Aerosol-generating article having a novel aerosol-generating substrate

Abstract

The aerosol-generating article (10) includes an aerosol-generating substrate comprising a porous medium loaded with a heterogeneous aerosol-generating suspension of an inert powder in a liquid vehicle, the liquid vehicle including one or more aerosol formers, and a [liquid] nicotine source, the aerosol-generating suspension including at least 20 percent by weight of the inert powder and at least 30 percent by weight of the one or more aerosol formers.

Description

[Technical field]

[0001] The present invention relates to an aerosol-generating substrate for an aerosol-generating article, to an aerosol-generating article comprising such an aerosol-generating substrate, and to a method of producing such an aerosol-generating substrate. [Background technology]

[0002] Aerosol-generating articles in which an aerosol-generating substrate, such as a nicotine- or tobacco-containing substrate, is heated rather than combusted, 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 located in contact with, within, around, 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 are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

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

[0004] Substrates for heated aerosol generating articles have often been produced using randomly oriented pieces, strands, or strips of tobacco material. Alternatively, rods for heated aerosol generating articles formed from an assembly of sheets of tobacco material are disclosed, by way of 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 may be formed by casting, rolling, calendering or extrusion of 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 WO-A-2011 / 101164 may be formed from strands of homogenized tobacco material obtained by extruding a mixture comprising particulate tobacco and at least one aerosol former to form a continuous length of homogenized tobacco material.

[0006] Homogenized tobacco material is typically heated to a relatively high temperature during use, for example, about 350 degrees Celsius, to optimize aerosol generation and nicotine release from the tobacco. For this reason, aerosol-generating articles containing homogenized tobacco material are commonly heated in an aerosol generating device that includes an internal heating element that is inserted into the homogenized tobacco rod to provide internal heating.

[0007] Alternative forms of nicotine-containing substrates have also been disclosed. As an example, liquid nicotine compositions, often referred to as e-liquids, have been proposed. These liquid compositions may be heated, for example, by a coiled, electrically resistive filament of the aerosol generating device. This type of substrate may require particular care in the manufacture of the container holding the liquid composition to prevent undesired leakage. To address this issue and simplify the overall manufacturing process, it has also been proposed to provide a gel composition containing nicotine that generates a nicotine-containing aerosol upon heating. As an example, International Patent Application No. WO-A-2018 / 019543 discloses a thermoreversible gel composition, i.e. a gel that becomes fluid when heated to a melting temperature and that again fixes into a gel at a gelling temperature. The gel is provided within a housing of a cartridge, which may be discarded and replaced when the gel is consumed.

[0008] Such gel compositions may not be suitable for use in directly forming aerosol-generating substrate rods for aerosol-generating articles because it is difficult to retain the gel within the aerosol-generating substrate rod, thereby posing problems of leakage of the gel outside the article.

[0009] It would be desirable to provide novel aerosol-generating substrates for aerosol-generating articles that can provide more effective release of aerosol and nicotine at lower temperatures, such as those provided by aerosol-generating devices incorporating external or inductive heating means. It would be particularly desirable if such aerosol-generating substrates could provide optimized delivery of nicotine while minimizing levels of undesirable compounds. It would further be desirable to provide such aerosol-generating substrates that reduce or preferably substantially eliminate the leakage problems experienced with liquid and gel substrates. It would further be desirable to provide such aerosol-generating substrates that can be easily and efficiently manufactured and incorporated into existing aerosol-generating articles without significant modifications to the article structure and assembly method. Summary of the Invention

[0010] The present invention relates to an aerosol-generating substrate for an aerosol-generating article, the aerosol-generating substrate comprising a porous medium loaded with a heterogeneous aerosol-generating suspension. The aerosol-generating suspension may comprise an inert powder in a liquid vehicle. The liquid vehicle may comprise one or more aerosol formers and a nicotine source. The aerosol-generating suspension may comprise at least 20 percent by weight of the inert powder. The aerosol-generating suspension may comprise at least 30 percent by weight of one or more aerosol formers.

[0011] According to a first aspect of the present invention there is provided an aerosol-generating substrate for an aerosol-generating article, the aerosol-generating substrate comprising a porous medium filled with a heterogeneous aerosol-generating suspension of an inert powder in a liquid solvent, the liquid solvent comprising one or more aerosol formers and a nicotine source, the aerosol-generating suspension comprising at least 20 percent by weight of the inert powder and at least 30 percent by weight of the one or more aerosol formers.

[0012] According to a second aspect of the present invention there is provided an aerosol-generating article comprising a rod formed of an aerosol-generating substrate, the aerosol-generating substrate comprising a porous medium filled with a heterogeneous aerosol-generating suspension of an inert powder in a liquid solvent, the liquid solvent comprising one or more aerosol formers and a nicotine source, the aerosol-generating suspension comprising at least 20 percent by weight of the inert powder and at least 30 percent by weight of the one or more aerosol formers.

[0013] According to a third aspect of the present invention there is provided a method of producing an aerosol-generating substrate, the method comprising the steps of providing a liquid solvent comprising one or more aerosol formers, a nicotine source and optionally water, providing an inactive powder, mixing the plant powder with the liquid solvent to form a heterogeneous suspension of the inactive powder in the liquid solvent, and depositing the heterogeneous suspension onto a porous medium to form an aerosol-generating suspension.

[0014] According to the present invention there is provided an aerosol-generating article comprising an aerosol-generating substrate, the aerosol-generating substrate comprising a porous medium loaded with an aerosol-generating suspension of an inert powder in a liquid solvent, the liquid solvent comprising one or more aerosol formers and a nicotine source, the aerosol-generating suspension comprising at least 20 percent by weight of the inert powder and at least 30 percent by weight of the one or more aerosol formers.

[0015] References herein to features of an aerosol-generating article or aerosol-generating substrate according to the invention are assumed to apply to all aspects of the invention, unless otherwise stated.

[0016] As used herein, the term "aerosol-generating article" refers to a heated aerosol-generating article for the production of aerosol that includes an aerosol-generating substrate that is intended to be heated, rather than combusted, to release volatile compounds capable of forming an aerosol. Such articles are commonly referred to as non-combustion heated products.

[0017] The term "aerosol-generating substrate" as used herein means a substrate capable of releasing, upon heating, volatile compounds capable of forming an aerosol. The aerosol generated from the aerosol-generating substrate of the aerosol-generating articles described herein may be visible or invisible and may include vapor (e.g., fine particles of a substance in a gaseous state, e.g., of a substance that is normally liquid or solid at room temperature) and liquid droplets of gas and condensed vapor.

[0018] As used herein, the term "aerosol-generating suspension" refers to a suspension that has the ability to release volatile compounds upon heating that can form an aerosol. The aerosol-generating suspension of the present invention is a heterogeneous mixture of particles of an inert powder suspended in a liquid solvent. The inert powder is not dissolved in the liquid solvent but is distributed throughout it. In the context of the present invention, the aerosol-generating suspension is defined as non-colloidal. In particular, the aerosol-generating suspension is not a gel and does not contain a gelling agent. As used herein, the term "gelling agent" refers to a thickening agent that increases the viscosity of the aerosol-generating suspension through the formation of a colloidal gel. Common gelling agents include gums, pectin, agar, and gelatin.

[0019] As used herein, the term "inert" refers to a material that is sensorily inert in that it has negligible or zero contribution to the flavor or odor of the aerosol generated from the aerosol-generating suspension. Thus, the inclusion of the inert powder does not affect the sensory properties of the aerosol generated upon heating of the aerosol-generating substrate. In particular, the inert powder is flavorless and does not contain volatile flavor compounds that would be released in the aerosol upon heating of the aerosol-generating substrate at temperatures up to 350 degrees Celsius. In the context of the present invention, the inert powder is intended to add viscosity to the suspension but not affect the composition or properties of the aerosol generated from the liquid solvent upon heating. The inert powder is preferably a non-tobacco material.

[0020] As used herein, the term "porous medium" refers to any suitable porous carrier material having a plurality of pores and providing a structure capable of retaining an aerosol-generating suspension within its pores. The porous medium must be capable of being incorporated into a rod of an aerosol-generating substrate for an aerosol-generating article. The porous medium is inert, in particular sensorially inert, and does not contribute to the aerosol formed upon heating of the aerosol-generating substrate.

