Filter element with granules distributed between fragments of foam

Abstract

The invention relates to a filter element for an aerosol-generating article. The filter element comprises a filtration material. The filtration material comprises a plurality of granules comprising an active material. The filtration material comprises a plurality of discrete fragments of foam of cellulosic material. The granules are distributed between the discrete fragments of foam.

Description

[0001] FILTER ELEMENT WITH GRANULES DISTRIBUTED BETWEEN FRAGMENTS OF FOAM

[0002] The present invention relates to a filter element for an aerosol-generating article. The present invention relates to a method for manufacturing a filtration material for the filter element. The present invention relates to an aerosol-generating article. The present invention relates to an aerosol-generating system.

[0003] It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate are volatilised without burning the aerosolforming substrate. Aerosol-forming substrate may be provided as part of an aerosol-generating article. The aerosol-generating article may have a rod shape for insertion of the aerosolgenerating article into a cavity, such as a heating chamber, of the aerosol-generating device. A heating element may be arranged in or around the heating chamber for heating the aerosolforming substrate once the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device. The article may comprise a filter element. The filter element may comprise a plastic material, such as cellulose acetate tow.

[0004] It would be desirable to provide a filter element offering improved sustainability. It would be desirable to provide a filter element with reduced environmental impact. It would be desirable to provide a filter element of reduced dimensions. It would be desirable to provide a filter element having improved filtration properties. It would be desirable to provide a filter element having improved filtration efficiency. It would be desirable to provide a filter element with tuneable filtration properties. It would be desirable to provide a filter element which can be cost efficiently produced. It would be desirable to provide a filter element with tuneable airflow properties. It would be desirable to provide a filter element with improved airflow properties. It would be desirable to provide a filter element providing an improved user experience. It would be desirable to provide a filter element having an improved flavor delivery. It would be desirable to provide a replacement for cellulose acetate filters.

[0005] According to an embodiment of the invention there is provided a filter element for an aerosol-generating article. The filter element may comprise a filtration material. The filtration material may comprise a plurality of granules. The plurality of granules may comprise an active material. The filtration material may comprise a plurality of discrete fragments of foam of cellulosic material. The granules may be distributed between the discrete fragments of foam.

[0006] According to an embodiment of the invention there is provided a filter element for an aerosol-generating article. The filter element comprises a filtration material. The filtration material comprises a plurality of granules comprising an active material. The filtration material comprises a plurality of discrete fragments of foam of cellulosic material. The granules are distributed between the discrete fragments of foam.

[0007] The filter element may offer improved sustainability. The filter element may have a reduced environmental impact. The filter element may be of reduced dimensions. The filter element may have improved filtration properties. The filter element may have improved filtration efficiency. The filter element may have tuneable filtration properties. The filter element may be cost efficiently produced. The filter element may have tuneable airflow properties. The filter element may have improved airflow properties. The filter element may have tuneable aerosol flow properties. The filter element may have improved aerosol flow properties. The filter element may provide an improved user experience. The filter element may have an improved flavor delivery. The filter element may be a replacement for cellulose acetate filters. The filter element may be configured to replace cellulose acetate filters in aerosol-generating articles.

[0008] The granules being distributed between the discrete fragments of foam may relate to the granules being arranged between the discrete fragments of foam.

[0009] The fragments of foam of cellulosic material may be essentially free of granules comprising active material.

[0010] The filtration material may comprise a body formed from the plurality of discrete fragments of foam of cellulosic material.

[0011] The foam may be porous. The foam may be a dry foam. The foam may be a solid foam. A dry foam may refer to a material formed from pockets filled with air or other gas in a solid. A dry foam may refer to a material that has been formed from a wet foam by drying the wet foam.

[0012] A wet foam may refer to a material formed from pockets of air or other gas in a liquid.

[0013] A material having a closed-cell configuration may refer to a material comprising fluidly separated pockets of air or other gas in a solid. The material having a closed-cell configuration may comprise pockets arranged on the surface of the material which are fluidly connected to the surroundings of the material. A material having an open-cell structure may refer to a material comprising fluidly interconnected pockets of air or other gas in a solid.

[0014] The foam may be produced by preparing a wet foam from a dispersion and removing the liquid dispersion medium. The dispersion may be a dispersion of cellulosic material in a liquid dispersion medium. The dispersion may be a dispersion of regenerated cellulose. The wet foam may be produced from the dispersion by agitating the dispersion or otherwise introducing bubbles of air into the dispersion. The dispersion medium may be removed by evaporation, freeze drying or supercritical drying.

[0015] “Pore” may refer to a pocket filled with air or other gas which is defined by a wall at least partially surrounding the pocket. A “diameter” of the pore may be a distance across the pocket between the wall at least partially surrounding the pocket. A “diameter” of the pore may be the shortest distance across the pocket between the wall at least partially surrounding the pocket. Pores may be arranged on a surface of a material. Pores may be arranged within a material. A porous material may comprise pores.

[0016] “Porosity" may refer to the volume fraction of void space in a material or component. “Porosity" may refer to the volume fraction of void space in the foam. For example, if 60% of a volume of the foam were unfilled by solid material, the foam would have a porosity of 0.6. “Porosity" may refer to the volume fraction of void space in filter element. Porosity" may refer to the volume fraction of void space in granule.

[0017] The foam may be biodegradable. The foam may be recyclable.

[0018] The granules may be dispersed between the discrete fragments of foam. The granules may be arranged between the discrete fragments of foam. The granules may be sandwiched between the discrete fragments of foam. The granules may be trapped between the discrete fragments of foam. The granules may be immobilized between the discrete fragments of foam.

[0019] Preferably, the granules are arranged between the discrete fragments of foam.

[0020] The filtration material may have a cylindrical shape. The filtration material may have a solid cylindrical shape. The filtration material may be a rod. The filtration material may cuboidshaped.

[0021] The body of discrete fragments of foam may be configured as a solid cylindrical rod. The granules may be distributed in the solid cylindrical rod of discrete fragments of foam. The granules may be dispersed in the solid cylindrical rod of discrete fragments of foam. The body of discrete fragments of foam may be configured as a solid cube. The granules may be distributed in the solid cube of discrete fragments of foam. The granules may be dispersed in the solid cube of discrete fragments of foam. The shape of the body of the discrete fragments of foam may facilitated by the filter element wrapper discussed below. The filter element wrapper discussed below may be tightened around the discrete fragments of foam.

[0022] The discrete fragments of foam may have an irregular shape. The discrete fragments of foam may be irregularly packed. The discrete fragments of foam may have complementary shapes. The discrete fragments of foam may have substantially the same size.

[0023] The discrete fragments of foam may be configured to at least partially abut one or more other fragments of foam. The discrete fragments of foam may be configured to at least partially abut one or more adjacent fragments of foam. The discrete fragments of foam may be configured to contact one or more other discrete fragments of foam. The discrete fragments of foam may be configured to contact one or more adjacent discrete fragments of foam.

[0024] The discrete fragments of foam may be configured such that spaces are formed between the discrete fragments of foam. The discrete fragments of foam may be configured such that air flow channels are formed between the discrete fragments of foam. The spaces may be filled with air. The spaces may be filled with aerosol being pulled into the filtration material by the draw of a user. The spaces may be formed between the discrete fragments of foam. The spaces may be formed between adjacent fragments of foam. The spaces may be formed between outer surfaces of adjacent discrete fragments of foam. Air flow channels may be formed between the discrete fragments of foam. At least some of the spaces between the discrete fragments of foam may be fluidly connected to each other. At least some of the spaces between the discrete fragments of foam may be fluidly interconnected. The spaces between the discrete fragments of foam may form a fluidly interconnected network. The spaces between the discrete fragments of foam may form a branched network. The granules may be distributed in the spaces between the discrete fragments of foam. The granules may be dispersed in the spaces between the discrete fragments of foam. The granules may be arranged in the spaces between the discrete fragments of foam. The granules may be distributed in the air flow channels between the discrete fragments of foam. In use, aerosol pulled into the filtration material by the draw of user may at least partially flow through the spaces between the discrete fragments of foam.

[0025] The discrete fragment of foam may have a boundary. The granules may be distributed between the boundaries of the discrete fragments of foam. The spaces between the discrete fragments of foam may be defined by the boundaries of the discrete fragments of foam.

[0026] Each of the discrete fragments of foam may have a boundary. The granules may be distributed between the boundaries of the discrete fragments of foam.

[0027] The discrete fragments of foam may be configured as a matrix for the granules. The discrete fragments of foam may form a core of the filter element.

[0028] The discrete fragments of foam may be derived from a larger entity. The fragments of foam may be obtained by fragmenting a sheet of the foam. The fragments of foam may be obtained by tearing pieces off a sheet of the foam. The fragments may be obtained by randomly tearing pieces off a sheet of foam.

