WO2019086412A1

WO2019086412A1 - Method for producing a bobbin of a sheet of a material containing alkaloids and bobbin comprising the same

Info

Publication number: WO2019086412A1
Application number: PCT/EP2018/079642
Authority: WO
Inventors: Rui Nuno BATISTA; Antoine ZUEND
Original assignee: Philip Morris Products S.A.
Priority date: 2017-10-31
Filing date: 2018-10-30
Publication date: 2019-05-09

Abstract

The present invention relates to a method for producing a bobbin, the method comprising the steps of: - providing a continuous sheet of a material containing alkaloids having a first free surface and a second free surface; - applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids to form an antisticking continuous sheet; - feeding said antisticking continuous sheet to a rotatable center core; and - rotating the rotatable center core so as to wind the antisticking continuous sheet around it in such a way to form a bobbin.

Description

METHOD FOR PRODUCING A BOBBIN OF A SHEET OF A MATERIAL CONTAINING ALKALOIDS AND BOBBIN COMPRISING

THE SAME

The present invention is related to a method for producing a bobbin of a sheet of a material containing alkaloids, such as homogenized tobacco material, and including an antisticking material.

Today, in the manufacture of tobacco products, besides tobacco leaves, also homogenized tobacco material is used. This homogenized tobacco material is typically manufactured from parts of the tobacco plant that are less suited for the production of cut filler, like, for example, tobacco stems or tobacco dust. Typically, tobacco dust is created as a side product during the handling of the tobacco leaves during manufacture.

The starting material for the production of homogenized tobacco material for aerosol-generating article may also be mostly tobacco leaves that have thus the same size and physical properties as the tobacco for the blending of cut filler.

Possible forms of homogenized tobacco material include reconstituted tobacco sheet and cast leaf. The process to form homogenized tobacco material sheets commonly comprises a step in which ground tobacco and a binder are mixed to form a slurry. The slurry is then used to create a tobacco web or sheet, for example by casting a viscous slurry onto a moving metal belt to produce so called cast leaf. Alternatively, a slurry with low viscosity and high water content can be used to create reconstituted tobacco in a process that resembles paper-making. The sheet or web of homogenized tobacco material is then rolled in bobbins which need to be unwound in order to be further processed and included in the aerosol-forming substrate of the aerosol-forming article.

Unwinding such bobbins can be however a difficult task. The homogenized tobacco material sheet, when coiled in bobbins, may be indeed difficult to unwind due to its consistency, sensitivity to heat, stickiness and low tensile strength : it could easily be torn apart and, if too high tensile strength is used to un-stuck the sheets, the sheets could break.

Furthermore, these bobbins may be difficult to transport and are furthermore currently consumed within a very short timeframe, since otherwise the sheets of homogenized tobacco materials bond together and quite definitively compromise unwinding. Consequently, building up a safety-stock of such bobbins can be a difficult task as well.

There is therefore a need of a method for producing a bobbin from a sheet of material containing alkaloids, such as homogenized tobacco material, that is easily unwound from a bobbin into which is stored and transported, and that therefore allows providing a continuous, constant and regular feed of material so that the rest of the production line can increase the overall production rate.

The invention may satisfy at least one of the above needs.

According to a first aspect, the invention relates to a method for producing a bobbin, the method comprising the steps of: providing a continuous sheet of a material containing alkaloids having a first free surface and a second free surface; applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids to form an antisticking continuous sheet; and winding the antisticking continuous sheet in a bobbin. In the method of the invention, an antisticking material is applied to a sheet including a material containing alkaloids. The antisticking material limits the stickiness of the sheet. The resulting sheet including the material containing alkaloids and the antisticking material may be wound up into a bobbin comprising a plurality of layers of said sheet one above the others. This bobbin may be easily unwound due to the low stickiness of the sheet including the antisticking material.

The unwinding of the sheet including the material containing alkaloids and the antisticking material or the feeding of the same into the production line is thus possibly facilitated.

