WO2024175464A1

WO2024175464A1 - Aerosol-generating article with aerosol-forming wrapper

Info

Publication number: WO2024175464A1
Application number: PCT/EP2024/053858
Authority: WO
Inventors: Attila Lukacs
Original assignee: Philip Morris Products S.A.
Priority date: 2023-02-21
Filing date: 2024-02-15
Publication date: 2024-08-29

Abstract

The invention relates to an aerosol-generating article. The aerosol-generating article comprises an aerosol-forming substrate portion comprising a primary aerosol-forming substrate. The aerosol-generating article comprises a substrate wrapper. The substrate wrapper surrounds at least a part of the aerosol-forming substrate portion. The substrate wrapper comprises a secondary aerosol-forming substrate. One or both of the primary and secondary aerosol-forming substrates comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. The invention further relates to an aerosol-generating system comprising an aerosol-generating article and an aerosol- generating device.

Description

AEROSOL-GENERATING ARTICLE WITH AEROSOL-FORMING WRAPPER

The present disclosure relates to an aerosol-generating article. The present disclosure further relates to an aerosol-generating system.

It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat an aerosol-forming substrate contained in an aerosol-generating article without burning the aerosol-forming substrate. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a heating chamber of the aerosol-generating device.

The aerosol-generating device may comprise a heating arrangement. The heating arrangement may be an induction heating arrangement and may comprise an induction coil configured to inductively heat a susceptor. The susceptor may be part of the device or may be part of the aerosol-generating article.

It would be desirable to provide an aerosol-generating article that allows for more efficient aerosol generation. It would be desirable to provide an aerosol-generating article with more constant flavor delivery. It would be desirable to provide an aerosol-generating article with improved flavor delivery within the initial one or more puffs. It would be desirable to provide an aerosol-generating article with improved user experience. It would be desirable to provide an aerosol-generating article with a simplified construction. It would be desirable to provide an aerosol-generating article which enables additional possibilities to adjust aerosol delivery. It would be desirable to provide an aerosol-generating article with a prolonged shelf life. It would be desirable to provide an aerosol-generating article which can be used with existing aerosol-generating devices. It would be desirable to provide a more energy efficient aerosol-generating system.

According to an embodiment of the invention there is provided an aerosol-generating article. The aerosol-generating article may comprise an aerosol-forming substrate portion. The aerosol-forming substrate portion may comprise a primary aerosol-forming substrate. The aerosol-generating article may comprise a substrate wrapper. The substrate wrapper may surround at least a part of the aerosol-forming substrate portion. The substrate wrapper may comprise a secondary aerosol-forming substrate. One or both of the primary and secondary aerosol-forming substrates may comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. One or both of the primary and secondary aerosol-forming substrates may comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

According to an embodiment of the invention there is provided an aerosol-generating article. The aerosol-generating article comprises an aerosol-forming substrate portion. The aerosol-forming substrate portion comprises a primary aerosol-forming substrate. The aerosol-generating article comprises a substrate wrapper. The substrate wrapper surrounds at least a part of the aerosol-forming substrate portion. The substrate wrapper comprises a secondary aerosol-forming substrate. One or both of the primary and secondary aerosolforming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

By the substrate wrapper comprising a secondary aerosol-forming substrate, an aerosol-generating article which enables additional possibilities to adjust aerosol delivery may be provided. An aerosol-generating article that may allow for more efficient aerosol generation is provided. An aerosol-generating article that may allow for more constant flavor delivery is provided. An aerosol-generating article that may allow for improved flavor delivery within the initial one or more puffs is provided. An aerosol-generating article that may allow for an improved user experience is provided. An aerosol-generating article with a simplified construction may be provided. An aerosol-generating article which can be used with existing aerosol-generating devices may be provided. A more energy efficient aerosol-generating system may be provided.

For example, the temperatures to be reached in an aerosol-generating article may be much lower than in conventional combustible cigarettes. Also, particularly during the first puffs, the aerosol-generating article may still heat up. An aerosol former, like glycerin, may not be sufficiently aerosolized due to the lowered temperatures, particularly during the first one or more puffs. By the substrate wrapper of the invention, a wrapper that can be aerosolized at lower temperatures and during the first one or more puffs may be provided. A more constant flavor delivery may be provided. An improved flavor delivery within the initial one or more puffs may be provided. An improved user experience may be provided. A more energy efficient aerosol-generating system may be provided.

It has been surprisingly found that inclusion of one or more carboxylic acids in one or both of the primary and secondary aerosol-forming substrates may advantageously improve the stability of nicotine in the aerosol-forming substrate during storage of aerosol-generating articles according to the invention. An aerosol-generating article with a prolonged shelf life may be provided.

The one or more cellulose based agents in one or both of the primary and secondary aerosol-forming substrates may advantageously provide additional strength to the aerosolforming substrate. This may improve the mechanical stability of the aerosol-forming substrate. A self-supporting aerosol-forming substrate, for example a self-supporting solid aerosol-forming film, may thus be provided. An additional support may advantageously not be needed and may be omitted. A robust aerosol-generating article without an additional support for one or both of the primary and secondary aerosol-forming substrates may be provided.

The primary aerosol-forming substrate may comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. The secondary aerosol-forming substrate may comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. The primary aerosol-forming substrate and the secondary aerosol-forming substrate may each comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

The primary aerosol-forming substrate may comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. The secondary aerosol-forming substrate may comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids. The primary aerosolforming substrate and the secondary aerosol-forming substrate may each comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

The primary and secondary aerosol-forming substrates may both have the same composition. By using the same material for the aerosol-forming substrate portion and the surrounding wrapper, a simplified construction may be provided.

The primary and secondary aerosol-forming substrates may have different compositions. In some embodiments, only the secondary aerosol-forming substrate comprises one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

One or both of the primary and secondary aerosol-forming substrates comprises nicotine. One or both of the primary and secondary aerosol-forming substrates may comprise a total nicotine content on a dry weight basis of between 0.1 percent by weight and 6 percent by weight, more preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.0 percent by weight and 2.0 percent by weight, more preferably between 1.2 percent by weight and 1.8 percent by weight.

One or both of the primary and secondary aerosol-forming substrates may comprise a total aerosol former content on a dry weight basis of at least 30 percent by weight, more preferably at least 35 percent by weight, more preferably at least 40 percent by weight, more preferably at least 45 percent by weight, more preferably at least 50 percent by weight. The aerosol former may comprise or may consist of glycerin.

One or both of the primary and secondary aerosol-forming substrates may comprise a total carboxylic acid content on a dry weight basis of between 0.1 percent by weight and 6 percent by weight, preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.0 percent by weight and 2.5 percent by weight, more preferably between 1.4 percent by weight and 2.0 percent by weight.

The one or more carboxylic acids may be selected from lactic acid, levulinic acid, acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

Optionally, the one or more carboxylic acids:

(i) do not contain any non-carboxyl alkyl hydroxyl groups and do not contain any ketone groups; or

(ii) have a pKa at 25°C in water of less than or equal to 3.5; or

(iii) do not contain any non-carboxyl alkyl hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5.

The one or more carboxylic acids may be selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid. The one or more carboxylic acids may be selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid. The one or more carboxylic acids may be selected from fumaric acid, maleic acid, and malic acid. The one or more carboxylic acids may be selected from fumaric acid and maleic acid. The one or more carboxylic acids may be fumaric acid.

One or both of the primary and secondary aerosol-forming substrates may comprise fumaric acid. In some embodiments, the secondary aerosol-forming substrate comprises fumaric acid and the primary aerosol-forming substrate does not comprise fumaric acid.

One or both of the primary and secondary aerosol-forming substrates may comprise a total tobacco content on a dry weight basis of less than 5 percent by weight, preferably less than 4 percent by weight, more preferably less than 3 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight. One or both of the primary and secondary aerosol-forming substrates may be tobacco-free.

The primary aerosol-forming substrate may comprise a total tobacco content on a dry weight basis of more than 5 percent by weight and the secondary aerosol-forming substrate may comprise a total tobacco content on a dry weight basis of less than 5 percent by weight. In some embodiments, the primary aerosol-forming substrate comprises tobacco and the secondary aerosol-forming substrate is tobacco-free.

One or both of the primary and secondary aerosol-forming substrates may have a total cellulose based agent content on a dry weight basis of between 35 percent by weight and 55 percent by weight, preferably between 40 percent by weight and 50 percent by weight, more preferably between 43 percent by weight and 47 percent by weight. The cellulose based agent may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose.

The cellulose based agent may comprise one or more cellulose based strengthening agents selected from cellulose fibers, microcrystalline cellulose and cellulose powder.

The cellulose based agent may comprise one or more of paper, wood, textile, natural fibers, and artificial fibers.

One or both of the primary and secondary aerosol-forming substrates may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose, and one or more cellulose based strengthening agents selected from cellulose fibers, microcrystalline cellulose and cellulose powder.

One or both of the primary and secondary aerosol-forming substrates may comprise hydroxypropyl methylcellulose, sodium salt of carboxymethyl cellulose, and cellulose fibers.

One or both of the primary and secondary aerosol-forming substrates may comprise on a dry weight basis between 20 percent by weight and 25 percent by weight of hydroxypropyl methylcellulose, between 4 percent by weight and 7 percent by weight of sodium salt of carboxymethyl cellulose, and between 14 percent by weight and 20 percent by weight of cellulose fibers.

One or both of the primary and secondary aerosol-forming substrates may comprise nicotine and fumaric acid, preferably wherein a molar ratio of fumaric acid to nicotine is between 1.3 to 1 and 1.7 to 1, more preferably between 1.4 to 1 and 1.6 to 1, more preferably is about 1.5 to 1.

One or both of the primary and secondary aerosol-forming substrates may be provided in form of a film or gel. The secondary aerosol-forming substrate may be provided in form of a film or gel. In some embodiments, the secondary aerosol-forming substrate is provided in form of a film or gel and the primary aerosol-forming substrate is not provided in form of a film or gel.

One or both of the primary and secondary aerosol-forming substrates may be provided in form of a solid aerosol-forming film. The solid aerosol-forming film may remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius.

The primary aerosol-forming substrate may comprise or consist of a tobacco material. The primary aerosol-forming substrate may comprise or consist of tobacco cut filler. The primary aerosol-forming substrate may comprise or consist of reconstituted tobacco.

The secondary aerosol-forming substrate may be a solid aerosol-forming substrate as described herein, for example a solid aerosol-forming film, and the primary aerosol-forming substrate may comprise or consist of a tobacco material. The substrate wrapper may be a solid aerosol-forming substrate as described herein, for example a solid aerosol-forming film, and the primary aerosol-forming substrate may comprise or consist of a tobacco material. The tobacco material may be cut filler or reconstituted tobacco. The reconstituted tobacco may be tobacco cast leaf. The reconstituted tobacco may be provided in form of a crimped sheet.

Generally, wrapper thicknesses, for example, thicknesses of paper-based wrappers, may be determined in accordance to one of ISO 534:2011 and ASTM E252-06(2021)e1. Generally, for embossed wrappers, the local thickness at a position of an embossment may be less than the thickness at a position without an embossment. As used herein, for embossed wrappers, the thickness of the wrapper refers to the thickness at positions without embossments. For embossed wrappers, the thickness of the wrapper may be determined before the wrapper is being embossed.

Unless defined otherwise, all measurements described herein are performed after conditioning the samples in accordance to ISO Standard 3402:1999.

The substrate wrapper may have a thickness of 60 micrometers or more, preferably 100 micrometers or more, more preferably 120 micrometers or more, more preferably 150 micrometers or more, more preferably 160 micrometers or more, more preferably 170 micrometers or more, more preferably 180 micrometers or more, more preferably 190 micrometers or more, more preferably 200 micrometers or more. The substrate wrapper may have a thickness of between 160 micrometers and 240 micrometers, preferably between 180 micrometers and 220 micrometers.

The substrate wrapper may have a grammage of between 30 to 200 grams per square meter.

The substrate wrapper may have a grammage of between 105 to 200 grams per square meter, preferably between 110 and 17 grams per square meter, more preferably between 120 and 150 grams per square meter, more preferably between 130 and 150 grams per square meter.

The substrate wrapper may have a grammage of between 35 to 100 grams per square meter, preferably between 40 and 90 grams per square meter, more preferably between 50 and 80 grams per square meter, more preferably between 55 and 75 grams per square meter.

