EP4525644A1

EP4525644A1 - An aerosol generating article

Info

Publication number: EP4525644A1
Application number: EP23728285.0A
Authority: EP
Inventors: Pier Paolo MONTICONE; Layth Sliman BOUCHUIGUIR
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2022-05-20
Filing date: 2023-05-17
Publication date: 2025-03-26
Also published as: US20250318575A1; CN119212577A; KR20250012547A; JP2025516842A; WO2023222763A1

Abstract

An aerosol generating article (10) for an aerosol generating device (18). The aerosol generating article (10) comprises an aerosol generating substrate (12) and a filter (14) circumscribed by a wrapper (16). The filter (14) comprises a thermochromic material and a flavouring, wherein Only the tip (62) of the filter comprises the thermochromic material. The thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the tip (62) of the filter (14).

Description

AN AEROSOL GENERATING ARTICLE

Technical Field

The present disclosure relates generally to an aerosol generating article, and more particularly to an aerosol generating article for an aerosol generating device.

Technical Background

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in recent years as an alternative to the use of traditional tobacco products. Various devices and systems are available that heat or warm, rather than bum, an aerosol generating substrate to generate an aerosol for inhalation by a user.

A commonly available reduced-risk or modified-risk device is an aerosol generating device, or so-called heat-not-bum device. Devices of this type generate an aerosol or vapour by heating an aerosol generating substrate, for instance comprised in an aerosol generating article such as a heated tobacco stick, to a temperature typically in the range 150°C to 300°C, in a heating compartment. Heating the aerosol generating substrate to a temperature within this range, without burning or combusting the aerosol generating substrate, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device.

Typically, used aerosol generating articles for disposal are stored by a user with new unused aerosol generating articles until an opportunity for disposal arises. A user must therefore distinguish between new and used aerosol generating articles. In prior art arrangements, this can be difficult in view of the similarity in appearance of new and used aerosol generating articles. If a user, by error, attempts to vape a used aerosol generating article they will have a negative sensorial experience, and possibly have increased health risks. Furthermore, battery power will be wasted, such that the device may require recharging before the next vaping session. There is, therefore, a need to provide aerosol generating articles which mitigate this drawback.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided an aerosol generating article for an aerosol generating device, wherein the aerosol generating article comprises an aerosol generating substrate and a filter circumscribed by a wrapper, wherein at least a portion of the filter comprises a thermochromic material and a flavouring, wherein the thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the at least a portion of the filter. The filter preferably comprises a tip, and the thermochromic material is preferably comprised in the tip of the filter, and most preferably comprised only in the tip of the filter.

A user can readily distinguish between new and used aerosol generating articles based on the colour change of the at least a portion of the filter. A user is therefore considerably less likely to erroneously select a used aerosol generating article for vaping, for instance when new and used aerosol generating articles 10 are stored together, and thus experience the associated negative sensorial experience, health risks and wasted battery usage. The used aerosol generating articles also have an aesthetically pleasing appearance based on the colour change. When the thermochromic material is comprised in the tip of the filter, the colour change or absence thereof may be easily visible to the user when the aerosol generating articles are stored on end in a packet, assisting the user in distinguishing between new and used aerosol generating articles without the need to first extract the articles from the packet. Providing the thermochromic material only in the tip of the filter may reduce material usage, and may also provide an aesthetically pleasing surprise for the user following use of the aerosol generating article.

Below the threshold temperature the colour of the at least a portion of the filter may be determined by the thermochromic material. Below the threshold temperature the colour of the at least a portion of the filter may be indicative of the identity of the flavouring. This provides a clear visual indication of the flavouring present.

The thermochromic material and/or flavouring may be impregnated into the material of the at least a portion of the filter 14, e.g. into the material of the tip of the filter. The thermochromic material and/or flavouring may be evenly dispersed throughout the at least a portion of the filter. Alternatively, the concentration of thermochromic material and/or flavouring comprised in the at least a portion of the filter may vary at different locations. The thermochromic material and/or flavouring may be comprised in the at least aportion of the filter only at selected isolated locations. The thermochromic material and/or flavouring may be comprised in a portion only of the filter, e.g. only in the tip of the filter. This can reduce materials used and thus costs. Alternatively, the thermochromic material and/or flavouring may be comprised in the whole of the filter. This can be visually more striking.

