.
For the further treatment of the mechanically dehydrated foil there are thermal driers and cutting apparatus (not shown). Screen cleaning equipment is also not illustrated. For the purpose of cleaning the screens one can use combinaations of suction and compressed air pipes for removing 95 percent of the juice, whereupon the solution on the screen is diluted by a small quantity of water (30 g/m with the aid of vaporising nozzles, and further liquid is removed from the screens with the aid of tubular suckers so that the proportion ofjuice is reduced to 0.1 percent. The screens which are now pratically free from solution are cleansed under high pressure, any solid screen deposits are freed once during each 2 minutes of the cycle by a minimum of fresh water which may be cycled, and, before they return to the box of substance, are again subjected to compressed air or tubular suckers to free them from fresh water.
The function of the apparatus illustrated in FIG. l in the formation of the sheet will first of all be described in general terms, followed by a numerical example.
The heterogeneous cellulose or heterogeneous fibrous substance of a crimped nature in an air-dried form is saturated with concentrated tobacco solution (e.g. dust extract) of, say, to 50 percent until an optimum quantity of liquid has been absorbed. This not only introduces water to the fibres but also the low molecular aroma and odourant parts of the tobacco plant. An airdried cellulose fibre contains, for example, pores of 300 A diameter and all low molecular proportions with particle sizes of less than 300 A can penetrate into the fibre with the water during swelling.
The raw materials of tobacco, such as ribs, leaves, stems, gebits etc. already contain up to 50 percent of water-soluble substances. These water-soluble substances should, as far as is possible, be retained in the solid particles during reconstitution of the foil. Although the dry ribs etc, should be swollen before they are disintegrated so as to regulate an optimum particle size and fibre length for the formation of the sheet, swelling does not serve the purpose of extracting the soluble substances as is usual with known methods. On the contrary, swelling is intended even to increase the content of soluble substances in the particles beyond the original value that is substantially the same as that of the insoluble solid substances of the fibres.
Swelling of the tobacco ribs (e.g., l kilogramme) and tobacco waste prior to grinding therefore takes place in about four to five times the quantity by weight of tobacco extract solution of 25 to 50 percent concentration during an absorption of liquid up to 150 to 250 percent, it being possible to use a separate swelling cycle (not illustrated) to add so much enriched water as is carried away by the swollen ribs.
The swollen ribs etc., which have an increased content of soluble components of up to 66 percent compared with their original proportion of solids, are now ground for 3 to minutes in the concentrated tobacco extract solution which is used in the entire cycle and which comprises, say, 20 to 30 percent dry content (200 to 300 g soluble'extracts per litre) until the size of the solid particles and the fibre length meet the requirements of sheet formation, the solid content of the fibres (proportion of the raw material that is insoluble in water) then being 2 to 6 percent. The proportion of soluble components in the swollen particles is still about 40 percent in this phase.
This ground suspension of fibrous substance is now diluted withthe screen water of the screen water cycle of the paper machine (which screen water likewise contains 200 to 300 g/l of soluble components) to a solid fibre content (insouble proportion) of 0.2 to 0.4 percent, is fed to the charge for the paper machine, and within a period of ID to 30 seconds a tobacco foil sheet is formed having a sheet weight for the insoluble foil proportions of 30 to 50 g/m. A. proportion of liquid remaining in the fleece is small, i.e. the dissolved substances are predominantly contained in the swollen particles.
Liquid is now withdrawn in known manner from the fibre fleece in the wet press of the paper-making machine by screens, felt, pressure and vacuum up to a dry content of 25 to 40 percent. After pressing, one obtains a wet tobacco foil that may have the following composition 25 percent 40 g/m" solid foil components which are insoluble in water percent 120 g/m liquid with 27% of soluble solids l60g/m wet foil.
This wet foil is subjected to thermal drying and, after vaporisation of the desired proportion of water, one is left with a dry tobacco foil tht may have the following composition 44.8 percent g/m foil components which are insoluble in water (atro) 39.6 percent 32.5 g/m foil components (atro) which are insoluble in water 1 1.6 percent 9.5 g/m water 100.0 percent 82.0 glm For each 82 kilogramme of finished foil only 78 kilogrammes of water (or rather 49 percent dry content) have to be vaporised.
It is therefore characteristic of the function of the illustrated apparatus that the concentrataion of the solution during sheet formation is so adapted with liquid extraction after sheet formation that the resulting dried tobacco foil contains the desired proportion of soluble solids.
The extraction of liquid can be kept constant by pressing before drying, leaving the desired concentration of solid substances in the sheet-forming suspension to adjust itself in the cycle as regulated by the supply of raw material.