The substrate wrapper may have a density of between 0.4 grams per cubic centimeter and 0.9 grams per cubic centimeter, preferably between 0.5 grams per cubic centimeter and 0.8 grams per cubic centimeter, more preferably between 0.6 grams per cubic centimeter and 0.7 grams per cubic centimeter. The thickness and the grammage of the substrate wrapper may be determined using the following method.

Step A: Condition the specimen at 22 ± 2 degrees Celsius and 50 ± 5 percent relative humidity (RH) for 48 hours.

Step B: Use a puncher or cutter to provide three pieces of substrate wrapper.

Use a precision ruler with 1/10mm accuracy to verify whether the individual pieces comply to the sizes predetermined by the puncher or cutter (e.g., 50x50 mm² puncher, 50x300 mm² puncher, or 50 cm² circular cutter). Verify that the three pieces are flat and undamaged.

Step C: Put the three pieces on top of each other and measure their combined thickness using a high precision micrometer for soft materials, with 2 kPa measuring pressure and 0,0001 - 1.25 mm range (e.g., L&W-250-F, L&W-251-B0.2 or equivalent). Divide the value by 3 to obtain the thickness of the substrate wrapper.

Step D: Repeat the measurement two more times on different sample areas. In total, three measurements for each sample must be performed.

Step E: Weigh the three pieces using an analytical balance with 0.1 mg of accuracy (e.g., Mettler Toledo XP205 or equivalent). Repeat the procedure at least once. The grammage is then calculated by dividing a measured weight by the size of the weighed piece.

The density of the substrate wrapper may be calculated by dividing the grammage of the substrate wrapper by its thickness.

The substrate wrapper may have a fracture force per width in a cross direction of between 120 Newton per meter and 160 Newton per meter, preferably between 130 Newton per meter and 150 Newton per meter, more preferably between 135 Newton per meter and 145 Newton per meter.

The substrate wrapper may have a fracture force per width in a machine direction of between 400 Newton per meter and 500 Newton per meter, preferably between 425 Newton per meter and 480 Newton per meter, more preferably between 435 Newton per meter and 470 Newton per meter.

As used herein, the “machine direction” is the direction of forward movement of the forming wrapper on the wrapper-making machine or papermaking machine. The direction perpendicular to this direction is called “cross-direction”.

The fracture force per width of the substrate wrapper may be determined by the following method.

Step A: Condition the specimen at 22 ± 2 degrees Celsius and 50 ± 5 percent relative humidity (RH) for 48 hours. Step B: Use a puncher to punch the specimen into 25 mm or 50 mm wide samples aligned in the direction being tested: machining direction (MD) or cross direction (CD).

Step C: Use a scalpel or similar tool to cut the stripes to a length of 100 to 150 mm if 50 mm wide samples are used, and 150 to 200 mm if 100 mm wide samples are used.

Step D: Use a Universal Tensile/Compression Testing Machine, for example

Instron 5944 or equivalent, for determining the fracture force per width. The fracture force per width is calculated as the force at fracture divided by the width of the sample.

Step E: Repeat steps A to D two more times. In total, three measurements shall be performed.

The substrate wrapper may be in direct physical contact with the primary aerosolforming substrate. In that case, there is no layer of material between the substrate wrapper and the aerosol-forming substrate. The secondary aerosol-forming substrate may be in direct physical contact with the primary aerosol-forming substrate.

The substrate wrapper may extend along the entire length of the aerosol-forming substrate portion. Preferably, the substrate wrapper does not extend beyond longitudinal ends of the aerosol-forming substrate portion.

In addition to the substrate wrapper at least partly circumscribing the aerosol-forming substrate portion, one or more of the components of the aerosol-generating article may be individually circumscribed by their own single component wrapper.

The substrate wrapper may have a single layer structure. The substrate wrapper may consist of the secondary aerosol-forming substrate. The substrate wrapper may be an isotropic material.

The substrate wrapper may have a multi-layer structure. At least one of the layers of the multi-layer structure may comprise the secondary aerosol-forming substrate. The innermost layer facing the aerosol-forming substrate portion may comprise the secondary aerosol-forming substrate. The multi-layer structure may be a dual layer structure. The multilayer structure may comprise a layer of paper, cardboard, plastics, or metal foil. The layer of metal foil may be an aluminium layer.

As used herein, the term “aerosol-forming substrate” relates to materials suitable for use as either one of the primary aerosol-forming substrate and the secondary aerosolforming substrate.

As used herein, the term “aerosol-forming substrate” refers to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may be in solid form or may be in liquid form. The aerosol-forming substrate may be solid or liquid or may comprise both solid and liquid components. An aerosol-forming substrate may be part of an aerosol-generating article. The terms ‘aerosol’ and ‘vapor’ are used synonymously.

The aerosol-forming substrate may comprise one or more of: tobacco, nicotine, an aerosol-forming film, a gel composition, and a flavour agent.

The aerosol-forming substrate may comprise a total aerosol former content on a dry weight basis of at least 10 percent by weight, preferably at least 15 percent by weight, more preferably at least 20 percent by weight, more preferably at least 25 percent by weight, more preferably at least 30 percent by weight, more preferably at least 35 percent by weight, more preferably at least 40 percent by weight, more preferably at least 45 percent by weight, more preferably at least 50 percent by weight.

The aerosol-forming substrate may comprise at least 35 percent by weight of one or more aerosol formers. The aerosol-forming substrate may comprise at least 35 percent by weight of one or more aerosol formers on a dry weight basis of the aerosol-forming substrate. Unless defined otherwise, all percentages by weight described herein are on a dry weight basis.

The aerosol former may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. The aerosol former may be facilitating that the aerosol is substantially resistant to thermal degradation at temperatures typically applied during use of the aerosol-generating article. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1 ,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof. Preferably, the one or more aerosol formers comprise one or both of glycerol and propylene glycol. The one or more aerosol formers may consist of one or both of glycerol and propylene glycol. Preferably, the aerosol-forming substrate comprises glycerol. The terms “glycerine” and “glycerol” are used synonymously herein.

The aerosol-forming substrate may comprise less than or equal to 80 percent by weight of aerosol former on a dry weight basis of the aerosol-forming substrate. The aerosolforming substrate may comprise less than or equal to 60 percent by weight of aerosol former on a dry weight basis of the aerosol-forming substrate. The aerosol-forming substrate may comprise less than or equal to 40 percent by weight of aerosol former on a dry weight basis of the aerosol-forming substrate.

The aerosol-forming substrate may comprise between 35 percent and 80 percent, or between 35 percent and 60 percent, or between 35 percent and 55 percent, or between 35 percent and 50 percent, or between 35 percent and 40 percent by weight of aerosol former on a dry weight basis of the aerosol-forming substrate.

The total aerosol former content of the aerosol-forming substrate may be at least 40 percent by weight, preferably at least 45 percent by weight, more preferably at least 50 percent by weight, more preferably at least 55 percent by weight. The total aerosol former content of the aerosol-forming substrate may be between 35 percent by weight and 75 percent by weight, preferably between 40 percent by weight and 60 percent by weight, more between 45 percent by weight and 55 percent by weight.

The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise one or more carboxylic acids. The aerosol-forming substrate may comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

The one or more carboxylic acids may be selected from fumaric acid, maleic acid, and malic acid. The one or more carboxylic acids may be selected from fumaric acid and maleic acid. The one or more carboxylic acids may be fumaric acid. The one or more carboxylic acids may have a pKa at 25°C in water of less than or equal to 3.5. The aerosolforming substrate may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

The aerosol-forming substrate may comprise between 0.1 percent by weight and 8 percent by weight, preferably between 0.5 percent by weight and 6 percent by weight, more preferably between 0.5 percent by weight and 5 percent by weight, more preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.5 percent by weight and 4 percent by weight, more preferably between 2 percent by weight and 4 percent by weight of one or more carboxylic acids on a dry weight basis.

The aerosol-forming substrate may comprise one or more carboxylic acids that do not contain any non-carboxyl alkyl hydroxyl groups.

The aerosol-forming substrate may comprise nicotine and one or more carboxylic acids, and a molar ratio of total carboxylic acid to nicotine may be between 0.5:1 and 5:1, preferable between 1:1 and 4:1, more preferably between 2:1 and 3.5:1 , more preferably between 0 and 0.3, more preferably between 0 and 0.2, more preferably between 0 and 0.1.

The aerosol-forming substrate may comprise between 0.5 percent by weight and 5 percent by weight, preferably between 0.5 percent by weight and 3 percent by weight, more preferably between 1 percent by weight and 2 percent by weight of fumaric acid on a dry weight basis.

The aerosol-forming substrate may comprise between 0.5 percent by weight and 5 percent by weight, preferably between 0.5 percent by weight and 3 percent by weight, more preferably between 1 percent by weight and 2 percent by weight of maleic acid on a dry weight basis.

The aerosol-forming substrate may comprise one or both of fumaric acid and maleic acid, and the sum of fumaric acid and maleic acid comprised in the aerosol-forming substrate may be between 0.5 percent by weight and 5 percent by weight, preferably between 0.5 percent by weight and 3 percent by weight, more preferably between 1 percent by weight and 2 percent by weight on a dry weight basis.

The aerosol-forming substrate may comprise less than 6 percent by weight, preferably less that 4 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight of malic acid on a dry weight basis.

The aerosol-forming substrate may have a total cellulose based agent content of between 35 percent by weight and 50 percent by weight. The aerosol-forming substrate may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose. The aerosol-forming substrate may comprise one or more cellulose based strengthening agents selected from cellulose fibres, microcrystalline cellulose and cellulose powder.

The aerosol-forming substrate may be an aerosol-forming film. The aerosol-forming substrate may be a solid aerosol-forming film. The solid aerosol-forming film may be solid at room temperature. The solid aerosol-forming film may remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius.

The aerosol-forming substrate may be provided in form of a gel.

The aerosol-forming substrate may comprise a tobacco content on a dry weight basis of less than 75 percent by weight, preferably less than 70 percent by weight, more preferably less than 65 percent by weight, more preferably less than 60 percent by weight, more preferably less than 55 percent by weight, more preferably less than 50 percent by weight, more preferably less than 45 percent by weight, more preferably less than 40 percent by weight, more preferably less than 35 percent by weight, more preferably less than 30 percent by weight, more preferably less than 25 percent by weight, more preferably less than 20 percent by weight, more preferably less than 15 percent by weight, more preferably less than 10 percent by weight, more preferably less than 5 percent by weight, more preferably less than 4 percent by weight, more preferably less than 3 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight.

The aerosol-forming substrate may be substantially tobacco-free. The aerosolforming substrate may be tobacco-free.

The aerosol-forming substrate may comprise one or more carboxylic acids and the aerosol-forming substrate may have a total carboxylic acid content of greater than or equal to 0.5 percent by weight. The aerosol-forming substrate may not comprise iota-carrageenan or kappa-carrageenan.

The aerosol-forming substrate may be a solid aerosol-forming substrate. As used herein with reference to the invention, the term “solid” is used to describe an aerosol-forming substrate that has a stable size and shape and does not flow at room temperature - room temperature is about 23 degrees Celsius.

For example, the aerosol-forming substrate may remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius, between 200 degrees Celsius and 320 degrees Celsius, between 220 degrees Celsius and 300 degrees Celsius, or between 240 degrees Celsius and 280 degrees Celsius.

The aerosol-forming substrate may be an aerosol-forming film.

As used herein, the term “film” is used to describe a solid laminar element having a thickness that is less than the width or length thereof. The film may be self-supporting. In other words, a film may have cohesion and mechanical properties such that the film, even if obtained by casting a film-forming formulation on a support surface, can be separated from the support surface. Alternatively, the film may be disposed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film.

The solid aerosol-forming substrate may be a solid aerosol-forming film.

The aerosol-forming film comprises one or more aerosol formers as described herein, preferably the aerosol-former comprises glycerine, or is glycerine. The aerosol-forming film may have an aerosol former content of at least 35 percent by weight on a dry weight basis. Preferably, the aerosol-forming film has an aerosol former content of at least 40 percent by weight on a dry weight basis. More preferably, the aerosol-forming film has an aerosol former content of at least 45 percent by weight on a dry weight basis. More preferably, the aerosolforming film has an aerosol former content of at least 50 percent by weight on a dry weight basis.