Possibly, the threshold temperature is from 50°C to 250°C, or from 100°C to 250°C.

The thermochromic material may comprise any of: copper (I) iodide (Cui), 2Cu(CNS)2.2pyridine, or ammonium metavanadate (NH4VO3).

Possibly, the thermochromic material and the flavouring are comprised in a solution and wherein the at least a portion of the filter comprises the solution.

According to a second aspect of the present disclosure, there is provided a method of manufacturing an aerosol generating article for an aerosol generating device, wherein the aerosol generating article comprises an aerosol generating substrate and a filter circumscribed by a wrapper, wherein the method comprises: incorporating a thermochromic material and a flavouring in at least a portion of the filter, wherein the thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the at least a portion of the filter.

Preferably the filter comprises a tip, and the thermochromic material is incorporated only in the tip of the filter.

Possibly, the thermochromic material and flavouring is comprised in a solution, wherein the method comprises: applying the solution to the at least a portion of the filter, for example to the tip of the filter.

Possibly, the thermochromic material and flavouring is comprised in a solution, wherein the method comprises: dipping the tip of the filter in the solution. Possibly, the solution comprises a carrier solvent, wherein the method comprises: evaporating at least some of the carrier solvent during manufacture of the aerosol generating article.

Brief Description of the Drawings

Figure 1 is a diagrammatic cross-sectional view of an aerosol generating article according to examples of the disclosure; and

Figure 2 is a diagrammatic cross-sectional view of an aerosol generating device in use with an aerosol generating article according to examples of the disclosure.

Detailed Description of Embodiments

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring to Figure 1, there is shown diagrammatically an aerosol generating article 10 according to the present disclosure. The aerosol generating article 10 is configured to be used with an aerosol generating device 18, for instance as shown diagrammatically in Figure 2. The aerosol generating article 10 and the aerosol generating device 18 together form an aerosol generating system 100.

The aerosol generating device 18 may equally be referred to as a “heated tobacco device”, a “heat-not-bum tobacco device”, a “device for vaporising tobacco products”, and the like, with this being interpreted as a device suitable for achieving these effects. The features disclosed herein are equally applicable to devices which are designed to vaporise any aerosol generating substrate.

The aerosol generating device 18 is a hand-held, portable, device, by which it is meant that a user is able to hold and support the device unaided, in a single hand. The aerosol generating device 18 has a first (or proximal) end 20 and a second (or distal) end 22 and comprises a device housing 24.

The aerosol generating device 18 includes a controller 26. The aerosol generating device 18 may include a user interface for controlling the operation of the aerosol generating device 18 via the controller 26. The controller 26 is configured to detect the initiation of use of the aerosol generating device 18, for example, in response to a user input, such as a button press to activate the aerosol generating device 18, or in response to a detected airflow through the aerosol generating device 18. As will be understood by one of ordinary skill in the art, an airflow through the aerosol generating device 18 is indicative of a user inhalation or ‘puff. The aerosol generating device 18 may, for example, include a puff detector, such as an airflow sensor (not shown), to detect an airflow through the aerosol generating device 18.

The controller 26 includes electronic circuitry. The aerosol generating device 18 includes a power source 28, such as a battery. The power source 28 and the electronic circuitiy may be configured to operate at a high frequency in the case of an inductively heated vapour generating device 18. For example, the power source 28 and the electronic circuitiy may be configured to operate at a frequency of between approximately 80 kHz and 500 kHz, possibly between approximately 150 kHz and 250 kHz, and possibly at approximately 200 kHz. The power source 28 and the electronic circuitry could be configured to operate at a higher frequency, for example in the MHz range, if required.

The aerosol generating device 18 comprises a heating assembly 30. The heating assembly 30 further comprises a heating compartment 32. The heating compartment 32 is arranged to receive an aerosol generating article 10 according to examples of the present disclosure. In some examples, the heating compartment 32 has a substantially cylindrical cross-section. The heating compartment 32 defines a cavity.