As used herein, the term "sheet" denotes a laminar element having a width and length substantially greater than the thickness thereof. The width of a sheet is preferably greater than about 10 millimeters, more preferably greater than about 20 millimeters or about 30 millimeters. Even more preferably, the width of the sheet is comprised between about 100 millimeters and about 300 millimeters.

A "material containing alkaloids" is a material which contains one or more alkaloids. The alkaloids may comprise nicotine. The nicotine may be found, for example, in tobacco.

Alkaloids are a group of naturally occurring chemical compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure are also termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other elements such as chlorine, bromine, and phosphorus.

Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants, and animals. They can be purified from crude extracts of these organisms by acid-base extraction. Caffeine, nicotine, theobromine, atropine, tubocurarine are examples of alkaloids.

As used herein, the term "homogenised tobacco material" denotes material formed by agglomerating particulate tobacco, which contains the alkaloid nicotine. The material containing alkaloids can thus be a homogenised tobacco material.

The most commonly used forms of homogenized tobacco material is reconstituted tobacco sheet and cast leaf. The process to form homogenized tobacco material sheets commonly comprises a step in which tobacco dust and a binder, are mixed to form a slurry. The slurry is then used to create a tobacco web. For example by casting a viscous slurry onto a moving metal belt to produce so called cast leaf. Alternatively, a slurry with low viscosity and high water content can be used to create reconstituted tobacco in a process that resembles paper- making.

The sheet material of tobacco can be referred to as a reconstituted sheet material and formed using particulate tobacco (for example, reconstituted tobacco) or a tobacco particulate blend, a humectant and an aqueous solvent to form the tobacco composition. This tobacco composition may be then casted, extruded, rolled or pressed to form a sheet material from the tobacco composition. The sheet of tobacco can be formed utilizing a wet process, where tobacco fines are used to make a paper-like material; or a cast leaf process, where tobacco fines are mixed together with a binder material and cast onto a moving belt to form a sheet.

The sheet of homogenized tobacco material may be then rolled in bobbins which needs to be unwound in order to be further processed, to be part for example of an aerosol-forming article, that is to be included in the aerosol-forming substrate of the aerosol-forming article. In a "heat-not- burn" aerosol-generating article, an aerosol-forming substrate is heated to a relatively low temperature, in order to form an aerosol but prevent combustion of the tobacco material. Further, the tobacco present in the homogenized tobacco sheet is typically the only tobacco, or includes the majority of the tobacco, present in the homogenized tobacco material of such a "heat-not-burn" aerosol-generating article. This means that the aerosol composition that is generated by such a "heat-not-burn" aerosol- generating article is substantially only based on the homogenized tobacco material.

As used herein, the term "aerosol forming material" denotes a material that is capable of releasing volatile compounds upon heating to generate an aerosol. Tobacco, together with other compounds, may be classed as an aerosol forming material, particularly a sheet of homogenized tobacco comprising an aerosol former. An aerosol forming substrate may comprise or consist of an aerosol forming material.

The homogenized tobacco sheet generally includes, in addition to the tobacco, a binder and an aerosol-former, such as guar and glycerin. This composition leads to a sheet which may be "sticky", that is, it glues to adjacent objects, and at the same time it is rather fragile having a relatively low tensile strength.

Once a sheet of material containing alkaloids is produced, such as a sheet of homogenized tobacco material, it often needs to be stored at least for a certain time before it is further processed. In order to store it properly, without or with minimal risks of breakage or without occupying too much space, it is commonly wound into bobbins. However, winding the alkaloids containing sheet in a bobbin as such may create several problems in the subsequent unwinding, due to the "sticky" properties of the sheets. Due to the fact that the alkaloids containing sheet is sticky, the layers formed in the bobbin by the sheet wound in itself are prone to glue one onto the others, preventing unwinding.

In order to simplify the unwinding, or to anyhow produce a sheet of material which is relatively easy to handle, according to the invention a sheet including a material containing alkaloids and an antisticking material is provided .

