Method and apparatus for producing multiple sheets of alkaloid-containing material

Abstract

The present invention relates to a method for producing a plurality of sheets of alkaloid-containing material, the method comprising: (100) providing a slurry comprising an alkaloid-containing material and water into a tank; (101) providing a plurality of outlets to the tank; (102) dispensing the slurry from the outlets onto a movable support to form a plurality of parallel sheets of the alkaloid-containing material; and (103) moving the movable support while maintaining the parallel sheets of the alkaloid-containing material separated on the movable support. The present invention also relates to an apparatus (1) for producing a plurality of sheets of alkaloid-containing material.

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for producing multiple sheets of alkaloid-containing material, and in particular to a method and apparatus for producing multiple sheets of material for use in aerosol-generating articles such as cigarettes or alkaloid-containing products of the "heat-not-burn" type. [Background technology]

[0002] Today, in addition to tobacco leaves, 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). Typically, tobacco dust is produced as a by-product during the handling of tobacco leaves during production.

[0003] 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 a tobacco web, for example by casting the viscous slurry onto a moving metal belt to produce so-called cast leaves. Alternatively, a slurry with a low viscosity and high moisture content can be used to create reconstituted tobacco in a process similar to papermaking. Once the homogenized tobacco web is prepared, it may be cut in a manner similar to uncut intact tobacco leaves to produce tobacco cut filler suitable for cigarettes and other smoking articles. A process for making such homogenized tobacco is disclosed, for example, in European Patent No. EP0565360.

[0004] In such processes, the slurry is cast onto a substrate, such as a moving belt, and then heated to obtain a sheet of material that can be further processed to obtain a component of an aerosol-generating article. The moving belt with the cast sheet thereon travels inside a long "dryer" where the temperature is controlled to gradually heat and dry the sheet.

[0005] After drying of the relatively wide sheet, the sheet is divided into smaller sections and then wound onto "small" bobbins. Alternatively, a large "master bobbin" is created and the entire sheet is wound onto a "large" bobbin and then stored. When the sheet needs to be further processed, the master bobbin is cut into smaller bobbins that are easier to handle.

[0006] Each time these process steps are performed, there is always a risk of damaging the sheet or smaller sections thereof due to the inherent fragility of the sheet and its "stickiness". Summary of the Invention [Problem to be solved by the invention]

[0007] There is a need for methods and apparatus that simplify the above-mentioned processes, addressing the specific properties of the sheets of alkaloid-containing material in order to minimize damage to them during manufacture. [Means for solving the problem]

[0008] The present invention relates to a method for producing a plurality of sheets of an alkaloid-containing material, the method comprising the steps of providing a slurry comprising an alkaloid-containing material and water into a tank, providing a plurality of outlets to the tank, dispensing the slurry from the outlets onto a movable support to form a plurality of parallel sheets of the alkaloid-containing material, and maintaining the parallel sheets of the alkaloid-containing material separated on the movable support while moving the movable support.

[0009] According to the invention, several sheets are formed simultaneously from the slurry. The sheets are arranged parallel to each other on the same movable support. In this way, there is no need to join the sheets after their production, since "smaller" sheets are already produced without lengthening the production, and since several sheets are produced in parallel. Furthermore, the smaller dimensions of the sheets may also allow faster and more uniform drying.

[0010] The term "sheet" as used herein means a layered element having a width and length substantially greater than its thickness. The combined width of the parallel sheets is preferably greater than about 10 millimeters, more preferably greater than about 20 or 30 millimeters. Even more preferably, the width of the sheet of alkaloid-containing material is comprised between about 60 millimeters and about 2500 millimeters. The thickness of the sheet of alkaloid-containing material is preferably comprised between about 50 micrometers and about 300 micrometers, more preferably, the thickness of the sheet is comprised between about 100 micrometers and about 250 micrometers, and even more preferably, the thickness of the sheet is comprised between about 130 micrometers and 220 micrometers.

[0011] The continuous "sheet" is referred to herein as a "web."

[0012] The term "movable support" as used herein means any means comprising at least one longitudinally movable surface. The movable support may form a closed loop to provide uninterrupted transport in one direction. The movable support may comprise a conveyor belt. The movable support may be essentially flat and may exhibit a structured or unstructured surface. The movable support may have no openings in its surface or may comprise orifices, preferably of a size such that the slurry deposited thereon cannot penetrate. The movable support may comprise a sheet-like movable and bendable band. The band may be made of a metallic material, including but not limited to steel, copper, iron alloys, copper alloys. The band may be made of rubber. The band may be made of a heat-resistant material so that it can be heated to accelerate the drying process of the slurry.

[0013] The term "slurry" as used herein means a liquid-like, viscous, or pasty material that may include an emulsion of different liquid-like, viscous, or pasty materials and may contain a certain amount of solid-state particles (although a slurry still exhibits liquid-like, viscous, or pasty behavior).

[0014] 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.

[0015] Alkaloids are a group of naturally occurring compounds that contain mostly basic nitrogen atoms. The group also includes some related compounds with neutral properties, and even some related compounds with 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.

[0016] Alkaloids are produced by a wide variety of organisms, including bacteria, fungi, plants, and animals. Alkaloids can be purified from crude extracts of these organisms by acid-base extraction. Caffeine, nicotine, theobromine, atropine, and tubocurarine are examples of alkaloids.

