Method for generating an aerosol generating element

Abstract

1. A method of producing aerosol-generating elements for an aerosol-generating article or system, comprising the steps of: preparing a matrix polymer solution in water comprising a matrix-forming polymer; adding a plurality of aerosol-generating formulation components to the matrix polymer solution to form an aerosol-generating solution, the aerosol-generating formulation components comprising a polyhydric alcohol and at least one alkaloid or cannabinoid; forming separate portions of the aerosol-generating solution; adding the separate portions of the aerosol-generating solution to a cross-linking solution of a polyvalent cation to cross-link the matrix-forming polymer; and removing the aerosol-generating elements from the cross-linking solution and drying the aerosol-generating elements.

Description

Technical Field

[0001] The present invention relates to a method for generating an aerosol generating element for use in an aerosol generating article or an aerosol generating system. The present invention further relates to an aerosol generating element produced by such a method.

Background Art

[0002] Aerosol generating articles in which an aerosol generating substrate such as a nicotine-containing substrate or a tobacco-containing substrate is heated rather than burned are known in the art. Typically, in such heated smoking articles, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol generating substrate or material, which may be in contact with the heat source, within the heat source, around the heat source, or downstream of the heat source. During use of the aerosol generating article, volatile compounds are released from the aerosol generating substrate by heat transfer from the heat source and entrained in the air drawn through the aerosol generating article. The released compounds condense as they cool to form an aerosol.

[0003] Numerous prior art documents disclose aerosol generating devices for consuming aerosol generating articles. Such devices include, for example, electrically heated aerosol generating devices in which an aerosol is generated by heat transfer from one or more electrical heater elements of the aerosol generating device to the aerosol generating substrate of a heated aerosol generating article.

[0004] Substrates for heated aerosol generating articles have heretofore often been produced using randomly oriented fragments, strands, or shreds of tobacco material. Alternatively, a rod for a heated aerosol generating article formed from an assembly of sheets of tobacco material is disclosed, for example, in International Patent Application No. WO-A-2012 / 164009.

[0005] International Patent Application WO-A-2011 / 101164 discloses an alternative rod for a heated aerosol-generating article formed from strands of homogenized tobacco material, which can be formed by casting, rolling, calendaring, or extruding a mixture comprising particulate tobacco and at least one aerosol former to form a sheet of homogenized tobacco material. In an alternative embodiment, the rod of International Patent Application No. WO-A-2011 / 101164 is formed from strands of homogenized tobacco material obtained by extruding a mixture comprising particulate tobacco and at least one aerosol former, and can form a continuous length of homogenized tobacco material.

[0006] Alternative forms of nicotine-containing substrates are also disclosed. As an example, liquid nicotine compositions, often referred to as e-liquids, have been proposed. These liquid compositions can be heated, for example, by a coiled electrically resistive filament of an aerosol-generating device. This type of substrate may require particular attention in the manufacture of a container for holding the liquid composition to prevent unwanted leakage.

[0007] It has previously been proposed to provide encapsulated nicotine formulations for use as aerosol-generating substrates. However, it has been found that encapsulation of nicotine formulations is difficult. One reason for this is that hydrophilic aerosol formers such as glycerin and propylene glycol in the nicotine formulation are preferred, which makes it difficult to encapsulate the formulation with commonly used hydrophilic encapsulation materials. It is generally known that very high levels of hydrophilic encapsulation material are required to produce a stable product with existing encapsulation techniques. This further means that an insufficient amount of nicotine formulation is provided per unit volume, resulting in inefficient aerosol delivery from the encapsulated substrate.

[0008] Hydrophobic encapsulation materials are available, but such materials often need to be processed at relatively high temperatures, which poses a risk of decomposition of the nicotine formulation during manufacture. During use, the temperature required to generate an aerosol from the nicotine formulation may be high enough to cause decomposition of the hydrophobic encapsulation material. This results in the release of undesirable compounds into the resulting aerosol, which can negatively affect the sensory profile of the aerosol.

[0009] It is desirable to provide a novel method for producing an encapsulated aerosol-generating formulation, such as a nicotine-containing formulation, that provides an improved encapsulated matrix with increased stability of the aerosol-generating formulation and minimal leakage thereof. It is desirable to provide a method for producing an encapsulated matrix having a payload of a maximum amount of aerosol-generating formulation with a minimum amount of encapsulation material so as to provide efficient aerosol delivery. Further, it is desirable to provide a method for producing an encapsulated matrix that provides controlled aerosol delivery with heating. It is further desirable to provide a method for producing an encapsulated matrix in a form that can be easily incorporated into and easily heated in an aerosol-generating article or device for generating an aerosol. Summary of the Invention

[0010] According to the present invention, there is provided a method for producing an aerosol generating element, comprising the steps of preparing a matrix polymer solution containing a matrix-forming polymer in water; adding a plurality of aerosol generating formulation components to the matrix polymer solution to form an aerosol generating solution, wherein the aerosol generating formulation components include a polyhydric alcohol and at least one alkaloid or cannabinoid; forming individual portions of the aerosol generating solution; adding the individual portions of the aerosol generating solution to a crosslinking solution of a polyvalent cation to crosslink the matrix-forming polymer, thereby forming an aerosol generating element having a continuous polymer matrix and an aerosol generating formulation containing aerosol generating formulation components dispersed within the continuous polymer matrix; and removing the aerosol generating element from the crosslinking solution and drying the aerosol generating element.

[0011] The method as defined forms an aerosol generating element having a continuous polymer matrix and an aerosol generating formulation containing aerosol generating formulation components dispersed within the continuous polymer matrix.

[0012] According to the present invention, there is further provided an aerosol generating element produced by the method of the present invention as defined above, comprising at least 60 weight percent polyhydric alcohol, at least 0.5 weight percent nicotine, and at least 0.5 weight percent acid.

[0013] As used herein, the term "aerosol generating article" refers to an article for generating an aerosol for the generation of an aerosol comprising an aerosol generating substrate that is intended to be heated, rather than combusted, to release a volatile compound capable of forming an aerosol.

[0014] As used herein, the term "aerosol generating element" refers to an individual aerosol generating substrate in solid form comprising an aerosol generating formulation dispersed and encapsulated within a crosslinked polymer matrix. The structure and composition of the aerosol generating element will be described in more detail below.

[0015] The aerosol generating element according to the present invention can find use as an aerosol generating substrate for aerosol generating articles.

[0016] As used herein, the term "aerosol generating substrate" refers to a substrate having the ability to release a volatile compound capable of forming an aerosol upon heating. In the present invention, the aerosol generating substrate is in the form of an aerosol generating element that encapsulates an aerosol generating formulation containing at least one alkaloid or cannabinoid, and a polyhydric alcohol. The aerosol generated from the aerosol generating formulation of the aerosol generating element described herein is a dispersion of solid particles or droplets (or a combination of solid particles and droplets) in a gas. The aerosol may be visible or invisible and may include vapors of substances that are usually liquid or solid at room temperature, as well as solid fine particles, or droplets, or a combination of solid fine particles and droplets.

[0017] Conventional cigarettes are ignited when a user applies a source of ignition to one end of the cigarette and draws air through the other end. The localized heat provided by the flame and oxygen in the air drawn through the cigarette ignites the end of the cigarette, and the resulting combustion generates smoke that can be inhaled. In contrast, in heated aerosol generating articles, the aerosol is generated by heating a flavor generating substrate such as, for example, a tobacco-derived substrate, or a substrate containing an aerosol former and flavorants. Known heated aerosol generating articles include, for example, electrically heated aerosol generating articles and aerosol generating articles in which the aerosol is generated by heat transfer from a combustible fuel element or heat source to an aerosol forming material physically separated therefrom.

[0018] For example, the aerosol-generating article according to the present invention may have a particular use in an aerosol generation system comprising an electrically heated aerosol generator having an internal heater adapted to supply heat to one or more individual aerosol-generating substrate elements. As used herein with respect to the present invention, the term "aerosol generator" is used to describe a device comprising a heater element that interacts with one or more aerosol-generating elements according to the present invention to generate an aerosol. In use, the volatile compound is released from the aerosol-generating element by heat transfer and entrained in the air drawn through the aerosol-generating article. The released compound condenses as it cools to form an aerosol, which is inhaled by the consumer.

[0019] The substrate for a heated aerosol-generating article typically comprises an "aerosol former", i.e. a compound or mixture of compounds that facilitates the formation of an aerosol during use and is preferably substantially resistant to thermal decomposition at the operating temperature of the aerosol-generating article. Examples of suitable aerosol formers include polyhydric alcohols (such as propylene glycol, triethylene glycol, 1,3-butanediol, glycerol), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate).

[0020] The polyhydric alcohol in the aerosol-generating formulation of the aerosol-generating element produced according to the present invention is also an aerosol former within the meaning described above.

[0021] As used herein, the term "aerosol-generating formulation" refers to a formulation comprising a plurality of aerosol-generating formulation components that volatilize upon heating of the aerosol-generating element to generate an aerosol. The "aerosol-generating solution" produced during the method of the present invention refers to a solution of aerosol-generating formulation components and matrix-forming polymers in a suitable solvent.

