Aerosol-generating article comprising a hollow tube segment comprising a polyhydroxyalkanoate

Abstract

An aerosol-generating article (10; 100; 310) for generating an inhalable aerosol upon heating is provided, the aerosol-generating article comprising: a strip (12; 114; 312) of an aerosol-generating substrate; a hollow tube segment (14; 120; 320) comprising a fibrous filter material, the hollow tube segment (14; 120; 320) being arranged downstream of the strip (12; 114; 312) and longitudinally aligned with the strip (12; 114; 312); wherein the fibrous filter material comprises fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

Description

[0001] The present invention relates to a hollow tube segment for use in an aerosol-generating article and an aerosol-generating article comprising the hollow tube segment. The present invention also relates to an aerosol-generating system comprising an aerosol-generating device and such an aerosol-generating article.

[0002] Conventional aerosol-generating articles, such as filter cigarettes, typically comprise a cylindrical rod of tobacco cut filler surrounded by a paper wrapper, and a cylindrical filter axially aligned with the wrapped tobacco rod, most often in an end-to-end relationship. The cylindrical filter typically comprises one or more filter segments of fibrous filter material, such as cellulose acetate tow, defined by a paper filter segment wrapper. Conventionally, the wrapped tobacco rod and filter are joined by a tipping wrapper, typically made of an opaque paper material, which surrounds the entire length of the filter and an adjacent portion of the wrapped tobacco rod.

[0003] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than burned are also known in the art. Typically, in such articles, an aerosol is generated by transferring heat from a heat source to a physically separate aerosol-generating substrate or material.

[0004] For example, aerosol-generating articles have been proposed in which the aerosol is generated by electrical heating of an aerosol-generating substrate. Numerous prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol-generating devices in which the aerosol is generated by transferring heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of the heated aerosol-generating article. As another example, aerosol-generating articles are also known in which the aerosol is generated by transferring heat from a combustible fuel element or heat source to the aerosol-generating substrate. The combustible fuel element or heat source can be positioned in contact with the aerosol-generating substrate, within the aerosol-generating substrate, around the aerosol-generating substrate, or downstream of the aerosol-generating substrate.

[0005] During use of such an aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer and are entrained in the air drawn through the aerosol-generating article. When the released compounds cool, they condense to form an aerosol.

[0006] Typically, aerosol-generating articles of the type described may include a mouthpiece comprising a filter segment formed from a porous filter material, such as cellulose acetate. In some known aerosol-generating articles, a hollow tubular segment formed from a filter material, such as cellulose acetate, is provided between the aerosol-generating substrate and the mouth end of the article to impart structural strength to the article.

[0007] A number of aerosol-generating articles have also been described that include hollow tube segments formed from fibrous filter materials. For example, aerosol-generating articles have been disclosed that include, in addition to a strip of aerosol-generating substrate, a support element in the form of a hollow acetate tube. In one particular embodiment, one such aerosol-generating article includes, in a linear arrangement, a strip of aerosol-generating substrate, a hollow acetate tube positioned immediately downstream of the aerosol-generating substrate, an aerosol-cooling element positioned downstream of the hollow acetate tube, and an outer wrapper surrounding the strip, the hollow acetate tube, and the aerosol-cooling element.

[0008] Furthermore, conventional aerosol-generating articles have been proposed in which the filter comprises a hollow tube segment formed of fibrous filter material, preferably combined with and axially aligned with another non-hollow segment formed of fibrous filter material. For example, filter cigarettes have been disclosed in which one such hollow tube segment is positioned at the mouth end of the filter cigarette, such that the cavity defined by the interior of the hollow tube segment is open to the external environment. Filter cigarettes have also been disclosed in which one such hollow tube segment is positioned between non-hollow segments formed of fibrous filter material. The cavity defined by the interior of the hollow tube segment and bounded at its ends by the two non-hollow segments can contain an aerosol-altering substance, such as a sorbent material or a breakable flavor capsule.

[0009] After an aerosol-generating article has been consumed and discarded, it may be desirable for any article components containing filter material to decompose as quickly as possible. However, cellulose acetate and many other commonly used filter materials are not highly biodegradable. However, alternative dispersible or biodegradable materials often fail to provide acceptable filtration efficiency and consumer smoking experience. Furthermore, many known dispersible and biodegradable materials are not suitable for existing manufacturing processes and require significant modifications to existing methods and equipment to make their use commercially viable.

[0010] Furthermore, when used in conventional smoking articles, cellulose acetate has been found to provide relatively high levels of adsorption and capture of water from mainstream smoke. The mainstream smoke delivered to the consumer therefore has a significantly reduced moisture content and, in some cases, may be considered undesirably "dry." This may adversely affect the overall smoking experience.

[0011] It is therefore desirable to provide a new and improved aerosol-generating article having enhanced biodegradability compared to known articles comprising conventional filter materials, such as cellulose acetate. It is also desirable to provide a new and improved aerosol-generating article that provides a smoking experience that is acceptable to consumers, and in particular, an aerosol-generating article that reduces the "dry" smoke effect that is commonly associated with articles comprising cellulose acetate as a filter material.

[0012] It is desirable to provide an aerosol-generating article in which the resistance to draw (RTD) of a filter material segment can be adjusted to obtain an acceptable RTD for the article as a whole. Furthermore, it is desirable to provide an aerosol-generating article that can be efficiently produced in an automated, high-speed manufacturing process without requiring major modifications to existing equipment.

[0013] The present disclosure relates to an aerosol-generating article for generating an inhalable aerosol upon heating. The aerosol-generating article may include a strip of an aerosol-generating substrate and a hollow tubular segment comprising a fibrous filter material. The hollow tubular segment may be arranged longitudinally aligned with the strip. The fibrous filter material may comprise fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer material.

[0014] Furthermore, the present disclosure relates to a hollow tube segment for use in an aerosol-generating article. The hollow tube segment may be formed from a fibrous filter material. The fibrous filter material may comprise fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer material.

[0015] Additionally, the present disclosure relates to a system comprising an aerosol-generating device and an aerosol-generating article for use with the aerosol-generating device. The aerosol-generating article may comprise a strip of an aerosol-generating substrate and a hollow tube segment comprising a fibrous filter material. In the aerosol-generating device, the hollow tube segment may be arranged longitudinally aligned with the strip. The fibrous filter material may comprise fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

[0016] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article comprising: a strip of an aerosol-generating substrate; a hollow tube segment comprising a fibrous filter material, the hollow tube segment being arranged longitudinally aligned with the strip; wherein the fibrous filter material comprises fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

[0017] The term "aerosol-generating article" is used herein in conjunction with the present invention to describe an article in which an aerosol-generating substrate is heated to generate and deliver an aerosol to a consumer. As used herein, the term "aerosol-generating substrate" refers to a substrate that is capable of releasing volatile compounds upon heating to generate an aerosol.

[0018] A conventional cigarette is ignited when a user applies a flame to one end of the cigarette and draws air through the other end. Localized heat provided by the flame and the oxygen in the air drawn through the cigarette causes the end of the cigarette to ignite, and the resulting combustion generates inhalable smoke. In contrast, in heated aerosol-generating articles, an aerosol is generated by heating a flavor-generating substrate, such as a tobacco-based substrate or a substrate containing an aerosol-forming agent and a flavoring agent. Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which an aerosol is generated by heat transfer from a combustible fuel element or heat source to a physically separate aerosol-forming material.

[0019] As used herein, the term "longitudinal" refers to a direction corresponding to the principal longitudinal axis of an aerosol-generating article, which direction extends between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms "upstream" and "downstream" describe the relative position of an element or portion of an element of an aerosol-generating article with respect to the direction in which aerosol is transported through the aerosol-generating article during use.

