Method for preparation of sheet including homogenized material containing alkaloids, and aerosol-forming article comprising component prepared from that method

Abstract

To provide a method for preparation of a sheet including a homogenized material containing alkaloids.SOLUTION: The method comprises: forming a mixture comprising particles of a material containing alkaloids and a starch component, and a quantity of a first additive comprising a component selected from the group consisting of water, an aerosol-former, and a binder, where the quantity of the first additive is between about 0.1 wt.% and about 50 wt.% based on the total weight of the mixture; applying to the mixture a mechanical energy of at least about 20 watt-hour per kilogram of the mixture; combining the mixture with a quantity of a second additive comprising a component selected from the group consisting of water, an aerosol-former, and a binder so as to form slurry; and forming a sheet from the slurry.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a sheet comprising homogenized alkaloid-containing material, such as homogenized tobacco material, and to an aerosol-forming article comprising a component prepared from the method. [Background technology]

[0002] Today, in addition to tobacco leaf, homogenized tobacco materials are also used in the manufacture of tobacco products. These homogenized tobacco materials are typically produced from parts of the tobacco plant that are less suitable for the production of cut filler (e.g., tobacco stems or tobacco dust). Tobacco dust is typically produced as a by-product during the handling of tobacco leaf during manufacturing.

[0003] The starting material for the production of homogenized tobacco material for aerosol-generating articles may therefore also be tobacco leaves that are largely identical in size and physical characteristics to the tobacco for blending cut filler.

[0004] Possible forms of homogenized tobacco material include reconstituted tobacco sheets and cast leaves. The process of forming homogenized tobacco material sheets generally involves mixing ground tobacco with a binder to form a slurry. The slurry is then used to create a tobacco web or sheet, for example by casting the viscous slurry onto a moving metal belt to produce so-called cast leaves. Alternatively, a lower viscosity, higher moisture content slurry can be used in a papermaking-like process to create reconstituted tobacco.

[0005] The sheet or web of homogenized tobacco material is typically ejected from a moving metal belt and wound onto a bobbin, which must be unwound for further processing and inclusion as an aerosol-forming substrate in an aerosol-forming article.

[0006] It would be desirable to improve or modify the process for forming sheets containing homogenized tobacco material in terms of its productivity.

[0007] In practice, sheets comprising homogenized tobacco material can be difficult to handle and store due to their consistency, sensitivity to heat, stickiness, or low tensile strength, and can easily break if too much force is used to handle the sheet. For example, once a sheet of homogenized tobacco material is coiled onto a bobbin, it can be difficult to remove or unwind from the moving metal belt on which it is positioned.

[0008] Furthermore, bobbins containing sheets of homogenized tobacco material can also be difficult to transport. Furthermore, it is preferable that the bobbins be used within a very short time frame, as otherwise the windings of the homogenized tobacco material sheet may bind together and impair unwinding. As a result, building a safety stock of such bobbins can also be a difficult task.

[0009] Therefore, there is a need for a method for producing sheets of alkaloid-containing material that are easily removed from the moving belt on which they are conveyed. There is a need for a method for producing sheets of alkaloid-containing material that is easy to unwind from a bobbin, thus allowing for a continuous, constant, and regular supply of material to downstream equipment, thereby increasing the overall production rate and improving production on the rest of the production line. Summary of the Invention

[0010] The present invention may satisfy at least one of the above needs.

[0011] In one aspect, the present invention relates to a method for preparing a sheet comprising homogenized alkaloid-containing material, the method comprising: forming a mixture comprising particles of the alkaloid-containing material and starch and a quantity of a first additive comprising a component selected from the group consisting of water, an aerosol former, and a binder, wherein the amount of the first additive is from about 0.1 weight percent to about 50 weight percent of the total weight of the mixture; applying to the mixture at least about 20 watt-hours of mechanical energy per kilogram of the mixture; combining the mixture with a quantity of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry; and forming a sheet from the slurry.

[0012] In another aspect, the present invention relates to a method for preparing a sheet comprising homogenized alkaloid-containing material, the method comprising: forming a mixture comprising particles of alkaloid-containing material and starch and an amount of water ranging from about 0.1 weight percent to about 50 weight percent of the total weight of the mixture; applying to the mixture at least about 20 watt-hours of mechanical energy per kilogram of the mixture; combining the mixture with an amount of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry; and forming a sheet from the slurry.