[0021] As used herein, the term "loaded" is used to describe the retention of the aerosol-generating suspension within the porous medium. In other words, the porous medium is "filled" with the aerosol-generating suspension and effectively retains or carries it within the aerosol-generating substrate. Thus, the porous medium acts as a porous carrier to contain and retain the aerosol-generating suspension within the aerosol-generating substrate. As discussed above, the aerosol-generating suspension may be dispersed within the porous structure of the porous medium and effectively retained within its pores.

[0022] As discussed above, the present invention provides a novel aerosol-generating substrate having a non-uniform aerosol-generating suspension loaded onto a porous medium. The aerosol-generating suspension provides an inert powder suspended in a liquid vehicle that includes one or more aerosol formers and a nicotine source. This provides a new method of combining nicotine and the aerosol formers within the aerosol-generating substrate.

[0023] The use of the defined aerosol-generating suspension has been found to optimise aerosol generation and nicotine release when the aerosol-generating substrate is heated at relatively low temperatures, for example at temperatures below about 275 degrees Celsius. This advantageously allows the aerosol-generating substrate to be used in an aerosol-generating article which is intended to be heated by an aerosol-generating device having external heating means, which externally heats a rod of the aerosol-generating substrate, typically heating the aerosol-generating substrate to a temperature of about 230-270 degrees Celsius. The aerosol-generating substrate may also be suitable for heating by induction means, where the substrate is typically heated to a relatively low temperature.

[0024] Surprisingly, it has been found that when nicotine and aerosol former are provided in the form of suspension, as defined, a lower temperature is required to aerosolize volatile compounds from aerosol-generating substrate, compared to aerosol-generating substrate in sheet form, such as cast leaf.The use of lower temperature is particularly advantageous, since the level of certain undesirable aerosol compounds is typically reduced.Overall, the ratio of desirable and undesirable compounds in aerosol can be increased.This optimizes the overall experience provided to consumers when used.

[0025] It has been found that aerosol-generating substrate forms having an aerosol-generating suspension supported on a porous medium effectively retain the aerosol-generating suspension in place within the aerosol-generating substrate. Thus, leakage of the aerosol-generating suspension from the aerosol-generating substrate is minimized or substantially prevented. Migration of the aerosol-generating suspension within the aerosol-generating article is also substantially prevented. Thus, the use of an aerosol-generating substrate in the form of a suspension offers significant advantages over the use of liquid or gel substrates.

[0026] The aerosol-generating substrate of the present invention can be produced by a relatively simple production method that does not require complex processing steps such as gelation. The aerosol-generating suspension is typically relatively viscous so that it can be easily deposited on the porous medium, as described below. The relatively high viscosity of the aerosol-generating suspension further improves the retention of the aerosol-generating suspension in the porous medium, as described above.

[0027] The combination of the porous medium and the aerosol-generating suspension supported thereon can be readily formed into a rod of aerosol-generating substrate, which can be combined with other components to form an aerosol-generating article having a similar structure to existing aerosol-generating articles. This means that the aerosol-generating substrate of the present invention can be advantageously incorporated into an aerosol-generating article without the need to significantly modify the process or apparatus for assembling the aerosol-generating article.

[0028] As defined above, the aerosol-generating substrate of the present invention is in the form of an aerosol-generating suspension dispersed within a porous medium. The aerosol-generating suspension is a suspension of an inert powder in a liquid vehicle, the liquid vehicle comprising one or more aerosol formers, nicotine, and optionally one or more of water, acid and flavourings, as discussed in more detail below.

[0029] As mentioned above, the aerosol-generating suspension includes an inert powder that acts as a thickening or viscosifying agent to increase the viscosity of the suspension so that it has the desired consistency for application to the porous medium and for retention in the porous medium during storage. The inert powder does not contribute to the properties of the aerosol generated from the aerosol-generating substrate and therefore does not affect the sensory properties of the aerosol, such as taste or odor.

[0030] The inert powder may be formed of any flavor compound-infused plant material. For example, the inert powder may be an inert cellulose powder, such as cellulose powder, carboxymethyl cellulose (CMC), microcrystalline cellulose (MCC), or a combination thereof.

[0031] Alternatively, and preferably, the inert powder is formed from non-vegetable materials.

[0032] In certain preferred embodiments, the inert powder is formed of one or more inorganic compounds. Suitable inorganic compounds include, but are not limited to, silicon dioxide, calcium carbonate, zeolites, alumina, clays, or combinations thereof.

[0033] In another preferred embodiment, the inert powder is formed of one or more polysaccharides. Suitable polysaccharides include, but are not limited to, tapioca (manioc), guar gum, xanthan gum, starch, and combinations thereof.

[0034] According to the present invention, the aerosol-generating suspension comprises at least about 20 weight percent of the inert powder, more preferably at least about 25 weight percent of the inert powder, and more preferably at least about 30 weight percent of the inert powder, based on the total weight (including water) of the aerosol-generating suspension.

[0035] More preferably, the aerosol-generating suspension comprises up to about 50 percent by weight of the inert powder, and more preferably up to about 45 percent by weight of the inert powder, based on the total weight of the aerosol-generating suspension.

[0036] For example, the aerosol-generating suspension may contain from about 20 weight percent to about 50 weight percent of the inert powder, or from about 25 weight percent to about 50 weight percent of the inert powder, or from about 30 weight percent to about 50 weight percent of the inert powder, or from about 20 weight percent to about 45 weight percent of the inert powder, or from about 25 weight percent to about 45 weight percent of the inert powder, or from about 30 weight percent to about 45 weight percent of the inert powder, based on the total weight of the aerosol-generating suspension.

[0037] Providing an inert powder within this weight range ensures that the aerosol-generating suspension is viscous enough to be successfully applied to and retained in the porous media.

[0038] Preferably, the aerosol-generating substrate comprises at least about 8 percent by weight of the inert powder, more preferably at least about 15 percent by weight of the inert powder, and most preferably at least about 20 percent by weight of the inert powder, based on the total weight of the aerosol-generating substrate including the aerosol-generating suspension and the porous medium.

[0039] Preferably, the aerosol-generating substrate comprises up to about 40 percent by weight of the inert powder, more preferably up to about 35 percent by weight of the inert powder, and even more preferably up to about 30 percent by weight of the inert powder, based on the total weight of the aerosol-generating substrate including the aerosol-generating suspension and the porous medium.

[0040] For example, the aerosol-generating substrate may contain from about 8 weight percent to about 40 weight percent of the inert powder, or from about 15 weight percent to about 35 weight percent of the inert powder, or from about 20 weight percent to about 30 weight percent of the inert powder, based on the total weight of the aerosol-generating substrate.

[0041] Aerosol-generating articles according to the present invention preferably comprise at least about 25 milligrams of inert powder per rod of aerosol-generating substrate, more preferably at least about 40 milligrams of inert powder per rod of aerosol-generating substrate, and even more preferably at least about 60 milligrams of inert powder per rod of aerosol-generating substrate.

[0042] Aerosol-generating articles according to the present invention preferably contain up to about 125 milligrams of inert powder per rod of aerosol-generating substrate, more preferably up to about 100 milligrams of inert powder per rod of aerosol-generating substrate, and even more preferably up to about 80 milligrams of inert powder per rod of aerosol-generating substrate.

[0043] For example, the inert powder preferably has an average particle size of about 20 microns to about 300 microns, more preferably about 50 microns to about 250 microns, and even more preferably about 100 microns to about 200 microns.

[0044] As mentioned above, the inert powder is suspended in a liquid medium, preferably an aqueous liquid medium. The liquid medium includes one or more aerosol formers. Upon volatilization, the aerosol formers can carry other vaporized compounds that are released from the aerosol-generating substrate upon heating, such as nicotine and flavorants in the aerosol. The aerosolization of a particular compound from an aerosol-generating substrate is not determined solely by its boiling point. The amount of the compound that is aerosolized can be influenced by the physical form of the substrate, as well as by other components that are also present in the substrate. The stability of the compound under the temperature and time frame of aerosolization also affects the amount of the compound present in the aerosol.