In order to produce the sheet including a material containing alka loids and an antisticking material, a sheet including a material containing alkaloids is first provided . The sheet defines a first and a second surface, one opposite to the other.

An antisticking material is applied to the sheet including a material containing alkaloids in its first or in its second surface, or in both . The application of the antisticking material can be performed according to any method . The antisticking material may be sprayed, coated, brushed, on the sheet. The sheet itself may be immerged in the antisticking material .

The antisticking material may cover the whole first or second surface or only a portion thereof. It may also be present only in selected areas of the first or second surface, or in both .

The term "antisticking material" means a material which acts to prevent adhesion . Therefore, on a surface threated with an antisticking material, it is less probable that something adheres than on the same surface without the antisticking treatment.

By application of the antisticking material, a n antisticking continuous sheet is obtained . This antisticking continuous sheet is then wound into a bobbin, for example to be stored, or transported or used in other processing steps.

When this sheet including a material containing alkaloids and an antisticking material is coiled into a bobbin, the antisticking material acts limiting the stickiness of the sheet including a material containing alkaloid . In this way, the resulting bobbin comprises a plurality of windings of a sheet including a material containing al kaloids that do not stick together and may therefore be easily unwound . Preferably, the material containing alkaloids includes a homogenized tobacco material. Preferably, the material containing alkaloids may contain a single alkaloid, or more than a single alkaloid. Preferably, the alkaloids include tobacco. Preferably, the step of winding the antisticking continuous sheet into a bobbin includes: feeding the antisticking continuous sheet to a rotatable center core; and rotating the rotatable center core so as to wind the antisticking continuous sheet around it in such a way to form the bobbin. The bobbin is preferably formed attaching the antisticking continuous sheet to a center core, which may rotate around its axis. The center core during the rotation drags the continuous sheet and wraps it around itself in multiple windings. The bobbin is thus formed while rotating the rotatable center core.

Preferably, the antisticking continuous sheet is fed to the rotatable center core at a speed between about 10 meters/minute and about 500 meters/minute. In this way, the method of the invention may also be used for producing a bobbin comprising a plurality of windings of a sheet including a material containing alkaloids and an antisticking material.

Preferably, the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises applying an antisticking material on the whole first or the whole second surface of the continuous sheet of a material containing alkaloids. Preferably, the whole first or second surface of the continuous sheet of a material containing alkaloids is covered by the antisticking material, to avoid areas where the surface can still "glue" on other objects.

Preferably, the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises applying an antisticking material on both first and second free surface of the continuous sheet of a material containing alkaloids. The treatment of both surfaces of the antisticking continuous sheet may be preferred when both first and second surfaces of the sheet may come into contact with other objects, such as in the winding of the antisticking continuous sheet in a bobbin where the sheet forms windings, each of which is interposed between a lower and an upper winding.

Preferably, the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises depositing a coating layer of an antisticking material at least on one of the first and second free surface. It is preferred to add the antisticking agent as an outside layer rather than impregnating the continuous sheet of a material containing alkaloids. Impregnating the continuous sheet of a material containing alkaloids may be rather cumbersome due to the sheet's dimensions and fragility. This deposition process also minimizes possible interactions, such as chemical reactions, among the antisticking material and other components of the continuous sheet of a material containing alkaloids.

More preferably, the coating layer of an antisticking material has a thickness comprised between about 5 micron and about 20 micron. More preferably, the coating layer of an antisticking material has a thickness comprised between about 5 micron and about 15 micron. Even more preferably, it has a thickness of about 7 micron.

The thickness of the coating layer of an antisticking material depends on the minimum layer for which an antisticking effect is achieved and on the desired overall thickness of the sheet. The overall thickness of the sheet may influence the smoking experience of the user and therefore it may be a relevant factor. Further, the thickness of the coating layer of an antisticking material may depend on the speed of the sheet during for example casting, because it influences the speed of the devices used to realize the coating layer.

Preferably, the antisticking material comprises a component selected from the group consisting of a lubricant agent, a flavoring agent, a coating agent, or an antifoaming agent.