[0022] As used herein, the term "matrix-forming polymer" refers to a polymeric form of encapsulating material that has the ability to generate a three-dimensional polymer matrix as a result of cross-linking when the matrix-forming polymer is contacted with a cross-linking solution of polyvalent cations. The resulting polymer matrix has the ability to capture and retain the aerosol-generating formulation within its cross-linked structure. The properties of the cross-linked polymer matrix are described in more detail below.

[0023] As described above, the present invention provides a novel method for generating an aerosol-generating element in which an aerosol-generating formulation is encapsulated within a continuous polymer matrix structure. The aerosol-generating element produced by the present invention provides a stable structure that can effectively retain the aerosol-generating formulation while minimizing loss of aerosol-generating formulation components during the manufacture or storage of the aerosol-generating element.

[0024] Advantageously, the method according to the present invention enables effective encapsulation of the aerosol-generating formulation using a much lower level of encapsulating material (corresponding to the matrix-forming polymer) than was previously possible. This makes it possible to maximize the levels of alkaloids or cannabinoids, and aerosol-generating formulation components such as polyhydric alcohols, within the aerosol-generating element. Furthermore, the reduction in the proportion of encapsulating material required means that less heating of the encapsulating material is needed, enabling more efficient aerosol generation upon heating.

[0025] The polymer matrix of the aerosol generating element provides an inert encapsulation structure for retaining and fixing the aerosol generating formulation, which is stable upon heating of the aerosol generating element during use. The inventors have found that when heated to a temperature of 150 °C to 350 °C, the aerosol generating elements produced according to the present invention release aerosol upon undergoing significant weight loss. However, this weight loss is not accompanied by a similarly significant volume loss. Without wishing to be bound by theory, it will be understood that upon heating, the components of the aerosol generating formulation originally dispersed and trapped within the continuous polymer matrix structure are substantially evaporated and released. On the other hand, the components of the continuous polymer matrix structure are substantially unaffected and the continuous polymer matrix only shrinks partially while essentially retaining its 3D structure. Thus, the encapsulation of the aerosol generating formulation within the polymer-derived matrix advantageously provides minimal or no adverse effect on the sensory profile of the aerosol generated upon heating.

[0026] The aerosol generating elements produced by the method of the present invention have been found to advantageously provide a controlled delivery of aerosol. Furthermore, the aerosol delivery profile can be readily adjusted by controlling different parameters of the production method. For example, the aerosol delivery profile can be adjusted by changing the method for controlling parameters of the aerosol generating element such as the size, shape, structure and formulation of the aerosol generating element.

[0027] The aerosol generating element is in the form of an individual, self-standing solid object that is sufficiently stable and robust and can be readily processed and introduced into aerosol generating articles using existing methods and techniques.

[0028] As defined above, in the method of generating an aerosol generating element, first, an aerosol generating solution is prepared from a matrix polymer solution and aerosol generating formulation components. Next, individual portions of the aerosol generating solution are added to a crosslinking solution, resulting in crosslinking of the matrix-forming polymer and formation of a polymer matrix. The resulting aerosol generating element is removed from the crosslinking solution and dried. Each of the method steps is described in more detail here.

[0029] In the first step of the method of the present invention, a matrix polymer solution, which is a solution of a matrix-forming polymer, is formed in water. The matrix polymer solution preferably contains at least about 35 weight percent water, more preferably at least about 40 weight percent water. This level of water ensures that the matrix-forming polymer is sufficiently dissolved so that a homogeneous solution is provided.

[0030] The matrix polymer solution preferably contains at least about 40 weight percent of the matrix-forming polymer, more preferably at least about 45 weight percent of the matrix-forming polymer. This level of the matrix-forming polymer has been found to provide a more stable aerosol generating solution.

[0031] The matrix-forming polymer may be a single polymer or a combination of two or more polymers, and one or more of the polymers have the ability to form a crosslinked matrix through an ionotropic gelation mechanism in a crosslinking solution of a polyvalent cation. Crosslinking of the matrix-forming polymer is achieved through the reaction of the polymer and the polyvalent cation in the crosslinking solution, which forms salt bridges for crosslinking the polymer molecules.

[0032] Suitable matrix-forming polymers are known to those skilled in the art. The matrix-forming polymer preferably contains one or more polysaccharides such as alginate or pectin, or a combination thereof. It is particularly preferred that the matrix-forming polymer is alginate. The polysaccharide can be made water-insoluble and thermally stable by cross-linking, and is also tasteless, so it is particularly suitable for use in the present invention. Therefore, it does not adversely affect the sensory properties of the aerosol generated from the aerosol generating element.

[0033] Alternative matrix-forming polymers suitable for use in the method according to the present invention include, but are not limited to, chitosan, fibrin, collagen, gelatin, hyaluronic acid, dextran, and combinations thereof.

[0034] Alternative matrix-forming polymers suitable for use in the method according to the present invention can be constructed from one or more of the following monomers and polymers: hydroxyethyl methacrylate (HEMA), N-(2-hydroxypropyl) methacrylate (HPMA), N-vinyl-2-pyrrolidone (NVP), N-isopropylacrylamide (NIPAMM), vinyl acetate (VAc), acrylic acid (AA), methacrylic acid (MAA), polyethylene glycol acrylate / methacrylate (PEGA / PEGMA), and polyethylene glycol diacrylate / dimethacrylate, (PEGDA / PEGDMA).

[0035] After the formation of the above matrix polymer solution, a plurality of aerosol generating formulation components are added to the matrix polymer solution to form an aerosol generating solution. The aerosol generating formulation components include at least one alkaloid or cannabinoid, and a polyhydric alcohol. The aerosol generating formulation components preferably further contain an acid. These components will be described in more detail below. Therefore, the aerosol generating solution is a solution containing a matrix-forming polymer and aerosol generating formulation components.

[0036] The aerosol generating solution preferably contains a matrix-forming polymer from at least about 1 weight percent of a matrix polymer solution, more preferably contains at least about 1.5 weight percent of a matrix-forming polymer, and even more preferably contains at least about 2 weight percent of a matrix-forming polymer.

[0037] The aerosol generating solution preferably contains less than about 6 weight percent of a matrix-forming polymer from a matrix polymer solution, more preferably contains less than about 5 weight percent of a matrix-forming polymer, and even more preferably contains less than about 4 weight percent of a matrix-forming polymer.

[0038] For example, the aerosol generating solution can contain from about 1 weight percent to about 6 weight percent of a matrix-forming polymer, or from about 1.5 weight percent to about 5 weight percent of a matrix-forming polymer, or from about 2 weight percent to about 4 weight percent of a matrix-forming polymer.

[0039] For example, in a preferred embodiment, the aerosol generating solution can contain from about 1 weight percent to about 6 weight percent of alginate, or from about 1.5 weight percent to about 5 weight percent of alginate, or from about 2 weight percent to about 4 weight percent of alginate.

[0040] The aerosol generating formulation components may be added to the matrix polymer solution individually and sequentially. In some cases, it is desirable to control the order or sequence in which the components are added to the matrix polymer solution in order to control the viscosity of the aerosol generating solution, as described in more detail below.

[0041] Alternatively, two or more aerosol generating formulation components may be combined together before being added to the matrix polymer solution, and the combination of aerosol generating formulation components is then added to the matrix polymer solution. All of the aerosol generating formulation components may be combined together before being added to the matrix polymer solution, or only some of the aerosol generating formulation components may be combined together and the remainder added individually and separately to the matrix polymer solution. In the latter case, the order of addition of the aerosol generating formulation components may still be controlled as described herein.

[0042] In one preferred embodiment of the present invention, the aerosol generating solution is formed by adding a liquid nicotine formulation to the matrix polymer solution, the liquid nicotine formulation comprising nicotine and a polyhydric alcohol. Optionally, the liquid nicotine formulation further comprises an acid. The liquid nicotine formulation may be in the form of, for example, an e-liquid formulation. When the liquid nicotine formulation is added to the matrix polymer solution, an additional amount of nicotine, or an acid, or both nicotine and an acid may then be added to the matrix polymer solution to produce the aerosol generating solution. In this case, the order of addition of the liquid nicotine formulation and the additional nicotine and acid may be controlled as described above. For example, when an additional amount of acid is added to the matrix polymer solution, the acid is preferably added after the liquid nicotine formulation and any additional nicotine. Advantageously, this embodiment may provide a method for incorporating a tobacco extract into the matrix polymer solution so as to be incorporated into the aerosol generating element.

[0043] In certain embodiments of the present invention, it may be desirable to control the viscosity of the aerosol-generating solution. This may involve controlling the viscosity of the matrix polymer solution when the aerosol-generating formulation components are added. For example, depending on the technique used to produce individual portions of the aerosol-generating solution in subsequent steps of the method, it may be preferable to provide an aerosol-generating solution having a viscosity within a particular range. Different techniques are likely to be facilitated by different viscosity solutions, and the appropriate viscosity should be determined according to the technique used.

[0044] As described below, in embodiments where individual portions of the aerosol-generating solution are produced by a gravity-drop process, the viscosity of the solution is preferably kept below about 5000 mPa·s. This enables the formation of droplets of the aerosol-generating solution under gravity and also enables the beads to reach a stable shape in the cross-linking solution before the cross-linking cures the solution to fix the final shape of the aerosol-generating element.

