Patent Application
20240423274
The present invention relates to a pod including a temperature-switchable material for an aerosol-generating device, in particular an electronic cigarette, vaporizer or e-vapor pod system, and an aerosol-generating device comprising said pod.
Aerosol-generating devices, such as electronic cigarettes or “e-cigarettes” as they are also known, have gained in popularity over the past ten years as an alternative to traditional smoking articles, like cigarettes, cigars, and cigarillos. Developments in the design and configuration of such aerosol generating devices or vaporizer devices are on-going to improve their performance and their reliability, as well as their ease of production and their production costs.
Conventional aerosol generating devices usually include an atomizer such as a heater, a power supply (e.g. an electrical power source) and a pod comprising a wick and a liquid reservoir that contains flavoured e-liquid. The e-liquid can be volatized using the heater and transferred to a user of the aerosol generating device in an airflow, which is preferably guided through a mouthpiece of the device.
In order to provide a convenient way for a user to load the e-liquid into the aerosol generating device and to avoid the need for the user to handle the e-liquid directly, thereby reducing the likelihood of spillage and waste, pods are conventionally provided.
The flow of e-liquid through the wicking material in e-cigarettes must be sufficient to avoid dry puffs. However, permeation of the e-liquid through the wicking material of the pod will contribute to undesired leakage of the e-liquid as it does not evaporate when the e-cigarette is not in use, in particular during storage and transit.
WO 2015/070405 A1 relates to an atomizer for an electronic cigarette comprising an oil-storage mechanism and an atomizing component. A cigarette oil flowing channel is used for supplying cigarette oil stored within the oil-storage mechanism to the atomizing component. A hot-melt sealing structure is used for sealing the cigarette oil flowing channel before using the atomizer for the first time. When using the electronic cigarette for the first time and powering on the atomizing component for the first time, the hot-melt sealing structure is heated and melted to open the cigarette oil flowing channel, thus allowing the cigarette oil to be supplied to the atomizing component. However, according to WO 2015/070405 A1, leakage can only be prevented before the electronic cigarette is used for the first time. Once the hot-melt sealing structure is melted, it cannot reseal the cigarette oil flowing channel and leakage can occur during long periods of not using the electronic cigarette.
WO 2020/070109 A1 concerns a liquid supply system such as a cartridge (pod) for use with aerosol-generating devices, which includes a liquid substrate in a retention material, a liquid flow channel extending from the liquid retention material and a barrier layer disposed in the liquid flow channel. The barrier layer that is included in the cartridge prevents premature transfer of the liquid substrate into the airflow passage. The barrier has a degradation temperature between 60° C. and 130° C. at which it degrades and allows transfer of the liquid substrate into the liquid flow channel. However, according to WO 2020/070109 A1, leakage can only be prevented before the aerosol-generating device is used for the first time. Once the barrier layer is degraded, it cannot reseal the liquid flow channel and leakage can occur during long periods of not using the aerosol-generating device.
In view of the above, it is an object of the invention to provide a pod for an aerosol-generating device, which can prevent leakage of an aerosol-generating liquid material (e-liquid) during transit and storage before the aerosol-generating device is used for the first time and also afterwards, during long periods of not using the aerosol-generating device.
This aim is achieved by a pod for an aerosol-generating device as defined in claim 1 and an aerosol-generating device as defined in claim 14. Preferable embodiments of the invention are defined in the dependent claims, the following description and the accompanying drawings.
A core idea of the present invention lies in a pod for an aerosol-generating device, which allows for the flow of the e-liquid to be selectively switched on so that the e-liquid can be supplied to the heating element when the pod is in use. This is achieved by including a temperature-switchable material in the pod, which coats or forms a porous wick and is arranged so that a discharge opening of a reservoir including the e-liquid is sealed. Below its transition temperature and before being heated, the temperature-switchable material is impermeable for the e-liquid, thus preventing leakage of the e-liquid during storage or transit in non-use periods. When in use, the temperature-switchable material is heated up to its transition temperature at which it becomes permeable for the e-liquid, which can then be supplied to the heating element and vaporized. During subsequent long periods of storage or transportation below the transition temperature of the temperature-switchable material, the temperature-switchable material again becomes impermeable to the e-liquid, thus preventing leakage.
