JP2024061854A - Aerosol-forming substrates having nitrogen-containing nucleophilic compounds - Google Patents

Abstract

The present invention relates to an aerosol-forming substrate that reduces the formation of undesirable aldehydes in an aerosol generated by heating the aerosol-forming substrate without combustion. The present invention relates to an aerosol-forming substrate that includes the following components: a) one or both of cellulose and a cellulose derivative, b) an aerosol former, c) 0 to 5 weight percent, preferably 0 to 3 weight percent, more preferably 0 to 1 weight percent, and most preferably 0 to 0.5 weight percent tobacco, on a dry weight basis based on the total amount of the aerosol-forming substrate, and d) a nitrogen-containing nucleophilic compound.Selected Figure:

Description

The present invention relates to an aerosol-generating article that includes an aerosol-forming substrate and a substrate portion that includes the aerosol-forming substrate, and also to a system that includes the aerosol-forming article and an aerosol generating device that includes a heated chamber for inserting the aerosol-generating article.

It is known to provide aerosol-generating articles that include an aerosol-forming substrate that includes an aerosol former, such as a polyhydric alcohol and nicotine. The aerosol-generating article is inserted into a heating chamber of an aerosol generating device, and the aerosol-generating article is heated to a temperature at which one or more components of the aerosol-forming substrate are volatilized without burning the aerosol-forming substrate. These non-liquid aerosol-generating articles may or may not include tobacco. It is known that in conventional cigarettes, when tobacco is burned, aldehydes, particularly undesirable formaldehyde, may be formed. However, aldehydes may also be formed when the aerosol-generating article is heated without burning the aerosol-forming substrate. Thus, there is a need to reduce the formation of undesirable aldehydes in the aerosol generated by heating the aerosol-forming substrate without burning it.

According to one embodiment of the present invention,
a) one or both of cellulose and cellulose derivatives,
b) an aerosol former; and
c) from 0 to 5 weight percent, preferably from 0 to 3 weight percent, more preferably from 0 to 1 weight percent, and most preferably from 0 to 0.5 weight percent tobacco on a dry weight basis based on the total amount of the aerosol-forming substrate;
d) a nitrogen-containing nucleophilic compound.

Surprisingly, it has been found that aerosol-forming substrates that are tobacco-free or substantially tobacco-free but that contain one or both of cellulose and cellulose derivatives can produce aerosols with high concentrations of aldehydes, particularly formaldehyde. The aerosol-forming substrates can contain 0.1 to 3 weight percent, 0.2 to 2.5 weight percent, or 0.3 to 2 weight percent tobacco. The concentration of formaldehyde in aerosols formed from such aerosol-forming substrates can be several times higher than the concentration of formaldehyde in aerosols of aerosol-generating articles that contain higher amounts of tobacco, such as more than 70 weight percent.

The nitrogen-containing nucleophilic compound may provide an aerosol with reduced amounts of aldehydes compared to an aerosol-forming substrate that does not contain the nitrogen-containing nucleophilic compound. Additionally, the nitrogen-containing nucleophilic compound may provide an aerosol that is free of aldehydes. Without being bound by any theory, the nitrogen-containing nucleophilic compound may either react with aldehydes in the aerosol or reduce or prevent the formation of aldehydes in the aerosol-forming substrate in situ. Thus, the nitrogen-containing nucleophilic compound may function as an aldehyde scavenger. Thus, any aerosol generated from the above-described aerosol-forming substrate may contain less aldehydes compared to an aerosol-forming substrate of the same composition, but lacking the nitrogen-containing nucleophilic compound.

Without being bound by any theory, nitrogen-containing nucleophilic compounds may react with aldehydes, particularly formaldehyde, present in the aerosol through the nitrogen atom. The compounds may be particularly nucleophilic due to the lone pair of electrons on the nitrogen atom.

The nitrogen-containing nucleophilic compound may contain groups such as * _-NH2 , *-NH-*, *-CN, _NH4 ⁺ , or *-C(=O)-NH-*, where the bond "*-" indicates attachment of the nitrogen-containing nucleophilic compound to a further moiety. Without being bound by any theory, these nitrogen atom-containing groups may react particularly well with any aldehydes, or chemical precursors of these aldehydes, that are formed upon heating of the aerosol-forming substrate.

According to another embodiment of the present invention, the nitrogen-containing nucleophilic compound may be one or both of an organic compound or an inorganic compound. In particular, the nitrogen-containing nucleophilic compound is
organic compounds which contain amino or amido groups (preferably amino groups), nitrogen-containing monosaccharides and polysaccharides or nitrogen-containing plastics,
- and inorganic ammonium compounds,
- or combinations thereof.

According to a further embodiment of the present invention, the nitrogen-containing nucleophilic compound is
- an amino acid selected from the group consisting of lysine, glycine, cysteine, arginine, or homocysteine, or a combination thereof;
- tripeptides containing glutathione,
urea or urea derivatives or combinations thereof,
- nitrogen-containing monosaccharides and polysaccharides selected from the group consisting of glucosamine, galactosamine, or chitosan, or combinations thereof;
- nitrogen-containing plastics selected from polyethylene-imine, polystyrene-acrylonitrile, or polyacrylonitrile butadiene-styrene, or combinations thereof.

These compounds may be particularly well suited to react with aldehydes. Thus, these compounds may reduce the concentration of aldehydes, particularly formaldehyde, in aerosols formed from these aerosol-forming substrates.

Compounds such as lysine, urea, chitosan, polyethylene-imine, and diammonium phosphate, or combinations thereof, may be particularly preferred.