[0017] Preferably, the alkaloid-containing material comprises homogenized tobacco material. Thus, in this case, the alkaloid is nicotine. As used herein, the term "homogenized tobacco material" refers to a material formed by agglomerating particulate tobacco that contains the alkaloid nicotine.

[0018] 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 a tobacco web. For example, the viscous slurry is cast onto a moving metal belt to produce so-called cast leaves. Alternatively, a slurry with a low viscosity and high moisture content can be used to create reconstituted tobacco in a process similar to papermaking.

[0019] Tobacco sheet materials, which may be referred to as reconstituted sheet materials, may be formed using particulate tobacco (e.g., reconstituted tobacco) or a blend of tobacco particulates, a wetting agent, and an aqueous solvent to form a tobacco composition. This tobacco composition may then be cast, extruded, rolled, or pressed to form a sheet material from the tobacco composition. Tobacco sheets may 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.

[0020] Homogenized tobacco sheets generally contain, in addition to tobacco, a binder. Additionally, homogenized tobacco sheets may contain aerosol formers, such as guar and glycerin.

[0021] The term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that may form an aerosol. Typically, the aerosol-forming substrate releases the volatile compounds upon heating. The aerosol-forming substrate may comprise an alkaloid-containing material that contains a volatile alkaloid flavour compound, which is released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may comprise a homogenised material.

[0022] A slurry is formed to form a sheet of material containing the alkaloid.

[0023] The slurry may contain a number of different components or ingredients. These components may affect the properties of the cast sheet of alkaloid-containing material. The first component is the alkaloid-containing material, for example in powder form. This material may be, for example, a tobacco powder blend, which preferably contains the majority of the tobacco present in the slurry. The tobacco powder blend is the source of the majority of the tobacco in the homogenized tobacco material and therefore imparts flavor to the final product, for example the aerosol produced by heating the homogenized tobacco material.

[0024] The powder of the alkaloid-containing material preferably has a size of about 0.03 millimeters to about 0.12 millimeters. The size of the particles or powder of the alkaloid-containing material refers to the Dv95 size. Each of the values ​​listed above indicates the Dv95 of the particle size. The "v" in Dv95 means that the volume distribution is taken into account. The use of the volume distribution introduces the concept of an equivalent sphere. An equivalent sphere is a sphere that is equivalent to the actual particle in the property we are measuring. It is therefore a sphere that will produce the same scattering intensity as the actual particle in light scattering methods. This is essentially a sphere with the same volume of particles. Furthermore, the "95" in Dv95 refers to the diameter at which 95% of the distribution has a smaller particle size and 5% has a larger particle size. The particle size is therefore that size by volume distribution at which 95 percent of the particles have a diameter smaller than the stated value (the diameter of the corresponding sphere having substantially the same volume of the particle). A particle size of 60 micrometers means that 95 percent of the particles have a diameter smaller than 60 micrometers, the diameter being the diameter of a sphere having a corresponding volume smaller than the particle.

[0025] The Dv95 size of particles is measured using a Horiba LA950 or LA960 particle size distribution analyzer. The HORIBA LA-960 particle size analyzer measures size distribution using laser diffraction. This technique uses first principles to calculate size using light scattered off the particle (edge ​​diffraction) and light transmitted through the particle (secondary scattering refraction). The LA-960 incorporates Mie scattering theory.

[0026] A binder may be added to the slurry to enhance the tensile properties of the homogenized sheet. An aerosol former may be added to the slurry to facilitate the formation of an aerosol. Additionally, water may be added to the slurry to reach a certain viscosity and moisture content that is optimal for casting a web of the alkaloid-containing material.

[0027] The amount of binder added to the slurry may comprise about 1 percent to about 5 percent by dry weight of the slurry. More preferably, the amount of binder comprises about 2 percent to about 4 percent. The binder used in the slurry may be any of the gums or pectins described herein. The binder may ensure that the powder of the alkaloid-containing material, such as tobacco, remains substantially dispersed throughout the homogenized tobacco web. While any binder may be employed, preferred binders are natural pectins (such as fruit pectins, citrus pectins, or tobacco pectins), guar gums (such as hydroxyethyl guar, hydroxypropyl guar, etc.), locust bean gums (such as hydroxyethyl locust bean gum, hydroxypropyl locust bean gum, etc.), alginates, starches (such as modified or derivatized starches), celluloses (such as methylcellulose, ethylcellulose, ethylhydroxymethylcellulose, carboxymethylcellulose, etc.), tamarind gum, dextran, pralon, konjac flour, xanthan gum, and the like. A particularly preferred binder for use in the present invention is guar.

[0028] Suitable aerosol formers for inclusion in the slurry for the alkaloid-containing material are well 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, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.).

[0029] Examples of preferred aerosol formers are glycerin and propylene glycol.

[0030] The slurry may have an aerosol former content of greater than about 5 percent on a dry weight basis. The slurry may have an aerosol former content of about 5 to about 30 percent on a dry weight basis. More preferably, the aerosol former comprises about 10 to about 25 percent of the dry weight of the slurry. More preferably, the aerosol former comprises about 15 to about 25 percent of the dry weight of the slurry.