[0045] In the case of the gravity-drop method, the viscosity of the aerosol-generating solution is from about 100 mPa·s (millipascal seconds) to about 4000 mPa·s, more preferably from about 2500 mPa·s to about 3000 mPa·s. For the purposes of the present invention, the viscosity of the aerosol-generating solution can be measured using a torque-rotational viscometer such as a Fungilab Viscolead ADV(L) having the following parameters: a liquid volume of 10 mL, a temperature of 25 degrees Celsius, and a rotational speed of 10 to 15 rpm. A test method suitable for measuring viscosity is described in ASTM D2983-19, "Standard Test Method for Low Temperature Exactivity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants using a Rotational Viscometer".

[0046] In certain embodiments, it may be preferable to control the pH of the matrix polymer solution while aerosol-generating formulation components are added in order to control the viscosity of the aerosol-generating solution. This is because in some matrix polymer solutions, pH can affect viscosity. For example, in embodiments of the present invention where the matrix-forming polymer comprises alginate, it is preferable to maintain the pH of the solution above pH 4. This is intended to avoid gelation of the alginate that can occur at pH levels below pH 4, for example due to hydrogen bonding. Such gelation at low pH causes an undesirable increase in the viscosity of the aerosol-generating solution, which makes it difficult to use certain techniques such as gravity dropping to form the aerosol-generating element.

[0047] In such embodiments where it is preferable to control the pH of the matrix polymer solution when aerosol-generating formulation components are added, the aerosol-generating formulation components are preferably added sequentially to maintain the pH above a specific pH value. For example, if the matrix-forming polymer comprises alginate, the aerosol-generating formulation components are preferably added sequentially to maintain the pH of the matrix polymer solution above pH 4 as described above. If the aerosol-generating formulation component comprises an acid, the acid is preferably added last to maintain the pH of the matrix polymer solution at a relatively high level. If the aerosol-generating formulation component comprises nicotine, nicotine is preferably added first before other aerosol-generating formulations are added to obtain a basic pH of the matrix polymer solution.

[0048] Alternatively, or in addition, the viscosity of the aerosol-generating solution may be controlled by adjusting the concentration of the solution. For example, the proportion of water in the aerosol-generating solution can be adjusted to adjust the viscosity. The aerosol-generating solution preferably contains at least about 35 weight percent water to maintain an appropriate viscosity. The aerosol-generating solution particularly preferably contains from about 35 weight percent to about 65 weight percent water.

[0049] According to a preferred embodiment of the present invention, there is provided a method for producing an aerosol generating element, comprising the steps of: preparing a matrix polymer solution containing a matrix-forming polymer in water; adding a plurality of aerosol generating formulation components to the matrix polymer solution to form an aerosol generating solution, wherein the aerosol generating formulation components include a polyhydric alcohol, at least one alkaloid or cannabinoid, and an acid, and the aerosol generating formulation components are sequentially added to the matrix polymer solution such that the acid is added after the other aerosol generating formulation components; forming droplets of one or more aerosol generating solutions; dropping the droplets of one or more aerosol generating solutions into a crosslinking solution of a polyvalent cation to crosslink the matrix-forming polymer, thereby forming an aerosol generating element having a continuous polymer matrix and aerosol generating formulation components dispersed within the continuous polymer matrix; removing the aerosol generating element from the crosslinking solution; and drying the aerosol generating element.

[0050] The method as defined forms an aerosol generating element having a continuous polymer matrix and an aerosol generating formulation containing aerosol generating formulation components dispersed within the continuous polymer matrix.

[0051] As defined above, the aerosol generating solution contains a polyhydric alcohol as one of the aerosol generating formulation components. The polyhydric alcohol acts as an aerosol former in the aerosol generating element.

[0052] Polyhydric alcohols suitable for use in aerosol generating elements include, but are not limited to, propylene glycol, triethylene glycol, 1,3 - butanediol, and glycerin. In the aerosol generating elements produced according to the present invention, the polyhydric alcohol is preferably selected from the group consisting of glycerin, propylene glycol, and combinations thereof. In a particularly preferred embodiment, the polyhydric alcohol is glycerin.

[0053] The concentration of the polyhydric alcohol in the aerosol generating solution is selected such that the level of the polyhydric alcohol in the final aerosol generating element is high enough to produce an acceptable aerosol. The aerosol generating solution preferably contains at least about 20 weight percent of the polyhydric alcohol, more preferably at least about 25 weight percent of the polyhydric alcohol, more preferably at least about 30 weight percent of the polyhydric alcohol, and more preferably at least about 35 weight percent of the polyhydric alcohol.

[0054] The aerosol generating solution preferably contains less than about 60 weight percent of the polyhydric alcohol, more preferably less than about 55 weight percent of the polyhydric alcohol, more preferably less than about 50 weight percent of the polyhydric alcohol, and more preferably less than about 45 weight percent of the polyhydric alcohol.

[0055] For example, the aerosol generating solution can contain from about 20 weight percent to about 60 weight percent of the polyhydric alcohol, or from about 25 weight percent to about 55 weight percent of the polyhydric alcohol, or from about 30 weight percent to about 50 weight percent of the polyhydric alcohol, or from about 35 weight percent to about 45 weight percent of the polyhydric alcohol.

[0056] As defined above, the aerosol generating solution further contains at least one alkaloid or cannabinoid compound as one of the aerosol generating formulation components.

[0057] As used herein in connection with the present invention, the term "alkaloid compound" means any one class of naturally occurring organic compounds containing one or more basic nitrogen atoms. Generally, alkaloids contain at least one nitrogen atom in an amine-type structure. This nitrogen atom or another nitrogen atom within the molecule of an alkaloid compound can be active as a base in an acid-base reaction. Most alkaloid compounds have one or more of their nitrogen atoms as part of a cyclic system, such as a heterocyclic ring. In nature, alkaloid compounds are mainly found in plants and are particularly common in certain families of flowering plants. However, some alkaloid compounds are found in animal species and fungi. In the context of the present invention, the term "alkaloid compound" is used to describe both naturally derived alkaloid compounds and synthetically produced alkaloid compounds.

[0058] The alkaloid is preferably selected from the group consisting of nicotine, anatabine, and combinations thereof.

[0059] As used herein in connection with the present invention, the term "cannabinoid compound" describes any one type of natural compound found in the Cannabis plant, namely Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Cannabinoid compounds are particularly concentrated in the female flower heads. Natural cannabinoid compounds in the Cannabis plant include tetrahydrocannabinol (THC) and cannabidiol (CBD). In the context of the present invention, the term "cannabinoid compound" is used to describe both naturally derived cannabinoid compounds and synthetically produced cannabinoid compounds.

[0060] The aerosol-generating formulation components preferably include a cannabinoid compound selected from the group consisting of tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabigerol monomethyl ether (CBGM), cannabivarin (CBV), cannabidivarin (CBDV), tetrahydrocannabivarin (THCV), cannabichromene (CBC), cannabicyclol (CBL), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabinergsoin (CBE), cannabinicitran (CBT), and combinations thereof.

[0061] Generally, the level of the alkaloid compound or cannabinoid compound in the aerosol-generating solution can be selected such that the aerosol-generating element contains up to about 10 weight percent of the alkaloid compound, or the cannabinoid compound, or both. The content of the alkaloid compound, or the cannabinoid compound, or both in the aerosol-generating element may be increased and adjusted from the perspective of optimizing the delivery of the alkaloid compound, or the cannabinoid compound, or both to the consumer in aerosol form. Compared to existing aerosol-generating substrates based on the use of plant materials, this may advantageously allow for a higher content of the alkaloid compound, or the cannabinoid compound, or both per volume or per weight of the substrate, which may be desirable from a manufacturing perspective.

[0062] The aerosol-generating solution preferably contains at least about 0.5 weight percent of the alkaloid compound, or the cannabinoid compound, or both. Thus, the aerosol-generating solution preferably contains at least about 0.5 weight percent of the alkaloid compound, or at least 0.5 weight percent of the cannabinoid compound, or at least about 0.5 weight percent of a combination of the alkaloid compound and the cannabinoid compound.

[0063] The aerosol generating solution preferably contains at least about 1 weight percent of an alkaloid compound, or a cannabinoid compound, or both, and more preferably contains at least about 2 weight percent of an alkaloid compound, or a cannabinoid compound, or both. The aerosol generating solution preferably contains less than about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both, more preferably contains less than about 8 weight percent of an alkaloid compound, or a cannabinoid compound, or both, and even more preferably contains less than about 6 weight percent of an alkaloid compound, or a cannabinoid compound, or both.

[0064] For example, the aerosol generating solution can contain from about 0.5 weight percent to about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both, or from about 1 weight percent to about 8 weight percent of an alkaloid compound, or a cannabinoid compound, or both, or from about 2 weight percent to about 6 weight percent of an alkaloid compound, or a cannabinoid compound, or both.

[0065] In some embodiments, the aerosol generating formulation component contains one or more of cannabinoid and alkaloid compounds including nicotine or anatabine. In some preferred embodiments, the aerosol generating solution contains nicotine.

[0066] As used herein in connection with the present invention, the term "nicotine" is used to describe nicotine, nicotine base, or nicotine salts. In embodiments where the aerosol generating formulation component contains nicotine base or nicotine salts, the amounts of nicotine recited herein are the amounts of free base nicotine or protonated nicotine, respectively.