The tripeptide containing glutathione is preferably glutathione.

The urea derivative may be selected from derivatives in which some or all of the hydrogen atoms of the _-NH2 group are replaced by either a _C1 - _C12 -alkyl group, an aryl group, a hydrogen group, or an alkyl-hydroxy group. Specific examples may be N-hydroxyureas, N-alkylureas, or N-arylureas, or any combination thereof.

The aerosol-forming substrate may contain 0.1 weight percent to 10 weight percent, 0.2 weight percent to 9 weight percent, preferably 0.5 weight percent to 8 weight percent, most preferably 1 weight percent to 5 weight percent, even more preferably 1 weight percent to 4 weight percent, or 1.5 weight percent to 3 weight percent of the nitrogen-containing nucleophilic compound on a dry weight basis based on the total amount of the aerosol-forming substrate. These weight percent ranges may be particularly advantageous for reducing the amount of aldehydes, especially formaldehyde, in the formed aerosol. A weight percent range of 2 weight percent to 4 weight percent may also be particularly preferred. Such a range may reduce or completely eliminate aldehydes in the formed aerosol.

The cellulose present in the aerosol-forming substrate of the present invention may function as a filler. In particular, the cellulose may function as a base material for an aerosol former that may be present in the aerosol-forming substrate. The cellulose may include particles having a size of less than 100 micrometers. The cellulose may be in powder form.

The cellulose may also include cellulose fibers. The cellulose fibers may have a length greater than 200 micrometers. The fiber length may vary from 200 to 2000 micrometers. The fiber width may vary from 14 to 32 micrometers. The cellulose fibers may act as an agent to strengthen the aerosol-forming substrate.

The cellulose derivatives may be derivatives in which the -OH groups of the D-glucose units of cellulose are at least partially or completely replaced by groups other than -OH groups. In preferred embodiments, the cellulose derivatives may be cellulose esters and cellulose ethers.

Typical cellulose esters may be cellulose acetate, cellulose propionate, or cellulose sulfate. Typical cellulose ethers may be cellulose ethers in which some or all of the hydrogen atoms of the -OH groups are replaced by alkyl groups, or carboxyalkyl groups. Suitable examples of the cellulose ether group may be methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, or carboxymethyl cellulose (CMC), or any combination thereof. Carboxymethyl cellulose may be particularly preferred. The cellulose derivative may function as a binder in the aerosol-forming substrate.

The cellulose and/or cellulose derivative may be present in an amount of 15 to 85 weight percent, preferably 20 to 80 weight percent, and more preferably 25 to 70 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate. These weight percent ranges may be particularly suitable for the cellulose and/or cellulose derivative to function as a binder or filler.

In particular, the cellulose may be present in an amount of 30 weight percent to 70 weight percent, preferably in an amount of 35 weight percent to 65 weight percent, more preferably in an amount of 30 weight percent to 58 weight percent, even more preferably in an amount of 40 weight percent to 60 weight percent, and most preferably in an amount of 40 weight percent to 50 weight percent. In particular, the cellulose may be present in an amount of 45 weight percent to 58 weight percent on a dry weight basis based on the total amount of the aerosol-forming substrate. These weight percent ranges are preferred for the cellulose, allowing it to function particularly well as a filler in the aerosol-forming substrate.

The cellulose derivative may be present in an amount of 1 weight percent to 15 weight percent, or 1.5 weight percent to 12 weight percent, preferably 2 weight percent to 10 weight percent, more preferably 2.5 weight percent to 8 weight percent, more preferably 3 weight percent to 5 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate.

The cellulose fibers may be present in an amount of 0.5 weight percent to 10 weight percent, preferably 1 weight percent to 8 weight percent, more preferably 2 weight percent to 6 weight percent, and most preferably 2.5 weight percent to 5.5 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate. These weight percent ranges allow the fibers to function particularly well as reinforcing agents for the aerosol-forming substrate.

In a further embodiment of the invention, one, two or all of the cellulose powder, cellulose fibres and cellulose derivatives may be present in the aerosol-forming substrate. For example, the aerosol-forming substrate may comprise a combination of cellulose powder and a cellulose derivative such as carboxymethylcellulose. Alternatively, the aerosol-forming substrate may comprise a combination of cellulose powder and cellulose fibres. In another alternative, the aerosol-forming substrate may comprise a combination of cellulose fibres cellulose derivatives. Furthermore, the aerosol-forming substrate may comprise only cellulose powder. The aerosol-forming substrate may also comprise only cellulose fibres or cellulose derivatives. In particular, cellulose powder, cellulose fibres and a cellulose derivative such as carboxymethylcellulose may be included in the aerosol-forming substrate. The presence of all three components may particularly well enable these components to function as reinforcing agents, fillers and binders.

The aerosol-forming substrate may include at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the aerosol generating system. Suitable aerosol formers may include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). The aerosol former may be a polyhydric alcohol or a mixture thereof (such as triethylene glycol, 1,3-butanediol, and glycerin). The aerosol former may be propylene glycol. The aerosol former may include both glycerin and propylene glycol. The aerosol former may include only glycerin.

