WO2025210580A1

WO2025210580A1 - Filter element

Info

Publication number: WO2025210580A1
Application number: PCT/IB2025/053574
Authority: WO
Inventors: Hugo AZINHEIRA; Anang JUNAIDI; Agus FAHRONI; Muriyono -; Arief RAHMAN; Mohammad ADIMAS
Original assignee: Filtrona Pte Ltd
Current assignee: Filtrona Pte Ltd
Priority date: 2024-04-05
Filing date: 2025-04-04
Publication date: 2025-10-09
Anticipated expiration: 2026-10-05

Abstract

The present invention provides a filter element (100) for an aerosol generating article comprising: a first segment (105) comprising a longitudinally extending hollow tube comprising a sheet of material; a second segment (110) comprising a longitudinally extending core comprising a filtering material (115); wherein the first segment (105) is joined to the second segment (110); and wherein the filtering material (115) comprises biodegradable material.

Description

Filter element

Background

The present invention relates to a filter element for an aerosol generating article.

The use of filter elements in aerosol generating articles is known in the art. For example, filter elements can function to remove unwanted compounds from an aerosol and/or cool the aerosol, while providing the appearance and mouth feel of a traditional cigarette. Filter elements typically comprise a longitudinally extending cylindrical core of filtering material.

An aerosol generating article typically includes a rod of aerosol generating material, such as a tobacco based material, together with a filter and/or cooling element. The aerosol generating article forms part of an aerosol generating system which also includes a heat source for heating the aerosol generating material to generate an aerosol that is inhaled by the user.

For users of aerosol generating systems, it is desirable for the temperature of the aerosol leaving the aerosol generating article to remain constant during use.

Previously, cooling elements have been used to control the thermal properties of the aerosol generated by an aerosol generating article. Cooling elements may provide a cooling function by lowering the temperature of the aerosol as it passes along the length of the cooling element. However, aerosol generating articles with such cooling elements often lead to undesirable aerosol temperature stability during use, particularly during extended use. For example, such cooling elements may lead to a continuous decrease in aerosol temperature throughout use, which is undesirable for the user.

Thus, there is a need for a filter element which acts to both cool the aerosol and filter the aerosol, while maintaining a more stable aerosol temperature during use.

Summary of invention

In a first aspect of the present invention there is provided a filter element for an aerosol generating article comprising: a first segment comprising a longitudinally extending hollow tube comprising a sheet of material; a second segment comprising a longitudinally extending core comprising a filtering material; wherein the first segment is joined to the second segment; and wherein the filtering material comprises biodegradable material.

The applicant has found that during use, when the filter element is used as part of an aerosol generating system, aerosol leaving the aerosol generating system exhibits improved thermal properties throughout its use.

During use, aerosol initially passes through the first segment and then passes through the second segment, and the aerosol passes through the second segment with a lower velocity than the first segment. Without wanting to be bound by theory, it is hypothesised that the difference in pressure drop between the first segment and the second segment helps the aerosol to slow down and cool down, especially during the first few puffs. As the thermal capacity of the second segment is attained during use, the cooling rate reduces, leading to the aerosol having a stable temperature throughout its remaining use.

The applicant has also found that the aerosol having a stable temperature delivers more consistent organoleptic properties, including a more consistent taste sensation to the user.

The first segment may comprise one or more sheet(s) of material. The longitudinally extending hollow tube may comprise one or more sheet(s) of material. The one or more sheet(s) of material may define the longitudinally extending hollow tube. The longitudinally extending hollow tube may be formed from one or more sheet(s) of material.

The one or more sheet(s) of material may be wound about the central longitudinal axis of the first segment.

The first segment may comprise a helically wound sheet of material. The longitudinally extending hollow tube may comprise a helically wound sheet of material. The helically wound sheet of material may define the longitudinally extending hollow tube.

The helically wound sheet of material may be a sheet of material that extends helically about the longitudinal axis of the first segment, such that the helically wound sheet of material partially overlaps with itself at successive points along the longitudinal length of the first segment.

The helically wound sheet of material may be wound about the longitudinal axis of the first segment, for example wound about the longitudinal axis of the first segment in a spiral at an oblique angle to the longitudinal axis of the first segment. A portion of the helically wound sheet of material may overlap with itself on each successive helical turn, such that there are no gaps between the turns. It will be appreciated that, without gaps between successive helical turns, the helically wound sheet of material is substantially tubular (e.g., tubular) in shape (i.e. , the helically wound sheet of material forms the hollow tube). The helically wound sheet of material may overlap with itself at successive points along the longitudinal length of the hollow tube.

The longitudinally extending hollow paper tube may comprise a rolled sheet of material which defines the longitudinally extending hollow tube. The sheet of material may be rolled along its longitudinal length to thereby define the longitudinally extending hollow tube.

The sheet of material may overlap with itself. A free longitudinal edge of the sheet of material may overlap with another part of the same sheet of material and may be adhered to the sheet of material to thereby define the longitudinally extending hollow tube.

The first segment may comprise one or more sheet(s) of material, for example one, two, three, four, five, six, seven, eight, nine or ten sheet(s) of material. The one or more sheet(s) of material may each be helically wound or the one or more sheet(s) may be helically wound together. For example, a number of stacked sheets may be helically wound together to thereby define the longitudinally extending hollow tube.

The one or more sheet(s) of material may each be rolled to define the longitudinally extending hollow tube, or the one or more sheet(s) may be rolled together to define the longitudinally extending hollow tube. For example, a number of stacked sheets may be rolled together to thereby define the longitudinally extending hollow tube.

The sheet(s) of material, as described above and herein, may comprise one or more of hemp, lyocell, flax, cotton, sisal, jute, abaca, cotton, coconut fibres, bamboo fibres and starch. Preferably, the sheet(s) of material, as described above, is a sheet(s) of paper.

The first segment may not comprise cellulose acetate.

