An aerosol-generating article and a method of manufacturing the same

Abstract

There is provided an aerosol-generating article (100) comprising a filter portion (110) comprising a filter material; an aerosol-generating portion (120) comprising an aerosol-generating material; a wrapper (140) connecting the filter portion (110) and the aerosol-generating portion (120); and a visual indicator disposed on the wrapper (140) and configured to provide visual feedback when a property of the aerosol-generating article (100) or an aerosol flowing through the filter portion (110) meets a first threshold, said property influencing a temperature of the filter portion (110) and said aerosol being generated upon heating of the aerosol- generating material. There is also provided a method (500) of manufacturing the aerosol-generating article (100) comprising: providing (502) a filter portion (110) and an aerosol-generating portion (120); connecting (504) the filter portion (110) and the aerosol-generating portion (120) with a wrapper (140); and disposing (506) a visual indicator on the wrapper.

Description

[0001] AN AEROSOL-GENERATING ARTICLE AND A METHOD OF MANUFACTURING THE SAME

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an aerosol-generating article and a method of manufacturing the same.

[0004] BACKGROUND

[0005] 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 portion to generate an aerosol for inhalation by a user.

[0006] A commonly available reduced-risk or modified-risk device is an aerosolgenerating device, or so-called heat-not-burn (HnB) device. To generate an aerosol, a consumable, also called a heated stick, is inserted into the HnB device and is then heated up. These consumables typically comprise a filter portion, an aerosol-generating portion, and a wrapper surrounding the filter portion and the aerosol-generating portion. Devices of this type generate an aerosol or vapour by heating an aerosol-generating portion, for instance comprised in an aerosolgenerating article such as a heated stick, to a temperature typically in the range 150°C to 500°C, in a heating compartment. Heating the aerosol-generating portion to a temperature within this range, without burning or combusting the aerosol-generating portion, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device.

[0007] During the initial phase of use, the temperature of the vapour or aerosol present in the device may exceed safe levels. This increase in temperature is often due to the generation of hot water vapour from moisture present in the aerosolgenerating portion, as water has a lower boiling point than other materials present in the aerosol-generating portion, for example glycerol or propylene glycol (PG). Water vapour also has a higher specific heat capacity than PG, allowing it to carry more energy. This energy is absorbed by the filter portion, causing it to heat up along with a portion of the surrounding wrapper. As a result, when this heated wrapper comes into contact with the user’s lips during inhalation, the user may experience a high temperature sensation.

[0008] The present invention seeks to overcome the above problem.

[0009] SUMMARY OF INVENTION

[0010] According to a first aspect of the present invention, there is provided an aerosolgenerating article comprising: a filter portion comprising a filter material; an aerosol-generating portion comprising an aerosol-generating material; a wrapper connecting the filter portion and the aerosol-generating portion; and a visual indicator disposed on the wrapper and configured to provide visual feedback when a property of the aerosol-generating article or an aerosol flowing through the filter portion meets a first threshold, said property influencing a temperature of the filter portion and said aerosol being generated upon heating of the aerosol-generating material.

[0011] In the context of the present invention, the term “property” may refer to an attribute or characteristic of the aerosol-generating article (or any component of the aerosol-generating article) or the aerosol flowing through the filter portion during an inhalation of the aerosol by a user (often referred to as a “puff’). For example, the property may be a temperature or a moisture of the aerosol-generating article or of the aerosol flowing through the filter portion. More particularly, the property could be a temperature or moisture of one or more of the components of the aerosol-generating article, such as the filter portion and / or the aerosol-generating portion. Of these, it may be preferable that the property is a temperature or moisture of the filter portion because it is the filter portion that heats up the portion of the surrounding wrapper that comes into contact with the user’s lips during inhalation.

[0012] The property influences the temperature of the filter portion in that a change in the property causes a corresponding change in the temperature of the filter portion. In the context of the present invention, the aerosol generated upon heating of the aerosol-generating material may include any aerosol or vapour generated as a direct consequence of heating the aerosol-generating material. Accordingly, the aerosol generated upon heating of the aerosol-generating material may include water, nicotine, and other chemicals such as for example glycerol or PG. The property may therefore influence a temperature of the filter portion, and by extension, a temperature of the surrounding wrapper that comes into contact with the user’s lips when the user takes a puff of the aerosol-generating article.

[0013] The visual indicator may provide a means for indicating to the user, via visual feedback, when the property reaches the first threshold. This may be achieved by a chemical reaction by the visual indicator. For example, the visual indicator may comprise a material that changes colour when the property reaches the first threshold. The first threshold may correspond to a level at which the property influences the temperature of the filter portion to a level that is considered undesirable for use of the aerosol-generating article by the user. In the context of the present invention, “use” may refer to an action in which the user takes a puff or a drag from the aerosol-generating article. Thus, the visual indicator may advantageously indicate, to the user, that the temperature of the filter portion is at a level which would cause the user to experience a high temperature sensation when their lips come into contact with the wrapper surrounding the filter portion.

[0014] Since the visual indicator is disposed on the wrapper, the visual feedback may be clearly visible to the user during use.