More preferably, the lubricant agent is selected from the group consisting of talc, sod ium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

More preferably, the coating agent is selected from the group consisting of sodium starch, hydroxypropyl methylcellulose phthalate, glyceryl behenate, glyceryl monostearate, calcium stearate, ethyl cellulose, cellulose acetate phthalate, ethyl acetate or a mixture thereof.

More preferably, the antifoaming agent is dimethicone.

The antisticking material and compounds are preferably selected among those listed and a pproved as additives for Food & Beverage and Pharma industries as neutral expedients additives, preferably also as inactive ingredients. Preferably the antisticking material can be applied in aqueous forms within several dilution ratios depending of the type of application . Even more preferably, the antisticking materials are selected among those which are cellulose based . Indeed, when the material containing alkaloids comprises cel lulose fibers there is a natural compatibility of those ingredients in many ways, including chemical stabi lity during, and after, drying .

Preferably, the antisticking material is applied in powder form, in liquid form or in slurry form .

Preferably, the antisticking material is in na no-encapsulated and/or in micro-encapsulated form . The antisticking material in nano-encapsulated and/or micro-encapsulated form can be designed in a way that it degrades in a defined predictable way only under certain conditions, and therefore it releases its content only when such conditions are met. By way of example, an antisticking material in nano-encapsulated and/or micro-encapsulated form may comprise a capsule material that is sensitive to temperature, and/or humidity. In this way, the antisticking material in nano-encapsulated and/or micro-encapsulated form may release its content when the environmental temperature, and/or humidity, is/are above a certain defined value(s). This can be particularly useful when adverse environmental conditions are present that may directly promote stickiness, and therefore avoiding or preventing such stickiness is desired.

An antisticking material in nano-encapsulated and/or micro-encapsulated form may comprise a capsule material that is degradable in a certain defined predictable time, for example when exposed to the material containing alkaloids. In this way, the antisticking material in nano- encapsulated and/or micro-encapsulated form would release its content at a defined rate. This can be particularly useful in order to create a defined time delay effect of the release of the antisticking material independently of other factors, knowing that the stickiness problem only occurs after a certain time, and therefore releasing the antisticking material only when it is expected that the stickiness problem may occur. This delay may avoid or prevent potential problems of an early contact of the antisticking material with the material containing alkaloids, namely potential migration over time of the antisticking material to the interior of the material containing alkaloids, instead of remaining on its surfaces, and therefore causing inefficiencies in the antisticking effect on the surface of the material.

According to a second aspect, the invention relates to a bobbin comprising a plurality of windings of a coated continuous sheet of a material containing alkaloids, wherein said coated continuous sheet of a material containing alkaloids comprises a layer of a material containing alkaloids and a coating layer of an antisticking material on the layer of a material containing alkaloids. The advantages of this bobbin have been already outlined with reference to the above method according to the invention and are not repeated herewith.

The bobbin shape can be any. It can have a substantially cylindrical shape, however an oval or anyhow deformed shape, such as a bobbin with bulges deforming a underlying cylindrical shape, does not hinder the application of the teaching of the invention.

Preferably, the coating layer of the antisticking material has a thickness comprised between about 5 micron and about 20 micron. More preferably, the coating layer of the antisticking material has a thickness comprised between about 5 micron and about 15 micron. Even more preferably, it has a thickness of about 7 micron.

Preferably, the antisticking material comprises a component selected from the group consisting of a lubricant agent, a flavoring agent, a coating agent, or an antifoaming agent. More preferably, the lubricant agent is selected from the group consisting of talc, sodium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

More preferably, the antifoaming agent is dimethicone. According to a third aspect, the invention relates to a method for producing an aerosol generating article including a material containing alkaloids, the method comprising the step of unwinding the bobbin realized according to the second aspect. Aerosol forming articles according to the present invention may be in the form of filter cigarettes or other smoking articles in which tobacco material is combusted to form smoke. The present invention additionally encompasses articles in which tobacco material is heated to form an aerosol, rather than combusted, and articles in which a nicotine- containing aerosol is generated from a tobacco material without combustion or heating.