[0067] The aerosol generating formulation component may contain natural nicotine or synthetic nicotine.

[0068] The aerosol generating formulation components may include one or more monobasic nicotine salts.

[0069] As used herein with respect to the present invention, the term "monobasic nicotine salt" is used to describe a nicotine salt of a monobasic acid.

[0070] The aerosol generating solution preferably contains at least about 0.5 weight percent nicotine. More preferably, the aerosol generating solution contains at least about 1 weight percent nicotine. Even more preferably, the aerosol generating solution contains at least about 2 weight percent nicotine. Additionally, or alternatively, the aerosol generating solution preferably contains less than about 10 weight percent nicotine. More preferably, the aerosol generating solution contains less than about 8 weight percent nicotine. Even more preferably, the aerosol generating solution contains less than about 6 weight percent nicotine. For example, the aerosol generating solution can contain from about 0.5 weight percent to about 10 weight percent nicotine, or from about 1 weight percent to about 8 weight percent nicotine, or from about 2 weight percent to about 6 weight percent nicotine.

[0071] The amount of nicotine in the aerosol generating solution is preferably adjusted to provide an aerosol generating element that contains at least about 0.5 milligrams of nicotine, more preferably at least about 1 milligram of nicotine, more preferably at least about 1.5 milligrams of nicotine, more preferably at least about 2 milligrams of nicotine, and most preferably at least about 2.5 milligrams of nicotine.

[0072] The aerosol generating element can contain up to about 6 milligrams of nicotine. Thus, preferably, the amount of nicotine in the aerosol generating solution is adjusted to provide an aerosol generating element that contains about 6 milligrams or less of nicotine, more preferably about 5 milligrams or less of nicotine, more preferably about 4 milligrams or less of nicotine, more preferably about 3.5 milligrams or less of nicotine, and most preferably about 3 milligrams or less of nicotine.

[0073] In some preferred embodiments, the aerosol generating formulation components include a cannabinoid compound. The cannabinoid compound is preferably selected from CBD and THC. More preferably, the cannabinoid compound is CBD.

[0074] The aerosol generating solution may contain up to about 10 weight percent of CBD. Preferably, the aerosol generating solution contains at least about 0.5 weight percent of CBD, more preferably at least about 1 weight percent of CBD, and even more preferably at least about 2 weight percent of CBD. Preferably, the aerosol generating solution contains less than about 8 weight percent of CBD, more preferably less than about 6 weight percent of CBD.

[0075] For example, the aerosol generating solution can contain from about 0.5 weight percent to about 10 weight percent of CBD, more preferably from about 1 weight percent to about 8 weight percent of CBD, and even more preferably from about 2 weight percent to about 6 weight percent of CBD.

[0076] As described above, in a preferred embodiment of the present invention, the aerosol generating formulation components further include an acid.

[0077] More preferably, the aerosol generating formulation components include one or more organic acids. Even more preferably, the aerosol generating formulation components include one or more carboxylic acids.

[0078] Carboxylic acids suitable for use in the aerosol generating formulation of the aerosol generating element according to the present invention include, but are not limited to, 2-ethylbutyric acid, acetic acid, adipic acid, benzoic acid, butyric acid, cinnamic acid, cycloheptanecarboxylic acid, fumaric acid, glycolic acid, hexanoic acid, lactic acid, levulinic acid, malic acid, myristic acid, octanoic acid, oxalic acid, propanoic acid, pyruvic acid, succinic acid, and undecanoic acid.

[0079] In a particularly preferred embodiment, the acid is lactic acid, or levulinic acid, or benzoic acid, or levulinic acid, or fumaric acid, or acetic acid. Most preferably, the acid is lactic acid. Inclusion of the acid is particularly preferred in embodiments where the aerosol-generating formulation components include nicotine, since it has been observed that the presence of the acid can stabilize dissolved species in the aerosol-generating solution, such as nicotine and other plant extracts. Without wishing to be bound by theory, it is understood that the acid interacts with nicotine molecules such that protonated nicotine is stabilized. Since protonated nicotine is non-volatile, it is more readily seen in the liquid or particulate phase rather than in the vapor phase of the aerosol obtained by heating the aerosol-generating element. As such, loss of nicotine during manufacture of the aerosol-generating element can be minimized, and advantageously, higher and better controlled nicotine delivery to the consumer can be ensured.

[0080] The aerosol-generating solution preferably contains at least about 0.5 weight percent acid. More preferably, the aerosol-generating solution contains at least about 1 weight percent acid. Even more preferably, the aerosol-generating solution contains at least about 2 weight percent acid. Additionally or alternatively, the aerosol-generating solution preferably contains less than about 10 weight percent acid. More preferably, the aerosol-generating solution contains less than about 8 weight percent acid. Even more preferably, the aerosol-generating solution contains less than about 6 weight percent acid.

[0081] For example, the aerosol-generating solution may contain from about 0.5 weight percent to about 10 weight percent acid, or from about 1 weight percent to about 8 weight percent acid, or from about 2 weight percent to about 6 weight percent acid.

[0082] When the aerosol-generating solution contains nicotine, the molar ratio of acid to nicotine is preferably from about 0.5:1 to about 2:1, more preferably from about 0.75:1 to about 1.5:1, and most preferably about 1:1.

[0083] When polyacids such as polycarboxylic acids are used, it may be preferable to provide a molar ratio of acid groups to nicotine of about 0.5:1 to about 2:1, more preferably about 0.75:1 to about 1.5:1, and most preferably about 1:1. Thus, the use of polyacids makes it possible to use less weight of acid while still providing the same level of protonation of nicotine.

[0084] The aerosol generating formulation components contained in the aerosol generating solution may optionally further contain a flavoring agent. The flavoring agent can be in liquid form or solid form. Optionally, the flavoring agent may be provided in microencapsulated form and the flavoring agent is released upon heating. The amount of flavoring agent in the aerosol generating solution is preferably adjusted to provide a desired level of flavoring agent within the aerosol generating element. Preferably, the aerosol generating element has a level of flavoring agent of about 0.05 weight percent to about 1 weight percent, more preferably about 0.1 weight percent to about 0.5 weight percent.

[0085] Suitable flavoring agents for use as aerosol generating formulation components in the present invention include, but are not limited to, mint such as tobacco, menthol, peppermint or spearmint, cocoa, licorice, fruits (such as citrus fruits), gamma-octalactone, vanilla, spices (such as cinnamon), methyl salicylate, linalool, eugenol, eucalyptol, bergamot oil, eugenol oil, geranium oil, lemon oil, ginger oil, and tobacco flavor.

[0086] Optionally, the aerosol generating solution may further include a plurality of susceptor particles. The susceptor particles are conductive particles having the ability to convert electromagnetic energy and convert it into heat. Eddy currents are induced in the susceptor particles when located in an alternating electromagnetic field, and hysteresis losses occur, causing heating of the susceptor. Since the susceptor particles are in thermal contact or in close thermal proximity to the aerosol generating formulation of the aerosol generating element, the aerosol generating formulation is heated by the susceptor particles so that an aerosol is formed.

[0087] Accordingly, including susceptor particles in the aerosol generating solution provides an aerosol generating element that can be inductively heated. When the aerosol generating element is used in an apparatus equipped with an induction heater, the change in the electromagnetic field generated by one or some of the induction coils of the induction heating device heats the susceptor particles, which then transfer heat to the aerosol generating formulation surrounding the aerosol generating element, mainly by heat conduction.

[0088] The susceptor particles can be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol generating formulation. Preferred susceptor particles include metal or carbon. Preferred susceptor particles may include ferromagnetic materials, such as ferromagnetic alloys, ferrite iron, or ferromagnetic steel, or stainless steel, or may consist of such ferromagnetic materials. Suitable susceptor particles may be aluminum or may include aluminum. Preferred susceptor particles may be heated to a temperature above 250 degrees Celsius. Suitable susceptor particles may include a non-metallic core having a metal layer disposed thereon, such as a metal track formed on the surface of a ceramic core. The susceptor particles may have a protective outer layer, such as a protective ceramic layer or a protective glass layer encapsulating the susceptor particles. The susceptor particles may include a protective coating formed of glass, ceramic, or an inert metal formed on top of the core of the susceptor material.

[0089] The susceptor particles can have an average particle size of up to about 60 micrometers. For example, the susceptor particles can have an average particle size of about 50 micrometers or less, or about 40 micrometers or less, or about 35 micrometers or less.

[0090] Typically, in the aerosol generating solution used in the method according to the present invention, the susceptor particles have an average particle size of at least about 1 micrometer, or at least about 2 micrometers, or at least about 5 micrometers, or at least about 10 micrometers.

[0091] For example, the susceptor particles in the aerosol generating solution can have an average particle size of from about 1 micrometer to about 60 micrometers, or from about 2 millimeters to about 50 micrometers, or from about 5 micrometers to about 40 micrometers, or from about 10 micrometers to about 35 micrometers.

[0092] Optionally, a solid filler may be additionally added to the aerosol generating solution. Inclusion of a solid filler can advantageously improve the physical properties of the resulting aerosol generating element. The solid filler may also be used to control the properties of the aerosol generating solution during the process of forming the individual portions of the aerosol generating solution. Suitable solid fillers are known to those skilled in the art.