[0020] As briefly described above, in contrast to existing aerosol-generating articles, articles according to the present invention comprise a hollow tube segment comprising a fibrous filter material, wherein the fibrous filter material comprises fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

[0021] Thus, in the hollow tube segment of the aerosol-generating article according to the present invention, the PHA polymer or copolymer comprises at least a portion of the fibrous filter material. This means that the remainder of the fibrous filter material may comprise materials other than the PHA polymer or copolymer. Furthermore, this means that other components of the hollow tube segment—for example, a filter segment wrapper surrounding the fibrous filter material, or an insert, a non-cuttable object such as a flow restrictor, or an additive delivery material that may be provided at a location along the hollow tube segment, such as a breakable capsule—may comprise materials other than the PHA polymer or copolymer.

[0022] Because fibers containing PHA polymers or copolymers (hereinafter also referred to as "PHA fibers") have a lower hydrophilicity than fibers of an equivalent weight of other filter materials, such as cellulose acetate, the hollow tube segments in aerosol-generating articles according to the present invention have been found to have a significantly lower tendency to absorb water / vapor. Consequently, in those embodiments where the hollow tube segments are used as components of multi-segment filters in conventional smoking articles, the water level in mainstream smoke can be advantageously maintained at a higher level. This directly addresses the "dry smoke" problem often encountered with conventional smoking articles and provides consumers with an improved smoking experience.

[0023] Because PHA fibers have a much higher biodegradability level than other filter materials, such as cellulose acetate fibers, the articles according to the present invention are more biodegradable overall. Furthermore, because PHA fibers are obtained through a natural fermentation process, the aerosol-generating articles according to the present invention also offer improved sustainability for the production process. Furthermore, compared to cylindrical filter segments, the hollow tube segments have a larger exposed surface area, which may further facilitate biodegradation.

[0024] By adjusting parameters such as denier per filament, total denier, cross-sectional shape, etc., the RTD of the filter segment can be adjusted to a desired range for any given filter length or filter design.

[0025] The term "denier per filament" (dpf) corresponds to the weight in grams of a single fiber or filament having a length of 9000 meters. In the present invention, the dpf value thus gives an indication of the thickness of each individual PHA fiber within the filter segment. Denier per filament is expressed in denier, where 1 denier corresponds to 1 gram per 9000 meters.

[0026] The "total denier" of the filter material defines the total weight in grams of 9000 meters of the combined fibers forming the filter material. The total denier of a filter segment thus corresponds to the denier per filament multiplied by the total number of fibers in the filter segment.

[0027] Additionally, the overall weight of the hollow tube segment may be advantageously controlled, which may also aid in the biodegradation of the hollow tube segment and the aerosol-generating article as a whole.

[0028] The PHA properties also result in good filter hardness, which can be further enhanced by surrounding the hollow tube segment with a hard filter segment wrapper.

[0029] Aerosol-generating articles according to the invention comprise a strip of aerosol-generating substrate.

[0030] The strip of aerosol generating substrate can be produced using fragments, thin strips or strips of randomly oriented tobacco material. As an alternative, as has been proposed, for example in international patent application WO-A-2012 / 164009, the strip of aerosol generating substrate can be formed by agglomerated sheets of one or more tobacco materials. Alternative strips of aerosol generating articles formed by thin strips of homogenized tobacco material have also been proposed, which can be formed by casting, rolling, calendering or extruding a mixture comprising granular tobacco and at least one aerosol forming agent to form a sheet of homogenized tobacco material. In addition, the strip of aerosol generating substrate can be formed by thin strips of homogenized tobacco material, which are obtained by extruding a mixture comprising granular tobacco and at least one aerosol forming agent to form a continuous length of homogenized tobacco material.

[0031] The outer diameter of the strip of aerosol-generating substrate is preferably approximately equal to the outer diameter of the aerosol-generating article.

[0032] Preferably, the strip of aerosol-generating substrate has an outer diameter of at least 5 mm. The strip of aerosol-generating substrate may have an outer diameter of between about 5 mm and about 12 mm, for example, between about 5 mm and about 10 mm, or between about 6 mm and about 8 mm. In a preferred embodiment, the strip of aerosol-generating substrate has an outer diameter within 10% of 7.2 mm.

[0033] The strip of aerosol generating substrate may have a length between about 5 mm and about 100 mm. Preferably, the strip of aerosol generating substrate has a length of at least about 5 mm, more preferably at least about 7 mm. In addition, or as an alternative, the strip of aerosol generating substrate preferably has a length of less than about 80 mm, more preferably less than about 65 mm, even more preferably less than about 50 mm. In a particularly preferred embodiment, the strip of aerosol generating substrate has a length of less than about 35 mm, more preferably less than 25 mm, even more preferably less than about 20 mm. In one embodiment, the strip of aerosol generating substrate may have a length of about 10 mm. In a preferred embodiment, the strip of aerosol generating substrate has a length of about 12 mm.

[0034] Preferably, the strip of aerosol-generating substrate has a substantially uniform cross-section along the length of the strip.Particularly preferably, the strip of aerosol-generating substrate has a substantially circular cross-section.

[0035] In a preferred embodiment, the aerosol generating substrate comprises the gathering sheet material of one or more homogenized tobacco materials.Preferably, the sheet material of one or more homogenized tobacco materials is textured.As used herein, term " textured sheet material " represents the sheet material that has been curled, embossed, gravure, perforated or otherwise deformed.The textured sheet material that is used for homogenized tobacco material of the present invention can comprise a plurality of indentations, protrusions, perforations or its combination that are spaced apart.According to particularly preferred embodiments of the present invention, the strip of aerosol generating substrate comprises the gathering curled sheet material of the homogenized tobacco material that is limited by wrapper.

[0036] As used herein, the term "curled sheet" is intended to be synonymous with the term "corrugated sheet" and refers to a sheet having a plurality of substantially parallel ridges or corrugations. Preferably, the curled sheet of homogenized tobacco material has a plurality of ridges or corrugations that are substantially parallel to the cylindrical axis of the rod according to the present invention. This advantageously promotes the gathering of the curled sheet of homogenized tobacco material to form a rod. However, it will be appreciated that the curled sheet for the homogenized tobacco material of the present invention may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that are arranged at an acute angle or an obtuse angle to the cylindrical axis of the rod. The sheet of homogenized tobacco material for the rod of the present invention's article can be substantially uniformly textured over its substantially entire surface. For example, a curled sheet of homogenized tobacco material for the manufacture of a rod for an aerosol-generating article according to the present invention can comprise a plurality of substantially parallel ridges or corrugations that are substantially uniformly spaced apart across the width of the sheet.

[0037] Sheets or webs of homogenized tobacco material used in the present invention can have a tobacco content of at least about 40 weight percent on a dry weight basis, more preferably at least about 60 weight percent on a dry weight basis, more preferably at least about 70 weight percent on a dry weight basis, and most preferably at least about 90 weight percent on a dry weight basis.

[0038] The sheet or web of homogenized tobacco material used in the aerosol-generating substrate may comprise one or more intrinsic binders (i.e., tobacco endogenous binders), one or more non-intrinsic binders (i.e., tobacco exogenous binders), or combinations thereof to help agglomerate the particulate tobacco. Alternatively or additionally, the sheet of homogenized tobacco material used in the aerosol-generating substrate may comprise other additives, including but not limited to tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorings, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0039] Suitable external binders for inclusion in sheets or webs of homogenized tobacco material for use in an aerosol-generating substrate are known in the art and include, but are not limited to, gums such as guar gum, xanthan gum, gum arabic, and locust bean gum; cellulosic binders such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose; polysaccharides such as starch; organic acids such as alginic acid; conjugate base salts of organic acids such as sodium alginate, agar, and pectin; and combinations thereof.