[0045] Aerosol formers suitable for inclusion in the liquid vehicle are known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol mono-, di-, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). The liquid vehicle can contain a single aerosol former or a combination of two or more aerosol formers.

[0046] In a preferred embodiment of the invention, the aerosol-generating suspension comprises a liquid solvent that includes glycerol, alone or in combination with propylene glycol.

[0047] As defined above, the aerosol-generating suspension of the aerosol-generating substrate according to the present invention comprises at least about 30 percent by weight of one or more aerosol formers, based on the total weight of the aerosol-generating suspension (including water, if present). The aerosol-generating suspension preferably comprises at least about 35 percent by weight of one or more aerosol formers, more preferably at least about 40 percent by weight of one or more aerosol formers, more preferably at least about 45 percent by weight of one or more aerosol formers, more preferably at least about 50 percent by weight of one or more aerosol formers.

[0048] The aerosol-generating suspension preferably contains up to about 90 percent by weight of the one or more aerosol formers, more preferably up to about 85 percent by weight of the one or more aerosol formers, more preferably up to about 80 percent by weight of the one or more aerosol formers, more preferably up to about 75 percent by weight of the one or more aerosol formers, and more preferably up to about 70 percent by weight of the one or more aerosol formers.

[0049] For example, the aerosol-generating suspension can contain from about 30 percent to about 90 percent by weight of one or more aerosol formers, or from about 35 percent to about 85 percent by weight of one or more aerosol formers, or from about 40 percent to about 80 percent by weight of one or more aerosol formers, or from about 45 percent to about 75 percent by weight of one or more aerosol formers, or from about 50 percent to about 70 percent by weight of one or more aerosol formers.

[0050] The level of aerosol former in the aerosol-generating suspension and the ratio of inert powder to aerosol former can be adjusted to provide a desired viscosity for the aerosol-generating suspension.

[0051] Preferably, the aerosol-generating substrate comprises at least about 25 percent by weight of the one or more aerosol formers, more preferably at least about 30 percent by weight of the one or more aerosol formers, and most preferably at least about 40 percent by weight of the one or more aerosol formers, based on the total weight of the aerosol-generating substrate including the aerosol-generating suspension and the porous medium.

[0052] The aerosol-generating substrate preferably comprises up to about 75 percent by weight of the one or more aerosol formers, more preferably up to about 70 percent by weight of the one or more aerosol formers, and even more preferably up to about 60 percent by weight of the one or more aerosol formers, based on the total weight of the aerosol-generating substrate including the aerosol-generating suspension and the porous medium.

[0053] For example, the aerosol-generating substrate may contain from about 25 percent to about 75 percent by weight of one or more aerosol formers, or from about 30 percent to about 70 percent by weight of one or more aerosol formers, or from about 40 percent to about 60 percent by weight of one or more aerosol formers, based on the total weight of the aerosol-generating substrate.

[0054] Aerosol-generating articles according to the present invention preferably comprise at least about 75 milligrams of one or more aerosol formers per rod of aerosol-generating substrate, more preferably at least about 100 milligrams of one or more aerosol formers per rod of aerosol-generating substrate, and even more preferably at least about 125 milligrams of one or more aerosol formers per rod of aerosol-generating substrate.

[0055] Aerosol-generating articles according to the present invention preferably contain up to about 225 milligrams of one or more aerosol formers per rod of aerosol-generating substrate, more preferably up to about 200 milligrams of one or more aerosol formers per rod of aerosol-generating substrate, and even more preferably up to about 175 milligrams of one or more aerosol formers per rod of aerosol-generating substrate.

[0056] The liquid vehicle additionally comprises a nicotine source, which is preferably a liquid nicotine source.

[0057] In certain embodiments, the nicotine source may be in the form of a liquid tobacco extract obtained from tobacco material during an extraction process in which the tobacco material is heated to release volatile compounds.

[0058] In other embodiments, the nicotine source may be in the form of liquid nicotine, which is a solution of nicotine in an aerosol former such as glycerol or propylene glycol, in which case any aerosol former present in the liquid nicotine will contribute to the total weight of the aerosol former in the suspension.

[0059] In other embodiments, the nicotine source may be in the form of one or more nicotine salts.

[0060] The aerosol-generating suspension of the aerosol-generating substrate according to the invention preferably comprises at least about 0.5 weight percent nicotine, based on the total weight of the aerosol-generating suspension (including water, if present). Preferably, the aerosol-generating suspension comprises at least about 0.75 weight percent nicotine, and more preferably at least about 1 weight percent nicotine.

[0061] Preferably, the aerosol-generating suspension contains up to about 5 weight percent nicotine, more preferably up to about 4.5 weight percent nicotine, and even more preferably at least about 4 weight percent nicotine.

[0062] For example, the aerosol-generating suspension may contain from about 0.5 weight percent to about 5 weight percent nicotine, or from about 0.75 weight percent to about 4.5 weight percent nicotine, or from about 1 weight percent to about 4 weight percent nicotine.

[0063] The liquid solvent of the aerosol-generating suspension preferably further comprises water. It has been found that including water in the liquid solvent is advantageous because it acts as a heat transfer agent that enhances the vaporization of the aerosol former and nicotine. For example, if the aerosol-generating substrate comprises a susceptor element, as described below, the presence of water in the aerosol-generating suspension may further help to dissipate heat generated from the susceptor element during use. This effect may also be useful in other heating means. As the water in the liquid solvent heats, the liquid solvent vaporizes and the resulting water vapor migrates to parts of the aerosol-generating substrate that may be further from the heat source. By condensing these other parts of the aerosol-generating substrate, heat is released, which is believed to enhance the vaporization of glycerol and nicotine (if present) from the aerosol-generating substrate.

[0064] The inclusion of water in the liquid solvent has been found to provide a significant increase in the amount of nicotine delivered in the aerosol generated upon heating of an aerosol-generating substrate according to the invention due to improved heat transfer within the aerosol-generating substrate, and in some cases, the inclusion of water has been found to increase the amount of nicotine delivered per puff from a tobacco-containing aerosol-generating substrate according to the invention by 50 to 100 percent compared to a similar substrate without water.

[0065] Preferably, the aerosol-generating suspension comprises at least about 5 percent water by weight, more preferably at least about 7.5 percent water by weight, and even more preferably at least about 10 percent water by weight, based on the total weight of the aerosol-generating suspension.

[0066] Preferably, the aerosol-generating suspension contains up to about 30 percent water by weight, more preferably up to about 25 percent water by weight, and even more preferably up to about 20 percent water by weight.

[0067] For example, the aerosol-generating suspension may include about 5 weight percent to 30 weight percent water, or about 7.5 weight percent to 25 weight percent water, or about 10 weight percent to 20 weight percent water.

[0068] Preferably, the aerosol-generating substrate according to the invention comprises up to about 25 percent by weight water, based on the total weight of the aerosol-generating substrate including the aerosol-generating suspension and the porous medium, more preferably up to about 15 percent by weight water, and even more preferably up to about 10 percent by weight water, based on the total weight of the aerosol-generating substrate.

[0069] Aerosol-generating articles according to the present invention preferably contain a maximum of about 75 milligrams of water per rod of aerosol-generating substrate, more preferably a maximum of about 60 milligrams of water per rod of aerosol-generating substrate, and even more preferably a maximum of about 40 milligrams of water per rod of aerosol-generating substrate.

[0070] Instead of, or in addition to, including water in the liquid vehicle of the aerosol-generating suspension, the liquid vehicle may further include an acid.

[0071] Preferably, the liquid medium comprises one or more organic acids. Even more preferably, the liquid medium comprises one or more carboxylic acids.

[0072] Carboxylic acids suitable for use in the aerosol-generating substrates according to the present invention include, but are not limited to, 2-ethylbutyric acid, acetic acid, adipic acid, benzoic acid, butyric acid, cinnamic acid, cycloheptane-carboxylic 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.

[0073] In particularly preferred embodiments, the acid is lactic acid, levulinic acid, benzoic acid, levulinic acid, fumaric acid, or acetic acid. Most preferably, the acid is lactic acid.