The paper, may comprise any paper (in any form) which is conventionally used in filters or filter elements. The paper may be, for example, filtering paper, aperture paper, crepe paper, air-laid paper or machine glazed paper etc. of varying grades. The fibre of the paper may be a natural fibre (e.g. flax, hemp, sisal, jute, abaca, cotton, coconut fibres, bamboo fibres or starch (e.g. from corn), or tobacco).

The first segment may have a pressure drop value of from zero millimetres water gauge per millimetre (mmWg/mm) to 1 mmWg/mm, for example from zero mmWg/mm to 0.5 mmWg/mm, for example from 0.1 mmWg/mm to 0.3 mmWg/mm, for example from 0.1 mmWg/mm to 0.2 mmWg/mm. The first segment may have a pressure drop value of from zero mmWg/mm to 0.3 mmWg/mm, for example from zero mmWg/mm to 0.2 mmWg/mm, for example from zero mmWg/mm to 0.1 mmWg/mm. The first segment may have a pressure drop value of zero mmWg/mm.

Pressure drop may be measured using a Cerulean QTM module #6 device and is defined as the static pressure difference between the two ends of the specimen when it is traversed by an air flow under steady conditions in which the volumetric flow is 17.5 ml/s at the output end.

The first segment may facilitate the passage of aerosol into other filter elements (or segments) when used as part of an aerosol generating article (i.e. , the aerosol may pass through the channel of the hollow tube into other segments). It will be appreciated that if the first segment is facilitating the passage of aerosol into other filter elements (or segments) of an aerosol generating article, the channel of the hollow tube may not contain any object which may substantially restrict the aerosol. In other words, the channel of the hollow tube may be empty. Thus, there may be substantially no retention of the aerosol by the first segment, for example no retention of the aerosol by the first segment. It will further be appreciated that, when assembled with further filter segments into a multi-segment product, the first segment may contribute substantially zero, for example zero, to the pressure drop of the multi-segment product due to the lack of or minimal retention of aerosol by the first segment.

The first segment may act as a reservoir wherein the aerosol is concentrated within the channel of the hollow tube. Without wanting to be bound by theory, it is thought that when aerosol has been generated, the aerosol is collected and concentrated within the channel of the hollow tube. The concentrated aerosol is then drawn from the hollow tube to the mouth end of the filter element.

The first segment may be substantially cylindrical, for example cylindrical. The first segment may have a circumference of from 12 mm to 30 mm, for example from 15 mm to 28 mm, for example from 17 mm to 25 mm, for example from 20 mm to 25 mm, for example from 22 mm to 23 mm, for example from 22 mm to 22.5 mm, for example 22.25 mm. The first segment may have a length of from 6 mm to 35 mm, for example from 6 mm to 22 mm, for example from 6 mm to 18 mm, for example from 6 mm to 15 mm, for example from 7 mm to 12 mm, for example from 7 mm to 10 mm, for example from 8 mm to 10 mm, for example 9 mm.

The average wall thickness of the first segment may be from 0.2 mm to 3.0 mm, for example from 0.5 mm to 2.5 mm, for example from 1.0 mm to 2.0 mm, for example from 1.3 mm to 1.5 mm. The wall thickness is defined herein as the distance between the outer surface and the inner surface of the hollow tube.

The internal diameter of the first segment may be from 1.5 mm to 10 mm, for example from 2 mm to 9 mm, for example from 3 mm to 8 mm, for example from 4 mm to 7 mm, for example 5 mm, or 6 mm. The internal diameter is defined herein as the distance between diametrically opposed points on the inner surfaces of the hollow tube at its widest point.

The first segment may comprise an additive. For example, the longitudinally extending hollow tube may comprise an additive.

The additive may be located on or in the first segment. The additive may be located on or in the longitudinally extending hollow tube. The additive may be located, for example disposed, on the inner wall of the longitudinally extending hollow tube. The additive may be located, for example disposed, on the one or more sheet(s) of material of the first segment. For example, the additive may be located, for example disposed, on the one or more sheet(s) of helically wound material of the first segment.

The additive may be dispersed throughout transverse cross section of the wall of the longitudinally extending hollow tube. For example, the additive may be dispersed throughout the transverse thickness of the one or more sheet(s) of material.

The additive may be a vapour modifying agent which may modify or enhance the sensory properties of the vapour. The vapour modifying agent may impart an additional taste or aroma to the vapour passing through the filter element or first segment, or it may function to supress certain flavours or aromas. The additive may be a liquid additive. The additive may be a flavouring agent. Examples, of suitable flavouring agents include menthol, spearmint, clove, nutmeg, cinnamon, lemon, chocolate, peach, strawberry, vanilla and the like. The flavouring agent may be a liquid composition which includes only the flavouring agent, or the liquid composition may further comprise a liquid carrier such as an alcohol, for example propylene glycol, or other organic solvent. The additive may comprise a polyethylene glycol compound.

The additive may be applied to the first segment using techniques known in the art.

The second segment may comprise a gathered sheet of biodegradable material. The biodegradable material may be a cellulosic material, preferably paper. The term “biodegradable” refers to the filtering material being able to exhibit a biodegradation of at least 90% after 6 months under controlled composting conditions (see ISO14855-1 Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide).

Preferably, the biodegradable material, such as paper, used in the filtering material of the present invention is “readily biodegradable” and has an enhanced biodegradability compared to cellulose acetate. Therefore, the present invention provides a filtering material of enhanced biodegradability, and thus is more environmentally friendly.

The phrase “readily biodegradable” refers to the filtering material and filter element being able to disintegrate rapidly and completely biodegrade when immersed in water. Preferably the element has the ‘Ready Biodegradability’ level of biodegradability as measured according to OECD 301 B ‘Ready Biodegradability’ method (modified Sturm test), which is well known in the art. The phase “readily biodegradable” will here be understood to mean ‘Ready Biodegradability’ level of biodegradability.