[0013] In another aspect, the present invention relates to a method for preparing a sheet comprising homogenized alkaloid-containing material, the method comprising: forming a mixture comprising particles of alkaloid-containing material and starch and a first amount of water ranging from about 0.1 weight percent to about 50 weight percent of the total weight of the mixture; applying to the mixture at least about 20 watt-hours of mechanical energy per kilogram of the mixture; combining the mixture with a second amount of water ranging from about 55 weight percent to about 90 weight percent of the total weight of the slurry to form a slurry; and forming a sheet from the slurry.

[0014] In the method of the present invention, a mixture is formed of particles of alkaloid-containing material and starch with an amount of a first additive comprising a component selected from the group consisting of water, an aerosol former, and a binder, wherein the amount of the first additive is from about 0.1 weight percent to about 50 weight percent of the total weight of the mixture.

[0015] At least about 20 watt-hours of mechanical energy per kilogram of mixture is applied to the mixture. Without being bound by theory, under these conditions, the first additive interacts with and modifies the starch contained in the alkaloid-containing material, such that the resulting mixture, when combined with a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry, may provide a sheet exhibiting improved properties with respect to consistency, sensitivity to heat, viscosity, or tensile strength.

[0016] As used herein, the term "sheet" refers to a laminar element having a width and length substantially greater than its thickness. Preferably, the width of a sheet is greater than about 10 millimeters, more preferably greater than about 20 millimeters or about 30 millimeters. Even more preferably, the width of a sheet is between about 100 millimeters and about 300 millimeters.

[0017] An "alkaloid-containing material" is a material that contains one or more alkaloids. The alkaloids may include nicotine. Nicotine may be found, for example, in tobacco. The alkaloid-containing material is preferably tobacco.

[0018] Alkaloids are a group of naturally occurring compounds that contain primarily 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 called alkaloids. In addition to carbon, hydrogen, and nitrogen, alkaloids may also contain other elements such as oxygen, sulfur, and more rarely, chlorine, bromine, and phosphorus.

[0019] Alkaloids are produced by a wide 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, and tubocurarine are examples of alkaloids.

[0020] As used herein, "starch" is part of the alkaloid-containing material. Starch may also be added separately.

[0021] Starch is a polymeric carbohydrate consisting of many glucose units joined by glycosidic bonds. It is produced as an energy reserve by most green plants. It is the most common carbohydrate in the human diet and is found in plants such as potato, wheat, maize (corn), rice, and tobacco. Starch consists of two types of polymer molecules, linear and cyclic amylose, and branched amylopectin, and is found in plants in a semi-crystalline granular state. As used herein, the term "slurry" refers to a liquid-like, viscous, or pasty material, including emulsions of different liquid-like, viscous, or pasty materials, and may contain a certain amount of solid particles, provided the slurry still exhibits liquid-like, viscous, or pasty behavior.

[0022] As used herein, the term "homogenized tobacco material" refers to a material formed by agglomerating tobacco particles that contains the alkaloid nicotine. Thus, the alkaloid-containing material can be a homogenized tobacco material.

[0023] The most commonly used forms of homogenized tobacco material are reconstituted tobacco sheets and cast leaves. The process of forming homogenized tobacco material sheets generally involves mixing tobacco dust with a binder to form a slurry. The slurry is then used to create tobacco sheets. For example, so-called cast leaves are produced by casting a viscous slurry onto a moving metal belt. Alternatively, a less viscous, higher moisture content slurry can be used to create reconstituted tobacco in a process similar to papermaking.

[0024] Tobacco sheet materials, which can be referred to as reconstituted sheet materials, can be formed using particulate tobacco (e.g., reconstituted tobacco) or a blend of tobacco particulates, a humectant, and an aqueous solvent to form a tobacco composition. This tobacco composition is then cast, extruded, rolled, or pressed to form a sheet material from the tobacco composition. Tobacco sheets can be formed using a wet process, in which tobacco fines are used to create a paper-like material, or a cast leaf process, in which tobacco fines are mixed with a binder material and cast onto a moving belt to form a sheet.

[0025] The homogenized tobacco material sheet may then be wound onto a bobbin and unwound for further processing, for example to become part of an aerosol-forming article, which may then become included in the aerosol-forming substrate of the aerosol-forming article. In "heat-and-burn" aerosol-generating articles, the aerosol-forming substrate is heated to a relatively low temperature to form an aerosol but prevent combustion of the tobacco material. Furthermore, the tobacco present in the homogenized tobacco sheet is typically the only tobacco or comprises the majority of the tobacco present in the homogenized tobacco material of such "heat-and-burn" aerosol-generating articles. This means that the aerosol composition generated by such "heat-and-burn" aerosol-generating articles is based substantially only on the homogenized tobacco material.