Aerosol forming articles according to the invention may be whole, assembled aerosol forming articles or components of aerosol forming articles that are combined with one or more other components in order to provide an assembled article for producing an aerosol, such as for example, the consumable part of a heated smoking device.

An aerosol forming article may be an article that generates an aerosol that is directly inhalable into a user's lungs through the user's mouth. An aerosol forming article may resemble a conventional smoking article, such as a cigarette and may comprise tobacco. An aerosol forming article may be disposable. An aerosol forming article may alternatively be partially-reusable and comprise a replenishable or replaceable aerosol forming substrate.

An aerosol forming article may also include a combustible cigarette. In preferred embodiments, the aerosol forming- article may be substantially cylindrical in shape. The aerosol forming article may be substantially elongated. The aerosol forming article may have a length and a circumference substantially perpendicular to the length. The aerosol forming article may have a total length between approximately about 30 millimeters and approximately about 100 millimeters. The aerosol forming article may have an external diameter between approximately about 5 millimeters and approximately about 12 millimeters.

In all the aspects of the invention, preferably, the sheet including a material containing alkaloids is a homogenized tobacco sheet, where the material containing alkaloids is tobacco containing nicotine.

Preferably, the homogenized tobacco sheet is obtained casting a slurry.

The homogenized tobacco sheet includes tobacco particles grinded from tobacco leaves (for example tobacco stem and lamina). The homogenized tobacco sheet may also comprise a minor quantity of one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco.

The tobacco present in the homogenized tobacco material may constitute the majority of the tobacco, or even substantially the total amount of tobacco present in the aerosol-generating article. The impact on the characteristics of the aerosol, such as its flavour, may derive predominantly from the homogenized tobacco material. It is preferred that the release of substances from the tobacco present in the homogenized tobacco material is simplified, in order to optimize use of tobacco. In the following, the term "tobacco particles" is used through the specification to indicate tobacco having a mean size per weight between about 0.03 millimetres and about 0.12 millimetres.

Tobacco particles having a mean particle size by weight between about 0.03 millimetres and about 0.12 millimetres may improve the homogeneity of the slurry. The quantity of binder added to the blend of one or more tobacco types is comprised between about 1 percent and about 5 percent in dry weight of the slurry. The binder used in the slurry may be any of the gums or pectins described herein. The binder may ensure that the tobacco powder remains substantially dispersed throughout the homogenized tobacco web. For a descriptive review of gums, see Gums And Stabilizers For The Food Industry, IRL Press (G.O. Phillip et al. eds. 1988); Whistler, Industrial Gums: Polysaccharides And Their Derivatives, Academic Press (2d ed. 1973); and Lawrence, Natural Gums For Edible Purposes, Noyes Data Corp. (1976).

The homogenized tobacco material comprises preferably between about 45 percent and about 93 percent in dry weight basis of tobacco particles. Preferably, the homogenized tobacco sheet also includes a binder.

Although any binder may be employed, preferred binders are natural pectins, such as fruit, citrus or tobacco pectins; guar gums, such as hydroxyethyl guar and hydroxypropyl guar; locust bean gums, such as hydroxyethyl and hydroxypropyl locust bean gum; alginate; starches, such as modified or derivitized starches; celluloses, such as methyl, ethyl, ethylhydroxymethyl and carboxymethyl cellulose; tamarind gum; dextran; pullalon; konjac flour; xanthan gum and the like. The particularly preferred binder for use in the present invention is guar.

Preferably, binder is in an amount comprised between about 1 percent and about 5 percent in dry weight basis of the homogenized tobacco sheet. More preferably, it is comprised between about 2 percent and about 4 percent.

Preferably, the homogenized tobacco sheet also includes cellulose fibers, in addition to the cellulose fibers already present in the tobacco. Cellulose fibres may be introduced in the slurry. The introduction of cellulose fibres in the slurry typically increases the tensile strength of the tobacco material web, acting as a strengthening agent. Therefore, adding cellulose fibres may increase the resilience of the homogenized tobacco material web.

