KR20220109420A - Aerosol-generating article filter with novel filtration material - Google Patents

Abstract

The aerosol-generating article 10 ( 100 ) 310 includes an aerosol-generating substrate 12 , 114 , 312 ; and a filter (18) (122) (314) axially aligned with the aerosol-generating substrate, wherein the filter (18) (122) (314) comprises a plurality of fibers comprising a polyhydroxyalkanoate compound. and at least one filter segment (126) (318) of filtration material, wherein the fibers provide a total outer surface area of between 0.12 square meters/gram and 0.28 square meters/gram. The at least one filter segment comprises at least 20% by weight of a polyhydroxyalkanoate compound.

Description

Aerosol-generating article filter with novel filtration material

The present invention relates to filters for aerosol-generating articles and to aerosol-generating articles including filters.

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 in an end-to-end relationship most commonly abutting the wrapped tobacco rod. Cylindrical filters typically include one or more plugs of fibrous filtration material, such as cellulose acetate tow, surrounded by paper plug wrap. Typically, the wrapped tobacco rod and filter are joined with a strip of tipping wrapper, which is formed of an opaque paper material that circumscribes a portion of the wrapped tobacco rod and usually the entire length of the filter. .

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, are heated without burning are also known in the art. Typically, in such articles the aerosol is generated by the transfer of heat to an aerosol-generating substrate or material that is physically separate from the heat source.

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

During use of one such aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer and are entrained in air drawn through the aerosol-generating article. As the released compound cools, the compound condenses to form an aerosol.

Typically, an aerosol-generating article of the type described may comprise a mouthpiece comprising a porous filtering material such as cellulose acetate. In some known aerosol-generating articles, a hollow tubular segment formed of a filtering material such as cellulose acetate is provided at a location between the aerosol-generating substrate and the mouth end of the article to impart structural strength to the article.

Cellulose acetate, the most commonly used filtration material, can provide relatively high filtration efficiencies and filters of cellulose acetate tow provide effective filtration of mainstream smoke generated from aerosol-generating substrates. However, cellulose acetate has also been found to provide relatively high levels of water absorption and entrapment from mainstream smoke. Thus, mainstream smoke delivered to the consumer has a significantly reduced moisture content and may be perceived as undesirably 'dry' under certain conditions. This can have an adverse effect on the overall smoking experience.

Cellulose acetate and many other commonly used filtration materials are not highly biodegradable. However, alternative dispersible or degradable materials are often unable to provide consumers with acceptable filtration efficiencies and smoking experiences. In addition, many of the known dispersible and degradable materials are unsuitable for use in existing manufacturing processes and would require very large modifications to existing methods and equipment to make their use commercially viable.

It would be desirable to provide novel and improved aerosol-generating articles having improved biodegradation properties compared to known articles comprising conventional filtration materials such as cellulose acetate. It would be particularly desirable to provide such novel aerosol-generating articles that provide the consumer with an improved smoking experience. For example, as noted above, it would be desirable to provide an aerosol-generating article capable of reducing the 'dry' smoke effect often found in articles comprising cellulose acetate as a filtration material. It would be more desirable to provide one such aerosol-generating article in which the resistance to aspiration (RTD) of a segment of filtration material can be adjusted to achieve an acceptable RTD of the article as a whole. It would also be desirable to provide such aerosol-generating articles that can be efficiently manufactured in an automated high-speed manufacturing process without requiring major modifications to existing equipment.

The present disclosure relates to an aerosol-generating article for generating an inhalable aerosol upon heating or combustion. The aerosol-generating article may include a rod of an aerosol-generating substrate and a filter segment axially aligned with the rod. The filter segment may include a filtration material formed of a plurality of fibers comprising a polyhydroxyalkanoate (PHA) compound. The fibers comprising the PHA compound may provide a total external surface area within the filter segment of from 0.12 square meters per gram to about 0.28 square meters per gram.

The present disclosure also relates to filters for aerosol-generating articles. The filter may comprise at least one filter segment of filtration material. The filter segment may include a filtration material formed of a plurality of fibers comprising a polyhydroxyalkanoate (PHA) compound. The fibers comprising the PHA compound may provide a total external surface area within the filter segment of from 0.12 square meters per gram to about 0.28 square meters per gram.

According to the present invention, there is provided an aerosol-generating article comprising an aerosol-generating substrate and a filter axially aligned with the aerosol-generating substrate, the filter comprising a plurality of fibers comprising a polyhydroxyalkanoate (PHA) compound. at least one filter segment of filtration material. The fibers comprising the polyhydroxyalkanoate compound provide a total external surface area within the filter segment of from about 0.12 square meters per gram to about 0.28 square meters per gram.

According to the present invention, there is further provided a filter comprising at least one filter segment of a filtration material comprising a plurality of fibers comprising a polyhydroxyalkanoate (PHA) compound. The fibers comprising the polyhydroxyalkanoate compound provide a total external surface area within the filter segment of from about 0.12 square meters per gram to about 0.28 square meters per gram.

The term “aerosol-generating article” is used herein with reference to 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” describes a substrate capable of releasing volatile compounds upon heating or combustion to generate an aerosol.

Conventional cigarettes ignite when a user applies a flame to one end of the cigarette and draws air through the other end. The local heat provided by the flame and the oxygen in the air drawn through the cigarette cause the tip of the cigarette to ignite, and the resulting combustion produces inhalable smoke. In contrast, in heated aerosol-generating articles, the aerosol is generated by heating a flavor-generating substrate, such as, for example, a tobacco-based substrate or a substrate containing an aerosol former and fragrance. 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 to an aerosol-generating material physically separated from a combustible fuel element or heat source.

The filter of the present invention may find application as a filter in a mouthpiece in heated aerosol-generating articles in which the aerosol-generating substrate is heated to generate an aerosol, without combustion of the substrate. However, the filters of the present invention are also suitable for use as filters in combustible smoking articles wherein the aerosol-generating substrate burns during use to generate smoke.

As used herein, the term “aerosol-generating substrate” describes a substrate that is capable of releasing volatile compounds upon heating (including combustion) that can form an aerosol. Aerosols generated from aerosol-generating substrates may be visible or invisible and include vapors (e.g., particulates of materials in the gaseous state that are normally liquid or solid at room temperature), as well as droplets of gases and condensed vapors. can do. As used herein, the term “aerosol” includes aerosols generated upon heating of a substrate in a heated aerosol-generating article and smoke generated upon combustion of a substrate within a combustible smoking article.

As defined above, the present invention provides a filter for an aerosol-generating article, wherein the filter is formed of a plurality of fibers comprising a PHA compound having a total external surface area within the filter segment of 0.12 square meters/gram to 0.28 square meters/gram. at least one filter segment comprising material. PHA-containing fibers are referred to hereinafter as “PHA fibers”. A filter segment comprising a plurality of PHA containing fibers is hereinafter referred to as a “PHA filter segment”.