[0026] As used herein, the term "aerosol-forming material" refers to a material that has the ability to release volatile compounds upon heating to produce an aerosol. Tobacco can be classified as a homogenized tobacco sheet that contains an aerosol-forming material, particularly an aerosol former, along with other compounds. The aerosol-forming substrate can include or consist of an aerosol-forming material.

[0027] The properties of the homogenized tobacco material can affect the process for forming a sheet comprising the latter.

[0028] In fact, homogenized tobacco materials are generally "sticky," i.e., they adhere to adjacent objects, while at the same time having relatively low tensile strength and being rather brittle. Without being bound by theory, it is believed that these properties are due to the presence of binders and aerosol formers, such as guar and glycerin, in the homogenized tobacco material.

[0029] According to the method of the present invention, a sheet of alkaloid-containing material is produced.

[0030] A mixture is formed of particles of alkaloid-containing material and starch with an amount of a first additive comprising a component selected from the group consisting of water, an aerosol former, and a binder.

[0031] In this mixture, the amount of the first additive is about 0.1 weight percent to about 50 weight percent of the total weight of the mixture. The weight of the first additive represents 0.1 to 50 percent of the total weight of the mixture.

[0032] The weight ratio of the amount of the first additive in the mixture to the amount of starch in the alkaloid-containing material (i.e., the ratio of the weight of the first additive to the weight of the starch in the mixture) is preferably about 2 to about 80.

[0033] The amount of the first additive is preferably from about 5 weight percent to about 40 weight percent, and more preferably from about 10 weight percent to 30 weight percent, of the total weight of the mixture.

[0034] The mixture may include multiple first additives from the group described above. The particles and the first additives are preferably mixed by any known tool.

[0035] The first additive is preferably water, and the amount of water in the mixture is preferably about 5 weight percent to about 30 weight percent, more preferably about 10 weight percent to about 20 weight percent, and even more preferably about 10 weight percent to about 18 weight percent, based on the total weight of the mixture.

[0036] The mixture is then subjected to at least about 20 watt-hours of mechanical energy per kilogram of mixture.

[0037] The energy is applied by any known means, such as stirring, mixing, or other methods.

[0038] Under these conditions, the first additive interacts with and potentially modifies the starch contained in the alkaloid-containing material. Without wishing to be bound by any particular theory, the first additive may interact with the amylose and amylopectin polymers of the starch, modifying its crystalline and granular structure.

[0039] In this way, the starch modifies the properties of the resulting mixture, which is then combined with a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry. A sheet is then formed from the slurry, and the sheet may exhibit consistency, heat sensitivity, viscosity, or tensile strength properties optimal for use as a component of an aerosol-generating article. In particular, the sheet may have improved tensile strength, good heat resistance, or low viscosity or good consistency compared to a sheet formed from the same slurry but in which the starch component of the alkaloid-containing material does not interact with a specific amount of the first additive under specific conditions of applied mechanical energy prior to sheet formation.

[0040] The second additive is preferably added after mechanical energy has been applied to the mixture.

[0041] Forming the slurry preferably includes combining the mixture with water in an amount of about 55 weight percent to about 90 weight percent of the total weight of the slurry. The water can be the second additive or may be added along with additional second additives.

[0042] Preferably, the step of forming a slurry includes mixing a second additive with the mixture.

[0043] Furthermore, the sheet may exhibit better surface attributes, such as a smoother surface with fewer defects, compared to a sheet formed from the same slurry, but in which the alkaloid-containing material does not interact with the specific amount of the first additive under specific conditions of applied mechanical energy prior to forming the sheet.

[0044] Furthermore, the same slurry may exhibit optimal properties related to its viscosity and density, which may remain stable over time.

[0045] Preferably, the particles of the alkaloid-containing material have an average size of about 0.02 millimeters to about 0.3 millimeters, and more preferably, the average size is about 0.05 millimeters to about 0.2 millimeters.

[0046] An average size of about 0.02 millimeters to about 0.3 millimeters represents a size at which tobacco cells can be at least partially disrupted, and the use of alkaloid-containing material having such an average size advantageously results in a smooth and uniform slurry for downstream processing of the alkaloid-containing material.