[0040] Suitable non-tobacco fibers for inclusion in a sheet or web of homogenized tobacco material for use in an aerosol-generating substrate are known in the art and include, but are not limited to, cellulose fibers, softwood fibers, hardwood fibers, jute fibers, and combinations thereof. Prior to inclusion in a sheet of homogenized tobacco material for use in an aerosol-generating substrate, the non-tobacco fibers may be processed by suitable methods known in the art, including, but not limited to, mechanical pulping, refining, chemical pulping, bleaching, sulfate pulping, and combinations thereof.

[0041] The substrate for heated aerosol-generating articles typically contains an "aerosol-former," i.e., a compound or mixture of compounds that promotes aerosol formation during use and preferably substantially resists thermal degradation at the operating temperature of the aerosol-generating article. Examples of suitable aerosol-formers include: polyols, such as propylene glycol, triethylene glycol, 1,3-butylene glycol, and glycerol; esters of polyols, such as glycerol monoacetate, glycerol diacetate, or glycerol triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol-formers are polyols or mixtures thereof, such as propylene glycol, triethylene glycol, 1,3-butylene glycol, and most preferably glycerol.

[0042] Preferably, the aerosol-generating substrate comprises at least 10% by weight of an aerosol-forming agent, more preferably at least 12% by weight of an aerosol-forming agent, more preferably at least about 15% by weight of an aerosol-forming agent. Alternatively or additionally, the aerosol-generating substrate preferably comprises no more than 30% by weight of an aerosol-forming agent, more preferably no more than about 25% by weight of an aerosol-forming agent, more preferably no more than about 20% by weight of an aerosol-forming agent. For example, the aerosol-generating substrate may comprise from about 10% to about 30% by weight of an aerosol-forming agent, or from about 12% to about 25% by weight of an aerosol-forming agent, or from about 15% to about 20% by weight of an aerosol-forming agent. In a particularly preferred embodiment, the aerosol-generating substrate comprises about 18% by weight of an aerosol-forming agent.

[0043] In an aerosol-generating article according to the present invention, the filter segment is formed of a fibrous filter material comprising fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer. Preferably, the fibrous filter material comprises at least about 85% by weight of fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

[0044] PHAs are a family of polyhydroxyesters of 3-, 4-, 5-, and 6-hydroxyalkanoic acids that are produced by a variety of bacterial species under nutrient-limited conditions with excess carbon and are present as discrete cytoplasmic inclusions within bacterial cells. Due to their excellent biocompatibility, PHAs have been proposed for use in a wide range of biomedical applications, including drug delivery systems and tissue engineering scaffolds.

[0045] PHA molecules are typically composed of 600 to 35,000 (R)-hydroxy fatty acid monomer units. Depending on the total number of carbon atoms within the PHA monomers, PHAs can be classified as short-chain-length PHAs (scl-PHA; 3 to 5 carbon atoms), medium-chain-length PHAs (mcl-PHA; 6 to 14 carbon atoms), or long-chain-length PHAs (lcl-PHA; 15 or more carbon atoms).

[0046] The first and most common PHA is poly(β-hydroxybutyrate) (PHB). The next member of the PHA family, which has ethyl side groups, is poly(3-hydroxyvalerate) or PHV. The presence of ethyl groups (HV units) instead of the methyl groups of PHB gives PHV greater flexibility and lower crystallinity than PHB.

[0047] Preferably, in the aerosol-generating article according to the present invention, the hollow tube segment comprises at least about 25% by weight of a PHA polymer or copolymer. More preferably, the hollow tube segment comprises at least about 50% by weight of a PHA polymer or copolymer. Even more preferably, the hollow tube segment comprises at least about 60% by weight of a PHA polymer or copolymer. In particularly preferred embodiments, the hollow tube segment comprises at least about 70% by weight of a PHA polymer or copolymer, or even at least about 80% by weight of a PHA polymer or copolymer. In some highly preferred embodiments, the hollow tube segment comprises at least about 85% by weight of a PHA polymer or copolymer. More preferably, the PHA polymer or copolymer is one or more of polyhydroxypropionate, polyhydroxyvalerate, polyhydroxybutyrate, polyhydroxyhexanoate and polyhydroxyoctanoate. In a particularly preferred embodiment, the PHA compound is poly(3-hydroxybutyrate).

[0048] Even more preferably, the hollow tube segment comprises at least about 90% by weight of a PHA polymer or copolymer. Without wishing to be bound by theory, it is understood that a higher PHA content in the hollow tube segment is generally associated with improved biodegradability of the hollow tube segment and the aerosol-generating article as a whole.

[0049] More preferably, the fibrous filter material comprises at least about 91% by weight of a PHA polymer or copolymer, or at least about 92% by weight of a PHA polymer or copolymer, or at least about 93% by weight of a PHA polymer or copolymer, or at least about 94% by weight of a PHA polymer or copolymer. In some particularly preferred embodiments, the fibrous filter material comprises at least about 95% by weight of a PHA polymer or copolymer.

[0050] The remainder of the fibers within the PHA filter segment may comprise any suitable material. Suitable fiber materials will be known to the skilled person and include, but are not limited to, polylactic acid (PLA) and cellulose acetate.

[0051] In some embodiments, the fiber filter material of the hollow tube segment may include some cellulose acetate. Without wishing to be bound by theory, it is understood that a certain amount of cellulose acetate in the hollow tube segment can impart desired filtration and mechanical properties to the hollow tube segment, as well as facilitate the manufacture of the hollow tube segment.

[0052] In certain embodiments, the fibrous filter material of the hollow tube segment comprises at least about 5% by weight cellulose acetate. For example, the fibrous filter material may comprise at least about 6% by weight cellulose acetate, or at least about 7% by weight cellulose acetate, or at least about 8% by weight cellulose acetate, or at least about 9% by weight cellulose acetate. In some embodiments, the fibrous filter material comprises at least about 10% by weight cellulose acetate.

[0053] In aerosol-generating articles according to the present invention, the fibrous filter material preferably comprises less than about 15% by weight of cellulose acetate.

[0054] In some embodiments, the fibrous filter material of the hollow tube segment comprises less than about 5% by weight of cellulose acetate, preferably less than 3% by weight of cellulose acetate, more preferably less than 1% by weight of cellulose acetate, and even more preferably less than 0.1% by weight of cellulose acetate. This may advantageously further contribute to enhancing the biodegradability of the hollow tube segment and the aerosol-generating article as a whole.

[0055] Preferably, the aerosol-generating article according to the present invention comprises less than or equal to about 10% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article. More preferably, the aerosol-generating article according to the present invention comprises less than or equal to about 7% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article. Even more preferably, the aerosol-generating article according to the present invention comprises less than or equal to about 5% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article. This advantageously indicates that not only the hollow tube segment has a low or zero content of cellulose acetate, but also any other article components containing fibrous filter material contain little or no cellulose acetate. Embodiments of the aerosol-generating article according to the present invention having such a low cellulose acetate content exhibit particularly advantageous biodegradability properties.

[0056] In some preferred embodiments, aerosol-generating articles according to the present invention comprise less than or equal to about 3% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article. More preferably, aerosol-generating articles according to the present invention comprise less than or equal to about 2% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article. Even more preferably, aerosol-generating articles according to the present invention comprise less than or equal to about 1% by weight of cellulose acetate, measured relative to the total weight of the aerosol-generating article.

[0057] In some highly preferred embodiments, aerosol-generating articles according to the present invention are substantially free of cellulose acetate.

[0058] In some embodiments, the fibrous filter material further comprises at least one biodegradable polymer selected from the group consisting of starch, polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), thermoplastic starch and thermoplastic starch blends (TPS), polycaprolactone (PCL), polyglycolide (PGA), polyvinyl alcohol (PVOH / PVA), viscose, regenerated cellulose, polysaccharides, cellulose acetate with a degree of substitution (DS) of less than 2.1, polyamides, protein-based biopolymers, chitosan-chitin-based biopolymers, and combinations thereof.