The aerosol former may be present in an amount of 20 to 58 percent by weight, preferably 25 to 45 percent by weight, more preferably 30 to 38 percent by weight on a dry weight basis based on the total weight of the aerosol-forming substrate. The term "dry weight basis" refers throughout this application to the weight of the aerosol-forming substrate calculated after removing water via Karl Fischer titration, e.g., heating to a temperature of 110 degrees Celsius at standard conditions of temperature and pressure, and using potentiometry to determine the end point. The end point is detected by a bipotentiometric titration method. A second pair of Pt electrodes is immersed in the anodic solution. The detector circuit maintains a constant current between the two detector electrodes during the titration. Before the equivalence point, the solution contains ^I- but little _I2 . At the equivalence point, excess _I2 appears and a sharp voltage drop indicates the end point. The amount of charge required to generate _I2 and reach the end point can then be used to calculate the amount of water in the original sample. The aerosol former content can be measured by gas chromatography in combination with a flame ionization detector.

In some embodiments, the aerosol-forming substrate may further comprise a disaccharide. In a preferred embodiment, the aerosol-forming substrate may comprise a disaccharide. Without being bound by any theory, the disaccharide may function to facilitate the transfer of heat from an external heating element to the aerosol-forming substrate. Hence, when the aerosol-forming substrate is heated in a heating chamber by any external heating element, the disaccharide may assist in the reliable formation of an aerosol.

Furthermore, without being bound by any theory, the disaccharide may function to modify the release of the aerosol former during the course of different puffs taken by the user. For example, the presence of the disaccharide may allow the release of the aerosol former (e.g., glycerin) over a longer extended period of time. In particular, the user may even be able to enjoy the aerosol generated from the aerosol-forming substrate after taking six, seven, or eight or more puffs. Typically, the amount of aerosol generated during these subsequent puffs is reduced compared to the user's third or fourth puff.

The disaccharide may be selected from sucrose, lactose, or maltose, or a combination thereof. In a preferred embodiment, the disaccharide is sucrose.

The disaccharide may be present in an amount of 0.1 weight percent to 15 weight percent, preferably 0.5 weight percent to 12 weight percent, more preferably 1 weight percent to 10 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate. These weight percent ranges may allow the disaccharide to be particularly good at extending the release of the aerosol former during a puff taken by a user. Furthermore, these weight percent ranges may also be well suited for allowing the conduction of heat into the aerosol-forming substrate.

In some embodiments, the aerosol-forming substrate may further comprise nicotine. The nicotine may form a significant portion of the aerosol generated from the aerosol-forming substrate upon heating.

The aerosol-forming substrate may contain nicotine in an amount of 0.1 weight percent to 10 weight percent, preferably 0.5 weight percent to 8 weight percent, more preferably 1 weight percent to 3 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate. The "dry weight" nicotine content can also be detected by gas chromatography combined with a flame ionization detector.

The aerosol-forming substrate may additionally comprise at least one carboxylic acid, preferably a _C3 - _C6 alkyl hydroxy carboxylic acid, an alkyl keto carboxylic acid, or an aryl carboxylic acid. The at least one carboxylic acid may protonate any nicotine present in the aerosol-forming substrate. Specific examples of carboxylic acids may be lactic acid, benzoic acid, citric acid, malic acid, tartaric acid, 2-methylbutyric acid, levulinic acid, or any combination thereof. Preferably, nicotine is protonated with an acid in solution to produce a nicotinic acid salt. The nicotinic acid salt may then be employed with other components, such as cellulose or cellulose derivatives, to generate the aerosol-forming substrate. For example, nicotine may be used as a 10 weight percent solution in glycerin, and two molar equivalents of lactic acid may be added and mixed into a slurry of the remaining components. The one or more protonated nicotine salts may have a higher water solubility compared to the base without nicotine. Preferably, the one or more nicotine salts may be selected from the list consisting of nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine pectinate, nicotine alginate, and nicotine salicylate. These salt forms of nicotine are more stable than the typically used liquid free base nicotine. Hence, an aerosol-forming substrate comprising one or more of these nicotine salts may have a longer shelf life than a typical aerosol-forming substrate.

The at least one carboxylic acid may be present in an amount of 0.1 weight percent to 10 weight percent, preferably 0.5 weight percent to 8 weight percent, and more preferably 1 weight percent to 3 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate.

The aerosol-forming substrate may include non-tobacco volatile flavor compounds. These non-tobacco volatile flavor compounds may form an aerosol with the aerosol former upon heating of the aerosol-forming substrate. For example, the non-tobacco volatile flavor compounds may include menthol. The term "menthol" as used herein means the compound 2-isopropyl-5-methylcyclohexanol in any of its isomeric forms. The non-tobacco volatile flavor compounds may provide a flavor selected from the group consisting of menthol, lemon, vanilla, orange, wintergreen, cherry, and cinnamon.

The amount of non-tobacco volatile flavor compounds in the aerosol-forming substrate may be from 0.1 weight percent to 54 weight percent, preferably from 0.5 weight percent to 30 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate.

According to a further embodiment of the invention, the aerosol-forming substrate may comprise between 0.1 and 3 percent by weight of tobacco, preferably between 0.1 and 2 percent by weight of tobacco.

According to a further embodiment of the invention, the aerosol-forming substrate is substantially free of tobacco, more preferably free of any tobacco. In this case, the aerosol may be formed by the aerosol former and one or both of the nicotine and non-tobacco volatile flavour compounds (if present). The tobacco flavour compounds may contribute substantially or not at all to the formation of the aerosol when the aerosol-forming substrate is heated.

The cellulose and/or cellulose derivatives may also be derived from cellulose sources other than tobacco. For example, trees or non-tobacco plants may serve as sources for the cellulosic material. Thus, the cellulose and/or cellulose derivatives may not be derived from tobacco.