[0029] The filtration material of the filter element may comprise at least 10 discrete fragments of foam. The filtration material of the filter element may comprise at least 25 discrete fragments of foam. The filtration material of the filter element may comprise at least 50 discrete fragments of foam.

[0030] The filter element may comprise a proximal end. The filter element may comprise a distal end. The filtration material may be arranged between the proximal end of the filter element and the distal end of the filter element. The proximal end of the filter element and the distal end of the filter element may be fluidly connected via the filtration material. The proximal end of the filter element and the distal end of the filter element may be fluidly connected via the body of the discrete fragments of foam. The filtration material may extend between the proximal end of the filter element and the distal end of the filter element. The body of the discrete fragments of foam may extend between the proximal end of the filter element and the distal end of the filter element.

[0031] The granules may be porous. The granules may be made from a porous material. The granules may have an open-cell structure. The granules may have a closed-cell structure. The granules may be non-porous.

[0032] The granules may be derived from a larger entity. The granules may be obtained by fragmenting a rock material. The granules may comprise a solid. The granules may be made from a solid material. The granules may have a regular shape. The granules may have a substantially spherical shape. The granules may have an irregular shape. The granules may be of macroscopic size.

[0033] The size of the granule may be smaller than the size of the discrete fragment of foam. The volume of the granule may be smaller than the volume of the discrete fragment of foam. The granules may be configured to be arranged between the discrete fragments of foam. The granules may be enclosed between the discrete fragments of foam. The granules may be configured to abut the discrete fragments of foam. The granules may be configured to be in contact with the discrete fragments of foam. The granules may be arranged in spaces between the discrete fragments of foam. The granules may be embedded between the discrete fragments of foam. The granules may be arranged in spaces formed along the contact areas of the discrete fragments of foam. The granules may be configured to be fluidly connected to one or more of the discrete fragments of foam. The granules may be configured to be fluidly connected to one or more of the spaces between the discrete fragments of foam.

[0034] The discrete fragments of foam may be configured such that spaces are formed between the discrete fragments of foam. The granules may be distributed in the spaces between the discrete fragments of foam.

[0035] The granules may consist of the active material. The granules may be made of the active material. The granules may be impregnated with the active material. The granules may be coated with the active material. The active material may be applied to the granules. The active material may be applied to a surface of the granules. The active material may be arranged in pores of the granule.

[0036] The active material may be configured to adjust characteristics of an aerosol. The active material may be activated charcoal. The active material may be configured to remove undesirable compounds from an air flow or aerosol flow. The active material may be a volatile active material. The active material may be a flavoring material. The active material may be a flavorant. The active material may be configured to flavor an aerosol pulled through the filter element.

[0037] The foam be porous. The foam may be an open-cell foam. The granules may be porous. A porosity of the foam may be different to a porosity of the granules. A density of the foam may be different to a density of the granules.

[0038] The overall air flow or aerosol flow may be a combination of the flow through and around the discrete fragments of foam and the granules. Air or aerosol may flow through the discrete fragments of the foam. Air or aerosol may flow through the granules. Air or aerosol may flow through spaces formed between the discrete fragments of foam. Air or aerosol may flow around the discrete fragments of foam. Air or aerosol may flow around the granules.

[0039] The air flow or aerosol flow in the filtration material may be predominantly directed parallel to a longitudinal axis of the filter element. The air flow or aerosol flow through the discrete fragments of foam may be predominantly directed parallel to a longitudinal axis of the filter element. The air flow or aerosol flow around the discrete fragments of foam may be predominantly directed parallel to a longitudinal axis of the filter element. The flow predominantly directed parallel to the longitudinal axis of the filter element may be deviated by the granules. The flow predominantly directed parallel to the longitudinal axis of the filter element may be deviated around the granules. The granules may be configured to define a turbulent flow. The turbulent airflow may at least partially be defined by the porosity of the granules. The turbulent airflow may at least partially be defined by the size and shape of the granules.

[0040] The turbulent airflow may result in a given volume of aerosol remaining at the granule for an increased amount of time. The turbulent airflow may result in a given volume of aerosol interacting with the granule for an increased amount of time. The turbulent airflow may result in a given volume of aerosol flowing through the granule multiple times. The turbulent airflow may result in an improved filtering efficiency by the granule. The turbulent airflow may result in an improved flavoring of the aerosol.

[0041] The filter element may provide an adjustable air flow management. The properties of the air flow or aerosol flow in the filter element may be tuned by varying, amongst others, one or more of the characteristics of the foam, the configuration of the foam, the porosity of the foam, the density of the foam, the size of the discrete fragments of foam, the shape of the discrete fragments of foam, the characteristics of the granules, the configuration of the granules, the material from which the granules are made, the porosity of the granules, the density of the granules, the volume fraction of the granules in the filtration material, the distribution of the granules in the body of discrete fragments of foam, the size distribution of the granules, the size of the granules, the shape of the granules, and the configuration of the spaces between the discrete fragments of foam. The flow may be predominantly through the discrete fragments of foam and the spaces formed between the fragments of foam. The filtration performance of the filter element may be adjusted by adjusting the air flow or aerosol flow in the filter element.

[0042] The filtration performance of the filter element may be tuned by the configuration of the of the foam and the granules. The filtration performance of the foam may be different to the filtration performance of the granules. The foam may provide a different filtration profile than the granules. For example, a first undesired compound may predominantly be removed from the aerosol by the foam and a second undesired compound may predominantly be removed from the aerosol by the granules.

[0043] The resistance-to-draw of the filter element may be tuned by varying, amongst others, one or more of the characteristics of the foam, the configuration of the foam, the porosity of the foam, the density of the foam, the size of the discrete fragments of foam, the shape of the discrete fragments of foam, the characteristics of the granules, the configuration of the granules, the porosity of the granules, the density of the granules, the volume fraction of the granules in the filtration material, the distribution of the granules in the body of discrete fragments of foam, the size distribution of the granules, the size of the granules, the shape of the granules, and the configuration of the spaces between the discrete fragments of foam.

[0044] A porosity of the filter element may influence the resistance-to-draw of the filter element. A porosity of the filtration material may influence the resistance-to-draw of the filter element. A porosity of the filtration material may be influenced by one or more of a porosity of the foam, a porosity of the granules and a compression force exerted on the filtration material. The compression force may be exerted by a tipping paper or filter element wrapper discussed below circumscribing the filtration material.

[0045] The properties of the filter element may be adjusted in dependence on the characteristics of an aerosol-generating article into which filter element is incorporated. The resistance-to-draw of the filter element may be adjusted in dependence of the characteristics of the aerosol-generating article into which filter element is incorporated.

[0046] The resistance-to-draw may be determined by the porosity of the filter element. The resistance-to-draw may be substantially determined by the porosity of the filtration material. The resistance-to-draw of an aerosol-generating article comprising the filter element as described herein may be determined by the porosity of the filter element.

[0047] The filtration material my consist of the plurality of granules and the plurality of discrete fragments of foam.

[0048] The filtration material may be free of cellulose acetate. The filter element may be free of cellulose acetate. The foam may be free of cellulose acetate. The granules may be free of cellulose acetate.

[0049] The foam may be a porous foamed cellulosic material. The cellulosic material may be regenerated cellulose.

[0050] The foam may be a regenerated cellulose foam. The regenerated cellulose material may be free of cellulose acetate. The foam may comprise the regenerated cellulose material. The foam may consist of a regenerated cellulose material. The regenerated cellulose material may comprise regenerated cellulose fibers. The foam may comprise regenerated cellulose fibres. The foam may be made of regenerated cellulose fibres. The discrete fragments of foam may be made from foamed regenerated cellulose. The discrete fragments of foam may be made from non-woven structures of regenerated cellulosic fibers.

[0051] The regenerated cellulose fibres may be obtained by dissolving pure cellulose from one or both of wood pulp and plant fibres. The regenerated cellulose fibres may be obtained by dissolving derivative cellulose from one or both of wood pulp and plant fibres.

[0052] The regenerated cellulose fibers may have a uniform length. A length of the regenerated cellulose fibers may be homogenised. A length of the regenerated cellulose fibers may be homogenised using continuous spinning and a regenerating technique. The cellulosic material from which the regenerated cellulose fibers are derived may be obtained from recycling materials.

[0053] Homogenization of the length of the regenerated cellulose fibers may be achieved by preparing and dissolving intermediate compounds, such as sodium xanthate or acetate derivatives, along with the regeneration of the fibers. Derivatization of the cellulose fibers may improve the solubility of the the fibers in a solvent. The solvent may be aqueous or nonaqueous. The cellulose structure may be transformed depending on the type of solvent, treatment conditions and the type of fibers to be obtained.

[0054] The foam may be regenerated cellulose material tow. The foam may be regenerated cellulose fiber tow. The foam may comprise bundles of regenerated cellulose fibers.

[0055] The foam may have a density of between 15 kg / m3and 45 kg / m3, preferably of between 20 kg / m3and 40 kg / m3. The density of the foam may be determined according to ISO 845.