The apparatus operates without any loss in extractable substances. After about 30 to 40 minutes of enriching the water to contain about 20 percent of extract upon commencement of production, the water extractable content of the foil is stabilised and remains constant.
It is also recommended that the 15 to 20 percent tobacco solutions are obtained prior to the continuous tobacco foil production by swelling and pressing the raw tobacco substances so that no enriching of the solution will be necessary during commencement of foil formation.
In a practical operating range with a proportion of weight of liquid in the foil of 75 to 80 percent after pressing there is obtained, with a concentration of the suspension of 20 to 25 percent, a proportion by weight of soluble substances in the tobacco foil of about 40 to 50 percent, which corresponds to the natural proportion.
lf treatment of the substance is continuous, the total amount of substance and liquid in the cycle can be reduced to 400 to 600 kg for a daily production of (12,000 kilogrammes) with 20,000 to 24,000 kg of water being evaporated, so that, theoretically, the liq-- uid in the cycle is renewed every 2 to 4 hours.
EXAMPLE 1 A reconstituted tobacco foil of 44 parts by weight Winnowa ribs, 36 parts by weight of gebits tobacco waste, eight parts by weight of cellulose fibres, 2 percent diglycol, 2 percent carboxymethylcellulose, two parts by weight of Mg citrate, 0.4 percent deactivator and 5.6 kilogramme tobacco dust is made as follows.
The tobacco dust is extracted in a countercurrent process at 40C and a 25 percent concentrate is made which is stored in a vessel.
The ribs (2.2 kg/min) and cellulose presaturated with dust'extract (0.4 kg/min) are continuously charged with the aid of an automatic proportioner in a volume of 120 l to a swelling apparatus 5 which is filled with an enriched solution of concentrate at 50C, and allows the ribs and the cellulose to swell for about one hour. The swollen solution is at this time pumped in countercurrent. The 2.6 kg ribs and cellulose absorb about 5.2 kg/min of solution during this hour, which solution is replenished with cycled solution by means of the dosing pump 17.
The ribs and cellulose in the swollen condition are now diluted from 65 kg per minute of cycled concentrate by means of the dosing pump 17 and flow continuously to the refiners ll, 11, 11" for treating the sub- 1 stance. 1.8 kg of gebits waste is also added at this stage.
After grinding of the ribs and cellulose, the suspension containing about 2 percent of solid substance is fed to the tubular mixer 10' which is simultaneously fed with 90 llmin of cycled concentrate with the aid of the dosing pump 17". Further, from a mixing container (not shown) one adds with the aid of a closing pump 3 litres per minute of a solution of concentrate containing 0.02 kg/min deactivator, 0.1 kg/min diglycol, 0.1 kg/min Mg citrate and 0.1 kg/min CMC.
The unified suspensions of substance are fed with a fibre-solid density of 0.5 percent through the nodule catcher 12 to the charge for the formation of the sheet.
To retain the fine fibrous substances, a filter layer is first formed in the upper screen portion of the sheet former 2, by which the fine fibrous substances can then be better and more completely retained in the second sheet-forming portion.
Dehydration of the foil to 20 to 35 percent of solid content takes place in the lower double screen portion with the aid of a felt press. 5 kg tobacco foil solids (atro) with a fibre-solid content of 2.5 kg/min (atro) are separated from the screen per minute.
The paper-making machine of 1 metre screen width should produce 66 m of foil from every 187 g/m and therefore runs with a screen speed of 66 m/min.
The foil is fed to the thermal drying section at a fibre consistency of 20 percent. The concentration of screen water amounts to 20 percent.
Fibrous substances 38 g/m' (atro) Soluble substances 38 g/m (atro) Proportion of Water 152 g/m Wet Foil 228 g/m The dried foil consists of 38 g/m fibrous substances 43.7%
38 g/m' soluble substances 43.7%
11 g/m' water 12.6%
1.60 kg of water must be evaporated for each kg of tobacco foil that is produced.
After moderate craping drying takes place by 5 to 15 percent at a high frequency of 27 MHz, assisted by hot air to remove the clouds of steam and by infra-red radiation drying. High frequency drying gives a very uniform depositing of the extracts in and on the solids without migration. The loss of odourants and aroma substances is small.
The permanence of craping the finished foil increases with the addition of strengthening binders (CMC).
EXAMPLE 2 The advantages of forming tobacco foils in the manner described in Example 1 are evident from a comparative test in which natural tobacco and foils made in the conventional manner on elongated screens are compared with a foil according to the present invention. The cigarettes that were tested were in each case without filter, had a length of mm and a diameter of 8.02 mm. In the production of the foils or the cut tobacco use was in every case made of the same mixture of 40 percent European Blend, 40 percent Virginia and 20 percent Burley. The cigarettes wer smoked to a butt length of 23 mm in accordance with the CORESTA standard. The results are shown in the following Table.