The presence or absence of tobacco within an aerosol-forming substrate can also be clearly identified by DNA barcoding. Methods for performing DNA barcoding based on the nuclear genes ITS2 (internal transcribed spacer 2), rbcL, and matK system of tobacco as well as the plastid intergenic spacer trnH-psbA are well known in the art and can be used (Chen S, Yao H, Han J, Liu C, Song J, et al. (2010) Validation of the ITS2 Region as a Novel DNA Barcode for Identifying Medicinal Plant Species. PLoSONE 5(1):e8613; Hollingsworth PM, Graham SW, Little DP (2011) Choosing and Using a Plant DNA Barcode. PLoS ONE 6(5):e19254).

The substrate portion including the aerosol-forming substrate may be formed as a sheet (preferably a cast sheet). The sheet of aerosol former may be formed by a casting process of the type that generally involves casting a slurry including one or both of cellulose and cellulose derivatives (and optionally the aerosol former and the nitrogen-containing nucleophilic compound) onto a conveyor belt or other support surface, drying the cast slurry to form a sheet of aerosol-forming substrate, and removing the sheet of aerosol-forming substrate from the support surface. For example, in certain embodiments, a sheet of aerosol-forming substrate for use in the present invention may be formed by a casting process from a slurry including cellulose, cellulose fibers, carboxymethylcellulose, and optionally glycerin. Additionally, the slurry may include an additional component selected from nicotine, nicotine salts, and disaccharides.

In one embodiment, a slurry is formed that includes at least one of cellulose and cellulose derivatives, an aerosol former, a nitrogen-containing nucleophilic compound, and tobacco, if present. The components in the slurry may have a concentration of 15 weight percent to 25 weight percent, preferably 20 weight percent, on a dry weight basis. A cast sheet may be formed from the slurry. The cast sheet may be formed by drying. The target sheet thickness may be 200 micrometers to 300 micrometers, preferably 250 micrometers. The sheet weight may be 160 to 180 grams per square meter.

Alternatively, the casting process to form the sheet of non-tobacco material may employ only one or both of the cellulose and cellulose derivatives. The cast sheet may then serve as a cellulose absorbing substrate for absorbing one or both of the nicotine (preferably a nicotine salt) and the aerosol former onto the sheet. Additionally, one or both of the nitrogen-containing nucleophilic compound and the disaccharide may also be absorbed onto the absorbing substrate or may be present during the casting process.

The nicotine (preferably a nicotine salt) and the aerosol former may be combined with water as a liquid formulation. The liquid formulation may further include any of the non-tobacco volatile flavor compounds described above. Such a liquid formulation may then be absorbed by an absorbent substrate or coated onto the surface of an absorbent substrate.

The substrate portion including the aerosol-forming substrate may be formed as a rod. The substrate portion may be provided with an assembly of sheets of non-tobacco material formed by the casting process described above, including at least one or both of cellulose and cellulose derivatives. The substrate portion may be surrounded by a wrapper. The sheets of non-tobacco material may be textured or crimped and may include an absorbent substrate, a nicotine salt, and an aerosol former. The assembly of sheets of non-tobacco material preferably extends along substantially the entire length of the substrate portion and across substantially the entire transverse cross-sectional area of the substrate portion. The sheets may further include water.

The aerosol-forming substrate may comprise up to 5 weight percent tobacco on a dry weight basis based on the total amount of the aerosol-forming substrate. The tobacco may comprise cast leaf tobacco, reconstituted tobacco, tobacco paper, tobacco powder, blended tobacco, strips, sheets, shredded tobacco, or any other suitable form of tobacco. The tobacco may be produced from a sheet of tobacco material homogenized by a reconstitution process. These processes include, but are not limited to, a papermaking process of the type described, for example, in U.S. Pat. No. 3,860,012, or a casting or "cast leaf" process of the type described, for example, in U.S. Pat. No. 5,724,998. For example, in certain embodiments, a homogenized sheet containing tobacco material for use in the present invention may be formed from a slurry that additionally comprises particulate tobacco in addition to the other components for the slurry described above.

As used herein, the term "assembled" may mean that the sheet of aerosol-forming substrate is rolled, folded, or otherwise compressed or clamped substantially transversely to the cylindrical axis of the rod.

The term "sheet" may refer to a layered element having a width and length substantially greater than its thickness.

Another embodiment of the present invention is directed to an aerosol-generating article comprising a substrate portion containing an aerosol-forming substrate as described herein. Preferably, the substrate portion in the article may be in the form of a rod.

The aerosol-generating article may further comprise a connecting portion. The connecting portion may preferably have a tubular hollow core. Such a tubular hollow core may be located downstream of the substrate portion and may abut the aerosol-forming substrate.

The connecting portion may be formed from any suitable material or combination of materials. For example, the connecting portion may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the connecting portion may be formed from cellulose acetate, preferably a hollow cellulose acetate tube.

It is preferable that the connecting portion has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

The aerosol-generating article may further comprise tipping paper disposed at least partially wrapped around the connecting portion and the base portion so as to overlap the connecting portion and the base portion. Such tipping paper may increase the stability of the aerosol-generating article.

A further aspect of the present invention is directed to an aerosol generating system comprising an aerosol generating article as described herein and an aerosol generating device. The aerosol generating device may comprise a heating element and a heating chamber for receiving the aerosol generating article. The heating element may be configured to heat the aerosol generating article to a temperature in the range of 220 degrees Celsius to 400 degrees Celsius, preferably 250 degrees Celsius to 290 degrees Celsius. At these temperatures, an aerosol may be generated from an aerosol-forming substrate contained within the aerosol generating article. The aerosol may be aldehyde-reduced due to the presence of nitrogen-containing nucleophilic compounds.