[0056] The foam may have a paper mass content of between 70 weight-% and 95 weight-%, preferably of between 75 weight-% and 90 weight-%.

[0057] The foam may comprise a biopolymer in an amount of between 10 weight-% and 25 weight %, preferably of between 15 weight-% and 20 weight-%. The biopolymer may comprise a polyhydroxyalkanoate (PHA). The polyhydroxyalkanoate may be polyhydroxy butyrate. The foam may comprise a polyhydroxyalkanoate in an amount of between 10 weight-% and 25 weight %, preferably of between 15 weight-% and 20 weight-%. The foam may comprise a polyhydroxy butyrate in an amount of between 10 weight-% and 25 weight %, preferably of between 15 weight-% and 20 weight-%.

[0058] The foam may comprise a biodegradable thermoplastic. The foam may be made from a biodegradable thermoplastic. Polyhydroxy butyrate (PHB) may be produced from sugar or from carbon dioxide using cyanobacteria.

[0059] The discrete fragments of foam may be obtained by fragmentation of a sheet of foam. An indentation force deflection (IFD) test value may be determined according ASTM D 3574. The characterization according to ASTM D 3574 may be carried out using 65 % feed. The indentation force deflection (IFD) test value of the sheet of foam may be of between 380 Newton and 570 Newton, preferably of between 410 Newton and 500 Newton. A hardness may be determined according to ISO 2439 Method B. The hardness of the sheet of foam may be of between 75 Newton and 105 Newton, preferably of between 80 Newton and 100 Newton. A compression set value may be determined according to ISO 1856 Method C1. The compression set value may be determined after 2.5 hours. The compression set value of the sheet of foam may be of between 20 percent and 40 percent, preferably of between 25 percent and 35 percent. A thermal conductivity may be determined according to ISO 8302. The thermal conductivity of the sheet of foamed porous material may be of between 0.025 W / mK and 0.05 W / mK, preferably of between 0.03 W / mK and 0.04 W / mK.

[0060] The sheet of foam may be fragmented to obtain a desired granulometry. The sheet of porous found material may be shredded to obtain the discrete fragments of foam.

[0061] The foam may be based on one or more of a wood pulp, a bamboo pulp, pulps obtained from tobacco stems, and hybrid forms of nanocellulose and kaolin-microfibrillated cellulose composites.

[0062] The foam may be a biocomposite foam. The foam may be a nanocellulose-based foam. The foam may be a hybrid foam. The foam may be a hybrid foam of nanocellulose and kaolin- microfibrillated cellulose composites. The foam may be a polyhydroxyalkanoate-based foam. The foam may be a foam based on polyhydroxy butyrate. The foam may be a dry foam. The foam may be a solid foam.

[0063] The foam of cellulosic material may be a foamed cellulosic material. The foam of cellulosic material may be a foam of cellulosic material. The foam of cellulosic material may be manufactured according the method of manufacturing a sheet of foamed cellulosic material as described in European patent application 23206185.3, which is herewith incorporated by reference. The foam of cellulosic material may be the filtration material used in the aerosolgenerating article disclosed in European patent application 23206185.3, which is herewith incorporated by reference. The foam of cellulosic material may be the foamed cellulosic material used in the aerosol-generating article disclosed in European patent application 23206185.3, which is herewith incorporated by reference. A sheet of the foamed cellulosic material may be manufactured using a method comprising the following steps: a) preparing a suspension of cellulosic material, wherein the suspension comprises a foaming agent, b) agitating the suspension of cellulosic material and, optionally, adding hydrophobizing agent to the suspension of cellulosic material to obtain a wet foam of cellulosic material, c) preparing a sheet of the wet foam of cellulosic material and dewatering the sheet of wet foam of cellulose material, d) drying the sheet of wet foam of cellulosic material, e) rewetting the sheet of foam f) adjusting a thickness of the sheet of foam, and g) drying of the foam.

[0064] The method may yield a sheet of dry foamed cellulosic material. The method may yield a sheet of dry foam of cellulosic material.

[0065] The suspension of cellulosic material may be a suspension of pulp. The suspension of cellulosic material may be a suspension of wood pulp. The suspension of cellulosic material may be a suspension of cellulose. The suspension of cellulosic material may be a suspension of refined cellulose. The suspension of cellulosic material may be a suspension of cellulosic fibers. The suspension of cellulosic material may be a suspension of cellulose fibers.

[0066] The cellulosic material may be cellulose. The cellulosic material may be cellulosic fibers. The cellulosic material may be cellulose fibers. The cellulosic material may comprise cellulose. The cellulosic material may comprise cellulosic fibers. The cellulosic material may comprise cellulose fibers. The cellulosic material may be free of cellulose acetate.

[0067] The cellulosic material may be based on one of bleached softwood pulp, unbleached softwood pulp, bleached eucalyptus pulp and bleached cotton linter pulp, or any combinations thereof. The cellulosic material may be derived from one of bleached softwood pulp, unbleached softwood pulp, bleached eucalyptus pulp and bleached cotton linter pulp, or any combinations thereof.

[0068] The foaming agent may comprise one or more surfactants. Preferably, the foaming agent may be a mixture comprising sodium dodecyl sulphate (SDS) in an amount of about 80 mol-% and polyoxyethylene (20) sorbitan monolaurate in an amount of about 20 mol-%.

[0069] Preferably, the hydrophobizing agent may be alkyl ketene dimer (AKD). The hydrophobizing agent may be added to the suspension of cellulosic material at an amount of about 1 weight-% of the suspension.

[0070] In step a), the cellulosic material may be refined to between 2 percent and 3 percent. In step a), the conductivity of the suspension of cellulosic material may be adjusted to 1000 pS / cm by adding sodium chloride. In step a), the pH of the suspension of cellulosic material may be adjusted to about 8 by adding sodium hydroxide. In step a), a strength additive may be added to the suspension of cellulosic material. The strength additive may be selected from one or more of sodium carboxymethlycellulose (CMC), microfibrillated cellulose and cellulose nanofibrils.

[0071] In step c), the wet foam of cellulosic material may be poured on a hand sheet mould. In step c), the sheet of wet foam of cellulosic material may drained by gravity. In step c), the dewatering may not be performed using a vacuum. In step c), a fabric may arrange on top of the foam to stabilize the foam. In step d) the drying may be performed in an oven at 70 degrees Celsius.

[0072] In step e), the foam may be rewetted to 50 percent moisture content. In step e), the sheet of foam may be rewetted by exposing the sheet to an atmosphere having 50 % moisture content for 4 hours.

[0073] In step g), the foam may be dried in an oven at 70 degrees Celsius. In step g), the foam may be cured at about 80 degrees Celsius for 2 hours to ensure complete reaction of AKD.

[0074] The foamed cellulosic material may be a foam of cellulosic material. The foamed cellulosic material may be a dry foam of cellulosic material. The foamed cellulosic material may be a solid foam of cellulosic material. The foamed cellulosic material may be an open-cell foam. The foamed cellulosic material may be free of cellulose acetate. The foamed cellulosic material may be porous. A density of the foam of cellulosic material may be of between 45 kg / m3and 105 kg / m3.

[0075] The granules may be homogeneously distributed between the discrete fragments of foam.

[0076] The granules may be homogeneously distributed within the body of the discrete fragments of foam. The granules may be homogeneously distributed between the discrete fragments of foam throughout the body of the discrete fragments of foam. The granules may be homogeneously dispersed between the discrete fragments of foam. The granules may be homogeneously dispersed between the discrete fragments of foam throughout the body of the discrete fragments of foam. The granules may be homogeneously distributed in the spaces between the discrete fragments of foam. The granules may be homogeneously dispersed in the spaces between the discrete fragments of foam. The granules may be homogeneously distributed throughout the spaces between the discrete fragments of foam. The granules may be homogeneously arranged throughout the spaces between the discrete fragments of foam.

[0077] The filter element may be cylindrically shaped. The filter element may be a rod.

[0078] The filter element may have a solid cylindrical shape. The filter element may be cuboidshaped. The fragments of foam may be cylindrically arranged. The fragments of foam may be cubically arranged. The body of the discrete fragments of foam may be cylindrically shaped. The body of the discrete fragments of foam may have a solid cylindrical shape. The body of the discrete fragments of foam may be cuboid-shaped. The filter element may have a substantially circular cross-section. The filter element may have a skewed circular crosssection. The filter element may have a rectangular cross-section. The body of the discrete fragments of foam may have a substantially circular cross-section. The body of the discrete fragments of foam may have a skewed circular cross-section. The body of the discrete fragments of foam may have a rectangular cross-section. The filtration material may have a cylindrical shape. The filtration material may have a substantially circular cross-section. The filtration material may have a skewed circular cross-section. The filtration material may have a rectangular cross-section.

[0079] The filter element may comprise a filter element wrapper configured to at least partially circumscribe the filtration material. The filter element may comprise a filter element wrapper configured to fully circumscribe the filtration material.