In a further test, cigarettes selected for the same draw resistance made from natural tobacco or conventional foils or foils according to the invention were found to have phenol contents in the smoke of 139 y per cigarette, 62.5 7 per cigarette, 31 'y per cigarette, respectively, which again demonstrates the superiority of foils according to the invention.
The foregoing description concerned a foil composed of two layers or films. How one can form a foil from several layers will now be described with reference to FIG. 2 in which the same reference numerals are employed for parts which are equivalent to those illustrated in FIG. 1. The FIG. 2 embodiment differs from the double sheet form in FIG. I particularly by the provision of separating walls 26 which sub-divide the space above the screens 25 so that, upon supplying differently composed solutions or suspensions through the conduits 27, multi-layer foils are deposited on the screens 25.
FIG. 2 also indicates a cycle 28 for very fine particles estabalished by the suction box 22 through the pump P. This cycle serves to reintroduce to the suspension above the screen 25 those small particles which could not yet be retained by the screen in the upper sheetforming region. Reintroduction is effected preferably considerably below the liquid level as determinend by overflows 29, desirably in the immediate vicinity of where the two films deposited on the inclined screen portions come together, at which position the material for forming a middle layer is also introduced through a hollow wall 30. The sheet suckers and suction cylinders 14 are preferably so powerful that the mechanical dehydration of the combined films takes place exclusively in the region where the screens run parallel to one another.
The serpentine path followed by the tobacco foil is brought about in that the sheet is alternately sucked or pressed towards one screen and then released therefrom by suction or compressed air and pressed or sucked against the other screen so that the screens are kept free from solid particles.
1. A method of making reconstituted tobacco foil comprising at least two separate films containing principally tobacco particles which comprises? providing an aqueous suspension of tobacco particles by swelling comminuted tobacco particles or iibers, subsequently grinding same and finally diluting same with water to form an aqueous suspension containing about 0.2 to 0.4 percent insoluble solids,
forming two separate wet sheets of tobacco particles by precipitating tobacco particles from said aqueous suspension onto foraminous webs,
combining together the resulting two wet sheets in proximate face to face relationship,
dehydrating the combined sheets by pressing, and
thermally drying the combined pressed sheets.
2. The method of claim 1 wherein said separate sheets as formed have an asymmetric distribution of particles relative to the cross-section of the sheets with the proportion of finer particles increasing from one side of the sheets to the other and said sheets are interconnected in an oppositely-directed arrangement so that in the combined sheets, the proportion of finer particles increases from the outside toward the inside thereof.
3. A reconstituted tobacco foil of asymmetric crosssection prepared by the process of claim 2.
4. The method of claim 1 wherein carboxymethylcellulose is added to said aqueous suspension as a binder which causes stiffening of said sheets upon thermal drying.
5. The method of claim 1 wherein the compositions of said two sheets differ from one another.
6. A method according to claim 1 wherein the combined wet sheets are creped 5 to 15 percent before the thermal drying.
7. The method of claim 1 wherein an intermediate layer is interposed between said two wet sheets when they are combined.
8. The method according to claim 7 wherein the intermediate layer comprises cellulose fibers.
9. The method according to claim 8 wherein the cellulose is combined with tobacco extract.
10. The method according to claim 7 wherein the intermediate layer includes combustion enhancers.
11. The method according to claim 10 wherein the combustion enhancer is potassium nitrate.
12. The method according to claim 7 wherein the intermediate layer contains about 2.5 percent ascorbic acid based on the weight of the layer.
13. The method according to claim 7 wherein the intermediate layer contains magnesium perborate.
14. The method according to claim 7 wherein the intermediate layer contains odourants or flavourants encapsulated in plastic pellets.
15. The method according to claim 17 wherein the intermediate layer contains filaments of plastic material.
16. The method according to claim 15 wherein the filaments are of polyethylene.
17. The method according to claim 7 wherein the intermediate layer contains threads of an inorganic material.
18. The method according to claim 17 wherein the inorganic material is glass.
19. The method according to claim 7 wherein the apparent density of the intermediate layer is less than that of the surrounding films of reconstituted tobacco particles.
20. The method according to claim 19 wherein the intermediate layer consists predominantly of comminuted tobacco ribs or crushed cellulose.
21. The method according to claim 19 wherein the intermediate layer consists predominantly of porous inorganic materials.
22. The method according to claim 21 wherein the intermediate layer comprises diatomaceous earth.
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|International Classification||A24B3/00, A24B15/12, A24B3/14, A24B15/00|
|Cooperative Classification||A24B3/14, A24B15/12|
|European Classification||A24B3/14, A24B15/12|