The filtering material of the second segment may further comprise a hydrophobic material. The hydrophobic material may be any suitable hydrophobic material. For example, the hydrophobic material may be a polymer or a blend of polymers. Preferably, the hydrophobic material is a starch, such as a modified starch, for example oxidized starch (E1404). A starch such as a modified starch is preferred as it is inert and provides a non-plastic hydrophobic coating. The hydrophobic material may be present in an amount from 0.01% to 50% weight of hydrophobic material with respect to weight of the second segment (w/w), for example from 0.01 % to 20% w/w, for example from 0.1 % to 20% w/w, for example from 5% to 20% w/w, for example from 10% to 20% w/w, for example from 0.1% to 10% w/w, for example from 0.1% to 5% w/w, for example from 0.5% to 2.5% w/w.

The hydrophobic material may be distributed throughout the longitudinally extending core of the second segment. Without wanting to be bound by theory, the hydrophobic material may enhance the cooling effect of the filtering material by causing water vapour to condense within the segment.

The applicant has found that by using a biodegradable material, such as paper, coated in a hydrophobic material to form the second segment of the filter element, a segment can be produced in which the hydrophobic material is evenly distributed throughout the segment. This may provide an optimal level of aerosol cooling and filtration.

The biodegradable material, such as paper, is preferably readily biodegradable. The paper, may comprise any paper (in any form) which is conventionally used in filters or filter elements. The paper may be, for example, filtering paper, aperture paper, crepe paper, air-laid paper or machine glazed paper etc. of varying grades. The fibre of the biodegradable material, such as paper, may be a natural fibre (e.g. flax, hemp, sisal, jute, abaca, cotton, coconut fibres, bamboo fibres or starch (e.g. from corn), or tobacco). The paper may be woven or nonwoven, or in the form of a coherent web of paper, or a longitudinally corrugated and/or fibrillated web of paper e.g. gathered laterally into, and held, in plug form. The biodegradable material, such as paper, may be in the form of a coherent web comprising a first biodegradable material, such as paper, and a second biodegradable material. The biodegradable material may be in the form of a blend of different biodegradable material. The paper may have the same or a similar structure to those papers sold under the trademark Myria® or Puracel® (of Filtrona Pte. Ltd.). The paper may be coated with a hydrophobic coating or hydrophobic material.

The paper may have a basis weight from 20 grams per square metre (gsm) to 200 gsm. For example, the paper may have a basis weight from 40 gsm to 180 gsm, for example from 60 gsm to 160 gsm, for example from 80 gsm to 140 gsm, for example from 100 gsm to 120 gsm, for example from 20 gsm to 60 gsm, for example from 30 gsm to 40 gsm.

The second segment may have a pressure drop value of from 1.25 mmWg/mm to 10 mmWg/mm, for example from 1.25 mmWg/mm to 5 mmWg/mm, for example from 1.5 mmWg/mm to 5 mmWg/mm, for example from 2 mmWg/mm to 4.5 mmWg/mm, for example from 2 mmWg/mm to 4 mmWg/mm, for example from 2 mmWg/mm to 3.5 mmWg/mm, for example from 2 mmWg/mm to 3 mmWg/mm, for example 2.5 mmWg/mm. The second segment may have a pressure drop value of from 2.5 mmWg/mm to 4 mmWg/mm, for example from 2.5 mmWg/mm to 3.5 mmWg/mm, for example from 2.5 mmWg/mm to 3 mmWg/mm, for example 2.5 mmWg/mm.

The second segment may have a circumference of from 12 mm to 30 mm, for example from 15 mm to 28 mm, for example from 17 mm to 25 mm, for example from 20 mm to 25 mm, for example from 22 mm to 23 mm, for example from 22 mm to 22.5 mm, for example 22.25 mm. The second segment may have a length of from 6 mm to 35 mm, for example from 6 mm to 22 mm, for example from 6 mm to 18 mm, for example from 6 mm to 15 mm, for example from 7 mm to 12 mm, for example from 7 mm to 10 mm, for example from 8 mm to 10 mm, for example 9 mm.

The second segment as described herein may further comprise an outer wrapper engaged around the longitudinally extending core. The outer wrapper may be a paper, for example a plugwrap paper. The paper (e.g., plugwrap paper) may have a basis weight of from 20 gsm to 160 gsm. The paper, e.g. plugwrap paper, may have a basis weight of from 24 gsm to 150 gsm, for example from 25 gsm to 100 gsm.

The second segment may be substantially cylindrical, for example cylindrical.

The first segment and the second segment may be discrete and joined together such that an end of the first segment may abut an end of the second segment. Alternatively, the first segment and the second segment may be integral.

The first segment and the second segment may be joined together by a sheet of paper which engages around the first segment and the second segment. Preferably, the paper has a basis weight of from 20 gsm to 160 gsm. The paper, may have a basis weight of from 24 gsm to 150 gsm, for example from 25 gsm to 100 gsm, for example a basis weight of 27 gsm. The sheet of paper may engage around the full length of the first and second segments.

Preferably, the hardness of the joined first and second segments is from 85% to 95% hardness, for example from 90% to 95% hardness, for example from 92% to 94% hardness, for example 93% hardness. Herein hardness is a measurement of the extent to which the element deforms following application of a given pressure for a given time. Hardness is measured using a Cerulean QTM module 7 device. A preload is applied to the element and the point of contact diameter (DP) is measured. A higher load is then applied and the depressed diameter (DL) is measured after a given time or once a slope threshold is reached. The hardness is calculated as: %H = (DL/DP) x 100. The load cell used with the QTM module 7 device is 300 grams.

The total combined length of the first and second segments may be from 12 mm to 70 mm, for example from 12 mm to 40 mm, for example from 12 mm to 30 mm, for example from 12 mm to 25 mm, for example from 12 mm to 22 mm, for example from 14 mm to 20 mm, for example from 16 mm to 20 mm, for example 17 mm, for example 18 mm, for example 19 mm.

The circumference of the first and second segments, when joined together by a sheet of paper, may be from 12 mm to 30 mm, for example from 15 mm to 28 mm, for example from 17 mm to 25 mm, for example from 20 mm to 25 mm, for example from 22 mm to 23 mm, for example from 22.5 mm to 23 mm, for example 22.55 mm.