[0080] The filter element wrapper may at least partially circumscribe the discrete fragments of foam. The filter element wrapper may fully circumscribe the discrete fragments of foam. The filter element wrapper may circumscribe the discrete fragments of foam. The filter element wrapper may be wrapped around the filtration material. The filter element wrapper may be wrapped around the discrete fragments of foam. The filter element wrapper may be wrapped around the body of the discrete fragments of foam. The filter element wrapper may be wrapped around the rod-shaped body of the discrete fragments of foam. The filter element wrapper may have substantially the same length as the body of discrete fragments of foam.

[0081] The filter element wrapper may be configured to at least partially surround the filtration material. The filter element wrapper may be configured to fully surround the filtration material. The filter element wrapper may be wrapped around the filtration material.

[0082] The filter element may consist of the filter element wrapper and the filtration material. The filter element may consist of the filtration material wrapped by the filter element wrapper

[0083] The filter element wrapper may be configured to stabilise the filtration material. The filter element wrapper may be configured to protect the filtration material. The filter element wrapper may be configured to stabilize the body of discrete fragments of foam. The filter element wrapper may be configured to hold the discrete fragments of foam in the desired arrangement. The filter element wrapper may be configured to stabilize the arrangement the discrete fragments.

[0084] The filtration material may be arranged on a longitudinal axis of the filter element. The filter element wrapper may be coaxially arranged around the filtration material. The filter element wrapper may be permanently attached to the filtration material. The filter element wrapper may be glued to the filtration material by a starch glue.

[0085] The filter element wrapper may have a permeability of between 3500 Coresta Units and 12000 Coresta Units.

[0086] The filter element wrapper may have a thickness of between 0.2 micrometers and 0.4 micrometers.

[0087] The filter element wrapper may have a basis weight of between 10 g / m and 30 g / m, preferably of between 17 g / m and 21 g / m.

[0088] The filter element wrapper may be made from a paper material. The filter element wrapper may be biodegradable. The filter element wrapper may be recyclable.

[0089] The filter element may comprise a tipping paper. The tipping paper may be configured to at least partially circumscribe the filter element wrapper. The tipping paper may be configured to fully circumscribe the filter element wrapper.

[0090] The tipping paper may be configured to at least partially circumscribe the filtration material. The tipping paper may be configured to fully circumscribe the filtration material. The tipping paper may be configured to at least partially circumscribe the discrete fragments of foam. The tipping paper may be configured to fully circumscribe the discrete fragments of foam.

[0091] The tipping paper may be wrapped around the filtration material. The tipping paper may be wrapped around the discrete fragments of foam. The tipping paper and may be wrapped around the rod-shaped body of the discrete fragments of foam. The tipping paper may be coaxially arranged around the filter element wrapper.

[0092] The tipping paper may have a textured surface. The tipping paper may have a textured outer surface. The tipping paper may have an embossed surface. The tipping paper may have an embossed outer surface. The tipping paper may have a smooth surface. The tipping paper may have a smooth outer surface.

[0093] The tipping paper may have a permeability of between 380 Coresta Units and 550 Coresta Units.

[0094] The tipping paper may have a thickness of between 0.5 micrometers and 1.1 micrometers.

[0095] The tipping paper may have a basis weight of between 25 g / m and 60 g / m, preferably of between 30 g / m and 50 g / m.

[0096] The filter element may have a length of between 5 millimeters and 21 millimeters, preferably of between 7 millimeters and 11 millimeters.

[0097] The filter element may have an outer diameter of between 3 millimeters and 10 millimeters, preferably of between 4 millimeters and 9 millimeters. The active material may be activated charcoal. The granules may be made from activated charcoal.

[0098] The granules may consist of activated charcoal. The granules of activated charcoal may be porous. The active material may be activated carbon. The granules may be made from activated carbon. The activated charcoal may have an open-cell configuration.

[0099] A porosity of the filtration material may be of between 0.3 and 0.8, preferably of 0.4 and 0.7, and more preferably of between 0.5 and 0.6. The porosity may be the ratio of the pore volume of the filtration material and the overall volume of the filtration material.

[0100] A porosity of the foam may be larger than a porosity of the granules made from activated charcoal. The ratio of the porosity of the charcoal granules to the porosity of the foam may be of between 1 :1.10 and 1 :1.40, preferably of between 1 :1.15 and 1 :1.30.

[0101] The discrete fragment of foam may have a volume of between 0.1 mm3and 0.6 mm3, preferably of between 0.15 mm3and 0.45 mm3. Each of the discrete fragments of foam may have a volume of between 0.1 mm3and 0.6 mm3, preferably of between 0.15 mm3and 0.45 mm3.

[0102] The ratio of the volume of the discrete fragments of foam and the granules made from activated charcoal may be of between 1 :0.15 and 1 :0.50, preferably of between 1 :0.20 and 1 :0.35.

[0103] The charcoal granules may have a diameter of between 0.1 millimeters and 0.75 millimeters, preferably of about 0.15 millimeters and 0.55 millimeters.

[0104] The charcoal may be coconut activated charcoal. The charcoal may be coconut activated charcoal in fine granules.

[0105] The chemical functional surface areas of the charcoal may be of between 500 m2 / g and 3000 m2 / g. The BET surface area of the charcoal may be of between 1350 m2 / g and 2550 m2 / g. The micropore volume of the charcoal may be of between 0.25 cm3 / g and 0.85 cm3 / g. The average pore radius of the charcoal may be of between 2.5 Angstrom and 15.5 Angstrom. The total pore volume of the charcoal may be of between 0.55 cm3 / g and 1.75 cm3 / g.

[0106] The foam may comprise a plasticizer. The filtration material may comprise the plasticiser in an amount of between 3 weigth-% and 10 weigth-%, preferably of between 4 weigth-% and 8 weigth-%. The plasticizer may be triacetin.

[0107] The filtration material may be free of plasticizer. The porous fibrous material may be free of plasticizer.

[0108] The active material may be a flavoring material. The granules may consist of the flavoring material. The granules may comprise the flavoring material. The flavoring material may be applied to the granules. The granules may support the flavoring material. The flavoring material may be configured to flavor an aerosol to be inhaled by the consumer. The flavoring material may comprise be a liquid. The flavoring material may be a gel.

[0109] The flavoring material may comprise a flavor. The flavoring material may comprise menthol. The flavoring material may be configured to be volatized. The flavoring material may be configured to enrich the flavor of an aerosol travelling through the filter element.

[0110] The air flow or aerosol flow may be a deviated by the granules. The flow may be deviated around the granules. Volatized flavoring material may be released from the granules into the flow deviated around the granules. The flow deviated around the granules may be enriched with the flavoring material. Volatized flavoring material may be released from the granules into the turbulent flow at the granules.

[0111] The granules may be impregnated with the flavoring material. Impregnation may effectively immobilize the flavoring material to the granules. Impregnation may effectively immobilize the flavoring material to the pores of the granules. The granules may be coated with the flavoring material. The flavoring material may be adsorbed to the granules. The flavoring material may be adsorbed to a surface of the granules. The flavoring material may be adsorbed to an inner surface of the granules. The flavoring material may penetrate at least a portion of the granule. The flavoring material may penetrate the granule. The flavoring material may be arranged on a surface of the granule. The flavoring material may at least partially be arranged inside the granule. The flavoring material may be immobilized in the granules.

[0112] The granules may be made from one or more of igneous rock, sedimentary rock and a ceramic. One or both of the igneous rock and the sedimentary rock may have a low density.

[0113] The material from which the granules are formed may be of higher density than the foam from which the discrete fragments of foam are formed.

[0114] The granules may comprise a porous material.

[0115] The porous material may comprise pores. The granules may be made from a porous material. The flavoring material may be applied to the porous material. The flavoring material may be immobilized in the porous material. The flavoring material may be immobilized in the pores of the porous material. The granules may be made from a partially porous material. The granules may be made from a non-porous material. The granules may be made from a gel comprising the flavoring material. The granules may be made from non-porous gel comprising the flavoring material.

[0116] The granules may have a diameter of between 0.1 millimeters and 2.5 millimeters, preferably of between 0.5 millimeters and 1.5 millimeters. The granules having a diameter of between 0.1 millimeters and 2.5 millimeters, preferably of between 0.5 millimeters and 1.5 millimeters may be impregnated with the flavoring material.

[0117] The porous material may have an open-cell configuration.

[0118] The open-cell porous material may be configured to provide an air flow path through at least a portion of the porous material. The flavoring material may be immobilized in the pores of the porous material having the open-cell configuration.

[0119] The granules may be configured to trap flavoring material within the granule. The granules may be configured to trap liquid flavoring material within the granule. The pore size of the porous material may be configured to trap liquid flavoring material within the granule. Volatized flavoring material may be released from the granule. The flavoring material may be applied to walls defining the pores of the porous material. The flavoring material may be applied on an inside surface of the granule. The granules may be configured to releasably enclose the flavoring material. The flavoring material may be microencapsulated by the granule. The flavoring material may be immobilized within the granule.