The aerosol generating device may heat, but not combust, the aerosol-generating article. Such electrically heated, non-combustion heated aerosol generating systems heat the aerosol-generating article to a temperature sufficient to produce an aerosol from a substrate without combusting the substrate.

As used herein, the terms "upstream" and "downstream" are used to describe the relative locations of components or portions of components of the aerosol generating device and the aerosol generating article with respect to the direction in which a user draws on an aerosol generating article inserted into the heating chamber of the aerosol generating device during use.

The aerosol generating article may have a mouth end through which, in use, the aerosol exits the aerosol generating system and is delivered to the user. The mouth end may be referred to as the downstream end. In use, a user sucks on the downstream or mouth end of the aerosol generating system (particularly the aerosol generating article) to inhale the aerosol generated by the aerosol generating system. The aerosol generating system has an upstream end opposite the downstream or mouth end.

In some aspects of the present disclosure, the heating element may include an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide, etc.), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold, and silver. Examples of suitable metal alloys include stainless steel, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, gold-containing, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, and iron-manganese-aluminum-based alloys. In composite materials, the electrically resistive material may be optionally embedded in, encapsulated in, or coated with the insulating material, or vice versa, depending on the required energy transfer kinetics and external physicochemical properties.

In another embodiment, a heated aerosol-generating article may be used with a combustible heat source and an aerosol-generating substrate downstream of the combustible heat source. For example, an aerosol-generating article having an aerosol-generating substrate in a heated aerosol-generating article of the type disclosed in WO-A-2009/022232 may be employed, 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. However, it will be appreciated that the aerosol-generating article as described herein may also be used in heated aerosol-generating articles with combustible heat sources having other configurations.

As noted, in any of the aspects of the present disclosure, the heating element may be part of the aerosol generating device. The aerosol generating device may include an internal heating element, or an external heating element, or both an internal heating element and an external heating element, where "internal" and "external" are with respect to the aerosol generating article. The internal heating element may take any suitable form. For example, the internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different conductive portions or an electrically resistive metal tube. Alternatively, the internal heating element may be one or more heating needles or rods that pass through the center of the substrate portion of the aerosol generating article. Other alternatives include heating wires or filaments, such as Ni-Cr (nickel chromium), platinum, tungsten, or alloy wires or heating plates. Optionally, the internal heating element may be disposed in or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal that has a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as a ceramic material, and then sandwiched in another insulating material, such as glass. A heater formed in this manner may be used to both heat the heating element and monitor its temperature during operation.

The external heating element may take any suitable form. For example, the external heating element may take the form of one or more flexible heating foils on a dielectric substrate such as polyimide. The flexible heating foils may be shaped to fit the periphery of a heating chamber for receiving the aerosol-generating article. Alternatively, the external heating element may take the form of a metal grid(s), a flexible printed circuit board, a molded integrated circuit component (MID), a ceramic heater, a flexible carbon fiber heater, or may be formed using a coating technique such as plasma deposition on a substrate of suitable shape. The external heating element may also be formed using a metal that has a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating material. An external heating element formed in this manner may be used both to heat the external heating element and to monitor the temperature of the external heating element during operation.

The internal or external heating element may comprise a heat sink or heat store, which includes a material capable of absorbing and storing heat and then releasing the heat over time to the substrate portion of the aerosol-generating article. The heat sink may be formed of any suitable material, such as a suitable metal or ceramic material. In one embodiment, the material is a material that has a high heat capacity (sensible heat storage material) or has the ability to absorb heat and then release it by a reversible process (such as a high temperature phase change). Suitable sensible heat storage materials include silica gel, alumina, carbon, glass mat, glass fiber, minerals, metals or alloys (such as aluminum, silver, or lead), and cellulosic materials (such as paper). Other suitable materials that release heat by a reversible phase change include paraffin, sodium acetate, naphthalene, wax, polyethylene oxide, metals, metal salts, mixtures of eutectic salts, or alloys. The heat sink or heat store may be disposed in direct contact with the substrate portion of the aerosol-generating article and capable of transferring the stored heat directly to the substrate. Alternatively, the heat stored in the heat sink or heat reservoir may be transferred to the base portion of the aerosol-generating article by a thermal conductor such as a metal tube.

As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. Generally, the susceptor is a material capable of absorbing electromagnetic energy and converting it into heat. When located in an alternating electromagnetic field, eddy currents are typically induced in the susceptor and hysteresis losses occur, causing the susceptor to heat up. The changing electromagnetic field generated by one or several induction coils heats the susceptor, which then transfers heat to the aerosol-generating article so that the aerosol is formed. The heat transfer may be primarily by thermal conduction. Such heat transfer is best when the susceptor is in intimate thermal contact with the aerosol-generating article.

The susceptor may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. A preferred susceptor may include or consist of a ferromagnetic material (e.g., a ferromagnetic alloy, ferritic iron, or ferromagnetic steel or stainless steel). A suitable susceptor may be or include aluminum. A preferred susceptor may be heated to a temperature in excess of 250 degrees Celsius.

The preferred susceptor is a metallic susceptor (e.g., stainless steel). However, the susceptor material may also include or be made of graphite, molybdenum, silicon carbide, aluminum, niobium, Inconel alloys (austenitic nickel-chromium based superalloys), metal-deposited films, ceramics (e.g., zirconia, etc.), transition metals (e.g., iron, cobalt, nickel, etc.), or semi-metallic components (e.g., boron, carbon, silicon, phosphorus, aluminum, etc.).