The pressure drop value of the first and second segments when joined, may be from 1.25 mmWg/mm to 11 mmWg/mm, for example from 1.25 mmWg/mm to 6 mmWg/mm, for example from 1 .25 mmWg/mm to 4 mmWg/mm for example from 1 .25 mmWg/mm to 2 mmWg/mm, for example from 1.25 mmWg/mm to 1.75 mmWg/mm, for example 1.5 mmWg/mm.

The difference in pressure drop value between the first and the second segments, may be from 0.25 mmWg/mm to 10 mmWg/mm, for example from 0.25 mmWg/mm to 8 mmWg/mm, for example from 0.25 mmWg/mm to 5 mmWg/mm, for example from 0.5 mmWg/mm to 4 mmWg/mm, for example from 1 mmWg/mm to 3 mmWg/mm, for example from 1.25 mmWg/mm to 2.5 mmWg/mm, for example from 1.5 mmWg/mm to 2 mmWg/mm, for example 1.5 mmWg/mm, for example 2 mmWg/mm, for example 2.5 mmWg/mm.

The weight of the first and second segments when joined together by a sheet of paper may be from 83 mg to 250 mg, for example from 100 mg to 208 mg, for example from 117 mg to 167 mg, for example 140 mg. When in use, the first segment is preferably positioned upstream from the second segment so that the first segment is closer to an aerosol generating substance than the second segment, and the second segment is closer to the mouth of the user than the first segment.

Herein the term “upstream” means towards the end of the filter element or aerosol generating article that is closest to the aerosol generating substance during use. The term “downstream” means towards the end of the filter element or aerosol generating article closest to the mouth of the user, during use.

The filter element may comprise: a first segment and a second segment as described herein; and a third segment; wherein the third segment comprises a longitudinally extending core comprising filtering material; and wherein the third segment is joined to the second segment.

The filtering material of the third segment may comprise cellulose acetate, for example cellulose acetate tow.

The second segment and the third segment may be discrete and joined together such that the end of the second segment, which is the opposite end to the end that is joined to the first segment, may abut an end of the third segment.

The third segment may have a pressure drop value of from 5 mmWg/mm to 50 mmWg/mm, for example from 5 mmWg/mm to 30 mmWg/mm, for example from 5 mmWg/mm to 20 mmWg/mm, for example from 7 mmWg/mm to 15 mmWg/mm, for example from 9 mmWg/mm to 12 mmWg/mm, for example from 10 mmWg/mm to 11 mmWg/mm, for example 10.8 mmWg/mm.

The third segment may have a length from 6 mm to 40 mm, for example from 6 mm to 30 mm, for example from 6 mm to 20 mm, for example from 8 mm to 15 mm, for example from 8 mm to 12 mm, for example from 9 mm to 11 mm, for example 10 mm.

The third segment may be substantially cylindrical, for example cylindrical.

The third segment as described herein may further comprise an outer wrapper engaged around the longitudinally extending core. The outer wrapper may be a paper, for example a plugwrap paper. The paper may have a basis weight of from 20 gsm to 160 gsm. The paper may have a basis weight of from 24 gsm to 150 gsm, for example from 25 gsm to 100 gsm, for example 27 gsm. The filter element may comprise a first, second and third segment as described herein, wherein the first and second segments are joined by a first sheet of paper which engages around the first segment and the second segment; and wherein the third segment is joined to the second segment by a second sheet of paper which engages around the first sheet of paper and the third segment. The sheet of paper may engage around the full length of the first, second and third segments.

When in use, the first segment is preferably positioned upstream from the second segment and the third segment is preferably positioned downstream from the second segment. In this configuration, the first segment is closer to the aerosol generating substance than the second segment, and the third segment is closer to the mouth of the user than the second segment.

In a further aspect of the present invention, there is provided an aerosol generating article comprising: a filter element as described herein; and a fourth segment comprising a longitudinally extending core comprising an aerosol generating substance; wherein the fourth segment is joined to the first segment of the filter element described herein.

The fourth segment may comprise tobacco, for example reconstituted tobacco.

The fourth segment may be substantially cylindrical, for example cylindrical.

The first segment and the second segment may be joined (abutted) together by a first sheet of paper which engages around the first segment and the second segment; the third segment may be joined (abutted) to the second segment by a second sheet of paper, and the fourth segment may be joined (abutted) to the first segment by the second sheet of paper; and the second sheet of paper may engage around the first sheet of paper and the third and fourth segments.

The aerosol generating article as described herein may have a pressure drop value of from 6 mmWg/mm to 100 mmWg/mm, for example from 10 mmWg/mm to 80 mmWg/mm, for example from 20 mmWg/mm to 70 mmWg/mm, for example from 25 mmWg/mm to 60 mmWg/mm, for example from 25 mmWg/mm to 50 mmWg/mm, for example from 25 mmWg/mm to 45 mmWg/mm, for example from 30 mmWg/mm to 40 mmWg/mm, for example 35 mmWg/mm, for example 37.5 mmWg/mm. The aerosol generating article as described herein may have a circumference of from 12 mm to 30 mm, for example from 15 mm to 28 mm, for example from 17 mm to 25 mm, for example from 20 mm to 25 mm, for example from 22 mm to 23 mm, for example from 22.5 mm to 23 mm, for example 22.85 mm.

The aerosol generating article as described herein may have a length of from 28 mm to 110 mm, for example from 28 mm to 80 mm, for example from 30 mm to 60 mm, for example from 34 mm to 55 mm, for example from 36 mm to 50 mm, for example from 38 mm to 48 mm, for example from 38 mm to 45 mm, for example from 38 mm to 42 mm, for example from 39 mm to 41 mm, for example 40 mm.

The aerosol generating article as described herein may have a weight from 375 mg to 800 mg, for example from 400 mg to 750 mg, for example from 450 mg to 700 mg, for example from 500 mg to 650 mg, for example from 550 mg to 625 mg, for example from 575 mg to 620 mg, for example from 590 mg to 610 mg, for example 600 mg.

In a further aspect of the invention, there is provided an aerosol generating system comprising: an aerosol generating article as described herein and a heat source.