[0120] The porous material may have pore size that is smaller than a drop size of the liquid flavoring material. The porous material may have a pore size of between 1.3 millimeters and 1 micrometer, preferably of between 1.1 millimeters and 5 micrometers. The porous material may have a maximum pore size of about 1.3 millimeters, preferably of about 1.1 millimeters. The porous material may have a minimum pore size of between 1 micrometer and 100 micrometers, preferably of between 5 micrometers and 30 micrometers. The porosity of the porous material may be of between 0.3 and 0.7

[0121] Granules having flavor material immobilized by microencapsulation may be stable at a broad range of environmental temperatures and humidity. The risk of contamination of the surrounding fragments of foam by flavoring material may be reduced or avoided in a broad range of environmental conditions. Deterioration of the filter element due to undesired release of flavoring material during storage may be reduced. Deterioration of the filter element due to undesired release of flavoring material by external forces acting on the filter element may be reduced.

[0122] The porous material may be selected from one of a ceramic, sedimentary rock and expanded clay.

[0123] The ceramic, sedimentary rock and the expanded clay may have an open-cell configuration. Granules made from the ceramic may offer improved chemical stability. Granules made from the ceramic may offer improved thermal stability. One or both of the pore size and the porosity for granules made from the ceramic may be easily adjusted. The expanded clay may comprise pores arranged in a honeycomb structure. The granules made from the expanded clay may have a substantially spherical shape. The expanded clay may be manufactured by heating natural clay in a rotary kiln at temperatures of above approximately 1200 degrees Celsius.

[0124] The sedimentary rock may be selected from one of limestone and sandstone.

[0125] The granules of expanded clay may have a diameter of between 0.1 millimeters and 2.5 millimeters preferably of between 0.15 millimeters and 1.5 millimeters.

[0126] A porosity of the sedimentary rock may be of between 0.3 and 0.5.

[0127] A porosity of the ceramic may be of between 0.3 and 0.8, preferably of 0.4 and 0.7.

[0128] The amount of flavoring material in the granule made from the ceramic may be controlled by adjusting the porosity of the ceramic.

[0129] The porous material may be impregnated with the flavoring material. Impregnation may effectively immobilize the flavoring material to the granules.

[0130] The porous material may have a closed-cell configuration.

[0131] The surface area to volume ratio of the granules may be maximised. The surface area to volume ratio of the granules coated with the flavoring material may be maximised in order to maximise the surface area of flavoring material. The granules may have a substantially spherical shape. For a given volume of granules per volume of the body of the discrete fragments of foam, the number of granules may be maximized.

[0132] Porous material having a closed-cell configuration may be advantageously used with strongly flavored flavoring material. Porous material havinga closed-cell configuration may be advantageously used with menthol.

[0133] The surface of the granules may be provided with pores. The pores may be coated with flavoring material. The surface of the granules may be provided with indentations. The indentations may be coated with flavoring materials.

[0134] The porous material may be igneous rock, preferably wherein igneous rock is selected from one of Pumice, Scoria and vesicular Basalt.

[0135] The igneous rock may have a closed-cell configuration. Pumice may have a porosity of 0.85.

[0136] Granules of igneous rock may have pores provided on the outer surface of granule, such that the adsorption process of the flavoring material to the granule will make flavoring material also coat the inside surfaces of the pores. Such arrangement may protect the fluid from interactions with outside components, including flavoring material which will not be able to enter into the vesicles due to the air trapped into the pores. Such configuration may be used when the flavoring material should be used in relatively small quantities, such as in the case of strong flavoring agents such as menthol, as the adsorption process feed the granules with less fluid than the capillary action.

[0137] The porous material may be coated with the flavoring material.

[0138] The filter element may comprise a first filtration material as described herein. The filter element may comprise a second filtration material as described herein. The first filtration material may be arranged upstream of the second filtration material.

[0139] The first filtration material may comprise granules comprising activated charcoal. The first material may comprise granules consisting of activated charcoal. The second filtration material may comprise granules comprising the flavoring material. The filter element may comprise a first filtration material comprising granules made from activated charcoal and a second filtration material comprising granules with the flavoring material. The filter element wrapper may be configured to at least partially circumscribe the first filtration material and the second filtration material. The filter element wrapper may be configured to fully circumscribe the first filtration material and the second filtration material. The filter element wrapper may be configured to fix the relative positions of the first filtration material and the second filtration material.

[0140] Alternatively, the first filtration material may be wrapped with a first filter element wrapper. The second filtration material may be wrapped with a second filter element wrapper.

[0141] The first filtration material and the second filtration material may be wrapped with the tipping paper. The first filtration material and the second filtration material may be at least partially circumscribed by the tipping paper. The first filtration material and the second filtration material may be fully circumscribed by the tipping paper. The filter element wrapper may be circumscribed by the tipping paper. The first filter element wrapper and the second filter element wrapper may be circumscribed by the tipping paper.

[0142] The first filtration material may provide efficient filtering of the aerosol due to the presence of the charcoal granules. The second filtration material may provide flavoring to the aerosol due to the presence of granules comprising flavoring material. By providing the first filtration material upstream of the second filtration material, flavoring efficiency may be improved. By providing the first filtration material upstream of the second filtration material, removal by the first filtration material of flavoring material volatized from the second filtration material may be avoided. The resistance-to-draw of the first filtration material may be the same as the resistance-to-draw of the second filtration material.

[0143] A length of the filter element may be of between 9 millimeters and 30 millimeters, preferably of between 10 millimeters and 20 millimeters. A length of the filter element having the first and second filtration material may be of between 9 millimeters and 30 millimeters, preferably of between 10 millimeters and 20 millimeters.

[0144] A length of the first filtration material may be of between 5 millimeters and 17 millimeters, preferably of between 6 millimeters and 10 millimeters.

[0145] A length of the second filtration material may be of between 4 millimeters and 12 millimeters, preferably of between 5 millimeters and 9 millimeters. A length of the body of discrete fragments of foam of the first filtration material may be of between 5 millimeters and 17 millimeters, preferably of between 6 millimeters and 10 millimeters.

[0146] A length of the second filtration material may be of between 4 millimeters and 12 millimeters, preferably of between 5 millimeters and 9 millimeters. A length of the body of discrete fragments of foam of the second filtration material may be of between 4 millimeters and 12 millimeters, preferably of between 5 millimeters and 9 millimeters.

[0147] The filter element of the invention may be manufactured using standard equipment.

[0148] In a preferred embodiment of the invention, the filtration material may comprise granules made from activated charcoal. The granules made from activated charcoal may be sandwiched between the fragments of foam. The granules made from activated charcoal may be homogeneously distributed between the discrete fragments of foam. The foam may be a foam of regenerated cellulose. The foam may be free of cellulose acetate. The filtration material may be a rod. The filtration material may be fully circumscribed by the filter element wrapper. The filter element wrapper may be fully circumscribed by the tipping paper. The filter element may provide efficient and adjustable filtration due to the combination of aerosol flow through and around the fragments of foam and the charcoal granules. The fragments of foam and charcoal granules may efficiently remove undesired compounds from the aerosol flow. Due to the turbulent flow induced by and located at the charcoal granules, the filtering efficiency provided by the charcoal granules may be improved.

[0149] In another preferred embodiment of the invention, the filter element may comprise granules provided with the flavoring material. The granules provided with the flavoring material may be sandwiched between the fragments of foam. The granules provided with the flavoring material may be homogeneously distributed between the discrete fragments of foam. The foam may be a foam of regenerated cellulose. The foam may be free of cellulose acetate. The filtration material may be a rod. The filtration material may be fully circumscribed by the filter element wrapper. The filter element wrapper may be fully circumscribed by the tipping paper. The granules may have an open-cell configuration and may be impregnated with the flavoring material. For example, the granules may be made from one of a ceramic, sedimentary rock and expanded clay and such granules may be impregnated with the flavoring material. The flavoring material may at least partially be arranged in the pores of the granule. Alternatively, the granules may have a closed-cell configuration and may be coated with the flavoring material. For example, the granules may be made of igneous rock, preferably selected from one of Pumice, Scoria and vesicular Basalt, and may be coated with the flavoring material. Alternatively, the granules may be made of a gel holding the flavoring material. The filter element may provide efficient filtration together with flavoring the aerosol with volatized flavoring material. Due to the turbulent flow induced by and located at the granules provided with the flavoring material, the efficiency of flavoring of the aerosol may be improved.