The susceptor material is preferably a metallic susceptor material. The susceptor may also be a multi-material susceptor and may include a first susceptor material and a second susceptor material. In some embodiments, the first susceptor material may be disposed in close physical contact with the second susceptor material. The second susceptor material preferably has a Curie temperature lower than the ignition point of the aerosol-forming substrate. The first susceptor material is preferably used primarily to heat the susceptor when it is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum or an iron-based material such as stainless steel. The second susceptor material is preferably used primarily to indicate when the susceptor has reached a particular temperature (a temperature that is the Curie temperature of the second susceptor material). The Curie temperature of the second susceptor material may be used to regulate the temperature of the entire susceptor during operation. Suitable materials for the second susceptor material may include nickel and certain nickel alloys.

By providing a susceptor having at least a first and a second susceptor material, the heating of the aerosol-forming substrate and the temperature control of the heating can be separate. The second susceptor material is preferably a magnetic material having a second Curie temperature that is substantially the same as the desired maximum heating temperature. That is, the second Curie temperature is preferably approximately the same as the temperature to which the susceptor should be heated to generate an aerosol from the aerosol-forming substrate.

When an induction heating element is employed, the induction heating element may be configured as an internal heating element as described herein, or as an external heater as described herein. When the induction heating element is configured as an internal heating element, the susceptor element is preferably configured as a pin or blade for penetrating the aerosol-generating article. When the induction heating element is configured as an external heating element, the susceptor element is preferably configured as a cylindrical susceptor that at least partially surrounds or forms a sidewall of the heating chamber.

The heating element may heat the substrate portion of the aerosol-generating article by conduction. The heating element may be in at least partial contact with the substrate or at least partial contact with a carrier on which the substrate is deposited. Alternatively, heat from either an internal or external heating element may be conducted to the substrate by a thermally conductive element.

During operation, the aerosol-generating article may be completely contained within the aerosol-generating device, in which case the user may inhale on the mouthpiece of the aerosol-generating device. Alternatively, during operation, only the substrate portion of the aerosol-generating article may be contained within the aerosol-generating device, in which case the user may inhale directly on the aerosol-generating article.

The aerosol generating device may comprise an electrical circuit. The electrical circuit may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of the controller. The electrical circuit may comprise further electronic components. The electrical circuit may be configured to regulate the supply of power to the heating element. Power may be supplied to the heating element continuously following activation of the aerosol generating device or may be supplied intermittently (e.g. after each puff). Power may be supplied to the heating element in the form of current pulses. The electrical circuit may be configured to monitor the electrical resistance of the heating element and may be configured to control the supply of power to the heating element, preferably depending on the electrical resistance of the heating element.

The aerosol generating device may include a power source (typically a battery) within the main body of the aerosol generating device. In one embodiment, the power source is a lithium ion battery. Alternatively, the power source may be a nickel metal hydride battery, a nickel cadmium battery, or a lithium-based battery (e.g., a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery). Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for storage of sufficient energy for one or more use experiences. For example, the power source may have a capacity sufficient to continuously generate aerosol for about six minutes, or a multiple of six minutes. In another example, the power source may have a capacity sufficient to provide a predetermined number of puffs, or discontinuous activation of the heating element.

Another aspect of the present invention is a method of operating an aerosol generating system as described herein, comprising the steps of:
A) inserting the aerosol-generating article into a heating chamber;
and B) heating the aerosol-generating article with a heating element, thereby generating an aerosol and allowing the aldehyde to react with the nitrogen-containing nucleophilic compound to provide an aldehyde-reduced aerosol.

Upon heating the aerosol-generating article, an aerosol that is substantially free or completely free of aldehydes may be provided.

During heating of the aerosol-generating article, formaldehyde may be formed as an aldehyde, which reacts with the nitrogen-containing nucleophilic compound to provide a formaldehyde-reduced aerosol. Formaldehyde may be one of the primary aldehydes formed during generation of aerosol from the aerosol-forming substrate of the present invention.

Aerosol-generating articles including an aerosol-forming substrate according to any embodiment of the present invention may preferably include one or both of urea and lysine as the nitrogen-containing nucleophilic compound within the aerosol-forming substrate.

A further aspect of the present invention is also directed to the use of a nitrogen-containing nucleophilic compound to remove aldehydes from an aerosol formed by heating an aerosol-generating article as described herein.

During use of the nitrogen-containing nucleophilic compound, the aerosol may be heated to a temperature of 220 degrees Celsius to 400 degrees Celsius, preferably 250 degrees Celsius to 290 degrees Celsius.

Features described with respect to one embodiment may equally be applied to other embodiments of the invention.

The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 shows a bar graph of the formaldehyde content of different aerosol-generating articles containing tobacco as well as non-tobacco aerosol-forming substrates. FIG. 2 illustrates a bar graph of the formaldehyde content of different aerosol-generating articles containing different concentrations of urea. FIG. 3 shows a bar graph of the formaldehyde content of different aerosol-generating articles, including tobacco or other non-tobacco aerosol-forming substrates with sucrose and lysine. FIG. 4 shows the release of the aerosol former glycerin during 12 puffs taken by a user depending on the amount of the disaccharide sucrose in the aerosol-forming substrate. FIG. 5 illustrates a schematic diagram of an aerosol generating system comprising an aerosol generating device and an aerosol generating article.