PHAs are a family of polyhydroxyesters of 3, 4, 5 and 6-hydroxyalkanonic acids, which are produced by various bacterial species under nutrient limiting conditions with an excess of carbon and are found as discrete cytoplasmic inclusions in bacterial cells. PHA molecules are typically composed of 600 to 35,000 (R)-hydroxy fatty acid monomer units. Depending on the total number of carbon atoms in the PHA monomer, the PHA can be a short chain length PHA (scl-PHA; 3 to 5 carbon atoms), a medium chain length PHA (mcl-PHA; 6 to 14 carbon atoms), or a long chain length PHA ( lcl-PHA; 15 or more carbon atoms).

PHA fibers have lower hydrophilicity of equal weight compared to fibers of other filtration materials such as cellulose acetate. Thus, in the aerosol-generating article of the present invention, it has been found that the filter segment has a significantly low tendency to absorb water/vapor from the aerosol generated from the aerosol-generating substrate during use. As a result, the level of water in the aerosol can advantageously be maintained at a higher level. This directly solves the problem of "dry smoke" commonly encountered in conventional smoking articles, and provides the consumer with an improved smoking experience.

Since PHA fibers have a higher level of biodegradability compared to fibers of other filtration materials such as cellulose acetate, the article according to the invention is overall more biodegradable. At the same time, since the PHA fiber is obtained by a natural fermentation process, the aerosol-generating article according to the invention also provides improved sustainability for the production process.

Filters formed from PHA fibers have also been found to provide good filter hardness, which can be further improved by enclosing the filter segments with a rigid plug wrap.

In accordance with the present invention, the PHA filter segment is formed of PHA fibers arranged to provide a total external surface area of from 0.12 square meters per gram to 0.28 square meters per gram.

Accordingly, the total outer surface area of the PHA fibers in the PHA filter segment is at least about 0.12 square meters per gram. Preferably, the total outer surface area of the PHA fibers in the PHA filter segment is at least about 0.13 square meters/gram, more preferably at least about 0.14 square meters/gram, more preferably at least about 0.15 square meters/gram.

Further, the total outer surface area of the PHA fibers in the PHA filter segment is less than or equal to about 0.28 square meters/gram. Preferably, the total outer surface area of the PHA fibers in the PHA filter segment is about 0.27 square meters per gram or less, more preferably about 0.26 square meters per gram or less, more preferably about 0.25 square meters per gram or less.

A defined range of total external surface area has been found to provide an optimal balance between controlling and reducing the level of water absorption of a PHA filter segment while maintaining an acceptable level of resistance to aspiration (RTD) for the PHA filter segment. Accordingly, the PHA filter segments of the present invention are very versatile as they may be suitable for use in both combustible smoking articles and heated aerosol-generating articles. This allows the manufacture of filter segments for different types of aerosol-generating articles to be carried out using the same manufacturing equipment and technology, since the same filtration material is suitable for use in different things. Accordingly, the production of the filter segment can be carried out in a more efficient manner.

The level of RTD provided by the PHA filter segment may be low enough to allow the PHA filter segment to be used in heated aerosol-generating articles where relatively low RTD levels are desirable. Also, the level of RTD is low enough that, for example, in combustible smoking articles, a relatively long PHA filter segment can be provided without adversely affecting the overall RTD.

Most of the outer surface of the PHA fiber will typically be exposed within the PHA filter segment, and thus will come into contact with the aerosol generated from the aerosol-generating substrate as it passes through the PHA filter segment during use. Thus, the total external surface area of the PHA fibers affects the filtration of the aerosol as it passes through the PHA filter segment. Thus, the sensory properties of the aerosol can be controlled by varying the total external surface area of the PHA fibers.

For example, by increasing the total external surface area within a defined range, it may be possible to control the absorption and retention of certain aerosol components, such as water. This may advantageously improve the sensorial properties of the aerosol delivered from the aerosol-generating substrate to the consumer. As discussed above, the selection of the total outer surface area of the PHA fibers within the defined range allows a PHA filter segment to be provided that can reduce the level of moisture absorption by the filter segment as compared to an equivalent cellulose acetate tow segment. This can be beneficial for combustible smoking articles, where it is desirable to reduce water absorption from mainstream smoke to reduce the 'dry smoke' effect. It can also be beneficial for heated aerosol-generating articles in which the aerosol-generating substrate is heated to generate an aerosol during use. For example, when the aerosol-generating substrate is heated at a relatively low temperature, or when a high moisture content aerosol is desired, it may be advantageous to provide reduced levels of water adsorption by the PHA filter segment.

Advantageously, the level of moisture absorption provided by the PHA filter segment of the present invention enables an acceptable smoking experience to be provided for many different types of aerosol-generating articles.

The total outer surface area of the PHA fibers in the PHA filter segment may be varied within a defined range by controlling at least one of the cross-sectional size, cross-sectional shape and number of PHA fibers.

The PHA fibers may have a substantially round cross-section. In this embodiment, the total outer surface area of the PHA fibers in the filter segment is preferably from about 0.12 square meters per gram to about 0.16 square meters per gram.

The PHA fibers may have a Y-shaped cross-section. In this embodiment, the total outer surface area of the PHA fibers in the filter segment is preferably from about 0.21 square meters per gram to about 0.28 square meters per gram.

Preferably, the PHA fibers have a denier/filament (dpf) of from about 3.2 to about 5.0. The denier per filament, which corresponds to the average denier of the individual PHA fibers in the filter, is the weight in grams of a single fiber or filament having a length of 9000 m. Thus, in the present invention, the value of dpf represents the thickness of each individual PHA fiber in the filter segment. Denier per filament is expressed in denier units, where 1 denier corresponds to 1 g/9000 m. The dpf of a filter or filter segment can be readily determined based on measurements of the weight and length of a representative fiber sample from the filter or filter segment.

Accordingly, the denier per filament (dpf) of the PHA fibers is preferably at least about 3.2. Preferably, the dpf is at least about 3.3, more preferably at least about 3.4, more preferably at least about 3.5, more preferably at least about 3.6, even more preferably at least about 3.7.

The denier per filament (dpf) of the PHA fibers is preferably about 5.0 or less. Preferably, the dpf is about 4.9 or less, more preferably about 4.8 or less, more preferably about 4.7 or less, more preferably about 4.6 or less, more preferably about 4.5 or less.

In some embodiments, the denier per filament can be from about 3.3 to about 4.9, or from about 3.4 to about 4.8, or from about 3.5 to about 4.7, or from about 3.6 to about 4.6, or from about 3.7 to about 4.5.

In other embodiments, the denier per filament can be from about 3.2 to about 4.2, or from about 3.2 to about 4.0, or from about 3.2 to about 3.8, or from about 3.2 to about 3.6, or about 3.4.

In other embodiments, the denier per filament can be from about 4.0 to about 5.0, or from about 4.2 to about 5.0, or from about 4.4 to about 5.0.

Preferably, the total denier of the filtration material comprising PHA fibers is from about 20,000 to about 50,000, more preferably from about 25,000 to about 40,000, more preferably from about 30,000 to about 40,000. The “total denier” of a filtration material is defined as the total weight in grams of 9000 m of combined fibers forming the filtration material. Thus, the total denier for a filter segment corresponds to the denier per filament multiplied by the total number of fibers in the filter segment.