[0059] The present inventors have found that including one or more of these ingredients in the blend of fibrous material from which the filter segment is formed also helps to enhance the biodegradability of the filter segment and the aerosol-generating article as a whole.

[0060] Additionally, while it has previously been found to be technically challenging to produce filaments or fibers containing PHAs using existing techniques and equipment, the present inventors have surprisingly discovered that when PHAs are combined in a blend as described above, filaments or fibers incorporating high levels of PHAs can be produced because this makes it easier to form filaments by spinning techniques.

[0061] In some embodiments, the fibrous filter material comprises at least about 5% by weight of one such additional biodegradable polymer. In a preferred embodiment, the fibrous filter material comprises at least about 10% by weight of one such additional biodegradable polymer. More preferably, the fibrous filter material comprises at least about 11% by weight, or at least 12% by weight, or at least 13% by weight, or at least 14% by weight of one such additional biodegradable polymer. Even more preferably, the fibrous filter material comprises at least about 15% by weight of one such additional biodegradable polymer.

[0062] In a particularly preferred embodiment, the at least one biodegradable polymer is one or more of PBAT, PCL, and PBS. Without wishing to be bound by theory, the present inventors have found that the use of one or more of these selected biodegradable polymers can help improve the mechanical, thermal, and morphological properties of the polymer mixture. In particular, the combination of PBAT and PBS has been found to provide particularly well-balanced mechanical properties, particularly in terms of tensile strength and elongation.

[0063] In some embodiments, the fibrous filter material comprises at least about 3% by weight of a plasticizer selected from triacetin, triethylene glycol diacetate (TEGDA), ethylene vinyl acetate, polyvinyl alcohol, starch, or combinations thereof.

[0064] In some embodiments, the fibrous filter material further comprises a water-based binder. This has the effect of structurally reinforcing the structure of the hollow tube segment. For example, compounds such as starch binders, methylcellulose, or polyvinyl acetate can be used for this purpose.

[0065] Preferably, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of at least about 1. More preferably, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of at least about 2. Even more preferably, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of at least about 3.2.

[0066] In a preferred embodiment, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of less than or equal to about 10. More preferably, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of less than or equal to about 7.5. Even more preferably, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of less than or equal to about 5.

[0067] In some embodiments, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of about 1 to about 10, more preferably about 2 to about 10, and even more preferably about 3.2 to about 10. In other embodiments, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of about 1 to about 7.5, more preferably about 2 to about 7.5, and even more preferably about 3.2 to about 7.5. In further embodiments, the fibrous filtration material of the hollow pipe segment comprises a plurality of fibers comprising a PHA polymer or copolymer and having a denier per filament of about 1 to about 5, more preferably about 2 to about 5, and even more preferably about 3.2 to about 5.

[0068] Without wishing to be bound by theory, the present inventors have found that when the hollow tube segment is formed from PHA fibers having a relatively low dpf between 1.5 and 3.2, the hollow tube segment exhibits a particularly low RTD, which may be desirable for certain aerosol-generating article designs. Such a low dpf range will also advantageously reduce the overall weight of the hollow tube segment, which can further significantly improve the biodegradability of the aerosol-generating article.

[0069] Preferably, the fibers comprising the PHA polymer or copolymer of the filter segment are crimped.

[0070] The transverse cross-sectional shape of the PHA fibers can be varied, for example, to control the external surface area of ​​the fibers within the hollow tube segment. By controlling the external surface area of ​​the PHA fibers, the total surface area of ​​the PHA fibers exposed to the aerosol as the aerosol passes through the hollow tube segment can also be controlled. This, in turn, can, to a certain extent, control the filtration properties of the PHA fibers, for example, the amount of water adsorbed by the fibers in conventional combustible smoking articles.

[0071] In some embodiments, the PHA fibers have a substantially circular cross-section. In such embodiments, the total external surface area of ​​the PHA fibers within the hollow tube segment is preferably between about 0.15 m2 / g and about 0.30 m2 / g.

[0072] In alternative embodiments, the PHA fibers have a Y-shaped cross-section. In such embodiments, the total external surface area of ​​the PHA fibers within the hollow tube segment is preferably between about 0.15 m2 / g and about 0.55 m2 / g. More preferably, the total external surface area of ​​the PHA fibers within the hollow tube segment is between about 0.2 m2 / g and about 0.5 m2 / g, and even more preferably, between about 0.25 m2 / g and about 0.45 m2 / g.

[0073] In some embodiments, the hollow tube segment may contain one or more additives for reducing certain components of mainstream smoke. For example, the filter segment preferably contains an additive for reducing phenol and phenol derivatives. […]

[0074] Combinations of PHA with additives such as PEG for reducing phenolic compounds from mainstream smoke have been found to be particularly effective. PHA fibers generally provide good filtration efficiency for undesirable smoke components but are less effective at removing phenolic compounds. By introducing compounds that will specifically reduce the levels of phenolic compounds in mainstream smoke, the filtration capacity of the hollow tube segments of aerosol-generating articles according to the present invention can be further optimized, particularly when using the hollow tube segments described above as components of multi-component filters in combustible smoking articles such as filter cigarettes. This, in turn, improves the sensory properties of the aerosol delivered to the consumer.

[0075] In a particularly preferred embodiment, the hollow tube segment further comprises at least about 5% by weight polyethylene glycol, based on the total weight of the filter material. Preferably, the hollow tube segment comprises no more than 10% by weight polyethylene glycol, based on the total weight of the filter material.

[0076] As described above, it has been found that PHA fibers absorb less water from mainstream smoke than an equivalent weight of cellulose acetate fibers due to their lower affinity for water. As demonstrated in the Examples below, the amount of water absorbed by a PHA filter segment was significantly lower than the amount of water absorbed by a comparative filter segment formed from an equal weight of cellulose acetate fibers.

[0077] For example, when exposed to water in liquid form, the hollow tube segments of the aerosol-generating articles of the present invention preferably absorb less than half the amount of water that a corresponding hollow tube segment formed from cellulose acetate fibers absorbs under the same conditions.

[0078] The reduced water absorption of the PHA fibers in the hollow tube segments of the present invention compared to cellulose acetate results in a higher water content in the mainstream smoke delivered from the aerosol-generating article during use.

[0079] For example, a combustible smoking article comprising a filter having PHA fibers according to the present invention collects at least 10% higher, and preferably at least 15% higher, water in mainstream smoke during smoking under ISO conditions than a corresponding combustible smoking article comprising a filter segment having cellulose acetate tow during smoking under the same conditions.

[0080] Aerosol-generating articles comprising filters comprising PHA hollow tube segments are therefore able to deliver mainstream smoke having higher moisture levels, which is more sensory acceptable to consumers. In particular, the "dry smoke" effect that may be experienced during smoking of aerosol-generating articles having conventional cellulose acetate filters can be advantageously reduced.

[0081] The fibers comprising the PHA polymer or copolymer of the filter segment can be produced by one of several techniques, including melt spinning, gel spinning, and electrospinning. Preferably, the fibers comprising the PHA polymer or copolymer of the filter segment of the aerosol-generating article according to the present invention are produced by melt spinning. Melt spinning is often considered the most economical spinning process because there is no need to recover or evaporate the solvent, in stark contrast to solution spinning. In addition, the spinning rate using melt spinning is generally quite high, which is advantageous in terms of overall productivity and manufacturing efficiency.

[0082] In this method, the viscous melt of polymer or polymer blend is extruded into the chamber by the spinneret that contains many holes, and here, a stream of cold air or gas is directed onto the surface of the long filaments emitted from the spinneret. When air hits the long filaments, the long filaments solidify and are collected on, for example, a take-up wheel. The melt spinning method is advantageously characterized by the long filament cross-sectional geometry that limits and various fineness and filament count are provided. By increasing the number of openings in the spinneret, high spinning capacity can be realized, which is difficult to match with other spinning methods.