The term “aerosol-generating liquid material” is interchangeably used with the term “e-liquid” and refers to the liquid material from which the aerosol is created in an aerosol-generating device using for example a vaporizer, an atomizer, a nebulizer or a heating element.
The term “aerosol-generating device” refers to a device that can generate an aerosol for inhalation, such as an electronic cigarette, a vaporizing device, a nebulizing device, an e-vapor pod system or an inhalation device.
The term “temperature-switchable material” refers to an amphiphilic material having a transition temperature of between 25° C. and 300° C., preferably between 50° C. and 100° C., which is superhydrophobic and impermeable for an aerosol-generating liquid material below the transition temperature and which becomes superhydrophilic and permeable for an aerosol-generating liquid material when being exposed to a temperature above said transition temperature. This instantaneous liquid permeation switching (temperature-induced wettability change) is valuable in e-vapor pod systems where the porous media is desired to be in an OFF state when in storage/transit but needs to rapidly switch to an operational ON state when in use, i.e. heated. This helps reducing leakage risks during storage and transport.
The term “superhydrophobic” refers to materials exhibiting a large water contact angle of at least 150° and the term “superhydrophilic” refers to materials a small water contact angle of less than about 10°.
The term “porous wick” refers to a wicking material having a porosity of 30% to 60% and preferably 40% to 50%, wherein the porosity is a fraction of the volume of voids over the total volume of the wicking material. The porosity can be measured by microscope image analysis. Optionally, the porous wick comprises a vapor channel structure.
The term “sol-gel foam” refers to a silicon alkoxide material having a porous microstructure obtained from a sol-gel process as described in Shirtcliffe et al. “Porous materials show superhydrophobic to superhydrophilic switching”, Chemical Communications, 2005, 3135-3137.
The present invention relates to a pod (1) for an aerosol-generating device (10), which comprises a porous wick (2) and a reservoir (3). The reservoir (3) includes a discharge opening (4), through which an aerosol-generating liquid material (e-liquid) can be discharged when using the aerosol-generating device (10).
According to option (i) of the invention, the porous wick (2) is coated with a temperature-switchable material (6) on that surface of the porous wick (2) that seals the discharge opening (4) of the reservoir (3). In option (i), the temperature-switchable material (6) is arranged between the discharge opening (4) of the reservoir (3) and the porous wick (2) and forms a superhydrophobic barrier preventing the e-liquid to permeate into the porous wick (2) when the pod (1) is not used, i.e. during storage and transportation, thus avoiding leakage. When in use, the properties of the temperature-switchable material (6) are switched so that it becomes superhydrophilic and the e-liquid can permeate into the porous wick (2) and be subsequently vaporized.
According to option (ii) of the invention, the porous wick (2) is coated with a temperature-switchable material (6) on that surface of the porous wick (2) that is arranged opposite to the surface of the porous wick sealing the discharge opening (4) of the reservoir (3). In option (ii), the discharge opening (4) is directly sealed by the porous wick (2), which is thus arranged between the temperature-switchable material (6) and the reservoir (3). The porous wick (2) is however coated on its remaining surface, that does not seal the discharge opening (4) of the reservoir with the temperature-switchable material (6) so that the e-liquid can permeate into the porous wick (2) during periods of not using the pod (1), but cannot leak out of the pod (1) due to the hydrophobic barrier layer provided by the temperature-switchable material (6) coating on the porous wick (2). During use, the properties of the temperature-switchable material (6) are switched to superhydrophilic so that layer becomes permeable for the e-liquid which can subsequently be vaporized.