The PHA fibers provided in the filter of the aerosol-generating article according to the present invention may be formed of any suitable PHA compound, including a PHA polymer or copolymer. Suitable PHA compounds include, but are not limited to, polyhydroxypropionic acid, polyhydroxyvalerate, polyhydroxybutyrate, polyhydroxyhexanoate and polyhydroxyoctanoate. In a particularly preferred embodiment, the PHA compound is poly(3-hydroxybutyrate).

The PHA filter segment preferably comprises at least about 5 wt% PHA fibers, more preferably at least about 10 wt% PHA fibers, more preferably at least about 20 wt% PHA fibers, more preferably at least at least about 30% by weight PHA fibers, more preferably at least about 40% by weight PHA fibers, more preferably at least about 50% by weight PHA fibers, more preferably at least about 60% by weight PHA fibers, more preferably comprises at least about 70 wt% PHA fibers, more preferably at least about 80 wt% PHA fibers, more preferably at least about 90 wt% PHA fibers, more preferably at least about 95 wt% PHA fibers do.

The remainder of the fibers in the PHA filter segment may comprise any suitable material. Suitable fibrous materials will be known to those skilled in the art and include, but are not limited to, polylactic acid (PLA) and cellulose acetate.

Thus, the PHA filter segment is formed with a relatively high level of PHA fibers. This provides for improved biodegradability of the filter and the aerosol-generating article as a whole. As noted above, it has previously been found to be technically difficult to form filter segments with high proportions of degradable polymers that provide acceptable filtration properties. However, the present inventors have surprisingly found that it is possible to produce filter segments comprising relatively high levels of PHA fibers that provide desirable levels of filtration properties such as filtration efficiency and resistance to suction.

The PHA fibers of filters according to the present invention may be prepared using any suitable method. Suitable techniques for making PHA fibers will be known to those skilled in the art and include, but are not limited to, melt spinning, gel spinning and electrospinning. Preferably, the PHA fibers are produced by melt spinning. Melt spinning is often considered the most economical spinning process because, conversely, as is the case with solution spinning, there is no need to recover or evaporate the solvent. In addition, the spinning speed by melt spinning is generally quite high, which is advantageous in terms of overall productivity and manufacturing efficiency.

PHA fibers can be optionally crimped in the same way as cellulose acetate fibers in conventional filter segments.

The PHA filter segment may be formed of a fibrous filtration material formed exclusively of PHA fibers. However, in certain preferred embodiments of the present invention, the PHA fibers may be combined with a plurality of fibers of additional biodegradable polymers to form filter segments. For example, the filter segment is preferably made of starch, polybutylene succinate (PBS), polybutyrate adipate terephthalate (PBAT), thermoplastic starch and thermoplastic starch blend (TPS), polycaprolactone (PCL), poly Glycolide (PGA), polyvinyl alcohol (PVOH/PVA), viscose, regenerated cellulose, polysaccharide, cellulose acetate with a degree of substitution (DS) less than 2.1, polyamide, protein-based biopolymer, chitosan-chitin-based biopolymer , and at least about 5 weight percent of at least one biodegradable polymer selected from the group consisting of combinations thereof. The inventors have discovered that the inclusion of one or more of these components in the blend from which the fibrous material of the filter segment is formed further contributes to improving the biodegradability of the filter segment and the aerosol-generating article as a whole.

In a preferred embodiment, the PHA filter segment comprises at least about 10% by weight of this additional biodegradable polymer. More preferably, the PHA filter segment comprises at least about 11 wt% or at least 12 wt% or at least 13 wt% or at least 14 wt% of the additional biodegradable polymer. Even more preferably, the PHA filter segment comprises at least about 15% by weight of one such additional biodegradable polymer.

The inventors have discovered that the inclusion of one or more of these components in the blend from which the fibrous material of the filter segment is formed further contributes to improving the biodegradability of the filter segment and the aerosol-generating article as a whole.

In addition, while it has previously been found to be technically difficult to produce filaments or fibers containing PHA using existing techniques and equipment, the inventors have surprisingly found that when PHA is combined into a blend as described above, high levels of PHA are produced. It has been found that it is possible to produce filaments or fibers comprising

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

PHA fibers may be formed solely of the PHA compound or in combination with one or more other polymers such as polylactic acid (PLA). Thus, PHA fibers are formed from a blend of polymers comprising a PHA compound.

The PHA filter segment preferably comprises at least about 5% by weight of a PHA compound, more preferably at least about 10% by weight of a PHA compound, more preferably at least about 20% by weight of a PHA compound, more preferably, At least about 30% by weight of a PHA compound, more preferably at least about 40% by weight of a PHA compound, more preferably at least about 50% by weight of a PHA compound, more preferably at least about 60% by weight of a PHA compound , more preferably at least about 70% by weight of PHA compound, more preferably at least about 80% by weight of PHA compound, more preferably at least about 90% by weight of PHA compound, more preferably at least about 95% by weight of PHA compound. % by weight of the PHA compound.

The PHA filter segment of the aerosol-generating article according to the invention preferably further comprises an additive for reducing certain smoke components in the aerosol generated from the aerosol-generating substrate. For example, the PHA filter segment preferably further comprises an additive for the reduction of phenol and phenol derivatives. Suitable additives will be known to those skilled in the art and include, but are not limited to, polyethylene glycol (PEG), triacetin, triethyl citrate, cellulose acetate flakes, or combinations thereof.

Preferably, the filter segment comprises from about 3% to about 15% by weight additive, more preferably from about 5% to about 9% by weight additive.

In certain preferred embodiments of the present invention, the PHA filter segment comprises polyethylene glycol such as PEG 400. The combination of PHA fibers with additives such as PEG for the reduction of phenolic compounds from aerosols generated from aerosol-generating substrates has 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 including compounds that specifically reduce the level of phenolic compounds in the aerosol generated from the aerosol-generating substrate, it is possible to further optimize the filtration capacity of the filter according to the invention comprising PHA fibers. This in turn improves the sensory characteristic of the aerosol delivered to the consumer.

In a particularly preferred embodiment, the PHA filter segment further comprises at least about 5 weight percent polyethylene glycol, based on the total weight of the filtration material. Preferably, the filter segment comprises no more than 10% by weight of polyethylene glycol, based on the total weight of the filtration material.

In another preferred embodiment of the present invention, the PHA filter segment further comprises a mixture of cellulose acetate and triacetin. Preferably, the mixture comprises at least 90% by weight of triacetin and at most 10% by weight of cellulose acetate. The mixture can be formed by adding cellulose acetate flakes to triacetin to form a solution. The solution can then be sprayed onto the PHA fibers in the PHA filter segment. This combination has been found to advantageously replicate the combined effect of triacetin and cellulose acetate fibers in filters of conventional cigarettes.

As noted above, PHA fibers have been found to absorb less water from aerosols generated from aerosol-generating substrates than equivalent amounts of cellulose acetate fibers, due to the lower affinity of PHA fibers for water. As demonstrated in the examples below, the amount of water absorbed by the PHA filter segment is significantly lower than the amount of water absorbed by the comparative filter segment formed of an equivalent weight of cellulose acetate fibers.