Preferably, the aerosol-forming film has an aerosol former content of no more than 80 percent by weight on a dry weight basis. More preferably, aerosol-forming film has an aerosol former content of no more than 75 percent by weight on a dry weight basis. More preferably, the aerosol-forming film has an aerosol former content of no more than 70 percent by weight on a dry weight basis.

The aerosol-forming substrate may be in the form of an aerosol-forming film comprising a cellulosic based film forming agent, nicotine and an aerosol former. The aerosol-forming film may further comprise a cellulose based strengthening agent. The aerosol-forming film may further comprise water, preferably 30 percent by weight of less of water. As used herein with reference to the invention, the term “thickness” is used to describe the minimum dimension between opposite, substantially parallel surfaces of a solid aerosol-forming film.

The solid aerosol-forming film may have a thickness of greater than or equal to 0.05 millimeters, greater than or equal to 0.1 millimeters, greater than or equal to 0.2 millimeters, or greater than or equal to 0.3 millimeters. The solid aerosol-forming film may have a thickness of less than or equal to 1.2 millimeters, less than or equal to 1 millimeter, less than or equal to 0.8 millimeters, less than or equal to 0.6 millimeters, or less than or equal to 0.4 millimeters.

The solid aerosol-forming film may have a basis weight of greater than or equal to 85 grams per square meter, greater than or equal to 100 grams per square meter, greater than or equal to 120 grams per square meter, or greater than or equal to 140 grams per square meter. The solid aerosol-forming film may have a basis weight of less than or equal to 300 grams per square meter, less than or equal to 280 grams per square meter, or less than or equal to 260 grams per square meter.

The solid aerosol-forming film may be formed by any suitable method. For example, the solid aerosol-forming film may be formed by batch casting, continuous casting or extrusion.

The solid aerosol-forming film may be self-supporting. In other words, the properties of the solid aerosol-forming film may be such that, even if the solid aerosol-forming film is formed by casting a slurry onto a support surface, the solid aerosol-forming film can be separated from the support surface.

The solid aerosol-forming film may be disposed on a support or the solid aerosolforming film may be sandwiched between other materials. This may enhance the mechanical stability of the solid aerosol-forming film. For example, the solid aerosol-forming film may be disposed on a laminar support.

The solid aerosol-forming film may be cut or otherwise divided into a plurality of strips or shreds that may be wrapped to form the aerosol-forming portion wrapped by the wrapper.

The solid aerosol-forming film may be gathered before insertion into the aerosolforming portion. The solid aerosol-forming film may be textured. This may facilitate gathering of the solid aerosol-forming film before insertion into the aerosol-forming portion.

As used herein with reference to the invention, the term “textured” is used to describe a solid aerosol-forming film that has been crimped, embossed, debossed, perforated or otherwise deformed. Textured solid aerosol-forming film may comprise a plurality of spacedapart indentations, protrusions, perforations or a combination thereof.

The solid aerosol-forming film may be crimped. As used herein with reference to the invention, the term “crimped” is intended to be synonymous with the term “creped” and is used to describe a solid aerosol-forming film having a plurality of substantially parallel ridges or corrugations.

The solid aerosol-forming film may be incorporated directly into the aerosol-forming portion.

The solid aerosol-forming film may be applied to a laminar support before being incorporated into the aerosol-forming portion. For example, the solid aerosol-forming film may be applied to the surface of a sheet material. Suitable sheet materials for use as the laminar support include, but are not limited, to: paper; cardboard; and homogenised plant material. For example, the solid aerosol-forming film may be applied to a paper sheet, an aluminium coated paper sheet, or a polyethylene coated paper sheet.

The laminar support with the solid aerosol-forming film applied thereto may be cut or otherwise divided into a plurality of strips or shreds as described above.

The laminar support with the solid aerosol-forming film applied thereto may be gathered as described above.

The laminar support with the solid aerosol-forming film applied thereto may be textured as described above.

As used herein with reference to the invention, the term “aerosol former” is used to describe a compound that, in use, facilitates formation of the aerosol, and that preferably is substantially resistant to thermal degradation at the operating temperature of an aerosolgenerating article or aerosol-generating system comprising the solid aerosol-forming substrate.

Examples of suitable aerosol formers include: polyhydric alcohols, such as 1,3- butanediol, glycerine, 1 ,3-propanediol, propylene glycol, and triethylene glycol; 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 aerosol-forming substrate may have a total aerosol former content of greater than or equal to 35 percent by weight. The aerosol-forming substrate may have a total aerosol former content of greater than or equal to 40 percent by weight, or greater than or equal to 45 percent by weight, or greater than or equal to 50 percent by weight.

As used herein with reference to the invention, the term “total aerosol former content” is used to describe the combined content of all aerosol formers in the aerosol-forming substrate.

The solid aerosol-forming substrate may have a total aerosol former content of greater than or equal to 46 percent by weight, greater than or equal to 48 percent by weight, greater than or equal to 50 percent by weight, or greater than or equal to 52 percent by weight.

The solid aerosol-forming substrate may have a total aerosol former content of less than or equal to 62 percent by weight, less than or equal to 60 percent by weight, less than or equal to 58 percent by weight, less than or equal to 56 percent by weight, or less than or equal to 54 percent by weight.

The solid aerosol-forming substrate may have a total aerosol former content of between 42 percent by weight and 62 percent by weight, between 46 percent by weight and 60 percent by weight, between 46 percent by weight and 58 percent by weight, between 46 percent by weight and 56 percent by weight, or between 46 percent by weight and 54 percent by weight.

Preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols.

The solid aerosol-forming substrate may have a total polyhydric alcohol content of greater than or equal to 45 percent by weight, greater than or equal to 46 percent by weight, greater than or equal to 48 percent by weight, greater than or equal to 50 percent by weight, or greater than or equal to 52 percent by weight.

Preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols selected from 1 ,3-butanediol, glycerine, 1 ,3-propanediol, propylene glycol, and triethylene glycol.

More preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols selected from glycerine and propylene glycol. Most preferably, the solid aerosol-forming substrate comprises glycerine.

The solid aerosol-forming substrate may comprise one or more carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5.

As used herein with reference to the invention, the term “carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5” is used to describe monoprotic carboxylic acids having a pKa at 25°C in water of less than or equal to 3.5 and polyprotic carboxylic acids having a pKa1 at 25°C in water of less than or equal to 3.5.

As used herein with reference to the invention, the term “total carboxylic acid content” is used to describe the combined content of all carboxylic acids in the solid aerosolgenerating substrate. For example, where the solid aerosol-generating substrate comprises a plurality of carboxylic acids consisting of benzoic acid and fumaric acid, the term “total carboxylic acid content” describes the combined benzoic acid content and fumaric acid content of the solid aerosol-generating substrate. The solid aerosol-generating substrate may have a total carboxylic acid content of greater than or equal to 1 percent by weight, greater than or equal to 1.5 percent by weight, or greater than or equal to 2 percent by weight.

The solid aerosol-generating substrate may have a total carboxylic acid content of less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight.

The solid aerosol-generating substrate may have a total carboxylic acid content of between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a total carboxylic acid content of between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between 1 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a total carboxylic acid content of between 1.5 percent by weight and 8 percent by weight, between 1.5 percent by weight and 6 percent by weight, or between 1.5 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a total carboxylic acid content of between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between 2 percent by weight and 4 percent by weight.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be greater than or equal to 0.5:1, greater than or equal to 1:1 , greater than or equal to 1.5:1, or greater than or equal to 2: 1.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be less than or equal to 5:1, less than or equal to 4.5:1, less than or equal to 4:1, or less than or equal to 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be between 0.5:1 and 5:1, between 0.5:1 and 4.5:1, between 0.5:1 and 4:1 , or between 0.5:1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be between 1:1 and 5:1, between 1:1 and 4.5:1, between 1:1 and 4:1, or between 1:1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be between 1.5:1 and 5:1, between 1.5:1 and 4.5:1, between 1.5:1 and 4:1 , or between 1.5:1 and 3.5:1.

The molar ratio of total carboxylic acid to nicotine in the solid aerosol-generating substrate may be between 2:1 and 5:1, between 2:1 and 4.5:1, between 2:1 and 4:1, or between 2:1 and 3.5:1. The solid aerosol-generating substrate may have a fumaric acid content of greater than or equal to 0.5 percent by weight, greater than or equal to 1 percent by weight, greater than or equal to 1.5 percent by weight, or greater than or equal to 2 percent by weight.

The solid aerosol-generating substrate may have a fumaric acid content of less than or equal to 8 percent by weight, less than or equal to 6 percent by weight, or less than or equal to 4 percent by weight.

The solid aerosol-generating substrate may have a fumaric acid content of between 0.5 percent by weight and 8 percent by weight, between 0.5 percent by weight and 6 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a fumaric acid content of between 1 percent by weight and 8 percent by weight, between 1 percent by weight and 6 percent by weight, or between 1 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a fumaric acid content of between 1.5 percent by weight and 8 percent by weight, between 1.5 percent by weight and 6 percent by weight, or between 1.5 percent by weight and 4 percent by weight.

The solid aerosol-generating substrate may have a fumaric acid content of between 2 percent by weight and 8 percent by weight, between 2 percent by weight and 6 percent by weight, or between 2 percent by weight and 4 percent by weight.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be greater than or equal to 0.5:1, greater than or equal to 1:1, greater than or equal to 1.5:1, or greater than or equal to 2: 1.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be less than or equal to 4:1, or less than or equal to 3.5:1 , less than or equal to 3:1 , or less than or equal to 2.5:1.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be between 0.5:1 and 4:1 , between 0.5:1 and 3.5:1, between 0.5:1 and 3:1, or between 0.5:1 and 2.5:1.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be between 1:1 and 4:1, between 1:1 and 3.5:1, between 1:1 and 3:1 , or between 1:1 and 2.5:1.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be between 1.5:1 and 4:1 , between 1.5:1 and 3.5:1, between 1.5:1 and 3:1, or between 1.5:1 and 2.5:1.

The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be between 2:1 and 4:1, between 2:1 and 3.5:1, between 2:1 and 3:1 , or between 2:1 and 2.5:1. The solid aerosol-forming substrate may comprise one or more cellulose based agents.

As used herein with reference to the invention, the term “cellulose based agent” is used to describe a cellulosic substance. The term “cellulose based film-forming agent” may be used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

Examples of cellulose based agents include cellulose based film-forming agents, cellulose based strengthening agents and cellulose based binding agents.

As used herein with reference to the invention, the term “total cellulose based agent” is used to describe the combined content of all cellulose based agents in the solid aerosolforming substrate. For example, where the solid aerosol-forming substrate comprises a plurality of cellulose based agents consisting of a cellulose based film-forming agent, a cellulose based strengthening agent, and a cellulose based binding agent, the term “total cellulose based agent content” describes the combined cellulose based film-forming agent content, cellulose based strengthening agent content, and cellulose based binding agent content of the solid aerosol-forming substrate.

The solid aerosol-forming substrate may have a total cellulose based agent content of greater than or equal to 25 percent by weight, or greater than or equal to 30 percent by weight. Preferably, the solid aerosol-forming substrate has a total cellulose based agent content of greater than or equal to 35 percent by weight. The solid aerosol-forming substrate may have a total cellulose based agent content of greater than or equal to 36 percent by weight, greater than or equal to 38 percent by weight, or greater than or equal to 40 percent by weight.

The solid aerosol-forming substrate may have a total cellulose based agent content of less than or equal to 52 percent by weight, less than or equal to 50 percent by weight, less than or equal to 48 percent by weight, less than or equal to 46 percent by weight, or less than or equal to 44 percent by weight.

The solid aerosol-forming substrate may have a total cellulose based agent content of between 35 percent by weight and 52 percent by weight, between 35 percent by weight and 50 percent by weight, between 35 percent by weight and 48 percent by weight, between 35 percent by weight and 46 percent by weight, or between 35 percent by weight and 44 percent by weight.

The solid aerosol-forming substrate may comprise one or more cellulose based filmforming agents. As used herein with reference to the invention, the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

Advantageously, the solid aerosol-forming substrate may comprise one or more cellulose based film-forming agents selected from carboxymethyl cellulose (CMC), ethylcellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methylcellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC). Preferably, the solid aerosol-forming substrate comprises carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof.

More preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), and combinations thereof.

In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

The one or more cellulose based film-forming agents may act as a binding agent for the solid aerosol-forming substrate.