The heating compartment 32 has a first end 34 and a second end 36. The heating compartment 32 includes an opening 38 at the first end 34 for receiving an aerosol generating article 10. In the illustrated example, the heating compartment 32 includes a substantially cylindrical side wall 40, i.e., a side wall 40 which has a substantially circular cross-section.

The aerosol generating article 10 according to examples of the disclosure comprises an aerosol generating substrate 12. The aerosol generating substrate 12 may be any type of solid or semisolid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut leaves, cut filler, porous material, foam material or sheets. The aerosol generating substrate 12 may comprise plant derived material and in particular, may comprise tobacco. It may advantageously comprise reconstituted tobacco. The aerosol generating substrate 12 may be a tobacco plug.

The aerosol generating substrate 12 may comprise an aerosol -former. Examples of aerosolformers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the aerosol generating substrate 12 may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some example, the aerosol generating substrate 12 may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis.

Upon heating, the aerosol generating substrate 12 may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.

Typically, the shape of the aerosol generating article 10 corresponds to the shape of the heating compartment 32. The aerosol generating article 10 may be generally cylindrical or rod-shaped. The aerosol generating article 10 may be formed substantially in the shape of a stick, and may broadly resemble a cigarette, having a tubular region with the aerosol generating substrate 12 arranged in a suitable manner. The aerosol generating article 10 may be a disposable and replaceable article which may, for example, contain tobacco as the aerosol generating substrate. The aerosol generating article 10 may be a heated tobacco stick. The aerosol generating article 10 is a consumable.

The aerosol generating article 10 has a first end 42 (or mouth end), a second end 44, and comprises a filter 14 at the first end 42. The filter 14 acts as a mouthpiece and may compnse an air-permeable plug, for example comprising cellulose acetate fibres.

In illustrated example, the aerosol generating article 10 comprises a first section 46, a second section 48, and a third section 49. The first section 46 comprises the aerosol generating substrate 12, i.e., a tobacco plug. In the illustrated example, the full extent of the first section 46 is not shown. The second section 48 includes a vapour outlet channel 50. The vapour outlet channel 50 comprises a hollow tube 52, for instance, an acetate tube. The third section 49 includes the filter 14. In the illustrated example, the filter 14 comprises a mouthpiece filter 54 and a polymer-film filter 56. The aerosol generating substrate 12 and filter 14 are circumscribed by a wrapper 16, which in examples of the disclosure is a paper wrapper 16, and are thus embodied as an aerosol generating article 10. In the illustrated example, a secondary paper wrapper 58, i.e., a mouthend paper, is provided at the first end 42. The wrapper 16 may be permeable. The wrapper 16 is an outer wrapper. One or more vapour collection regions, cooling regions, and other structure may also be included in some designs.

To use the aerosol generating device 18, a user inserts an aerosol generating article 10 through the opening 38 into the heating compartment 32, so that the second end 44 of the aerosol generating article 10 is positioned at the second end 36 of the heating compartment 32 and so that the filter 14 at the first end 42 of the aerosol generating article 10 projects from the first end 34 of the heating compartment 32 to permit engagement by a user’s lips.

The heating assembly 30 comprises a heater 60, i.e., a heating element, arranged to heat the aerosol generating substrate 12 of an aerosol generating article 10 received in the heating compartment 32.

The heating assembly 30 may be an induction heating assembly (not shown). The induction heating assembly further comprises an induction coil (not shown). The induction coil is arranged to be energised to generate an alternating electromagnetic field for inductively heating an induction heatable susceptor (not shown). Accordingly, in such examples the heater 60 is an induction heatable susceptor.

The induction heatable susceptor may be arranged around the periphery of the heating compartment 32. Alternatively, the induction heatable susceptor may be arranged to project into the heating compartment 32 from the second end 36 (e.g., as a heating blade or pin) to penetrate the aerosol generating substrate 12 when the aerosol generating article 10 is inserted into the aerosol generating device 18. In other examples, the induction heatable susceptor is instead provided in the aerosol generating substrate 12 during manufacture of the aerosol generating article 10. In such examples, the aerosol generating article 10 comprises the induction heatable susceptor. The induction coil can be energised by the power source 28 and controller 26. The induction coil may comprise a Litz wire or a Litz cable. It will, however, be understood that other materials could be used.