[0083] Preferably, in aerosol-generating articles according to the invention, the hollow tube segment does not substantially affect the overall RTD of the aerosol-generating article.

[0084] Therefore, in an aerosol-generating article according to the present invention, the overall RTD of the article preferably depends essentially on the RTD of the strip and may also depend on the RTD of optional additional components such as the mouthpiece or filter segment, because a significant proportion of the total volume of the hollow tube segment is essentially empty and the hollow tube segment therefore only slightly affects the overall RTD.

[0085] In practice, the hollow tube segment may be adapted to produce an RTD of about 0 mm H2O (about 00 Pa) to about 20 mm H2O (about 200 Pa). Preferably, the hollow tube segment is adapted to produce an RTD of about 0 mm H2O (about 00 Pa) to about 10 mm H2O (about 100 Pa).

[0086] The aerosol-generating article preferably has an overall RTD of less than about 90 mm H2O (about 900 Pa). More preferably, the aerosol-generating article has an overall RTD of less than about 80 mm H2O (about 800 Pa). Even more preferably, the aerosol-generating article has an overall RTD of less than about 70 mm H2O (about 700 Pa).

[0087] Preferably, the aerosol-generating article has an overall RTD of at least about 30 mm H2O (about 300 Pa). More preferably, the aerosol-generating article has an overall RTD of at least about 40 mm H2O (about 400 Pa). Even more preferably, the aerosol-generating article has an overall RTD of at least about 50 mm H2O (about 500 Pa).

[0088] In some embodiments, the aerosol-generating article has an overall RTD of about 30 mm HO (about 300 Pa) to about 90 mm HO (about 900 Pa), preferably about 40 mm HO (about 400 Pa) to about 90 mm HO (about 900 Pa), more preferably about 50 mm HO (about 500 Pa) to about 90 mm HO (about 900 Pa). In other embodiments, the aerosol-generating article has an overall RTD of about 30 mm HO (about 300 Pa) to about 80 mm HO (about 800 Pa), preferably about 40 mm HO (about 400 Pa) to about 80 mm HO (about 800 Pa), more preferably about 50 mm HO (about 500 Pa) to about 80 mm HO (about 800 Pa). In a further embodiment, the aerosol-generating article has an overall RTD of about 30 mm H2O (about 300 Pa) to about 70 mm H2O (about 700 Pa), preferably about 40 mm H2O (about 400 Pa) to about 70 mm H2O (about 700 Pa), and more preferably about 50 mm H2O (about 500 Pa) to about 70 mm H2O (about 700 Pa).

[0089] The RTD of an aerosol-generating article may be assessed as the negative pressure that must be applied to the downstream end of the article in order to maintain a steady air volume flow rate of 17.5 ml / s through the article under the test conditions as defined in ISO 3402. The RTD values ​​listed above are intended to be measured on the aerosol-generating article itself (i.e., without the article being inserted into an aerosol-generating device) and, if a ventilation zone is provided in the article, without blocking any perforations in the ventilation zone.

[0090] In other embodiments, the aerosol-generating article has an overall RTD of at least about 150 mm H20 (about 1500 Pa), preferably at least about 200 mm H20 (about 2000 Pa), more preferably at least about 250 mm H20 (about 2500 Pa).

[0091] Furthermore, it has been found that hollow tube segments comprising PHA fibers according to the present invention provide good stability in terms of RTD, which means that high variability in RTD can be advantageously avoided. For example, within a sample of 20 aerosol-generating articles according to the present invention, the standard deviation from the target RTD was typically between 2% and 10%, more preferably between 2% and 5%.

[0092] The hollow tube segment preferably has a wall thickness of at least about 0.3 mm. More preferably, the hollow tube segment has a wall thickness of at least about 0.4 mm. Even more preferably, the hollow tube segment has a wall thickness of at least about 0.5 mm.

[0093] Preferably, the hollow tube segment has a wall thickness of less than or equal to about 1.9 mm. More preferably, the hollow tube segment has a wall thickness of less than or equal to about 1.5 mm. Even more preferably, the hollow tube segment has a wall thickness of less than or equal to about 1.2 mm. Particularly preferably, the hollow tube segment has a wall thickness of less than or equal to about 0.9 mm.

[0094] In certain embodiments, the hollow tube segment has a wall thickness of about 0.3 mm to about 1.9 mm, preferably about 0.4 mm to about 1.9 mm, more preferably about 0.5 mm to about 1.9 mm. In some embodiments, the hollow tube segment has a wall thickness of about 0.3 mm to about 1.5 mm, preferably about 0.4 mm to about 1.5 mm, more preferably about 0.5 mm to about 1.5 mm. In other embodiments, the hollow tube segment has a wall thickness of about 0.3 mm to about 1.2 mm, preferably about 0.4 mm to about 1.2 mm, more preferably about 0.5 mm to about 1.2 mm. In further embodiments, the hollow tube segment has a wall thickness of about 0.3 mm to about 0.9 mm, preferably about 0.4 mm to about 0.9 mm, more preferably about 0.5 mm to about 0.9 mm. In a particularly preferred exemplary embodiment, the hollow tube segment has a wall thickness of about 0.6 mm.

[0095] In some embodiments, the hollow tube segment may generally have a length of at least about 4 mm. Preferably, the hollow tube segment has a length of at least about 5 mm. More preferably, the hollow tube segment has a length of at least about 7 mm. Even more preferably, the hollow tube segment has a length of at least about 10 mm.

[0096] In certain embodiments, the length of the hollow tube segment is less than or equal to about 35 mm. Preferably, the length of the hollow tube segment is less than or equal to about 25 mm. More preferably, the length of the hollow tube segment is less than or equal to about 20 mm. Even more preferably, the length of the hollow tube segment is less than or equal to about 15 mm.

[0097] In a preferred embodiment, the length of the hollow tube segment is from about 4 mm to about 35 mm. Preferably, the length of the hollow tube segment is from about 5 mm to about 35 mm. More preferably, the length of the hollow tube segment is from about 7 mm to about 35 mm. Even more preferably, the length of the hollow tube segment is from about 10 mm to about 35 mm.

[0098] In certain other embodiments, the length of the hollow tube segment is from about 4 mm to about 25 mm. Preferably, the length of the hollow tube segment is from about 5 mm to about 25 mm. More preferably, the length of the hollow tube segment is from about 7 mm to about 25 mm. Even more preferably, the length of the hollow tube segment is from about 10 mm to about 25 mm.

[0099] In other embodiments, the length of the hollow tube segment is from about 4 mm to about 20 mm. Preferably, the length of the hollow tube segment is from about 5 mm to about 20 mm. More preferably, the length of the hollow tube segment is from about 7 mm to about 20 mm. Even more preferably, the length of the hollow tube segment is from about 10 mm to about 20 mm.

[0100] In a further embodiment, the length of the hollow tube segment is from about 4 mm to about 15 mm. Preferably, the length of the hollow tube segment is from about 5 mm to about 15 mm. More preferably, the length of the hollow tube segment is from about 7 mm to about 15 mm. Even more preferably, the length of the hollow tube segment is from about 10 mm to about 15 mm.

[0101] Preferably, in aerosol-generating articles according to the present invention, the hollow tube segments have an average radial hardness of at least about 80%, more preferably at least about 85%, and even more preferably at least about 90%. The hollow tube segments are thus able to provide a desired level of hardness to the aerosol-generating article that is comparable to that provided by conventional cellulose acetate hollow tube segments.

[0102] If desired, the radial stiffness of the hollow tube segment of the aerosol-generating article according to the present invention can be further increased by surrounding the hollow tube segment with a hard filter segment package, for example, a filter segment package having a basis weight of at least about 80 grams per square meter (gsm), or at least about 100 gsm, or at least about 110 gsm.