[0093] For example, in certain embodiments of the present invention, the aerosol generating solution further comprises particles of plant material obtained by grinding, pulverizing, or subdividing the plant material. As an example, the aerosol generating solution may further comprise tea particles, coffee particles, cannabis particles, clove particles, eucalyptus particles, star anise particles, or ginger particles. Additionally, or alternatively, the aerosol generating solution may further comprise particles obtained by grinding, pulverizing, or subdividing one or more of the lamina of the tobacco leaf and the stem of the tobacco leaf. The inventors of the present invention have found that by incorporating such plant particles into the aerosol generating element, it is possible to advantageously produce an aerosol that provides a novel sensory experience. Such aerosols may provide a unique flavor and an increased level of richness.

[0094] In embodiments where the aerosol generating solution comprises plant particles, the amount of plant particles in the aerosol generating solution is adjusted to provide a desired level of plant particles within the aerosol generating element and a desired level of flavoring agent within the generated aerosol. The aerosol generating element may comprise up to about 40 weight percent of plant particles. Preferably, the aerosol generating element comprises 35 weight percent or less of plant particles. More preferably, the aerosol generating element comprises 30 weight percent or less of plant particles. Even more preferably, the aerosol generating element comprises 25 weight percent or less of plant particles.

[0095] In some embodiments, the aerosol generating element comprises at least about 1 weight percent of plant particles. Preferably, the aerosol generating element comprises at least about 2 weight percent of plant particles. More preferably, the aerosol generating element comprises at least about 5 weight percent of plant particles. Even more preferably, the aerosol generating element comprises at least about 10 weight percent of plant particles.

[0096] For example, the aerosol generating substrate can contain from about 1 weight percent to about 40 weight percent of plant particles, more preferably from about 2 weight percent to about 35 weight percent of plant particles, more preferably from about 5 weight percent to about 30 weight percent of plant particles, and most preferably from about 10 weight percent to about 25 weight percent of plant particles.

[0097] By providing an amount of plant particles within this range, it is ensured that sufficient flavor can be achieved from the plant particles without unduly affecting the consistency of the aerosol generating solution such that the processing of the aerosol generating solution for forming the aerosol generating element is adversely affected.

[0098] In embodiments where the aerosol generating solution contains plant particles, the plant particles can have an average particle size of up to about 60 micrometers. Preferably, the plant particles have an average particle size of about 50 micrometers or less, more preferably about 40 micrometers or less, and most preferably about 35 micrometers or less.

[0099] Typically, in the aerosol generating solution used in the method according to the present invention, the plant particles have an average particle size of at least about 1 micrometer, more preferably at least about 2 micrometers, more preferably at least about 5 micrometers, and most preferably at least about 10 micrometers.

[0100] For example, the plant particles in the aerosol generating solution can have an average particle size of from about 1 micrometer to about 60 micrometers, more preferably from about 2 millimeters to about 50 micrometers, more preferably from about 5 micrometers to about 40 micrometers, and most preferably from about 10 micrometers to about 35 micrometers.

[0101] In the next step of the method according to the present invention, after the formation of the aerosol-generating solution, individual portions of the aerosol-generating solution are formed. An "individual portion" of the solution typically corresponds to a specific volume of the solution that is processed to provide an aerosol-generating element having a specific shape and size. The individual portions of the aerosol-generating solution can be formed into various shapes depending on the desired form of the aerosol-generating element. For example, the aerosol-generating solution may be formed into a spherical or cylindrical shape to produce droplets, beads or threads of material. Alternatively, the aerosol-generating solution may be formed into a sheet, cut into strips or flakes, or drawn into elongated filaments or threads.

[0102] In a particularly preferred embodiment of the present invention, the step of forming the individual portions of the aerosol-generating solution includes forming droplets. The droplets of the aerosol-generating solution are preferably formed using a dropping process in which the aerosol-generating solution is dropped from an extrusion orifice or nozzle. The nozzle may optionally be connected to a pump. Particularly preferably, the droplets of the aerosol-generating solution are formed using a gravity dropping process in which each droplet falls from the extrusion nozzle only under gravity. Alternatively, the extrusion nozzle may be vibrated to assist in the formation and release of the droplets.

[0103] In a preferred embodiment of the present invention in which the droplets are formed using a dropping process, the diameter of the droplets can be adjusted through adjustment of the diameter of the extrusion nozzle, the viscosity of the aerosol-generating solution, or both. An extrusion nozzle having an opening with a diameter of from about 0.5 mm to about 6 mm is preferred to produce an aerosol-generating element having a suitable size for use in an aerosol article or system.

[0104] Typically, in such embodiments, when released from the extrusion nozzle, the droplets fall under gravity into the crosslinking solution. The droplets are preferably formed at a height of at least 0.1 meter above the crosslinking solution. This minimum dropping height is advantageous, for example, when spherical droplets are desired, to ensure that the droplets fall a sufficient distance to form a spherical shape. The droplets are preferably formed at a height less than 0.6 meter above the crosslinking solution so as to minimize deformation of the droplets before entering the crosslinking solution.

[0105] In certain embodiments, the dropping process can be combined with a jet breakup process, which breaks up the droplets or stream of the aerosol generating solution as it exits the nozzle to form smaller droplets. For example, a jet cutting device such as a rotating disk may be provided under the extrusion nozzle to break up the aerosol generating solution into droplets. This type of process is particularly suitable when an aerosol generating element having a relatively small diameter is desired.

[0106] Alternatively, an electrostatic extrusion process may be used in which the flow of the aerosol generating solution from the extrusion nozzle is separated by an electrostatic charge. Similar to the jet cutting process, electrostatic extrusion may be particularly suitable for the preparation of aerosol generating elements having a relatively small diameter. As a further alternative, the aerosol generating solution may be broken up by vibration means provided at or near the nozzle.

[0107] As described above, the desired viscosity of the aerosol generating solution depends to some extent on the selected process for forming the individual parts of the aerosol generating solution. An appropriate range of viscosities is shown for the gravity dropping process. Jet cutting may be suitable for aerosol generating solutions having a relatively high viscosity, for example, above 200 mPa·s. In contrast, electrostatic extrusion may be more suitable for aerosol generating solutions having a low viscosity, for example, less than 200 mPa·s.

[0108] Once formed, the individual portions of the aerosol-generating solution, preferably in the form of droplets, are added to the crosslinking solution of the polyvalent cation. Thereby, the matrix-forming polymer is crosslinked, thereby forming a continuous polymer matrix as described above. The crosslinking solution preferably contains a solution of a polyvalent metal salt such as a solution of a metal chloride. Preferred polyvalent cations include calcium, iron, aluminum, manganese, copper, zinc or lanthanum. A particularly preferred salt is calcium chloride.

[0109] In a particular preferred embodiment of the present invention where the aerosol-generating solution contains an acid, the calcium salt provided in the crosslinking solution can advantageously be a salt of the same acid. For example, in an embodiment where the aerosol-generating solution contains lactic acid, the crosslinking solution can advantageously contain calcium lactate.

[0110] When the aerosol-generating solution contains nicotine, the acid in the aerosol-generating solution forms a nicotine salt together with nicotine. Therefore, the use of the calcium salt corresponding to the acid in the aerosol-generating solution provides the same salt as the salt in the aerosol-generating solution to the crosslinking solution. This then advantageously limits the diffusion of the nicotine salt from the aerosol-generating solution to the crosslinking solution during the crosslinking process. Therefore, a higher concentration of nicotine salt can be retained within the aerosol-generating element. Furthermore, the potential waste of nicotine and acid during the production of the aerosol-generating element can also be reduced.

[0111] The crosslinking solution preferably contains from about 0.5 weight percent to about 10 weight percent of the polyvalent metal salt in the crosslinking solution.

[0112] The crosslinking process is preferably carried out, for example, without heating at room temperature (22 degrees Celsius). The period during which the individual portions of the aerosol-generating solution are left in the crosslinking solution can be selected according to the degree of crosslinking desired in the aerosol-generating element. In a particular preferred embodiment, the individual portions of the aerosol-generating solution are left in the crosslinking solution for about 10 minutes to about 30 minutes.

[0113] The crosslinking solution preferably further contains the same polyhydric alcohol as the polyhydric alcohol selected as a component of the aerosol generating formulation. By including the polyhydric alcohol in the crosslinking solution, it has been found that during the crosslinking process, the diffusion of the polyhydric alcohol from the aerosol generating solution into the crosslinking solution is restricted. This advantageously enables the retention of a higher concentration of the polyhydric alcohol within the aerosol generating element than has been possible heretofore. Furthermore, the reduction in the diffusion of the polyhydric alcohol into the crosslinking solution can advantageously help to maintain the shape of the aerosol generating element during the crosslinking process.

[0114] The crosslinking solution preferably contains from about 20 weight percent to about 60 weight percent of the polyhydric alcohol, and more preferably contains from about 30 weight percent to about 50 weight percent of the polyhydric alcohol.

[0115] As described above, the polyhydric alcohol in the crosslinking solution is selected to be compatible with the polyhydric alcohol in the aerosol generating solution. In a preferred embodiment, the polyhydric alcohol is glycerin.

