JP2024125411A - Smoking substitute consumables - Google Patents

Abstract

The present invention provides an aerosol-forming article (e.g., a heat-not-burn (HNB) consumable) that includes an aerosol-forming substrate and a plurality of filter elements, at least two of which have different hardnesses from one another.

Description

The present disclosure relates to consumables for use in smoking substitution systems, and more particularly, but not exclusively, to heat-not-burn (HNB) consumables.

Tobacco smoking is generally regarded as exposing smokers to potentially harmful substances. It is generally believed that significant amounts of potentially harmful substances are produced through the burning of tobacco and/or the heat caused by tobacco combustion, as well as through the burnt tobacco components in the tobacco smoke itself.

A conventional combustible smoking article, such as a cigarette, typically includes a cylindrical tobacco rod comprising strips of tobacco surrounded by a wrapper, and typically also includes a cylindrical filter axially aligned in abutting relationship with the rolled tobacco rod. The filter typically includes a filtration material circumscribed by a plug wrap. The rolled tobacco rod and filter are held together by a rolled strip of tipping paper that circumscribes the entire length of the filter and adjacent portions of the rolled tobacco rod. This type of conventional cigarette is used by lighting the end opposite the filter to burn the tobacco rod. The smoker receives mainstream smoke from his or her mouth by drawing on the mouth or filter end of the cigarette.

The combustion of organic materials such as tobacco is known to produce tar and other potentially harmful by-products. To avoid smoking tobacco, various smoking substitution systems (or "substitute smoking systems") have been proposed.

Such smoking substitution systems can form part of nicotine replacement therapy aimed at people wishing to quit smoking and overcome their dependence on nicotine.

Smoking substitution systems include electronic systems that allow a user to simulate the act of smoking by producing an aerosol (also called "vapor") that is drawn (inhaled) through the mouth into the lungs and then exhaled. The inhaled aerosol typically contains nicotine and/or flavorings without or with fewer odors and health risks associated with traditional smoking.

Generally, smoking substitution systems are intended to provide a substitute for the habitual behavior of smoking while providing users with an experience and satisfaction similar to that experienced with traditional smoking and combustible tobacco products. Some smoking substitution systems use smoking substitution articles, which are designed to resemble a traditional cigarette and are cylindrical in shape with a mouthpiece at one end.

The popularity and use of smoking-substitution systems has grown rapidly over the past few years. Although originally marketed as an aid to assist habitual smokers wishing to quit smoking tobacco, consumers increasingly view smoking-substitution systems as a desirable lifestyle accessory.

There are several different categories of smoking substitution systems, each of which utilizes a different smoking substitution approach.

One approach for smoking substitution systems is the so-called "heat-not-burn" ("HNB") approach, in which tobacco (not "e-liquid") is heated or warmed to release vapor. The tobacco may be leaf tobacco or reconstituted tobacco. The vapor may contain nicotine and/or flavorings. In the HNB approach, the intention is that the tobacco is heated without being burned, i.e., the tobacco does not undergo combustion.

A typical HNB smoking substitution system may include a device and a consumable. The consumable may include tobacco material. The device and consumable may be configured to be physically coupled together. In use, heat may be applied to the tobacco material by a heating element of the device, and airflow through the tobacco material causes moisture in the tobacco material to be released as vapor. The vapor may also be formed from a carrier in the tobacco material (which may include, for example, propylene glycol and/or vegetable glycerin), as well as volatile compounds released from the tobacco. The released vapor may be entrained in the airflow drawn through the tobacco.

As the vapor passes through the consumable (entrained in the airflow) from the inlet to the mouthpiece (outlet), it cools and condenses to form an aerosol for inhalation by the user. The aerosol typically contains volatile compounds.

In the HNB smoking substitution system, it is believed that heating, as opposed to burning, tobacco material results in fewer or lower amounts of more harmful compounds typically produced during smoking. As a result, the HNB approach can reduce odor and/or health risks that can result through tobacco burning, tobacco combustion, and pyrolytic degradation.

In some cases, the aerosol coming from the mouthpiece (i.e., inhaled by the user) may not be in the desired state. Therefore, it may be desirable to alter one or more characteristics of the aerosol before it is inhaled by the user.