[0031] To increase the tensile strength of the alkaloid material web, cellulose pulp containing cellulose fibers is preferably added to the slurry, which acts as a reinforcing agent.

[0032] The introduction of cellulose fibers into the slurry typically increases the tensile strength of the sheet of alkaloid-containing material and acts as a reinforcing agent. Thus, adding cellulose fibers may increase the elasticity of the sheet of alkaloid-containing material. Cellulosic fibers for inclusion in slurries for sheets of alkaloid-containing material are well 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 cellulose fibers may be subjected to suitable processes such as refining, mechanical pulping, chemical pulping, bleaching, sulfate pulping, and combinations thereof. The cellulose fibers may include tobacco stem material, petioles, or other tobacco plant materials. Cellulosic fibers such as wood fibers preferably include a low lignin content. Alternatively, fibers such as plant fibers may be used in conjunction with or as a replacement for the above fibers, including hemp and bamboo. The length of the cellulose fibers is advantageously about 0.2 millimeters to about 4 millimeters. The average length by weight of the cellulose fibers is preferably about 1 millimeter to about 3 millimeters. Further, the amount of cellulose fibers preferably comprises from about 1 percent to about 7 percent, on a dry weight basis, of the total weight of the slurry (or homogenized tobacco sheet).

[0033] The average length of fibres refers to their actual length (whether they are curled or kinked) as measured by the MORFI COMPACT commercialized by Techpap SAS. The average length is the mathematical average of the fibre lengths measured by the MORFI COMPACT for measurements of N fibres (where N>5). The MORFI COMPACT is a fibre analyzer that measures the fibre length according to the fibre structure and therefore measures the actual generated length of the fibre. A measured object is considered a fibre if its length is comprised between 200 micrometres and 10000 micrometres and its width is comprised between 5 micrometres and 75 micrometres. The fibre length is measured when deionised water is added to the fibre and the Morfi software is used.

[0034] The binder and the cellulose fibers are preferably contained in a weight ratio comprised between about 1:7 and about 5:1, and more preferably in a weight ratio comprised between about 1:1 and about 3:1.

[0035] The binder and the aerosol former are preferably present in a weight ratio of about 1:30 to about 1:1. More preferably, the binder and the aerosol former are present in a weight ratio of about 1:20 to about 1:4.

[0036] The alkaloid-containing material is preferably tobacco. The binder and tobacco particles are preferably present in a weight ratio of about 1:100 to about 1:10. More preferably, the binder and tobacco particles are present in a weight ratio of about 1:50 to about 1:15, and even more preferably, about 1:30 to 1:20.

[0037] The aerosol formers and tobacco particles are preferably included in a weight ratio of about 1:20 to about 1:1. The aerosol formers and tobacco particles are more preferably included in a weight ratio of about 1:6 to about 1:2.

[0038] The aerosol-forming material and the cellulose fibers are preferably included in a weight ratio of about 1:1 to about 30:1, and more preferably in a weight ratio of about 5:1 to about 15:1.

[0039] The cellulose fibers and tobacco particles are preferably contained in a weight ratio of about 1:100 to about 1:10, and more preferably in a weight ratio of about 1:50 to about 1:20.

[0040] The slurry formed of the alkaloid-containing material, water, and preferably the material containing some or all of the above-mentioned ingredients may be contained in a tank, for example. The slurry may reach the tank from a different location. Thus, the tank may not be the location where the slurry is formed. For example, the slurry may be created in a silo and transferred from there to the tank via appropriate piping.

[0041] The slurry inside the tank is preferably kept at about ambient temperature, ie, between about 15 degrees Celsius and about 30 degrees Celsius.

[0042] From the tank, the slurry is transferred to a movable support to form a plurality of sheets, the sheets being preferably formed on a surface of the movable support, such as a conveyor belt, the direction along which the movable support moves defining a conveying direction.

[0043] The tank is preferably located above a moveable support and the surface of the moveable support on which the sheet is formed preferably defines a substantially horizontal surface.

[0044] The slurry is continuously fed to the tank, while the slurry is preferably fed onto a moveable support to form a plurality of continuous sheets of the alkaloid-containing material. Hence, the silo and the tank are preferably fluidly connected to allow the slurry to flow from one to the other.

[0045] The level of the slurry is preferably checked inside the tank, for example by a suitable sensor. The slurry is preferably introduced into the tank by a pump. More preferably, there is a feedback control loop, where a signal from the sensor regarding the level of the slurry can modify the pump output.

[0046] In this manner, a predefined amount of slurry is preferably maintained in the tank.

[0047] The tank is preferably box-shaped. Preferably, the tank comprises a wall. More preferably, the wall then comprises a side wall. The side wall may comprise a first pair and a second pair of opposing walls, referred to as a first side wall, a second side wall, a third side wall and a fourth side wall. The side walls are advantageously substantially vertical or inclined with respect to a vertical plane. The first side wall and the second side wall, as well as the third side wall and the fourth side wall, face one towards the other. The tank wall also preferably comprises a bottom wall.