[0103] As used herein, the term "radial stiffness" refers to the resistance to compression in a direction transverse to the longitudinal axis of the hollow tube segment. The radial stiffness of an aerosol-generating article around a hollow tube segment can be determined by applying a load across the article at a location transverse to the longitudinal axis of the article and measuring the average (mean) indentation diameter of the article. The radial stiffness is given by the following formula:

[0104]

[0105] Among them D S is the original (undepressed) diameter, and D d It is the diameter of the indentation after a set load is applied for a set duration. The harder the material, the closer the hardness is to 100%.

[0106] To determine the hardness of a portion of an aerosol article (such as a hollow tube segment), the aerosol-generating articles should be aligned parallel in a plane, and the same portion of each aerosol-generating article to be tested should be subjected to a set load for a set duration. This test is performed using a known DD60A densitometer device (manufactured and commercially available by Heinr. Borgwaldt GmbH, Germany) equipped with a measuring head for an aerosol-generating article (such as a cigarette) and equipped with an aerosol-generating article container.

[0107] The load is applied using two load-applying cylindrical rods that extend simultaneously across the diameter of all aerosol-generating articles. According to the standard test method for this instrument, the test should be performed so that twenty points of contact occur between the aerosol-generating articles and the load-applying cylindrical rods. In some cases, the hollow tube segments to be tested may be long enough that only ten aerosol-generating articles are required to form twenty points of contact, with each smoking article contacting two load-applying rods (because they are long enough to extend between these rods). In other cases, if the hollow tube segments are too short to achieve this, twenty points of contact should be formed using twenty aerosol-generating articles, with each aerosol-generating article contacting only one of the load-applying rods, as discussed further below.

[0108] Two further fixed cylindrical rods are located beneath the aerosol-generating article to support the aerosol-generating article and to counteract the loads applied by each of the load-applying cylindrical rods.

[0109] For standard operating procedures for such devices, a total load of 2 kg is applied for a duration of 20 seconds. After 20 seconds have elapsed (and while the load is still being applied to the smoking article), the depression in the load-applying cylindrical rod is determined and then used to calculate the hardness according to the above formula. The temperature is maintained in the range of 22 degrees Celsius ± 2 degrees. The above test is known as the DD60A test. The standard way to measure filter hardness is when the aerosol-generating article has not yet been consumed. Additional information on the measurement of average radial hardness can be found, for example, in U.S. Published Patent Application Publication No. 2016 / 0128378.

[0110] Aerosol-generating articles according to the invention may comprise one or more further components, which may be assembled together with the strip of aerosol-generating substrate and with the hollow tube segment in the same packaging.

[0111] Examples of such further elements include a mouthpiece filter segment, a cooling element adapted to facilitate cooling of the aerosol before reaching the mouthpiece, and the like.

[0112] For example, the mouthpiece may include a filter segment, which is a filter segment of filter material. The mouthpiece may particularly include a filter segment of fibrous filter material. Suitable filter materials are known in the art and include, but are not limited to: fibrous filter materials such as cellulose acetate tow, viscose fibers, polylactic acid (PLA) fibers, and paper; adsorbents such as activated alumina, zeolites, molecular sieves, and silica gel; and combinations thereof.

[0113] In some preferred embodiments, the fibrous filter material used to form the mouthpiece may be the same fibrous filter material containing a PHA-containing polymer or copolymer as described above for the hollow tube segment of the present invention. This may be particularly advantageous because the desirable effects associated with the fibrous filter material containing a PHA-containing polymer or copolymer in terms of biodegradability and water absorption properties also extend to the mouthpiece filter segment. Thus, an aerosol-generating article having particularly advantageous properties may be provided.

[0114] Additionally, the filter segment of the mouthpiece may also contain one or more aerosol modifiers. Suitable aerosol modifiers are known in the art and include, but are not limited to, flavorings such as, for example, menthol.

[0115] In some embodiments, the hollow tube segment can be used at the downstream end of the aerosol-generating article, axially aligned with the mouthpiece filter segment, preferably immediately adjacent to the downstream end of the mouthpiece filter segment. In such embodiments, the hollow tube segment defines a mouth-end recess downstream of the filter material filter segment. Thus, the hollow tube segment forms a cavity at the mouth-end that is open to the external environment at the downstream end of the aerosol-generating article.

[0116] In such an embodiment, the filter segment of the mouthpiece may generally have a length of less than or equal to about 30 mm. Preferably, the length of the filter segment is less than or equal to about 27 mm. More preferably, the length of the filter segment is less than or equal to about 25 mm. Even more preferably, the length of the filter segment is less than or equal to about 20 mm.

[0117] In such an embodiment, the length of the filter segment is preferably from about 5 mm to about 30 mm, more preferably from about 10 mm to about 30 mm, even more preferably from about 15 mm to about 30 mm, and most preferably from about 20 mm to about 30 mm. Alternatively, in such an embodiment, the length of the filter segment may be from about 4 mm to about 27 mm, preferably from about 5 mm to about 27 mm, more preferably from about 10 mm to about 27 mm, even more preferably from about 15 mm to about 27 mm, and most preferably from about 20 mm to about 27 mm. Alternatively, in such an embodiment, the length of the filter segment may be from about 4 mm to about 25 mm, preferably from about 5 mm to about 25 mm, more preferably from about 10 mm to about 25 mm, even more preferably from about 15 mm to about 30 mm, and most preferably from about 20 mm to about 25 mm.

[0118] The filter segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. Preferably, the filter segment has an outer diameter of at least 5 mm. The filter segment may have an outer diameter of from about 5 mm to about 12 mm, for example from about 5 mm to about 10 mm or from about 6 mm to about 8 mm. In a preferred embodiment, the filter segment has an outer diameter within 10% of 7.2 mm.

[0119] In some embodiments, the mouthpiece comprises a single filter segment as described above. In other embodiments, the aerosol-generating article may comprise one or more additional filter segments. In some preferred embodiments, each of the filter segments of the mouthpiece comprises a PHA polymer or copolymer as described above.

[0120] Alternatively, a filter segment comprising a PHA polymer or copolymer may be combined with one or more axially aligned filter segments formed from a fibrous filter material that does not contain PHA-containing fibers. Alternatively or additionally, a filter segment comprising a PHA polymer or copolymer may be combined with a tubular element formed from a cardboard tube.

[0121] The mouthpiece filter segment of an aerosol-generating article according to the present invention may optionally comprise a flavoring agent. The flavoring agent may be introduced using a variety of different means, which will be known to the skilled person. For example, the flavoring agent may be introduced in the form of capsules, which may be provided in the filter segment comprising the PHA polymer or copolymer.

[0122] For example, in a preferred embodiment, the aerosol-generating article is arranged in a linear order and includes a first filter segment of filter material, a strip of an aerosol-generating substrate located immediately downstream of the first filter segment of filter material, a hollow tube segment as described above with a supporting function located immediately downstream of the strip, a second filter segment of filter material located downstream of the hollow tube segment, and an outer wrapper surrounding the first filter segment, the strip, the support element, and the second filter segment.

[0123] The present invention will now be further described with reference to the accompanying drawings, in which:

[0124] Figure 1 shows a schematic longitudinal cross-sectional view of an aerosol-generating article according to a first embodiment of the invention, the article being to be used with an aerosol-generating device comprising a heater element;

[0125] Figure 2 shows a schematic longitudinal cross-sectional view of an aerosol-generating article according to a second embodiment of the invention, the article comprising an integral heat source;

[0126] Figure 3 shows a schematic longitudinal cross-sectional view of an aerosol-generating article according to a third embodiment of the invention; and

[0127] Figure 4 A schematic longitudinal cross-sectional view of an aerosol generating system comprising an electrically operated aerosol generating device and Figure 1 The aerosol-generating article shown in .