[0074] It has been found that the inclusion of acid advantageously stabilizes dissolved species, especially nicotine, in the aerosol generating suspension.Without intending to be bound by theory, it is understood that acid interacts with nicotine molecules, and as a result, protonated nicotine can be stabilized.Because protonated nicotine is non-volatile, it is more easily found in the liquid or particle phase, rather than the vapor phase of the aerosol obtained by heating the aerosol generating element.Therefore, it can minimize the loss of nicotine during the manufacture of the aerosol generating element, and advantageously ensure a higher and better controlled nicotine delivery to consumers.

[0075] Preferably, the aerosol-generating suspension has a pH of at least about 6, more preferably at least about 6.5, and more preferably at least about 7.

[0076] The aerosol-generating suspension preferably has a pH of at most about 9, more preferably at most about 8.5, more preferably at most about 8. For example, the aerosol-generating suspension may have a pH of from about 6 to about 9, or from about 6.5 to about 8.5, or from about 7 to about 8.

[0077] The aerosol-generating suspension preferably contains at least about 0.5 weight percent acid, more preferably at least about 0.75 weight percent acid, and even more preferably at least about 1 weight percent acid, based on the total weight of the aerosol-generating suspension (including water, if present).

[0078] Preferably, the aerosol-generating suspension contains up to about 5 weight percent acid, more preferably up to about 4 weight percent acid, and even more preferably up to about 2.5 weight percent acid.

[0079] For example, the aerosol-generating suspension may include about 0.5 weight percent to 5 weight percent acid, or about 0.75 weight percent to 4 weight percent acid, or about 1 weight percent to 2.5 weight percent acid.

[0080] The liquid vehicle may optionally further comprise one or more flavourants. Suitable flavourants are well known to those skilled in the art. The amount of flavourant in the aerosol-generating suspension is preferably adjusted to provide a desired level of flavourant within the aerosol-generating substrate.

[0081] Suitable flavorants for use in the aerosol-generating substrates of the present invention include, but are not limited to, tobacco, menthol, mint such as peppermint or spearmint, cocoa, licorice, fruit (such as citrus), gamma octalactone, vanillin, spice (such as cinnamon), methyl salicylate, linalool, eugenol, eucalyptol, bergamot oil, eugenol oil, geranium oil, lemon oil, ginger oil, and tobacco flavoring.

[0082] In certain embodiments, the flavoring agent comprises a non-tobacco plant extract, or an essential oil.

[0083] The resulting suspension of the inert powder in the liquid solvent preferably has a relatively high viscosity so that the aerosol-generating suspension is of a paste-like texture. The aerosol-generating suspension is preferably in the form of a paste. This facilitates application of the aerosol-generating suspension onto a porous medium and also optimizes retention of the aerosol-generating suspension within the aerosol-generating substrate during storage and use. Providing a relatively high viscosity advantageously prevents settling of the inert powder in the liquid solvent. As defined above, viscosity is primarily defined by the weight ratio of the liquid solvent, including one or more aerosol formers, to the inert powder, with a higher proportion of inert powder providing a more viscous suspension. The aerosol-generating suspension is preferably substantially free of gelling agents, so there is no gelling of the suspension, which may affect the viscosity.

[0084] The weight ratio of liquid solvent to inert powder in the aerosol-generating suspension is preferably at least about 1, more preferably at least about 1.5, and even more preferably at least about 2.

[0085] Preferably, the weight ratio of liquid solvent to inert powder in the aerosol-generating suspension is up to about 4, more preferably up to about 4.5, and more preferably up to about 5. For example, the weight ratio of liquid solvent to inert powder can be from about 1 to about 5, or from about 1.5 to about 4.5, or from about 2 to about 4.

[0086] The weight ratio of inert powder to liquid solvent in the aerosol-generating suspension is preferably at least about 0.2, more preferably at least about 0.25, and even more preferably at least about 0.3.

[0087] Preferably, the weight ratio of inert powder to liquid solvent in the aerosol-generating suspension is at most about 1, more preferably at most about 0.8, and even more preferably at most about 0.75. For example, the weight ratio of inert powder to liquid solvent can be from about 0.2 to about 1, or from about 0.25 to about 0.8, or from about 0.3 to about 0.75.

[0088] The weight ratio of liquid solvent to total solids in the aerosol-generating suspension is preferably at least about 1, more preferably at least about 1.5, and even more preferably at least about 1.75. Total solids includes inert powders and any optional ingredients in solid form.

[0089] Preferably, the weight ratio of liquid solvent to total solids in the aerosol-generating suspension is up to about 5, more preferably up to about 4, and more preferably up to about 3. For example, the weight ratio of liquid solvent to total solids can be from about 1 to about 5, or from about 1.5 to about 4, or from about 1.75 to about 3.

[0090] The weight ratio of total solids to liquid solvent in the aerosol-generating suspension is preferably at least about 0.2, more preferably at least about 0.25, more preferably at least about 0.3, and more preferably at least about 0.4.

[0091] The weight ratio of total solids to liquid solvent in the aerosol-generating suspension is preferably at most about 1, more preferably at most about 0.8, more preferably at most about 0.75, and more preferably at most about 0.6. For example, the weight ratio of plant particles to liquid solvent can be from about 0.2 to about 1, or from about 0.25 to about 0.8, or from about 0.3 to about 0.75, or from about 0.4 to about 0.6.

[0092] Providing this balance of inert powder or total solids with liquid solvent ensures that the aerosol-generating suspension is sufficiently viscous to provide the benefits discussed above.

[0093] As mentioned above, in the aerosol-generating substrate of the present invention, the aerosol-generating suspension is loaded onto a porous medium. The porous medium acts as an inert carrier element to support and retain the aerosol-generating suspension within the aerosol-generating substrate. The porous medium has a porous structure that defines a plurality of pores. The aerosol-generating suspension can be dispersed within the porous structure of the porous medium and thus retained within the plurality of pores. The porous medium may take any suitable form suitable for this purpose and capable of being formed into a cylindrical rod such that the aerosol-generating substrate can be incorporated into an aerosol-generating article as described below.

[0094] The porous medium is preferably formed of a fibrous material. For example, in a preferred embodiment of the present invention, the porous medium is in the form of a fibrous sheet. The porous medium is preferably in the form of a cellulosic sheet formed of a fibrous cellulosic material. Suitable cellulosic materials include, but are not limited to, cotton, viscose, hemp, bamboo, coconut, kenaf, and combinations thereof. Alternatively, the porous medium may be in the form of a non-cellulosic sheet formed of a non-cellulosic material such as silicone or carbon fiber.

[0095] The porous medium is preferably in the form of one or more crimped sheets. As used herein, the term "crimped sheet" means a sheet having a plurality of substantially parallel ridges or corrugations that are generally aligned with the longitudinal axis of the substrate or article. It is particularly preferred that the porous medium comprises one or more crimped cotton sheets.

[0096] One or more sheets forming the porous medium may optionally be assembled to form a plug. As used herein, the term "assembled" means that the sheets forming the porous medium are coiled, folded, or otherwise compressed or contracted in a direction substantially transverse to the cylindrical axis of the plug or rod. The step of "assembling" the sheets may be carried out by any suitable means that provides the requisite transverse compression of the sheets.

[0097] Alternatively, other forms of porous media may be used in the aerosol-generating substrates of the present invention. For example, the porous media may take the form of a porous plug of fibrous material, or a hollow tubular element of fibrous material.

[0098] Preferably, the porous medium comprises from about 10 percent by weight to about 30 percent by weight of the aerosol-generating substrate, or from about 15 percent by weight to about 25 percent by weight of the aerosol-generating substrate, based on the total weight of the aerosol-generating substrate including the porous medium and the aerosol-generating suspension.

[0099] Aerosol-generating articles according to the present invention preferably contain from about 40 milligrams to about 80 milligrams of porous medium per rod of aerosol-generating substrate, more preferably from about 50 milligrams to about 70 milligrams of porous medium per rod of aerosol-generating substrate.

[0100] The mass and volume of the porous medium should be selected to provide sufficient retention of the aerosol-generating suspension that is to be incorporated into the aerosol-generating substrate. The amount of aerosol-generating suspension that can be retained by the porous medium will depend in part on the properties of the porous medium, particularly the porosity of the porous medium.