[0047] Preferably, the first additive comprises water.

[0048] The first additive preferably comprises a binder.

[0049] The binder used as the first additive can be any of the gums or pectins described herein below. For descriptive reviews of gums that can be used as binders, see Gums and Stabilizers for the Food Industry, IRL Press (GO 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).

[0050] While any binder may be employed, preferred binders are natural pectins (such as fruit pectin, citrus pectin, or tobacco pectin), guar gum (such as hydroxyethyl guar and hydroxypropyl guar), locust bean gum (such as hydroxyethyl and hydroxypropyl locust bean gum), alginates, starches (such as modified or derivatized starches), celluloses (such as methylcellulose, ethylcellulose, ethylhydroxymethylcellulose, and carboxymethylcellulose), tamarind gum, dextran, puralon, konjac flour, xanthan gum, and the like. A particularly preferred binder for use in the first additive is guar.

[0051] Preferably, the first additive comprises an aerosol former.

[0052] Aerosol formers suitable as the first additive are known in the art and include, but are not limited to, monohydric alcohols (such as 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).

[0053] Examples of preferred aerosol formers are glycerin and propylene glycol.

[0054] The step of forming the mixture preferably includes adding reducing sugar in an amount of about 2 percent to about 30 percent by weight based on the dry weight of the mixture, more preferably about 5 percent to about 25 percent by weight based on the dry weight of the mixture, more preferably about 10 percent to about 15 percent by weight based on the dry weight of the mixture, and even more preferably about 11 percent to about 14 percent by weight based on the dry weight of the mixture.

[0055] The reducing sugars modify the alkaloid-containing material when mechanical energy is applied to the mixture, so that the resulting material may have different properties relative to the composition of the alkaloid-containing material compared to the alkaloid-containing material without the added reducing sugar. These differences affect the final properties of the sheet.

[0056] Reactions between reducing sugars and alkaloid-containing materials, particularly when the latter contain ammonia- and ammonium-containing compounds, can occur, modifying the composition of the alkaloid-containing material so that the resulting material has a lower amount of ammonia- or ammonium-containing compounds compared to alkaloid-containing materials without added reducing sugars, and the aerosol generated from the material may exhibit desirable or different characteristics, for example, flavor.

[0057] This amount of reducing sugar has proven to be optimal to obtain the desired properties in the final product, for example, a desired level of ammonia can be obtained.

[0058] Preferably, the reducing sugar is selected from glucose, fructose, xylose, ribose, galactose, and mixtures thereof. More preferably, the reducing sugar is glucose, fructose, and mixtures thereof.

[0059] The reducing sugar is preferably mixed with the alkaloid-containing material in powder, liquid or slurry form.

[0060] The alkaloid-containing material can be in any desired form before being mixed with the reducing sugar.

[0061] The amount of the first additive is preferably from about 10 percent to about 70 percent by weight based on the dry weight of the starch component of the alkaloid-containing material, more preferably from about 20 percent to about 60 percent by weight based on the dry weight of the starch component of the alkaloid-containing material, and even more preferably from about 30 percent to about 50 percent by weight based on the dry weight of the starch component of the alkaloid-containing material.

[0062] Preferably, at least about 50 watt-hours of mechanical energy per kilogram of mixture is applied to the mixture, more preferably at least about 100 watt-hours of mechanical energy per kilogram of mixture, more preferably at least about 150 watt-hours of mechanical energy per kilogram of mixture, more preferably from about 150 watt-hours to about 350 watt-hours of mechanical energy per kilogram of mixture, more preferably from about 200 watt-hours to about 300 watt-hours of mechanical energy per kilogram of mixture, and even more preferably from about 225 watt-hours to about 275 watt-hours of mechanical energy per kilogram of mixture.

[0063] The mechanical energy applied is preferably less than about 350 watt-hours per kilogram of mixture to avoid or minimize nicotine loss.

[0064] Preferably, the step of applying mechanical energy to the mixture comprises extruding the mixture.

[0065] Extrusion is a process used to create an object by forcing a material, in this case the mixture, through a die of a desired cross-section, where the mixture encounters compressive and shear stresses, thus forcing the mixture from the input to the output of the extruder while essentially absorbing energy.

[0066] Extrusion is a preferred method of applying mechanical energy to the mixture and may contribute to improved interaction between the first additive and the starch component of the alkaloid-containing material.