The solid aerosol-forming substrate may have a total cellulose based film-forming agent content of greater than or equal to 15 percent by weight, greater than or equal to 20 percent by weight, or greater than or equal to 25 percent by weight.

The solid aerosol-forming substrate may have a total cellulose based film-forming agent content of less than or equal to 40 percent by weight, less than or equal to 35 percent by weight, or less than or equal to 30 percent by weight.

The solid aerosol-forming substrate may have a total cellulose based film-forming agent content of between 10 percent by weight and 40 percent by weight, between 15 percent by weight and 35 percent by weight, or between 15 percent by weight and 30 percent by weight. The aerosol-forming film may have a cellulose based film-forming agent content of between 10 percent and 40 percent by weight, or between 15 percent and 35 percent by weight, or between 20 percent and 30 percent by weight, on a dry weight basis.

The solid aerosol-forming substrate may comprise one or more cellulose based strengthening agents.

Inclusion of one or more cellulose based strengthening agents in the solid aerosolforming substrate may advantageously increase the tensile strength of the solid aerosol- forming substrate. In particular, where the solid aerosol-forming substrate is a solid aerosolforming film, inclusion of one or more cellulose based strengthening agents in the solid aerosol-forming substrate may advantageously increase the tensile strength of the solid aerosol-forming film. A solid aerosol-forming substrate having a higher tensile strength may advantageously be less likely to deteriorate or break during manufacture and storage.

Advantageously, the solid aerosol-forming substrate may comprise one or more cellulose based strengthening agents selected from cellulose fibres, cellulose powder, and microcrystalline cellulose (MCC). Preferably, the cellulose based strengthening agent is selected from the group consisting of cellulose fibres, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

Preferably, the solid aerosol-forming substrate comprises cellulose fibres. Cellulose fibres may be particularly effective at increasing the tensile strength of the solid aerosolforming substrate.

The aerosol-forming film may have a cellulose based strengthening agent content of between 0.5 percent and 40 percent by weight on a dry weight basis, or between 5 percent and 30 percent by weight on a dry weight basis, or between 10 percent and 25 percent by weight on a dry weight basis.

The solid aerosol-forming substrate may have a total cellulose based strengthening agent content of greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, or greater than or equal to 15 percent by weight.

As used herein with reference to the invention, the term “total cellulose based strengthening agent content” is used to describe the combined content of all cellulose based strengthening agents in the solid aerosol-forming substrate.

The solid aerosol-forming substrate may have a total cellulose based strengthening agent content of less than or equal to 30 percent by weight, less than or equal to 25 percent by weight, or less than or equal to 20 percent by weight.

The solid aerosol-forming substrate may have a total cellulose based strengthening agent content of between 5 percent by weight and 30 percent by weight, between 5 percent by weight and 25 percent by weight, or between 5 percent by weight and 20 percent by weight.

The aerosol-forming film may further comprise a carboxymethyl cellulose, preferably sodium carboxymethyl cellulose.

The aerosol-forming film may have a carboxymethyl cellulose content of between 1 percent and 15 percent by weight, or between 2 percent and 12 percent by weight, or between 4 percent and 10 percent by weight on a dry weight basis.

The solid aerosol-forming substrate may comprise water. The solid aerosol-forming substrate may have a water content of greater than or equal to 5 percent by weight, greater than or equal to 10 percent by weight, greater than or equal to 15 percent by weight, or greater than or equal to 17 percent by weight based on the total weight of the solid aerosol-forming substrate.

The solid aerosol-forming substrate may have a water content of less than or equal to 35 percent by weight, less than or equal to 30 percent by weight, or less than or equal to 25 percent by weight based on the total weight of the solid aerosol-forming substrate.

The solid aerosol-forming substrate may have a water content of between 5 percent by weight and 35 percent by weight, between 5 percent by weight and 30 percent by weight, or between 5 percent by weight and 25 percent by weight based on the total weight of the solid aerosol-forming substrate.

The solid aerosol-forming substrate may comprise one or more non-cellulose based thickening agents.

As used herein with reference to the invention, the term “non-cellulose based thickening agent” is used to describe a non-cellulosic substance that, when added to an aqueous or non-aqueous liquid composition, increases the viscosity of the liquid composition without substantially modifying its other properties. The one or more non-cellulose based thickening agents may increase stability, and improve suspension of components in the liquid composition. A thickening agent may also be referred to as a “thickener” or a “rheology modifier” or “viscosifying agent”.

The solid aerosol-forming substrate may comprise one or more non-cellulose based thickening agents selected from alginates, gellan gum, guar gum, gum arabic, locust bean gum, pectins, starches, and xanthan gum.

The solid aerosol-forming substrate may have a total non-cellulose based thickening agent content of greater than or equal to 1 percent by weight, greater than or equal to 2 percent by weight, or greater than or equal to 3 percent by weight.

The solid aerosol-forming substrate may have a total non-cellulose based thickening agent content of less than or equal to 10 percent by weight, less than or equal to 8 percent by weight, or less than or equal to 6 percent by weight.

The solid aerosol-forming substrate may have a total non-cellulose based thickening agent content of between 1 percent by weight and 10 percent by weight, between 1 percent by weight and 8 percent by weight, or between 1 percent by weight and 6 percent by weight.

The solid aerosol-forming substrate may comprise one or more flavourants.

Suitable flavourants are known in the art and include, but are not limited to, menthol.

As used herein with reference to the invention, the term “menthol” is used to describe the compound 2-isopropyl-5-methylcyclohexanol in any of its isomeric forms. The solid aerosol-forming substrate may have a total flavourant content of greater than or equal to 0.5 percent by weight, greater than or equal to 1 percent by weight, greater than or equal to 2 percent by weight, or greater than or equal to 3 percent by weight.

The solid aerosol-forming substrate may have a total flavourant content of less than or equal to 6 percent by weight, less than or equal to 5 percent by weight, or less than or equal to 4 percent by weight.

The solid aerosol-forming substrate may have a total flavourant content of between 0.5 percent by weight and 6 percent by weight, between 0.5 percent by weight and 5 percent by weight, or between 0.5 percent by weight and 4 percent by weight.

The solid aerosol-forming substrate may have a total flavourant content of between 1 percent by weight and 6 percent by weight, between 1 percent by weight and 5 percent by weight, or between 1 percent by weight and 4 percent by weight.

The solid aerosol-forming substrate may be a substantially tobacco-free solid aerosolforming substrate.

As used herein with reference to the invention, the term “substantially tobacco-free solid aerosol-forming substrate” is used to describe a solid aerosol-forming substrate having a tobacco content of less than 1 percent by weight. For example, the solid aerosol-forming substrate may have a tobacco content of less than 0.75 percent by weight, less than 0.5 percent by weight, or less than 0.25 percent by weight.

The solid aerosol-forming substrate may be a tobacco-free aerosol-forming film.

As used herein with reference to the invention, the term “tobacco-free solid aerosolforming substrate” is used to describe a solid aerosol-forming substrate having a tobacco content of 0 percent by weight.

The aerosol-forming film preferably comprises nicotine.

As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In embodiments in which the aerosol-forming film comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

The aerosol-forming film may comprise natural nicotine or synthetic nicotine.

The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix.

The aerosol-forming film may comprise one or more monoprotic nicotine salts.

As used herein with reference to the invention, the term “monoprotic nicotine salt” is used to describe a nicotine salt of a monoprotic acid.

Preferably, the aerosol-forming film comprises at least 0.5 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises at least 1 percent by weight of nicotine on a dry weight basis. Even more preferably, the aerosol- forming film comprises at least 2 percent by weight of nicotine on a dry weight basis. In addition, or as an alternative, the aerosol-forming film preferably comprises less than 10 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises less than 8 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises less than 6 percent by weight of nicotine on a dry weight basis.

For example, the aerosol-forming film may comprise between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

The aerosol-forming film may be a substantially tobacco-free aerosol-forming film.

In preferred embodiments, the aerosol-forming film comprises an acid. More preferably, the aerosol-forming film comprises one or more organic acids. Even more preferably, the aerosol-forming film comprises one or more carboxylic acids. In particularly preferred embodiments, the acid is lactic acid, benzoic acid, fumaric acid or levulinic acid.

Preferably, the aerosol-forming film comprises between 0.25 percent and 3.5 percent by weight of an acid, or between 0.5 percent and 3 percent by weight of an acid, or between 1 percent and 2.5 percent by weight of an acid, on a dry weight basis.

The aerosol-forming film may have a thickness from about 0.1 millimeter to about 1 millimeter, more preferably from about 0.1 millimeter to about 0.75 millimeter, even more preferably from about 0.1 millimeter to about 0.5 millimeter. In particularly preferred embodiments, a layer of the film-forming composition is formed that has a thickness from about 50 micrometers to 400 micrometers, more preferably from about 100 micrometers to 200 micrometers.

The aerosol-forming film may optionally be provided on a suitable carrier element.

The aerosol-forming substrate may comprise a gel composition The aerosol-forming substrate may comprise a gel composition that includes nicotine, at least one gelling agent and the aerosol former. The gel composition is preferably substantially tobacco free.

The preferred weight ranges for nicotine in the gel composition are the same as those defined above in relation to aerosol-forming films.

The gel composition preferably comprises at least 50 percent by weight of aerosol former, more preferably at least 60 percent by weight, more preferably at least 70 percent by weight of aerosol former, on a dry weight basis. The gel composition may comprise up to 80 percent by weight of aerosol former. The aerosol former in the gel composition is preferably glycerol.

The gel composition preferably includes at least one gelling agent. Preferably, the gel composition includes a total amount of gelling agents in a range from about 0.4 percent by weight to about 10 percent by weight, or from about 0.5 percent by weight to about 8 percent by weight, or from about 1 percent by weight to about 6 percent by weight, or from about 2 percent by weight to about 4 percent by weight, or from about 2 percent by weight to about 3 percent by weight.

The term “gelling agent” refers to a compound that homogeneously, when added to a 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of about 0.3 percent by weight, forms a solid medium or support matrix leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond crosslinking gelling agents, and ionic crosslinking gelling agents.

The term “hydrogen-bond crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via hydrogen bonding.

The hydrogen-bond crosslinking gelling agent may include one or more of a galactomannan, gelatin, agarose, or konjac gum, or agar. The hydrogen-bond crosslinking gelling agent may preferably include agar.

The term “ionic crosslinking gelling agent” refers to a gelling agent that forms non- covalent crosslinking bonds or physical crosslinking bonds via ionic bonding.

The ionic crosslinking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. The ionic crosslinking gelling agent may preferably include low acyl gellan.

The gelling agent may include one or more biopolymers. The biopolymers may be formed of polysaccharides.

Biopolymers include, for example, gellan gums (native, low acyl gellan gum, high acyl gellan gums with low acyl gellan gum being preferred), xanthan gum, alginates (alginic acid), agar, guar gum, and the like. The composition may preferably include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include the two biopolymers in substantially equal weights. The composition may include the three biopolymers in substantially equal weights.

The gel composition may further include a viscosifying agent. The viscosifying agent combined with the hydrogen-bond crosslinking gelling agent and the ionic crosslinking gelling agent appears to surprisingly support the solid medium and maintain the gel composition even when the gel composition comprises a high level of glycerol.

The term “viscosifying agent” refers to a compound that, when added homogeneously into a 25°C, 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight, increases the viscosity without leading to the formation of a gel, the mixture staying or remaining fluid. The gel composition preferably includes the viscosifying agent in a range from about 0.2 percent by weight to about 5 percent by weight, or from about 0.5 percent by weight to about 3 percent by weight, or from about 0.5 percent by weight to about 2 percent by weight, or from about 1 percent by weight to about 2 percent by weight.

The viscosifying agent may include one or more of xanthan gum, carboxymethylcellulose, microcrystalline cellulose, methyl cellulose, gum Arabic, guar gum, lambda carrageenan, or starch. The viscosifying agent may preferably include xanthan gum.

The gel composition may further include a divalent cation. Preferably the divalent cation includes calcium ions, such as calcium lactate in solution. Divalent cations (such as calcium ions) may assist in the gel formation of compositions that include gelling agents such as the ionic crosslinking gelling agent, for example. The ion effect may assist in the gel formation. The divalent cation may be present in the gel composition in a range from about 0.1 to about 1 percent by weight, or about 0.5 percent by weight.

