WO2022171601A1

WO2022171601A1 - Cartridge for aerosol-generating system

Info

Publication number: WO2022171601A1
Application number: PCT/EP2022/052963
Authority: WO
Inventors: Thomas JOHAENTGES; Marc Schäfer; Madoka HASEGAWA
Original assignee: Jt International Sa
Priority date: 2021-02-09
Filing date: 2022-02-08
Publication date: 2022-08-18
Also published as: JP2024505799A; EP4291053A1; CN116940252A

Abstract

A cartridge for use with an aerosol-generating system comprises a first compartment comprising a solid aerosol-forming material and a second compartment comprising liquid aerosol-forming material stored in a liquid retention element comprising loosely- packed solid particles configured to retain a liquid aerosol-forming material in the interstices of particles and their surfaces; and an air-permeable separating element to separate the solid aerosol-forming material in the first compartment and the liquid aerosol-forming material the second compartments. The first compartment is disposed downstream of the second compartment such that one or more constituents of the solid aerosol-forming material disposed within the first compartment is infused into the aerosol vapor generated in the second compartment during the passage of the aerosol vapor through the solid aerosol-forming material. The loosely packed solid particles are flexibly interconnected, thereby providing the design flexibility and simple manufacturing of the liquid retention element.

Description

Cartridge for aerosol-generating system

Technical field

The present invention relates to an electronic aerosol-generating system for producing an inhalable aerosol such as an electronic cigarette or e-cigarette, and more particularly, to an electronic aerosol-generating system that produces aerosol vapor by means of electrically generated heat. In particular, the invention relates to a cartridge for use in an aerosol-generating system comprising a solid aerosol-forming material and a liquid aerosol-forming material.

Description of related art Personal aerosol-generating systems also known as electronic cigarettes or e-cigarettes which generate aerosol without burning tobacco are considered an alternative to conventional combustion tobacco articles such as cigarettes, cigars, and pipes. The use of the electronic aerosol-generating systems widely spread due to the health concern related to a conventional smoking articles, such as generation of harmful chemical byproducts including carbonyls and carbon monoxide known to be associated with a combustion of a smoking article.

The personal aerosol-generating system is a battery-powered portable inhaler system, comprising a mouthpiece portion, a heating chamber to receive and to heat an aerosol forming material, a vaporizer unit, typically a heating element, a power supply unit and an electronic control unit. Vaporization occurs upon heating the aerosol-generating material up to a temperature same as or above the vaporizing temperature of the aerosol-forming material. One example of the conventional aerosol-generating systems may be configured to vaporize a liquid aerosol-forming material such as a nicotine containing liquid stored in a liquid store. The liquid store may be provided as a disposable part in the form of a cartridge which may further comprise a heating element. Alternatively, the liquid store may be non-detachably integrated in the aerosol- generating device where the liquid store is configured to be refillable once the aerosol forming material is depleted.

Aiming at providing users with an experience that simulates more closely the experience of consuming a cigarette, some devices combine the liquid aerosol-forming material with a solid aerosol forming material such as tobacco-based substrate to impart a tobacco taste to the aerosol to be inhaled. In such an aerosol-generating system, aerosol vapor generated from the liquid aerosol-forming material upon heating by a heating element is delivered through the solid aerosol forming material so that the aerosol from the solid aerosol forming material is entrained in the vapor. Such cartridge configuration is disclosed in for example EP3145349B1 , EP3145349B1 , and EP3554291A1. In the aerosol-generating systems described above, a cartridge stores liquid and solid aerosol-generating materials separately in first and second portions of a cartridge in order to avoid mixing these aerosol-generating materials in the cartridge. In such a cartridge, the compartment for storing a liquid aerosol forming material comprises a liquid retention element, such as a porous material typically a porous glass or ceramic, a foam, a sponge or a fibrous wicking material. At the same time, the compartment for storing a liquid aerosol-forming material is disposed at the upstream of the compartment for storing a solid aerosol-forming material in the cartridge such that aerosol vapor generated from the liquid aerosol-generating material is delivered through the solid aerosol-generating material to the mouthpiece air outlet. The cartridge may comprise a heating element to heat the liquid aerosol-forming material. The heating element may be integrated in the liquid retention element. Alternatively, the heating element may be a separate detachable element attached to the reusable part of the aerosol-generating system and may be inserted in the liquid retention element during use.