Improved designs of HNB consumables are needed to enhance the user experience and improve the functionality of HNB smoking substitution systems.

This disclosure was devised in light of the above problems.

Most generally, the present disclosure relates to aerosol-forming articles having filter elements of differing hardness, such as smoking substitute articles, such as HNB consumables.

According to a first aspect, there is provided an aerosol-forming article (e.g., a smoking substitute article, such as an HNB consumable) comprising an aerosol-forming substrate and a plurality of filter elements, at least two of the filter elements having different hardnesses from each other.

By providing multiple filter elements of different hardness, vapor filtration performance can be tailored during manufacturing to enhance the user's experience and reduce inhalation of undesirable components of the vapor. The respective hardness of the filter elements can also be used to tailor the resistance to draw (RTD) of the article, with filter elements of higher hardness providing an increased RTD over filter elements of lower hardness.

Optional features are described below. These may be applied alone or in any combination with any aspect.

The aerosol-forming article is preferably a heat-not-burn (HNB) consumable.

The aerosol-forming substrate is capable of being heated to release at least one volatile compound capable of forming an aerosol. The aerosol-forming substrate may be located at the upstream end of the article/consumable.

As used herein, the terms "upstream" and "downstream" are intended to refer to the direction of vapor/aerosol flow, i.e., the downstream end of the article/consumable is the mouth end or outlet where the aerosol exits the article/consumable for inhalation by the user. The upstream end of the article/consumable is the end opposite the downstream end.

To generate an aerosol, the aerosol-forming substrate comprises at least one volatile compound that is intended to be vaporized/aerosolized and that, when inhaled, can provide a recreational and/or medicinal effect to the user. Suitable chemically and/or physiologically active volatile compounds include the group consisting of nicotine, cocaine, caffeine, opiates and opioids, cathine and cathinones, kavalactones, mysticin, beta-carboline alkaloids, salvinorin A, together with any combinations, functional equivalents, and/or synthetic substitutes of the above.

The aerosol-forming substrate may include plant material. Plant materials include Amaranthus dubius, Arctostaphylos va-ursi (Bearberry), Argemone mexicana, Amica, Artemisia vulgaris, Yellow Tees, Gale a zacatechichi, Canavalia maritima (Baybean), Cecropia mexicana (Guamura), Cestrum noctumum, Cynoglossum virginianum (wild co mfrey), Cytisus scoparius, Ｄａｍｉａｎａ、 Ｅｎｔａｄａ ｒｈｅｅｄｉｉ、 Ｅｓｃｈｓｃｈｏｌｚｉａ ｃａｌｉｆｏｍｉｃａ （Ｃａｌｉｆｏｒｎｉａ Ｐｏｐｐｙ）、 Ｆｉｔｔｏｎｉａ ａｌｂｉｖｅｎｉｓ、 Ｈｉｐｐｏｂｒｏｍａ ｌｏｎｇｉｆｌｏｒａ、 Ｈｕｍｕｌｕｓ ｊａｐｏｎｉｃａ （Ｊａｐａｎｅｓｅ Ｈｏｐｓ）、 Ｈｕｍｕｌｕｓ ｌｕｐｕｌｕｓ （Ｈｏｐｓ）、 Ｌａｃｔｕｃａ ｖｉｒｏｓａ （Ｌｅｔｔｕｃｅ Ｏｐｉｕｍ）、 Ｌａｇｇｅｒａ ａｌａｔａ、 Ｌｅｏｎｏｔｉｓ ｌｅｏｎｕｒｕｓ、 Ｌｅｏｎｕｒｕｓ ｃａｒｄｉａｃａ （Ｍｏｔｈｅｒｗｏｒｔ）、 Ｌｅｏｎｕｒｕｓ sibiricus (Honeyweed), Lobelia cardinalis, Lobelia inflata (Indian-tobacco), Lobelia siphilitica, Nepeta catalia (Catnip), Ni cotiana species (Tobacco), Nymphaea alba (White Lily), Nymphaea caerulea (Blue Lily), Opium poppy, Passiflora incamata (Passionf lower), Pedicularis densiflora (Indian Warrior), Pedicularis groenlandica (Elephant's Head), Salvia divinorum, Salvia dorrii (Tobacco Sage), Salvia species (Sage), Scutellaria galericulata, Scutellaria lateriflora, Scutellaria nana, Scutellaria species (Skullcap), Sida acuta (Wireweed), da rhombifolia, Silene capensis, Syzygium At least one plant material selected from the list including: Aralia aromaticum (Clave), Tagetes lucida (Mexican Tarragon), Tarchonanthus camphoratus, Tumera diffusa (Damiana), Verbascum (Mullein), Zamia latifolia (Maconha Brava), together with any combination, functional equivalent, and/or synthetic alternative of the above.