[0116] In a particularly preferred embodiment of the present invention, the concentration of the polyhydric alcohol in the crosslinking solution is adjusted according to the concentration of that polyhydric alcohol in the aerosol generating solution. In particular, it is desirable for the concentration of the polyhydric alcohol in the crosslinking solution to be as close as possible to the concentration of the same polyhydric alcohol in the aerosol generating solution. This has been found to optimize the beneficial effects of including the polyhydric alcohol in the crosslinking solution, as described above.

[0117] The concentration of the polyhydric alcohol in the crosslinking solution is preferably within about 20 percent of the concentration of the same polyhydric alcohol in the aerosol generating solution, more preferably within about 15 percent, and even more preferably within about 10 percent. In a particularly preferred embodiment, the concentration of the polyhydric alcohol in the crosslinking solution is substantially equal to the concentration of the same polyhydric alcohol in the aerosol generating solution.

[0118] After crosslinking, the resulting aerosol generating elements are removed from the crosslinking solution using, for example, a sieve or similar device. The aerosol generating elements are preferably rinsed to remove the crosslinking solution from the surface. The aerosol generating elements are then dried to reduce the water content to a desired level.

[0119] Drying of the aerosol generating elements is preferably carried out to reduce the water content of the aerosol generating elements to less than about 20 weight percent, more preferably less than about 15 weight percent. This level of water is preferred for the aerosol generating elements to generate aerosol in an efficient manner upon heating of the aerosol generating elements during use.

[0120] Preferably, drying of the aerosol generating elements is carried out to reduce the water activity (a w ) to less than about 0.7, more preferably less than about 0.5. This advantageously reduces the likelihood of bacterial and fungal growth in the aerosol generating elements.

[0121] The term "water activity" is used herein in connection with the present invention to denote the ratio of the partial vapor pressure of water at equilibrium of the aerosol generating element to the vapor saturation pressure of pure water at equilibrium at the same temperature. Thus, water activity is a dimensionless quantity between 0 corresponding to a completely anhydrous substance and 1 corresponding to salt-free pure water. The method for measuring the water activity of the aerosol generating elements according to the present invention is described in the 2017 publication of ISO 18787 (Foodstuffs - Determination of water activity). The dew point measurement principle described in ISO 18787 is preferably used.

[0122] The drying of the aerosol generating element can be carried out using any suitable means, including, for example, within a dryer in which the aerosol generating element is heated. The time and temperature of the drying process can be adjusted according to the apparatus used and to achieve the desired water level. For example, the aerosol generating element may be dried at 25 degrees Celsius for 12 hours or at 100 degrees Celsius for 3 hours. The drying may optionally be carried out under vacuum.

[0123] The method according to the invention may further comprise the step of coating the aerosol generating element to provide an outer coating layer on the aerosol generating element. The coating step may be carried out before or after the drying step. An optional drying step may be incorporated after the coating step.

[0124] The provision of a coating layer on the aerosol generating element may be desirable for many different reasons. For example, the coating layer may advantageously limit the permeation of oxygen or water vapor to the aerosol generating element, which may help to extend the shelf life of the aerosol generating element. Alternatively or additionally, the coating layer may serve to protect the structural integrity of the aerosol generating element or to provide improved smoothness of the aerosol generating element. In certain embodiments, a relatively fragile coating layer may be applied to an aerosol generating element that is adapted to be broken by the consumer prior to use. Thus, this type of coating layer can provide the consumer with a tactile and audible indication that the aerosol generating element has been activated. Alternatively or additionally, the provision of a coating layer on the aerosol generating element may be used, for example, to adjust the color of the aerosol generating element in order to provide a visual indication of the properties of the aerosol generating element, such as the flavor or nicotine content.

[0125] Suitable types of coating materials are known to those skilled in the art. For example, a coating layer of a water-soluble film former such as HPMC or shellac may be applied to the aerosol generating element. Such film formers can adhere strongly to the surface of the aerosol generating element. In a further embodiment, a coating layer of sodium alginate may be applied, which crosslinks with any residual calcium ions on the surface of the aerosol generating element to form a thin film of calcium alginate.

[0126] The coating layer may be applied to the outer surface of the aerosol generating element using various coating techniques. Suitable apparatus and techniques are known to those skilled in the art.

[0127] The method of the present invention has been described in relation to the production of a single aerosol generating element. However, it will be apparent to those skilled in the art that the present invention also encompasses methods for producing a plurality of aerosol generating elements. The methods described above can be readily adapted by those skilled in the art to produce a plurality of aerosol generating elements, for example, in a batch process where a plurality of individual portions of the aerosol generating solution are produced and added simultaneously to the crosslinking solution, or in a continuous process where individual portions of the aerosol generating solution are produced continuously and added to the crosslinking solution.

[0128] The method of the present invention produces an aerosol generating element having a distinct structure. As defined above, the aerosol generating element includes a continuous polymer matrix and an aerosol generating formulation dispersed within the continuous polymer matrix, and the aerosol generating formulation is trapped within the continuous polymer matrix.

[0129] Without wishing to be bound by theory, it is understood that in the aerosol generating element according to the present invention, the three-dimensional polymer matrix structure is formed by crosslinking and the aerosol generating formulation is retained within the continuous polymer matrix structure. This is in particular contrast to existing core / shell structures, where the contents of the core are released upon rupture of the shell.

[0130] Compounds that can be incorporated into the aerosol generating element and preferred amounts of these compounds have been described above in connection with the method of the present invention.

[0131] The aerosol generating formulation dispersed within the solid continuous matrix structure preferably occupies at least about 70 weight percent of the total weight of the aerosol generating element, or at least about 75 weight percent of the total weight of the aerosol generating element, or at least about 80 weight percent of the total weight of the aerosol generating element.

[0132] More preferably, the aerosol generating formulation dispersed within the solid continuous polymer matrix occupies at least about 82 weight percent of the total weight of the aerosol generating element. Even more preferably, the aerosol generating formulation dispersed within the continuous polymer matrix occupies at least about 84 weight percent of the total weight of the aerosol generating element.

[0133] In a particularly preferred embodiment, the aerosol generating formulation dispersed within the continuous polymer matrix occupies at least about 86 weight percent of the total weight of the aerosol generating element. More preferably, the aerosol generating formulation dispersed within the continuous polymer matrix occupies at least about 88 weight percent of the total weight of the aerosol generating element. Even more preferably, the aerosol generating formulation dispersed within the continuous polymer matrix occupies at least about 90 weight percent of the total weight of the aerosol generating element.

[0134] Most preferably, the aerosol generating formulation dispersed within the continuous polymer matrix occupies at least about 92 weight percent of the total weight of the aerosol generating element, or at least about 93 weight percent of the total weight of the aerosol generating element, or at least about 94 weight percent of the total weight of the aerosol generating element, or at least about 95 weight percent of the total weight of the aerosol generating element.

[0135] In an aerosol-generating element in which the aerosol-generating formulation occupies a fraction of the total weight of the aerosol-generating elements within the above range, advantageously, it is possible to minimize the portion of the heat supplied to the aerosol-generating element that is consumed to raise the temperature of the encapsulating material during use. Thus, more efficient use of the heat supplied to the aerosol-generating element is possible, such that most of the heat is effectively used for the release of the aerosol formulation components from the continuous polymer matrix and for aerosol generation.

[0136] As defined above, the aerosol-generating element according to the invention comprises a polyhydric alcohol as a constituent of the aerosol-generating formulation dispersed within a continuous polymer matrix. The aerosol-generating element according to the invention preferably comprises at least about 30 weight percent polyhydric alcohol, more preferably at least about 40 weight percent polyhydric alcohol, more preferably at least about 50 weight percent polyhydric alcohol, more preferably at least about 60 weight percent polyhydric alcohol, more preferably at least about 70 weight percent polyhydric alcohol, based on the total weight of the aerosol-generating element.

[0137] Typically, in the aerosol-generating element according to the invention, the polyhydric alcohol content in the aerosol-generating formulation occupies up to about 95 weight percent based on the total weight of the aerosol-generating element.

[0138] As defined above, in the aerosol generating element according to the present invention, the continuous polymer matrix is formed by a cross-linked matrix-forming polymer. The aerosol generating element preferably contains at least about 2 weight percent of the matrix-forming polymer, more preferably at least about 2.5 weight percent of the matrix-forming polymer, and even more preferably at least about 3 weight percent of the matrix-forming polymer. The aerosol generating element preferably contains less than about 6 weight percent of the matrix-forming polymer, more preferably less than about 5 weight percent of the matrix-forming polymer, and even more preferably less than about 4.5 weight percent of the matrix-forming polymer. For example, the aerosol generating element may contain from about 2 weight percent to about 6 weight percent of the matrix-forming polymer, or from about 2.5 weight percent to about 5 weight percent of the matrix-forming polymer, or from about 3 weight percent to about 4.5 weight percent of the matrix-forming polymer.

[0139] As defined above, in the aerosol generating element according to the present invention, the aerosol generating formulation dispersed within the continuous polymer matrix contains at least one alkaloid or cannabinoid compound. In some embodiments, the aerosol generating formulation dispersed within the continuous polymer matrix contains both an alkaloid compound and a cannabinoid compound.