[0150] In a further preferred embodiment of the invention, the filter element may comprise the first filtration material comprising granules made from activated charcoal and the second filtration material comprising granules provided with the flavoring material. The foam of the first filtration material and of the second filtration material may be a foam of regenerated cellulose. The foam of the first filtration material and the second filtration material may be free of cellulose acetate. The granules made from activated charcoal may be sandwiched between the discrete fragments of foam of the first filtration material. The granules made from activated charcoal may be homogeneously distributed between the discrete fragments of foam of the first filtration material. The granules provided with the flavoring material may be sandwiched between the discrete fragments of foam of the second filtration material. The granules having the flavoring material may be homogeneously distributed between the discrete fragments of foam of the second filtration material. The first filtration material may be a rod. The second filtration material may be a rod. The first filtration material may be wrapped by a first filter element wrapper. The second filtration material may be wrapped by a second filter element wrapper. The first filtration element may be arranged upstream of the second filtration material. The first filtration material wrapped by the first filter element wrapper and the second filtration material wrapped by the second filter element wrapper may be circumscribed by the tipping paper to form the filter element. The filter element may provide efficient filtering together with additionally flavoring the aerosol. By providing the first filtration material upstream of the second filtration material, undesired removal of volatized flavoring material may be reduced or avoided.

[0151] The invention further relates to an aerosol-generating article comprising the filter element as described herein.

[0152] The aerosol-generating article may comprise an aerosol-forming substrate.

[0153] The invention further relates to an aerosol-generating system comprising the aerosolgenerating article as described herein and an aerosol-generating device.

[0154] The invention further relates to a method for manufacturing a filtration material for a filter element as described herein which may comprise the following steps:

[0155] (a) providing a plurality of discrete fragments of foam of cellulosic material (b) providing a plurality of granules comprising an active material,

[0156] (c) distributing the granules between the discrete fragments of foam.

[0157] The invention further relates to a method for manufacturing a filtration material for a filter element as described herein comprising the following steps:

[0158] (a) providing a plurality of discrete fragments of foam of cellulosic material

[0159] (b) providing a plurality of granules comprising an active material,

[0160] (c) distributing the granules between the discrete fragments of foam.

[0161] As used herein, the terms ‘proximal’, ‘distal’, ‘downstream’ and ‘upstream’ may be used to describe the relative positions of components, or portions of components, of the aerosolgenerating device in relation to the direction in which a user draws on the aerosol-generating device during use thereof.

[0162] As used herein, the terms ‘proximal’, ‘distal’, ‘downstream’ and ‘upstream’ may be used to describe the relative positions of components, or portions of components, of the aerosolgenerating article in relation to the direction in which a user draws on the aerosol-generating article during use thereof.

[0163] The aerosol-generating device may comprise a mouth end through which in use an aerosol exits the aerosol-generating device and is delivered to a user. The mouth end may also be referred to as the proximal end. In use, a user may draw on the proximal or mouth end of the aerosol-generating device in order to inhale an aerosol generated by the aerosolgenerating device. The mouth end may comprise a mouthpiece. Alternatively, a user may directly draw on an aerosol-generating article inserted into an opening at the proximal end of the aerosol-generating device. The opening at the proximal end may be an opening of the cavity. The cavity may be configured to receive the aerosol-generating article. The aerosolgenerating device may comprise a distal end opposed to the proximal or mouth end. The proximal or mouth end of the aerosol-generating device may also be referred to as the downstream end and the distal end of the aerosol-generating device may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal, downstream or mouth end and the distal or upstream end of the aerosol-generating device.

[0164] The aerosol-generating article may comprise a mouth end through which in use an aerosol exits the aerosol-generating article and is delivered to a user. The mouth end may also be referred to as the proximal end. The filter element as described herein may be arranged at the mouth end of the article. The aerosol-generating article may comprise a distal end opposed to the proximal or mouth end. The proximal or mouth end of the aerosol-generating article may also be referred to as the downstream end and the distal end of the aerosol-generating article may also be referred to as the upstream end. The filter element is described herein may be arranged proximal to the aerosol-forming substrate.

[0165] A longitudinal axis of a component may extend between a proximal end of the component and a distal end of the component. A longitudinal axis of the filter element may extend between a proximal end of the filter element and a distal end of the filter element. A longitudinal axis of the aerosol-generating article may extend between a proximal end of the article and a distal end of the article. A longitudinal axis of the aerosol-generating device may extend between the proximal end of the device and a distal end of the device.

[0166] As used herein, an ‘aerosol-generating device’ may relate to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-generating article may comprise a mouthpiece. The aerosol-forming substrate may be part of the aerosol-generating article. An aerosol-generating device may be a smoking device that interacts with an aerosolforming substrate of the aerosol-generating article to generate an aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. An aerosol-generating device may be a holder. The device may be an electrically heated smoking device. The aerosol-generating device may comprise a housing, electric circuitry, a power supply, a heating chamber and a heating element.

[0167] The aerosol-generating device may comprise electric circuitry. The electric circuitry may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of a controller. The electric circuitry may comprise further electronic components. The electric circuitry may be configured to regulate a supply of power to the heating element. Power may be supplied to the heating element continuously following activation of the aerosol-generating device or may be supplied intermittently, such as on a puff- by-puff basis. The power may be supplied to the heating element in the form of pulses of electrical current. The electric circuitry may be configured to monitor the electrical resistance of the heating element, and preferably to control the supply of power to the heating element dependent on the electrical resistance of the heating element.

[0168] The aerosol-generating device may comprise a power supply, typically a battery, within a main body of the aerosol-generating device. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, 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, Lithium Titanate or a Lithium-Polymer battery. As an alternative, 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 enables to store enough energy for one or more usage experiences; for example, the power supply may have sufficient capacity to continuously generate aerosol for a period of around six minutes or for a period of a multiple of six minutes. In another example, the power supply may have sufficient capacity to provide a predetermined number of puffs or discrete activations of the heating element.

[0169] The cavity of the aerosol-generating device may have an open end into which the aerosol-generating article is inserted. The open end may be a proximal end. The cavity may have a closed end opposite the open end. The closed end may be the base of the cavity. The closed end may be closed except for the provision of air apertures arranged in the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be arranged upstream of the cavity. The open end may be arranged downstream of the cavity. The cavity may have an elongate extension. The cavity may have a longitudinal central axis. A longitudinal direction may be the direction extending between the open and closed ends along the longitudinal central axis. The longitudinal central axis of the cavity may be parallel to the longitudinal axis of the aerosol-generating device.

[0170] The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received in the cavity. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular crosssection. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article.

[0171] An airflow channel may run through the cavity. Ambient air may be drawn into the aerosol-generating device, into the cavity and towards the user through the airflow channel. Downstream of the cavity, a mouthpiece may be arranged or a user may directly draw on the aerosol-generating article. The airflow channel may extend through the mouthpiece.

[0172] In any of the aspects of the disclosure, the heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required. As described, in any of the aspects of the disclosure, the heating element may be part of an aerosol-generating device. The aerosol-generating device may comprise an internal heating element or an external heating element, or both internal and external heating elements, where "internal" and "external" refer to the aerosol-forming substrate. An internal heating element may take any suitable form. For example, an internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different electro-conductive portions, or an electrically resistive metallic tube. Alternatively, the internal heating element may be one or more heating needles or rods that run through the center of the aerosol-forming substrate. Other alternatives include a heating wire or filament, for example a Ni-Cr (Nickel-Chromium), platinum, tungsten or alloy wire or a heating plate. Optionally, the internal heating element may be deposited in or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as ceramic material, and then sandwiched in another insulating material, such as a glass. Heaters formed in this manner may be used to both heat and monitor the temperature of the heating elements during operation.

[0173] An external heating element may take any suitable form. For example, an external heating element may take the form of one or more flexible heating foils on a dielectric substrate, such as polyimide. The flexible heating foils can be shaped to conform to the perimeter of the substrate receiving cavity. Alternatively, an external heating element may take the form of a metallic grid or grids, a flexible printed circuit board, a molded interconnect device (MID), ceramic heater, flexible carbon fiber heater or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate. An external heating element may also be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating materials. An external heating element formed in this manner may be used to both heat and monitor the temperature of the external heating element during operation.

[0174] As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. In general, a susceptor is a material that is capable of generating heat, when penetrated by an alternating magnetic field. When located in an alternating magnetic field. If the susceptor is conductive, then typically eddy currents are induced by the alternating magnetic field. If the susceptor is magnetic, then typically another effect that contributes to the heating is commonly referred to hysteresis losses. Hysteresis losses occur mainly due to the movement of the magnetic domain blocks within the susceptor, because the magnetic orientation of these will align with the magnetic induction field, which alternates. Another effect contributing to the hysteresis loss is when the magnetic domains will grow or shrink within the susceptor. Commonly all these changes in the susceptor that happen on a nano-scale or below are referred to as “hysteresis losses”, because they produce heat in the susceptor. Hence, if the susceptor is both magnetic and electrically conductive, both hysteresis losses and the generation of eddy currents will contribute to the heating of the susceptor. If the susceptor is magnetic, but not conductive, then hysteresis losses will be the only means by which the susceptor will heat, when penetrated by an alternating magnetic field. According to the invention, the susceptor may be electrically conductive or magnetic or both electrically conductive and magnetic. An alternating magnetic field generated by one or several induction coils heat the susceptor, which then transfers the heat to the aerosol-forming substrate, such that an aerosol is formed. The heat transfer may be mainly by conduction of heat. Such a transfer of heat is best, if the susceptor is in close thermal contact with the aerosol-forming substrate.