The gel composition may further include an acid. The acid may comprise a carboxylic acid. The carboxylic acid may include a ketone group. Preferably the carboxylic acid may include a ketone group having less than about 10 carbon atoms, or less than about 6 carbon atoms or less than about 4 carbon atoms, such as levulinic acid or lactic acid. Preferably this carboxylic acid has three carbon atoms (such as lactic acid).

The gel composition preferably comprises some water. The gel composition is more stable when the composition comprises some water.

Preferably the gel composition comprises between about 8 percent by weight to about 32 percent by weight water, or from about 15 percent by weight to about 25 percent by weight water, or from about 18 percent by weight to about 22 percent by weight water, or about 20 percent by weight water.

Preferably, where a gel composition is used, the aerosol-forming substrate comprises a porous medium loaded with the gel composition. Advantages of a porous medium loaded with the gel composition is that the gel composition is retained within the porous medium, and this may aid manufacturing, storage or transport of the gel composition. It may assist in keeping the desired shape of the gel composition, especially during manufacture, transport, or use.

The term “porous” is used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material.

The porous medium may be any suitable porous material able to hold or retain the gel composition. Ideally the porous medium can allow the gel composition to move within it. In specific embodiments the porous medium comprises natural materials, synthetic, or semisynthetic, or a combination thereof. In specific embodiments the porous medium comprises sheet material, foam, or fibres, for example loose fibres; or a combination thereof. In specific embodiments the porous medium comprises a woven, non-woven, or extruded material, or combinations thereof. Preferably the porous medium comprises, cotton, paper, viscose, PLA, or cellulose acetate, of combinations thereof. Preferably the porous medium comprises a sheet material, for example, cotton or cellulose acetate. In a particularly preferred embodiment, the porous medium comprises a sheet made from cotton fibres.

The porous medium may be crimped or shredded. The porous medium may be in the form of a sheet, thread or tubular element.

The aerosol-forming substrate may have added a portion of plant material, for example tobacco material, as long as the aerosol former content does not fall below 5 percent by weight, preferably does not fall below 35 percent by weight.

The aerosol-forming substrate may comprise tobacco particles. With reference to the present invention, the term “tobacco particles” describes particles of any plant member of the genus Nicotiana. The term “tobacco particles” encompasses ground or powdered tobacco leaf lamina, ground or powdered tobacco leaf stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco. In a preferred embodiment, the tobacco particles are substantially all derived from tobacco leaf lamina. By contrast, isolated nicotine and nicotine salts are compounds derived from tobacco but are not considered tobacco particles for purposes of the invention and are not included in the percentage of particulate plant material.

The aerosol-forming substrate may comprise plant material and an aerosol former. The plant material may be a plant material comprising an alkaloid, more preferably a plant material comprising nicotine, and more preferably a tobacco-containing material.

Alkaloids are a class of naturally occurring nitrogen-containing organic compounds. Alkaloids are found mostly in plants, but are also found in bacteria, fungi and animals. Examples of alkaloids include, but are not limited to, caffeine, nicotine, theobromine, atropine and tubocurarine. A preferred alkaloid is nicotine, which may be found in tobacco.

As used herein, the term “tobacco material” is used to describe any material comprising tobacco, including, but not limited to, tobacco leaf, tobacco rib, tobacco stem, tobacco stalk, tobacco dust, expanded tobacco, reconstituted tobacco material and homogenised tobacco material.

As used herein, the term "flavourant" refers to a composition having organoleptic properties, which provide a sensory experience to the user, for example to enhance the flavour of aerosol. A flavourant can be used to deliver a gustatory sensation (taste), an olfactory sensation (smell), or both a gustatory and an olfactory sensation to the user, for example when inhaling the aerosol. The aerosol-forming substrate may comprise, on a dry weight basis, an aerosol former content of at least 35 percent by weight, a tobacco content of less than 35 percent by weight, and between 0.5 percent by weight and 4 percent by weight of one or more carboxylic acids. The aerosol-forming substrate may comprise, on a dry weight basis, an aerosol former content of at least 35 percent by weight, a tobacco content of less than 35 percent by weight, between 0.5 percent by weight and 4 percent by weight of one or more carboxylic acids, and less than 4 percent by weight of nicotine.

The aerosol-forming substrate may be a solid aerosol-forming film having the composition as shown in Table I below.

The solid aerosol- generating film may be prepared by:

(1) mixing the components shown in Table I together with water using agitation to form a slurry;

(2) casting a layer of the slurry onto a plane surface to form a film having a thickness of between 600 and 1000 micrometers;

(3) leaving the film on the plane surface to solidify; and

(3) drying the film by heating the film to 140 degrees Celsius for 8 minutes to form a solid aerosol-forming film.

The aerosol-forming substrate may be a solid aerosol-forming film having the composition as shown in Table I below, but where the fumaric acid is partially or completely substituted by one or more other carboxylic acids. For example, the fumaric acid may be partially or completely substituted by one or more carboxylic acids selected from malic acid, maleic acid, lactic acid, and benzoic acid.

The aerosol-forming substrate may be provided in form of a film or gel.

The aerosol-forming substrate may be provided in form of a film having a thickness of from about 0.1 millimeter to about 1 millimeter, preferably from about 0.05 millimeter to about 0.75 millimeter, more preferably from about 0.05 millimeter to about 0.5 millimeter, more preferably from 50 micrometers to 400 micrometers, more preferably from 100 micrometers to 200 micrometers.

The total mass of aerosol-forming substrate in the aerosol-generating article may be between 200 milligrams and 400 milligrams, preferably between 240 milligrams and 340 milligrams, more preferably between 250 milligrams and 290 milligrams, more preferably between 260 milligrams and 280 milligrams.

The aerosol-forming substrate portion may define a substantially cylindrical shape. The cylindrical shape of the aerosol-forming substrate portion may have a diameter in a range from about 3 millimeters to about 10 millimeters, preferably from about 6 millimeters to about 8 millimeters, more preferably from about 6.5 millimeters to about 7.5 millimeters.

The aerosol-generating article may comprise one or more susceptor elements. The one or more susceptor elements may be comprised within the aerosol-forming substrate portion. For example, one or more elongate susceptor elements may be arranged substantially longitudinally within the aerosol-forming substrate portion and in thermal contact with the aerosol-forming substrate.

As used herein, the terms “susceptor” and “susceptor element” refer to an element that heats up when subjected to an alternating magnetic field. This may be the result of eddy currents induced in the susceptor element, hysteresis losses, or both eddy currents and hysteresis losses. During use, the susceptor element is located in thermal contact or close thermal proximity with an aerosol-forming substrate received in the aerosol-generating device or cartridge. In this manner, the aerosol-forming substrate is heated by the susceptor such that an aerosol is formed.

The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. Preferred susceptor elements comprise a metal or carbon.

A preferred susceptor element may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor element may be, or comprise, aluminium.

The aerosol-forming substrate portion may comprise the susceptor element. The susceptor element may be at least partly circumscribed by one or both of the primary and secondary aerosol-forming substrates. The susceptor element may be completely surrounded by one or both of the primary and secondary aerosol-forming substrates.

The susceptor element may be in the form of a pin, rod, strip or blade.

The aerosol-generating article may comprise a downstream section located downstream of the aerosol-forming substrate portion. The downstream section is preferably located immediately downstream of the aerosol-forming substrate portion. The downstream section of the aerosol-generating article preferably extends between the aerosol-forming substrate portion and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements.

The downstream section of an aerosol-generating article according to the present invention preferably comprises a hollow tubular cooling element provided downstream of the aerosol-forming substrate portion. The hollow tubular cooling element may advantageously provide an aerosol-cooling element for the aerosol-generating article.

The hollow tubular cooling element may be provided immediately downstream of the aerosol-forming substrate portion. In other words, the hollow tubular cooling element may abut a downstream end of the aerosol-forming substrate portion. The hollow tubular cooling element may define an upstream end of the downstream section of the aerosol-generating article. The downstream end of the aerosol-generating article may coincide with the downstream end of the downstream section. In some embodiments, the downstream section of the aerosol-generating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element. In other embodiments, the downstream section comprises two or more hollow tubular elements, as described below.

As used throughout the present disclosure, the term "hollow tubular element" denotes a generally elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term "tubular" will be used in the following with reference to a tubular element having a substantially cylindrical cross-section and defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it will be understood that alternative geometries (for example, alternative cross-sectional shapes) of the tubular element may be possible. The hollow tubular cooling element may be an individual, discrete element of the aerosol-generating article which has a defined length and thickness.

The aerosol-generating article may comprise a ventilation zone at a location along the downstream section. In some embodiments, the aerosol-generating article may comprise a ventilation zone at a location along the hollow tubular cooling element. Such, or any, ventilation zone may extend through the peripheral wall of the hollow tubular cooling element. As such, fluid communication is established between the flow channel internally defined by the hollow tubular cooling element and the outer environment. The hollow tubular cooling element may comprise a paper-based material. The hollow tubular cooling element may comprise at least one layer of paper. The paper may be very rigid paper. The paper may be crimped paper, such as crimped heat resistant paper or crimped parchment paper. The hollow tubular cooling element may be a cardboard tube.

The ventilation zone may typically comprise a plurality of perforations through the peripheral wall of the hollow tubular cooling element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during manufacturing of the aerosol-generating article. Preferably, each circumferential row of perforations comprises from 8 to 30 perforations.

As discussed in the present disclosure, the downstream section may comprise a downstream filter segment. The downstream filter segment may extend to a downstream end of the downstream section. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article. The downstream filter segment may also be referred to as mouth-end filter.

The downstream filter segment may be located downstream of a hollow tubular cooling element, which is described above. The downstream filter segment may extend between the hollow tubular cooling element and the downstream end of the aerosolgenerating article.

The downstream filter segment is preferably a solid plug, which may also be described as a ‘plain’ plug and is non-tubular. The filter segment therefore preferably has a substantially uniform transverse cross section.

The downstream filter segment is preferably formed of a fibrous filtration material. The fibrous filtration material may be for filtering the aerosol that is generated from the aerosol-forming substrate. Suitable fibrous filtration materials would be known to the skilled person. Particularly preferably, the at least one downstream filter segment comprises a cellulose acetate filter segment formed of cellulose acetate tow.

In certain preferred embodiments, the downstream section includes a single downstream filter segment. In alternative embodiments, the downstream section includes two or more downstream filter segments axially aligned in an abutting end to end relationship with each other. The downstream filter segment may optionally comprise a flavourant, which may be provided in any suitable form. For example, the downstream filter segment may comprise one or more capsules, beads or granules of a flavourant, or one or more flavour loaded threads or filaments.

Unless otherwise specified, the resistance to draw (RTD) of a component or the aerosol-generating article is measured in accordance with ISO 6565-2015. The RTD refers the pressure required to force air through the full length of a component. The terms “pressure drop” or “draw resistance” of a component or article may also refer to the “resistance to draw”. Such terms generally refer to the measurements in accordance with ISO 6565-2015 normally carried out at a volumetric flow rate of 17.5 milliliters per second at the output or downstream end of the measured component at a temperature of 22 degrees Celsius, a pressure of 101 kPa (about 760 Torr) and a relative humidity of 60%. Conditions for smoking and smoking machine specifications are set out in ISO Standard 3308 (ISO 3308:2000). Atmosphere for conditioning and testing are set out in ISO Standard 3402 (ISO 3402:1999).

The resistance to draw (RTD) may be expressed with the units of pressure “millimeter(s) of water gauge” (mmWG).

The aerosol-generating article may comprise one or more hollow tubular elements. The one or more hollow tubular elements may form part of a downstream section of the aerosol-generating article arranged downstream of the aerosol-forming substrate portion. The one or more hollow tubular elements may comprise one or both of a hollow acetate tube (HAT) and a fine hollow acetate tube (FHAT). Such hollow tubes are cylindrical components which may be made from cellulose acetate and which are provided with centrally arranged axial holes. The dimensions of the hollow tubes such as their outer diameter or the diameter of the hole vary and can be designed according to the demands of the respective products.

The aerosol-generating article may comprise a mouth-end filter. The mouth-end filter may be arranged downstream of the aerosol-forming substrate portion. The mouth-end filter may be arranged at a proximal end of the aerosol-generating article. The mouth-end filter may be arranged downstream of and directly abutting the FHAT. The mouth-end filter may comprise a filter material. The filter material may be a filamentary material, for example cellulose acetate.