For example, when exposed to water in liquid form, it is preferred that the PHA filter segments of the present invention absorb less than half the amount of water absorbed under the same conditions by an equivalent filter segment formed of cellulose acetate fibers.

Compared to cellulose acetate, the reduced water uptake by the PHA fibers in the filters of the present invention results in higher levels of water in the aerosol delivered from the aerosol-generating article during use.

For example, the amount of water in the aerosol collected during smoking of a combustible smoking article comprising a filter according to the invention with PHA fibers under ISO conditions is collected during smoking of an equivalent combustible smoking article having a filter segment of cellulose acetate tow under the same conditions. It is at least 10% higher and preferably at least 15% higher than the amount of water in the aerosol.

Thus, an aerosol-generating article comprising a filter comprising a PHA filter segment can deliver an aerosol with a higher moisture level, which is more sensory acceptable to the consumer. In particular, the 'dry smoke' effect that may be experienced during smoking of an aerosol-generating article having a conventional cellulose acetate filter can be advantageously reduced.

The PHA filter segment of the aerosol-generating article according to the present invention can advantageously be adjusted to provide a desired level of resistance to aspiration (RTD). For some aerosol-generating articles, such as heated aerosol-generating articles having an aerosol-generating substrate that is heated rather than combusted to produce an aerosol, it may be desirable to provide a relatively low RTD for the PHA filter segment. This may be the case where it is desirable to provide low filtration efficiency. Alternatively, a low RTD may be desirable, for example when the aerosol-generating substrate is relatively short, or when a relatively long filter or mouthpiece is desired. For example, by using a PHA fiber having a dpf value within the upper part of a defined range with a relatively large size, a low RTD can be achieved.

For alternative aerosol-generating articles, such as combustible articles, it may be more desirable to provide a higher RTD for the PHA filter segment to increase filtration efficiency.

Preferably, in an aerosol-generating article according to the present invention, the RTD of the PHA filter segment for a 27 mm filter segment is at least about 30 mm H ₂ O. More preferably, the RTD of the PHA filter segment for a 27 mm filter segment is at least about 35 mm H ₂ O, more preferably at least about 40 mm H ₂ O. Even more preferably, in the aerosol-generating article according to the present invention, the RTD of the PHA filter segment for the 27 mm filter segment is at least about 45 mm H ₂ O, more preferably at least about 50 mm H ₂ O. The RTD of a PHA filter segment for a 27 mm filter segment is preferably about 150 mm H ₂ O or less, more preferably 125 mm H ₂ O or less, more preferably about 100 mm H ₂ O or less. For example, the RTD of a PHA filter segment for a 27 mm filter segment is from about 30 mm H ₂ O to about 150 mm H ₂ O, or from about 35 mm H ₂ O to about 150 mm H ₂ O, or about 40 mm H ₂ 0 to about 125 mm H ₂ O, or about 45 mm H ₂ O to about 100 mm H ₂ O, or about 50 mm H ₂ O to about 100 mm H ₂ O.

In certain preferred embodiments of the present invention, the PHA filter segment has an RTD (based on the length of the PHA filter segment in the article) of at least about 60 mm H ₂ O. More preferably, the RTD of the PHA filter segment is at least about 65 mm H ₂ O, more preferably at least about 70 mm H ₂ O. Even more preferably, in an aerosol-generating article according to the present invention, the RTD of the PHA filter segment is at least about 75 mm H ₂ O, more preferably at least about 80 mm H ₂ O. The RTD of the PHA filter segment (based on the length of the PHA filter segment in the article) is preferably about 120 mm H ₂ O or less, more preferably about 110 mm H ₂ O or less, more preferably about 100 mm H 2 O or less. ₂ O or less. For example, the RTD of a PHA filter segment is from about 60 mm H ₂ O to about 120 mm H ₂ O, or from about 65 mm H ₂ O to about 120 mm H ₂ O, or from about 70 mm H ₂ O to about 110 mm H ₂ O, or about 75 mm H ₂ O to about 110 mm H ₂ O, or about 80 mm H ₂ O to about 100 mm H ₂ O, or about 90 mm H ₂ O. Such ranges may be particularly suitable for combustible smoking articles.

In another preferred embodiment of the present invention, the PHA filter segment has an RTD (based on the length of the PHA filter segment in the article) of at least about 10 mm H ₂ O. More preferably, the RTD of the PHA filter segment is at least about 12 mm H ₂ O, more preferably at least about 15 mm H ₂ O. Even more preferably, in an aerosol-generating article according to the present invention, the RTD of the PHA filter segment is at least about 18 mm H ₂ O, more preferably at least about 20 mm H ₂ O. The RTD of the PHA filter segment (based on the length of the PHA filter segment in the article) is preferably about 40 mm H ₂ O or less, more preferably about 35 mm H ₂ O or less, more preferably about 30 mm H 2 O or less. ₂ O or less. For example, the RTD of a PHA filter segment is from about 10 mm H ₂ O to about 40 mm H ₂ O, or from about 12 mm H ₂ O to about 40 mm H ₂ O, or from about 15 mm H ₂ O to about 35 mm H ₂ O, or about 20 mm H ₂ O to about 30 mm H ₂ O, or about 27 mm H ₂ O. This range may be particularly suitable for heated aerosol-generating articles in which the aerosol-generating substrate is heated rather than combusted to generate an aerosol.

"Aspiration resistance" refers to the static pressure difference between the two ends of a sample when traversed by an air flow under normal conditions where the volumetric flow is 17.5 ml per second at the discharge end. The RTD of a sample can be measured using the method specified in ISO standard 6565:2002.

The PHA filter segment of the aerosol-generating article according to the invention has further been found to provide good stability in the RTD, meaning that high variability in the RTD can be advantageously avoided. For example, within 20 samples of an aerosol-generating article according to the present invention, there will typically be a standard deviation from the target RTD of between 2% and 10%, more preferably between 2% and 5%.

Preferably, the PHA filter segment of the aerosol-generating article according to the invention has an average radial hardness of at least 80%, more preferably at least 85%. Thus, the PHA filter segment can provide a desirable level of filter hardness comparable to that provided by conventional cellulose acetate tow filters. If desired, the radial hardness of the PHA filter segment can be determined by means of a rigid plug wrap, for example a plug wrap having a basis weight of at least about 80 g/m2 (gsm), or at least about 100 gsm, or at least about 110 gsm. may be further increased by surrounding

As used herein, the term “radial hardness” refers to resistance to compression in a direction transverse to a longitudinal axis. The radial hardness of the aerosol-generating article around the filter can be determined by applying a load across the article at the location of the filter transverse to the longitudinal axis of the article and measuring the average (usually) recessed diameter of the article. Radial hardness is given by:

D _S is the original (not recessed) diameter, and D _d is the recessed diameter after applying a set load for a set time. The harder the material, the closer the hardness is to 100%.

In order to measure the hardness of a portion of an aerosol-generating article (eg, a filter), the aerosol-generating article must be aligned parallel to one plane, and the same portion of each aerosol-generating article to be tested must be subjected to a set load for a set time. This test is performed using a known DD60A density meter device (manufactured by Heinr. Borgwaldt GmbH, Germany and commercially available) fitted with a measuring head for an aerosol-generating article such as a cigarette and an aerosol-generating article receptacle.