Cellulose fibres for including in a slurry for homogenized tobacco material are known in the art and include, but are not limited to : soft-wood fibres, hard wood fibres, jute fibres, flax fibres, tobacco fibres and combination thereof. In addition to pulping, the cellulose fibres might be subjected to suitable processes such as refining, mechanical pulping, chemical pulping, bleaching, sulphate pulping and combination thereof.

Cellulose fibres may include tobacco stem materials, stalks or other tobacco plant material. Preferably, cellulose fibres such as wood fibres comprise a low lignin content. Alternatively fibres, such as vegetable fibres, may be used either with the above fibres or in the alternative, including hemp and bamboo.

The length of cellulose fibres is advantageously between about 0.2 millimetres and about 4 millimetres. Preferably, the mean length per weight of the cellulose fibres is between about 1 millimetre and about 3 millimetres.

Further, preferably, the amount of the cellulose fibres is comprised between about 1 percent and about 7 percent in dry weight basis of the total weight of the slurry (or homogenized tobacco sheet). Advantageously, the method comprises the step of adding an aerosol- former to the slurry. Suitable aerosol-formers for inclusion in slurry for homogenised tobacco material are known in the art and include, but are not limited to : monohydric alcohols like menthol, polyhydric alcohols, such as triethylene glycol, 1,3-butanediol and glycerin; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Examples of preferred aerosol-formers are and propylene glycol. The homogenized tobacco material may have an aerosol-former content of greater than about 5 percent on a dry weight basis. The homogenized tobacco material may alternatively have an aerosol former content of between about 5 percent and about 30 percent by weight on a dry weight basis. More preferably, the aerosol-former is comprised between about 10 percent to about 25 percent of dry weight of the homogenized tobacco material. More preferably, the aerosol-former is comprised between about 15 percent to about 25 percent of dry weight of the homogenized tobacco material. The binder and the cellulose fibers are preferably included in a weight ratio comprised between about 1:7 and about 5:1. More preferably, the binder and the cellulose fibers are included in a weight ratio comprised between about 1:1 and about 3:1.

The binder and the aerosol-former are preferably included in a weight ratio comprised between about 1:30 and about 1:1. More preferably, the binder and the aerosol-former are included in a weight ratio comprised between about 1:20 and about 1:4.

The binder and the tobacco particles are preferably included in a weight ratio comprised between about 1:100 and about 1:10. More preferably, the binder and the tobacco particles are included in a weight ratio comprised between about 1:50 and about 1:15, even more preferably between about 1:30 and 1:20.

The aerosol-former and the tobacco particles are preferably included in a weight ratio comprised between about 1:20 and about 1:1. More preferably, the aerosol-former and the tobacco particles are included in a weight ratio comprised between about 1:6 and about 1:2.

The aerosol former and the cellulose fibres are preferably included in a weight ratio comprised between about 1:1 and about 30:1. More preferably, the aerosol-former and the cellulose fibres are included in a weight ratio comprised between about 5 : 1 and about 15 : 1.

The cellulose fibres and the tobacco particles are preferably included in a weight ratio comprised between about 1 : 100 and about 1 : 10. More preferably, the cellulose fibres and the tobacco particles are preferably included in a weight ratio comprised between about 1 : 50 and about 1 : 20.

The above mentioned weight ratios of the ingredients of the homogenized tobacco sheet are applicable not only to the homogenized tobacco sheet, but also they are the weight ratios of the various ingredients present in the slurry.

A web of homogenized tobacco material is preferably formed by a casting process of the type generally comprising casting a tobacco slurry onto a moving metal belt. Preferably, the cast web is dried to form a web of homogenized tobacco material and it is then removed from the support surface.

Specific embodiments of the invention will be further described, by way of example only, with reference to the accompanying drawings in which :

• Figure 1 shows a flow diagram of the method of the invention to produce a sheet including a material containing alkaloids and an antisticking material;

• Figure 2 is a lateral view of a bobbin of the invention; and

• Figure 3 is a lateral schematic view of an apparatus for producing the bobbin of the invention.