Preferably, the plant material is tobacco. Any type of tobacco may be used, including, but not limited to, flue-cured, burley, Maryland, dark air-cured, oriental, dark fire-cured, perique, and rustica. This also includes blends of the tobaccos mentioned above.

Any suitable part of the tobacco plant may be used, including the leaves, stems, roots, bark, seeds, and flowers.

The tobacco may include one or more of leaf tobacco, stem tobacco, tobacco powder, tobacco dust, tobacco derivatives, expanded tobacco, homogenized tobacco, cut tobacco, extruded tobacco, cut rag tobacco, and/or reconstituted tobacco (e.g., slurry recon or paper recon).

The aerosol-forming substrate may include a homogenous (e.g. paper/slurry recon) tobacco collecting sheet, or collecting strips/strips formed from such a sheet.

In some embodiments, the sheet used to form the aerosol-forming substrate has a basis weight of 100 g/m ² or more, for example 110 g/m ² or more, such as 120 g/m ² or more.

The sheet may have a basis weight of 300 g/m2 or ^less , such as 250 g/m2 ^or less, or 200 g/m2 ^{or less} .

The sheets may have a basis weight of 120 to 190 g/m ² .

The aerosol-forming substrate may comprise at least 50% by weight of plant material, such as at least 60% by weight of plant material, for example about 65% by weight of plant material. The aerosol-forming substrate may comprise up to 80% by weight of plant material, for example up to 75 or 70% by weight of plant material.

The aerosol-forming substrate may include one or more additives selected from humectants, flavorings, fillers, aqueous/non-aqueous solvents, and binders.

Humectants are provided as a source of vapor generation and the resulting vapor helps retain volatile active compounds and increases the visible vapor. Suitable humectants include polyhydric alcohols (e.g., propylene glycol (PG), triethylene glycol, 1,2-butanediol, and vegetable glycerin (VG)) and their esters (e.g., glycerol monoacetate, diacetate, or triacetate). The humectant may be present in the aerosol-forming substrate in an amount of 1-50% by weight.

The humectant content of the aerosol-forming substrate can have a lower limit of at least 1% by weight of the plant material, such as at least 2% by weight, such as at least 5% by weight, such as at least 10% by weight, such as at least 20% by weight, such as at least 30% by weight, or such as at least 40% by weight.

The humectant content of the aerosol-forming substrate may have an upper limit of at most 50% by weight of the plant material, such as at most 40% by weight, such as at most 30% by weight, or such as at most 20% by weight.

Preferably, the humectant content is 1-40% by weight of the aerosol-forming substrate, such as 1-20% by weight.

Suitable binders are known in the art and can act to bind together the components that form the aerosol-forming substrate. Binders can include starch and/or cellulose binders such as methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, and methylcellulose; gums such as xanthan gum, guar gum, gum arabic, and/or locust bean gum; organic acids and their salts such as alginic acid/sodium alginate, agar, and pectin.

Preferably, the binder content is 5-10% by weight of the aerosol-forming substrate, for example about 6-8% by weight.

Suitable fillers are known in the art and can act to enhance the aerosol-forming substrate. Fillers can include fibrous (non-tobacco) fillers such as cellulose fibers, lignocellulosic fibers (e.g., wood fibers), jute fibers, and combinations thereof.

Preferably, the filler content is 5-10% by weight of the aerosol-forming substrate, for example about 6-9% by weight.