[0015] The aerosol-generating article may be configured as a heat-not-burn aerosolgenerating article. Heat-not-burn aerosol-generating articles are typically partially inserted into an oven, with a portion of the article remaining outside the oven. The oven is arranged to heat the aerosol-generating material to generate the aerosol. It is preferable that the visual indicator is disposed on the wrapper at a location that is not occluded by the oven when the aerosol-generating article is inserted into the oven. In this way, the visual indicator may be visible during use. The visual indicator may be disposed on a filter portion region of the wrapper. The filter portion region may be a region of the wrapper that surrounds the filter portion of the aerosol-generating article. In this way, the visual indicator may be located at a position that is proximate the filter portion. Such positioning may cause the visual indicator to directly react to a property of the filter portion or the aerosol flowing through the filter portion. For example, a temperature of the filter portion may directly affect the visual indicator. Advantageously, the visual feedback provided by the visual indicator may be more accurate.

[0016] The visual indicator may be disposed proximate a distal end of the filter portion region, wherein the distal end of the filter portion region is towards the aerosolgenerating portion. In this way, the visual indicator may be located at a position that is visible even during inhalation by the user.

[0017] The wrapper may comprise one or more ventilation holes. The visual indicator may be disposed downstream from the ventilation holes. In this way, the visual indicator may be located at a position that is proximate a flow of aerosol generated upon heating of the aerosol-generating material. By being positioned downstream from the ventilation holes, the visual indicator may interact with aerosol that directly influences the temperature of the filter portion. Such positioning may therefore advantageously facilitate the provision of a more accurate indicator of the temperature of the aerosol flowing through the filter portion. Furthermore, the one or more ventilation holes may typically be positioned such that, in use, the ventilation holes are outside of the oven. Therefore, by being positioned downstream from the ventilation holes, the visual indicator may be visible during use because it is not covered by the oven. In some embodiments, the visual indicator may be disposed upstream from the ventilation holes.

[0018] The visual indicator may be configured to provide a first visual feedback when the property reaches the first threshold and a second visual feedback when the property meets a second threshold. In this way, visual feedback may be provided to the user when the property meets at least two different levels. Advantageously, the visual indicator may provide additional information to the user. The property may be a temperature of the filter portion or the aerosol flowing through the filter portion and the first threshold may be a first temperature threshold. In this way, the visual indicator may provide visual feedback when the temperature of the filter portion or the aerosol flowing through the filter portion reaches the first temperature threshold. The visual indicator may be configured such that the first temperature threshold corresponds to a temperature of the filter portion that causes the user to experience an unwanted high temperature sensation. Advantageously, the visual indicator may inform the user that the aerosol-generating article is too hot for use.

[0019] Whilst it may be preferable that the property is a temperature is of the filter portion, it may be envisaged that the property could be a temperature of a different component of the aerosol-generating article, such as the aerosol-generating portion. It will be appreciated that the temperature of other components like the aerosol-generating portion still influences the temperature of the filter portion. However, this may be less reliable than when the visual indicator reacts to a temperature of the filter portion because other factors may influence the temperature of the filter portion.

[0020] The second threshold may be a second temperature threshold. In this way, the visual indicator may provide first visual feedback when the temperature of the filter portion or the aerosol flowing through the filter portion reaches the first temperature threshold and second visual feedback when the temperature of the filter portion reaches the second temperature threshold. Advantageously, the visual indicator may provide a means for providing more than one indication to the user.

[0021] The first temperature threshold may be 25°C and the second temperature threshold may be 50°C or above. In this way, the first visual feedback may be provided when the temperature of the filter portion reaches 25°C, and the second visual feedback may be provided when the temperature of the filter portion reaches 50°C. The temperature range of 25°C to 50°C may typically be an optimal temperature for use of the aerosol-generating article (i.e., for the user to take a puff or drag of the aerosol-generating article). Therefore, the visual indicator may advantageously provide an indication of an optimal time for the user to take a puff. Temperatures above 50°C may be too hot for use and as such, the second visual feedback may also advantageously indicate when not to take a puff.

[0022] The visual indicator may be further configured to provide further visual feedback when the temperature of the filter portion or the aerosol flowing through the filter portion is below the first temperature threshold. In embodiments wherein the first temperature threshold is 25°C, the visual indicator may advantageously indicate that the aerosol-generating article is not ready for use because it is not in the optimal temperature range. In embodiments wherein the first temperature threshold is 50°C or above, the visual indicator may advantageously indicate that the aerosol-generating article is at least safe for use.

[0023] The property may alternatively or additionally comprise a moisture of the aerosol flowing through the filter portion and the first threshold may alternatively or additionally comprise a first moisture threshold. The moisture of the aerosol flowing through the filter portion may influence the temperature of the filter portion. Advantageously, by providing visual feedback when the moisture of the aerosol flowing through the filter portion reaches the first moisture threshold, the visual indicator can indicate when a moisture of the aerosol flowing through the filter portion would cause the filter portion to be too hot for use.

[0024] The second threshold may be a second moisture threshold. In this way, the visual indicator may provide first visual feedback when the moisture of the aerosol flowing through the filter portion reaches the first moisture threshold and second visual feedback when the moisture of the aerosol flowing through the filter portion reaches the second moisture threshold. Advantageously, the visual indicator may provide more than one indication to the user.