[0067] The step of applying mechanical energy is preferably carried out at a temperature of about 190° C. or less, more preferably at a temperature of about 30° C. to about 190° C. The maximum temperature reached during the step of applying energy is more preferably about 140° C. to about 190° C., even more preferably about 175° C. to about 185° C.

[0068] The extrusion temperature can affect the interaction between the first additive and the starch contained in the alkaloid-containing material, and the extrusion temperature in the extruder has been proven to be optimal for obtaining an interaction between the first additive and the starch contained in the alkaloid-containing material.

[0069] Other processing conditions such as the extrusion time of the extrusion may also be relevant factors as they may affect the interaction between the first additive and the starch of the alkaloid-containing material.

[0070] The step of applying mechanical energy is preferably carried out for an application time of about 10 seconds to about 80 seconds, more preferably about 10 seconds to about 60 seconds, even more preferably about 15 seconds to about 50 seconds, even more preferably about 20 seconds to about 30 seconds, and even more preferably about 22 seconds to about 27 seconds.

[0071] In the method of the present invention, the second additive may be the same as or different from the first additive.

[0072] Preferably, the second additive comprises water.

[0073] The second additive preferably comprises a binder. The binder used in the second additive may preferably be any of the gums or pectins described above with respect to the first additive. A particularly preferred binder for use in the second additive is guar.

[0074] The second additive preferably comprises an aerosol former. The aerosol former used in the second additive may be any of the aerosol formers described above with respect to the first additive. Examples of preferred aerosol formers in the second additive are glycerin and propylene glycol.

[0075] Preferably, the amount of the second additive is from about 200 percent to about 550 percent by weight based on the dry weight of the slurry, and more preferably from about 200 percent to about 500 percent by weight based on the dry weight of the slurry.

[0076] Preferably, the slurry comprises from about 45 percent to about 93 percent particles of the alkaloid-containing material on a dry weight basis, and more preferably, the slurry comprises from about 65 percent to about 83 percent particles of the alkaloid-containing material on a dry weight basis.

[0077] Preferably, the slurry contains from about 1 percent to about 10 percent binder on a dry weight basis, and more preferably, the slurry contains from about 4 percent to about 8 percent binder on a dry weight basis.

[0078] Preferably, the slurry contains from about 5 percent to about 30 percent aerosol former on a dry weight basis, and more preferably, the slurry contains from about 15 percent to about 25 percent aerosol former on a dry weight basis.

[0079] The slurry preferably contains from about 150 percent to about 500 percent water on a dry weight basis.

[0080] Prior to the sheet-forming step, the slurry preferably has a moisture content of about 10 percent to about 90 percent by weight, more preferably about 20 percent to about 80 percent by weight, even more preferably about 40 percent to about 80 percent by weight, and even more preferably about 60 percent to about 80 percent by weight.

[0081] In the method of the present invention, the step of forming a slurry preferably comprises homogenizing the slurry.

[0082] In the method of the present invention, the step of homogenizing the slurry is preferably carried out at a temperature of about 20°C to about 60°C, more preferably about 25°C to about 55°C.

[0083] Preferably, the method of the present invention comprises adding cellulose fibres to the alkaloid-containing material.

[0084] Cellulose fibers may be introduced into the slurry. The introduction of cellulose fibers into the slurry typically increases the tensile strength of the alkaloid-containing material and acts as a strengthening agent. Thus, adding cellulose fibers may increase the resilience of the alkaloid-containing material.

[0085] Cellulosic fibers for addition to alkaloid-containing materials, such as homogenized tobacco materials, are known in the art and include, but are not limited to, softwood fibers, hardwood fibers, jute fibers, flax fibers, tobacco fibers, and combinations thereof. In addition to pulping, the cellulosic fibers may be subjected to suitable treatments, such as refining, mechanical pulping, chemical pulping, bleaching, sulfate pulping, and combinations thereof.

[0086] The cellulose fibers may include tobacco stem material, petioles, or other tobacco plant materials. Preferably, the cellulose fibers, such as wood fibers, have a low lignin content. Alternatively, fibers such as plant fibers may be used in addition to or as a substitute for the above fibers, including hemp and bamboo.

[0087] The length of the cellulose fibers is advantageously between about 0.2 millimeters and about 4 millimeters. Preferably, the average length by weight of the cellulose fibers is between about 1 millimeter and about 3 millimeters.

[0088] Furthermore, the amount of cellulose fiber added to the alkaloid-containing material, in addition to the cellulose fiber already present in the alkaloid-containing material, is preferably from about 1 percent to about 7 percent, on a dry weight basis, of the total weight of the slurry.