The induction coil may extend around the heating compartment 32. Accordingly, the induction coil may be annular. The induction coil may be substantially helical in shape. In some examples, the circular cross-section of a helical induction coil may facilitate the insertion of an aerosol generating article 10 and optionally one or more induction heatable susceptors, into the heating compartment 32 and ensure uniform heating of the aerosol generating substrate 12.

The induction heatable susceptor comprises an electrically conductive material. The induction heatable susceptor may comprise one or more, but not limited to, of graphite, molybdenum, silicon carbide, niobium, aluminium, iron, nickel, nickel containing compounds, titanium, mild steel, stainless steel, low carbon steel and alloys thereof, e.g., nickel chromium or nickel copper, and composites of metallic materials. In some examples, the induction heatable susceptor comprises a metal selected from the group consisting of mild steel, stainless steel, and low carbon stainless steel.

In use, with the application of an electromagnetic field in its vicinity, the induction heatable susceptor(s) generate heat due to eddy currents and magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat.

The induction coil may be arranged to operate in use with a fluctuating electromagnetic field having a magnetic flux density of between approximately 20mT and approximately 2.0T at the point of highest concentration.

An alternative approach is to employ a resistive heating assembly (not shown). In such cases, the heater 60 is a resistive heater (not shown). The resistive heater may surround the aerosol generating substrate 12 and transfer heat to an outer surface of the aerosol generating substrate 12, for instance, the resistive heater may be arranged around the periphery of the heating compartment 32. Alternatively, the resistive heater may be arranged to proj ect into the heating compartment 32 from the second end 36 (e.g. , as a heating blade or pin) to penetrate the aerosol generating substrate 12 when the aerosol generating article 10 is inserted into the aerosol generating device 18. In use, current from the power supply 28 is supplied directly to the resistive heater to generate heat.

In examples of the disclosure, at least a portion of the filter 14 of the aerosol generating article 10 comprises a thermochromic material and a flavouring. The thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the at least a portion of the filter 14. The colour change of the at least a portion of the filter 14 is therefore permanent. The colour change is a visual change, i.e., results in a change in the appearance of the at least a portion of the filter 14.

A user can readily distinguish between new and used aerosol generating articles 10 based on the colour change of the at least a portion of the filter 14. A user is therefore considerably less likely to erroneously select a used aerosol generating article 10 for vaping, for instance when new and used aerosol generating articles 10 are stored together, and thus experience the associated negative sensorial experience, health risks and wasted battery usage. The used aerosol generating articles also have an aesthetically pleasing appearance based on the colour change.

In some examples, the threshold temperature is from 50°C to 250°C. The threshold temperature may be from 50°C to 200°C. The threshold temperature may be from 50°C to 300°C. The threshold temperature may be from 150°C to 300°C. The threshold temperature may be from 150°C to 250°C, or from 100°C to 250°C. The threshold temperature may be from 60°C to 220°C. The threshold temperature may be less than 300°C, and may be less than 250°C, and may be less than 200°C. The threshold temperature may be at least 50°C, and may be at least 100°C. The threshold temperature is greater than a maximum storage temperature of aerosol generating articles 10 and may be lower than a minimum vaping temperature. In examples of the disclosure, the thermochromic material undergoes a temperature dependent irreversible colour change when vapour at or above the threshold temperature passes through the filter 14 and encounters, i.e., traverses, the thermochromic material. Accordingly, it is the vapour temperature which determines whether or not the threshold temperature is met.

The thermochromic material may comprise, for example, copper (I) iodide (Cui), 2Cu(CNS)2.2pyridine, or ammonium metavanadate (NH4VO3). At or above a transition temperature of 60°C to 62°C, copper (I) iodide causes a colour change from grey tan to orange. At or above a transition temperature of 135°C, 2Cu(CNS)2.2pyridine causes a colour change from green to yellow. At or above a transition temperature of 220°C, 2Cu(CNS)2.2pyridine causes a colour change from yellow to black. At or above a transition temperature of 150°C, ammonium metavanadate causes a colour change from white to brown. At or above a transition temperature of 170°C, ammonium metavanadate causes a colour change from brown to black.