The aerosol-forming substrate may comprise an aqueous and/or non-aqueous solvent. In some embodiments, the aerosol-forming substrate has a moisture content of 5-10% by weight, for example 6-9% by weight, such as 7-9% by weight.

The flavorings may be provided in solid or liquid form. The flavorings may include menthol, licorice, chocolate, fruit flavors (including, for example, citrus, cherry, etc.), vanilla, spices (e.g., ginger, cinnamon), and tobacco flavors. The flavorings may be uniformly dispersed throughout the aerosol-forming substrate or may be provided at discrete locations and/or varying concentrations throughout the aerosol-forming substrate.

The aerosol-forming substrate may be formed in a substantially cylindrical shape such that the article/consumable resembles a conventional cigarette. The aerosol-forming substrate may have a diameter of 5-10 mm, for example 6-9 mm or 6-8 mm, for example about 7 mm. The aerosol-forming substrate may have an axial length of 10-15 mm, for example 11-14 mm, such as about 12 or 13 mm.

The aerosol-forming substrate may be at least partially circumscribed by a wrap layer, for example a paper wrap layer. The wrap layer may overlie an inner foil layer or may comprise a paper/foil laminate (foil innermost).

The article/consumable includes at least two filter elements. A terminal filter element may be located at the downstream/mouth end of the article/consumable. An upstream filter element may be located upstream of the downstream axial end but downstream of the aerosol-forming substrate.

The terminal filter element and the upstream filter element may be axially adjacent or spaced apart from one another. The upstream filter element may be at least partially (e.g., entirely) circumscribed by a (paper) wrap layer.

At least one of the filter elements (e.g., the end filter element and/or the upstream filter element) may be constructed from cellulose acetate or polypropylene tow. At least one of the filter elements (e.g., the end filter element and/or the upstream filter element) may be constructed from activated carbon. At least one of the filter elements (e.g., the end filter element and/or the upstream filter element) may be constructed from paper. At least one of the filter elements (e.g., the end filter element and/or the upstream filter element) may be constructed from plant material, e.g., extruded plant material. The or each filter element may be circumscribed by a plug wrap, e.g., a paper plug wrap.

The or each filter element may have a substantially cylindrical shape, the diameter of which substantially corresponds to the diameter of the aerosol-forming substrate (with or without its associated wrap layer).

In some embodiments, the upstream and terminal filter elements have different axial lengths. For example, the axial length of the terminal filter element may be greater than the axial length of the upstream filter element. For example, the axial length of the terminal filter element may be 1 mm or more greater than the axial length of the upstream filter element. The axial length of the terminal filter element may be 2 mm or 3 mm or 4 mm or 5 mm or more greater than the axial length of the upstream filter element.

The axial length of the terminal filter element may be less than 20 mm, for example between 8 and 15 mm, for example between 9 and 13 mm, for example between 10 and 12 mm, such as about 12 mm.

In some embodiments, the upstream filter element can have an axial length of 10 mm or less, and the terminal filter element has an axial length of greater than 10 mm, for example about 12 mm.

The filter element or at least one of the filter elements (e.g., the terminal filter element and/or the upstream filter element) may be a solid filter element. The filter element or at least one of the filter elements (e.g., the terminal filter element and/or the upstream filter element) may be a hollow filter element.

The terminal filter element is preferably a hollow filter element having a greater axial length than the upstream filter element. The upstream filter element may be a hollow filter element.

Providing a shorter upstream filter element results in a greater concentration of volatile compounds (e.g., nicotine) in the terminal filter element due to less condensation of volatile compounds in the upstream filter element. This effect is further enhanced in embodiments where the upstream filter element is a hollow filter element, due to the lack of obstruction in the path through the upstream filter element. In preferred embodiments, increasing the length of the terminal hollow filter provides better mixing (within the pores) of the vapor components (including the increased volatile compound components).

The or each hollow filter element may have a diameter of 1 to 5 mm, for example 2 to 4 mm, or 2 to 3 mm. If the upstream filter element and the terminal filter element are both hollow filter elements, the upstream filter element preferably has a larger diameter than the terminal filter element.