[0048] The tank includes a number of outlets. The outlets are formed on a wall of the tank, for example the bottom wall. The outlets formed in the tank can be arranged in any configuration. The outlets are preferably distributed along a line. The outlets can be located at the end of a pipe extending from the tank. In this case, the tank may have one opening (for example in the bottom wall), from which a main pipe extends. The main pipe then branches into multiple pipes, each terminating in an outlet. Alternatively, multiple openings are formed in the tank (for example in the bottom wall), from which multiple pipes extend, each starting from an opening and terminating in an outlet. Thus, in this case, the outlet may be located at the end of a pipe that supplies the slurry to the movable support.

[0049] The slurry is dispensed from the outlet onto a movable support.

[0050] The slurry may be applied directly onto the movable support, or one or more substrate sheets may be placed between the movable support and the tank such that the slurry is applied to the substrate sheets. The substrate sheets may be positioned on the movable support.

[0051] Preferably, the distance between the two nearest adjacent outlets remains constant among all outlets.

[0052] Considering the bottom wall of the tank as defining an (X,Y) plane (X being parallel to the conveying direction) and considering the side wall (at least across the component) as extending along a Z axis parallel to the (X,Y) plane, the outlets preferably form a line parallel to the Y axis, however the outlets may be arranged in multiple parallel lines.

[0053] The moving support is preferably moved along a longitudinal axis (conveying direction) to remove the slurry exiting the outlet. The dimension of the movable support perpendicular to the conveying direction is referred to as the width of the movable support. The support may comprise a movable belt, for example made of stainless steel. The support is preferably moved by a drum adapted to advance the movable support. The drum is further adapted to be in thermal contact with the movable support for the sheet of material containing the alkaloid.

[0054] The multiple outlets distribute the slurry at different locations onto the movable support or onto a substrate sheet placed on the movable support. Due to the fact that the movable support moves along the conveying direction, the distributed slurry forms different slurry sheets, one for each different outlet, extending along the conveying direction. The dimension of the sheet formed on the movable support in a direction perpendicular to the conveying direction is called the sheet width.

[0055] Preferably, each of the sheets has a width of about 10 millimeters to about 300 millimeters. All of the sheets simultaneously formed from the outlet preferably have substantially the same width.

[0056] Preferably, the sheets formed from the outlets are non-overlapping, i.e. each sheet has one surface in contact with the movable support or substrate sheet. The sheets are not placed on top of another sheet. Preferably, there is no contact between different sheets formed from different outlets.

[0057] The sheets are maintained separated from one another during movement of the movable support because otherwise the sheets would tend to bond together to form a single sheet due to the substantially liquid or pasty state of the slurry. Hence, the parallel sheets formed by the differently located outlets are maintained separated while the movable support transports them along the transport direction.

[0058] In this way, multiple sheets are formed simultaneously, each having a relatively "small" width suitable for further processing steps, e.g., to form an aerosol-generating article, and steps such as splitting the sheet into multiple smaller sheets along the conveying direction are avoided.

[0059] Preferably, on at least a section of the movable support, a substrate sheet is provided. Preferably, a number of substrate sheets equal to the number of outlets are provided. The slurry is then deposited above the substrate sheet, whereby the slurry and substrate sheet together form a plurality of sheets of alkaloid-containing material.

[0060] The substrate sheet is preferably a substrate sheet comprising fibers, which may be used to form a sheet of alkaloid-containing material having a relatively high tensile strength, which may be used with a slurry having a low fiber content to strengthen the resulting sheet of alkaloid-containing material.

[0061] The substrate sheet containing the fibers is typically a relatively "strong" sheet, the tensile strength of which is such that it can be transported between rollers without the need for any additional substrate on which it must be in contact. The tensile strength of the substrate sheet is typically about 0.1 Newtons / (millimeter) 2 ~1 Newton / (mm) 2 It is preferable that the composition comprises:

[0062] The substrate sheet may be made of different materials, natural or synthetic, including cellulose, hemp, kenaf, bamboo pulp, cotton, silk, wood, or combinations thereof. The choice of material is made according to the mechanical properties expected of the final sheet containing the alkaloid-containing material.

[0063] The fibers in the base sheet may be woven or non-woven. If not woven, the fibers may be oriented primarily in one direction. Also, the fibers may be oriented, for example, randomly. If woven, a variety of patterns can be used. The base sheet may comprise a mat of fibers. The fibers may be randomly arranged, flattened into a sheet, or woven into a fabric. The base sheet may include a binder to hold the fibers together. The binder may include methylcellulose.

[0064] The base sheet is preferably a braided sheet. A braided sheet is a sheet in which fibers are entangled. It is not necessary for all the fibers to be entangled, but some of them are. A braided sheet makes it possible to obtain a homogeneous and relatively high mechanical strength.

[0065] The fiber content in the base sheet is 50 grams / (meter) 2 It is preferable that the temperature is lower than 100°C.

[0066] The substrate sheet preferably comprises cellulose fibers. Cellulosic fibers forming the sheet are well known in the art and include, but are not limited to, softwood fibers, hardwood fibers, jute fibers, flax fibers, tobacco fibers, and combinations thereof. The cellulose fibers may be subjected to suitable processes such as refining, mechanical pulping, chemical pulping, bleaching, sulfate pulping, and combinations thereof, in addition to pulping. The cellulose fibers may comprise tobacco stem material, leaf stalks, or other tobacco plant materials. The cellulose fibers, such as wood fibers, preferably comprise a low lignin content. Alternatively, fibers such as plant fibers may be used in conjunction with or as a replacement for the above fibers, including hemp and bamboo.