[0128] Figure 1 The aerosol-generating article 10 shown in FIG comprises a strip 12 of aerosol-generating substrate, a support element 14 provided as a hollow tubular element, a cooling element 16, and a mouth-end filter segment 18. These four elements are arranged in sequence and coaxially aligned and surrounded by a substrate wrapper 20 to form the aerosol-generating article 10. The aerosol-generating article 10 has a mouth end 22 and a distal end 24 located at the end of the article opposite the mouth end 22. Figure 1 The aerosol-generating article 10 shown in is particularly suitable for use with an electrically operated aerosol-generating device that includes a heater for heating the strip of aerosol-generating substrate.

[0129] In use, air is drawn by a user through the aerosol-generating article from the distal end 24 to the mouth end 22. The distal end 24 of the aerosol-generating article may also be described as the upstream end of the aerosol-generating article 10, while the mouth end 22 of the aerosol-generating article 10 may also be described as the downstream end of the aerosol-generating article 10. Elements of the aerosol-generating article 10 located between the mouth end 22 and the distal end 24 may be described as being upstream of the mouth end 22, or alternatively, downstream of the distal end 24.

[0130] The aerosol-generating substrate 12 is located at the extreme distal or upstream end of the aerosol-generating article 10. Figure 1 In the embodiment illustrated in , the aerosol-generating substrate 12 comprises a gathered sheet of crimped homogenised tobacco material surrounded by a wrapper. The crimped sheet of homogenised tobacco material comprises glycerol as an aerosol-forming agent.

[0131] The support element 14 is located immediately downstream of the aerosol-generating substrate 12 and is adjacent to the aerosol-generating substrate 12. Figure 1 In the embodiment shown in FIG, the support element is a hollow tube formed of a fibrous filter material. The support element 14 positions the aerosol-generating substrate 12 at the extreme distal end 24 of the aerosol-generating article 10 so that it can be penetrated by the heating element of the aerosol-generating device. In practice, the support element 14 serves to prevent the aerosol-generating substrate 16 from being forced toward the aerosol-cooling element 16 within the aerosol-generating article 10 when the heating element of the aerosol-generating device is inserted into the aerosol-generating substrate 12. The support element 14 also serves as a spacer to separate the aerosol-cooling element 16 of the aerosol-generating article 10 from the aerosol-generating substrate 12.

[0132] The aerosol-cooling element 16 is located immediately downstream of and adjacent to the support element 14. In use, volatile material released from the aerosol-generating substrate 12 passes along the aerosol-cooling element 16 towards the mouth end 22 of the aerosol-generating article 10. The volatile material may cool within the aerosol-cooling element 16 to form an aerosol that is inhaled by the user. Figure 1 In the embodiment illustrated in FIG, the aerosol-cooling element comprises a tubular element 20. A rolled and gathered sheet of polylactic acid defines a plurality of longitudinal channels extending along the length of the aerosol-cooling element 40.

[0133] The filter segment 18 is located immediately downstream of the aerosol-cooling element 16 and is adjacent to the aerosol-cooling element 16 .

[0134] exist Figure 1 In the embodiment illustrated in FIG, filter segment 18 comprises a single cylindrical filter segment of fibrous filter material formed from a plurality of PHA fibers having a denier per filament of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 m2 / g. The PHA fibers have been formed and curled by a melt spinning process. The filter segment of fibrous filter material is surrounded by a filter segment wrapper (not shown).

[0135] Furthermore, support element 14 is a hollow tubular segment containing a fibrous filter material formed from a plurality of PHA fibers having a single filament denier of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned with one another along the length of the filter segment. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 m2 / g. The PHA fibers have been formed and crimped by a melt spinning process. More specifically, the fibers contain a combination of approximately 85% by weight of a PHA polymer or copolymer and 15% by weight of a PBAT / PBS blend having a 1:1 PBAT to PBS ratio.

[0136] Figure 2 The aerosol-generating article 100 shown in FIG. 1 comprises a combustible heat source 112, a strip of aerosol-generating substrate 114, a transfer element 116, an aerosol-cooling element 118, a spacing element 120, and a mouthpiece filter segment 122. These elements are arranged in sequence and coaxially aligned and surrounded by a substrate wrapper to form the aerosol-generating article 100.

[0137] Combustible heat source 112 comprises a substantially cylindrical carbonaceous material having a length of approximately 10 mm. Combustible heat source 112 is a blind heat source. In other words, combustible heat source 112 does not include any air passages extending therethrough.

[0138] The rod of aerosol-generating substrate 114 is arranged at a proximal end of the combustible heat source 112. The aerosol-generating substrate 114 comprises a substantially cylindrical rod of tobacco material 124 surrounded by a filter segment wrapper 126.

[0139] A non-combustible, substantially air-impermeable first barrier is disposed between the proximal end of the combustible heat source 112 and the distal end of the aerosol-generating substrate 114. The first barrier comprises an aluminum foil disk. The first barrier also forms a heat-conducting member between the combustible heat source 112 and the aerosol-generating substrate 114 to conduct heat from the proximal face of the combustible heat source 112 to the distal face of the aerosol-generating substrate 114.

[0140] The heat-conducting element 130 surrounds the proximal portion of the combustible heat source 112 and the distal portion of the aerosol-forming substrate 114. The heat-conducting element 130 comprises an aluminum foil tube. The heat-conducting element 130 is in direct contact with the proximal portion of the combustible heat source 112 and the filter segment wrapper 126 of the aerosol-forming substrate 114.

[0141] The cigarette holder filter 122 comprises a single cylindrical filter segment 126 of fibrous filter material formed by a plurality of PHA fibers, wherein the plurality of PHA fibers have a single filament denier of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 square meters per gram. The PHA fibers have been formed and curled by a melt spinning process. The filter segment of fibrous filter material is surrounded by a filter segment wrapper (not shown).

[0142] The spacer element 120 is provided as a hollow tube segment according to the present invention and comprises a fibrous filter material formed from a plurality of PHA fibers having a single filament denier of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned along the length of the filter segment. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 m2 / g. The PHA fibers have been formed and crimped by a melt spinning process. More specifically, the hollow tube segment has an inner diameter of approximately 3.30 mm and an outer diameter of approximately 7.10 mm, corresponding to a wall thickness of approximately 1.90 mm.

[0143] Figure 3 The aerosol-generating article 310 shown in FIG is a combustible smoking article that includes an aerosol-generating substrate 312 and a filter 314 arranged coaxially aligned with each other. The aerosol-generating substrate 312 includes a tobacco rod surrounded by an outer wrapper (not shown). A tipping wrapper 316 surrounds both the filter 314 and an end of the aerosol-generating substrate 312 and attaches the filter 314 to the aerosol-generating substrate 312.

[0144] Filter 314 comprises a cylindrical filter segment 318 of fibrous filter material formed by PHA fibers, wherein the PHA fibers have a single-filament denier of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 square meters per gram. The PHA fibers have been formed and curled by a melt spinning process. The filter segment of the fibrous filter material is surrounded by a filter segment wrapper (not shown).

[0145] In addition, the filter 314 includes a hollow tube section 320 that is arranged to be axially aligned with and immediately downstream of the filter section 318. The hollow tube section 320 contains a fibrous filter material formed of PHA fibers having a single filament denier of approximately 3 and a total denier of approximately 27,000. The PHA fibers have a circular cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter section. The exposed surface area of ​​the PHA fibers is equivalent to approximately 0.16 square meters per gram. The PHA fibers have been formed and curled by a melt spinning process.

[0146] Figure 4 A portion of an electrically operated aerosol generating system 200 is shown, which utilizes heater blades 210 to heat Figure 1 The strip 12 of aerosol-generating substrate of the aerosol-generating article 10 is shown in FIG. The heater blade 210 is mounted within the aerosol-generating article chamber within the housing of the electrically operated aerosol-generating device 212. The aerosol-generating device 212 defines a plurality of air holes 214 to allow air to flow to the aerosol-generating article 10, as shown. Figure 4 The aerosol generating device 212 includes an Figure 4 The power supply and electronics are shown in FIG.