[0175] As used herein, the term ‘aerosol-generating article’ may refer to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. For example, an aerosol-generating article may be a smoking article that generates an aerosol that is directly inhalable into a user’s lungs through the user's mouth. An aerosolgenerating article may be disposable.

[0176] The aerosol-generating article may be a combustible cigarette. The aerosol-generating article may comprise a rod of tobacco and the filter element described herein. The tobacco may be burnt. A user may lit the cigarette to burn the tobacco.

[0177] As used herein, the term ‘aerosol-forming substrate’ may relate to a substrate capable of releasing one or more volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. An aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article. In a combustible cigarette, the substrate may be burnt. The substrate may comprise tobacco.

[0178] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosolforming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerine and propylene glycol. The aerosol-generating substrate may comprise homogenised tobacco material, an aerosol-former and water. Providing homogenised tobacco material may improve aerosol generation, the nicotine content and the flavour profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenised tobacco involves grinding tobacco leaf, which more effectively enables the release of nicotine and flavours upon heating.

[0179] 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.

[0180] Example 1 : A filter element for an aerosol-generating article, wherein the filter element comprises a filtration material, wherein the filtration material comprises a plurality of granules comprising an active material, wherein the filtration material comprises a plurality of discrete fragments of foam of cellulosic material, and wherein the granules are distributed between the discrete fragments of foam.

[0181] Example 2: The filter element according to example 1 , wherein the filtration material consists of the plurality of granules and the plurality of discrete fragments of foam.

[0182] Example 3: The filter element according to example 1 or example 2, wherein the filtration material is free of cellulose acetate.

[0183] Example 4: The filter element according to any of the preceding examples, wherein the cellulosic material is regenerated cellulose.

[0184] Example 5: The filter element according to any of the preceding examples, wherein the foam is based on one or more of a wood pulp, a bamboo pulp, pulps obtained from tobacco stems, and hybrid forms of nanocellulose and kaolin-microfibrillated cellulose composites.

[0185] Example 6: The filter element according to any of the preceding examples, wherein the granules are homogeneously distributed between the discrete fragments of foam.

[0186] Example 7: The filter element according to any of the preceding examples, wherein the filter element is cylindrically shaped, preferably wherein the filter element is a rod.

[0187] Example 8: The filter element according to any of the preceding examples, wherein the filter element comprises a filter element wrapper configured to at least partially, preferably fully circumscribe the filtration material.

[0188] Example 9: The filter element according to example 8, wherein the filter element wrapper is made from a paper material.

[0189] Example 10: The filter element according to example 8 or example 9, wherein the filter element comprises a tipping paper, wherein the tipping paper is configured to at least partially, preferably fully circumscribe the filter element wrapper. Example 11 : The filter element according to any of the preceding examples, wherein the filter element has a length of between 5 millimeters and 21 millimeters, preferably of between 7 millimeters and 11 millimeters.

[0190] Example 12: The filter element according to any of the preceding examples, wherein the filter element has an outer diameter of between 3 millimeters and 10 millimeters, preferably of between 4 millimeters and 9 millimeters.

[0191] Example 13: The filter element according to any of the preceding examples, wherein the active material is activated charcoal, and wherein the granules are made from activated charcoal.

[0192] Example 14: The filter element according to example 13, wherein a porosity of the filtration material is of between 0.3 and 0.8, preferably of 0.4 and 0.7, and more preferably of between 0.5 and 0.6, wherein the porosity is the ratio of the pore volume of the filtration material and the overall volume of the filtration material.

[0193] Example 15: The filter element according to example 13 or example 14, wherein a porosity of the foam is larger than a porosity of the granules made from activated charcoal, preferably wherein the ratio of the porosity of the charcoal granules to the porosity of the foam is of between 1 :1.10 and 1 : 1.40, preferably of between 1 :1.15 and 1 : 1.30.

[0194] Example 16: The filter element according to any of examples 13 to 15, wherein the discrete fragments of foam have volume of between 0.1 mm3and 0.6 mm3, preferably of between 0.15 mm3and 0.45 mm3.

[0195] Example 17: The filter element according to any of examples 13 to 16, wherein a ratio of the volume of the discrete fragments of foam and the granules made from activated charcoal is of between 1 :0.15 and 1 :0.50, preferably of between 1 :0.20 and 1 :0.35.

[0196] Example 18: The filter element according to any of examples 13 to 17, wherein the charcoal granules have a diameter of between 0.1 millimeters and 0.75 millimeters, preferably of about 0.15 millimeters and 0.55 millimeters.

[0197] Example 19: The filter element according to any of examples 13 to 18, wherein the foam comprises a plasticiser, preferably triacetin, preferably wherein the filtration comprises the plasticiser in an amount of between 3 weigth-% and 10 weigth-%, preferably of between 4 weigth-% and 8 weigth-%.

[0198] Example 20: The filter element according to any of examples 1 to 12, wherein the active material is a flavoring material, optionally wherein granules consist of the flavoring material.

[0199] Example 21 : The filter element according to example 20, wherein the granules comprise a porous material. Example 22: The filter element according to example 20 and example 21 , wherein the granules have a diameter of between 0.1 millimeters and 2.5 millimeters, preferably of between 0.5 millimeters and 1.5 millimeters.

[0200] Example 23: The filter element according to any of examples 20 to 22, wherein the porous material has an open-cell configuration.

[0201] Example 24: The filter element according to example 23, wherein the porous material has a pore size of between 1.3 millimeters and 1 micrometer, preferably of between 1.1 millimeters and 5 micrometers.

[0202] Example 25: The filter element according to example 23 or example 24, wherein the porous material is selected from one of a ceramic, sedimentary rock and expanded clay.

[0203] Example 26: The filter element according to example 25, wherein the sedimentary rock is selected from one of limestone and sandstone.

[0204] Example 27: The filter element according to example 25, wherein the granules of expanded clay have a diameter of between 0.1 millimeters and 2.5 millimeters preferably of between 0.15 millimeters and 1.5 millimeters.

[0205] Example 28: The filter element according to example 25 or example 26, wherein a porosity of the sedimentary rock is of between 0.3 and 0.5.

[0206] Example 29: The filter element according to example 25, wherein a porosity of the ceramic is of between 0.3 and 0.8, preferably of 0.4 and 0.7.

[0207] Example 30: The filter element according to any of examples 23 to 29, wherein the porous material is impregnated with the flavoring material.

[0208] Example 31 : The filter element according to example 21 or example 22, wherein the porous material has a closed-cell configuration.

[0209] Example 32: The filter element according to example 31 , wherein the porous material is igneous rock, preferably wherein igneous rock is selected from one of Pumice, Scoria and vesicular Basalt.

[0210] Example 33: The filter element according to example 31 or example 32, wherein the porous material is coated with the flavoring material.

[0211] Example 34: The filter element according to any of the preceding examples, wherein the filter element comprises a first filtration material according to any of examples 13 to 19 and a second filtration material according to any of examples 20 to 33, wherein the first filtration material is arranged upstream of the second filtration material.

[0212] Example 35: The filter element according to example 34, wherein a length of the filter element is of between 9 millimeters and 30 millimeters, preferably of between 10 millimeters and 20 millimeters. Example 36: The filter element according to example 34 or example 35, wherein a length of the first filtration material is of between 5 millimeters and 17 millimeters, preferably of between 6 millimeters and 10 millimeters.

[0213] Example 37: The filter element according to any of examples 34 to 36, wherein a length of the second filtration material is of between 4 millimeters and 12 millimeters, preferably of between 5 millimeters and 9 millimeters.

[0214] Example 38: An aerosol-generating article comprising the filter element according to any of examples 1 to 37.

[0215] Example 39: The aerosol-generating article according to example 38 comprising an aerosol-forming substrate.

[0216] Example 40: An aerosol-generating system comprising the aerosol-generating article according to any of examples 38 and 39 and an aerosol-generating device.

[0217] Example 41 : A method for manufacturing a filtration material for a filter element according to any of examples 1 to 37 comprising the following steps:

[0218] (a) providing a plurality of discrete fragments of foam of cellulosic material

[0219] (b) providing a plurality of granules comprising an active material,

[0220] (c) distributing the granules between the discrete fragments of foam.