[0101] Typically, it is desirable to maximize the weight ratio of the aerosol-generating suspension to the porous medium to optimize the level of aerosol that can be generated from the aerosol-generating substrate. The weight ratio of the aerosol-generating suspension to the porous medium in the aerosol-generating substrate is preferably at least about 3, and more preferably at least about 4. The weight ratio of the aerosol-generating suspension to the porous medium in the aerosol-generating substrate is preferably no greater than about 8. The ratio should be adapted to allow the aerosol-generating suspension to be retained within the porous medium without significant leakage of the aerosol-generating suspension prior to use.

[0102] The aerosol-generating suspension may be applied to the porous medium using any suitable means. As noted above, the aerosol-generating suspension typically has a relatively high viscosity and is in the form of a thick paste that can be spread onto one or more surfaces of the porous medium. The aerosol-generating suspension may at least partially impregnate the porous medium.

[0103] Once the porous medium is loaded with the aerosol-generating suspension, the combination is preferably formed into a rod shape and surrounded along at least a portion of its length by one or more wrappers. The one or more wrappers may include a paper wrapper or a non-paper wrapper, or both. Suitable paper wrappers for use in certain embodiments of the invention are known in the art and include, but are not limited to, cigarette paper and filter plug wrap.

[0104] In certain embodiments, the resulting rod of aerosol-generating substrate includes one or more susceptor elements, for example, one or more susceptor elements may be included in an aerosol-generating substrate that is intended to be heated by induction, as described below.

[0105] The one or more susceptor elements may be a plurality of susceptor particles that may be deposited on or embedded within the aerosol-generating substrate. If the porous medium of the aerosol-generating substrate is in the form of one or more sheets, the plurality of susceptor particles may be deposited on or embedded within the one or more sheets. The susceptor particles may, for example, be fixed by the substrate in sheet form and remain in their initial position. The susceptor particles may preferably be uniformly distributed in the porous medium of the aerosol-generating substrate. Due to the fine particle nature of the susceptor, heat is generated according to the distribution of the particles within the porous medium. Alternatively, susceptors in the form of one or more sheets, strips, pieces, or rods may also be used adjacent to or embedded within the porous medium. In one embodiment, the aerosol-forming substrate includes one or more susceptor strips. For example, a rod of the aerosol-generating substrate may include an elongated susceptor element extending longitudinally through the substrate. In another embodiment, the susceptor is present in an aerosol generating device.

[0106] The susceptor may have a heat loss of more than 0.05 Joules / kilogram, preferably more than 0.1 Joules / kilogram. Heat loss is the capacity of the susceptor to transfer heat to the surrounding material. Since the susceptor particles are preferably uniformly distributed within the aerosol-generating substrate, uniform heat loss from the susceptor particles is achieved, thus resulting in a uniform heat distribution within the aerosol-generating substrate, which may result in a uniform temperature distribution within the aerosol-generating article. It has been found that a specific minimum heat loss of 0.05 Joules / kilogram in the susceptor particles allows the aerosol-generating substrate to be heated to a substantially uniform temperature to provide aerosol generation. In such an embodiment, the average temperature reached within the aerosol-generating substrate is preferably about 200 degrees Celsius to about 280 degrees Celsius.

[0107] The reduction of the risk of overheating of the aerosol-generating substrate may be supported by the use of a susceptor material with a Curie temperature, which allows the heating process due to hysteresis losses to reach only up to a certain maximum temperature. The susceptor may have a Curie temperature of about 200 degrees Celsius to about 450 degrees Celsius, preferably about 240 degrees Celsius to about 400 degrees Celsius, for example about 280 degrees Celsius. When the susceptor material reaches its Curie temperature, it changes magnetic properties. At the Curie temperature, the susceptor material changes from a ferromagnetic phase to a paramagnetic phase. At this point, heating based on energy losses due to the orientation of the ferromagnetic regions stops. Thereafter, further heating is mainly based on the formation of eddy currents, such that the heating process is automatically reduced when the Curie temperature of the susceptor material is reached. The susceptor material and its Curie temperature are preferably matched to the composition of the aerosol-generating substrate in order to achieve optimal temperature and temperature distribution within the aerosol-generating substrate for optimal aerosol generation.

[0108] In some preferred embodiments according to the present invention, the susceptor is made of ferrite. Ferrite is a ferromagnetic material with high magnetic permeability and is particularly suitable as a susceptor material. The main component of ferrite is iron. Other metallic components (e.g. zinc, nickel, manganese) or non-metallic components (e.g. silicon) may be present in various amounts. Ferrite is a relatively inexpensive commercially available material. Ferrite is available in particulate form within the size range of the particles used in the particulate plant material forming the homogenized rosemary material according to the present invention. The particles are preferably fully sintered ferrite powders, such as, for example, FP160, FP215, FP350 by PPT (Indiana, USA).

[0109] The aerosol-generating substrate preferably has a length of from about 5 mm to about 20 mm, more preferably from about 8 mm to about 15 mm, more preferably from about 10 mm to about 12 mm.

[0110] The aerosol-generating substrate preferably has an outer diameter of about 5 mm to about 12 mm, more preferably about 5 mm to about 10 mm, and even more preferably about 6 mm to about 8 mm. Typically, the aerosol-generating substrate has an outer diameter of approximately 7.2 mm.

[0111] As defined above, the present invention further provides a method for producing an aerosol-generating substrate according to the invention, as explained in detail above.

[0112] In the first step of the method according to the invention, a liquid solvent is prepared. As mentioned above, the liquid solvent preferably comprises one or more aerosol formers, which are combined with water to form an aqueous solution, and a nicotine source. The nicotine source is preferably combined with one or more aerosol formers, which are then mixed with water (if present) to form a homogenous solution. If an acid is included in the liquid solvent, it may be dissolved in water before the water is combined with the nicotine and aerosol formers.

[0113] In the second step, an inert powder is provided having a desired particle size distribution.

[0114] In a third step, an inert powder is added to and mixed with the liquid vehicle to form an aerosol-generating suspension having a paste-like consistency. The aerosol-generating suspension is mixed until the inert powder is substantially evenly distributed in the liquid vehicle.

[0115] In a fourth step, the aerosol-generating suspension is deposited onto a porous medium to form the aerosol-generating substrate, for example, the aerosol-generating suspension may be extruded onto the porous medium.

[0116] The porous medium with the aerosol-generating suspension loaded thereon may then be formed into a rod, and the rod may be surrounded by an outer wrapper using suitable means.

[0117] The aerosol-generating suspension is preferably substantially free of gelling agents. As defined above in relation to the aerosol-generating substrate, the aerosol-generating suspension formed by the method of the present invention is defined as non-colloidal.

[0118] The method according to the invention preferably does not include a gelling step.

[0119] In some embodiments, the method according to the present invention may not include a drying step.

[0120] An aerosol-generating article according to the present invention comprises a rod of aerosol-generating substrate as detailed above surrounded by an outer wrapper. The rod of aerosol-generating substrate is preferably combined with one or more additional components.

[0121] The aerosol-generating article according to the invention may optionally include a support element comprising at least one hollow tube immediately downstream of the aerosol-generating substrate. One function of the tube is to position the aerosol-generating substrate towards the distal end of the aerosol-generating article so that it can come into contact with the heating element. The tube acts to prevent the aerosol-generating substrate from being forced along the aerosol-generating article towards other downstream elements when the heating element is inserted into the aerosol-generating substrate. The tube also acts as a spacer element to separate the downstream elements from the aerosol-generating substrate. The tube may be made of any material such as cellulose acetate, polymer, cardboard, or paper.

[0122] Alternatively or additionally, the aerosol-generating article according to the invention optionally comprises an aerosol cooling element downstream of the aerosol-generating substrate and immediately downstream of the hollow tube forming the support element. In use, the aerosol formed by the volatile compounds released from the aerosol-generating substrate passes through and is cooled by the aerosol cooling element before being inhaled by the user. The low temperature allows the vapor to condense into an aerosol. The aerosol cooling element may be a hollow tube, such as a hollow cellulose acetate tube or a cardboard tube, which may be similar to the support element immediately downstream of the aerosol-generating substrate. The aerosol cooling element may be a hollow tube with the same outer diameter but with an inner diameter smaller or larger than the hollow tube forming the support element. In one embodiment, the aerosol cooling element rolled in paper comprises one or more longitudinal channels made of any suitable material, such as metal foil, foil-laminated paper, polymeric sheets, preferably made of synthetic polymers, and substantially non-porous paper or cardboard. In some embodiments, the paper-wrapped aerosol cooling element may include one or more sheets made of a material selected from the group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), paper laminated with a polymeric sheet, and aluminum foil. Alternatively, the aerosol cooling element may be made of woven or non-woven filaments of a material selected from the group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), and cellulose acetate (CA). In a preferred embodiment, the aerosol cooling element is an assembly of crimped sheets of polylactic acid wrapped in filter paper. In another preferred embodiment, the aerosol cooling element includes longitudinal channels and is made of woven filaments of a synthetic polymer, such as polylactic acid filaments wrapped in paper.