Figure 1 illustrates a bar graph of the amount of formaldehyde detected in the aerosol generated from various aerosol-generating articles having a heating element at a temperature of 350 degrees Celsius. The substrate portion containing the aerosol-forming substrate of the aerosol-generating article was heated by an internal blade. In general, formaldehyde in smoke can be detected by trapping the aerosol in a DNPH derivatization solution (2,4-dinitrophenylhydrazine) using a smoking machine. Pyridine is added to quench the derivatization reaction up to 15 minutes after the end of aerosol collection. A solution containing an internal standard is added to the stabilized aerosol extract, which is then analyzed using ultra-performance liquid chromatography with MS-MS detection and an ESI (electrospray ionization) source in negative mode. In this figure, as well as in Figures 2 and 3, the vertical axis indicates the amount of formaldehyde detected in micrograms per aerosol-generating article. The bar labeled 10 shows that 3.7 micrograms of formaldehyde were detected in the aerosol of the aerosol-generating article containing 75 weight percent tobacco blend, 18 weight percent glycerin as an aerosol former, and the remainder binder. In contrast to the tobacco-containing aerosol-generating article, 15.4 micrograms of formaldehyde were detectable in the aerosol of the aerosol-generating article containing 45 weight percent cellulose, 30 weight percent inositol, 20 weight percent glycerin, and the remainder binder (bar labeled 12). Inositol functions as a plasticizer. The data show that up to four times more formaldehyde is released from the non-tobacco-containing aerosol-forming substrate compared to the substrate containing tobacco. The bars labeled 14 and 16 show that no formaldehyde was detectable in the aerosol of an aerosol-generating article containing 45 weight percent cellulose, 26.25 weight percent inositol, 20 weight percent glycerin, and either 3.75 weight percent urea (bar labeled 14) or 3.75 weight percent lysine (bar labeled 16). Thus, both urea and lysine act as nitrogen-containing nucleophilic compounds that react with formaldehyde, thereby removing it from the aerosol.

2 illustrates bar graphs of formaldehyde detected in aerosols generated from various aerosol-generating articles having a heating element at a temperature of 350 degrees Celsius. The bar labeled 18 indicates that 3.5 micrograms of formaldehyde could be detected in the aerosol formed from the aerosol-generating article containing 75 weight percent tobacco blend, 18 weight percent glycerin, and the remainder binder. 2.11 micrograms of formaldehyde were contained in the aerosol of the aerosol-generating article containing 56 weight percent cellulose, 5 weight percent carboxymethylcellulose, 1 weight percent urea, 3 weight percent cellulose fiber, and 35 weight percent glycerin (bar labeled 20). Therefore, the amount of formaldehyde in the aerosol could be reduced by 39 percent when including 1 weight percent urea as a formaldehyde scavenger. No formaldehyde was detectable in the aerosol of an aerosol-generating article containing 49 weight percent cellulose, 8 weight percent carboxymethylcellulose, 5 weight percent urea, 3 weight percent cellulose fiber, and 35 weight percent glycerin (bar labeled 22).

3 shows a bar graph of formaldehyde detected in the aerosol of various aerosol-generating articles having different compositions. At 350 degrees Celsius, 3.31 micrograms of formaldehyde were detectable in the aerosol-generating article containing 75 weight percent tobacco blend and other components as described above for FIG. 2 (bar labeled 24). An aerosol-generating article containing 58 weight percent cellulose, 35 weight percent glycerin, 4 weight percent carboxymethylcellulose, and 3 weight percent cellulose fiber generated 1.68 micrograms of formaldehyde (bar labeled 26). In contrast, more formaldehyde was detected in the aerosol of an aerosol-generating article in which 10 weight percent cellulose was replaced with 10 weight percent sucrose (bar labeled 28), suggesting that the presence of sucrose, a disaccharide, increases the amount of formaldehyde. The emission of formaldehyde associated with disaccharides can be reliably reduced or prevented by including the nitrogen-containing nucleophilic compound of the present invention in the aerosol-forming substrate. The bar graph labeled 30 shows that no formaldehyde was detectable in the aerosol of an aerosol-generating article containing 56 weight percent cellulose, 35 weight percent glycerin, 2 weight percent lysine as the nitrogen-containing nucleophilic compound, 4 weight percent carboxymethylcellulose, and 3 weight percent cellulose fiber.

Similar results (not shown) were achieved when aerosol-generating articles weighing 0.5 grams and having an aerosol-forming substrate containing 42 weight percent cellulose, 28 weight percent sorbitol, 20 weight percent glycerin, 5 weight percent ammonium phosphate, 5 weight percent chitosan, 5 weight percent lysine, 5 weight percent urea, or 5 weight percent polyethyleneimine, with the remainder being cellulose fibers and guar gum, were heated to 350 degrees Celsius for 6 minutes. In all these cases, no formaldehyde was detectable by TG-GC-MS analysis.

FIG. 4 shows a graph in which the vertical axis illustrates the amount of glycerin per puff (micrograms/puff) detected by FT-IR and the horizontal axis illustrates the number of puffs. The graph illustrates the amount of glycerol detected in the aerosol during 12 consecutive puffs at a heating element temperature of 250 degrees Celsius. For comparison, the graph labeled 32 illustrates the amount of glycerin released from a tobacco-containing aerosol-generating article containing 75 weight percent tobacco, 18 weight percent glycerin, and the remainder binder. The graph labeled 34 illustrates the release of glycerin from an aerosol-generating article containing 58 weight percent cellulose, 35 weight percent glycerin, 4 weight percent carboxymethylcellulose, and 3 weight percent cellulose fiber. Further graphs show the release of glycerin from aerosol-generating articles in which 10 weight percent of the cellulose has been replaced by 10 weight percent of sucrose (graph labeled 36) or 20 weight percent of the cellulose has been replaced by 20 weight percent of sucrose (graph labeled 38). It can be clearly seen that the addition of sucrose results in a delay in the release of glycerin, such that more glycerin is released at a later stage, starting at puff number 7 or 8.