[0147] Comparative Example

[0148] [Incorporate discussion of Tests 1 and 2 from the IDR?]

[0149] PHA filter segments according to the present invention were prepared from PHA fibers, the parameters of which are shown in Table 1 below. The PHA fibers were formed using a melt spinning process, and the fibers were then crimped and formed into filter segments using standard filter manufacturing equipment. For comparison purposes, conventional cellulose acetate (CA) tow filter segments were prepared, which had similar denier per filament (dpf) and total denier values.

[0150] Table 1: Parameters of PHA filter segment and cellulose acetate filter segment

[0151] parameter PHA filter section CA filter segment Denier per yarn 3.2 3 Total denier 27000 27000 Filter section weight (mg) 406.76 409.76 <![CDATA[Exposed surface area (m 2 / g)]]> 0.161 0.329

[0152] In the first test, water absorption was compared between a PHA filter segment according to the present invention and a CA filter segment exposed to water. For each filter segment, the filter segment packaging was removed and the filter segment was attached to the probe of a force tensiometer (KRUSS Force Tensiometer, Model K100). The filter segment was moved downward by the probe toward a container of water and automatically stopped when the filter segment came into contact with the water. The filter segment was kept in contact with the water for 300 seconds so that the filter material could absorb the water, and then the filter segment was weighed to determine the amount of water absorbed during the test. For each of the PHA filter segment and the CA filter segment, the test was repeated three times and the average value of the water absorption was calculated, as shown in Table 2 below:

[0153] Table 2: Water uptake by PHA and CA filter segments after exposure to water

[0154]

[0155] The amount of water absorbed by the PHA filter segment according to the invention during the test was therefore less than 40% of the amount of water absorbed by the CA filter segment. This test therefore demonstrates that the water affinity of the PHA filter segment according to the invention is significantly reduced compared to a conventional CA filter segment.

[0156] In the second test, the water absorption of PHA filter segments and CA filter segments according to the present invention exposed to moisture was compared. For each filter segment, the filter segment packaging was removed, the fibers forming the filter segment were placed in a petri dish, and exposed to air at 22 degrees Celsius and 50% relative humidity for 70 hours. This was performed in a vapor sorption analyzer (ProUmid SPSx-1μ). For each filter segment, the weight of the fibers was measured at the beginning of the test, and the weight change over time due to the absorption of water vapor by the fibers was measured. For each of the PHA filter segments and the CA filter segments, the mass percentage difference (% dm) value of the sample was calculated, which represents the increase in sample weight as a percentage of the initial weight. The % dm value for each sample at the end of the 70-hour test is shown in Table 3 below:

[0157] Table 3: Water uptake by PHA and CA filter segments after exposure to moisture

[0158]

[0159]

[0160] The results demonstrate that the amount of water vapor absorbed by the cellulose acetate fibers during the 70-hour test period was more than 50 times greater than that absorbed by the PHA fibers. The PHA fibers absorbed very little water vapor during the test period. This further demonstrates that the water affinity of the PHA filter segments according to the present invention is significantly reduced compared to conventional CA filter segments.

[0161] In a third test, water absorption from mainstream smoke was compared between a PHA filter segment according to the present invention and a conventional CA filter segment. For each filter segment, a combustible tobacco rod and a single segment of filter material forming a filter were combined as described above. Figure 3 Conventional smoking articles were prepared as described.Each smoking article was then smoked in a smoking machine under ISO conditions as set out in ISO 3308:2000 (puff volume 35 ml; puff duration 2 seconds every 60 seconds) and the resulting smoke analysed.

[0162] For each filter segment, the amount of water in the mainstream smoke collected during the smoking test was measured as shown in Table 4:

[0163] Table 4: Water in mainstream smoke generated during smoking tests under ISO conditions

[0164] PHA filter section CA filter segment Water (mg / smoking article) 0.82 0.68

[0165] This demonstrates that, when smoked under equivalent conditions, the mainstream smoke produced by the smoking article incorporating the PHA filter segment has a water content approximately 20% higher than the mainstream smoke from the smoking article including the CA filter segment. This demonstrates that the PHA filter segment absorbs less water from the mainstream smoke than the CA filter segment, thereby reducing the potential problem of dry smoke as described above.

Claims

1. An aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article comprising, arranged in linear order: a first filter segment of filter material; a strip of aerosol-generating substrate, wherein the strip of aerosol-generating substrate is located immediately downstream of the first filter segment of the filter material and comprises at least 12% by weight of an aerosol-former, and wherein the strip of aerosol-generating substrate has a length of 5 mm to 50 mm; a hollow tube section having a supporting function and containing a fibrous filter material, said hollow tube section being located immediately downstream of said strip and longitudinally aligned with said strip; a second filter segment of filter material, the second filter segment of filter material being located downstream of the hollow tube segment; as well as an outer wrapper, the outer wrapper surrounding the first filter segment, the rod, the hollow tube segment, and the second filter segment; The fibrous filter material comprises at least 85% by weight of fibers containing a polyhydroxyalkanoate (PHA) polymer or copolymer, and the hollow tube segment comprises at least 25% by weight of the PHA polymer or copolymer. 2 . The aerosol-generating article according to claim 1 , wherein the fibrous filter material comprises at least 90% by weight of fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer.

3. An aerosol-generating article according to claim 1, wherein the fibrous filter material comprises at least 5% fibers comprising cellulose acetate.

4. An aerosol-generating article according to claim 3, wherein the fibrous filter material comprises at least 10% fibers comprising cellulose acetate.

5. The aerosol-generating article of claim 1 , wherein the fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer further comprise at least one biodegradable polymer selected from the group consisting of polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polyglycolide (PGA), polyvinyl alcohol (PVOH / PVA), viscose, polysaccharides, polyamides, protein-based biopolymers, and combinations thereof. 6 . The aerosol-generating article according to claim 5 , wherein the polysaccharide is starch, regenerated cellulose, cellulose acetate having a degree of substitution (DS) of less than 2.1, a chitosan-chitin based biopolymer, or a combination thereof.

7. The aerosol-generating article according to claim 6, wherein the starch is a thermoplastic starch, a thermoplastic starch blend (TPS) or a combination thereof.

8. The aerosol-generating article according to claim 5, wherein the at least one biodegradable polymer is one or more of PBAT, PCL and PBS.

9. The aerosol-generating article of claim 1 , wherein the fibrous filter material comprises at least 3% by weight of a plasticizer selected from triacetin, triethylene glycol diacetate (TEGDA), ethylene vinyl acetate, polyvinyl alcohol, starch, or a combination thereof.

10. An aerosol-generating article according to claim 1, wherein the fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer are between 3.2 denier per filament and 5 denier per filament.

11. An aerosol-generating article according to claim 1 , wherein the fibers comprising a polyhydroxyalkanoate (PHA) polymer or copolymer are curled.

12. An aerosol-generating article according to claim 1, wherein the RTD of the filter segment is less than 10 mm H20.

13. An aerosol-generating article according to claim 1, wherein the hollow tube segment has a wall thickness of at least 0.3 mm or / and a wall thickness of less than or equal to 1.5 mm.

14. The aerosol-generating article of claim 1, the hollow tube segment having a length of at least 4 mm.

15. An aerosol-generating article according to claim 1, wherein the hollow tube segment has a dry radial hardness of at least 90%.

16. A system comprising an aerosol-generating device and an aerosol-generating article according to any one of claims 1 to 15, the aerosol-generating article being for use with the aerosol-generating device, the aerosol-generating device being configured to heat, but not combust, the aerosol-generating substrate.

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