[0067] The fiber-containing base sheet comprises fibers having an average fiber length of about 0.7 mm to about 50 mm. More preferably, the fiber of the fiber-containing base sheet comprises fibers having an average fiber length of about 1 mm to about 25 mm. More preferably, the fiber of the fiber-containing base sheet comprises fibers having an average fiber length of about 1 mm to about 10 mm. More preferably, the fiber of the fiber-containing base sheet comprises fibers having an average fiber length of about 1 mm to about 5 mm. Even more preferably, the fiber of the fiber-containing base sheet comprises fibers having an average fiber length of about 1.2 mm to about 1.8 mm.

[0068] The average length of fibres refers to their actual length (whether they are curled or kinked) as measured by the MORFI COMPACT commercialized by Techpap SAS. The average length is the mathematical average of the fibre lengths measured by the MORFI COMPACT for measurements of N fibres (where N>5). The MORFI COMPACT is a fibre analyzer that measures the fibre length according to the fibre structure and therefore measures the actual generated length of the fibre. A measured object is considered a fibre if its length is comprised between 200 micrometres and 10000 micrometres and its width is comprised between 5 micrometres and 75 micrometres. The fibre length is measured when deionised water is added to the fibre and the Morfi software is used.

[0069] The substrate sheet defines a first surface and a second surface, one opposite the other. The first surface or the second surface may be a substantially planar surface. The first surface or the second surface may be horizontal, i.e., parallel to a horizontal plane, or may be inclined.

[0070] The second surface is preferably in contact with the movable support, while the slurry is preferably deposited on the first surface.

[0071] The slurry that contacts the base sheet may be completely absorbed or adsorbed by the base sheet. The slurry may form a layer, referred to as the second layer, on the first surface of the base sheet. The slurry may be partially absorbed or adsorbed by the base sheet and may partially cover the first surface of the base sheet.

[0072] Preferably, the application of the slurry may form a second layer on the substrate sheet. In effect, a coating layer of the slurry is formed on the first surface of the substrate sheet.

[0073] The slurry may be applied by impregnating the substrate sheet with the slurry.

[0074] Depending on the composition of the base sheet, or the composition of the slurry, or the compositions of both the base sheet and the slurry, for example the amount of water or the amount of binder contained in the slurry, the slurry may be minimally, partially, or mostly absorbed or adsorbed by the base sheet. If the slurry is only minimally or partially absorbed by the base sheet, a second layer is formed on the surface of the base sheet where the slurry is applied, and a multi-layer sheet is formed.

[0075] When an adsorption process is performed in which the slurry is absorbed or adsorbed by the base sheet, the base sheet becomes impregnated with the slurry. The slurry may be completely absorbed by the base sheet. The slurry may also form a coating layer and impregnate the base sheet.

[0076] Sorption is a physical and chemical process by which one substance binds to another. Specific instances of sorption are absorption (a substance in one state is incorporated into another substance in a different state, and such a liquid slurry is absorbed by a solid substrate sheet), or adsorption (ions and molecules are physically attached or bound onto the surface of another phase).

[0077] The resulting sheet formed by the substrate sheet and the slurry applied to the first surface may have different compositions in a cross section taken perpendicular to the first surface of the substrate sheet. At the second surface, the lowest concentration of the slurry may be present. At the first surface, the highest concentration of the slurry may be present. Between the first and second surfaces, the combination of substrate sheet material and slurry may be present in different concentrations.

[0078] The method preferably includes the step of simultaneously drying parallel sheets of alkaloid-containing material. After casting, the sheets are preferably dried to reduce their moisture content and then "cured". A drying station (or "dryer" for short) can be used to dry the sheets. Drying all the sheets together speeds up the process. In addition, drying "smaller" sheets versus wider sheets can result in more uniform drying of the sheets themselves minimizing resulting defects.

[0079] In the drying station, the temperature of the sheet is preferably increased so that the moisture inside the sheet can be reduced. The moisture of the sheet at the casting step, i.e., the moisture of the slurry, is preferably about 60 percent to about 80 percent. The moisture of the sheet at the end of drying is preferably about 7 percent to about 15 percent of the total weight of the sheet of alkaloid-containing material. The moisture of the sheet of alkaloid-containing material at the end of drying is preferably about 8 percent to about 12 percent of the total weight of the sheet of alkaloid-containing material. The moisture of the slurry at the time of casting and at the end of the drying process is an important parameter to be controlled since it affects the homogeneity of the sheet and the manufacturability of the sheet of alkaloid-containing material in the subsequent manufacturing steps.

[0080] The ideal level of moisture in the slurry has been found to be about 60 percent to about 80 percent. Below this preferred range, the density of the slurry as cast is such that it frequently causes the appearance of defects in the formed sheet. Also, moisture levels outside this range may result in a reduction in the tensile strength of the sheet, which may complicate efficient handling of the sheet of alkaloid-containing material in subsequent processing steps. Thus, the excess moisture that needs to be removed from the sheet during the drying step is significant.