In such a case, the liquid retention element further comprises a cavity configured to receive the heater when the cartridge is inserted in the device, which may complicate the manufacturing process. Fabrication of the cavity in the porous materials may not be straightforward because the porous material can fracture under stress. The manufacturing process may also produce residual particulates which may give rise to safety concerns during the use of the electronic cigarette. The brittle nature of the porous material may further limit the design of a liquid retention element.

It may be desirable to provide a cartridge configuration which is simple and relatively easy to manufacture. It may be also desirable that the cartridge comprises less elements to be disposed or more reusable elements in order to reduce the environmental impact.

Summary of invention

According to a first aspect of the invention there is provided a cartridge for an aerosol generating system comprising a cartridge housing divided into a first compartment and a second compartment; the first compartment comprising a solid aerosol-forming material; the second compartment comprising a liquid aerosol-forming material, wherein the liquid aerosol-forming substrate comprises loosely-packed solid particles configured to retain an aerosol-forming liquid in the interstices of particles and/or on their surfaces; and an air-permeable separating element disposed between the first and the second compartments.

The liquid aerosol-forming substrate comprising loosely-packed solid particles absorbs liquid aerosol-generating material, resulting in formation of coagulated particles. In this way, the loosely-packed solid particles retain liquid aerosol-generating material at the interstices between adjacent particles and prevents for liquid from leaking into the first compartment. The liquid aerosol-generating material can be stored within the second compartment without mixing with the solid aerosol-generating material stored in the first compartment.

The air-permeable separating element disposed between the first and second compartments allows for the aerosol vapor generated from the liquid aerosol-generating material in the second compartment to be transported to the first compartment containing the solid aerosol-forming material through the air permeable element, while preventing the direct contact of the solid aerosol-generating material and liquid aerosol- generating material in the first and second compartments during storage and during utilization of the device.

In another aspect of the invention, an aerosol-generating system may comprise the cartridge; and an aerosol-generating device comprising: a cavity for receiving at least a portion of the cartridge; a heating device configured to heat at least a part of the liquid aerosol-forming material in the second compartment of the cartridge; a power supply; and a controller for controlling a supply of electrical power from the power supply to the heating element.

The heating device may comprise a heating element disposed in the cavity of the aerosol-generating device such that the heating device is located at a proximity of the first compartment of the device. In use, at least a portion of the first compartment is heated by the heating element to a temperature at or above the vaporization temperature of the liquid aerosol-generating material stored in the first compartment. In this way, the aerosol generated in the second compartment is subsequently infused by one or more constituents of the solid aerosol-forming material stored within the first compartment during the passage of aerosol vapor from the second compartment through the first compartment.

The heating device may be provided with an elongated heating element disposed in the distal end of the cavity of the aerosol-generating device. The elongated heating element may be a blade-shaped heating element. The blade-shaped heating element may be a resistive heating element. Alternatively, the heating element may be a susceptor element. The heating element is configured to penetrate a portion of the first compartment of the cartridge when the cartridge is inserted in the cavity of the aerosol generating device. In such a case, the cartridge may comprise a pierceable seal configured to be penetrated by the heating element when the cartridge is inserted in the device. The pierceable seal may extend across the upstream end of the cartridge. The heating element is preferably formed of titanium or stainless steels. Examples of other suitable materials include nickel-alloys, chromium-alloys, aluminum-alloys and iron-alloys.

In the liquid retention element comprising the loosely packed solid particles according to any embodiments of this invention, the cohesion of particles is brought about by the liquid on the surface which forms bridges between adjacent particles to connection them which allows for the loosely packed solid particles to have flexible interconnection among them. This allows for the particles comprising the liquid retention element to conform with the heating element inserted in the cartridge. During the insertion of the heating element by penetrating the pierceable seal attached to the cartridge, the loosely packed solid particles can rearrange their coordination to adapt to the shape of the heating element. This feature may reduce the complexity of manufacturing process, reduce the production cost and improve the versatility of the cartridge, compared to the use of a monolithic porous material which will require a cavity to accommodate the heating element.

The liquid retention element comprising loosely packed particles may also allow for reducing the risk to damage the liquid retention structure during the insertion of a heating element. Moreover, because the liquid retention structure can adapt to fit the shape of the heating element, the heat transfer of the heating element to e-liquid may be improved. Furthermore, this feature may be advantageous in terms of reusability of the cartridge materials compared to a liquid retention element formed of a monolithic porous material because loosely packed solid particles can be relatively easily decomposed for example by dispersing them into liquid. As described later, the individual disorganized particles can be cleaned using any established cleaning process for solid particles.