Aerosol-generating articles according to the present disclosure comprise an upstream section located upstream of the aerosol-forming substrate portion. The upstream section is preferably located immediately upstream of the aerosol-forming substrate portion. The upstream section preferably extends between the upstream end of the aerosol-generating article and the aerosol-forming substrate portion. The upstream section comprises one or more upstream elements located upstream of the aerosol-forming substrate portion. The aerosol-generating articles of the present invention preferably comprise an upstream element located upstream of and adjacent to the aerosol-forming substrate portion. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-forming substrate portion Furthermore, the presence of an upstream element helps to prevent any loss of the substrate, which may be advantageous, for example, if the substrate contains particulate plant material.

An upstream element of the upstream section may be made of any material suitable for use in an aerosol-generating article. The upstream element may, for example, be made of a same material as used for one of the other components of the aerosol-generating article, such as the downstream filter segment or the hollow tubular cooling element. Suitable materials for forming the upstream element include filter materials, ceramic, polymer material, cellulose acetate, cardboard, zeolite or aerosol-forming substrate. The upstream element may comprise a plug of cellulose acetate. The upstream element may comprise a hollow acetate tube, or a cardboard tube.

The upstream section may comprise a front plug. The front plug may be arranged upstream of and directly abutting the aerosol-forming substrate portion. The front plug may be arranged at a distal end of the aerosol-generating article. The front plug may comprise a filter material.

The aerosol-generating article in accordance with the invention may have an overall length of at least 40 millimeters, or at least 50 millimeters, or at least 60 millimeters.

An overall length of an aerosol-generating article in accordance with the invention may be less than or equal to 90 millimeters, or less than or equal to 85 millimeters, or less than or equal to 80 millimeters.

In some embodiments, an overall length of the aerosol-generating article is preferably from 50 millimeters to 90 millimeters, more preferably from 60 millimeters to 90 millimeters, even more preferably from 70 millimeters to 90 millimeters. In other embodiments, an overall length of the aerosol-generating article is preferably from 50 millimeters to 85 millimeters, more preferably from 60 millimeters to 85 millimeters, even more preferably from 70 millimeters to 85 millimeters. In further embodiments, an overall length of the aerosolgenerating article is preferably from 50 millimeters to 80 millimeters, more preferably from 60 millimeters to 80 millimeters, even more preferably from 70 millimeters to 80 millimeters. In an exemplary embodiment, an overall length of the aerosol-generating article is 75 millimeters.

In some embodiments, an overall length of the aerosol-generating article is preferably from 40 millimeters to 70 millimeters, more preferably from 45 millimeters to 70 millimeters. In other embodiments, an overall length of the aerosol-generating article is preferably from 40 millimeters to 60 millimeters, more preferably from about 45 millimeters to about 60 millimeters. In further embodiments, an overall length of the aerosol-generating article is preferably from 40 millimeters to 50 millimeters, more preferably from 45 millimeters to 50 millimeters. In an exemplary embodiment, an overall length of the aerosol-generating article is about 45 millimeters.

Preferably, the aerosol-generating article has an external diameter of at least about 5 millimeters. More preferably, the aerosol-generating article has an external diameter of at least 5.25 millimeters. Even more preferably, the aerosol-generating article has an external diameter of at least 5.5 millimeters.

The aerosol-generating article preferably has an external diameter of less than or equal to 8 millimeters. More preferably, the aerosol-generating article has an external diameter of less than or equal to 7.5 millimeters. Even more preferably, the aerosolgenerating article has an external diameter of less than or equal to 7 millimeters.

The aerosol-generating article may have an external diameter of between 5 millimeters and 8 millimeters, or between 5 millimeters and 7.5 millimeters, or between 5 millimeters and 7 millimeters, or between 5.25 millimeters and 8 millimeters, or between 5.25 millimeters and 7.5 millimeters, or between 5.25 millimeters and 7 millimeters, or between 5.5 millimeters and 8 millimeters, or between 5.5 millimeters and 7.5 millimeters, or between 5.5 millimeters and 7 millimeters.

The external diameter of the aerosol-generating article may be substantially constant over the whole length of the article. As an alternative, different portions of the aerosolgenerating article may have different external diameters.

Preferably, the overall RTD of the aerosol-generating article is at least 10 millimeters of water gauge. For example, the overall RTD of the aerosol-generating article may be at least 20 millimeters of water gauge, at least 30 millimeters of water gauge, at least 35 millimeters of water gauge, or at least 40 millimeters of water gauge.

The overall RTD of the aerosol-generating article may be no more than 70 millimeters of water gauge. For example, the overall RTD of the aerosol-generating article may be no more than 65 millimeters of water gauge, no more than 60 millimeters of water gauge, or no more than 55 millimeters of water gauge, or no more than 50 millimeters.

The overall RTD of the aerosol-generating article may be between 10 millimeters of water gauge and 70 millimeters of water gauge. For example, the overall RTD of the aerosolgenerating article may be between 20 millimeters of water gauge and 65 millimeters of water gauge, between 30 millimeters of water gauge and 60 millimeters of water gauge, between 35 millimeters of water gauge and 55 millimeters of water gauge, or between 40 millimeters of water gauge and 50 millimeters of water gauge. The aerosol-generating article may comprise ventilation holes. The ventilation holes may promote nucleation of the aerosol. The ventilation holes may assist in cooling the airflow. The ventilation holes may be provided in the FHAT. The FHAT may comprise 11 ventilation holes each having a diameter of 0.11 millimeter.

The total resistance to draw of the aerosol-generating article may be between 5 millimeters of water gauge and 200 millimeters of water gauge, preferably between 10 millimeters of water gauge and 150 millimeters of water gauge, more preferably between 20 millimeters of water gauge and 100 millimeters of water gauge, more preferably between 80 millimeters of water gauge and 80 millimeters of water gauge, more preferably between 40 millimeters of water gauge and 60 millimeters of water gauge, more preferably between 45 millimeters of water gauge and 55 millimeters of water gauge, more preferably about 48 millimeters of water gauge.

The aerosol-generating article may have a cylindrical shape. The aerosol-forming substrate portion may have a cylindrical shape.

The aerosol-generating article may comprise, in order from a proximal end to a distal end of the article, a mouth-end filter, one or more intermediate elements, an aerosol-forming substrate portion, and, optionally, a front plug. The one or more intermediate elements may comprise one or more of a HAT, a FHAT, and a PI_A plug. The total length of the article may be about 45 millimeters and the length of the length of the aerosol-forming substrate portion may be about 11 millimeters. The wrapper may circumscribe the complete article or only a portion thereof.

According to an embodiment of the invention there is provided an aerosol-generating system. The aerosol-generating system comprises the aerosol-generating article as described herein. The aerosol-generating system comprises an aerosol-generating device. The aerosol-generating device may comprise a cavity configured for at least partly inserting the aerosol-generating article into the cavity. The cavity may be a heating chamber. The aerosol-generating device may comprise an internal heating element arranged for being inserted into the aerosol-generating article, when the aerosol-generating article is at least partly inserted into the heating chamber. The aerosol-generating device may comprise an inductor coil. The inductor coil may at least partly circumscribe the heating chamber. The inductor coil may be arranged to coaxially circumscribe the heating chamber. The inductor coil may be arranged to inductively heat a susceptor element. The susceptor element may be part of an internal heating element of the aerosol-generating device. The susceptor element may be part of the aerosol-generating article. The inductor coil may be arranged to inductively heat a susceptor of the aerosol-generating article when the aerosol-generating article is at least partly inserted into the heating chamber. As used herein, the term “aerosol-generating article” refers to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. An aerosol-generating article may be disposable. An aerosol-generating article comprising an aerosol-forming substrate comprising tobacco may be referred to herein as a tobacco stick.

As used herein, the term “aerosol-generating device” refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. An aerosol-generating device may interact with one or both of an aerosol-generating article comprising an aerosol-forming substrate, and a cartridge comprising an aerosol-forming substrate. In some examples, the aerosol-generating device may heat the aerosol-forming substrate to facilitate release of volatile compounds from the substrate. An electrically operated aerosol-generating device may comprise an atomiser, such as an electric heater, to heat the aerosol-forming substrate to form an aerosol.

As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device with an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of the aerosol-generating device with the aerosol-generating article. In the aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device cooperate to generate an aerosol.

As used herein, the term "tubular element" is used to denote an elongate element defining a lumen or airflow passage along a longitudinal axis thereof. In particular, the term "tubular" is used herein to encompass any tubular element having a substantially cylindrical cross-section and defining at least one airflow passage establishing an uninterrupted fluid communication between an upstream end of the tubular element and a downstream end of the tubular element. However, it will be understood that alternative geometries of the tubular element may be possible.

As used herein, the terms “upstream” and “front”, and “downstream” and “rear”, are used to describe the relative positions of components, or portions of components, of the aerosol generating article in relation to the direction in which airflows through the aerosol generating article during use thereof. Aerosol generating articles according to the invention comprise a proximal end through which, in use, an aerosol exits the article. The proximal end of the aerosol generating article may also be referred to as the mouth end or the downstream end. The mouth end is downstream of the distal end. The distal end of the aerosol generating article may also be referred to as the upstream end. Components, or portions of components, of the aerosol generating article may be described as being upstream or downstream of one another based on their relative positions between the proximal end of the aerosol generating article and the distal end of the aerosol generating article. The front of a component, or portion of a component, of the aerosol generating article is the portion at the end closest to the upstream end of the aerosol generating article. The rear of a component, or portion of a component, of the aerosol generating article is the portion at the end closest to the downstream end of the aerosol generating article.

As used herein, the term “longitudinal” refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article.

The term “length” denotes the dimension of a component of the aerosol-generating article in the longitudinal direction. For example, it may be used to denote the dimension of the rod or of the elongate tubular elements in the longitudinal direction.

As used herein with reference to the present invention, the term “transverse” is used to describe the direction perpendicular to the longitudinal direction. Unless otherwise stated, references to the “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refer to the transverse cross-section.

As used herein, the term “proximal” refers to a user-end, or mouth-end of the aerosolgenerating article, and the term “distal” refers to the end opposite to the proximal end.

Components of aerosol-generating articles according to the present invention may be described as being upstream or downstream of one another based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosolgenerating article.

The aerosol-generating device suitable for use with an aerosol-generating article as described herein may comprise a cavity for receiving at least part of the aerosol-generating article and a heater for heating the aerosol-forming substrate portion of the aerosolgenerating article when the aerosol-generating article is received within the cavity. The cavity may be a heating chamber.

The aerosol-generating device may comprise a heater for heating the aerosolgenerating article. The heater may be any suitable type of heater. Preferably, in the present invention, the heater is an external heater. Preferably, the heater externally heats the aerosol-forming substrate portion when the aerosol-generating article is received within the aerosol-generating device. Such an external heater may circumscribe the aerosol-generating article when inserted in or received within the aerosol-generating device.

In some embodiments, the heater is arranged for insertion into an aerosol-forming substrate when the aerosol-forming substrate is received within the cavity.

The heater may be positioned within the device cavity, or heating chamber. The heater may comprise at least one heating element. The at least one heating element may be any suitable type of heating element. In some embodiments, the device comprises only one heating element. In some embodiments, the device comprises a plurality of heating elements.

The heater may comprise a resistive heating arrangement.

In some embodiments, the heater comprises an inductive heating arrangement. The inductive heating arrangement may comprise an inductor coil and a power supply configured to provide high frequency oscillating current to the inductor coil.

The heater may comprise an inductive heating element. The inductive heating element may be a susceptor element. A susceptor element may be arranged such that, when the aerosol-generating article is received in the cavity of the aerosol-generating device, the oscillating electromagnetic field generated by the inductor coil induces a current in the susceptor element, causing the susceptor element to heat up.

The susceptor element may be part of the aerosol-generating device. The susceptor element may be part of the aerosol-generating article.

During use, the heater may be controlled to operate within a defined operating temperature range, below a maximum operating temperature. An operating temperature range between about 150 degrees Celsius and about 300 degrees Celsius in the heating chamber (or device cavity) is preferable. The operating temperature range of the heater may be between about 150 degrees Celsius and about 250 degrees Celsius.

The aerosol-generating device may comprise a power supply. The power supply may be a DC power supply. In some embodiments, the power supply is a battery. The power supply may be a nickel-metal hydride battery, a nickel cadmium battery, or a lithium based battery, for example a lithium-cobalt, a lithium-iron-phosphate or a lithium-polymer battery. However, in some embodiments the power supply may be another form of charge storage device, such as a capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for one or more user operations, for example one or more aerosol-generating experiences.