[0081] The removal of moisture is preferably carried out by exposure to a flow of heated fluid, which can for example be drying air, the drying air having a temperature higher than that of the cast sheet, although steam can also be used.

[0082] The step of feeding the slurry from the outlet onto the movable support preferably includes the step of spraying or discharging the slurry onto the movable support. To feed the slurry from the tank onto the movable support, the slurry can be sprayed or discharged onto the movable support, for example, by a suitable nozzle or gun. Thus, simple and effective sheet formation is achieved.

[0083] The method preferably includes adjusting the pressure or flow rate of the slurry dispensed from each of the plurality of outlets separately. The flow rate of at least one of the outlets is preferably adjusted separately from the other flow rates. More preferably, the method includes modifying the pressure of the slurry dispensed from each of the plurality of outlets based on the flow rate of the slurry dispensed from the same outlet. The amount and pressure of the slurry exiting each outlet is preferably monitored. This monitoring step may be part of a feedback loop, whereby the pressure at which the slurry is expelled or sprayed onto the movable support may vary depending on the amount of slurry per unit time forced onto the movable support. Thus, an optimal distribution of the slurry onto the movable support is obtained. In addition, the amount of slurry used to form each of the plurality of sheets is preferably the same.

[0084] The method preferably includes the step of stirring the slurry in the tank. The slurry generally reaches the tank already in a mixed state. In order to obtain a slurry with substantially identical properties at all outlets in the tank (which are located at different locations), stirring is also preferably performed inside the tank, for example by a mixing device such as a screw conveyor. In addition, the constant stirring or mixing avoids any part of the slurry drying out.

[0085] The method preferably includes the step of heating the slurry at one or more of the multiple outlets or within the tank. The "hot" slurry is a less viscous slurry and is therefore more easily distributed, particularly by spraying or discharging, onto a movable support. The temperature of the slurry at the outlet is preferably comprised between about 20 degrees Celsius and about 50 degrees Celsius.

[0086] The method preferably includes directing a stream of slurry provided from one or more of the multiple outlets relative to the movable support. It is preferably possible to adjust the direction in which the slurry from the tank reaches the movable support. The shape of the slurry stream can also preferably be altered. In this way, the slurry stream can be adjusted to obtain the desired sheet, achieving better precision in sheet formation.

[0087] The present invention also relates to an apparatus for producing a plurality of sheets of an alkaloid-containing material, the apparatus comprising a tank adapted to contain the slurry and having a plurality of outlets, a movable support adapted to move along a conveying direction, and a plurality of separators positioned parallel to the conveying direction and in contact with a surface of the movable support, the separators dividing the surface of the movable support into a number of sections, each of the plurality of outlets being located above a section.

[0088] The advantages of such an apparatus have already been described with respect to the present method and will not be repeated here. The slurry from the tank is transferred to the movable support via an outlet. In order to keep the slurry sheets separated from one another, the movable support on one of its surfaces (preferably the surface facing the tank) comprises a number of separators, whereby the slurry forming the various sheets is "confined" within the space defined by the separators, i.e. confined to limited portions of the surface of the movable support.

[0089] Each outlet passes through a section of the movable support formed by the separator, and preferably each of the multiple outlets passes through a different section, although configurations in which two or more outlets pass through the same section are also possible.

[0090] The apparatus preferably includes a spray or discharge gun at each of the plurality of outlets, for example positioned at the end of a pipe extending from each outlet, and used to spray or discharge the slurry onto that section of the movable belt.

[0091] The apparatus preferably includes a pressure regulator at each of the plurality of outlets.The apparatus preferably includes a flow meter at each of the plurality of outlets.Preferably there is control of the parameters of the flow of the slurry from the tank to the movable support.

[0092] The width of the sections perpendicular to the conveying direction is preferably comprised between about 10 mm and about 300 mm. Preferably, the width of each of the plurality of sheets is such that it is equal to or similar to the "standard" width of the small bobbins obtained by dividing the "master" sheet, so that the small sheets can immediately undergo further process steps, for example to obtain aerosol-generating articles.

[0093] The height of the section in a direction perpendicular to the conveying direction is preferably comprised between about 10 millimeters and about 100 millimeters. The thickness of each of the plurality of sheets is preferably comprised between about 5 millimeters and about 20 millimeters. The thickness of all of the plurality of sheets is preferably substantially the same. The height of the section (here height is intended to mean the dimension substantially perpendicular to the surface of the movable support on which the slurry is deposited) is wide enough to encompass the amount of slurry required to obtain such sheet thickness.

[0094] Preferably, the size or shape of each of the plurality of outlets is variable. The size and / or shape of the outlets can be varied to better control the flow of the slurry.

[0095] The invention will now be better explained with reference to the accompanying drawings. [Brief description of the drawings]

[0096] [Figure 1] FIG. 1 is a schematic diagram of an apparatus for the production of multiple sheets of alkaloid-containing material according to the present invention. [Diagram 2] FIG. 2 is a more detailed front view of the device of FIG. [Diagram 3] FIG. 3 is a more detailed schematic side view of a portion of the apparatus of FIG. [Figure 4] FIG. 4 is a side view of a detail of the device of FIG. [Diagram 5] FIG. 5 is a cross-sectional front view of a detail of FIG. [Figure 6] FIG. 6 is a flow chart of a method for producing multiple sheets of alkaloid-containing material in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0097] 1, an apparatus for producing a plurality of sheets of alkaloid-containing material, all generally designated 10, in accordance with the present invention is provided and designated by the reference numeral 1. In this embodiment, the plurality of sheets 10 are sheets of homogenized tobacco material.