[0123] One or more additional hollow tubes may be provided downstream of the aerosol cooling element.

[0124] The aerosol-generating article according to the present invention may further comprise a filter or mouthpiece downstream of the aerosol-generating substrate and, if present, the support element and the aerosol cooling element. The filter or mouthpiece may comprise one or more filter elements. The filter may comprise one or more filter materials for removing particulate components, gaseous components, or a combination thereof. Suitable filter materials are known in the art and include, but are not limited to, fibrous filter materials such as cellulose acetate tow and paper, adsorbents such as activated alumina, zeolites, molecular sieves, and silica gel, biodegradable polymers including polylactic acid (PLA), Matabi®, hydrophobic viscose fibers, and bioplastics, and combinations thereof. The filter may be located at the downstream end of the aerosol-generating article. The filter may be a cellulose acetate filter plug. The filter may have a length of about 5 mm to about 15 mm, or about 5 mm to about 10 mm.

[0125] An aerosol-generating article according to the invention may include an oral end cavity at the downstream end of the article. The oral end cavity may be defined by one or more wrappers extending downstream from the filter or mouthpiece. Alternatively, the oral end cavity may be defined by a separate tubular element provided at the downstream end of the aerosol-generating article.

[0126] Preferably, the aerosol-generating article according to the invention further comprises a ventilation zone provided at a location along the aerosol-generating article, for example the aerosol-generating article may be provided at a location along a hollow tube provided downstream of the aerosol-generating substrate.

[0127] The aerosol-generating article according to the invention may optionally further comprise an upstream element at the upstream end of the aerosol-generating substrate. The upstream element may be a porous plug element, such as a plug of fibrous filtration material such as cellulose acetate. Alternatively, the upstream element may be in the form of a hollow tubular element.

[0128] In a preferred embodiment of the invention, the aerosol-generating article comprises an aerosol-generating substrate, at least one hollow tube downstream of the aerosol-generating substrate, and a filter downstream of the at least one hollow tube. Optionally, the aerosol-generating article further comprises an oral end cavity at the downstream end of the filter. Preferably, a ventilation zone is provided at a location along the at least one hollow tube.

[0129] In a particularly preferred embodiment having this arrangement, the aerosol-generating article comprises an aerosol-generating substrate, an upstream element at the upstream end of the aerosol-generating substrate, a support element downstream of the aerosol-generating substrate, an aerosol cooling element downstream of the support element, and a filter downstream of the aerosol cooling element. Both the support element and the aerosol cooling element are preferably in the form of a hollow tube. The aerosol-generating substrate preferably comprises an elongated susceptor element extending longitudinally through the substrate.

[0130] In a further preferred embodiment, the aerosol-generating article comprises an aerosol-generating substrate, an upstream element at the upstream end of the aerosol-generating substrate, a single hollow tube downstream of the aerosol-generating substrate, and a filter downstream of the hollow tube.

[0131] The aerosol-generating article of the present invention may optionally comprise a combustible heat source and an aerosol-generating substrate downstream of the combustible heat source, the aerosol-generating substrate being as described above in relation to the first aspect of the present invention.

[0132] For example, a substrate as described herein may be used in a heated aerosol-generating article of the type disclosed in WO-A-2009 / 022232, comprising a combustible carbon-based heat source, an aerosol-generating substrate downstream of the combustible heat source, and a thermally conductive element surrounding and in contact with a rear portion of the combustible carbon-based heat source and an adjacent front portion of the aerosol-generating substrate, although it will be appreciated that a substrate as described herein may also be used in heated aerosol-generating articles comprising combustible heat sources having other configurations.

[0133] Alternatively, the aerosol-generating articles according to the present disclosure may be adapted for use in an electrically operated aerosol generating system in which the aerosol-generating substrate of the heated aerosol-generating article is heated by an electrical heat source.

[0134] For example, an aerosol-generating substrate as described herein may be used in heated aerosol-generating articles of the type disclosed in EP-A-0 822 760.

[0135] The heating element of such an aerosol-generating device may be in any suitable form for conducting heat. Heating of the aerosol-generating substrate may be accomplished internally, externally, or both. The heating element may preferably be a heater blade or pin adapted to be inserted into the substrate such that the substrate is heated from the inside. The heating element may preferably partially or completely surround the substrate and heat the substrate circumferentially from the outside.

[0136] The aerosol-generating system may be an electrically operated aerosol-generating system equipped with an induction heating device. The induction heating device typically includes an induction source configured to be coupled to the susceptor, which may be provided external to the aerosol-generating substrate or internal to the aerosol-generating substrate. The induction source generates an alternating electromagnetic field, which induces magnetization or eddy currents in the susceptor. The susceptor may heat up as a result of hysteresis losses or induced eddy currents, which heat the susceptor through ohmic or resistive heating.

[0137] The electrically operated aerosol generating system comprising an induction heating device also comprises an aerosol-generating article having an aerosol-generating substrate and a susceptor in thermal proximity to the aerosol-generating substrate. Typically, the susceptor is in direct contact with the aerosol-generating substrate and heat is transferred from the susceptor to the aerosol-generating substrate primarily by conduction. Examples of electrically operated aerosol generating systems comprising an induction heating device and an aerosol-generating article having a susceptor are described in WO-A1-95 / 27411 and WO-A1-2015 / 177255.

[0138] The aerosol-generating substrate of the present invention is preferably adapted to provide an optimized release of aerosol when heated to a temperature of about 230° C. to 270° C. The aerosol-generating article according to the present invention is therefore particularly suitable for use in conjunction with an aerosol-generating device in which the aerosol-generating substrate is heated externally or by induction, as described above. In such devices the aerosol-generating substrate is typically heated to a temperature significantly lower than that in aerosol-generating devices with internal heating means.

[0139] Below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein. References in these examples to an aerosol-generating substrate according to the invention should also be taken to refer to the aerosol-generating substrate of an aerosol-generating article according to the invention.

[0140] Example 1. An aerosol-generating substrate for an aerosol-generating article, comprising a porous medium loaded with an aerosol-generating suspension of an inert powder in a liquid solvent that includes one or more aerosol formers.

[0141] Example 2. The aerosol-generating substrate of Example 1, wherein the aerosol-generating suspension comprises at least 20 weight percent of an inert powder.

[0142] Example 3. The aerosol-generating substrate of Example 1 or Example 2, wherein the aerosol-generating suspension comprises at least 30 weight percent of one or more aerosol formers.

[0143] Example 4. An aerosol-generating substrate as described in any of Examples 1-3, wherein the aerosol-generating suspension comprises up to 50 weight percent of the inert powder.

[0144] Example 5. An aerosol-generating substrate as described in any of Examples 1 to 4, wherein the aerosol-generating substrate comprises at least 8 percent by weight of an inert powder.

[0145] Example 6. An aerosol-generating substrate as described in any one of Examples 1 to 5, wherein the aerosol-generating substrate comprises up to 40 percent by weight of an inert powder.

[0146] Example 7. An aerosol-generating substrate as described in any one of Examples 1 to 6, in which the inert powder is formed from a plant material.

[0147] Example 8. The aerosol-generating substrate of Example 7, wherein the inert powder is an inert cellulose powder.

[0148] Example 9. An aerosol-generating substrate as described in any one of Examples 1 to 6, wherein the inert powder is formed from one or more inorganic compounds.

[0149] Example 10. The aerosol-generating substrate of Example 9, wherein the inert powder comprises silicon dioxide, calcium carbonate, zeolite, alumina, clay, or a combination thereof.