Below, there 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.

Example E1 : An aerosol-generating article, comprising an aerosol-forming substrate portion comprising a primary aerosol-forming substrate; and a substrate wrapper surrounding at least a part of the aerosol-forming substrate portion and comprising a secondary aerosol-forming substrate; wherein one or both of the primary and secondary aerosol-forming substrates comprise one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids; preferably wherein one or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

Example E2: The aerosol-generating article according to Example E1, wherein the secondary aerosol-forming substrate comprises one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

Example E3: The aerosol-generating article according to Example E1 or Example E2, wherein the primary aerosol-forming substrate comprises a tobacco material.

Example E4: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise a total nicotine content on a dry weight basis of between 0.1 percent by weight and 6 percent by weight, more preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.0 percent by weight and 2.0 percent by weight, more preferably between 1.2 percent by weight and 1.8 percent by weight.

Example E5: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise a total aerosol former content on a dry weight basis of at least 30 percent by weight, more preferably at least 35 percent by weight, more preferably at least 40 percent by weight, more preferably at least 45 percent by weight, more preferably at least 50 percent by weight.

Example E6: The aerosol-generating article according to any of the preceding examples, wherein the aerosol former comprises glycerin.

Example E7: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise a total carboxylic acid content on a dry weight basis of between 0.1 percent by weight and 6 percent by weight, preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.0 percent by weight and 2.5 percent by weight, more preferably between 1.4 percent by weight and 2.0 percent by weight.

Example E8: The aerosol-generating article according to any of the preceding examples, wherein the one or more carboxylic acids:

(ii) have a pKa at 25°C in water of less than or equal to 3.5; or (iii) do not contain any non-carboxyl alkyl hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5.

Example E9: The aerosol-generating article according to any of the preceding examples, wherein the one or more carboxylic acids are selected from lactic acid, levulinic acid, acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid, preferably wherein the one or more carboxylic acids are selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid, more preferably wherein the one or more carboxylic acids are selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

Example E10: The aerosol-generating article according to any of the preceding examples, wherein the one or more carboxylic acids are selected from fumaric acid, maleic acid, and malic acid, preferably wherein the one or more carboxylic acids are selected from fumaric acid and maleic acid, more preferably wherein the one or more carboxylic acids is fumaric acid.

Example E11: The aerosol-generating article according to Example E9, wherein the one or more carboxylic acids are selected from fumaric acid, maleic acid, and malic acid, preferably wherein the one or more carboxylic acids are selected from fumaric acid and maleic acid, more preferably wherein the one or more carboxylic acids is fumaric acid.

Example E12: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise fumaric acid.

Example E13: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise a total tobacco content on a dry weight basis of less than 5 percent by weight, preferably less than 4 percent by weight, more preferably less than 3 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight, more preferably wherein one or both of the primary and secondary aerosol-forming substrates are tobacco-free.

Example E14: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates have a total cellulose based agent content on a dry weight basis of between 35 percent by weight and 55 percent by weight, preferably between 40 percent by weight and 50 percent by weight, more preferably between 43 percent by weight and 47 percent by weight. Example E15: The aerosol-generating article according to any of the preceding examples, wherein the cellulose based agent comprises one or more cellulose based filmforming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose.

Example E16: The aerosol-generating article according to any of the preceding examples, wherein the cellulose based agent comprises one or more cellulose based strengthening agents selected from cellulose fibers, microcrystalline cellulose and cellulose powder.

Example E17: The aerosol-generating article according to any of the preceding examples, wherein the cellulose based agent comprises one or more of paper, wood, textile, natural fibers, and artificial fibers.

Example E18: The aerosol-generating article according to any of the preceding examples, wherein the secondary aerosol-forming substrate comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose, preferably wherein the secondary aerosol-forming substrate comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose and one or more cellulose based strengthening agents selected from cellulose fibers, microcrystalline cellulose and cellulose powder.

Example E19: The aerosol-generating article according to Example E18, wherein the secondary aerosol-forming substrate comprises hydroxypropyl methylcellulose, sodium salt of carboxymethyl cellulose, and cellulose fibers.

Example E20: The aerosol-generating article according to Example E19, wherein the secondary aerosol-forming substrate comprises on a dry weight basis between 20 percent by weight and 25 percent by weight of hydroxypropyl methylcellulose, between 4 percent by weight and 7 percent by weight of sodium salt of carboxymethyl cellulose, and between 14 percent by weight and 20 percent by weight of cellulose fibers.

Example E21: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates comprise nicotine and fumaric acid, preferably wherein a molar ratio of fumaric acid to nicotine is between 1.2 to 1 and 1.8 to 1, more preferably between 1.3 to 1 and 1.7 to 1, more preferably is between 1.4 to 1 and 1.6 to 1; more preferably is about 1.5 to 1.

Example E22: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates are provided in form of a film or gel.

Example E23: The aerosol-generating article according to any of the preceding examples, wherein one or both of the primary and secondary aerosol-forming substrates are provided in form of a solid aerosol-forming film, preferably wherein the solid aerosol-forming film remains solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius.

Example E24: The aerosol-generating article according to any of the preceding examples, wherein the primary and secondary aerosol-forming substrates have the same composition, or wherein the primary and secondary aerosol-forming substrates have different compositions.

Example E25: The aerosol-generating article according to any of the preceding examples, wherein the substrate wrapper has a thickness of 60 micrometers or more, preferably 100 micrometers or more, more preferably 120 micrometers or more, more preferably 150 micrometers or more, more preferably 160 micrometers or more, more preferably 170 micrometers or more, more preferably 180 micrometers or more, more preferably 190 micrometers or more, more preferably 200 micrometers or more, or wherein the substrate wrapper has a thickness of between 160 micrometers and 240 micrometers, preferably between 180 micrometers and 220 micrometers.

Example E26: The aerosol-generating article according to any of the preceding examples, wherein the substrate wrapper extends along the entire length of the aerosolforming substrate portion, preferably wherein the substrate wrapper does not extend beyond longitudinal ends of the aerosol-forming substrate portion.

Example E27: The aerosol-generating article according to any of the preceding examples, wherein the substrate wrapper has a single layer structure.

Example E28: The aerosol-generating article according to any of the preceding examples, wherein the substrate wrapper consists of the secondary aerosol-forming substrate.

Example E29: The aerosol-generating article according to Example E27 or Example E28, wherein the substrate wrapper is an isotropic material.

Example E30: The aerosol-generating article according to any of Examples E1 to E26, wherein the substrate wrapper has a multi-layer structure, and wherein one of the layers of the multi-layer structure comprises the secondary aerosol-forming substrate, preferably, wherein the innermost layer facing the aerosol-forming substrate portion comprises the secondary aerosol-forming substrate.

Example E31: The aerosol-generating article according to Example E30, wherein the multi-layer structure is a dual layer structure.

Example E32: The aerosol-generating article according to Example E30 or Example E31, wherein the multi-layer structure comprises a layer of paper, cardboard, plastics, or metal foil, preferably wherein the multi-layer structure comprises an aluminium layer. Example E33: An aerosol-generating article for use in an aerosol-generating system, the aerosol-generating article comprising: an aerosol-forming substrate portion comprising a primary aerosol-forming substrate; and a substrate wrapper surrounding at least a part of the aerosol-forming substrate portion and comprising a secondary aerosol-forming substrate; wherein one or both of the primary and secondary aerosol-forming substrates are provided as a solid aerosol-forming substrate, wherein the solid aerosol-forming substrate comprises nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids that: (i) do not contain any non-carboxyl alkyl hydroxyl groups and do not contain any ketone groups; or (ii) have a pKa at 25°C in water of less than or equal to 3.5; or (iii) do not contain any non- carboxyl alkyl hydroxyl groups, do not contain any ketone groups, and have a pKa at 25°C in water of less than or equal to 3.5, and wherein the solid aerosol-forming substrate has a total cellulose based agent content of at least 35 percent by weight, a total aerosol former content of greater than or equal to 45 percent by weight, and a total carboxylic acid content of at least 0.5 percent by weight.

Example E34: The aerosol-generating article according to Example E33, comprising a susceptor in direct contact with the solid aerosol-forming substrate.

Example E35: The aerosol-generating article according to Example E33 or Example E34, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

Example E36: The aerosol-generating article according to any of Examples E33 to E35, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid.

Example E37: The aerosol-generating article according to any of Examples E33 to E35, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

Example E38: The aerosol-generating article according to any of Examples E33 to E37, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from acetic acid, benzoic acid, citric acid, fumaric acid, and maleic acid. Example E39: The aerosol-generating article according to any one of any of Examples E33, E34, E35, or E37, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid.

Example E40: The aerosol-generating article according to any of Examples E33 to E39, wherein the solid aerosol-forming substrate comprises one or more carboxylic acids selected from fumaric acid and maleic acid.

Example E41: The aerosol-generating article according to any of Examples E33 to E40, wherein the solid aerosol-forming substrate comprises fumaric acid.

Example E42: The aerosol-generating article according to Example E41 , wherein the molar ratio of fumaric acid to nicotine in the solid aerosol-forming substrate is between 0.5:1 and 4:1, preferably between 1.2:1 and 1.8:1 , more preferably between 1.3:1 and 1.7:1, more preferably between 1.4:1 and 1.6:1; more preferably is about 1.5:1.

Example E43: The aerosol-generating article according to any of Examples E33 to E42, wherein the solid aerosol-forming substrate does not comprise iota-carrageenan or kappa-carrageenan.

Example E44: The aerosol-generating article according to any of Examples E33 to E43, wherein the solid aerosol-forming substrate further comprises one or more carboxylic acids selected from lactic acid and levulinic acid.

Example E45: The aerosol-generating article according to any of Examples E33 to E44, wherein the solid aerosol-forming substrate has a total carboxylic acid content of between 1 percent and 6 percent by weight.

Example E46: The aerosol-generating article according to any of Examples E33 to E45, wherein the molar ratio of total carboxylic acid to nicotine in the solid aerosol-forming substrate is between 0.5:1 and 5:1.

Example E47: The aerosol-generating article according to any of Examples E33 to E46, wherein the solid aerosol-forming substrate has a total cellulose based agent content of between 35 percent by weight and 50 percent by weight.

Example E48: The aerosol-generating article according to any of Examples E33 to E47, wherein the solid aerosol-forming substrate comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose.

Example E49: The aerosol-generating article according to any of Examples E33 to E48, wherein the solid aerosol-forming substrate comprises one or more cellulose based strengthening agents selected from cellulose fibres, microcrystalline cellulose and cellulose powder. Example E50: The aerosol-generating article according to any of Examples E33 to E49, wherein the aerosol-generating article comprises a susceptor in direct contact with the solid aerosol-forming substrate, and wherein the solid aerosol-forming substrate at least partially surrounds the susceptor.

Example E51: The aerosol-generating article according to any of Examples E33 to E50, wherein the solid aerosol-forming substrate is a solid aerosol-forming film.

Example E52: The aerosol-generating article according to any of Examples E33 to E51 , wherein the solid aerosol-forming film remains solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius.

Example E53: An aerosol-generating system comprising the aerosol-generating article according to any of the preceding examples and an aerosol-generating device comprising a cavity configured for at least partly inserting the aerosol-generating article into the cavity.

Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

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

Figs. 1a to 1c show aerosol-generating articles;

Figs. 2a and 2b show aerosol-generating articles;

Figs. 3a and 3b show aerosol-generating articles; and

Figs. 4a and 4b show aerosol-generating articles.

Figs. 1a to 1c show aerosol-generating articles in cross-sectional views.

The article of Fig. 1a comprises a mouth-end filter 10 located at a proximal end of the article. The article further comprises a PLA (poly lactic acid) plug 12, a hollow acetate tube 14, and an aerosol-forming substrate portion 16 comprising a primary aerosol-forming substrate as described herein. The article is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

An outer diameter of the article may be about 7 millimeters. A total length of the article may be about 45 millimeters. In one embodiment, a length of the mouth-end filter 10 is about 15 millimeters, a length of the PLA plug 12 is about 10 millimeters, a length of the hollow acetate tube 14 is about 8 millimeters, and a length of the aerosol-forming substrate portion 16 is about 12 millimeters. In one embodiment, a length of the mouth-end filter 10 is about 12 millimeters, a length of the PLA plug 12 is about 13 millimeters, a length of the hollow acetate tube 14 is about 8 millimeters, and a length of the aerosol-forming substrate portion 16 is about 12 millimeters.