[0098] The apparatus 1 for producing multiple sheets of homogenized tobacco material comprises a sheet former 2 and, preferably, also a drying apparatus 3 positioned downstream of the sheet former 2 in the direction of movement 11 (indicated by the arrow in FIG. 1 ) of the multiple sheets 10 of alkaloid-containing material.

[0099] Referring now to Figure 2, the sheet forming apparatus 2 comprises a tank 4 into which a slurry for forming a web of homogenized tobacco material is introduced, a pump 5 for introducing the slurry into the tank, a number of outlets, all indicated at 6, and a movable support 7 onto which the slurry is delivered from the outlet 6. The tank 4 may have any geometric shape and in the embodiment shown is substantially prismatic. Slurry from a buffer tank or silo (not shown in the drawings) is transferred into the tank by the pump 5. The pump 5 is preferably equipped with a flow control (not visible in the drawings) that controls the amount of slurry introduced into the tank 4. The pump 5 is advantageously designed to ensure that the transfer time of the slurry is kept to the minimum necessary. Furthermore, a sensor 40 is present in the tank 4 to measure the level of the slurry. There is preferably a feedback between the sensor 40 and the pump 5, whereby an optimum level of the slurry is substantially maintained in the tank 4 at all times.

[0100] The tank 4 includes a side wall 15 and further includes a bottom wall 16. A mixer 17 may be present inside the tank for agitating and / or mixing the slurry. The mixer may be, for example, a screw conveyor driven into operation by a motor 18.

[0101] The sheet forming apparatus 2 also comprises a movable support 7 onto which the slurry is fed to form a web 10 of homogenised tobacco material. The movable support 7 may for example comprise a continuous stainless steel belt 7 comprising a drum assembly. The drum assembly includes a main drum 8 (visible in Figures 3 to 5) which is located below the tank 4 and which moves the movable support 7. The tank 4 is preferably mounted above the main drum 8. The conveying direction of the movable support 7 corresponds to the direction of movement 11.

[0102] The width of the tank 4 (by width the direction perpendicular to the conveying direction 11 is meant) is preferably substantially the same as the width of the movable support 7 .

[0103] In the bottom wall 16 of the tank an opening 16a is formed and is connected to a main pipe 20. A main valve 21 regulates the flow of the slurry through the main pipe 20. Downstream of the main valve 21 in the direction of slurry flow, the main pipe 20 branches into a number of branch pipes, all indicated with 22. The number of branch pipes 22 is equal to the number of outlets 6, and in fact each branch pipe 22 terminates in an outlet 6 at its free end.

[0104] In an alternative embodiment (not shown), multiple openings are formed directly in the bottom wall 16 and multiple pipes are connected, with each pipe connecting to a different opening.

[0105] Each branch pipe is equipped with a valve 23 followed by a volumetric pump 24 (e.g. a lobe or gear pump), a pressure regulator 25 and a flow meter 26. Elements 23-26 are listed in the direction of slurry flow from the most upstream element (valve 23 located downstream of main valve 21) to the most downstream element (flow meter 26). Flow meter 26 and volumetric pump 24 are preferably part of a feedback system, whereby the value output by flow meter 26 regulates the volume of slurry delivered through pipe 22 by pump 24.

[0106] The series of elements is shown in FIG. 3, where a side view of the sheet forming apparatus 2 is taken.

[0107] Each branch pipe 22 terminates in a gun 27 at which there is an outlet 6. Each gun 27 includes a nozzle (not visible) representing the outlet, which may for example be a slit for injected slurry or a circle for sprayed slurry.

[0108] The gun 27 may be an ejector gun or a spray gun. In both systems (i.e. with an ejector gun or a spray gun) it may be possible to adjust the position and / or the inclination of the gun. Furthermore, compressed air may be used with an air pressure regulator to push the slurry out. In the case of an ejector gun, it is preferred that the outlet has an adjustable shape and size. In the case of an ejector gun, it is preferred that an adjustable spray shape (cone, spiral, etc.) is provided on the ejector gun.

[0109] The guns 27 preferably form a line, ie they are aligned along an axis, which line is preferably perpendicular to the conveying direction 11 .

[0110] Additionally, each branch pipe 22 may include an electric heating element and a temperature sensor (not shown in the drawings). Heating is used to prevent cooling of the slurry during transport.

[0111] As can be better seen in Fig. 4 and Fig. 5, the movable support 7 defines a surface 7a. The surface 7a is preferably planar. The movable support 7 includes a plurality of separators 30 positioned on the surface 7a of the movable support 7 in contact with the slurry. The separators 30 divide the surface 7a of the movable support into sections 31. The separators 30 preferably include walls, such as vertical walls, that are parallel to each other. The walls are parallel to the conveying direction 11 and are connected to the belt by threads, so that they move / loop together with the belt. The width 32 of each section is preferably the width of a standard "small bobbin" (e.g., preferably between about 10 millimeters and about 300 millimeters) used for further processing of the sheet 10. The widths 32 of all sections are preferably the same.