[0150] Example 11. An aerosol-generating substrate as described in any one of Examples 1 to 6, wherein the inert powder comprises one or more polysaccharides.

[0151] Example 12. The aerosol-generating substrate according to any one of Examples 1 to 11, wherein the inert powder has an average particle size of 20 microns to 200 microns.

[0152] Example 13. An aerosol-generating substrate as defined in any of Examples 1 to 12, wherein the liquid solvent of the aerosol-generating suspension is aqueous.

[0153] Example 14. An aerosol-generating substrate as defined in any of Examples 1 to 13, wherein the liquid solvent of the aerosol-generating suspension comprises glycerol.

[0154] Example 15. An aerosol-generating substrate according to any of Examples 1-14, wherein the aerosol-generating suspension comprises at least 35 weight percent of one or more aerosol formers.

[0155] Example 16. An aerosol-generating substrate according to any one of Examples 1 to 15, wherein the aerosol-generating suspension comprises up to 90 weight percent of one or more aerosol formers.

[0156] Example 17. An aerosol-generating substrate as described in any of Examples 1 to 16, wherein the aerosol-generating substrate comprises at least 25 weight percent of one or more aerosol formers.

[0157] Example 18. An aerosol-generating substrate as defined in any one of Examples 1 to 17, wherein the aerosol-generating substrate comprises up to 75 weight percent of one or more aerosol formers.

[0158] Example 19. An aerosol-generating substrate as described in any of Examples 1 to 18, wherein the aerosol-generating substrate comprises at least 25 weight percent of one or more aerosol formers.

[0159] Example 20. An aerosol-generating substrate as defined in any of Examples 1 to 19, wherein the liquid solvent of the aerosol-generating suspension comprises water.

[0160] Example 21. The aerosol-generating substrate of Example 20, wherein the liquid vehicle of the aerosol-generating suspension comprises at least 5 weight percent water.

[0161] Example 22. The aerosol-generating substrate of Example 20 or Example 21, wherein the liquid solvent of the aerosol-generating suspension comprises up to 30 weight percent water.

[0162] Example 23. An aerosol-generating substrate as defined in any one of Examples 20 to 22, wherein the aerosol-generating substrate comprises up to 25 weight percent water.

[0163] Example 24. The aerosol-generating substrate according to any one of Examples 1 to 23, wherein the nicotine source is a liquid nicotine source.

[0164] Example 25. The aerosol-generating substrate of Example 24, wherein the nicotine source is liquid nicotine.

[0165] Example 26. The aerosol-generating substrate of Example 24, wherein the nicotine source is in the form of a liquid nicotine extract.

[0166] Example 27. An aerosol-generating substrate as described in any one of Examples 1 to 23, wherein the nicotine source is in the form of one or more nicotine salts.

[0167] Example 28. An aerosol-generating substrate as described in any of Examples 1-27, wherein the aerosol-generating suspension comprises at least 0.5 weight percent nicotine.

[0168] Example 29. An aerosol-generating substrate as described in any of Examples 1-28, wherein the aerosol-generating suspension comprises up to 5 weight percent nicotine.

[0169] Example 30. An aerosol-generating substrate as defined in any one of Examples 1 to 29, wherein the liquid solvent of the aerosol-generating suspension further comprises one or more acids.

[0170] Example 31. The aerosol-generating substrate of Example 30, wherein the aerosol-generating suspension comprises benzoic acid, lactic acid, fumaric acid, levulinic acid, acetic acid, or a combination thereof.

[0171] Example 32. The aerosol-generating substrate of Example 30 or Example 31, wherein the aerosol-generating suspension comprises at least 0.5 weight percent acid.

[0172] Example 33. The aerosol-generating substrate of any of Examples 30-32, wherein the aerosol-generating suspension comprises up to 5 weight percent acid.

[0173] Example 34. An aerosol-generating substrate as defined in any of Examples 1 to 33, wherein the pH of the aerosol-generating suspension is at least 6.

[0174] Example 35. An aerosol-generating substrate as defined in any one of Examples 1 to 34, wherein the pH of the aerosol-generating suspension is a maximum of 9.

[0175] Example 36. An aerosol-generating substrate as defined in any of Examples 1 to 35, wherein the weight ratio of liquid solvent to inert powder in the aerosol-generating suspension is at least 1.

[0176] Example 37. An aerosol-generating substrate as defined in any of Examples 1 to 36, wherein the weight ratio of liquid solvent to inert powder in the aerosol-generating suspension is up to 4.

[0177] Example 38. An aerosol-generating substrate as described in any of Examples 1 to 37, wherein the weight ratio of liquid solvent to total solids in the aerosol-generating suspension is at least 1.

[0178] Example 39. An aerosol-generating substrate as defined in any of Examples 1 to 38, wherein the weight ratio of liquid solvent to total solids in the aerosol-generating suspension is up to 4.

[0179] Example 40. An aerosol-generating substrate as described in any of Examples 1 to 39, wherein the porous medium is formed from a fibrous material.

[0180] Example 41. An aerosol-generating substrate as described in Example 40, wherein the fibrous material is in the form of a cellulosic sheet.

[0181] Example 42. An aerosol-generating substrate as described in Example 40 or Example 41, wherein the porous medium comprises one or more crimped sheets.

[0182] Example 43. An aerosol-generating substrate as claimed in any of Examples 1 to 42, wherein the porous medium comprises between 10 percent and 30 percent by weight of the aerosol-generating substrate.

[0183] Example 44. An aerosol-generating substrate as claimed in any of Examples 1 to 43, wherein the weight ratio of the aerosol-generating suspension to the porous medium within the aerosol-generating substrate is at least 3.

[0184] Example 45. An aerosol-generating substrate as defined in any of Examples 1 to 44, wherein the weight ratio of the aerosol-generating suspension to the porous medium within the aerosol-generating substrate is up to 8.

[0185] Example 46. An aerosol-generating substrate according to any one of Examples 1 to 45, further comprising one or more susceptor elements.

[0186] Example 47. The aerosol-generating substrate as defined in any one of Examples 1 to 46, wherein the aerosol-generating substrate has a length of from 5 mm to 12 mm.

[0187] Example 48. A method for producing the aerosol-generating substrate according to any one of Examples 1 to 47, comprising the steps of: providing a liquid vehicle comprising one or more aerosol formers, a nicotine source, and optionally water; Providing an inert powder; mixing the inert powder with a liquid solvent to form a suspension of the inert powder in the liquid solvent; and depositing the suspension onto a porous medium to form an aerosol-generating substrate.

[0188] Example 49. An aerosol-generating article comprising a rod of the aerosol-generating substrate of any of Examples 1 to 48 surrounded by an outer wrapper.

[0189] Example 50. The aerosol-generating article of example 49, further comprising a support element downstream of the aerosol-generating substrate, the support element comprising at least one hollow tube.

[0190] Example 51. The aerosol-generating article of example 49 or example 50, further comprising an aerosol cooling element downstream of the aerosol-generating substrate.

[0191] Example 52. The aerosol-generating article according to any one of Examples 49 to 51, further comprising a mouthpiece downstream of the aerosol-generating substrate.

[0192] Example 53. The aerosol-generating article of any one of Examples 49 to 51, further comprising an upstream element at the upstream end of the aerosol-generating substrate.

[0193] Example 54. An aerosol-generating article as described in any of Examples 49 to 53, comprising an upstream element at the upstream end of the aerosol-generating substrate, a support element downstream of the aerosol-generating substrate, an aerosol cooling element downstream of the support element, and a filter downstream of the aerosol cooling element.

[0194] Specific embodiments will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0195] [Figure 1] FIG. 1 provides a schematic side cross-sectional view (not to scale) of an aerosol-generating article according to a first embodiment of the invention suitable for induction heating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0196] 1 comprises a rod 12 of aerosol-generating substrate 12 and a downstream section 14 located downstream of the rod 12 of aerosol-generating substrate. In addition, the aerosol-generating article 10 comprises an upstream section 16 located upstream of the rod 12 of aerosol-generating substrate. Thus, the aerosol-generating article 10 may extend from an upstream or distal end 18 to a downstream or oral end 20.

[0197] The aerosol-generating article 10 has an overall length of about 45 millimeters.