The terminal hollow filter element can have an increased density or increased hardness than the upstream filter element, i.e., the upstream filter element can have an increased porosity than the terminal filter element. This is to increase the flow and mixing of the vapor/aerosol within the hollow pores of the terminal filter element. The increased hardness/reduced porosity of the terminal filter element allows the aerosol/vapor to pass through the terminal filter element and into the axial pores (as it is prevented from passing through the body of the terminal filter element), so that the components in the vapor/aerosol share the same location within the pores, thus increasing mixing. Additionally, increasing the hardness of the terminal filter element can reduce the need for filter plasticizers at the downstream (mouth) end of the article.

The hardness of a filter element can be measured using a standard densitometer, such as a Borgwaldt densitometer DD60A. During such a measurement, the diameter of the filter element is measured, then a crushing load (e.g., 3 kg) is applied, and after a given time, the remaining diameter (parallel to the applied force) is measured. The percent hardness is calculated as the remaining diameter divided by the initial diameter multiplied by 100.

In some embodiments, the percent hardness of the terminal filter element is 3% or more, 4% or more, or 5% or more greater than the hardness of the upstream filter element.

A terminal filter element (the downstream end of the article/consumable) can be joined to an upstream element to form the article/consumable by a circumscribing tipping layer, e.g., a tipping paper layer. The tipping paper can have an axial length greater than the axial length of the terminal filter element, such that the tipping paper completely circumscribing the terminal filter element and the wrap layer surrounding any adjacent upstream elements.

In some embodiments, the article/consumable may include an aerosol cooling element adapted to cool the aerosol generated (by heat exchange) from the aerosol-forming substrate before it is inhaled by the user.

The aerosol cooling element is located downstream from the aerosol-forming substrate. For example, the aerosol cooling element may be between the aerosol-forming substrate and the upstream filter element, and/or between two filter elements. The aerosol cooling element may be at least partially (e.g. completely) circumscribed by a (paper) wrap layer.

The aerosol cooling element may be formed from a plastic material selected from the group consisting of polylactic acid (PLA), polyvinyl chloride (PVC), polyethylene (PE), and polyethylene terephthalate (PET). The aerosol cooling element may be formed from a crimped/collected sheet of material to form a high surface area structure with multiple longitudinal channels to maximize heat exchange and cooling of the aerosol.

The article/consumable may include a spacer element that defines a space or cavity or chamber between the aerosol-forming substrate and the downstream end of the article/consumable. For example, a spacer element may be provided between the aerosol-forming substrate and the upstream filter element, and/or between two filter elements. The spacer acts to allow both cooling and mixing of the aerosol. The spacer element may be a tubular spacer element, and may include, for example, a paper tube. The spacer element may be at least partially (e.g. entirely) circumscribed by a (paper) wrap layer.

The spacer element can have an outer diameter of 5-10 mm, e.g., 6-9 mm or 6-8 mm, e.g., about 7 mm. The spacer element can have an axial length greater than the axial length of the terminal filter element. The spacer element can have an axial length of any of 10-15 mm, e.g., 12-14 mm or 13-14 mm, e.g., about 14 mm.

In a second aspect, there is provided a smoking substitution system comprising an aerosol-forming article according to the first aspect and a device including a heating element.

The device may be an HNB device, i.e. a device adapted to heat an aerosol-forming substrate without combustion.

The device may include a body for housing a heating element. The heating element may include an elongated, e.g., rod, tubular, or blade heating element. The heating element may protrude into or surround a cavity in the body for receiving the article/consumable as described above.

The device (e.g., the main body) may further include a power source, e.g., a (rechargeable) battery, for supplying power to the heating element. The device may further include a control unit for controlling the supply of power to the heating element.

In a third aspect, there is provided a method of using a smoking substitution system according to the second aspect, the method comprising:
Inserting an item/consumable into the device;
and heating the item/consumable using the heating element.

In some embodiments, the method includes inserting the article/consumable into a cavity within the body and penetrating a heating element into the article/consumable as the article/consumable is inserted. For example, the heating element can penetrate an aerosol-forming substrate within the article/consumable.