Alternatively, the cartridge may be configured to be inductively heated through induction. In this case, the aerosol-generating device comprises an induction coil which is configured to heat the second compartment of the cartridge inserted in the heating chamber of the aerosol-generating device. In the aerosol-generating system wherein the liquid aerosol-forming material is vaporized by induction heating, the second compartment may further comprise a susceptor element.

The susceptor element may comprises an inductively heatable material in the form of strips, discs, rings, plates, particles, flakes, and coils.

Suitable materials for the susceptor element may be ferromagnetic metals, alloys and oxides such as iron, nickel, cobalt, iron-alloys, nickel-alloys, cobalt-alloys, ferrites, or any other electrically conductive metals and alloys such as aluminum, stainless steels.

Preferably the susceptor element is embedded in the liquid aerosol-forming substrate for achieving an efficient thermal transfer. The susceptor element may comprise particles, flakes, strips, disks or like, mixed with the loosely packed solid particles of the liquid aerosol forming substrate.

Alternatively, the susceptor element may be disposed around at least a portion of the liquid aerosol-forming substrate. The housing of at least a part of the second compartment of the aerosol-generating may comprise a susceptor material.

The solid aerosol-forming material may comprise a tobacco or tobacco-derived material. The solid aerosol-forming material may comprise tobacco-containing beads, powder, shreds, strips, a reconstituted tobacco material, a cast tobacco sheet, or any combinations thereof. The air permeable separating element comprises one or more pores, holes, or air channels that are penetrating through the thickness of the air permeable separating element in order to maintain the solid aerosol-forming material in the first compartment and the liquid aerosol-forming material retained within the loosely-packed solid particles in the second compartment physically spaced out, while establishing the aerosol transfer between the first and second compartments. Preferably the air permeable separating membrane is a mesh, a perforated plates, film or foil, or an air-permeable membrane. Preferably the pores, holes, or air channels of the air permeable element are small enough to substantially block all individual particles of the loosely-packed particles in a liquid retention element.

The air permeable separating membrane may be stainless steels, titanium, thermal resistant polymers, PTFE, PEEK or any materials that is stable at the operation temperature of aerosol-generating system and chemically inert to the aerosol-forming materials stored in the cartridge and any chemical compounds generated by the aerosol-forming materials during use. In this way the liquid aerosol-generating material can be stored in the second compartment without experiencing any unintended chemical reactions. The loosely-packed solid particles comprise beads, flakes, fragments, fibers, or any combination thereof.

Preferably, the loosely-packed solid particles are stable at least up to a temperature for vaporization of the liquid aerosol-forming material. Preferably, at least the surfaces of the loosely-packed solid particles are thermally stable at least up to 350°C. Preferably, the loosely-packed solid particles or at least the surface of the loosely-packed solid particles comprises a material chemically inert to the liquid aerosol-forming material.

A chemically inert surface prevents the particles to take place in a chemical reaction or to possibly serve as catalyst to initialize an undesired chemical reaction during storage of the cartridge and during vaporization. The chemically inert surface may be a chemically inert surface of a solid particle itself. Alternatively, the chemically inert surface may be a chemically inert coating that encapsulates each solid particle. The chemical inertness is herein understood with respect to chemical substances stored in the cartridge as well as chemical substances generated during heating the aerosol forming substrates. The chemically inert coating as well as the particle should withstand at least up to a temperature for vaporization of the aerosol-forming material. Preferably, the loosely-packed solid particles comprise hydrophilic surface. In this way the liquid aerosol-generating material can be effectively retained in the interstices and the surfaces of particles.

The hydrophilic surface of particle may be a surface of a solid particle itself. Alternatively, the surface of the particles may be coated with hydrophilic coatings, or the surface of the particles may be grafted with a chemical compound comprising hydrophilic functional groups such as hydroxy groups, carboxy groups, carbonyl groups, amino groups, sulfhydryl groups, and phosphate groups.

The suitable materials for the loosely-packed solid particles may comprise silica, zeolite, glass or quartz, or any combination thereof.

Advantageously the surfaces of the particles may be porous such that the amount of liquid stored in the liquid retention structure can be increased.