[0198] The downstream section 14 comprises a support element 22 located immediately downstream of the rod 12 of the aerosol-generating substrate, the support element 22 being in longitudinal alignment with the rod 12. In the embodiment of Figure 1, the upstream end of the support element 22 abuts the downstream end of the rod 12 of the aerosol-generating substrate. In addition, the downstream section 14 comprises an aerosol cooling element 24 located immediately downstream of the support element 22, the aerosol cooling element 24 being in longitudinal alignment with the rod 12 and the support element 22. In the embodiment of Figure 1, the upstream end of the aerosol cooling element 24 abuts the downstream end of the support element 22.

[0199] The support element 22 may include a first hollow tubular segment 26. The first hollow tubular segment 26 is provided in the form of a hollow cylindrical tube made from cellulose acetate. The first hollow tubular segment 26 defines an interior cavity 28 extending entirely from an upstream end 30 of the first hollow tubular segment to a downstream end 32 of the first hollow tubular segment 20. The interior cavity 28 is substantially empty, thus allowing substantially unlimited airflow along the interior cavity 28. The first hollow tubular segment 26, and consequently the support element 22, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the first hollow tubular segment 26 (which is substantially the RTD of the support element 22) is substantially 0 millimeters H2O.

[0200] The first hollow tubular segment 26 has a length of approximately 7 millimeters and an outside diameter of approximately 7.25 millimeters.

[0201] The aerosol cooling element 24 comprises a second hollow tubular segment 34. The second hollow tubular segment 34 is provided in the form of a hollow cylindrical tube made of cardboard. The second hollow tubular segment 34 defines an interior cavity 36 that extends from an upstream end 38 of the second hollow tubular segment all the way to a downstream end 40 of the second hollow tubular segment 34. The interior cavity 36 is substantially empty, thereby allowing substantially unrestricted airflow along the interior cavity 36. The second hollow tubular segment 34, and consequently the aerosol cooling element 24, does not substantially contribute to the overall RTD of the aerosol-generating article 10. More specifically, the RTD of the second hollow tubular segment 34 (which is essentially the RTD of the aerosol cooling element 24) is substantially 0 millimeters H2O.

[0202] The second hollow tubular segment 34 has a length of approximately 17 millimeters and an outside diameter of approximately 7.25 millimeters.

[0203] The aerosol-generating article 10 includes a ventilation zone (not shown) provided at a location along the second hollow tubular segment 34 .

[0204] 1, the downstream section 14 further comprises a mouthpiece element 42 at the downstream end of the aerosol-generating article 10. More specifically, the mouthpiece element 42 is positioned immediately downstream of the aerosol cooling element 24. As shown in the drawing of FIG.

[0205] Mouthpiece element 42 is provided in the form of a cylindrical plug of low density cellulose acetate.

[0206] Mouthpiece element 42 has a length of approximately 5 millimeters and an outer diameter of approximately 7.25 millimeters.

[0207] The rod 12 comprises an aerosol-generating substrate according to the present invention, which comprises an aerosol-generating suspension loaded onto a porous medium. The porous medium is in the form of a crimped cotton sheet. The cotton sheet loaded with the aerosol-generating suspension is assembled, crimped and wrapped in filter paper to form the rod 12. An example of a suitable aerosol-generating suspension for forming the aerosol-generating substrate is shown in Table 1 below.

[0208] The aerosol-generating substrate rod 12 has an outer diameter of about 7.25 millimeters, and a length of about 7 millimeters.

[0209] The aerosol-generating article 10 further comprises an elongated susceptor element 44 within the rod 12 of the aerosol-generating substrate. More specifically, the susceptor element 44 is disposed substantially longitudinally within the aerosol-generating substrate such that the susceptor element 44 is generally parallel to the longitudinal direction of the rod 12. As shown in the drawing of Figure 1, the susceptor element 44 is positioned at a radially central location within the rod and effectively extends along the longitudinal axis of the rod 12.

[0210] The susceptor element 44 extends completely from the upstream end to the downstream end of the rod 12. In practice, the susceptor element 44 has substantially the same length as the rod 12 of the aerosol-generating substrate.

[0211] In the embodiment of Fig. 1, the susceptor element 44 is provided in the form of a strip, having a length of about 12 millimeters, a thickness of about 60 micrometers, and a width of about 4 millimeters. The upstream section 16 comprises an upstream element 46 located immediately upstream of the rod 12 of the aerosol-generating substrate, the upstream element 46 being longitudinally aligned with the rod 12. In the embodiment of Fig. 1, the downstream end of the upstream element 46 abuts the upstream end of the rod 12 of the aerosol-generating substrate. This advantageously prevents the susceptor element 44 from becoming dislodged. Furthermore, this ensures that a consumer cannot accidentally come into contact with the heated susceptor element 44 after use.

[0212] The upstream element 46 is provided in the form of a cylindrical plug of cellulose acetate surrounded by a rigid wrapper. The upstream element 46 has a length of approximately 5 millimeters.

[0213] In an alternative embodiment, the aerosol-generating article may be manufactured without an elongated susceptor element in the aerosol-generating substrate rod 12. Such an embodiment would be suitable for use in an aerosol-generating device that includes an internal or external heating device for heating the aerosol-generating substrate during use, as described above. EXAMPLES

[0214] As discussed above with reference to the Figures, an aerosol-generating suspension for use in an aerosol-generating substrate according to the present invention may be prepared having the composition shown in Table 1. [Table 1]

[0215] To form the aerosol-generating suspension, a liquid vehicle was prepared by first dissolving an acid in water, then combining an aerosol former with nicotine, and then mixing the aqueous and aerosol former solutions to form a homogenous solution. An inert powder was then added to the liquid vehicle to form a heterogeneous suspension. The resulting suspension was deposited onto a porous medium in the form of a crimped cotton sheet, which was assembled and crimped to form a rod that was surrounded by a wrapper.

Claims

1. 1. An aerosol-generating article comprising an aerosol-generating substrate, the aerosol-generating substrate comprising a porous medium filled with an aerosol-generating suspension of an inert powder in a liquid solvent, the liquid solvent comprising one or more aerosol formers and a nicotine source, the aerosol-generating suspension comprising at least 20 percent by weight of the inert powder and at least 30 percent by weight of the one or more aerosol formers.

2. 2. The aerosol-generating article of claim 1, wherein the inert powder has an average particle size of from 20 microns to 300 microns.

3. 10. The aerosol-generating article of claim 1, wherein the inert powder comprises one or more of silicon dioxide, calcium carbonate, zeolite, alumina, and clay.

4. 10. The aerosol-generating article of claim 1, wherein the nicotine source comprises a liquid tobacco extract.

5. 10. The aerosol-generating article of claim 1, wherein the nicotine source comprises liquid nicotine.

6. 10. The aerosol-generating article of claim 1, wherein the aerosol-generating suspension further comprises an acid.

7. 2. The aerosol-generating article of claim 1, wherein the weight ratio of the liquid solvent to the inert powder in the aerosol-generating suspension is at least 1.

5.

8. 2. The aerosol-generating article of claim 1, wherein the porous medium is formed from a fibrous sheet comprising cellulose fibers.

9. 9. The aerosol-generating article of claim 8, wherein the porous medium comprises a crimped cotton sheet.

10. 10. The aerosol-generating article of claim 1, wherein the liquid vehicle of the aerosol-generating suspension further comprises at least 5 percent by weight of water.

11. 10. The aerosol-generating article of claim 1, wherein the aerosol-generating suspension further comprises a flavoring agent.

12. 2. The aerosol-generating article of claim 1, wherein the weight ratio of the aerosol-generating suspension to the porous medium is at least 3.

13. The aerosol-generating article of claim 1 , further comprising a susceptor element.

14. 2. The aerosol-generating article of claim 1, comprising a rod formed of the aerosol-generating substrate surrounded by an outer wrapper.

15. 10. A method for producing an aerosol-generating substrate for the aerosol-generating article of claim 1, comprising the steps of: providing a liquid vehicle comprising one or more aerosol formers, a nicotine source, and optionally water; providing an inert powder; mixing the inert powder with the liquid solvent to form an aerosol-generating suspension of the inert powder in the liquid solvent; depositing the aerosol-generating suspension onto a porous medium to form the aerosol-generating substrate.

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