[0025] In some implementations, the property comprises both the moisture of the aerosol flowing through the filter portion and the temperature of filter portion, and the first threshold comprises the first moisture threshold and the first temperature threshold. In such implementations, the visual indicator may advantageously provide indications in the form of visual feedback for both the temperature of the filter portion and the moisture of the aerosol flowing through the filter portion, both of which may indicate whether the aerosol-generating article is suitable for use. Similarly, the second threshold can comprise both the second temperature threshold and the second moisture threshold, thereby providing further information to the user.

[0026] The visual indicator may be reversible. That is, the visual indicator may be configured to return to a state in which the visual feedback is no longer provided. In this way, the visual indicator may advantageously indicate when the property no longer meets the first threshold. Thus, in situations where the temperature of the filter portion goes from being too hot (as indicated by the first property) to being a suitable temperature for use, the visual indicator may provide an indication as such by no longer providing visual feedback (or providing different visual feedback).

[0027] According to a second aspect of the present invention, there is provided a method of manufacturing an aerosol-generating article comprising: providing a filter portion and an aerosol-generating portion; connecting the filter portion and the aerosol-generating portion with a wrapper; and disposing a visual indicator on the wrapper, the visual indicator being configured to provide visual feedback when a property of the aerosol-generating article or an aerosol flowing through the filter portion meets a first threshold, said property influencing a temperature of the filter portion and said aerosol being generated upon heating of the aerosol-generating material.

[0028] Preferably, the step of disposing the visual indicator on the wrapper occurs after the step of connecting the filter portion and the aerosol-generating portion with the wrapper. The process of connecting the filter portion and the aerosol-generating portion may include rolling the wrapper around the aerosol-generating portion and the filter portion using a rolling apparatus. This process typically generates heat. By disposing the visual indicator on the wrapper after connecting the filter portion and the aerosol-generating portion (i.e., after using the rolling apparatus), unintended activation of the visual indicator may advantageously be mitigated. The method may further comprise one or more additional processing steps. The visual indicator is preferably disposed on the wrapper after these additional processing steps. These additional processing steps may produce heat. By disposing the visual indicator on the wrapper after the additional processing steps, any heat produced may not interact with the visual indicator. Advantageously, the risk of unintended activation of the visual indicator may be mitigated.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

[0031] Figure 1 shows a cross-sectional view of an aerosol-generating article according to an embodiment of the invention

[0032] Figure 2a shows a perspective view of the aerosol-generating article according to an embodiment of the invention;

[0033] Figure 2b shows a perspective view of the aerosol-generating article according to another embodiment of the invention;

[0034] Figure 3 shows a perspective view of an aerosol-generating article according to another embodiment of the invention;

[0035] Figure 4 shows a plot of a temperature of different parts of the aerosol-generating article over time until after a puff is taken by the user; and

[0036] Figure 5 shows a flow diagram of a method of manufacturing an aerosolgenerating article according to an embodiment of the invention.

[0037] DETAILED DESCRIPTION

[0038] Figure 1 shows a cross-sectional view of an aerosol-generating article 100 according to an embodiment of the invention. Figure 2a and 2b show perspective views of the aerosol-generating article 100 according to alternative embodiments of the invention. Figure 3 shows a perspective view of an aerosol-generating article 300 according to a further alternative embodiment.

[0039] The aerosol-generating article 100 comprises an aerosol-generating portion 120. The aerosol-generating portion 120 comprises an aerosol-generating material. The aerosol-generating material is any type of solid or semisolid material. Example types of aerosol-generating materials include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut leaves, cut filler, porous material, foam material or sheets. The aerosol-generating material typically comprises plant derived material and, in particular, tobacco.

[0040] In some implementations, the aerosol-generating material also comprises an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the aerosolgenerating material comprises an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some examples, the aerosol-generating material comprises an aerosol-former content of between approximately 10% and approximately 40% on a dry weight basis, and possibly approximately 10-15% on a dry weight basis.

[0041] Upon heating, the aerosol-generating material releases or generates an aerosol comprising volatile compounds. The volatile compounds typically include nicotine or flavour compounds such as tobacco flavouring. The aerosol-generating material typically also releases water vapour, especially during an initial phase of use. The amount of water vapour released by the aerosol-generating material is influenced by a moisture content of the aerosol-generating material.

[0042] The aerosol-generating article 100 also comprises a filter portion 110. The filter portion 110 comprises a filter material. The filter material typically comprises a type of polymer, for example cellulose acetate fibres. The filter portion 110 acts as a mouthpiece and also acts an air-permeable plug.

[0043] The aerosol-generating article 100 also comprises a wrapper 140 surrounding, circumscribing or connecting the aerosol-generating portion 120 and the filter portion 110. The wrapper 140 is a paper wrapper 140. The wrapper 140 comprises a filter portion region 142, which is a region of the wrapper 140 that surrounds or circumscribes the filter portion 110. The filter portion region 142 is the portion of the wrapper 140 that contacts the user’s lips during a puff of the aerosol-generating article 100.