Preferably, the loosely-packed solid particles comprise particles with maximum dimension at least equal or less than around 2 mm. For example, the maximum dimension of the beads may range from about 100 pm to about 1 mm, or they may range from about 200 pm to about 800 pm, preferably they may range from about 250 pm to about 600 pm. The maximum dimension is, for example, about 500 pm. The maximum dimension of the loosely-packed solid particles are substantially uniform. In this way, the size of interstices of adjacent particles are substantially uniform which causes a uniform transport of liquid by capillary force across the liquid retention element.

Advantageously, the cartridge comprising the loosely-packed solid particles to retain the liquid aerosol-forming material may be recyclable after use of the cartridge. Because the loosely-packed solid particles are not rigidly interconnected each other, the particles may be easily separated from the cartridge housing and the heating element and be decomposed into individual particles by, for example, dispersing them into liquid. The decomposed individual particles may be cleaned by any suitable method to clean particles and may be reused. Because conventional liquid retention materials such as a porous material, a micro fibrous material and a sponge that are in general not straightforward to clean due to their structural complication, the use of the loosely- packed solid particles may allow for a simple recycling process.

One of the example of the method of recycling of the cartridge comprises the steps of: separating the loosely-packed solid particles from a used cartridge; dispersing used particles in a suitable cleaning solution to remove residues of liquid aerosol-forming material; filtering to separate the particles from the cleaning solution; dispersing the particles in a rinsing solution; filtering to separate the particles from the rinsing solution; drying of the particles; and collecting of the particles for reuse. The cleaning method may further comprise a step of dry cleaning such as plasma cleaning and thermal cleaning. Optionally a hydrophilic treatment is carried out for the cleaned particles in order to improve the wettability for liquid aerosol-forming material.

Brief description of drawings

Embodiment of the invention are now described, by the way of example with reference to the drawings, in which;

Figure 1 shows a cross-sectional view of a cartridge in an embodiment of the invention.

Figure 2 shows a cross-sectional view of an aerosol-generating device configured to receive the cartridge shown in Figure 1.

Figure 3 shows a cross-sectional view of an aerosol generating system comprises the cartridge of Figure 1 received in the aerosol-generating device of Figure 2.

Figure 4 shows a cross-sectional view of a cartridge in another embodiment of the invention.

Figure 5 shows a cross-sectional view of an aerosol-generating device configured to receive the cartridge shown in Figure 4. Figure 6 shows a cross-sectional view of an aerosol generating system comprises the cartridge of Figure 4 received in the aerosol-generating device of Figure 5.

Figure 7 shows an example of a method of recycling the cartridge.

Detailed description with reference to drawings Figures 1 - 3 show an aerosol-generating system 1 comprising a cartridge 10 and an aerosol-generating device 30 according to an embodiment of the present invention. The cartridge is configured to be received in a heating chamber 35 of the aerosol-generating device 30. The cartridge 10 and the aerosol-generating device 30 can be detachably engaged in a functioning relationship. Various mechanisms may be used to connect the cartridge and the aerosol-generating device that include a threaded engagement, a press-fit engagement, an interference fit, a magnetic engagement, or the like. The aerosol delivery system 1 may be substantially rod-like shaped when the cartridge 10 and the aerosol-generating device 30 are assembled.

Figure 1 shows the cartridge 10 separated from the aerosol-generating device 30. The cartridge 10 comprises a cartridge housing 11 and an air permeable separating element 16 which divide the inner volume of the cartridge housing 11 into a first compartment 12 and a second compartment 13. The first compartment 12 is disposed at downstream of the second compartment 13 with reference to an airflow direction A. The first compartment 12 comprises a solid aerosol-forming substrate 20 and the second compartment 13 comprises a liquid aerosol-forming substrate 21.

The cartridge housing 11 comprises a tubular body 22, an upstream end 18 and a downstream end 17.

The downstream end 17 of the cartridge 10 may comprise a filter 15. The filter 15 retains the solid aerosol-forming substrate 20 in the cartridge housing 11. The filter may comprise a rod or plug of filter material such as cellulose acetate tow and polylactic acid fibers. The upstream end 18 of the cartridge housing 11 is a closed end. The closed end comprises a pierceable element 16. The pierceable element 16 is attached on the cartridge housing 11 such that the pierceable element 16 is penetrated by a heating element 32 of the aerosol-generating device 30 when the cartridge 10 is inserted in the heating chamber 35 of the aerosol-generating device 30.