Those skilled in the art will recognize that, unless mutually exclusive, any feature or parameter described in connection with any one of the above aspects may also be applied to any other aspect. Furthermore, unless mutually exclusive, any feature or parameter described herein may be applied to any aspect and/or may be combined with any other feature or parameter described herein.

So that the invention may be understood and further aspects and features thereof may be realized, embodiments illustrating the principles of the invention will now be discussed in more detail with reference to the accompanying drawings.

FIG. 1 illustrates a first embodiment of an HNB consumable. FIG. 2 illustrates a second embodiment of an HNB consumable. FIG. 2 illustrates a first embodiment of a device forming an HNB system.

As shown in FIG. 1, the HNB consumable 1 includes an aerosol-forming substrate 2 at the upstream end of the consumable 1.

The aerosol-forming substrate includes reconstituted tobacco, which includes nicotine as a volatile compound.

The aerosol-forming substrate 2 comprises 65% by weight tobacco provided in the form of collected shreds produced from a slurry/paper recon tobacco sheet. The tobacco has 20% by weight of a humectant, such as propylene glycol (PG) or vegetable glycerin (VG), attached thereto and has a moisture content of 7-9% by weight. The aerosol-forming substrate further comprises a cellulose pulp filler and a guar gum binder.

The aerosol-forming substrate 2 is formed in a substantially cylindrical shape such that the consumable resembles a conventional cigarette. The aerosol-forming substrate 2 has a diameter of about 7 mm and an axial length of about 12 mm.

The aerosol-forming substrate 2 is circumscribed by a paper wrap layer 3.

The consumable 1 includes an upstream filter element 4 and a downstream (terminal) filter element 5. The two filter elements 4, 5 are spaced apart by a paper tube spacer 6. Both filter elements 4, 5 are formed from cellulose acetate tow and are wrapped with respective paper plug layers (not shown).

Both filter elements have a substantially cylindrical shape. The diameter of the upstream filter 4 corresponds to the diameter of the aerosol-forming substrate 2. The diameter of the terminal filter element 5 is slightly larger and corresponds to the combined diameter of the aerosol-forming substrate 2 and the wrap layer 3. The upstream filter element is shorter in axial length than the terminal filter element, having an axial length of 10 mm compared to 12 mm for the terminal filter element.

The paper tube spacer is longer than each of the two filter elements and has an axial length of approximately 14 mm.

Each filter element 4, 5 is a hollow filter element having longitudinally extending hollow pores. The diameter of the pores in the upstream filter element is slightly larger than the diameter of the pores in the terminal filter element, having a diameter of 3 mm compared to 2 mm for the terminal filter element 5. The porosity of the upstream filter element 4 is greater than the porosity of the terminal filter element 5.

The paper tube spacer 6 and the upstream filter element 4 are circumscribed by the wrap layer 3.

The terminal filter element 5 is joined to the upstream element by a circumscribing paper tip layer 7 to form the consumable. The tip layer 7 surrounds the terminal filter element 5 and has an axial length of about 20 mm, thus overlapping a portion of the paper tube spacer 6.

The terminal filter element 5 has a hardness (95%) greater than the hardness (90%) of the upstream filter element 4.

Figure 2 shows a second embodiment of the consumable 1', which is the same as the first embodiment, except that the wrap layer 3 does not completely circumscribe the paper tube spacer 6, and therefore an annular gap 9 exists between the tip layer 7 and the paper tube spacer 6 downstream of the end of the wrap layer 3.

Figure 3 shows a first embodiment inserted into an HNB device 10 that includes a rod-shaped heating element 20. The heating element 20 protrudes into a cavity 11 within the body 12 of the device.

The consumable 1 is inserted into the cavity 11 of the body 12 of the device 10 so that the heating rod 20 penetrates the aerosol-forming substrate 2. Heating of the reconstituted tobacco in the aerosol-forming substrate 2 is achieved by supplying power to the heating element (e.g., by a rechargeable battery (not shown)). As the tobacco is heated, moisture and volatile compounds (e.g., nicotine) within the tobacco and humectant are released as vapor and are entrained in the airflow generated by inhalation by the user at the terminal filter element 5.