[0140] Generally, the aerosol generating element may contain up to about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both. Considering the application of the aerosol generating element of the present invention as a substrate in an aerosol article, the content of the alkaloid compound, or the cannabinoid compound, or both in the element can be increased and adjusted from the perspective of optimizing the delivery of the alkaloid compound, or the cannabinoid compound, or both in aerosol form to the consumer, which is advantageous. Compared with existing aerosol generating substrates based on the use of plant materials, this may advantageously allow for a higher content of the alkaloid compound, or the cannabinoid compound, or both per volume or per weight of the substrate (element), which may be desirable from a manufacturing perspective.

[0141] The content of at least one alkaloid or cannabinoid compound in the aerosol generating formulation dispersed within the continuous polymer matrix preferably occupies at least 0.5 weight percent of the total weight of the aerosol generating element. Thus, the aerosol generating element preferably contains at least about 0.5 weight percent of an alkaloid compound, or at least 0.5 weight percent of a cannabinoid compound, or a combination of at least about 0.5 weight percent of an alkaloid compound and a cannabinoid compound.

[0142] More preferably, the aerosol generating element contains at least about 1 weight percent of an alkaloid compound, or a cannabinoid compound, or both. Even more preferably, the aerosol generating element contains at least about 2 weight percent of an alkaloid compound, or a cannabinoid compound, or both.

[0143] The aerosol generating element preferably contains less than about 8 weight percent of an alkaloid compound, or a cannabinoid compound, or both. The aerosol generating element more preferably contains less than about 6 weight percent of an alkaloid compound, or a cannabinoid compound, or both. The aerosol generating element still more preferably contains less than about 5 weight percent of an alkaloid compound, or a cannabinoid compound, or both. The aerosol generating element most preferably contains less than about 4 weight percent of an alkaloid compound, or a cannabinoid compound, or both.

[0144] In some embodiments, the aerosol generating element contains from about 0.5 weight percent to about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both, more preferably from about 1 weight percent to about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both, still more preferably from about 2 weight percent to about 10 weight percent of an alkaloid compound, or a cannabinoid compound, or both.

[0145] As described above in connection with the method of the present invention, in some preferred embodiments, the aerosol generating element contains nicotine.

[0146] Generally, the aerosol generating element can contain up to about 10 weight percent nicotine. This is advantageous because, considering the application of the aerosol generating element of the present invention as a substrate in an aerosol article, the nicotine content in the aerosol generating element can be increased and adjusted from the perspective of optimizing the delivery of nicotine to the consumer in aerosol form. Compared to existing aerosol generating substrates based on the use of tobacco plants, this advantageously allows for a higher content of nicotine per volume or per weight of the substrate (element), which may be desirable from a manufacturing perspective.

[0147] The aerosol generating element preferably contains at least about 0.5 weight percent nicotine. More preferably, the aerosol generating element contains at least about 1 weight percent nicotine. Even more preferably, the aerosol generating element contains at least about 2 weight percent nicotine.

[0148] The aerosol generating element preferably contains up to about 8 weight percent nicotine. More preferably, the aerosol generating element contains a nicotine content of up to about 6 weight percent. Even more preferably, the aerosol generating element contains up to about 5 weight percent nicotine. Most preferably, the aerosol generating element contains up to about 4 weight percent nicotine.

[0149] In some embodiments, the aerosol generating element contains from about 0.5 weight percent to about 10 weight percent nicotine, more preferably from about 1 weight percent to about 10 weight percent nicotine, and even more preferably from about 2 weight percent to about 10 weight percent nicotine.

[0150] The aerosol generating element preferably contains at least about 0.5 milligrams of nicotine. More preferably, the aerosol generating element contains at least about 1 milligram of nicotine. Even more preferably, the aerosol generating element contains at least about 1.5 milligrams of nicotine. In particularly preferred embodiments, the aerosol generating element contains at least about 2 milligrams of nicotine, most preferably at least about 2.5 milligrams of nicotine.

[0151] The aerosol generating element can contain up to about 6 milligrams of nicotine. The aerosol generating element preferably contains up to about 5 milligrams of nicotine. More preferably, the aerosol generating element contains up to about 4.5 milligrams of nicotine. Even more preferably, the aerosol generating element contains up to about 4 milligrams of nicotine. In particularly preferred embodiments, the aerosol generating element contains up to about 3.5 milligrams of nicotine, most preferably up to about 3 milligrams of nicotine.

[0152] In some preferred embodiments, the aerosol generating formulation dispersed within the continuous polymeric matrix of the aerosol generating element comprises a cannabinoid compound. The cannabinoid compound is preferably selected from CBD and THC. More preferably, the cannabinoid compound is CBD.

[0153] The aerosol generating element may contain up to about 10 weight percent of CBD. Preferably, the aerosol generating element contains at least about 0.5 weight percent of CBD. More preferably, the aerosol generating element contains at least about 1 weight percent of CBD. Even more preferably, the aerosol generating element contains at least about 2 weight percent of CBD.

[0154] Preferably, the aerosol generating element contains up to about 6 weight percent of CBD. More preferably, the aerosol generating element contains up to about 5 weight percent of CBD. Even more preferably, the aerosol generating element contains up to about 4 weight percent of CBD.

[0155] In some embodiments, the aerosol generating element contains from about 0.5 weight percent to about 10 weight percent of CBD, more preferably from about 1 weight percent to about 10 weight percent of CBD, and even more preferably from about 2 weight percent to about 10 weight percent of CBD.

[0156] The aerosol generating element according to the present invention can be an aerosol generating element that is substantially tobacco-free.

[0157] As used herein in connection with the present invention, the term "substantially tobacco-free aerosol generating element" describes an aerosol generating element having a tobacco content of less than 1 weight percent. For example, the aerosol generating element can have a tobacco content of less than about 0.75 weight percent, less than about 0.5 weight percent, or less than about 0.25 weight percent.

[0158] The aerosol generating element may be a tobacco-free aerosol generating element.

[0159] As used herein in connection with the present invention, the term "tobacco-free aerosol generating element" describes an aerosol generating element having a tobacco content of 0 weight percent.

[0160] As described above, in some embodiments, the aerosol generating formulation dispersed within the continuous polymeric matrix further comprises an acid.

[0161] The aerosol generating element may contain up to about 10 weight percent acid.

[0162] Preferably, the aerosol generating element contains at least about 0.5 weight percent acid. More preferably, the aerosol generating element contains at least about 1 weight percent acid. Even more preferably, the aerosol generating element contains at least about 2 weight percent acid.

[0163] Preferably, the aerosol generating element contains up to about 8 weight percent acid. More preferably, the aerosol generating element contains up to about 6 weight percent acid. Even more preferably, the aerosol generating element contains up to about 5 weight percent acid. Most preferably, the aerosol generating element contains up to about 4 weight percent acid.

[0164] In some embodiments, the aerosol generating element contains from about 0.5 weight percent to about 10 weight percent acid, more preferably from about 1 weight percent to about 10 weight percent acid, even more preferably from about 2 weight percent to about 10 weight percent acid.

[0165] Preferably, the aerosol generating element according to the present invention contains up to about 25 weight percent water.

[0166] The aerosol generating element preferably contains 20 weight percent or less of water. More preferably, the aerosol generating element contains 15 percent or less of water.

[0167] The aerosol generating element according to the present invention preferably contains at least about 2.5 weight percent of water. More preferably, the aerosol generating element according to the present invention contains at least about 5 weight percent of water. Even more preferably, the aerosol generating element according to the present invention contains at least about 7.5 weight percent of water. Most preferably, the aerosol generating element according to the present invention preferably contains at least about 10 weight percent of water.

[0168] Generally, the presence of some water has been observed to contribute to providing desirable stability to the aerosol generating element. At the same time, a residual water content of 25 weight percent or less is desirable because an aerosol generating element that is not substantially sticky can be obtained. Further, when heating an aerosol generating element with a low water content, an aerosol more concentrated in a polyhydric alcohol and an alkaloid or cannabinoid compound such as nicotine can be provided to the consumer.

[0169] The aerosol generating element according to the present invention may have an equivalent diameter of at least about 0.5 millimeters.

[0170] The term "equivalent diameter of the aerosol generating element" is used herein to mean the diameter of a sphere having the same volume as the aerosol generating element. Generally, the aerosol generating element preferably has a spherical or quasi-spherical shape such as an egg shape or an elliptical shape, but can have any shape. For an aerosol generating element having a spherical shape and a circular cross-section, the equivalent diameter is the diameter of the cross-section of the aerosol generating element.

[0171] The aerosol generating element preferably has an equivalent diameter of at least about 1 millimeter. More preferably, the aerosol generating element has an equivalent diameter of at least about 2 millimeters. Even more preferably, the aerosol generating element has an equivalent diameter of at least about 3 millimeters.

[0172] The aerosol generating element according to the present invention preferably has an equivalent diameter of about 8 millimeters or less. More preferably, the aerosol generating element has an equivalent diameter of about 6 millimeters or less. Even more preferably, the aerosol generating element has an equivalent diameter of about 5 millimeters or less.

[0173] In some embodiments, the aerosol generating element has an equivalent diameter of from about 0.5 millimeter to about 8 millimeters, preferably from about 1 millimeter to about 8 millimeters, more preferably from about 2 millimeters to about 8 millimeters, and even more preferably from about 3 millimeters to 8 millimeters.

[0174] In a particularly preferred embodiment, the aerosol generating element has an equivalent diameter of about 4 millimeters or about 4.5 millimeters.