The downstream end 17 of the cartridge housing 11 may comprise a mouthpiece 19 detachably attached to the downstream end 17 of the cartridge 10. The mouthpiece 19 defines at least one airflow channel comprising at least one air outlet. The air outlet is in fluid communication with air outlets of the cartridge through the filter 15 which may be integrated in the mouthpiece 19. Although the example in Figure 1 shows that the mouthpiece is attached on the distal end of the cartridge, the mouthpiece 19 may alternatively be detachably attached to a portion of the housing of the aerosol generating device 30 such that the mouthpiece covers the air outlet on the filter disposed at the downstream end of the cartridge. Alternatively, the mouthpiece 19 may be a part of the cartridge 10. In use, a user may draw the air from the mouthpiece to cause the air to flow into the aerosol generating system 1 from the air inlet of the aerosol generating device through the cartridge.

The air permeable separating element 14 is disposed within the inner volume of the tubular cartridge housing 11 to device the first compartment 12 and the second compartment 13. Preferably the air permeable element 14 is in a form of a disc. The diameter of the disc is similar to the inner diameter of the cartridge housing such that the air permeable separating element fits in the inner tubular body of the air permeable separating element. In this way, the first compartment 12 and the second compartment 13 are defined by the inner walls of the cartridge housing 11 and the surfaces of air permeable element 14. The air permeable separating element 14 may comprise a mesh or a perforated plate. The air permeable separating element may be positioned substantially perpendicular to the longitudinal axis of the cartridge body 200, wherein the separating element may provide for physical separation of the first compartment 12 and the second compartment 13 while, maintaining aerosol vapor communication therebetween. The first compartment 12 is positioned on the downstream side of the tubular body 22 of the cartridge and the second compartment 13 is positioned on the upstream side of the tubular body of the cartridge 10. The first compartment contains a solid aerosol-forming substrate 20 comprising a solid aerosol-forming material 23, while the second compartment contains a liquid aerosol-forming substrate 21 comprising a liquid retention element 25 and a liquid aerosol-forming material 27 stored in the liquid retention element 25. The liquid retention element 25 comprises loosely-packed solid particles 26.

The loosely-packed particles 26 are a granular material which is a conglomeration (or an aggregation) of small macroscopic solid particles. When the particles are wet by liquid, microscopic liquid bridges are formed in interstices of adjacent particles and the capillary force of the liquid bridges keeps the aggregated particles together. The network of particles is therefore flexible, and it is reorganizable when mechanical stress is applied. When a solid bulky element, for example a heater blade, is inserted in the agglomeration, the particles move to change the coordination to fit to the heater shape.

Preferably, the loosely-packed solid particles 26 comprise particles with maximum dimension at least equal or less than around 2 mm. For example, the maximum dimension of the beads may range from about 100 pm to about 1 mm, or they may range from about 200 pm to about 800 pm, preferably they may range from about 250 pm to about 600 pm. The maximum dimension is, for example, about 500 pm. The maximum dimension of the loosely-packed solid particles 26 are substantially uniform. In this way, the size of interstices of adjacent particles 26 are substantially uniform which causes a uniform transport of liquid by capillary force across the liquid retention element. With reference to the expression “maximum dimension”, in case of elongated particles like rods, for example, the maximum dimension is length of the rods. For particles with oval cross section, the maximum dimension is a large dimeter along the major axis. In case the particles are substantially spherical, the maximum dimension corresponds to the diameter. Preferably, the loosely-packed solid particles 26 are stable at least up to a temperature of vaporization of the liquid aerosol-forming material, for example up to 350°C.

In the context of the present description, a material is “stable” when that the material properties are unchanged or at least do not undergo any significant change. The material properties are, for example, phase (solid, liquid, gas), mechanical properties (strength, hardness etc.), crystal structure, and chemical properties (chemical compositions, chemical structure of constituents etc.).

Preferably, the loosely-packed solid particles 26 or at least the surface of the loosely- packed solid particles 26 comprises a material chemically inert to the liquid aerosol- forming material.

The chemically inert surface may be a chemically inert surface of a solid particle itself. Alternatively, the chemically inert surface may be a chemically inert coating that encapsulates each solid particle. The chemical inertness is herein understood with respect to chemical substances stored in the cartridge as well as chemical substances generated during heating the aerosol-forming substrates.

The chemically inert coating as well as the particle should withstand at least up to the temperature for vaporization of the aerosol-forming material 27.