In some examples, the thermochromic material may comprise a number of different discrete chemical compounds, for instance, more than one of copper (I) iodide (Cui), 2Cu(CNS)2.2pyridine, or ammonium metavanadate (NH4VO3).

The thermochromic material may be a dye, or may be comprised in a dye formulation. The thermochromic material may be an ink, or comprised in an ink formulation.

A flavouring also known as a flavour, flavouring agent or flavourant is any substance that gives another substance taste. The flavouring may be a volatile flavour-generating component. The flavouring may be provided in solid or liquid form. The flavouring may include, but is not limited to, any of the following: menthol or menthol-like substances, liquorice, chocolate, fruit flavour or essence (e g., citrus, cherry, etc.), vanilla, spice (e.g., ginger, cinnamon), and tobacco flavour. In some examples the flavouring also provides a fragrance.

In some examples, the thermochromic material and/or flavouring is comprised in a portion only of the filter 14. In such examples, the thermochromic material causes a colour change of a portion only of the filter 14. This can reduce materials used and thus costs. In some examples, the portion only of the filter 14 may be a minority of the filter 14, for example less than half of the filter 14. For instance, in some examples the portion only of the filter may be the tip 62 of the filter. In other examples, the portion only of the filter 14 may be most of, i.e., the majority of, the filter 14.

Alternatively, the thermochromic material and/or flavouring may be comprised in the whole of the filter 14. In such examples, the thermochromic material causes a colour change of the whole of the filter 14. This can be visually more striking. In some examples, the thermochromic material and flavouring are comprised in the same location in the at least a portion of the filter 14. In other examples, the thermochromic material and flavouring are comprised in different locations in the at least a portion of the filter 14.

In examples wherein the filter 14 comprises a mouthpiece filter 54 and a polymer-film filter 56, the thermochromic material and flavouring may be comprised in the mouthpiece filter 54 and/or the polymer-film filter 56. In other examples, the thermochromic material may be comprised in a one of the mouthpiece filter 54 or the polymer-film filter 56 and the flavouring may be comprised in the other of the mouthpiece filter 54 or the polymer-film filter 56. The thermochromic material and/or flavouring may be comprised in a portion only, or in the whole of, the mouthpiece filter 54 and/or the polymer-film filter 56.

Below the threshold temperature, the thermochromic material may impart a colour on the at least a portion of the filter 14 which is different from the natural colour of the filter material. Accordingly, the colour of the at least a portion of the filter 14 may be determined by the thermochromic material. In such examples, the colour imparted on the at least a portion of the filter 14 by the thermochromic material above the threshold temperature may be the same, or substantially the same, as the natural colour of the filter material. Alternatively, the colour imparted on the at least a portion of the filter 14 by the thermochromic material above the threshold temperature may be different from the natural colour of the filter material but also different from the colour impartment on the at least a portion of the filter 14 by the thermochromic material below the threshold temperature.

In other examples, below the threshold temperature the thermochromic material may impart a colour on the at least a portion of the filter 14 which is the same, or substantially the same, as the natural colour of the filter material. In such examples, the colour imparted on the at least a portion of the filter 14 by the thermochromic material above the threshold temperature is different from the natural colour of the filter material.

In some examples, below the threshold temperature the thermochromic material does not impart any colour on the at least a portion of the filter 14. The thermochromic material is thus colourless. Accordingly, below the threshold temperature the filter comprising thermochromic material retains the natural colour of the filter material. In some examples, below the threshold temperature the colour of the at least a portion of the filter 14 is indicative of the identity of the flavouring, for instance, green for menthol and red for berries. This provides a clear visual indication of the flavouring present. As described above, the colour of the at least a portion of the filter 14 below the threshold temperature may be determined by the thermochromic material or may be the natural colour of the filter material. Alternatively, the colour of the at least a portion of the filter 14 below the threshold temperature may be determined by the presence of a dye, for example.