The heat source may be a heating element, an induction heating source or the like.

The aerosol generating system may further comprise a power source connected to the heat source. During use, the heat source heats the aerosol generating material, such as reconstituted tobacco, to generate an aerosol.

In a further aspect of the invention, there is provided a method for making a filter element for an aerosol generating article comprising the steps of: advancing a first segment in a longitudinal direction; advancing a second segment in a longitudinal direction; engaging a first sheet of paper around the first and second segments; wherein the first segment comprises a longitudinally extending hollow tube comprising a sheet of material; wherein the second segment comprises a longitudinally extending core comprising a filtering material; and wherein the filtering material comprises a biodegradable material.

The first segment may advance continuously. The second segment may advance continuously. The first segment and second segment may be introduced via one or more hopper(s). Adhesive may be used to secure the first sheet of paper around the first and second segments. The adhesive may be applied to the first sheet of paper by methods known in the art.

The method may comprise advancing an alternating and continuous array of first and second segments in a longitudinal direction; securing the first sheet of paper around the segments to form a continuous rod; and cutting the continuous rod to form a filter element comprising a first segment and a second segment.

The first and second segments may be as defined herein. The first segment may be made according to a method comprising the steps of: advancing a sheet of material in a longitudinal direction; winding the sheet of material around a cylindrical shaping rod, such that the sheet of material forms a longitudinally extending hollow tube; and cutting the continuous rod to form individual segments.

For example, the first segment may be made according to a method comprising steps of: advancing a sheet of material in a longitudinal direction; rolling the sheet of material about the shaping rod, such that the sheet of material overlaps with itself, wherein a free longitudinal edge of the sheet of material overlaps with another part of the same sheet of material to thereby define the longitudinally extending hollow tube; and cutting the continuous rod to form individual segments.

The first segment may be made according to a method comprising the steps of: advancing a sheet of material in a longitudinal direction; helically winding the sheet of material around a shaping rod, such that the sheet of material partially overlaps with itself on successive helical turns, thereby forming a longitudinally extending hollow tube; and cutting the continuous rod to form individual segments.

The sheet of material may advance continuously.

The sheet of material may be drawn from a source (e.g., a roll of sheet material) before being advanced towards the shaping rod.

The method may comprise advancing one or more sheet(s) of material, for example one, two, three, four, five, six, seven, eight, nine or ten sheet(s) of material. The method may comprise advancing at least 2 sheets of material, for example at least 3 sheets of material, for example at least 4 sheets of material.

The method may comprise applying adhesive to the advancing sheet of material. The adhesive may be applied to a surface of the advancing sheet of material. The adhesive may be applied to the advancing sheet of material before the advancing sheet of material is wound around the shaping rod. For example, the adhesive may be applied to the sheet of material at a gluing station before the advancing sheet of material is wound around the shaping rod. The adhesive may be sprayed onto the sheet of material, for example sprayed onto a surface of the sheet of material, for example along a longitudinal edge of the sheet of material. The adhesive may be a hot melt or water-based adhesive (e.g., ethyl vinyl acetate) as is known in the art.

The adhesive may be applied to portions of the sheet of material that will overlap with itself (e.g., at successive helical turns) when the sheet of material is helically wound around the shaping rod. The adhesive may be applied to portions of the sheet of material (e.g., the free longitudinal edge) that will overlap with itself when the sheet of material is rolled around the shaping rod.

The shaping rod may also be referred to as a mandrel. The shaping rod may be substantially cylindrical, for example cylindrical. The shaping rod may comprise an outer surface which defines the internal diameter of the hollow tube.

The shaping rod may have a diameter of from 1.5 mm to 10 mm, for example from 2 mm to 9 mm, for example from 3 mm to 8 mm, for example from 4 mm to 7 mm, for example 5 mm or 6 mm.

The internal diameter of the hollow tube may be from 1.5 mm to 10 mm, for example from 2 mm to 9 mm, for example from 3 mm to 8 mm, for example from 4 mm to 7 mm, for example 5 mm or 6 mm.

The sheet of material may have a width of from 10 mm to 20 mm, for example from 12 mm to 18 mm, for example from 14 mm to 16 mm, for example 15 mm.

The sheet of material may be helically wound around the outer surface of the shaping rod, for example wound about the longitudinal axis of the shaping rod in a spiral at an oblique angle to the longitudinal axis of the shaping rod. On each successive helical turn around the shaping rod, a first portion of the sheet of material will partially overlap with a second portion of the sheet of material, such that there are no gaps between successive turns of the sheet of material. The overlapping portions of the sheet of material may be secured to each other by adhesive.

The sheet of material may be rolled around the outer surface of the shaping rod, for example rolled around the longitudinal axis of the shaping rod. On each roll around the shaping rod, the sheet of material will overlap with another part of the same sheet of material. The overlapping portions may be secured to each other by adhesive.

The sheet of material, as described above, may comprise one or more of hemp, lyocell, flax, cotton, sisal, jute, abaca, cotton, coconut fibres, bamboo fibres and starch. Preferably, the sheet of material, as described above, is a sheet of paper.

The sheet material may not comprise cellulose acetate.

The paper may comprise plant based fibres, for example one or more of flax, hemp, jute, sisal, abaca, cotton, coconut, bamboo, starch or wood pulp. The paper may be formed from plant based fibres, for example one or more of flax, hemp, jute, sisal, abaca, cotton, coconut, bamboo, starch or wood pulp. The paper may be a filter paper or a lyocell/viscose based paper.

In the case in which the first segment comprises an additive, the additive may be applied to the first segment after the first segment is formed. Alternatively, the additive may be applied to the sheet of material before the sheet of material is wound around the shaping rod. The additive may be applied using methods known in the art.

The second segment may be made according to a method comprising the steps of: gathering one or more sheets of biodegradable material into a longitudinally extending core; and wrapping the longitudinally extending core with a sheet of biodegradable material.

The longitudinally extending core may be cylindrical. The biodegradable material may be paper. The paper may be woven or non-woven, or in the form of a coherent web of material, or a longitudinally corrugated and/or fi bril lated web of paper e.g. gathered laterally into, and held, in plug form.