The loosely-packed solid particles 26 are configured to retain an aerosol-forming liquid in the interstices of particles and their surfaces. In detail, as mentioned above, the particles are agglomerated together by the liquid bridges formed between the particles. This phenomenon in turn maintains the liquid in the agglomerated particle structure. The absorbing ability is related to the volume of liquid bridges formed in interstices of adjacent particles, which also determine the agglomeration force of particles.

The liquid aerosol-forming material 27 comprises an aerosol former. Suitable aerosol formers include polyhydric alcohols or mixtures thereof, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine. The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts and natural or artificial flavours. The liquid aerosol-forming material 27 comprises a tobacco-containing material comprising volatile tobacco flavour compounds which are released from the liquid upon heating. Preferably the liquid aerosol-forming substrate may comprise a non-tobacco material. The liquid aerosol-forming material 27 may be free from nicotine. Alternatively, the liquid aerosol-forming substrate may comprise nicotine.

The solid aerosol-forming material 23 of the solid aerosol-forming substrate 20 may comprise a tobacco or tobacco-derived material such as tobacco leaf or reconstituted tobacco in the form of granules, sheets, strips, shreds, pellets or any other form of tobacco material. The solid aerosol-forming substrate 20 may be an aerated tobacco mousse or an equivalent tobacco foam.

The solid aerosol-forming substrate 20 may comprise a non-tobacco material such as a flavorant in the form of granules, capsules, gel or any other forms of flavorant. The solid aerosol-forming substrate 20 may comprise tobacco-containing material and non tobacco containing material. In the context of the present description, the tobacco-containing material can be tobacco leaves, powdered tobacco plant, tobacco mousse, reconstituted tobacco material and any forms of tobacco material.

The solid aerosol-forming substrate 20 may include at least one aerosol-former. Suitable aerosol-formers include, but are not limited to: polyhydric alcohols, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine; 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. Preferred aerosol formers may comprise propylene glycol and glycerine.

Figure 2 shows the aerosol-generating device 30. The aerosol-generating device 30 comprises a housing 31 , a heating chamber 35 defined by housing 31 , a heating element 32, a power supply 33 and a controller 34. The heating chamber 35 is configured to receive at least a part of the second compartment 13 of the cartridge 10 by insertion of the cartridge 10 along the longitudinal axis of the aerosol-generating device 30. The heating element 32 is arranged at the bottom end 36 (or the distal end) of the heating chamber 35. The heating element 32 projects into the heating chamber 35. Preferably the heating element 32 is disposed in the substantially center of the cross-section of the heating chamber 35. The longitudinal axis of the heating element 32 may be aligned to the longitudinal axis of the aerosol-generating device 30. The housing 31 of the aerosol-generating device 30 further comprises at least one airflow inlet (not shown) in fluid communication with the air inlet channels of the cartridge 10.

In use, the upstream end portion of the cartridge 10 which corresponds to the portion of the second compartment 13 is inserted in the heating chamber 35 of the aerosol- generating device 30 as shown in Figure 3. Although, the housing 31 of the aerosol generating device 30 extend to cover the portion of the second compartment in the example illustrated in Figure 3, the housing may extend until at least a portion of the first compartment or it may extend to the downstream end 17 of the cartridge such that the cartridge is completely disposed within the heating chamber 35. During insertion of the cartridge 10, the pierceable element 16 on the cartridge 10 is penetrated by the heating element 32, allowing to insert the heating element 32 into the second compartment 13. The loosely-packed solid particles 26 instantly reorganize their arrangement to fit to the shape of the heating element when the heating element 32 is inserted in the liquid aerosol-forming substrate 21. When the cartridge 10 is completely inserted in the heating chamber 35, the heating element 32 is positioned within the second compartment 13. The length of the heating element 32 is shorter than the longitudinal length of the second compartment 32 of the cartridge 10 such that the heating element 32 inserted in the cartridge 10 does not extend beyond the second compartment 13. Preferably, the volume of the liquid aerosol-forming substrate 21 stored in the second compartment 13 is smaller than the inner cavity volume of the second compartment 13 such that the total volume of the liquid aerosol-forming substrate 21 and the inserted portion of the heating element 32 does not exceed the inner cavity volume of the second compartment 13 during and after insertion of the heating element into the cartridge.

Upon activation of the heating element 32, the liquid aerosol-forming substrate 21 comprising liquid aerosol-forming material 27 and loosely-packed particles 26 retaining the liquid aerosol-forming material 27 is heated to a temperature at or above the vaporization temperature of the liquid aerosol-forming material 27. The vapor generated in the second compartment 13 is subsequently mixed with air from the air inlet and delivered through the first compartment 12 to the air outlet of the filter 15. During the passage of the mixture of air and vapor through the solid aerosol-forming substrate 20 in the first compartment 12, the aerosol from the solid aerosol-forming substrate 20 is entrained in the mixture of air and vapor.