As the vapor cools within the upstream filter element 4 and the paper tube spacer 6, it condenses and forms an aerosol containing volatile compounds for inhalation by the user.

Providing the terminal filter element 5 with a higher hardness than the upstream filter element 4 increases the flow and mixing of the vapor/aerosol within the hollow pores of the terminal filter element 5. The increased hardness/reduced porosity of the terminal filter element 5 allows the aerosol/vapor to enter the axial pores through the terminal filter element 5 (as the passage through the body of the terminal filter element 5 is impeded), which allows the components in the vapor/aerosol to share the same location in the pores, thus increasing mixing. Furthermore, increasing the hardness of the terminal filter element 5 can reduce the need for filter plasticizers at the downstream (mouth) end of the article. The lower hardness/lower density upstream filter element 4 allows more passage of the aerosol/vapor through the body of the upstream filter element, thus filtering harmful particulate matter prior to its delivery in the axial pores of the terminal filter element 5. Furthermore, the hardness of the two filter elements 4, 5 can be used to adjust the RTD of the consumable 1.

The features disclosed in the above description, or in the following claims, or in the accompanying drawings, are appropriately expressed in their specific form, or in terms of means for performing a disclosed function, or a method or process for obtaining a disclosed result, and may be utilized separately or in any combination of such features to realize the invention in its many and varied forms.

While the present invention has been described in conjunction with the exemplary embodiments set forth above, many equivalent modifications and variations will be apparent to those of ordinary skill in the art given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative rather than limiting. Various changes may be made to the described embodiments without departing from the scope of the invention.

For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purpose of improving the understanding of the reader. The inventors do not wish to be bound by any of these theoretical explanations.

All headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unless the context otherwise requires, the words "have," "comprise," and "include," as well as variations such as "having," "comprises," "comprising," and "including," will be understood to imply the inclusion of a stated whole or step, or group of wholes or steps, but not the exclusion of any other whole or step, or group of wholes or steps.

As used herein and in the appended claims, it should be noted that the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. As used herein, ranges may be expressed as "about" one particular value and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, by use of the prefix "about," when values are expressed as approximations, it will be understood that the particular value forms another embodiment. The term "about" in connection with numerical values is optional and means, for example, ±10%.

The words "preferred" and "preferably" are used herein to refer to embodiments of the invention that may provide certain benefits, under some circumstances. It is to be understood, however, that other embodiments may also be preferred, under the same or different circumstances. Thus, reference to one or more preferred embodiments does not mean or imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the disclosure or the claims.

Claims (15)

An aerosol-forming article comprising an aerosol-forming substrate and a plurality of filter elements, at least two of which have different hardnesses. The article of claim 1, which is a heat-not-burn (HNB) consumable. The article of claim 1 or 2, comprising a terminal filter element located at a downstream/mouth end of the article and an upstream filter element located upstream of the terminal filter element. The article of claim 3, wherein the hardness of the terminal filter element is greater than the hardness of the upstream filter element. The article of claim 4, wherein the hardness of the terminal filter element is at least 3% greater than the hardness of the upstream filter element. The article of any one of claims 3 to 5, wherein the axial length of the terminal filter element is greater than the axial length of the upstream filter element. The article of claim 6, wherein the axial length of the terminal filter element is at least 2 mm greater than the axial length of the upstream filter element. The article according to any one of claims 3 to 7, wherein the terminal filter element is a hollow filter element. The article of claim 8, wherein the upstream filter element is a hollow filter element. The article of claim 9, wherein the terminal filter element has an axial hole having a smaller diameter than the axial hole in the upstream filter element. The article of any one of claims 3 to 10, wherein the upstream filter element and the terminal filter element are spaced apart by an aerosol cooling element and/or a spacer element. A system comprising a smoking substitute article according to any one of claims 1 to 11 and a device including a heating element. The system of claim 12, wherein the device includes a body for housing the heating element, the heating element including an elongated heating element. A method of using a system according to claim 12 or 13, comprising the steps of:
Inserting the article into the device;
heating the article using the heating element. 14. The method of claim 13, comprising inserting the article into a cavity in a body of the device and penetrating the heating element into the article as the article is inserted.

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