[0044] As shown in Figure 1 , the aerosol-generating article 100 has a first end 150 (or mouth end or a downstream end) and a second end 152 (or a tip end or an upstream end). The filter portion 110 is located at the first end 150 and the aerosol-generating portion 120 is located at the second end 152. The aerosolgenerating article 100 comprises a first section 154, a second section 156, and a third section 158. The first section 154 comprises the aerosol-generating portion 120, e.g., a tobacco plug. In some implementations, the first section 154 could comprise a front plug (not shown) positioned upstream of the aerosol-generating portion 120. This front plug may abut the aerosol-generating portion 120 and may comprise a cellulose based material, such as cellulose acetate, paper, non-woven cellulose, or regenerated cellulose. The second section 156 includes a vapour outlet channel 160. The vapour outlet channel 160 is encompassed or defined by a hollow tube 170, for example, an paper tube or a hollow filter. The third section 158 includes the filter portion 110. Upon heating, the aerosol generated or released by the aerosol-generating material travels along the vapour outlet channel 160 towards the filter portion 110.

[0045] The wrapper 140 comprises one or more ventilation holes 146. The ventilation holes 146 are disposed about a circumference of the wrapper 140 that surrounds the vapour outlet channel 160. The ventilation holes 146 extend laterally through the hollow tube 170 to allow fluid communication between the vapour outlet channel 160 and an external environment. The ventilation holes 146 allow air to enter the vapour outlet channel 160 prior to flowing through the filter portion 110 when the user draws on the aerosol-generating article 100. This air can mix with the aerosol released upon heating of the aerosol-generating material, which can help control the temperature of the aerosol-generating material to prevent it from being too hot. The aerosol-generating article 100 is generally cylindrical or rod-shaped. The aerosol-generating article 100 is typically formed substantially in the shape of a stick, and broadly resembles a cigarette, having a tubular region with the aerosolgenerating portion 120 arranged in a suitable manner. The aerosol-generating article 100 may be a disposable and replaceable article which may, for example, contain tobacco as the aerosol-generating material. The aerosol-generating article 100 may be a heated tobacco stick.

[0046] The aerosol-generating article 100 further comprises a visual indicator 180. The visual indicator 180 is configured to provide visual feedback when a property of the aerosol-generating article 100 or an aerosol flowing through the filter portion 110 meets a first threshold. The aerosol flowing through the filter portion 110 is generated upon heating of the aerosol-generating material located in the aerosolgenerating portion 120.

[0047] The property of the aerosol-generating article 100 could be a property associated with any of the components of the aerosol-generating article 100 but is typically a property associated with the filter portion 110.

[0048] The property influences a temperature of the filter portion 110. For example, a change in the moisture of the aerosol-generating article 100 causes a change in the temperature of the aerosol flowing through the filter portion 110. This change in temperature may be proportional to the change in the property. This change in temperature causes a corresponding change in temperature of the wrapper portion (more particularly the filter portion region 142) that comes into contact with the user’s lips when the user takes a puff or drag of the aerosol-generating article 100. Accordingly, the property can be used to indicate to the user that the filter portion region 142 is too hot.

[0049] For the sake of brevity, the following discussion is with reference to a property of the filter portion 110. The property of the aerosol flowing through the filter portion 110 directly influences the property of the filter portion 110. Accordingly, discussion of the property of the filter portion 110 also means the property of the aerosol-flowing through the filter portion 110. The visual indicator 180 can be implemented in several ways. In one example, the visual indicator 180 comprises an ink comprising materials that change colour in response to changes in the property. In other examples, the visual indicator 180 comprises a coloured ink arranged behind a salt that is sensitive to changes in the property. In such examples, when the property reaches the first threshold, the material may become colourless or may no longer be present in the visual indicator, thereby revealing the coloured salt.

[0050] The visual indicator 180 of the embodiments of figures 2a and 2b are disposed on the wrapper 140. The visual indicator 180 is illustrated in Figures 2a and 2b as comprising a coloured band that traverses a circumference of the wrapper 140. However, the visual indicator 180 could take any suitable form, such as a logo or circle disposed on the wrapper 140. It is preferable that the visual indicator 180 is disposed at a location that is visible to the user during use (i.e. , whilst the user is taking a puff of the aerosol-generating article).

[0051] In the examples illustrated in Figures 2a and 2b, the visual indicator 180 is disposed on the filter portion region 142 of the wrapper 140. The visual indicator 180 is disposed proximate a distal end 144 of the filter portion region 142. The distal end 144 of the filter portion region 142 is towards the aerosol-generating portion 120. That is, the distal end 144 is an end of the filter portion region 142 that is closer to the aerosol-generating portion 120 than a proximal end (i.e., the first end 150).

[0052] The visual indicator 180 is disposed downstream from the ventilation holes 146. The visual indicator 180 could be disposed on the filter portion region 142 of the wrapper 140 or could be disposed on a portion of the wrapper 140 surrounding the vapour outlet channel 160. By being positioned downstream from the ventilation holes 146, a flow of aerosol adjacent the visual indicator 180 comprises the aerosol generated upon heating of the aerosol-generating material and the air entering via the ventilation holes 146. Thus, the visual indicator 180 interacts with aerosol that directly influences the temperature of the aerosol flowing through the filter portion 110. If the visual indicator 180 was positioned upstream from the ventilation holes 146, it may interact with aerosol that has not mixed with air entering via the ventilation holes 146. Whilst this aerosol still influences the temperature of the aerosol flowing through the filter portion 110, it may not be as accurate an indicator as aerosol that has mixed with air.