Figure 4 shows a cross-sectional view of a cartridge 40 in another embodiment of the invention. In this embodiment, the second compartment 43 of the cartridge 40 further comprises a susceptor element 44 which is configured to heat the liquid aerosol-forming substrate 21. The susceptor element 44 may comprises an inductively heatable material in the form of e.g. strips, discs, rings, plates, particles, flakes, and coils. Suitable materials for the susceptor element may be ferromagnetic metals, alloys and oxides such as iron, nickel, cobalt, iron-alloys, nickel-alloys, cobalt-alloys, ferrites, or any other electrically conductive metals and alloys such as aluminum, stainless steels. In this example, the susceptor element 44 comprises three ring-shaped susceptor plates 44a,

44b, 44c, but any number of susceptor pieces may be used and the type of susceptor may be any other form such as disks, strip, plates or a combination of thereof. Preferably the susceptor element 44 is embedded in the liquid aerosol-forming substrate 21 for achieving an efficient thermal transfer. The susceptor element may comprise particles, flakes, strips, disks or like, mixed with the loosely packed solid particles of the liquid aerosol forming substrate. Alternatively, the susceptor element may be disposed around at least a portion of the liquid aerosol-forming substrate. The housing of at least a part of the second compartment of the aerosol-generating may comprises a susceptor material. The cartridge housing 41 may comprises one or more air inlet channels (not shown) configured to deliver the air into the second compartment 43. The air inlet channels may be disposed in the tubular body of the cartridge housing 41.

Figure 5 shows the aerosol-generating device 50 configured to receive the cartridge 40 in Figure 4. The aerosol-generating device 50 comprises a heating chamber 55, an induction coil 52, a power supply 33 and a controller 34. The heating chamber 55 is configured to receive at least a part of the second compartment 43 of the cartridge 40 by insertion of the cartridge 40 along the longitudinal axis of the aerosol-generating device 50. The induction coil 52 is configured to transfer the energy to susceptor element 44 in the cartridge 40 by induction heating. The induction coil 52 is arranged such that the coil is disposed in the proximity of the second compartment 43 (the liquid aerosol-forming substrate 21) of the cartridge 40 when the cartridge 40 is inserted in the heating chamber 55. The induction coil 52 may be embedded in the housing 51 , typically the tubular side wall portion of the heating chamber 55. In this example, the induction coil extends from the upstream end of the second compartment to the downstream end the second compartment. The housing 51 of the aerosol-generating device 50 further comprises an airflow inlet (not shown) which is in fluid communication with the air inlet channels of the cartridge 40.

In use, the second compartment 43 of the cartridge 40 is inserted in the heating chamber 55 of the aerosol-generating device 50 as shown in Figure 6. When the cartridge 40 is completely inserted in the heating chamber 55, the induction coil 52 surrounds at least a portion of the liquid aerosol-forming substrate 21 in the second compartment 55 of the cartridge 50.

Upon activation of the induction coil 52, the electrical power from the power supply 33 is delivered to the induction coil. The controller 34 controls the delivery of the electrical power to the induction coil 52 at a frequency to allow for the induction coil 52 to generate an electromagnetic field to heat up the susceptor element 44 at or above a target temperature. Upon heating of the susceptor element 44, at least a portion of the liquid aerosol-forming substrate is heated at or above a temperature to vaporize the liquid aerosol-forming material stored in the liquid aerosol-forming substrate 21. The vapor generated in the second compartment 43 is then mixed with air flowing through the cartridge 40. The mixture of vapor from the liquid aerosol-forming substrate 21 and air is subsequently transferred through the air-permeable separating element 14 to the first compartment 42. During the passage of the mixture of air and aerosol vapor through the solid aerosol-forming substrate 20 in the first compartment, the aerosol from the solid aerosol-forming substrate 20 is entrained in the mixture of air and aerosol vapor. The mixture of air and aerosol vapor is delivered through the first compartment 42 to the air outlet on the downstream end 47 of the cartridge 40 through the filter 15. Because the loosely-packed solid particles in the liquid aerosol-forming substrate are not rigidly interconnected, they may be separated by, for example, dispersing them into a liquid. This may be advantageous in terms of reusability of the cartridge because individually separated particles can be effectively cleaned by any cleaning methods established for small particles. Figure 7 illustrates an example of a method of recycling the cartridge comprising the loosely-packed solid particles according to an embodiment. The method described below is intended to be illustrative only and the methods may comprise alternative steps or one or more additional steps.