The biodegradable material may be coated with hydrophobic material. The hydrophobic coating may be applied to the biodegradable material via any of the standard coating methods known in the art.

The biodegradable material may be coated in hydrophobic material before being gathered and held in plug form. The biodegradable material may be coated in hydrophobic material after being gathered and held in plug form.

In the case of the filter element comprising a first segment, a second segment and a third segment as described herein, the method of making such a filter element may comprise the steps of: forming a filter element comprising a first segment and a second segment joined by a first sheet of paper engaged around the first segment and the second segment, according to the methods described above; advancing a third segment in a longitudinal direction; and joining the third segment to the second segment by engaging a second sheet of paper around the first sheet of paper and the third segment; wherein the third segment comprises filtering material.

The third segment may be introduced via a hopper. The third segment may be advanced after the first and second segments have advanced.

Adhesive may be used to secure the second sheet of paper around the first sheet of paper and the third segment. The adhesive may be applied to the second sheet of paper by methods known in the art.

The method may comprise advancing a first segment in a longitudinal direction, followed by advancing a second segment in a longitudinal direction, followed by advancing a third segment in a longitudinal direction; engaging a first sheet of paper around the first and second segments to thereby join the first segment to the second segment, followed by securing a second sheet of paper around the first sheet of paper and the third segment to thereby join the second segment to the third segment.

The method may comprise advancing an alternating and continuous array of first, second and third segments in a longitudinal direction; engaging a first sheet of paper around the first and second segments; engaging a second sheet of paper around the first sheet of paper and the third segment to form a continuous rod; and cutting the continuous rod to form a filter element comprising a first segment, a second segment and a third segment.

The third segment comprising filtering material, may be manufactured by methods known in the art. The third segment may comprise cellulose acetate filtering material, for example cellulose acetate tow.

There is also provided a method of making an aerosol generating article which comprises a first segment, a second segment, a third segment and fourth segment, as described herein. The method of making such an aerosol generating article may comprise the steps of: forming a filter element comprising a first segment and a second segment joined by a first sheet of paper engaged around the first segment and the second segment, according to the methods described above; and further comprising the steps of: advancing a fourth segment in a longitudinal direction; advancing the first and second segments in a longitudinal direction; advancing a third segment in a longitudinal direction; and engaging a second sheet of paper around the first sheet of paper and the third and fourth segments; wherein the fourth segment comprises a longitudinally extending core comprising an aerosol generating substance; wherein the fourth segment is joined to the first segment, and the third segment is joined to the second segment.

The fourth segment may be introduced to via a hopper. The fourth segment may be advanced before the first, second and third segments have advanced.

Adhesive may be used to secure the second sheet of paper around the first sheet of paper and the third and fourth segments. The adhesive may be applied to the second sheet of paper by methods known in the art. The method may comprise advancing a fourth segment in a longitudinal direction, followed by advancing a first segment in a longitudinal direction, followed by advancing a second segment in a longitudinal direction, followed by advancing a third segment in a longitudinal direction; engaging a first sheet of paper around the first and second segments, followed by engaging a second sheet of paper around the fourth segment, the first sheet of paper and the third segment.

The method may comprise advancing an alternating and continuous array of a fourth segment, a first segment, a second segment and a third segment in a longitudinal direction; engaging a first sheet of paper around the first and second segments; engaging a second sheet of paper around the first sheet of paper and the third segment and the fourth segment to form a continuous rod; and cutting the continuous rod to form an aerosol generating article comprising a first segment, a second segment, a third segment and a fourth segment.

The fourth segment comprising an aerosol generating substance, may be manufactured by methods known in the art.

The present invention will now be described in further detail by reference to the attached Figures in which:

Figure 1a shows a schematic view of a filter element for an aerosol generating article according to an embodiment of the invention.

Figure 1b shows a cross-sectional view through the section A-A of figure 1a.

Figure 1c shows a side profile view of the filter element illustrated in figure 1a.

Figure 2a shows a schematic view of a filter element for an aerosol generating article according to a further embodiment of the invention.

Figure 2b shows a side profile view of the filter element illustrated in figure 2a.

Figure 3a shows a schematic view of an aerosol generating article according to the invention.

Figure 3b shows a side profile view of the aerosol generating article illustrated in figure 3a. Figure 4 shows a graph of how the aerosol temperature at the mouth end of an aerosol generating article varies by puff number.

Figure 1 a illustrates a schematic view of a filter element 100 for an aerosol generating article. The filter element 100 comprises a first segment 105 comprising a longitudinally extending hollow tube comprising a sheet of material; and a second segment 110 comprising a longitudinally extending core comprising a biodegradable filtering material 115. The first segment 105 is joined to the second segment 110, and the first and second segments are cylindrical.

The first segment 105 comprises three helically wound sheets of paper 107 that form the wall of the hollow paper tube, as illustrated in figure 1 b. The first segment 105 has a length of 9 mm, a circumference of 22.25 mm and a pressure drop value of zero mmWg/mm.

The first segment is made by advancing a sheet of paper in a longitudinal direction; helically winding the sheet of paper around a shaping rod, such that the sheet of paper partially overlaps with itself on successive helical turns, thereby forming a longitudinally extending hollow tube; and cutting the continuous rod to form individual segments.

The second segment 110 comprises a gathered sheet of paper filtering material 115, the sheet of paper being coated in a hydrophobic material such as oxidised starch E1404. The paper may contain the following components:

Table 1. Components of paper filtering material.

The second segment 110 has a length of 9 mm, a circumference of 22.25 mm and a pressure drop value of 2.5 mmWg/mm. The second segment 110 is made by coating a sheet of paper filtering material with a hydrophobic material such as E1404 via any of the standard coating methods known in the art; gathering one or more sheets of the coated sheet of paper filtering material into a longitudinally extending cylindrical core; and wrapping the longitudinally extending cylindrical core using one or more further sheets of paper.