[0053] The visual indicator 180 is configured to change state in response to the first threshold being met. More particularly, the visual indicator 180 is configured to change from a first state (e.g., a first colour) to a second state (e.g., a second colour) in response to the first threshold being met. The first colour may be colourless such that the visual indicator 180 is not visible in ambient conditions (i.e., before the property of the aerosol-generating article 100 or aerosol flowing through the filter portion 110 reaches the first threshold). The second colour could be any colour such that when the first threshold is met, the visual indicator 180 becomes visible to the user. Alternatively, the first colour could be any colour such that the visual indicator 180 is visible in ambient conditions, and the second colour could be colourless such that the visual indicator 180 is not visible when the property meets the first threshold. Alternatively, the first colour and the second colour could both be different colours visible to the user.

[0054] In some implementations, the visual indicator 180 is reversible. For example, the colour change is reversible. That is, the visual indicator 180 changes from the first colour to the second colour when the first threshold is met, and changes from the second colour to the first colour when the first threshold is no longer met. For example, if the property returns to a value below the first threshold, the visual indicator 180 returns to the first colour. Thus, the user can judge, based on the state of the visual indicator 180, whether the aerosol-generating article 100 is safe for use.

[0055] Alternatively, the visual indicator 180 could be irreversible such that when the first threshold is met, the state of the visual indicator 180 does not change even when the first threshold is no longer met. An irreversible visual indicator 180 could be implemented using a coloured ink arranged behind a colourless (or coloured) salt that dissolves when the first threshold is met. Accordingly, when the first threshold is met, the coloured ink becomes visible. The visual indicator 180 could be configured to provide a variable transition between the first state and the second state. For example, the visual indicator 180 could continuously change colour between the first colour and the second colour as the property approaches the first threshold. Continuing with the example of the first colour being colourless, the visual indicator 180 could continuously change from being colourless to being coloured as the property approaches the first threshold. This colour change could be in the form of a change in opacity of the second colour. The visual indicator 180 may continue to change colour after the first threshold is met, thus indicating a maximum value of the property that has been reached.

[0056] In a first example, the visual indicator 180 is configured to provide visual feedback when a temperature of the filter portion 110 or the aerosol flowing through the filter portion 110 meets a first temperature threshold. The temperature of the aerosolgenerating article 100 influences the aerosol generated upon heating of the aerosol-generating material. In the context of this invention, the temperature of the aerosol flowing through the filter portion 110 is also considered to be a property that influences the temperature of the aerosol flowing through the filter portion 110.

[0057] The visual indicator 180 could comprise a thermochromic material that is reversible. For example, the visual indicator could comprise thermochromic pigments such as Chromazone, which causes the visual indicator 180 to become clear (i.e., colourless) at a defined temperature (i.e., the first temperature threshold). When the temperature decreases below the first temperature threshold, the Chromazone pigments cause the visual indicator 180 to become coloured again. It will be appreciated that the visual indicator 180 could additionally or alternatively comprise other reversible thermochromic materials. For example, the visual indicator 180 could comprise a lactone-based dye.

[0058] In use, the user can judge based on the visual feedback (e.g., clear or visible) provided by the visual indicator 180 whether the aerosol-generating article 100 is too hot for contact with the user’s lips. In this example, if the visual indicator 180 becomes clear (i.e., indicating that the first temperature threshold has been met), the user can wait for the visual indicator 180 to become visible before taking a puff.

[0059] In this implementation, the first temperature threshold is typically 50°C because temperatures of 50°C and above are likely to be too hot for the user’s lips. Thus, the visual indicator 180 provides visual feedback when the temperature of the aerosol-generating article 100 or the aerosol flowing through the filter portion 110 reaches 50°C. In some implementations, the first temperature threshold is 60°C. It will be appreciated that the first temperature threshold can be configured based on the materials used in the visual indicator 180.

[0060] The visual indicator 180 could alternatively comprise a thermochromic material that is irreversible. For example, the visual indicator 180 could comprise thermochromic pigments such as Kromagen, which cause the visual indicator 180 to become clear (i.e., colourless) at a defined temperature (i.e., the first temperature threshold). When the temperature of the thermochromic pigments returns to a temperature below the defined temperature threshold, the visual indicator 180 remains clear. It will be appreciated that the visual indicator 180 could additionally or alternatively comprise other irreversible thermochromic materials, such as Thermax.

[0061] Accordingly, in use the visual indicator 180 can provide a means for indicating to the user which aerosol-generating articles 100 in a pack have been used. In particular, continuing with the present example, aerosol-generating articles 100 having a visual indicator 180 that is in the second state can be identified as used. Aerosol-generating articles 100 having a visual indicator 180 that is in the first state can be identified as unused.