[0089] Preferably, the method of the present invention includes the step of adding further alkaloid-containing material to the slurry.

[0090] Preferably, the step of forming a sheet from the slurry comprises casting the slurry into a sheet.

[0091] Preferably, the method of the present invention includes the step of drying the sheet comprising the homogenized alkaloid-containing material.

[0092] Preferably, the sheet containing the homogenized alkaloid-containing material has a moisture content of about 7 percent to about 15 percent by weight after drying.

[0093] Preferably, the sheet containing the homogenized alkaloid-containing material contains from about 45 percent to about 93 percent alkaloid-containing material on a dry weight basis.

[0094] Preferably, the alkaloid-containing material comprises homogenized tobacco material, in which case the alkaloids contained in the material may include nicotine.

[0095] According to a second aspect of the invention, the invention relates to an aerosol-forming article comprising a component prepared from the method according to the first aspect of the invention.

[0096] The advantages of the second aspect have already been outlined with reference to the first aspect and will not be repeated here.

[0097] The aerosol-forming article according to the present invention may be in the form of a filter cigarette or other smoking article in which tobacco material is combusted to form smoke. The present invention further encompasses articles that heat, rather than combust, tobacco material to form an aerosol, and articles that produce a nicotine-containing aerosol from tobacco material without the use of combustion or heating.

[0098] The aerosol-forming article according to the present invention may be a complete assembled aerosol-forming article, or may be a component of an aerosol-forming article that is combined with one or more other components to provide an assembled article for generating aerosol, such as, for example, a consumable part of a heated smoking device.

[0099] The aerosol-forming article may be an article that generates an aerosol that can be inhaled directly through the user's mouth into the user's lungs. The aerosol-forming article may resemble a conventional smoking article, such as a cigarette, and may contain tobacco. The aerosol-forming article may be disposable. Alternatively, the aerosol-forming article may be partially reusable and may comprise a refillable or replaceable aerosol-forming substrate.

[0100] The aerosol-forming article may also include a combustible cigarette. In a preferred embodiment, the aerosol-forming article may be substantially cylindrical. 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 an overall length of about 30 millimeters to about 100 millimeters. The aerosol-forming article may have an outer diameter of about 5 millimeters to about 12 millimeters.

[0101] In all aspects of the present invention, the alkaloid-containing material is preferably a homogenized tobacco material, in which case the alkaloids contained in the material may include nicotine.

[0102] Homogenized tobacco sheet comprises tobacco particles that have been ground from tobacco leaves (eg, tobacco stems and lamina).

[0103] The homogenized tobacco sheet may also include one or more small amounts of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the processing, handling, and transport of tobacco.

[0104] 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.

[0105] Specific embodiments of the present invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0106] [Figure 1] FIG. 1 shows a flow diagram of a method for producing a sheet containing homogenized tobacco material according to the present invention. [Figure 2] FIG. 2 shows a schematic side view of the extruder used to produce the extruded mixture. [Figure 3]Figure 3 shows the extruder thermal profile used in the extruder used to produce the extruded mixture. DETAILED DESCRIPTION OF THE INVENTION

[0107] Referring initially to FIG. 1, a method for producing sheets of homogenized alkaloid-containing material according to the present invention is depicted.

[0108] In a first step 100, a mixture of particles of alkaloid-containing material, a reducing sugar, and a first additive is formed. The alkaloid-containing material is tobacco material containing the alkaloid nicotine. Additionally, the tobacco contains starch. The reducing sugar is fructose. The first additive is water.

[0109] The mixture is (in weight percent of the total mixture): 64-82% tobacco powder, 8-18% added sugars; Preferably, it contains 10 to 18% added water.

[0110] The method includes a further step 101, for example, in which the mixture is subjected to energy in an extruder 200 (represented in Figure 2) comprising an inlet 201 and an outlet 202. In the extruder 200, the mixture moves along a direction of extrusion defined between the inlet 201 and the outlet 202, indicated by arrow 203 in Figure 2, and is subjected to a thermomechanical treatment.

[0111] Preferably, a mechanical energy of about 180 to about 435 watt-hours per kilogram of mixture is applied, more preferably, a mechanical energy of about 225 watt-hours per kilogram of mixture to about 275 watt-hours per kilogram of mixture.

[0112] During energy application, for example in an extruder, reducing sugars preferably undergo reaction with ammonia and ammonium-containing compounds of the tobacco material. Additionally, starch present in the tobacco also undergoes reaction with water.