At step 60, the cartridge after use is provided. Then, the loosely packed solid particles forming the liquid retention structure may be removed from the cartridge housing and collected in a container comprising filtering element (step 61). The container may be a basket comprising metal mesh, metal wire or plastic mesh.

The loosely-packed solid particles in the container are subsequently cleaned in a cleaning liquid (step 62). The particles are immersed and dispersed in a suitable cleaning solution to remove residues of liquid aerosol-forming material and any chemical compounds produced during use of the cartridge.

Subsequently, the container containing the particles is removed from the cleaning liquid, and it is brought in a rinsing solution (Step 64) in order to remove the residual cleaning solution on the particles. The steps of cleaning and rinsing may be repeated. These steps may be performed by combining with ultrasonic vibration.

Afterwards the particles are dried (Step 65). The cleaning method may further comprise one or more additional steps of dry-cleaning process such as plasma cleaning or thermal cleaning or combination of thereof. Optionally a hydrophilic treatment may be carried out for the cleaned particles in order to improve the wettability for e-liquid.

Claims

1. A cartridge for an aerosol-generating system comprising: a cartridge housing divided into a first compartment and a second compartment; the first compartment comprising a solid aerosol-forming material; the second compartment comprising a liquid aerosol-forming substrate, wherein the liquid aerosol-forming substrate comprises a liquid retention structure comprising loosely-packed solid particles configured to retain a liquid aerosol forming material in the interstices of particles and/or on their surfaces; and an air-permeable separating element disposed between the first and the second compartments.

2. A cartridge according to claim 1, wherein the solid aerosol-forming material comprises a tobacco or tobacco-derived material.

3. A cartridge according to claim 1 , wherein the air-permeable separating element is a mesh, a perforated plates, film or foil, or an air-permeable membrane configured to maintain the solid aerosol-forming material in the first compartment and the liquid aerosol-forming material retained within the loosely-packed solid particles in the second compartment physically spaced out, while establishing the aerosol transfer between the first and second compartments.

4. A cartridge according to any one of preceding claims, wherein at least the surfaces of the loosely-packed solid particles are stable at least up to a temperature for vaporization of the liquid aerosol-forming material.

5. A cartridge according to claim 4, wherein at least the surfaces of the loosely-packed solid particles are thermally stable at least up to 350°C.

6. A cartridge according to any one of preceding claims, wherein the loosely-packed solid particles or at least the surface of the loosely-packed solid particles comprises a material chemically inert to the liquid aerosol-forming material.

7. A cartridge according to any one of preceding claims, wherein the loosely-packed solid particles comprise beads, flakes, fragments, fibers, or any combination thereof.

8. A cartridge according to any one of preceding claims, wherein the loosely-packed solid particles comprise hydrophilic surfaces.

9. A cartridge according to any one of preceding claims, wherein the loosely-packed solid particles comprise silica, zeolite, glass or quartz, or any combination thereof.

10. A cartridge according to any one of preceding claims, wherein the loosely-packed solid particles comprise particles with maximum dimension at least equal to or less than around 2 mm.

11. A cartridge according to any one of preceding claims, wherein the cartridge comprises a pierceable seal disposed on the cartridge housing of the second compartment.

12. A cartridge according to any one of claims 1-9, where in the second compartment comprises an inductively heatable susceptor element which can be heated through induction.

13. An aerosol-generating system comprising: a cartridge according to any one of preceding claims; and an aerosol-generating device comprising: a cavity for receiving at least a portion of the cartridge; a heating device configured to heat at least a part of the liquid aerosol-forming in the second compartment of the cartridge; and a power supply; and a controller for controlling a supply of electrical power from the power supply to the heating element.

14. An aerosol-generating system according to claim 13, wherein the heating device comprises an elongated heater configured to pierce the pierceable seal and to be inserted in the second compartment when the cartridge is received in the cavity of the aerosol-generating device.

15. An aerosol-generating system according to any one of preceding claims, wherein the heating device of the aerosol-generating device comprises an induction coil in the proximity of the second compartment of the cartridge when the cartridge is received in the cavity of the aerosol-generating device.