The load is applied using two load-applying cylindrical rods extending across the diameter of all aerosol-generating articles at once. In accordance with standard test methods for such devices, the test should be conducted such that 20 points of contact occur between the aerosol-generating article and the load-applying cylindrical rod. In some cases, the filter to be tested may be of sufficient length to form 20 points of contact with only 10 aerosol-generating articles (extending between rods), with each smoking article in contact with two load-applying rods. because it has sufficient length for ). In other cases, if the filter is too short to achieve this, then each aerosol-generating article should be used such that each aerosol-generating article only contacts one of the load-applying rods so that 20 aerosol-generating articles form 20 points of contact, as discussed further below. do.

Two additional stationary cylindrical rods are positioned below the aerosol-generating article to support the aerosol-generating article and to counteract the load applied by each load-applying cylindrical rod.

For the standard operating procedure of this device, a full load of 2 kg is applied for a time of 20 s. After 20 seconds (with the load still applied to the smoking article), the thickness pressed against the load-applying cylindrical rod is measured and used to calculate the hardness from the above equation. The temperature is maintained within the range of 22°C±2°C. The test described above is referred to as the DD60A test. A standard method for measuring filter hardness is when the aerosol-generating article is not consumed. Additional information regarding the determination of mean radial hardness can be found, for example, in US Patent Application Publication No. 2016/0128378.

As mentioned above, the use of PHA fibers for making filter segments of aerosol-generating articles according to the present invention advantageously provides improved biodegradability compared to conventional cellulose acetate filters.

Preferably, the PHA filter segment is at least about about It has a biodegradability in an aqueous medium of 45%, more preferably at least about 50%, and most preferably at least about 55%.

Under the same test conditions, the cellulose acetate filter segment exhibits about 30% biodegradability. Therefore, it can be seen that forming filter segments using PHA fibers instead of cellulose acetate fibers provides a significant improvement in the biodegradability of the filter segments.

The size of a PHA filter segment may vary depending on the type of aerosol-generating article in which it is included.

Preferably, the PHA filter segment has a length of at least about 4 mm, more preferably at least about 5 mm, more preferably at least about 7 mm, and most preferably at least about 10 mm.

Preferably, the PHA filter segment has a length of about 30 mm or less, about 27 mm or less in length, more preferably about 25 mm or less in length, and most preferably about 20 mm or less in length.

For example, the length of the PHA filter segment is 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, most preferably from about 20 mm. to about 30 mm. Alternatively, the length of the PHA filter segment in this embodiment 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, most preferably from about 20 mm to about 27 mm. As a further alternative, in this embodiment, the length of the PHA 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, more more preferably from about 15 mm to about 30 mm, and most preferably from about 20 mm to about 25 mm.

For embodiments of the invention in which the aerosol-generating article is in the form of a combustible smoking article, the length of the PHA filter segment is preferably from about 20 mm to about 30 mm, more preferably from about 25 mm, as will be described in more detail below. to about 30 mm, most preferably about 27 mm.

As an alternative embodiment of the present invention, in the case of an alternative embodiment of the present invention wherein the aerosol-generating article is in the form of a heated aerosol-generating article having an aerosol-generating substrate which is intended to be heated by an electric heating means or an integral heat source, in more detail below As will be explained, the length of the PHA filter segment is preferably from about 5 mm to about 15 mm, more preferably from about 5 mm to about 10 mm, and most preferably from about 7 mm.

The PHA filter segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The filter segment preferably has an outer diameter of at least 5 mm. The PHA 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 PHA filter segment has an outer diameter of 7.2 mm+/-10%.

The shape of the PHA filter segment may also be altered depending on the desired configuration of the aerosol-generating article. In certain embodiments, the PHA filter segment may be in the form of a solid cylindrical plug of fibrous filtration material comprising PHA fibers. Thus, this filter segment would provide a construction similar to a conventional plug of cellulose acetate tow.

In an alternative embodiment, the PHA filter segment may be in the form of a hollow tube segment. The hollow tube segment has a larger exposed surface area than an equivalent diameter cylindrical plug, which can further improve the biodegradation of the PHA filter segment.

Preferably, the wall thickness of the hollow tube segment is at least about 0.3 mm. More preferably, the wall thickness of the hollow tube segment is at least about 0.4 mm. Even more preferably, the wall thickness of the hollow tube segment is at least about 0.5 mm.

Preferably, the wall thickness of the hollow tube segment is about 1.9 mm or less. More preferably, the wall thickness of the hollow tube segment is about 1.5 mm or less. Even more preferably, the wall thickness of the hollow tube segment is about 1.2 mm or less. Particularly preferably, the hollow tube segment has a wall thickness of about 0.9 mm or less.

In some embodiments, the hollow tube segment can typically have a length of at least about 4 mm. More preferably, the length of the hollow tube segment is at least about 5 mm. More preferably, the length of the hollow tube segment is at least about 7 mm. Even more preferably, the length of the hollow tube segment is at least about 10 mm.

When the PHA filter segment is in the form of a hollow tube segment, the filtration material may comprise some cellulose acetate in addition to the PHA fibers. For example, the hollow tube segment may comprise from about 5 weight percent to about 15 weight percent cellulose acetate. Without wishing to be bound by theory, it will be understood that a certain amount of cellulose acetate in the hollow tube segment may facilitate the manufacture of the hollow tube segment as well as impart desirable filtration and mechanical properties to the hollow tube segment.

The filter of the aerosol-generating article according to the invention may be a single segment filter consisting solely of PHA filter segments. Alternatively, the filter of the aerosol-generating article according to the present invention may further comprise one or more additional filter segments formed of a filtering material, which may be provided upstream or downstream of the PHA filter segment as described above. For example, a PHA filter segment may be combined with one or more axially aligned filter plugs formed of a fibrous filtration material that may or may not include PHA fibers. Alternatively or additionally, the PHA filter segment may be combined with one or more tubular elements, such as hollow acetate tubes or cardboard tubes. For example, in certain embodiments the filter may include a support element in the form of a hollow acetate tube. Alternatively or additionally, the PHA filter segment may be combined with an aerosol cooling element.

Preferably, the further filter segment is formed of a material other than cellulose acetate. Particularly preferably, the further filter segment comprises PHA fibers, which can optionally be held in the desired shape by means of a suitable adhesive such as PVA. Preferably, each additional filter segment comprises at least about 25% by weight of a PHA compound, more preferably at least about 50% by weight of a PHA compound.

The filter of the aerosol-generating article according to the invention may optionally comprise a flavoring agent. Flavoring agents may be incorporated using a variety of different means known to those skilled in the art. For example, the flavoring agent may be incorporated in the form of a capsule that may be provided to the PHA filter segment or additional filter segments.