[0113] In Figure 3 a schematic thermal profile along the direction of extrusion 203 of the extrusion process of the method of the invention is shown. Extrusion is one example of a possible energy application.

[0114] Step 101 of FIG. 1 includes substep 301 in which the mixture is fed into extruder 200 .

[0115] After substep 301, step 101 includes the further substep 302 of heating the mixture present inside extruder 200 to a first temperature of less than or equal to about 190°C. Preferably, the first temperature is from about 90°C to about 190°C, more preferably from about 140°C to about 190°C, and even more preferably from about 175°C to about 185°C. Heating is preferably carried out in a first section 204 of extruder 200. The residence time in the first section of the extruder is preferably from about 18 seconds to about 22 seconds.

[0116] After the substep 302 of heating the mixture to a first temperature, a further substep 303 is performed of cooling the mixture exiting the extruder 200 from the first temperature to a second temperature of 70°C or less. The second temperature is preferably between about 30°C and about 70°C, more preferably between about 35°C and about 50°C, and even more preferably between about 35°C and about 45°C. The cooling is preferably carried out in a second section 205 of the extruder 200, which is downstream in the direction of extrusion 203 of the first section 204 of the extruder 200. The residence time in the second section 205 of the extruder is preferably between about 18 seconds and about 22 seconds.

[0117] As shown in Figure 3, the extrusion step 101 can include maintaining the mixture at a first temperature, preferably in a first section 204 of an extruder 200, for a specified residence time prior to the step of cooling the mixture. Preferably, the residence time is from about 6 seconds to about 40 seconds. More preferably, the residence time is from about 7 seconds to about 11 seconds.

[0118] After sub-step 303 of cooling the mixture from the first temperature to a second temperature, a further step 304 is performed of discharging the mixture from the extruder 200 at the second temperature. In this manner, the tobacco mixture has a lower amount of ammonia or ammonium-containing compounds compared to the tobacco material prior to the extrusion process. Additionally, the starch may react with water.

[0119] The extruded mixture contained the same tobacco powder but the slurry was (by weight percent): 5-8% water, It is preferable to have these characteristics, that is, to contain 2-6% sugars (which have been reacted with ammonia).

[0120] After the extrusion step 101, the extruded mixture is used in the subsequent slurry preparation step 102.

[0121] Prior to or during the slurry preparation step 102, the method of the present invention comprises two further steps: a pulp preparation step 103 in which cellulose fibers 5 and water 6 are pulped to homogeneously disperse and refine the fibers in the water, and a suspension preparation step 104 in which an aerosol former 7 and a binder 8 are premixed. Preferably, the aerosol former 7 comprises glycerol and the binder 8 comprises guar. Advantageously, the suspension preparation step 104 comprises premixing the guar and glycerol without introducing water.

[0122] Preferably, the slurry preparation step 102 includes transferring a premixed solution of aerosol former and binder to a slurry mixing tank and transferring pulp to the slurry mixing tank. Additionally, the slurry preparation step includes dosing extruded tobacco powder from the extruder into the slurry mixing tank containing the pulp and dosing a suspension of guar and glycerol. Additional tobacco powder may be added. More preferably, this step also includes processing the slurry using a high shear mixer to ensure uniformity and homogeneity of the slurry.

[0123] The slurry preparation step 102 also preferably includes the step of adding water, where water is added to the slurry to obtain the desired viscosity and water content.

[0124] The slurry preferably has the following composition:

[0125] The mixture exiting the extruder is mixed with cellulose fiber. The resulting mixture is mixed with the (premixed guar gum glycerin) and water to form the following (in weight percent): - 15-30% tobacco mixture from the extrusion process; - 65-75% water, - 0.5-1.5% added cellulose fiber, - 0.1-1% guar gum, - Obtain a slurry of 2-7% glycerin.

[0126] The slurry formed by step 102 is preferably cast in a casting step 105 to form a sheet comprising homogenized tobacco material. This casting step 105 preferably includes transporting the slurry to a casting station and casting the slurry onto a substrate into a sheet of uniform, consistent film thickness. During casting, the thickness, moisture content, and density of the cast sheet are preferably controlled immediately after casting, and more preferably continuously monitored and feedback controlled throughout the process using a slurry measurement device.