[0112] A gun 27 is preferably associated with each section 31. Each gun 27 has its section for covering with slurry.

[0113] Furthermore, additional sensors (not shown) are preferably arranged above the movable support 7 for measuring the weight per square centimeter of the homogenized tobacco layer on the movable support 7 and the thickness of this tobacco layer. The sensors may for example be nuclear measuring heads. Additional sensors (still not shown in the drawings) are preferably present as well, such as sensors for locating and determining defects in the cast web of homogenized tobacco, sensors for determining the moisture content of the slurry and parallel sheets 10, and a temperature sensor for determining the temperature of the slurry in tank 4.

[0114] All sensors preferably send signals related to the respective parameter being measured (temperature, moisture slurry level, defects, etc.) to a central control unit 50 (see FIG. 1). The central control unit 50 is preferably electrically connected to one, some or all of the pumps 5, 24, actuators, motors 18, sensors 40, guns 27, flow meters 26, or to further circuits and actuators in the apparatus 2 or in the slurry preparation apparatus (not visible). If the sheet 10 reveals defects or inhomogeneities or if the properties of the sheet 10 are outside of pre-set ranges, the central control unit 50 can command changes in the process parameters, thus affecting the properties of the slurry or the parameters of the sheet formation. These process parameters may for example be the dimensions of the nozzle in the gun 27, the flow rate of the slurry, the temperature of the slurry, the shape of the spray, or the amount of slurry in the tank 4, or any combination of these.

[0115] The drying apparatus 3 includes a number of separate drying zones, each preferably including steam heating below the support and heated air above the movable support 7, and preferably also adjustable exhaust control. Within the drying apparatus 3, the homogenized tobacco web is dried onto the support 7 to the desired final moisture.

[0116] Now referring to FIG. 6, the function of the apparatus 1 including the sheet former 2 is as follows. Preferably, the slurry formed by mixing and combining the tobacco powder, water, and other ingredients is transferred in step 100 from a holding tank (not shown) to the sheet former 2 inside the tank 4, for example using an in-line mixer (also not shown). In step 101, the main valve 21 is opened and the slurry reaches the branch pipe 22. Thus, the guns 27 are operated in step 102 so that the slurry is fed onto the movable support 7, for example a stainless steel belt 7. Each gun 27 deposits the slurry onto a different section 31 realized in the movable support 7. Furthermore, any of the steps 100-102 preferably includes monitoring the level of the slurry in the tank 4, the moisture of the slurry inside the tank 4, and the density of the slurry by suitable sensors.

[0117] The thickness and basis weight of the sheet 10, controlled by a nuclear gauge immediately after the casting process, are continuously monitored and feedback controlled using a slurry measuring device. The formation of the sheet is carried out by guns 27 that spray or inject the slurry into different sectors 31 provided in a movable support 7. Due to the walls 30, the sheets remain separated during the transport.

[0118] Further, the sheet 10 undergoes a step 103 of drying by a drying device 3. The sheets 10 preferably move continuously on a movable support so that they enter the dryer together, therefore their drying is simultaneous. The drying step preferably involves uniform and gentle drying of the sheets in an endless stainless steel belt dryer with individually controllable zones. During drying, a step (not shown) of monitoring the temperature of the sheets in each drying zone is preferably carried out to ensure a gentle drying profile in each drying zone. The web is dried to the desired final moisture on a steel belt 7 using steam pan heating from the bottom and air drying on top. All drying zones are equipped with steam flow and pressure control, and air temperature and air flow are fully adjustable to provide the desired drying profile, ensuring that product residence times are respected.

[0119] At the end of the drying step 103, the sheet of homogenized tobacco material is preferably removed from the support 7, for example by a doctoring blade. Doctoring 104 of the sheet at the correct moisture content is preferably carried out after the drying station.

[0120] After drying step 103, the sheet 10 is preferably wound onto several "small" bobbins in a winding step 105. The bobbins may then be used for the manufacture of aerosol-generating articles (not shown).

Claims

1. 1. An apparatus for producing a plurality of sheets of an alkaloid-containing material, comprising: A tank adapted to contain the slurry having a plurality of outlets; a movable support adapted to move along a conveying direction; a plurality of separators positioned parallel to the conveying direction and in contact with the surface of the movable support, dividing the surface of the movable support into a number of sections, Apparatus wherein each of said plurality of outlets is located above a section.

2. The apparatus of claim 1 including a spray gun or an ejection gun at each of the plurality of outlets.

3. 3. The apparatus of claim 1 or claim 2, including a pressure regulator at each of the plurality of outlets.

4. An apparatus as claimed in any preceding claim, comprising a flow meter at each of said plurality of outlets.

5. The apparatus according to any one of claims 1 to 4, wherein the width of said sections in a direction perpendicular to said conveying direction is comprised between about 10 millimeters and about 300 millimeters.

6. The apparatus according to any one of claims 1 to 5, wherein the height of the separator in a direction perpendicular to the conveying direction is comprised between about 10 millimeters and about 100 millimeters.

7. An apparatus according to any preceding claim, wherein the size or shape of each of the plurality of outlets is variable.

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