5 illustrates a schematic diagram of an aerosol generating system comprising an aerosol generating device 46 and an aerosol generating article 40. The aerosol generating article 40 comprises a base portion 42 and a connecting portion 44. The base portion 42 comprises the aerosol-forming substrate of the present invention and is located upstream in the direction of the aerosol generating article. The downstream connecting portion 44 may comprise a tubular hollow portion, such as a hollow acetate tube. The aerosol generating article 40 can be inserted into the heating chamber 48 of the aerosol generating device 46 in such a way that the base portion 42 is next to the heating element 50 of the heating chamber. Additional elements, such as a circuit 52 (such as a microprocessor) and a power source 54 (such as a battery), are present in the aerosol generating device 46. The power source and the circuit as well as the heating element can be electrically connected via an electrical connection 56. During use of the aerosol generating device, a user may suck on the downstream end of the aerosol-generating article 40, which may be the connecting portion 44 or an additional mouthpiece or filter (not shown in FIG. 5), to inhale the aerosol formed during heating of the substrate portion 42. The aerosol may contain reduced concentrations of aldehydes due to the presence of nitrogen-containing nucleophilic compounds in the aerosol-forming substrate of the substrate portion 42.

Claims (15)

1. An aerosol-forming substrate comprising:
a) one or both of cellulose and cellulose derivatives,
b) an aerosol former; and
c) from 0 to 5 weight percent, preferably from 0 to 3 weight percent, more preferably from 0 to 1 weight percent, and most preferably from 0 to 0.5 weight percent tobacco on a dry weight basis based on the total amount of the aerosol-forming substrate;
d) a nitrogen-containing nucleophilic compound; and
e) a disaccharide. The nitrogen-containing nucleophilic compound is one or both of an organic compound and an inorganic compound, and preferably
organic compounds which contain amino or amide groups (preferably amino acids), nitrogen-containing monosaccharides and polysaccharides or nitrogen-containing plastics,
- inorganic ammonium compounds,
-or combinations thereof. The nitrogen-containing nucleophilic compound is
- an amino acid selected from the group consisting of lysine, glycine, cysteine, arginine, or homocysteine, or a combination thereof;
- tripeptides containing glutathione,
urea or urea derivatives or combinations thereof,
- nitrogen-containing monosaccharides and polysaccharides selected from the group consisting of glucosamine, galactosamine, or chitosan, or combinations thereof;
inorganic ammonium compounds selected from ammonium phosphates and metal ammonium phosphates (in particular diammonium phosphate, triammonium phosphate, ammonium hydrogen phosphate or ammonium dihydrogen phosphate), or alkaline earth metal ammonium phosphates, or combinations thereof,
3. The aerosol-forming substrate according to claim 1 or 2, which is selected from at least one of the following nitrogen-containing plastics: polyethylene-imine, polystyrene-acrylonitrile, or polyacrylonitrile butadiene-styrene, or combinations thereof. The aerosol-forming substrate according to any one of claims 1 to 3, comprising a disaccharide selected from sucrose, lactose, or maltose, or a combination thereof, preferably sucrose. The aerosol-forming substrate according to any one of claims 1 to 4, which is substantially free of tobacco, more preferably free of tobacco. The aerosol-forming substrate according to any one of claims 1 to 5, wherein one or both of the cellulose and cellulose derivatives are selected from cellulose, cellulose esters, or cellulose ethers, or combinations thereof, in particular cellulose acetate or carboxymethylcellulose. The aerosol-forming substrate according to any one of claims 1 to 6, wherein the aerosol former is selected from a polyhydric alcohol, an ester of a polyhydric alcohol, or an aliphatic ester of a monocarboxylic acid, dicarboxylic acid, or polycarboxylic acid, or a combination thereof. The aerosol-forming substrate according to any one of claims 1 to 7, further comprising nicotine as component f). The aerosol-forming substrate according to any one of claims 1 to 8, formed as a sheet (preferably a cast sheet). The aerosol-forming substrate according to any one of claims 1 to 9, wherein one or both of the cellulose and cellulose derivative of component a) are present in an amount of 15 to 85 weight percent, preferably 20 to 80 weight percent, more preferably 25 to 70 weight percent, on a dry weight basis based on the total amount of the aerosol-forming substrate. An aerosol-generating article comprising a substrate portion containing the aerosol-forming substrate according to any one of claims 1 to 10, preferably the substrate portion within the article being in the form of a rod. An aerosol generating system comprising an aerosol generating device and the aerosol generating article according to claim 11, wherein the aerosol generating device comprises a heating element and a heating chamber for receiving the aerosol generating article, the heating element being configured to heat the article to a temperature preferably in the range of 220 degrees Celsius to 400 degrees Celsius, preferably 250 degrees Celsius to 290 degrees Celsius. 13. A method of operating an aerosol generating system according to claim 12, comprising the steps of:
A) inserting the aerosol-generating article into the heating chamber;
B) heating the aerosol-generating article with the heating element, thereby generating an aerosol and an aldehyde, which reacts with the nitrogen-containing nucleophilic compound to provide an aldehyde-reduced aerosol. Use of a nitrogen-containing nucleophilic compound to provide an aldehyde-reduced aerosol formed by heating the aerosol-generating article of claim 11. The use of claim 14, wherein the aerosol-generating article is heated to a temperature of from 220 degrees Celsius to 400 degrees Celsius, preferably from 250 degrees Celsius to 290 degrees Celsius.

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