In other examples, at or above the threshold temperature the colour of the at least a portion of the filter 14 may be indicative of the identity of the flavouring, for instance, green for menthol and red for berries. As described above, the colour of the at least a portion of the filter 14 at or above the threshold temperature is caused by the temperature dependent irreversible colour change of the thermochromic material.

In some examples, the thermochromic material and/or flavouring is impregnated into the material of the at least a portion of the filter 14. Accordingly, the thermochromic material and/or flavouring is integral to the at least a portion of the filter 14. The thermochromic material and/or flavouring is integrated into the material of the at least a portion of the filter 14. The thermochromic material and/or flavouring is associated with the material of the at least a portion of the filter 14. The thermochromic material and/or flavouring is incorporated into the material of the at least a portion of the filter 14.

The thermochromic material and/or flavouring may be evenly dispersed throughout the at least a portion of the filter 14. Alternatively, in some examples the concentration of thermochromic material and/or flavouring comprised in the at least a portion of the filter 14 varies a different locations. For example, the thermochromic material and/or flavouring may be concentrated on or around the visible front part of the filter 14, i. e. , the filter tip 62. The thermochromic material and/or flavouring may be comprised in the at least a portion of the filter 14 only at selected isolated locations.

The thermochromic material and the flavouring may be comprised in a solution. Accordingly, in such examples the thermochromic material is mixed with the flavouring. The at least a portion of the filter 14 may comprise the solution. In some examples, the solution is impregnated into the material of the at least a portion of the filter 14. Accordingly, the solution is integral to the at least a portion of the filter 14. The solution is integrated into the material of the at least a portion of the filter 14. The solution is associated with the material of the at least a portion of the filter 14. The solution is incorporated into the material of the at least a portion of the filter 14.

The solution may comprise one or more further components, i.e., ingredients, for instance that increase or improve the savouriness/flavourings. Such further components include, but are not limited to, the following substances: sugar or sugar-like substances, oils, alcohols, or fragrances.

In use of the aerosol generating system 100, heat from the heater 60 (i.e., induction heatable susceptor or resistive heater) is transferred to the aerosol generating substrate 12 of an aerosol generating article 10 positioned in the heating compartment 32, for example by conduction, radiation and convection, to heat the aerosol generating substrate 12 (without burning the aerosol generating substrate 12) and thereby generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the aerosol generating device 18 through the filter 14. As vapour/aerosol at or above the threshold temperature passes through the filter 14, the thermochromic material undergoes a temperature dependent irreversible colour change causing a colour change of the at least a portion of the filter 14 comprising the thermochromic material. Flavouring present in the at least a portion of the filter 14 imparts a flavour to the vapour/aerosol as it passes through the filter 14. The vaporisation of the aerosol generating substrate 12 is facilitated by the addition of air from the surrounding environment, e.g., through an air inlet (not shown).

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

Examples of the disclosure also provide a method of manufacturing an aerosol generating article 10 according to examples of the disclosure. The method comprises incorporating the thermochromic material and flavouring in the at least a portion of the filter 14. As described above, in some examples the thermochromic material and flavouring is comprised in a solution. In such examples, the thermochromic material is mixed with the flavouring. The solution may be in the form of a liquid, oil, or wax. In such examples, the method comprises applying the solution to the at least a portion of the filter 14. The solution may be impregnated into the material of the at least a portion of the filter 14. The solution may be applied leveraging the capillary forces of the filter 14, e.g., dipping or applying the solution on the tip 62 of the filter 14. Alternatively, the solution could be dispersed into the material of the filter 14 (i.e., filter material), e.g., by spraying the filter material before forming the cylindrical shape of the filter 14.

The solution may comprise a carrier solvent. In such examples, the method may comprise evaporating at least some of the carrier solvent during manufacture of the aerosol generating article 10. The carrier solvent may be partially or entirely evaporated during manufacture, i.e., before use. In the case of a liquid solution, the carrier solvent may be aqueous or non-aqueous.