The article of Fig. 1b is mainly identical to the article of Fig. 1a with the exception that the article of Fig. 1b comprises a sheet-like susceptor element 20 arranged centrally within the aerosol-forming substrate portion 16. The susceptor element 20 is configured to be inductively heatable by an inductor coil of an aerosol-generating device.

The article of Fig. 1c is mainly identical to the article of Fig. 1a with the exceptions that, in the article of Fig. 1c, the substrate wrapper 18 does not extend beyond longitudinal ends of the aerosol-forming substrate portion 16, and that the article of Fig. 1c further comprises an outer wrapper 28. The outer wrapper 28 may be a paper wrapper, for example a conventional tipping wrapper. Optionally, the article of Fig. 1c may further comprise a sheet-like susceptor element 20 (not shown).

Figs. 2a and 2b show aerosol-generating articles in cross-sectional views.

The article of Fig. 2a comprises a mouth-end filter 10, a fine hollow acetate tube 22, a hollow acetate tube 14, an aerosol-forming substrate portion 16, and a front plug 24. The front plug 24 may be a filter plug. The aerosol-forming substrate portion 16 comprises a primary aerosol-forming substrate as described herein. The article is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

An outer diameter of the article may be about 7 millimeters. A total length of the article may be about 45 millimeters. In one embodiment, a length of the mouth-end filter 10 is about 12 millimeters, a length of the fine hollow acetate tube 22 is about 8 millimeters, a length of the hollow acetate tube 14 is about 8 millimeters, a length of the aerosol-forming substrate portion 16 is about 12 millimeters, and a length of the front plug 24 is about 5 millimeters. In one embodiment, a length of the mouth-end filter 10 is about 12 millimeters, a length of the fine hollow acetate tube 22 is about 8 millimeters, a length of the hollow acetate tube 14 is about 7 millimeters, a length of the aerosol-forming substrate portion 16 is about 12 millimeters, and a length of the front plug 24 is about 6 millimeters.

The article of Fig. 2a may comprise a susceptor element (not shown) arranged within the aerosol-forming substrate portion 16.

The article of Fig. 2b is mainly identical to the article of Fig. 2a with the exceptions that, in the article of Fig. 2b, the substrate wrapper 18 does not extend beyond longitudinal ends of the aerosol-forming substrate portion 16, and that the article of Fig. 2a further comprises an outer wrapper 28. The outer wrapper 28 may be a paper wrapper, for example a conventional tipping wrapper.

Figs. 3a and 3b show aerosol-generating articles in cross-sectional views.

The article of Fig. 3a comprises a mouth-end filter 10, a fine hollow acetate tube 22, a hollow acetate tube 14, an aerosol-forming substrate portion 16 comprising a primary aerosol-forming substrate as described herein, and a front plug 24.

The aerosol-forming substrate portion 16 may comprise an optional susceptor 20. The front plug 24 may be a filter plug. A distal portion of the article is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

A proximal portion of the article is circumscribed by a mouthpiece wrapper 44. A circumferential row of ventilation holes 46 is provided in an area where the mouthpiece wrapper 44 overlaps the substrate wrapper 18. The ventilation holes 46 may be provided in one or both of the fine hollow acetate tube 22, the mouthpiece wrapper 44, and the substrate wrapper 18.

An outer diameter of the article may be about 7 millimeters, preferably 7.1 millimeters. A total length of the article may be about 45 millimeters. In one embodiment, a length of the mouth-end filter 10 is about 12 millimeters, a length of the fine hollow acetate tube 22 is about 9 millimeters, a length of the hollow acetate tube 14 is about 8 millimeters, a length of the aerosol-forming substrate portion 16 is about 11 millimeters, and a length of the front plug 24 is about 5 millimeters.

The article of Fig. 3b comprises a hollow mouthpiece tube 48, for example a hollow cylindrical tube made of cellulose acetate, at a proximal end of the article. The hollow mouthpiece tube 48 defines an internal cavity that extends all the way from an upstream end of the hollow mouthpiece tube 48 to a downstream end of a mouth-end filter 10. The internal cavity is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity. The hollow mouthpiece tube 48 does not substantially contribute to the overall RTD of the aerosol-generating article.

The article of Fig. 3b may have an overall length of about 75 millimeters and an external diameter of about 6.7 millimeters. The length of the hollow mouthpiece tube 48 may be about 6 millimeters and the external diameter may be about 6.7 millimeters. The wall thickness of the hollow mouthpiece tube 48 may be about 1 millimeter. The article further comprises a mouth-end filter 10. The mouth-end filter 10 may have a length of about 10 millimeters. An external diameter of the mouth-end filter 10 may be about 6.7 millimeters.

The article further comprises a hollow tube 50, for example a cardboard tube. The hollow tube 50 does not substantially contribute to the overall RTD of the aerosol-generating article. In more detail, the RTD of the hollow tube 50 is about 0 millimeters of water gauge. The hollow tube 50 may have a length of about 25 millimeters or more, an external diameter of about 6.7 millimeters, and an internal diameter of about 6.2 millimeters. Thus, a thickness of a peripheral wall of the hollow tube 50 may be about 0.25 millimeter.

The hollow tube 50 may comprise one or more rows of ventilation holes 46 arranged circumferentially around the hollow tube 50 in a cross-section that is substantially perpendicular to a longitudinal axis of the article. A ventilation level of the aerosol-generating article may be about 75 percent.

At a distal end, the article comprises an aerosol-forming substrate portion 16 comprising a primary aerosol-forming substrate as described herein. The aerosol-forming substrate portion 16 is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

Additionally, an outer wrapper 44 circumscribing at least a portion of the aerosolgenerating article may be provided. The outer wrapper 44 may be a paper wrapper, for example a conventional tipping wrapper. The outer wrapper 44 may also comprise ventilation holes 46. If present, the outer wrapper 44 may overlie the portion of the substrate wrapper 18 that overlies the hollow tube 50. This way, the outer wrapper 44 effectively joins the mouthend filter 10 to the rest of the components of the article. The width of the outer wrapper 44 may be about 26 millimeters.

In one embodiment, the aerosol-generating article of Fig. 3b has an overall length of about 80 millimeters and an external diameter of about 6.5 millimeters, the hollow tube 50 has a length of about 25 millimeters or more, the mouth-end filter 10 has a length of about 10 millimeters, and the length of the hollow mouthpiece tube 48 is about 6 millimeters.

Figs. 4a and 4b show aerosol-generating articles in cross-sectional views.

The article of Fig. 4a comprises an aerosol-forming substrate portion 16 comprising a primary aerosol-forming substrate as described herein. The aerosol-forming substrate portion 16 is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

A downstream section comprises a hollow tube 50 and a mouth-end filter 10. The hollow tube 50 may comprise one or more rows of ventilation holes 46. An upstream section comprises a front plug 24. The front plug 24 may be provided in the form of a filled cylindrical plug of cellulose acetate tow, or may be provided in the form of a hollow cylindrical plug of cellulose acetate tow having a wall thickness of about 1 millimeter. Additionally, one or more outer wrappers 44 circumscribing at least a portion of the aerosol-generating article may be provided.

The aerosol-generating article may have an overall length of about 45 millimeters and an external diameter of about 7.2 millimeters. The overall length of the downstream section may be about 20 millimeters to 30 millimeters. The length of the mouth-end filter 10 may be about 7 millimeters. The overall length of the upstream section may be about 5 millimeters.

Fig. 4b shows an aerosol-generating article comprising an aerosol-forming substrate portion 16 at a distal end thereof. The aerosol-forming substrate portion 16 comprises a primary aerosol-forming substrate as described herein. The aerosol-forming substrate portion 16 is circumscribed by a substrate wrapper 18 comprising a secondary aerosol-forming substrate as described herein. One or both of the primary and secondary aerosol-forming substrates comprise nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

A downstream section comprises a hollow tube 50 and a mouth-end filter 10. The hollow tube 50 may comprise one or more rows of ventilation holes 46.

The aerosol-generating article of Fig. 4b may have an overall length of about 45 millimeters and an external diameter of about 7.2 millimeters. The hollow tube 50 may have a length of about 20 to 30 millimeters, an external diameter of about 7.2 millimeters, and an internal diameter of about 6.7 millimeters. Thus, a thickness of a peripheral wall of the hollow tube 50 is about 0.25 millimeters. The mouth-end filter 10 may have a length of about 5 millimeters to 7 millimeters and an external diameter of about 7.2 millimeters. The mouth-end filter 10 may comprise a low-density, cellulose acetate filter segment. The RTD of the mouthend filter 10 may be about 8 millimeters of water gauge. The mouth-end filter 10 may be individually wrapped by a plug wrap (not shown). Additionally, one or more outer wrappers 44 circumscribing at least a portion of the aerosol-generating article may be provided.

Claims

1. An aerosol-generating article, comprising an aerosol-forming substrate portion comprising a primary aerosol-forming substrate; and a substrate wrapper surrounding at least a part of the aerosol-forming substrate portion and comprising a secondary aerosol-forming substrate; wherein the secondary aerosol-forming substrate comprises nicotine, one or more cellulose based agents, one or more aerosol formers, and one or more carboxylic acids.

2. The aerosol-generating article according to claim 1 , wherein the first aerosolforming substrate comprises a tobacco material.

3. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate comprises a total aerosol former content on a dry weight basis of at least 30 percent by weight, more preferably at least 35 percent by weight, more preferably at least 40 percent by weight, more preferably at least 45 percent by weight, more preferably at least 50 percent by weight.

4. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate comprises a total carboxylic acid content on a dry weight basis of between 0.1 percent by weight and 6 percent by weight, preferably between 0.5 percent by weight and 4 percent by weight, more preferably between 1.0 percent by weight and 2.5 percent by weight, more preferably between 1.4 percent by weight and 2.0 percent by weight.

5. The aerosol-generating article according to any of the preceding claims, wherein the one or more carboxylic acids are selected from lactic acid, levulinic acid, acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid, preferably wherein the one or more carboxylic acids are selected from acetic acid, adipic acid, benzoic acid, citric acid, fumaric acid, maleic acid, malic acid, myristic acid, oxalic acid, salicylic acid, stearic acid, succinic acid, and undecanoic acid, more preferably wherein the one or more carboxylic acids are selected from acetic acid, benzoic acid, citric acid, fumaric acid, maleic acid, and malic acid.

6. The aerosol-generating article according to any of the preceding claims, wherein the one or more carboxylic acids are selected from fumaric acid, maleic acid, and malic acid, preferably wherein the one or more carboxylic acids are selected from fumaric acid and maleic acid, more preferably wherein the one or more carboxylic acids is fumaric acid.

7. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate comprises a total tobacco content on a dry weight basis of less than 5 percent by weight, preferably less than 4 percent by weight, more preferably less than 3 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight, more preferably wherein the secondary aerosol-forming substrate is tobacco-free.

8. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate has a total cellulose based agent content on a dry weight basis of between 35 percent by weight and 55 percent by weight, preferably between 40 percent by weight and 50 percent by weight, more preferably between 43 percent by weight and 47 percent by weight.

9. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate comprises one or more cellulose based film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methylcellulose.

10. The aerosol-generating article according to claim 9, wherein the secondary aerosol-forming substrate comprises one or more cellulose based strengthening agents selected from cellulose fibers, microcrystalline cellulose and cellulose powder.

11. The aerosol-generating article according to any of the preceding claims, wherein the secondary aerosol-forming substrate comprises nicotine and fumaric acid, preferably wherein a molar ratio of fumaric acid to nicotine is between 1.2 to 1 and 1.8 to 1, more preferably between 1.3 to 1 and 1.7 to 1, more preferably between 1.4 to 1 and 1.6 to 1, more preferably is about 1.5 to 1.

12. The aerosol-generating article according to any of the preceding claims, wherein the primary and secondary aerosol-forming substrates have the same composition.

13. The aerosol-generating article according to any of the preceding claims, wherein the substrate wrapper consists of the secondary aerosol-forming substrate.

14. An aerosol-generating system comprising the aerosol-generating article according to any of the preceding claims and an aerosol-generating device comprising a cavity configured for at least partly inserting the aerosol-generating article into the cavity.