[0175] The aerosol generating element according to the present invention may have an ellipticity of up to about 35 percent.

[0176] As used herein in connection with the present invention, the term "ellipticity" indicates the degree of deviation from a perfect circle. Ellipticity is expressed as a percentage and is defined mathematically as follows.

Equation

[0177] To determine the ellipticity of an object such as an aerosol generating element, the object can be viewed along a direction that is substantially perpendicular to the cross-section of the aerosol generating element. As an example, the aerosol generating element may be positioned on a transparent stage such that an image of the aerosol generating element is recorded by a suitable imaging device located below the stage. Dimension "a" is taken as the maximum outer diameter of the image of the aerosol generating element, and dimension "b" is taken as the minimum outer diameter of the image of the aerosol generating element. The process is repeated for a total of 10 aerosol generating elements that have the same composition and are prepared under the same operating conditions by the same process. The number average of the 10 ellipticity measurements is recorded as the ellipticity of that aerosol generating element.

[0178] The aerosol generating element according to the present invention preferably has an ellipticity of about 30 percent or less. The aerosol generating element according to the present invention more preferably has an ellipticity of about 25 percent or less. The aerosol generating element according to the present invention still more preferably has an ellipticity of about 20 percent or less.

[0179] The aerosol generating element according to the present invention typically has an ellipticity of at least about 1 percent. The aerosol generating element preferably has an ellipticity of at least 2 percent. The aerosol generating element more preferably has an ellipticity of at least 3 percent. The aerosol generating element still more preferably has an ellipticity of at least 4 percent.

[0180] In some embodiments, the aerosol generating element has an ellipticity of from about 1 percent to about 30 percent, more preferably from about 2 percent to about 30 percent, more preferably from about 3 percent to about 30 percent, still more preferably from about 4 percent to about 30 percent.

[0181] The aerosol generating article according to the present invention can have a maximum exposed surface area to volume ratio of 25 cm -1 of.

[0182] As used herein with reference to the present invention, the expression "exposed surface area to volume ratio" refers to the ratio of the total outer surface area of the aerosol generating element that is exposed and available for heat and mass transfer to the total volume of the aerosol generating element.

[0183] The aerosol generating element according to the present invention has a low ellipticity and can be assimilated to a spherical object, so the volume of the aerosol generating element according to the present invention can be represented by the following formula.

Number

[0184] The exposed surface area of the aerosol generating element according to the present invention can be estimated by the following formula.

Number

[0185] Dimension R eq represents the equivalent radius of the aerosol generating element.

[0186] The aerosol generating article preferably has an exposed surface area to volume ratio of at least about 0.083 cm -1 . The aerosol generating article more preferably has an exposed surface area to volume ratio of at least about 0.166 cm -1 . The aerosol generating article even more preferably has an exposed surface area to volume ratio of at least about 0.249 cm -1 .

[0187] The aerosol generating article preferably has an exposed surface area to volume ratio of about 24 cm -1 or less. The aerosol generating article more preferably has an exposed surface area to volume ratio of about 20 cm -1 or less. The aerosol generating article even more preferably has an exposed surface area to volume ratio of about 16 cm -1 or less.

[0188] In some embodiments, the aerosol generating article is about 0.083 cm-1 ~about 24 cm -1 、more preferably, about 0.166 cm -1 ~about 24 cm -1 、even more preferably, about 0.249 cm -1 ~about 24 cm -1 and has an exposed surface area to volume ratio of

[0189] In some embodiments, as described above in connection with the methods of the present invention, the aerosol generating element according to the present invention may be coated.

[0190] The aerosol generating element as described above may find use as an aerosol generating substrate for an aerosol generating article of the type in which the substrate is heated to emit an inhalable aerosol, as opposed to an article in which the substrate is burned to produce smoke.

[0191] The aerosol generating element according to the present invention is easy to manufacture and is well-defined, and thus an individual amount of the aerosol generating formulation may be provided in encapsulated form. In particular, with respect to the content of polyhydric alcohols and alkaloid or cannabinoid compounds, the composition of the aerosol generating formulation can be finely adjusted and controlled. Therefore, the aerosol generating element according to the present invention is versatile and can be used as a substrate in numerous arrangements.

[0192] As an example, a plurality of aerosol generating elements according to the present invention may be provided within a cavity defined by a tubular element, such that the outer surface of the aerosol generating element is exposed inside the longitudinally extending airflow channel defined by the cavity. Upon heating, an aerosol can be generated from the aerosol generating element, and thus the aerosol can be released into the airflow channel and drawn through the tubular element into the consumer's mouth.

[0193] Accordingly, an aerosol generating element as described above may find use in an aerosol generating system comprising one or more aerosol generating elements or articles as described above, and an electrically operated aerosol generating device. A suitable aerosol generating device comprises a heating element and a heating chamber configured to receive one or more aerosol generating elements or articles such that the one or more aerosol generating elements are heated within the heating chamber by the heating element.

[0194] Upon heating, the aerosol generating element according to the present invention releases an aerosol containing aerosol generating formulation components, in particular polyhydric alcohols and alkaloids or cannabinoid compounds. When the aerosol generating element according to the present invention is heated to a temperature in the range of about 150°C to about 350°C, it has been found that the aerosol generating element loses weight without significant volume contraction. Further, when the aerosol generating element according to the present invention is heated to a temperature in the range of about 150°C to about 350°C and heat is supplied until no further weight loss is detected, the residual weight of the aerosol generating element is typically less than 120 weight percent of the continuous polymer matrix component, preferably less than 115 weight percent of the components of the continuous polymer matrix, more preferably less than 115 weight percent of the components of the continuous polymer matrix, and still more preferably less than 105 weight percent of the continuous polymer matrix component.

[0195] Most preferably, when the aerosol generating element according to the present invention is heated to a temperature in the range of about 150°C to about 350°C and heat is supplied until no further weight loss is detected, the residual weight of the aerosol generating element substantially corresponds to the total weight of the components of the continuous polymer matrix.

[0196] One embodiment of the present invention will now be further described by way of example only.

Example

[0197] An aerosol generating solution is formed from a mixture of the following components. [Table 1]

[0198] In the first step, sodium alginate is added to water to form a matrix polymer solution. Then nicotine is added, followed by glycerin, and finally levulinic acid is added.

[0199] The resulting aerosol generating solution is extruded through a 5 millimeter nozzle to form a plurality of droplets, which are then dropped from a height of 30 centimeters at room temperature into a crosslinking solution having the following composition: [Table 2]

[0200] The droplets are left in the crosslinking solution for 25 minutes before removal and dried in a tray dryer at 25 degrees Celsius for 12 hours. The resulting dried aerosol generating element is in the form of solid spherical beads having a diameter of about 4.6 mm. Each bead has a weight of approximately 65 mg, a water activity of 0.4, and has the following composition: [Table 3]

Claims

1. A method for generating an aerosol generating element for an aerosol generating article or system, the method comprising: preparing a matrix polymer solution containing a matrix-forming polymer in water; adding a plurality of aerosol generating formulation components to the matrix polymer solution to form an aerosol generating solution, the aerosol generating formulation components including a polyhydric alcohol and at least one alkaloid or cannabinoid, and the aerosol generating solution containing at least 0.5 weight percent of the at least one alkaloid or cannabinoid, the adding step; forming individual portions of the aerosol generating solution; adding the individual portions of the aerosol generating solution to a crosslinking solution of polyvalent cations to crosslink the matrix-forming polymer; removing the aerosol generating element from the crosslinking solution and drying the aerosol generating element.

2. The method according to claim 1, wherein the aerosol generating formulation components further include an acid.

3. The method according to claim 1 or 2, wherein the step of forming individual portions of the aerosol generating solution includes forming droplets of the aerosol generating solution, and the droplets are dropped into the crosslinking solution from a height of at least 10 cm.

4. The method according to any one of claims 1 to 3, wherein the viscosity of the aerosol generating solution is less than 5000 mPa·s.

5. The method according to any one of claims 1 to 4, wherein the aerosol generating formulation components are sequentially added to the matrix polymer solution.

6. The method according to any one of claims 1 to 5, wherein the aerosol generating solution contains at least 20 weight percent of the polyhydric alcohol.

7. The method according to any one of claims 1 to 6, wherein the polyhydric alcohol is glycerin, propylene glycol, or a combination of glycerin and propylene glycol.

8. The method according to any one of claims 1 to 7, wherein the aerosol generating solution contains at least 0.5% by weight of nicotine.

9. The method according to any one of claims 1 to 8, wherein the matrix-forming polymer contains alginate and the matrix polymer solution contains at least 45% by weight of water.

10. The method according to any one of claims 1 to 9, wherein the crosslinking solution contains at least 20% by weight of a polyhydric alcohol, and the polyhydric alcohol in the crosslinking solution is the same as the polyhydric alcohol in the aerosol generating solution.

11. The method according to claim 10, wherein the concentration of the polyhydric alcohol in the crosslinking solution is within 20% of the concentration of the polyhydric alcohol in the aerosol generating solution.

12. The method according to any one of claims 1 to 11, wherein during the drying step, the water content of the aerosol generating element is reduced to less than 20% by weight.

13. The method according to any one of claims 1 to 12, wherein after drying, the aerosol generating element has a polyhydric alcohol content of at least 60% by weight.

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