In some examples, if it is desired to reduce the evaporation of a earner solvent, humectants may be added to, or used as, a carrier solvent. Suitable humectants include, but are not limited to, the following: polyhydric alcohols (e.g., propylene glycol (PG), triethylene glycol, 1,2- butanediol, and vegetable glycerine (VG)) and their esters (e.g., glycerol mono-, di- or triacetate).

Before any evaporation of carrier solvent, a typical solution volume is in the range of from 0.1 ml to 1.0 ml, and in particular the solution volume may be 0.3 ml. Typically, the thermochromic material may be less than 10% of the liquid volume, and the dry volume of the solution would typically be less than 50% of the liquid volume.

The Figures also illustrate a method of manufacturing an aerosol generating device 10 according to examples of the disclosure. The Figures also illustrate a method of providing an aerosol generating system 100 according to examples of the disclosure.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

Claims

1. An aerosol generating article (10) for an aerosol generating device (18), wherein the aerosol generating article (10) comprises an aerosol generating substrate (12) and a filter (14) circumscribed by a wrapper (16), the filter (14) comprising a tip (62), wherein the filter (14) comprises a thermochromic material and a flavouring, the thermochromic material being compnsed only in the tip (62) of the filter, wherein the thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the tip (62) of the filter (14).

2. An aerosol generating article (10) according to claim 1, wherein below the threshold temperature the thermochromic material imparts a colour on the tip (62) of the filter (14) which is different from the natural colour of the filter material.

3. An aerosol generating article (10) according to claims 1 or 2, wherein below the threshold temperature the colour of the tip (62) of the filter (14) is indicative of the identity of the flavouring.

4. An aerosol generating article (10) according to any of the preceding claims, wherein the thermochromic material and/or flavouring is impregnated into the material of the tip (62) of the filter 14.

5. An aerosol generating article (10) according to any of the preceding claims, wherein the thermochromic material and/or flavouring is evenly dispersed throughout the tip (62) of the filter (14).

6. An aerosol generating article (10) according to any of claims 1 to 4, wherein the concentration of thermochromic material and/or flavouring comprised in the tip (62) of the filter (14) varies a different locations, or is comprised in the at least a portion of the filter (14) only at selected isolated locations.

7. An aerosol generating article (10) according to any of the preceding claims, wherein the flavouring is comprised in a portion only of the filter (14), the portion preferably being the tip (62) of the filter.

8. An aerosol generating article (10) according to any of claims 1 to 6, wherein the flavouring is comprised in the whole of the filter (14).

9. An aerosol generating article (10) according to any of the preceding claims, wherein the threshold temperature is from 50°C to 250°C.

10. An aerosol generating article (10) according to any of the preceding claims, wherein the thermochromic material comprises any of: copper (I) iodide (Cui), 2Cu(CNS)2.2pyridine, or ammonium metavanadate (NH4VO3).

11. An aerosol generating article (10) according to any of the preceding claims, wherein the thermochromic material and the flavouring are comprised in a solution and wherein the tip (62) of the filter (14) comprises the solution.

12. A method of manufacturing an aerosol generating article (10) for an aerosol generating device (18), wherein the aerosol generating article (10) comprises an aerosol generating substrate (12) and a filter (14) circumscribed by a wrapper (16), the filter (14) comprising a tip (62), wherein the method comprises: incorporating a thermochromic material and a flavouring in the filter (14), the thermochromic material being incorporated only in the tip (62) of the filter, wherein the thermochromic material is capable of undergoing a temperature dependent irreversible colour change at or above a threshold temperature to cause a colour change of the tip (62) of the filter (14).

13. A method according to claim 12, wherein the thermochromic material and flavouring is comprised in a solution, wherein the method comprises: applying the solution to the tip (62) of the filter (14).

14. A method according to claim 12 or claim 13, wherein the thermochromic material and flavouring is comprised in a solution, wherein the method comprises: dipping the tip (62) of the filter in the solution.

15. A method according to claim 13 or claim 14, wherein the solution comprises a carrier solvent, wherein the method comprises: evaporating at least some of the carrier solvent during manufacture of the aerosol generating article (10).