According to option (iii) of the invention, the porous wick (2) is made of the temperature-switchable material (6) and is arranged so that a surface of the porous wick (2) seals the discharge opening (4) of the reservoir (3). During periods of not using the pod (1), the porous wick (2) forms a superhydrophobic barrier and remains impermeable to the e-liquid, thus preventing leakage. When in use, the porous wick (2) that is fully made of the temperature-switchable material (6) is switched to become superhydrophilic and the e-liquid can permeate into the wick and be subsequently vaporized.
The temperature-switchable material (6) used in the present invention is an amphiphilic material, which is impermeable for an aerosol-generating liquid material below a transition temperature of between 25° C. and 300° C. and which becomes permeable for an aerosol-generating liquid material when being exposed to a temperature above said transition temperature. The present invention makes uses of a switching mechanism based on temperature. That is, when heating the temperature-switchable material (6) up to its transition temperature its wettability characteristics change. In particular, when heating the temperature-switchable material (6) up to its transition temperature for the first time, its superhydrophobic properties are switched instantaneously to become superhydrophilic. These superhydrophilic properties of the temperature-switchable material (6) are switched back to become superhydrophobic and impermeable for the e-liquid when the pod (1) is not in use, such as during storage or transit at a temperature below the transition temperature.
The transition temperature of the temperature-switchable material (6) is between 25° C. and 300°° C., preferably between 50° C. and 100° C., as such a transition temperature allows the switching to be triggered by the heating of the e-liquid for evaporation.
The temperature-switchable material (6) is a porous material with pores having a pore diameter preferably in the range of between 5 μm and 50 μm, more preferably between 10 μm and 40 μm and even more preferably between 15 μm and 30 μm. While the above-described switching, i.e. the transition from superhydrophobic and impermeable for the e-liquid to superhydrophilic and permeable for the e-liquid, can also be obtained in non-porous films, the switching in non-porous films is a more gradual transition. In contrast thereto, porous materials enable a (near)-instantaneous switching. This fast switching ability of porous materials has been ascribed to the fact that a liquid can either enter the pores or not and no transition state is possible. Therefore, when applying a porous film with temperature-switchable wettability characteristics onto a porous wick structure, switchable liquid flow into and/or out of the wick is advantageously enabled by a rapid superhydrophobic to superhydrophilic switching. The temperature-switchable material (6) can therefore reduce leakage of e-liquid until it is heated above its transition temperature. It is especially advantageous to employ porous materials showing temperature-induced wettability switching as the transition is fast and distinct. The temperature-switchable material (6) can be entirely made of one material or can be a composite material of different materials.
The temperature-switchable material (6) is preferably a porous material made from silicon alkoxide. The silicon alkoxide may contain at least one of phenyltriethoxysilane (PhTEOS), methyltriethoxysilane (MTEOS) and tetraethyl-orthosilicate (TEOS). By varying the ratio of PhTEOS, MTEOS and/or TEOS, the transition temperature of the temperature-switchable material (6) can be tuned. Specifically, when increasing the PhTEOS fraction in the temperature-switchable material (6), the temperature at which the wettability switch occurs is increased. On the other hand, when increasing the TEOS fraction in the temperature-switchable material (6), the transition temperature is decreased. Equally, when using MTEOS instead of PhTEOS in the temperature-switchable material (6), the transition temperature is lowered, because the methyl group contained in MTEOS is less bulky than the phenyl group contained in PhTEOS. The ratio of PhTEOS or MTEOS and TEOS ([PhTEOS or MTEOS]/[TEOS]) in the temperature-switchable material (6) is preferably between 1:3 to 2:1. For example, when the temperature-switchable material (6) is made of PhTEOS and TEOS in a ratio of ([PhTEOS]/[TEOS]) of 1:2, a transition temperature of about 275° C. (+10° C.) has been reported (Shirtcliffe et al., “Porous materials show superhydrophobic to superhydrophilic switching”, Chemical Communications, 2005, 3135-3137).
The porous material made from silicon alkoxide is preferably a sol-gel foam, which can be prepared by the sol-gel preparation method described in Shirtcliffe et al. “Porous materials show superhydrophobic to superhydrophilic switching”, Chemical Communications, 2005, 3135-3137.