The first segment 105 is abutted to the second segment 110 and is joined to the second segment 110 by a sheet of plugwrap paper 124, which has a basis weight of 27 gsm. The plugwrap paper 124 engages around the first segment 105 and the second segment 110, as further illustrated in figures 1b and 1c. The wrapped first and second segment has a length of 18 mm, a circumference of 22.55 mm, a pressure drop value of 1.5 mmWg/mm, a hardness of 93% hardness and a weight of 140 mg. During use, the first segment 105 is positioned upstream from the second segment 110.

The first and second segments may be joined together by the following method to form a filter element, the method includes advancing the first segment in a longitudinal direction; advancing the second segment in a longitudinal direction; advancing the first and second segments in an alternating and continuous array; engaging a plugwrap paper around the segments to form a continuous rod; cutting the rod to form a filter element comprising a wrapped first and second segment.

Figure 2a illustrates a schematic view of a filter element 200 for an aerosol generating article. The filter element 200 comprises a first segment 105 comprising a longitudinally extending hollow paper tube; a second segment 110 comprising a longitudinally extending core comprising a filtering material 115; and a third segment 212 comprising a longitudinally extending core of cellulose acetate filtering material. The first segment 105 and second segment 110 are as described above with respect to Figure 1.

The third segment 212 comprises a longitudinally extending cylindrical core of cellulose acetate filtering material. The third segment 212 comprises a paper outer wrapper engaged around the longitudinally extending core. The third segment has a length of 10 mm, a pressure drop value of 10.8 mmWg/mm and is cylindrical. The third segment is formed from cellulose acetate tow by methods known in the art.

Figure 2b illustrates a side profile of the filter element in 2a, showing the first segment 105 abutted to an end of the second segment 110. The other end of the second segment 110 is abutted to an end of the third segment 212. The first segment 105 and the second segment 110 are joined together by a first sheet of paper 124 which engages around the first segment 105 and the second segment 110. The third segment 212 is joined to the second segment 110 by a second sheet of paper 215, which has a weight of 27 gsm, and which engages around the first sheet of paper 124 and the third segment 212.

The first, second and third segments are joined by the steps of: advancing the first segment in a longitudinal direction, advancing the second segment in a longitudinal direction, advancing the third segment in a longitudinal direction; advancing an alternating and continuous array of first, second and third segments in a longitudinal direction; securing a first sheet of plugwrap paper around the first and second segments; securing a second sheet of plugwrap paper around the first sheet of paper and the third segment to form a continuous rod; and cutting the continuous rod to form a filter element comprising a first segment, a second segment and a third segment.

Figure 3a illustrates a schematic view of an aerosol generating article 300. The aerosol generating article 300 comprises a filter element as described in figure 2; and a fourth segment 302 comprising a longitudinally extending core comprising reconstituted tobacco. The fourth segment 302 has a length of 12 mm, a circumference of 22 mm and is cylindrical. The fourth segment 302 is positioned at the upstream end of the aerosol generating article 300. The fourth segment is made from reconstituted tobacco by methods known in the art.

Figure 3b illustrates a side profile of the filter element in Figure 3a, showing that an end of the fourth segment 302 is abutted to an end of the first segment 105. The other end of the first segment is abutted to an end of the second segment 110. The other end of the second segment 110 is abutted to an end of the third segment 212. The first segment 105 and the second segment 110 are joined by a sheet of plugwrap paper 124 which engages around the first segment 105 and the second segment 110. The second sheet of plugwrap paper 215 engages around the first sheet of plugwrap paper 124 and the third segment 212 to thereby join the second segment 110 to the third segment 212, and the second sheet of plugwrap paper 215 also engages around the fourth segment 302 to thereby join the fourth segment 302 to the first segment 105. The aerosol generating article according to figure 3, has a circumference of 22.85 mm, a length of 40 mm, a pressure drop value of 37.5 mmWg/mm and a weight of 600 mg. The fourth segment is joined to the filter element described in figure 3 by a method including advancing a fourth segment in a longitudinal direction, advancing a first segment in a longitudinal direction, advancing a second segment in a longitudinal direction, advancing a third segment in a longitudinal direction; advancing an alternating and continuous array of fourth, first, second and third segments in a longitudinal direction; engaging a first sheet of plugwrap paper around the first and second segments; engaging a second sheet of plugwrap paper around the first sheet of paper and the third segment and the fourth segment to form a continuous rod; and cutting the continuous rod to form an aerosol generating article comprising a fourth segment, a first segment, a second segment and a third segment.

During use, the aerosol generating article 300 is inserted into a device to form an aerosol generating system. Such a system includes a heat source, such as a heating element, which heats the fourth segment to thereby generate an aerosol.

During use, the user sucks on the third segment of the aerosol generating article, in order to draw aerosol towards the user. When the user sucks, aerosol is drawn from the fourth segment, where the aerosol is generated, through the first segment and the second segment to the third segment, which is positioned at the mouth end. As the aerosol passes through the filter element, the aerosol is both filtered and cooled.

Example 1

An aerosol generating article, according to figure 3, was prepared according to the method as described above, and assembled for testing.

The first segment comprises a hollow paper cylindrical tube comprising three helically wound sheets of paper that form the wall of the hollow paper tube of length 9 mm. The second segment comprises a gathered sheet of paper coated in oxidised starch E1404, and overwrapped with a plugwrap paper. The second segment has a length of 9 mm. The third segment comprises a longitudinally extending core of cellulose acetate filtering material and the fourth segment comprises reconstituted tobacco.

Comparative Example 1 An aerosol generating article was assembled including a plug of reconstituted tobacco, a hollow acetate tube, a polylactic acid (PLA) cooling element and a cylindrical plug of cellulose acetate tow in an analogous arrangement to that shown in Figure 3.

Comparative Example 2

An aerosol generating article was assembled including a plug of reconstituted tobacco, a hollow acetate tube, a paper filter element and a cylindrical plug of cellulose acetate tow in an analogous arrangement to that shown in figure 4. The compositions of each aerosol generating article are detailed in table 2.

Table 2. The segments in each aerosol generating articles.