With initial reference to Figure 1, a method for the production of a sheet 305 including a material containing alkaloids and an antisticking material is represented. The first step 100 of the method of the invention is the provision of a sheet 300 including a material containing alkaloids (sheet visible in figure 3). This sheet may have a first moisture content. The sheet 300 preferably includes a homogenized tobacco material. Preferably, in step 100 the homogenized tobacco sheet 300 has preferably a first moisture content comprised from about 60 percent to about 80 percent in total weight basis of the homogenized tobacco sheet.

The method may include a further step 101 in which the homogenized tobacco sheet 300 is dried up to a second moisture content. Preferably, at the end of step 101 the homogenized tobacco sheet 300 has a moisture content comprised between from about 7 percent to about 15 percent in total weight basis of the homogenized tobacco sheet.

Further, the method of the invention includes a step 102 of applying an antisticking material to the homogenized tobacco sheet 300.

Preferably, the homogenized tobacco sheet 300 has a first free surface 306 and a second free surface 307 (see figure 3). In step 102, the antisticking material is applied either on the first free surface 306 of the homogenized tobacco sheet 300 or on the second free surface 307, or in both.

Preferably, in step 102 a coating layer 220 (see figure 2) including the antisticking material is applied. Preferably, the coating layer 220 has a thickness comprised between about 5 micron and about 20 micron. In this way, at the end of step 102 the antisticking continues homogenized tobacco sheet 305 including an antisticking material is obtained.

After the step 102 of applying an antisticking material, a further step 103 of feeding the homogenized tobacco sheet 305 including an antisticking material to a rotatable center core is performed.

After the step 103 of feeding to a rotatable center core the homogenized tobacco sheet 305 including an antisticking material, a further step 104 of rotating the rotatable center core is performed. In this way, the homogenized tobacco sheet 305 including an antisticking material is wound up to form a bobbin 200.

The homogenized tobacco sheet 305 wound in the bobbin 200 is depicted in figure 2 in a lateral view. Bobbin 200 comprises a plurality of windings 210 of a homogenized tobacco sheet 305 including an antisticking material.

In Fig. 3, a lateral schematic view of an apparatus 400 for carrying out the method of the invention to produce the bobbin 200 from the sheet 305 of a material containing alkaloids and including an antisticking material, from homogenized tobacco sheet 300, is shown. Sheet 300 has been already described with reference to figs. 1 and 2. Sheet 300 defines a first free surface 306 and a second free surface 307.

Preferably, but not necessarily, the apparatus puts in operation the method of the invention described with reference to figure 1. The apparatus 400 includes a conveyor belt 302, an applying device 303 and a drying device 304.

Conveyor belt 302 moves the sheet 300 including a material containing alkaloids and having a first moisture content along a transport direction (indicated by arrow 301) towards drying device 304. Sheet 300 is a homogenized tobacco material sheet having preferably the first moisture content comprised from about 60 percent to about 80 percent in total weight basis of the homogenized tobacco sheet.

Drying device 304 comprises an endless, stainless steel belt dryer including the conveyor belt 309 and a drying chamber 310. Conveyor belt 309 moves sheet 300 through drying chamber 310. In drying chamber 310 a drying flow of heated air flows on sheet 300. The drying flow of heated air removes moisture from sheet 300, thus lowering its moisture content up to the second moisture content, so that - downstream of drying device 304 - the sheet 300 has a second moisture content. Sheet 300 has preferably a second moisture content comprised between from about 7 percent to about 15 percent in total weight basis of the homogenized tobacco sheet.

Downstream of drying device 304, sheet 300 is moved towards applying device 303.

Applying device 303 includes three coating devices 408, 414 and 415. Coating devices 408 and 414 apply to first free surface 306 two coating layers each having a thickness of about 7 micron of an antisticking material.

Coating device 415 applies to second free surface 307 a coating layer having a thickness of about 7 micron of an antisticking material.

