The present invention is related to a method for producing a multilayer coated sheet including a material containing alkaloids, such as homogenized tobacco material, and further including a first and a second coating of 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 windings, the sheet 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 sheet including a 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.

In an aspect, the invention relates to method for producing a multilayer coated sheet, the method comprising the steps of: providing a sheet including a material containing alkaloids, the sheet having a first free surface and a second free surface; applying on the first free surface of the sheet including a material containing alkaloids a first coating layer including a first antisticking material; and applying on the second free surface of the sheet including a material containing alkaloids a second coating layer including a second antisticking material .

Preferably, said first coating layer including an antisticking material has a thickness comprised between about 5 micron and about 20 micron. The sheet including a material containing alkaloids is per se sticky, due to the alkaloids material properties or the presence of sticking components in a slurry from which the sheet is cast. Therefore, a bobbin formation using the bare sheet could be problematic, because various coils of the sheet in a bobbin would stick one to the others. In the method of the invention, a first coating layer of a first antisticking material is applied to a first free surface of the sheet of a material containing alkaloids, and a second coating layer of a second antisticking material is applied to a second free surface of the same sheet. The antisticking material limits the intrinsic stickiness of the sheet and it is applied on both free surfaces of the sheet. The multilayer sheet may be wound up into a bobbin comprising a plurality of coils or windings of said sheet one above the others, which may be easily unwound due to the low stickiness of the surfaces in contact with each other.

The unwinding of the sheet including a material containing alkaloids or the feeding of the same to the production line is thus possibly facilitated.

As used herein, the term "sheet" denotes a laminar element having a length 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. As used herein, the term "coating" denotes a covering that is applied to the surface of an object. The coating may be an all-over coating, completely covering the substrate, in this case the free surface of the sheet onto which it is applied, or it may only cover parts of the same.

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 on ly 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, particu larly a sheet of homogenized tobacco comprising an aerosol former. An aerosol forming substrate may comprise or consist of an aerosol forming material .

The homogenized sheet containing alkaloids generally includes, in addition to the material containing alkaloids, such as 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 including material conta ining 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 brea kage 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 g lue one onto the others, preventing unwinding .

In order to sim plify the unwinding, or to anyhow produce a sheet of material which is relatively easy to handle, according to the invention a sheet of material containing alkaloids is provided . The sheet of material containing alkaloids may be obtained, for example by casting or extruding, from a slurry.

The sheet of material containing alkaloids is "sticky", that is, it glues to adjacent objects.

A first coating layer of a first antisticking material is then applied on a first free surface of the sheet. The coating application process can be realized according to any known process. For example, the first coating layer of a first antisticking material can be applied by depositing by pouring or spraying the first antisticking material on the first free surface of the sheet. The term "antisticking material" means a material which acts to prevent adhesion. Therefore, it is less probable that something adheres on a surface threated with an antisticking material, than on the same surface without the antisticking treatment. The coating layer of a first antisticking material may prevent adhesion between the first free surface of the sheet to adjacent objects. Therefore, by the application of a coating layer including a first antisticking material to a first free surface of the sheet, the latter is less prone to adhere to other elements or objects. A second coating layer of a second antisticking material is then applied to a second free surface of the sheet including a material containing alkaloids. In the method according to the invention, therefore, a second antisticking material is applied also to a second free surface of the sheet. The application of the second coating layer including a second antisticking material can be performed according to any method, which may be the same or different from the one used for applying the first coating layer.

Similarly to the coating layer including a first antisticking material, the coating layer including a second antisticking material may prevent adhesion of the second surface of the sheet to adjacent objects.

By application of a first and second coating layer including a first and second antisticking material, a multilayer sheet including a material containing alkaloids comprising a layer including a material containing alkaloids, the first coating layer including the first antisticking material and the second coating layer including the second antisticking material is therefore provided.

When this multilayer sheet is coiled into a bobbin, the first coating layers including the first antisticking material and the second coating layer including the second antisticking material are in contact and therefore the possibility that they "glue" together is rather limited. In this way, the multilayer sheet may be wound into a bobbin comprising a plurality of windings of a multilayer sheet including a material containing alkaloids that do not stick together and may therefore be easily unwound.

Preferably, the sheet including a material containing alkaloids has a thickness comprised between about 100 micron and about 300 micron and a width from between about 0.1 meters to about 2 meters. Preferably, the thickness of the sheet including a material containing alkaloids is the "standard" thickness used for the production of aerosol generating articles, for example of about 200 micron. There is no need of modifying standard process steps. Preferably, the first coating layer including the first antisticking material has a thickness comprised between about 5 micron and about 20 micron, more preferably between about 5 micron and aboutl5 micron, even more preferably comprised between about 6 micron and about 12 micron, even more preferably approximately of about 7 micron.