Example 3

The aerosol generating article according to the Example 1 , Comparative Example 1 and Comparative Example 2 were tested in the same heated tobacco product system.

Each aerosol generating article was combined with a heat source to form an aerosol generating system (heated tobacco product). The mouth end of the aerosol generating article was inserted into a smoking machine which was configured to withdraw aerosol from the heated tobacco product. An infrared camera was used to analyse the temperature of the aerosol at the mouth end of the heated tobacco product during the test. The smoking machine was configured to withdraw aerosol (i.e. take a puff) from the heated tobacco product every 30 seconds, each puff being 2 seconds long. The temperature of the aerosol at the mouth end of the heated tobacco product was measured during each puff. The experiment was performed at standard room temperature and humidity. The experiment was repeated for each aerosol generating article of Example 1 , Comparative Example 1 and Comparative Example 2.

Table 3. Table of experimental conditions.

Figure 4 illustrates the temperature of the aerosol at the mouth end during each puff for the aerosol generating article of Example 1 , Comparative Example 1 and Comparative Example 2. The figure shows that the combination of a hollow paper tube with a segment comprising a filtering material comprising a biodegradable material, results in aerosol cooling that is more stable than for the aerosol generating articles in comparative examples 1 and 2. As shown in figure 4, the temperature at the mouth end between puffs 2 to 12 for the aerosol generating article of example 1 , reduces at a slower rate than for comparative example 1. Notably, the temperature at the mouth end between puffs 8 to 12 for the aerosol generating article of example 1 , shows a minimal temperature decrease (~0°C), whereas the temperature at the mouth end between puffs 8 to 12 for comparative example 1 and comparative example 2 show a greater temperature decrease. These results demonstrate that the filter element of example 1 leads to greater stability in the aerosol temperature profile. As seen in table 4, the change in temperature between puffs 1 to 12 is considerably smaller (~4.9°C), for the aerosol generating article of example 1 , compared to comparative examples 1 (~12.6°C) and 2 (~11.2°C). These results show that the aerosol generating article of example 1 demonstrates a less significant temperature drop throughout its use, than comparative examples 1 and 2.

Table 4. Temperature change between puffs 1 and 12.

Claims

1. A filter element for an aerosol generating article comprising: a first segment comprising a longitudinally extending hollow tube comprising a sheet of material; a second segment comprising a longitudinally extending core comprising a filtering material; wherein the first segment is joined to the second segment; and wherein the filtering material comprises a biodegradable material.

2. The filter element according to claim 1 , wherein the sheet of material comprises one or more of, hemp, lyocell, flax, cotton, sisal, jute, abaca, cotton, coconut fibres, bamboo fibres or starch.

3. The filter element according to any preceding claim, wherein the sheet of material is paper.

4. The filter element according to any preceding claim, wherein the first segment does not comprise cellulose acetate.

5. The filter element according to any preceding claim, wherein the second segment comprises a gathered sheet of biodegradable material.

6. The filter element according to any preceding claim, wherein the biodegradable material is paper.

7. The filter element according to any preceding claim, wherein the filtering material further comprises a hydrophobic material.

8. The filter element according to any preceding claim, wherein the hollow tube comprises one or more helically wound sheet of material.

9. The filter element according to any preceding claim, wherein the first segment has a pressure drop value of from zero mmWg/mm to 1 mmWg/mm.

10. The filter element according to any preceding claim, wherein the second segment has a pressure drop value of from 1.25 mmWg/mm to 10 mmWg/mm.

11. The filter element according to any preceding claim, wherein the difference in pressure drop value between the first segment and the second segment is from 0.25 mmWg/mm to 10 mmWg/mm.

12. The filter element according to any preceding claim, wherein, in use, the first segment is positioned upstream from the second segment.

13. The filter element according to any preceding claim wherein the first segment and the second segment are joined together by a sheet of paper which engages around the first segment and the second segment.

14. The filter element according to any preceding claim, wherein the hardness of the filter element is from 85% hardness to 95% hardness.

15. The filter element according to any preceding claim, comprising a third segment; wherein the third segment comprises a longitudinally extending core comprising filtering material; and wherein the third segment is joined to the second segment.

16. The filter element according to claim 15 wherein, in use, the first segment is positioned upstream from the second segment, and the third segment is positioned downstream from the second segment.

17. The filter element according to claim 15 or 16, wherein the first segment and the second segment are joined together by a first sheet of paper which engages around the first segment and the second segment; and wherein the third segment is joined to the second segment by a second sheet of paper which engages around the first sheet of paper and the third segment.

18. An aerosol generating article comprising: a filter element according to any one of claims 1 to 17, and a fourth segment comprising a longitudinally extending core comprising an aerosol generating substance; wherein the fourth segment is joined to the first segment.

19. The aerosol generating article according to claim 18, wherein, the first segment and the second segment are joined together by a first sheet of paper which engages around the first segment and the second segment; wherein the third segment is joined to the second segment by a second sheet of paper and the fourth segment is joined to the first segment by the second sheet of paper; wherein the second sheet of paper engages around the first sheet of paper and the third and fourth segments.

20. The aerosol generating system comprising an aerosol generating article according to claim 19 and a heat source.

21. A method for making a filter element for an aerosol generating article comprising the steps of: advancing a first segment in a longitudinal direction; advancing a second segment in a longitudinal direction; engaging a first sheet of paper around the first and second segments; wherein the first segment comprises a longitudinally extending hollow tube comprising a sheet of material; wherein the second segment comprises a longitudinally extending core comprising a filtering material; and wherein the filtering material comprises a biodegradable material.

22. The method for making a filter element according to claim 21 comprising steps of: advancing a third segment in a longitudinal direction; and engaging a second sheet of paper around the first sheet of paper and the third segment; wherein the third segment comprises a filtering material.

23. The method for making an aerosol generating article according to claim 22 comprising steps of: advancing a fourth segment in a longitudinal direction; and engaging the second sheet of paper around the first sheet of paper and the fourth segment and the third segment; wherein the fourth segment comprises an aerosol generating substance.