Therefore, downstream of coating devices 408, 414 and 415, a continuous sheet 305 of homogenized tobacco material having a second moisture content comprised between from about 7 percent to about 15 percent in total weight basis of the homogenized tobacco sheet and including an antisticking material is obtained.

Further apparatus 300 includes rollers 411 and a rotatable center core 412 positioned downstream the applying device 303 in the direction of motion of the sheet 305.

Continuous sheet 305 including an antisticking material is directed by roller 411 and fed to the rotatable center core 412.

Rotatable center core 412 rotates in the sense indicated by arrow 416, so continuous sheet 305 is wound around rotatable center core 412, forming the bobbin 200.

Claims

Method for producing a bobbin, the method comprising the steps of:

- providing a continuous sheet of a material containing alkaloids having a first free surface and a second free surface;

- applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids to form an antisticking continuous sheet; and

- winding the antisticking continuous sheet in a bobbin.

Method according to claim 1, wherein the step of winding the antisticking continuous sheet in a bobbin includes:

- feeding the antisticking continuous sheet to a rotatable center core; and

- rotating the rotatable center core so as to wind the antisticking continuous sheet around it in such a way to form the bobbin.

Method according to claim 1 or 2, wherein the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises applying an antisticking material on the whole first or the whole second surface of the continuous sheet of a material containing alkaloids.

Method according to any one of the preceding claims, wherein the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises applying an antisticking material on both first and second free surface of the continuous sheet of a material containing alkaloids.

Method according to any one of the preceding claims, wherein the step of applying an antisticking material on at least one of the first and second free surface of the continuous sheet of a material containing alkaloids comprises depositing a coating layer of an antisticking material at least on one of the first and second free surface.

Method according to claim 5, wherein the coating layer of an antisticking material has a thickness comprised between about 5 micron and about 20 micron.

Method according to any of the preceding claims, wherein the antisticking material comprises a component selected from the group consisting of a lubricant agent, a flavoring agent, a coating agent, or an antifoaming agent.

Method according to claim 7, wherein the lubricant agent is selected from the group consisting of talc, sodium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

Method according to claim 7 or 8, wherein the coating agent is selected from the group consisting of sodium starch, hydroxypropyl methylcellulose phthalate, glyceryl behenate, glyceryl monostearate, calcium stearate, ethyl cellulose, cellulose acetate phthalate, ethyl acetate or a mixture thereof. Method according to any one of claims from 7 to 9, wherein the antifoaming agent is dimethicone.

Method according to any one of the preceding claims, wherein the antisticking material is applied in powder form, in liquid form or in slurry form.

Method according to any one of the preceding claims, wherein the antisticking material is in nano-encapsulated and/or in micro-encapsulated form.

Bobbin comprising a plurality of windings of a coated continuous sheet of a material containing alkaloids, wherein said coated continuous sheet of a material containing alkaloids comprises a layer of a material containing alkaloids and a coating layer of an antisticking material on the layer of a material containing alkaloids.

14. Bobbin according to claim 13, wherein the coating layer of the antisticking material has a thickness comprised between about 5 micron and about 20 micron.

15. Bobbin according to claim 13 or 14, wherein the antisticking material comprises a component selected from the group consisting of a lubricant agent, a coating agent, a flavoring agent or an antifoaming agent.

16. Bobbin according to claim 15, wherein the lubricant agent is selected from the group consisting of talc, sodium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

17. Bobbin according to claim 15 or 16, wherein the coating agent is selected from the group consisting of sodium starch, hydroxypropyl methylcellulose phthalate, glyceryl behenate, glyceryl monostearate, calcium stearate, ethyl cellulose, cellulose acetate phthalate, ethyl acetate or a mixture thereof.

18. Bobbin according to any one of claims from 15 to 17, wherein the antifoaming agent is dimethicone.

19. Method for producing an aerosol generating article including a material containing alkaloids, the method comprising the step of unwinding the bobbin according to any one of claims from 13 to

18.