Preferably, the second coating layer including the second antisticking material has a thickness comprised between about 5 micron and about 20 micron, more preferably between about 5 micron and aboutl5 micron, even more preferably comprised between about 6 micron and about 12 micron, even more preferably approximately of about 7 micron.

The thickness of the first or the second coating layers including the first and second 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 first or the second antisticking coating layer 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.

The first and second coating layers including the first and second antisticking material may respectively and independently from each other cover the whole first and the whole second free surface of the sheet or only a portion thereof. Each or both of them may also respectively cover only selected areas of the first and second free surfaces.

In this way, the multilayer sheet including a material containing alkaloids has at least two "not-sticky" free surfaces and may therefore be wound up to form a bobbin without or with minimal risks of breakage during unwinding of the same.

The application of the first and second layer by coating is preferred to applying the layer by impregnating the sheet with an antisticking material, since an impregnating process may be rather cumbersome due to the sheet's dimensions and fragility. In addition, in this way it is also possible to minimize possible interactions, such as chemical reactions, among the antisticking material and other components of the sheet.

The first antisticking material may be different from or may be equal to the second antisticking material.

Preferably, at least one of the first and second antisticking material is selected from the group consisting of talc, sodium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

Preferably, at least one of the first and second antisticking material comprises a component 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.

Preferably, the at least one of the first and second antisticking material is dimethicone.

The antisticking material and compounds are preferably selected among those listed and approved 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 cellulose fibers there is a natural compatibility of those ingredients in many ways, including chemical stability during, and after, drying.

Preferably, at least one of the first and second antisticking material is applied in powder form, in liquid form or in slurry form.

Preferably, at least one of the first and second antisticking material in nano-encapsulated and/or micro-encapsulated form.

The antisticking material in nano-encapsulated and/or microencapsulated 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 microencapsulated 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 particu larly 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 microencapsulated 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 al kaloids, 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 .

Preferably, the material containing alkaloids includes a homogenized tobacco material . Preferably, the material containing alkaloids may contain a sing le alkaloid, or more than a sing le alka loid . Preferably, the alkaloids include tobacco.

Preferably, the sheet including a material containing a lkaloids is a continuous sheet. The sheet may be also indicated as a web. Preferably, the sheet including a material containing alkaloids has a moisture content comprised between from about 7 percent to about 15 percent in total weight basis of the sheet. At this moisture content, the sheet is substantially solid and relatively easy to handle. Preferably, the sheet including a material containing alkaloids comprises: particles of the material containing alkaloids having a mean size per weight comprised between about 0.03 millimetres and about 0.12 millimetres; a binder; and water.

Preferably, the sheet including the material containing alkaloids comprises from about 1 percent and about 5 percent in dry weight basis of the binder.

Preferably, the sheet including the material containing alkaloids comprises from about 45 percent and about 93 percent in dry weight basis of the particles of a material containing alkaloids. Preferably, the sheet including the material containing alkaloids comprises from about 1 percent to about 7 percent per weight on a dry weight basis of cellulose fibres, the cellulose fibres having a mean length comprised between about 0.2 millimetres and about 4 millimetres. Preferably, the sheet including the material containing alkaloids comprises between about 5 percent and about 30 percent in dry weight basis of an aerosol-former.

According to a second aspect, the invention relates to a multilayer coated sheet including a material containing alkaloids comprising a layer including a material containing alkaloids, a first coating layer including a first antisticking material and a second coating layer including a second antisticking material.

The advantages of this multilayer coated sheet have been already outlined with reference to the above method according to the invention and are not repeated herewith.

Preferably, in said multilayer coated sheet, the layer including a material containing alkaloids has a thickness comprised between about 100 micron and about 300 micron and a width from between about 0.1 meters to about 2 meters. Preferably, the thickness of the layer including a a material containing alkaloids is the "standard" thickness used for the production of aerosol generating articles, for example of about 200 micron. There is no need of modifying standard process steps.

Preferably, in said multilayer coated sheet said first coating layer has a thickness comprised between about 5 micron and about 20 micron, more preferably comprised between about 5 micron and about 15 micron, even more preferably comprised between about 6 micron and about 12 micron, even more preferably approximately of about 7 micron.

Preferably, in said multilayer coated sheet, said second coating layer has a thickness comprised between about 5 micron and about 20 micron, more preferably comprised between about 5 micron and about 15 micron, even more preferably comprised between about 6 micron and about 12 micron, even more preferably approximately of about 7 micron.

Preferably, in said multilayer coated sheet at least one of the first and second antisticking material is selected from the group consisting of talc, sodium stearyl fumarate, sodium benzoate, magnesium stearate, tobacco powder or a mixture thereof.