When the temperature-switchable material (6) is a silicon alkoxide sol-gel foam, the switch in liquid permeation occurs due to the change from hydrophobic to hydrophilic with virtually no transition period. Without wishing to be bound by any theory, it is believed that a change in morphology of the inner pore surface occurs upon exposure of porous silicon alkoxide materials to higher temperatures as explained in the following. The hydrophobic to hydrophilic switch may occur due to the crosslinked silica backbone of the sol-gel foam causing redistribution of the organic groups contained in the sol-gel foam (i.e. a methyl group or a phenyl group) from the surface of the pores of the sol-gel foam into the bulk of the material when being heated to the respective transition temperature. Below the transition temperature, the organic groups cover the inside of the pores of the sol-gel foam, which causes the material to be hydrophobic at first. Higher temperatures may cause cleavage of the Si—O—Si-bonds thus forming Si-OH groups, which can subsequently lead to a rearrangement of the organic groups contained in the sol-gel structure, whereby the inside of the pores is rendered more polar and therefore hydrophilic. The wettability switch may therefore be explained by a migration of these organic groups away from the pore surfaces and into the bulk of the silicon alkoxide sol-gel material.
In the pod (1) according to option (i) of the present invention, the porous wick (2) may have a vapor channel structure (7) forming vapor channels (7a) on a surface of the porous wick (2) that is arranged opposite to the surface sealing the discharge opening (4) as shown in
In the pod (1) according to option (ii) and option (iii) of the invention, the temperature-switchable material (6) may comprise a vapor channel structure (7) forming vapor channels (7a) in a surface of the porous wick (2) that is arranged opposite to the surface of the porous wick (2) sealing the discharge opening (4). This vapor channel structure (7) allows for airflow control and vaporization rate control of the wick structure but does not interrupt the barrier function of the temperature-switchable material (6) when the pod (1) is not in use. Larger vapor channels increase the speed of the airflow and create a greater surface, which leads to an increase of the vaporization rate. That is, even when comprising such a vapor channel structure (7), the temperature-switchable material (6) is arranged to cover the porous wick (2) sealing the discharge opening (4) of the reservoir (3) so as to prevent the e-liquid from leaking out. The direction of the vapor channels (7a) is not particularly limited. Preferably, the channels run parallel to the airflow.
The vapor channel structure (7) can have a geometrical structure selected from the group consisting of pin fins, rectangular channels, circular channels, re-entrant cavities and flow mixer structures.
In addition to the vapor channel structure (7), the pod (1) of option (ii) or option (iii) may comprise a heat transfer material layer (8) arranged adjacent to the vapor channel structure (7) for enhancing the heat supply to the temperature-switchable material (6) and reducing the time of the temperature-induced wettability change. Moreover, the pod (1) can further metal (9) a comprise a mesh having temperature-switchable coating, wherein the metal mesh (9) is arranged between the vapor channel structure (7) of the temperature-switchable material (6) and the heat transfer material layer (8). Thus, the metal mesh (9) is provided in direct contact with the heat transfer material layer (8). As a result, the time from when the heater is switched on to the temperature-induced wettability change is further reduced.
The metal mesh (9) can be made of Al, Cu, NiCr or stainless steel and is preferably made of stainless steel. The temperature-switchable coating of the metal mesh (9) can be made of the same material as described above for the temperature-switchable material (6). The coated metal mesh (9) therefore has the same temperature switchable properties as described above for the temperature-switchable material (6), i.e. from being superhydrophobic below the transition temperature of the coating material to becoming superhydrophilic above said transition temperature. Such a coated metal mesh structure (9) can be prepared as described in Yang et al. “Functional silica film on stainless steel mesh with tunable wettability”, Surface & Coatings Technology, 2011, 205, 5387-5393.
The thickness of the temperature-switchable material (6) in a pod (1) according to option (i) and option (ii) of the invention, wherein the temperature-switchable material (6) is provided as a coating layer of the porous wick (2), is preferably between 0.0001 mm and 1 mm, more preferably between 0.0005 mm and 0.25 mm, and even more preferably between 0.001 mm and 0.1 mm.