[0062] When the visual indicator 180 comprises a thermochromic material that is irreversible and is configured to provide a variable transition between the first state and the second state, the visual indicator 180 may indicate a maximum temperature reached. In particular, since the visual indicator 180 continues to change colour even after the first temperature threshold is met, and does not revert back to the first state, the visual indicator 180 will remain at the colour associated with the highest temperature reached.

[0063] The visual indicator 180 can also be used to indicate a preferred time to inhale. In particular, during use, the temperature of the filter portion 110 will change with time. The temperature will increase as water is vapourised, until a maximum temperature is reached, at which point the temperature begins to decrease. The visual indicator 180 remains at the colour associated with the highest temperature reached. This colour associated with the highest temperature reached can be used by the user to determine their preferred time to inhale.

[0064] In a second example, the visual indicator 180 is configured to provide visual feedback when a moisture of the aerosol-generating article 100 or a moisture of the aerosol flowing through the filter portion 110 meets a first moisture threshold. In this example, the visual indicator 180 may comprise an ink comprising one or more of: Curcumin, betacyanins, shikonin, alizarin, litmus, naphthoquinone, spirulina sp., or anthocyanidins. Of these, compounds from the anthocyanidins are preferable because they are suitable for food-grade applications and have a higher sensitivity to moisture changes than comparable compounds. Thus, the visual indicator 180 preferably comprises one or more of: Pelargonidin, Cyanidin, Peonidin, Delphinidin, Petunidin and Malvidin.

[0065] Figure 4 shows a plot 400 of a temperature of different parts of the aerosolgenerating article 100 over time until after a puff is taken by the user. A first curve 402 shows a temperature of the filter portion 110 when the aerosol flowing through the filter portion 110is at a first moisture. A second curve 404 shows a temperature of the filter portion 110 when the aerosol flowing through the filter portion 110 is at a second moisture. The first moisture is a low moisture with respect to the second moisture, which is a high moisture. A third curve 406 shows a temperature of the aerosol-generating portion 120, for example a temperature of the tobacco in the aerosol-generating portion. A first portion 408 of the plot 400 represents a heatup (or a pre-heating) phase 408 in which the temperature of the aerosolgenerating material increases to an operational level (i.e. , a temperature at which the user is to take a puff). A second portion 410 of the plot 400 represents a puff phase 410 in which the user takes a puff from the aerosol-generating article 100. It will be appreciated that the plot 400 is not to scale and is intended to convey the influence that moisture has on the temperature of the filter portion 110.

[0066] As shown in the plot 400, when the moisture of the aerosol flowing through the filter portion 110 is low, a temperature change of the filter portion 110 during the puff phase 410 is relatively small. When the moisture of the aerosol flowing through the filter portion 110 is high, a temperature change of the filter portion 110 during the puff phase 410 is relatively high. Therefore, the moisture of the aerosol flowing through the filter portion 110 significantly influences the temperature of the filter portion 110 when the user takes a puff.

[0067] The moisture of the aerosol-generating material 100 influences how much water vapour is generated when the aerosol-generating material is heated up. At higher levels of humidity, more hot water vapour or aerosol is generated from moisture present in the aerosol-generating portion 120. This is because water has a lower boiling point than other materials present in the aerosol-generating portion 120. When there is airflow through the aerosol-generating article 100 (for example when the user takes a puff), aerosol comprising this water flows to the filter portion 110. The filter portion 110 absorbs energy carried by the water present in the aerosol flowing through the filter portion 110, causing it to heat up along with a portion of the surrounding wrapper 140. As a result, when this heated wrapper 140 comes into contact with the user’s lips during inhalation, the user may experience a high temperature sensation.

[0068] Additionally, components of the aerosol-generating article 100 located between the aerosol-generating portion 120 and the filter portion 110 can be considered analogous to a resistor, with the humidity of the aerosol-generating article 100 being of factor of resistance. The temperature of the filter (Tf) can be described as a function relating to the temperature of the aerosol-generating portion 120 (To) and the humidity of the aerosol-generating article 100 (H):

[0069] Tf= f T0, H) As demonstrated by Figure 4, higher humidity causes lower the “resistance” and a higher heat at the filter portion 110.

[0070] The moisture of the aerosol-generating material typically corresponds to the moisture of the wrapper 140. Therefore, in implementations where the visual indicator 180 is positioned on the wrapper 140, and is thus influenced by the moisture of the wrapper 140, the visual indicator 180 indicates a moisture of the aerosol-generating material. By extension, the visual indicator 180 indicates the temperature of the filter portion 110 when the user takes a puff.

[0071] By providing visual feedback when the moisture of the aerosol-generating article 100 or the aerosol flowing through the filter portion 110 reaches the first moisture threshold, the user is alerted that taking a puff of the aerosol-generating article 100 could cause a high temperature spike at the filter portion 110. Advantageously, the visual indicator 180 indicates the temperature of the filter portion 110 when the user takes a puff even before the aerosol-generating material is heated.

[0072] In implementations where the visual indicator 180 is irreversible, the visual indicator 180 can indicate that the seal of a packaging associated with the aerosolgenerating article 100 has been broken or the moisture levels during production were too high.