[0127] The homogenized cast sheet is then dried in a drying step 106, which involves uniformly and gently drying the cast sheet, for example, in an endless stainless steel belt dryer. The endless stainless steel belt dryer may have individual controllable zones. The drying step preferably includes monitoring the cast sheet temperature in each drying zone to ensure a gentle drying profile in each drying zone, and heating the support on which the homogenized cast web is formed. The drying profile is preferably a so-called TLC drying profile.

[0128] At the end of the web drying step 106, a monitoring step (not shown) is performed to determine the moisture content in the dried web and the number of defects present.

[0129] The homogenized tobacco-containing sheet dried to the targeted moisture content is then preferably wound in a winding step 107, for example, to form a single master bobbin. Due to the improved properties of the homogenized tobacco-containing sheet according to the present invention, the sheet is easily ejected or unwound from the master bobbin without significant breakage of the sheet, increasing the productivity of the overall process. This master bobbin can then be easily used to carry out the production of smaller bobbins by a process of slitting to form smaller bobbins. The smaller bobbins may then be used for the production of aerosol-generating articles (not shown).

Claims

1. 1. A method for preparing a sheet comprising homogenized alkaloid-containing material, said method comprising: forming a mixture comprising particles of alkaloid-containing material and starch and a quantity of a first additive comprising a component selected from the group consisting of water, an aerosol former, and a binder, wherein the amount of the first additive is from about 0.1 weight percent to about 50 weight percent of the total weight of the mixture; - applying to said mixture at least about 20 watt-hours of mechanical energy per kilogram of said mixture; - combining the mixture with an amount of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry; forming a sheet from said slurry.

2. 10. The method of claim 1, wherein the second additive is added after the mechanical energy is applied to the mixture.

3. combining the mixture with an amount of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry; The method of any of claims 1 or 2, comprising combining the mixture with water in an amount of about 55 weight percent to about 90 weight percent of the total weight of the slurry.

4. 4. The method of claim 1, wherein the particles of the alkaloid-containing material have an average size of from about 0.02 millimeters to about 0.3 millimeters.

5. 5. The method of any one of claims 1 to 4, wherein the step of forming a mixture comprises adding reducing sugars in an amount of from about 2 percent to about 30 percent by weight based on the dry weight of the mixture.

6. said step of applying mechanical energy to said mixture comprising: The method of any one of claims 1 to 5, comprising extruding the mixture.

7. 7. The method of any one of claims 1 to 6, wherein the step of applying to the mixture at least about 20 watt-hours of mechanical energy per kilogram of the mixture is carried out at a temperature of about 190°C or less.

8. 8. The method of any one of claims 1 to 7, wherein the step of applying to the mixture at least about 20 watt-hours of mechanical energy per kilogram of the mixture is carried out for an application time of from about 10 seconds to about 80 seconds.

9. 9. The method of any one of claims 1 to 8, wherein the step of combining the mixture with a quantity of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry comprises adding a second additive in an amount of from about 150 percent to about 600 percent by weight based on the dry weight of the slurry.

10. 10. The method of any one of claims 1 to 9, wherein said step of combining said mixture with a quantity of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry is such that said slurry comprises from about 45 percent to about 93 percent of said particles of said alkaloid-containing material on a dry weight basis.

11. 11. The method of any one of claims 1 to 10, wherein said step of combining said mixture with a quantity of a second additive comprising a component selected from the group consisting of water, an aerosol former, and a binder to form a slurry is such that said slurry comprises from about 1 percent to about 10 percent of said binder on a dry weight basis.

12. 12. The method of any one of claims 1 to 11, wherein the step of combining the mixture with a quantity of a second additive comprising components selected from the group consisting of water, an aerosol former, and a binder to form a slurry is such that the slurry comprises from about 5 percent to about 30 percent of the aerosol former on a dry weight basis.

13. 13. The method of any one of claims 1 to 12, wherein said step of combining said mixture with a quantity of a second additive comprising components selected from the group consisting of water, an aerosol former, and a binder to form a slurry is such that said slurry comprises from about 150 percent to about 500 percent water on a dry weight basis.

14. - A method according to any one of claims 1 to 13, comprising adding cellulose fibres to the alkaloid-containing material.

15. 15. The method according to any one of claims 1 to 14, wherein the alkaloid-containing material is a tobacco material.

16. 16. The method of any one of claims 1 to 15, comprising the step of drying the sheet comprising the homogenized alkaloid-containing material.

17. 17. An aerosol-forming article comprising a component prepared from the method of claims 1-16.

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