Preferably, in said multilayer coated sheet at least one of the first and second antisticking material 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.

Preferably, the at least one of the first and second antisticking material is dimethicone.

Preferably, the antisticking material which is used in said multilayer coated sheet is in nano-encapsulated and/or micro-encapsulated form.

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 layer of material containing alkaloids is a continuous layer.

Preferably, the multilayer coated sheet has a moisture content comprised between from about 7 percent to about 15 in total weight basis of the multilayer coated sheet. At this moisture content, the multilayer coated sheet is substantially solid and relatively easy to handle.

Preferably, in said multilayer coated sheet, the layer including a material containing alkaloids comprises: particles of a material containing alkaloids having a mean size per weight comprised between about 0.03 millimetres and about 0.12 millimetres; a binder; and water.

Preferably, said layer including a material containing alkaloids comprises from about 1 percent and about 5 percent in dry weight basis of the binder.

Preferably, said layer including a material containing alkaloids comprises from about 45 percent and about 93 percent in dry weight basis of the particles of a material containing alkaloids.

Preferably, said layer including a material containing alkaloids comprises from about 1 percent to about 7 percent per weight on a dry weight basis of cellulose fibres, the cellulose fibres having a mean length comprised between about 0.2 millimetres and about 4 millimetres.

Preferably, said multilayer coated sheet comprises between about 5 percent and about 30 percent in dry weight basis of an aerosol-former. Said multilayer coated sheet may be wound up into a bobbin comprising a plurality of layers of said multilayer coated sheet one above the others, which may be easily unwound due to the low stickiness of the sheet including said coating layers of antisticking material. 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.

According to a third aspect, the invention relates to an aerosol- generating article, comprising a component prepared from the multilayer coated sheet according to the second aspect of the invention or from the method according to the first aspect of the invention.

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 derivatized 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: softwood 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 glycerin 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 multilayer coated sheet including an antisticking material;

• Figure 2 is a lateral perspective view of a multilayer coated sheet of the invention; and

• Figure 3 is a lateral schematic view of an apparatus for carrying out the method of the invention to produce a multilayer coated sheet of the invention.

With initial reference to Figure 1 and 2, a method for the production of a multilayer coated sheet 200 (visible in figure 2) of the invention is represented. The first step 100 of the method of the invention is the provision of a sheet 210 of a material containing alkaloids having a first free surface and a second free surface. Material containing alkaloids to be used in the method of the invention preferably is a homogenized tobacco material. Preferably, in step 100 the homogenized tobacco sheet 210 has a thickness of between about 100 micron and about 300 micron and a width from between about 0.1 meters to about 2 meters.

The method includes a further step 101 in which a first coating later 220 of a first antisticking material is applied on the first free surface of the sheet 210 of a material containing alkaloids. Preferably, the thickness of said first coating layer 220 is comprised between about 5 micron and about 20 micron.

Further, the method of the invention includes a step 102 of applying a second coating layer 230 of a second antisticking material on the second free surface of the sheet 210 of a material containing alkaloids. Preferably, the thickness of said second coating layer 230 is comprised between about 5 micron and about 20 micron.

In this way, at the end of step 102, the multilayer coated sheet 200 of a material containing alkaloids comprising a layer 210 of a material containing alkaloids, a first coating layer 220 of a first antisticking material and a second coating layer 230 of a second antisticking material is obtained.

In Fig. 2, a lateral perspective view of the multilayer coated sheet 200 realized according to the method of the invention is shown. In Fig. 3, a lateral schematic view of an apparatus 300 for carrying out the method of the invention to produce the multilayer coated sheet 200 is shown, starting from the sheet 200 including a material containing alkaloids described above. Sheet 210 defines a free surface 305 and a second surface 306. Preferably, but not necessarily, the apparatus puts in operation the method of the invention described with reference to figure 1.

In Fig. 3, the apparatus 300 includes a conveyor belt 302 and an applying device 304. Conveyor belt 302 moves the sheet 210 of a material containing alkaloids along a transport direction (indicated by arrow 303) towards applying device 304.

Applying device 304 includes two coating devices 307 and 308. Coating devices 307 applies to first free surface 305 a coating layer 220 having a thickness of about 7 micron of a first antisticking material .

Coating device 308 applies to second free surface 306 a coating layer 230 having a thickness of about 7 micron of a second antisticking material. The antisticking materials applied by coating devices 307 and 308 are different each other, or they may be the same.

Downstream of coating devices 307 and 308, the multilayer coated sheet 200 comprising the layer (sheet) 210 of a material containing alkaloids, the first coating layer 220 of a first antisticking material and the second coating layer 230 of a second antisticking material is obtained, which is directed by roller 310 to further downstream processing steps.