Preferably, the filter of the aerosol-generating article according to the present invention comprises a capsule within a PHA filter segment, wherein the capsule contains additives for modifying the aerosol generated from the aerosol-generating substrate during use. Preferably, the additive is a flavoring agent. The use of PHA fibers having a dpf value in the range of 3.2 to 5.0 means that the PHA fibers can have a relatively large cross-section. This in turn means that the amount of space available between individual fibers is increased compared to filters formed from fibers with low dpf values. Accordingly, PHA filter segments formed from PHA fibers having a dpf within this range are particularly suitable for incorporation of capsules. Capsules can be readily incorporated into the PHA filter segment during manufacture. In addition, the capsule will effectively remain in the desired axial position within the PHA filter segment.

The filter of the aerosol-generating article according to the invention is preferably in an outer wrapper, for example a tipping wrapper surrounding the filter segment, the downstream end of the aerosol-generating substrate, and any further components that may be provided therebetween. surrounded by The tipping wrapper may comprise a removable tipping wrapper portion, as described in WO-A-2017/162838. This allows at least a portion of the tipping wrapper to be removed before the aerosol-generating article is disposed of. Removal of the tipping wrapper exposes the underlying filter segment, which can advantageously speed up the biodegradation of the filter material.

As defined above, the aerosol-generating article according to the invention further comprises an aerosol-generating substrate, preferably in the form of a rod of the aerosol-generating substrate. Preferably, the aerosol-generating substrate is a rod of tobacco material.

The aerosol-generating substrate may have a length of from about 5 mm to about 100 mm. Preferably, the aerosol-generating substrate has a length of at least about 5 mm, more preferably at least about 7 mm. Additionally or alternatively, the 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 aerosol-generating substrate has a length of less than about 35 mm, more preferably less than about 25 mm, even more preferably less than about 20 mm. In one embodiment, the aerosol-generating substrate may have a length of about 10 mm. In a preferred embodiment, the aerosol-generating substrate has a length of about 12 mm.

In certain embodiments, an aerosol-generating article according to the present invention is a filter cigarette or other combustible smoking article comprising tobacco material in which the aerosol-generating substrate is combusted to form smoke. In any such embodiment, the aerosol-generating substrate may comprise a tobacco rod. The tobacco rod may include one or more of cut filler and reconstituted tobacco.

For embodiments in which the aerosol-generating article is in the form of a combustible smoking article, the aerosol-generating substrate, which is typically a tobacco rod, preferably has a length of from about 10 mm to about 100 mm, more preferably a total length of from about 30 mm to about 70 mm. has The tobacco rod may include one or more of cut filler and reconstituted tobacco.

As discussed above, filters of the present invention comprising PHA segments also find application in heated aerosol-generating articles in which the tobacco material is heated rather than combusted to form an aerosol. In one type of heated aerosol-generating article, the tobacco material is heated by one or more electrical heating elements to generate the aerosol. In another type of heated aerosol-generating article, the aerosol is generated by heat transfer from a combustible or chemical heat source to a physically separate tobacco material that may be located within, around, or downstream of the heat source. The present invention further includes aerosol-generating articles wherein the nicotine-containing aerosol is generated from tobacco material, tobacco extract or other sources of nicotine without combustion, in some cases without heating, for example through a chemical reaction.

In embodiments where the aerosol-generating article is in the form of a heated aerosol-generating article wherein the aerosol-generating substrate is intended to be heated to form an aerosol, the aerosol-generating substrate is preferably from about 5 mm to about 40 mm, more preferably from about 9 mm to about 15 mm in length.

For such embodiments in which the aerosol-generating article is in the form of a heated aerosol-generating article, the aerosol-generating substrate is preferably formed of a homogenized tobacco material formed from agglomeration of tobacco particles. The aerosol-generating substrate may comprise one or more corrugated sheets of homogenised tobacco material. One or more sheets may be textured. As used herein, the term 'textured sheet' refers to a sheet that has been crimped, embossed, engraved, perforated or otherwise deformed. Preferably, the aerosol-generating substrate may comprise a plurality of strips or strands of homogenised tobacco material. The strips or strands may be substantially aligned with one another in the longitudinal direction, or may be randomly oriented.

Homogenised tobacco material for use in an aerosol-generating substrate is at least about 40% by weight on a dry weight basis, more preferably at least about 60% by weight on a dry weight basis, more preferably or at least about 70% by weight on a dry basis, and Most preferably, it may have a tobacco content of at least about 90% by weight on a dry weight basis.

Homogenized tobacco material for use in an aerosol-generating substrate may include one or more intrinsic binders that are tobacco endogenous binders, one or more extrinsic binders that are tobacco exogenous binders, or a combination thereof to help agglomerate particulate tobacco. Alternatively, or additionally, homogenized tobacco material for use in an aerosol-generating substrate may contain tobacco and non-tobacco fibers, aerosol formers, wetting agents, plasticizers, flavoring agents, fillers, aqueous and non-aqueous solvents, and combinations thereof. Other additives may include, but are not limited to.

Suitable extrinsic binders for inclusion in homogenized tobacco materials for use in aerosol-generating substrates are known in the art and include 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, conjugated base salts of organic acids such as sodium alginate, agar and pectin; and combinations thereof.

Suitable non-tobacco fibers for inclusion in homogenized tobacco materials for use in aerosol-generating substrates are known in the art and include cellulosic fibers; softwood fibers; hardwood fibers; jute fibers; and combinations thereof. Prior to incorporation into homogenized tobacco material for use in an aerosol-generating substrate, the non-tobacco fibers may be subjected to mechanical pulping; refining; chemical pulping; bleaching; sulfate pulping; and combinations thereof.

Aerosol-generating substrates for heated aerosol-generating articles typically contain an aerosol former, i.e., a compound or mixture of compounds that, in use, facilitates the formation of an aerosol and is preferably substantially resistant to thermal degradation at the operating temperature of the aerosol-generating article. include Examples of suitable aerosol formers include polyhydric alcohols such as propylene glycol, triethylene glycol, 1,3-butanediol and glycerin; esters of polyhydric alcohols such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol formers are polyhydric alcohols such as propylene glycol, triethylene glycol, 1,3-butanediol or mixtures thereof, most preferably glycerin.

Preferably, the aerosol-generating substrate comprises at least 10% by weight of aerosol former, more preferably at least 12% by weight of aerosol former, more preferably at least about 15% by weight of aerosol former. Alternatively or additionally, the aerosol-generating substrate preferably contains up to 30% by weight of aerosol former, more preferably up to about 25% by weight of aerosol former, more preferably up to about 20% by weight of aerosol former include For example, the aerosol-generating substrate may comprise from about 10% to about 30% by weight of an aerosol former, or from about 12% to about 25% by weight of an aerosol former, or from about 15% to about 20% by weight of an aerosol-forming agent. agent may be included. In a particularly preferred embodiment, the aerosol-generating substrate comprises about 18% by weight of the aerosol former.

The aerosol-generating article according to the invention may further comprise one or more additional components between the filter and the aerosol-generating substrate. For example, the aerosol-generating article may further comprise one or more of a support element, an aerosol cooling element, and a delivery element. The construction of such components will be known to those skilled in the art.

For example, in certain preferred embodiments of the present invention, the aerosol-generating article is in a linear sequential arrangement: an aerosol-generating substrate, a support element immediately downstream of the aerosol-generating substrate, an aerosol cooling element positioned immediately downstream of the support element, and a mouthpiece comprising a PHA filter segment at the downstream end of the filter.