[0221] Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

[0222] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0223] Fig. 1 shows a filter element comprising granules made from activated charcoal according to the invention;

[0224] Fig. 2 shows the filter element of Fig. 1 with partially removed filter element wrapper and tipping paper;

[0225] Fig. 3 shows the filter element comprising the filter element wrapper and a filtration material comprising the charcoal granules;

[0226] Fig. 4 shows the filter element of Fig. 3 and the tipping paper;

[0227] Fig. 5 shows the filter element comprising granules provided with flavoring material;

[0228] Fig. 6 shows the filter element of Fig. 5 with partially removed filter element wrapper and tipping paper;

[0229] Fig. 7 shows the filter element comprising flavoring material granules and the filter element wrapper;

[0230] Fig. 8 shows the filter element of Fig. 7 and the tipping paper; Fig. 9 shows the filter element comprising a first filtration material and a second filtration material.

[0231] Fig. 1 shows a filter element 10 comprising a filtration material 12 comprising a plurality of granules 14. Fig. 1A shows a three-dimensional view of the filter element 10. Fig. I B shows a longitudinal cross-section of the filter element 10. The granules 14 are made from activated charcoal. The filtration material comprises a plurality of discrete fragments 16 of foam. The foam is a foam of regenerated cellulose. The discrete fragments 16 of foam are cylindrically arranged. The charcoal granules 14 are homogeneously distributed between discrete fragments 16 of foam. The charcoal granules 14 are sandwiched between discrete fragments 16 of foam. The charcoal granules 14 are arranged in spaces 17 formed between the discrete fragments 16 of foam. The discrete fragments 16 of foam form a matrix for the charcoal granules 14. The discrete fragments 16 of foam may abut each other. The discrete fragments 16 of foam is circumscribed by a filter element wrapper 18. The filter element wrapper 18 is circumscribed by a tipping paper 20. Fig. 1 A shows a longitudinal axis 22 of the filter element. Fig. 1 B indicates a length 24 of the filter element and a width 26 of the filter element. The filtration material 12 extends along the length 24 of the filter element. The filter element has a cylindrical rod shape.

[0232] In use, filter element may be part of an aerosol-generating article, the user may pull air or aerosol through the filter element 10. The flow may be directed by the fragments of foam, the charcoal granules and the spaces between the fragments of foam. Turbulent flow induced by and located at the charcoal granules 14 may lead to a prolonged exposure of the flow to the activate charcoal granules 14. The activate charcoal granules 14 may more efficiently remove undesired components of the flow. The components removed by the activated charcoal may be complementary to components removed from the flow by the fragments 16 of foam.

[0233] Fig. 2 shows the filter element 10 of Fig. 1 with a partially removed filter element wrapper 18 and tipping paper 20. The filter element wrapper 18 and the tipping paper 20 are shown partially removed to illustrate the structure of the filter element 10 to the reader more clearly. The remarks relating to Fig. 1 correspondingly apply to Fig. 2.

[0234] Fig. 3 shows the filter element comprising the filter element wrapper 18 and a filtration material 12 comprising the charcoal granules. Fig. 3A shows the filter element wrapper 18 partially removed from the filtration material 12 to illustrate the structure of the filter element 10 to the reader more clearly. In Fig. 3B, the filter element wrapper 18 fully circumscribes the filtration material 12. Fig. 4 shows the filter element 10 of Fig. 3 and the tipping paper 20. Fig. 4A shows the tipping paper 20 partially removed from the filter element wrapper 18 to illustrate the structure of the filter element 10 to the reader more clearly. In Fig. 3A, the tipping paper 20 fully circumscribing the filter element wrapper 18.

[0235] Fig. 5 shows the filter element comprising a filtration material 12 having granules 14 provided with flavoring material. The remarks relating to Fig. 1 correspondingly apply to the filter element 10 of Fig. 5. However, the filter element of Fig. 5 comprises granules provided with a flavoring material instead of charcoal granules. The granules 14 may be formed from a porous material having an open-cell configuration or a closed-cell configuration. Granules 14 having an open-cell configuration may be impregnated with the flavoring material. Granules 14 having the closed-cell configuration may be coated with the flavoring material. The flavoring material may be immobilized to the granule.

[0236] In use, the filter element 10 may be incorporated into an aerosol-generating article. The user may pull air or aerosol through the filter element 10. The flavoring material may volatize to enrich the flavor of the flow travelling through the filter element 10.

[0237] Fig. 6 shows the filter element of Fig. 5 with partially removed filter element wrapper 18 and tipping paper 20. The filter element wrapper 18 and the tipping paper 20 are shown partially removed to illustrate the structure of the filter element 10 to the reader more clearly. The remarks relating to Fig. 5 correspondingly apply to Fig. 6.

[0238] Fig. 7 shows the filter element 10 comprising granules 14 provided with flavoring material and the filter element wrapper 18. Fig. 7A shows the filter element wrapper 18 partially removed from the filtration material 12 to illustrate the structure of the filter element 10 to the reader more clearly. In Fig. 7B, the filter element wrapper 18 fully circumscribes the filtration material.

[0239] Fig. 8 shows the filter element 10 of Fig. 7 and the tipping paper 20. Fig. 8A shows the tipping paper 20 partially removed from the filter element wrapper 18 to illustrate the structure of the filter element 10 to the reader more clearly. In Fig. 8A, the tipping paper 20 fully circumscribes the filter element wrapper 10.

[0240] Fig. 9 shows the filter element comprising a first filtration material 12A and a second filtration material 12B. The first filtration material is filtration material 14A comprising charcoal granules as described in Figs. 1 to 4. The second filtration material is the filtration material comprising flavoring material granules 14B as described in Figs. 5 to 8. The first filtration material 12A and the second filtration material 12B comprise discrete fragments 16 of a regenerated cellulose foam. The first filtration material 12A is circumscribed by a first filter element wrapper 18A. The second filtration material 12B is circumscribed by a second filter element wrapper 18B. The first filter element wrapper 18A and the second filter element wrapper 18B are wrapped by a single tipping paper 20.

[0241] The first filtration material 12A is arranged upstream of the second filtration material 12B. An upstream air flow or aerosol flow 28 may enter the upstream end of first filtration material 12A. The flow may initially travel through the first filtration material 12A. The first filtration material may remove undesired compounds from the flow. The flow may subsequently enter the upstream end of the second filtration material 12B. Flavoring material may be released from the granules 14B provided with flavoring material to enrich the flavor of flow through the second filtration material 12B. The flow may leave the filter element 10 in a downstream air flow or aerosol flow 30. By providing the first filtration material 12A upstream of the second filtration material 12B, undesired removal of flavor released from the granules 14B provided with flavorin material may be reduced or avoided.

Claims

CLAIMS1. A filter element for an aerosol-generating article, wherein the filter element comprises a filtration material, wherein the filtration material comprises a plurality of granules comprising an active material, wherein the filtration material comprises a plurality of discrete fragments of foam of cellulosic material, and wherein the granules are distributed between the discrete fragments of foam.

2. The filter element according to claim 1 , wherein the filtration material is free of cellulose acetate.

3. The filter element according to claim 1 or claim 2, wherein the cellulosic material is regenerated cellulose.

4. The filter element according to any of the preceding claims, wherein the granules are homogeneously distributed between the discrete fragments of foam.

5. The filter element according to any of the preceding claims, wherein the filter element comprises a filter element wrapper configured to at least partially, preferably fully circumscribe the filtration material.

6. The filter element according to any of the preceding claims, wherein the discrete fragment of foam has volume of between 0.1 mm3and 0.6 mm3, preferably of between 0.15 mm3and 0.45 mm3.

7. The filter element according to any of the preceding claims, wherein the active material is activated charcoal, and wherein the granules are made from activated charcoal.

8. The filter element according to claim 7, wherein a ratio of the volume of the discrete fragments of foam and the granules made from activated charcoal is of between 1 :0.15 and 1 :0.50, preferably of between 1 :0.20 and 1 :0.35.

9. The filter element according to any of claims 1 to 6, wherein the active material is a flavoring material, optionally wherein the granules consist of the flavoring material.

10. The filter element according to claim 9, wherein the granules comprise a porous material, wherein the porous material has an open-cell configuration, wherein the porousmaterial is impregnated with the flavoring material, preferably wherein the porous material is selected from one of a ceramic, sedimentary rock and expanded clay.11 . The filter element according to claim 9, wherein the granules comprise a porous material, wherein the porous material has a closed-cell configuration, wherein the porous material is coated with the flavoring material, preferably wherein the porous material is igneous rock.

12. The filter element according to any of the preceding claims, wherein the filter element comprises a first filtration material according to claim 7 or claim 8 and a second filtration material according to any of claims 9 to 11 , wherein the first filtration material is arranged upstream of the second filtration material.

13. An aerosol-generating article comprising the filter element according to any of claims 1 to 12.

14. An aerosol-generating system comprising the aerosol-generating article according to claim 13 and an aerosol-generating device.

15. A method for manufacturing a filtration material for a filter element according to any of claims 1 to 12 comprising the following steps:(a) providing a plurality of discrete fragments of foam of cellulosic material(b) providing a plurality of granules comprising an active material,(c) distributing the granules between the discrete fragments of foam.

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