[0073] Alternatively, in implementations where the visual indicator is reversible, the visual indicator 180 can indicate the actual moisture of the aerosol-generating article 100. For example, if the moisture of the aerosol-generating article 100 reaches the first moisture threshold, the visual indicator 180 provides visual feedback. When the moisture of the aerosol-generating article 100 no longer meets the first moisture threshold (e.g., if the aerosol-generating article 100 has dried), the visual indicator 180 will no longer provide visual feedback.

[0074] In some implementations, the visual indicator 180 is configured to provide first visual feedback when the property reaches the first threshold and second visual feedback when the property meets a second threshold. In this implementation, the visual indicator 180 is in one of three states. A first state is when the property has not reached the first or second threshold. A second state is when the property has reached the first threshold. A third state is when the property has reached the third threshold. A reference visual indicator can be provided, for example as part of a packaging for the aerosol-generating article 100. The reference visual indicator can show a correspondence between the visual feedback shown by the visual indicator 180 and the state of the visual indicator 180.

[0075] To achieve this implementation, the visual indicator 180 may comprise a first indicator 181 and a second indicator 182 (shown in Figure 2b). The first indicator 181 and the second indicator 182 are both positioned downstream from the ventilation holes 146. The first indicator 181 is configured to provide the first visual feedback when the property reaches the first threshold. The second indicator 182 is configured to provide the second visual feedback when the property reaches the second threshold. It may be preferable that the second indicator 182 is positioned further away from the first end 150 than the second indicator 181 so that it is more likely to be visible whilst the user takes a drag from the aerosolgenerating article 100.

[0076] Alternatively, this implementation may be achieved using a single visual indicator 180 like the aerosol-generating article 100 of Figure 2a. The visual indicator 180 can comprise a first active ingredient arranged to change colour when the first threshold is reached, and a second active ingredient arranged to change colour when the second threshold is reached.

[0077] Continuing with the temperature property example, the property is a temperature of the aerosol-generating article 100 (e.g., the filter portion 110) or the aerosol flowing through the filter portion 110, the first threshold is a first temperature threshold, and the second threshold is a second temperature threshold. This configuration may be achieved by layering or mixing a first thermochromic pigment and a second thermochromic pigment. The first thermochromic pigment is configured to change colour at the first temperature threshold. The second thermochromic pigment is configured to change colour at the second temperature threshold. The first and second thermochromic pigments can be mixed in specific proportions to achieve this desired multi-phase colour indication.

[0078] The first temperature threshold is between 20°C and 30°C, typically 25°C, and the second temperature threshold is between 45°C and 55°C, typically 50°C. Therefore, the visual indicator 180 provides first visual feedback when it reaches 25°C and provides second visual feedback when it reaches 50°C. When the visual indicator 180 is in the first state (i.e., neither temperature thresholds have been reached), this can indicate that the aerosol-generating article 180 is not being used, or is too cold to be inhaled, and needs to be heated up before the user can take a drag. When the visual indicator 180 is in the second state (i.e., the first temperature threshold has been reached), this can indicate that the aerosolgenerating article 180 is at an optimal temperature for use because the temperature range of 25°C to 50°C is typically optimal for aerosol-generating articles of the heat-not-burn type. When the visual indicator 180 is in the third state (i.e., the second temperature threshold has been reached), this can indicate that the aerosol-generating article 180 is too hot for use.

[0079] In a further alternative implementation, the visual indicator 180 is configured to provide first visual feedback when the moisture of the aerosol-generating article 100 or the moisture of the aerosol flowing through the filter portion 110 meets a first moisture threshold. The visual indicator 180 is further configured to provide second visual feedback when the moisture of aerosol-generating article 100 or the moisture of the aerosol flowing through the filter portion 110 meets a first temperature threshold. This implementation can be achieved using the first indicator 181 and the second indicator 182 as shown in Figure 2b or can be achieved by layering hydrochromic and thermochromic materials on a single visual indicator 180 as shown in Figure 2a.

[0080] A packaging associated with the aerosol-generating article 100 could comprise a reference chart that indicates a correspondence between the visual feedback provided by the visual indicator 180 and the property. For example, the reference chart could comprise a key of colours that the visual indicator 180 turns to, and corresponding descriptions of the state of the aerosol-generating article 100. With regard to the positioning of the visual indicator 180 on the wrapper 140, it has been found that an optimal position has been found to be 16 mm from the first end 150 of the aerosol-generating article 100 having a filter portion 110 of length 20 mm, a hollow tube 170 of 20 mm, and an aerosol-generating portion 120 of length 20 mm.

[0081] Figure 5 shows a flow diagram of a method 500 of manufacturing an aerosolgenerating article according to an embodiment of the invention. The method 500 is for manufacturing an aerosol-generating article such as the aerosol-generating article 100 or the aerosol-generating article 300.

[0082] Step 502 of the method 500 comprises providing a filter portion and an aerosolgenerating portion. For example, step 502 comprises providing the filter portion 110 and the aerosol-generating portion 120 of the aerosol-generating article 100. This step 502 may also comprise providing a hollow tube (e.g., hollow tube 170) defining a vapour outlet channel (e.g., vapour outlet channel 160).