In another preferred embodiment of the invention, the aerosol-generating article comprises in a linear sequential arrangement: an aerosol-generating substrate, a delivery element, an aerosol cooling element, a spacer element and a mouthpiece filter.

In certain preferred embodiments of the present invention, the aerosol-generating article further comprises a combustible heat source at the upstream end of the aerosol-generating article, in contact with the upstream end of the aerosol-generating substrate. For example, an aerosol-generating article may include a carbonaceous heat source at its upstream end to heat the aerosol-generating substrate to generate an aerosol during use. Suitable carbonaceous heat sources will be known to those skilled in the art.

The invention will now be further described with reference to the drawings:
1 shows a schematic longitudinal sectional view of an aerosol-generating article according to a first embodiment of the invention for use with an aerosol-generating device comprising a heater element;
2 shows a schematic longitudinal sectional view of an aerosol-generating article according to a second embodiment of the invention, comprising an integral heat source;
3 shows a schematic longitudinal cross-sectional view of an aerosol-generating article according to a third embodiment of the invention;
4 shows a schematic longitudinal cross-sectional view of an aerosol-generating system comprising an electrically actuated aerosol-generating device and the aerosol-generating article shown in FIG. 1 ;

The aerosol-generating article 10 shown in FIG. 1 includes a rod of an aerosol-generating substrate 12 , a support element provided as a hollow tubular element 14 , a cooling element 16 and a mouth end filter segment 18 . These four elements are arranged sequentially and in coaxial alignment and surrounded by the 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 positioned at an opposite end of the article relative to the mouth end 22 . The aerosol-generating article 10 shown in FIG. 1 is particularly suitable for use with an electrically operated aerosol-generating device comprising a heater for heating a rod of an aerosol-generating substrate.

In use, air is drawn from the distal end 24 to the mouth end 22 through the aerosol-generating article by the user. The distal end 24 of the aerosol-generating article may also be described as an upstream end of the aerosol-generating article 10 , wherein the mouth end 22 of the aerosol-generating article 10 is also downstream of the aerosol-generating article 10 . It can be described as an end. An element of the aerosol-generating article 10 positioned between the mouth end 22 and the distal end 24 may be described as upstream of the mouth end 22 , or alternatively downstream of the distal end 24 .

The aerosol-generating substrate 12 is located at the extreme distal or upstream end of the aerosol-generating article 10 . In the embodiment illustrated in FIG. 1 , the aerosol-generating substrate 12 comprises a corrugated sheet of crimped homogenised tobacco material surrounded by a wrapper. The crimped sheet of homogenised tobacco material comprises glycerin as an aerosol former.

A support element 14 is positioned immediately downstream of the aerosol-generating substrate 12 and abuts the aerosol-generating substrate 12 . 1 , the support element is a hollow tube formed of a fibrous filtration 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 effect, the support element 14 moves the aerosol-generating substrate 16 downstream 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 . It works to prevent coercion. The support element 14 also acts as a spacer to space the aerosol cooling element 16 of the aerosol-generating article 10 from the aerosol-generating substrate 12 .

The aerosol cooling element 16 is located immediately downstream of the support element 14 and abuts the support element 16 . In use, volatiles released from the aerosol-generating substrate 12 pass 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. In the embodiment illustrated in FIG. 1 , the aerosol cooling element comprises a tubular element 20 . The crimped and corrugated sheet of polylactic acid defines a plurality of longitudinal channels extending along the length of the aerosol cooling element 40 .

The filter segment 18 is located immediately downstream of the aerosol cooling element 16 and abuts the aerosol cooling element 16 . In the embodiment illustrated in FIG. 1 , filter segment 18 comprises a single cylindrical plug of fibrous filtration material formed from a plurality of PHA fibers having a denier/filament of approximately 3.4 and a total denier of approximately 34,000. The PHA fibers have a round cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The total outer surface area of PHA fibers corresponds to about 0.16 square meters per gram. The PHA fibers were formed and crimped by a melt spinning process. A plug of fibrous filtration material is surrounded by a plug wrap (not shown).

The aerosol-generating article 100 shown in FIG. 2 includes a combustible heat source 112 , a rod of an aerosol-generating substrate 114 , a transfer element 116 , an aerosol cooling element 118 , a spacer element 120 and a mouthpiece filter segment. (122). These elements are arranged sequentially and in coaxial alignment and surrounded by a substrate wrapper to form the aerosol-generating article 100 .

The combustible heat source 112 has a length of about 10 mm and includes a substantially cylindrical body made of carbonaceous material. The combustible heat source 112 is a blind heat source. That is, combustible heat source 112 does not include any air channels extending therethrough.

A rod of the aerosol-generating substrate 114 is arranged at the proximal end of the combustible heat source 112 . The aerosol-generating substrate 114 comprises a substantially cylindrical plug of tobacco material 124 surrounded by a filter plug wrap 126 .

A non-combustible, substantially air impermeable first barrier 128 is arranged between the proximal end of the combustible heat source 112 and the distal end of the aerosol-generating substrate 114 . The first barrier 128 comprises a disk of aluminum foil. The first barrier 128 is also a heat conducting member for conducting heat between the combustible heat source 112 and the aerosol-generating substrate 114 from the proximal side of the combustible heat source 112 to the distal side of the aerosol-generating substrate 114 . to form

The heat-conducting element 130 surrounds a proximal portion of the combustible heat source 112 and a distal portion of the aerosol-forming substrate 114 . The heat-conducting element 130 comprises a tube of aluminum foil. The heat-conducting element 130 is in direct contact with the proximal portion of the combustible heat source 112 and the filter plug wrap 126 of the aerosol-generating substrate 114 .

The mouthpiece filter 122 includes a single cylindrical plug 126 of fibrous filtration material formed from a plurality of PHA fibers having a denier per filament of approximately 3.4 and a total denier of approximately 34,000. The PHA fibers have a round cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The exposed surface area of PHA fibers corresponds to about 0.16 square meters per gram. The PHA fibers were formed and crimped by a melt spinning process. A plug of fibrous filtration material is surrounded by a plug wrap (not shown).

The aerosol-generating article 310 shown in FIG. 3 is a combustible smoking article comprising an aerosol-generating substrate 312 and a filter 314 arranged in coaxial alignment with each other. The aerosol-generating substrate 312 comprises a tobacco rod surrounded by an outer wrapper (not shown). A tipping wrapper 316 surrounds both the filter 314 and the distal end of the aerosol-generating substrate 312 and attaches the filter 314 to the aerosol-generating substrate 312 .

Filter 314 includes a single cylindrical plug 318 of fibrous filtration material formed of PHA fibers having a denier per filament of approximately 3.4 and a total denier of approximately 34,000. The PHA fibers have a round cross-sectional shape and are substantially longitudinally aligned with each other along the length of the filter segment. The total outer surface area of PHA fibers corresponds to about 0.16 square meters per gram. The PHA fibers were formed and crimped by a melt spinning process. A plug of fibrous filtration material is surrounded by a plug wrap (not shown).