The thickness of the temperature-switchable material (6) in a pod (1) according to option (iii) of the invention, wherein the porous wick (2) is made of the temperature-switchable material (6), is preferably between 0.1 mm and 10 mm, more preferably between 0.25 mm and 7.5 mm, and even more preferably between 1 mm and 5 mm.
In the pod (1) according to option (ii) of the invention, the temperature-switchable material (6) can be sandwiched between two or more porous wicks (2) or can be located on that surface of the porous wick (2) that does not seal the discharge opening (4) of the reservoir (3).
The porous wick (2) used in the pod (1) of option (i) and option (ii) of the invention can be made entirely from one material or can be a composite material of different porous wicks. The porous wick (2) can for example be made of ceramic, silica or cotton, wherein a ceramic wick is preferable from the viewpoint of providing excellent mechanical properties, particularly in terms of rigidity. Ceramic wicks are, for example, not influenced by compression like cotton wicks. Furthermore, ceramic is a stable, inert and cheap material, which is mass producible.
The pod (1) of the present invention can further comprise an airflow channel (5). Air can enter the pod through an inlet (5a) of the airflow channel (5), is guided through the porous wick (2) and/or along a surface of the porous wick (2) and exits the pod (1) through an outlet of the airflow channel (5). The design and position of the airflow channel (5) is not particularly limited. It may, for instance, be centered in the pod and have a tubular shape, wherein the porous wick (2), usually having a rod shape, is centered in the air flow channel (5), thereby forming two separate open areas (12) between two opposite sidewall surfaces (2a) of the porous wick (2) and the wall of the air flow channel (5), respectively. In this design, air may flow from the airflow inlet (5a) through the porous wick (2) and/or along a sidewall surface (2a) of the porous wick (2) facing the wall of the tubular airflow channel (5) to the airflow outlet (5b), i.e. from the bottom to the top as shown in e.g.
When the pod (1) of the present invention is in use, the vaporized e-liquid is mixed with the air that is guided through the porous wick (2) or along a surface of the porous wick (2) and is simultaneously discharged with the air through the outlet (5b) of the airflow channel (5). When the airflow channel (5) is configured so that air is guided along a surface of the porous wick (2), a heat transfer material layer (8) can be arranged adjacent to the surface of the porous wick (2) along which the air is guided to enhance heat supply to the porous wick (2) and reduce the time of commissioning.
The aerosol-generating device (10) of the present invention comprises the pod (1) according to the invention and a heater unit (11). When the aerosol-generating device (10) is used, the heater unit (11) distributes heat to the porous wick (2) and the temperature-switchable material (6) of the pod (1), thus initiating the temperature-induced wettability change of the temperature-switchable material (6). The heater unit (11) can be provided separately from the pod (1) in a heater-in-device configuration or can be provided integrally with the pod (1).
Embodiments of the invention will now be explained in detail, by way of non-limiting example only, with reference to the accompanying figures.
Where technical features in the drawings, detailed description or any claim are followed by reference signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the drawings, detailed description, and claims. Accordingly, neither the reference signs nor their absence have any limiting effect on the scope of any claim elements. The same reference signs listed in different figures refer to identical, corresponding or functionally similar elements.
When the pod (1) according to the embodiment as previously described with regard to
As shown in
When applying heat to the temperature-switchable wick (6) during use of the pod (1) of option (iii) as described with regard to
Although detailed embodiments have been described, these only serve to provide a better understanding of the invention defined by the independent claims and are not to be seen as limiting.
It will also be appreciated that the terms “comprise”, “comprising”, “include”, “including”, “contain”, “containing”, “have”, “having”, and any variations thereof as used herein, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the product and device described herein is not limited to those features recited but may include other elements or features not expressly listed or inherent to such product or device. Furthermore, the terms “a” and “an” used herein are intended to be understood as meaning one or more unless explicitly stated otherwise.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21205536.2 | Oct 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/080073 | 10/27/2022 | WO |