[0083] Step 504 of the method 500 comprises connecting the filter portion and the aerosol-generating portion with a wrapper. For example, step 504 comprises surrounding the filter portion 110 and the aerosol-generating portion 120 with the wrapper 140 of the aerosol-generating article 100. Step 504 may also comprise surrounding the hollow tube with the wrapper, wherein the hollow tube is between the filter portion and the aerosol-generating portion. This step typically includes rolling the wrapper 140 around the aerosol-generating portion 120 and the filter portion 110 using a rolling apparatus (not shown).

[0084] Step 506 of the method 500 comprises disposing a visual indicator on the wrapper. For example, step 506 comprises disposing the visual indicator 180 of the aerosolgenerating article 100 on the wrapper 140. Step 506 occurs after step 504 to prevent any heat generated during rolling affecting the visual indicator 180.

[0085] The method 500 typically also comprises cutting one or more ventilation holes in the wrapper 140. For example, the one or more ventilation holes 146 are cut in the wrapper 140. Since the ventilation holes 146 extend through the hollow tube 170, this step also involves cutting the hollow tube 170. This may be achieved by using a laser to cut the one or more ventilation holes in the wrapper 140 and the hollow tube 170.

[0086] To prevent heat from the laser from affecting the visual indicator 180, the step of disposing 506 the visual indicator 180 on the wrapper 140 is carried out after the one or more ventilation holes 146 are cut in the wrapper 140.

[0087] Figure 3 shows a perspective view of an aerosol-generating article 300 according to another embodiment of the invention.

[0088] The aerosol-generating article 300 is substantially similar to the aerosolgenerating article 100 and comprises: the filter portion 110 comprising a filter material; the aerosol-generating portion 120 comprising an aerosol-generating material; the wrapper 140 connecting the filter portion 110 and the aerosolgenerating portion 120; and a visual indicator 380 disposed on filter portion 110 and configured to provide visual feedback when a property of the aerosolgenerating article 100 or an aerosol flowing through the filter portion 110 meets a first threshold, said property influencing a temperature of the filter portion 110 and said aerosol being generated upon heating of the aerosol-generating material.

[0089] Therefore, the aerosol-generating article 300 is distinguished over the aerosolgenerating article 100 in that the visual indicator 380 is disposed on the filter portion.

Claims

CLAIMS1 . An aerosol-generating article comprising: a filter portion comprising a filter material; an aerosol-generating portion comprising an aerosol-generating material; a wrapper connecting the filter portion and the aerosol-generating portion; and a visual indicator disposed on the wrapper and configured to provide visual feedback when a property of the aerosol-generating article or an aerosol flowing through the filter portion meets a first threshold, said property influencing a temperature of the filter portion and said aerosol being generated upon heating of the aerosol-generating material.

2. The aerosol-generating article of claim 1 , wherein the visual indicator is disposed on a filter portion region of the wrapper.

3. The aerosol-generating article of claim 2, wherein the visual indicator is disposed proximate a distal end of the filter portion region, wherein the distal end of the filter portion region is towards the aerosol-generating portion.

4. The aerosol-generating article of claim 1 , wherein the wrapper comprises one or more ventilation holes and wherein the visual indicator is disposed downstream from the ventilation holes.

5. The aerosol-generating article of any preceding claim, wherein the visual indicator is configured to provide a first visual feedback when the property reaches the first threshold and a second visual feedback when the property meets a second threshold.

6. The aerosol-generating article of any preceding claim, wherein the property is a temperature of the filter portion or the aerosol flowing through the filter portion and the first threshold is a first temperature threshold.

7. The aerosol-generating article of claim 6 when dependent on claim 5, wherein the second threshold is a second temperature threshold.

8. The aerosol-generating article of claim 7, wherein the first temperature threshold is 25°C and the second temperature threshold is 50°C or above.

9. The aerosol-generating article of any of claims 6 to 8, wherein the visual indicator is further configured to provide further visual feedback when the temperature of the filter portion or the aerosol flowing through the filter portion is below the first temperature threshold.

10. The aerosol-generating article of any of claims 1 to 5, wherein the property comprises a moisture of the aerosol flowing through the filter portion, and the first threshold comprises a first moisture threshold.

11. The aerosol-generating article of claim 10 when dependent on claim 5, wherein the second threshold is a second moisture threshold.

12. The aerosol-generating article of any preceding claim, wherein the visual indicator feedback is reversible.

13. The aerosol-generating article of any preceding claim, configured as a heat-not-burn aerosol-generating article.

14. The aerosol-generating article of any preceding claim, wherein the property of the aerosol-generating article is a property associated with the filter portion.

15. A method of manufacturing an aerosol-generating article comprising: providing a filter portion and an aerosol-generating portion; connecting the filter portion and the aerosol-generating portion with a wrapper; and disposing a visual indicator on the wrapper, the visual indicator being configured to provide visual feedback when a property of the aerosol-generating article or an aerosol flowing through the filter portion meets a first threshold, said property influencing a temperature of the filter portion and said aerosol being generated upon heating of the aerosol-generating material.

16. The method of manufacture of claim 15, wherein the step of disposing the visual indicator on the wrapper occurs after the step of connecting the filter portion and the aerosol-generating portion with the wrapper.

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