FIG. 4 shows a portion of an electrically operated aerosol-generating system 200 that utilizes a heater blade 210 to heat a rod of an aerosol-generating substrate 12 of the aerosol-generating article 10 shown in FIG. 1 . The heater blade 210 is mounted in an aerosol-generating article chamber inside the housing of the electrically operated aerosol-generating device 212 . The aerosol-generating device 212 defines a plurality of air apertures 214 for allowing air to flow into the aerosol-generating article 10 , as illustrated by the arrows in FIG. 4 . The aerosol-generating device 212 includes a power supply and electronics, not shown in FIG. 4 .

comparative example

The PHA filter segment according to the present invention is made from PHA fibers, the parameters of which are shown in Table 1 below. The PHA fibers are formed using a melt spinning process, then the fibers are crimped and formed into filter segments using standard filter making equipment. For comparison, conventional cellulose acetate (CA) tow filter segments with similar values of denier per filament (dpf) and total denier are made.

In a first test, the water absorption by exposure to water of a PHA filter segment and a CA filter segment according to the present invention is compared. For each filter segment, the plug wrap is removed and the filter segment is attached to the probe of a surface tensiometer (KRUSS surface tensiometer, model K100). The filter segment is moved downward towards the container of water by the probe and automatically stops when the filter segment comes into contact with water. The filter segment is held in contact with water for 300 seconds to allow the filter material to absorb water, and then the filter segment is weighed to determine the amount of water absorbed during the test period. As shown in Table 2 below, for each of the PHA filter segment and the CA filter segment, this test was repeated three times and the average value of water uptake was calculated:

Thus, the amount of water absorbed by the PHA filter segment according to the invention during the test was less than 40% of the amount of water absorbed by the CA filter segment. Thus, this test demonstrates a significantly reduced affinity for water of the PHA filter segment according to the present invention compared to the conventional CA filter segment.

In a second test, moisture absorption by moisture exposure of a PHA filter segment and a CA filter segment according to the present invention is compared. For each filter segment, the plug wrap is removed and the fibers forming the filter segment are placed in a Petri dish and exposed to air at 22° C. and 50% relative humidity for 70 hours. This is done on a vapor sorption analyzer (ProUmid SPSx-1μ). For each filter segment, the weight of the fiber is measured at the beginning of the test and the change in weight over time due to absorption of water vapor by the fiber is measured. For each of the PHA filter segment and the CA filter segment, the percent mass difference value (%dm) of the sample is calculated, which expresses the weight gain of the sample as a percentage of the original weight. The values of %dm for each sample at the end of the 70 hour test are shown in Table 3 below:

The results demonstrate that the amount of water vapor absorbed by the cellulose acetate fibers during the 70 hour test is over 50 times greater than the amount of water vapor absorbed by the PHA fibers. The PHA fibers absorbed very little water vapor during testing. This further demonstrates the significantly reduced affinity of water of the PHA filter segment according to the invention compared to the conventional CA filter segment.

In a third test, the absorption of water from mainstream smoke by a PHA filter segment according to the present invention and a conventional CA filter segment is compared. For each filter segment, a conventional smoking article is made with a single segment of filtration material forming the combustible tobacco rod and filter as described above with reference to FIG. 3 . Each smoking article is then smoked in a cigarette-smoking machine under the ISO conditions set out in ISO 3308:2000 (puff volume 35 ml; puff duration of 2 seconds every 60 seconds), and analysis of the generated smoke is performed. For each filter segment, the amount of water in the mainstream smoke collected during the smoking test is measured, as shown in Table 4:

This demonstrates that when smoked under equivalent conditions, a smoking article comprising a PHA filter segment produces mainstream smoke having a moisture content approximately 20% higher than that of mainstream smoke from a smoking article comprising a CA filter segment . This demonstrates that the PHA filter segment absorbs less water from mainstream smoke than the CA filter segment, reducing the potential problems of dry smoke as described above.

Claims (14)

An aerosol-generating article comprising:
aerosol-generating substrates; and
a filter axially aligned with the aerosol-generating substrate, the filter comprising at least one filter segment of a filtration material formed of a plurality of fibers comprising a polyhydroxyalkanoate compound, the fibers comprising the filter segment and wherein the at least one filter segment comprises at least 20% by weight of the polyhydroxyalkanoate compound. The aerosol of claim 1 , wherein the plurality of fibers comprising the polyhydroxyalkanoate compound have a round cross-sectional shape and provide a total external surface area within the filter segment of 0.12 square meters/gram to 0.16 square meters/gram. occurrence goods. The method of claim 1 , wherein the plurality of fibers comprising the polyhydroxyalkanoate compound have a Y-shaped cross-sectional shape and provide a total external surface area within the filter segment of 0.21 square meters/gram to 0.28 square meters/gram. which is an aerosol-generating article. 4. The aerosol-generating article according to any one of claims 1 to 3, wherein the fibers comprising the polyhydroxyalkanoate compound have a denier/filament (dpf) of 3.2 to 5.0. 5. The aerosol-generating article according to any one of claims 1 to 4, wherein the total denier of the fibers comprising the polyhydroxyalkanoate compound is between 25,000 and 40,000. 6 . The aerosol-generating article according to claim 1 , wherein the filtration material further comprises a plurality of fibers of at least one additional biodegradable polymer. 7. The resistance to aspiration (RTD) of the filter segment comprising the plurality of fibers comprising the polyhydroxyalkanoate compound is from 10 mm H ₂ O to about 40. mm H ₂ O, an aerosol-generating article. 8. The filter segment according to any one of claims 1 to 7, wherein said filter segment comprising said plurality of fibers comprising said polyhydroxyalkanoate compound is at least 50% in an aqueous medium when tested according to ISO 14851. An aerosol-generating article having biodegradability. 9. The aerosol generating according to any one of claims 1 to 8, wherein the filter segment comprising the plurality of fibers comprising the polyhydroxyalkanoate compound further comprises at least 5% by weight polyethylene glycol. article. 10. The aerosol-generating article according to any one of claims 1 to 9, wherein the filter segment comprising the plurality of fibers comprising the polyhydroxyalkanoate compound has an average radial hardness of at least 80%. 11. The wrapper according to any one of claims 1 to 10, wherein said filter segment comprising said plurality of fibers comprising said polyhydroxyalkanoate compound has a basis weight of at least 100 grams per square meter (gsm). an aerosol-generating article surrounded by 12. The aerosol-generating article according to any one of the preceding claims, wherein the filter segment comprising the plurality of fibers comprising the polyhydroxyalkanoate compound is in the form of a hollow tubular element. 13. The aerosol-generating article according to any one of the preceding claims, wherein the aerosol-generating substrate is a tobacco rod having a length of 5 mm to about 15 mm. A filter for an aerosol-generating article, the filter comprising at least one filter segment of a filtration material formed of a plurality of fibers comprising a polyhydroxyalkanoate compound, wherein the fibers are within the filter segment from 0.12 square meters/gram to about 0.28 square meters. A filter for an aerosol-generating article, wherein the filter provides a total external surface area in meters/gram, wherein the at least one filter segment comprises at least about 20% by weight of a polyhydroxyalkanoate compound.

Images