Heater assembly containing polymer composite material for use in aerosol generation systems

Abstract

A heater assembly (212) for an aerosol generator is provided, comprising a heating body configured for resistance heating, wherein the heating body comprises a polymer composite material including a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

Description

Technical Field

[0001] The present disclosure relates to a heater assembly for an aerosol generating device. The present disclosure also relates to an aerosol generating device comprising the heater assembly, and to an aerosol generating system comprising the aerosol generating device and an aerosol generating article for use with the aerosol generating device.

Background Art

[0002] In particular, the present disclosure relates to a heater assembly comprising an electrical resistor configured to heat an aerosol generating substrate of an aerosol generating article.

[0003] Aerosol generating articles in which an aerosol forming substrate, such as a tobacco-containing substrate, is heated rather than burned are known in the art. Typically, in such aerosol generating articles, the aerosol is generated by the transfer of heat from a heat source to the aerosol forming substrate.

[0004] For example, an electrically operated aerosol generating device, such as a handheld aerosol generating device, can be used with such aerosol generating articles. Such an electrically operated aerosol generating device can comprise a heating element configured to heat the aerosol forming substrate to a temperature of several hundred degrees Celsius. Thereby, volatile compounds entrained in the air drawn through the aerosol generating article are released from the aerosol forming substrate. As the released compounds cool, they condense or nucleate to form an aerosol.

[0005] Several embodiments of aerosol generators for consuming aerosol-generating articles have been disclosed in the Art. Such a device may include, for example, an electrically heated aerosol generator in which an aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generator to the aerosol-generating elements of the aerosol-generating article. For this purpose, the aerosol-generating article may be partially received within a heated cavity of the aerosol generator, so that the upstream end of the aerosol-generating article is inserted into the cavity, while the downstream end of the aerosol-generating article protrudes out of the cavity.

[0006] For example, an electrically heated aerosol generator has been proposed that includes an internal heater blade adapted to be inserted into an aerosol generating substrate when an aerosol generating article is received in a heated cavity. Alternatively, heating of the aerosol generating substrate is achieved using external heating, such as by a tubular heater element that at least partially defines a heated cavity into which an aerosol generating article is inserted, or is coupled in a different manner to a tubular element that defines the heated cavity.

[0007] Induction-heated aerosol generating articles have been proposed, for example, in WO2015 / 176898. These aerosol generating articles comprise an aerosol generating element comprising an aerosol generating substrate, such as a tobacco-containing substrate, and a susceptor disposed within the aerosol generating substrate. Functional coupling between the susceptor and the induction heater element of the aerosol generating device is achieved when the aerosol generating article is partially received within the heating cavity of the aerosol generating device.

[0008] Constructing heater elements for externally heating an aerosol-generating substrate tends to be a fairly complex process, typically involving imparting a curved or tubular shape to an originally flat heating film. For example, an originally flat heating film may need to be wrapped around a mandrel or a tube with a relatively small radius of curvature. This operation can be particularly complex because the heating film may be formed from multiple layers of materials with different flexibility. The manufacturing process can be further complicated by the need to incorporate multiple separate heating units within a single aerosol generator, in terms of providing different modes of heating the aerosol-generating substrate.

[0009] Solid aerosol generating substrates need to be heated to a temperature sufficient to facilitate the extraction of aerosol species (e.g., nicotine and glycerin). Existing heaters are typically configured to supply heat so that the solid aerosol generating substrate is exposed to temperatures within this range throughout. However, this heating setting may have the disadvantage of being less battery efficient in use. Furthermore, this heating setting may limit the use of the solid aerosol generating substrate to a predetermined number of puffs, a finite number of puffs, or a predetermined number of minutes. Moreover, maintaining the solid aerosol generating substrate at a temperature sufficient to facilitate the extraction of aerosol species between puffs may also undesirably increase the risk of generating harmful and potentially harmful components (HPHCs).

[0010] It would be desirable to provide a heater assembly for an aerosol generator adapted to address at least partially one of the aforementioned drawbacks. For example, it would be desirable to provide a novel and improved heater assembly for an aerosol generator that is easier to manufacture. Similarly, it would be desirable to provide a novel and improved aerosol generator comprising a heater assembly that can be configured to provide more efficient external heating of a solid aerosol generating substrate. [Overview of the project]

[0011] This disclosure relates to a heater assembly for an aerosol generator.

[0012] The heater assembly may include a heating body configured for resistance heating.

[0013] The heating element may contain a polymer composite material.

[0014] The polymer composite material may include a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

[0015] According to a first aspect of the present invention, a heater assembly for an aerosol generator is provided, comprising a heating body configured for resistance heating, wherein the heating body comprises a polymer composite material including a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

[0016] According to a second aspect of the present invention, an aerosol generator is provided that includes a heater assembly according to the first aspect of the present invention.

[0017] According to a third aspect of the present invention, an aerosol generating system is provided, comprising an aerosol generating device according to a second aspect of the present invention and an aerosol generating article for use in the aerosol generating device.

[0018] In contrast to existing heater assemblies for aerosol generators, the heater assembly according to the present invention comprises a heating body configured for resistance heating, the heating body comprising a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

[0019] The inventors found that a heating body comprising a polymer matrix and at least one filler particle dispersed within the polymer matrix, consisting of graphite, graphite-derived material, and hexagonal boron nitride, is generally easier to manufacture than similar heating bodies configured for resistance heating, which are typically made of other conductive materials used in existing heater assemblies for aerosol generators.

[0020] More specifically, the inventors observed that the thermoplastic properties of the polymer matrix allow the polymer composite to be conveniently made malleable, making it suitable for precise and controlled molding. In particular, this makes it easier to form the polymer composite described above into elongated hollow shapes, compared to conductive materials typically used in heater assemblies of existing aerosol generators.

[0021] At the same time, by controlling and adjusting the concentration and distribution of conductive filler particles dispersed in the polymer matrix, it is advantageous to provide a heating body that can generate sufficient heat by the Joule effect to efficiently heat the solid aerosol generating substrate of an aerosol generating article thermally bonded to the heating body.

[0022] While not wishing to be bound by theory, the inventors have found that conductivity, and consequently, the amount of heat resistively generated by the heater assembly when a voltage is applied to the heating body, can be controlled by adjusting the formulation of the polymer matrix and the degree of dispersion of conductive filler particles within the polymer matrix. In particular, as will be discussed in more detail below, it may be advantageously possible to ensure that a heating body made of polymer composite material exhibits a very desirable level of resistivity by adjusting the relative ratio of conductive filler to polymer within the polymer composite material. Other parameters, such as the length and cross-sectional area of ​​the heating body, may also be varied to fine-tune the resistive behavior of the heating body as a whole. Generally, this provides an enhanced ability to control and improve the efficiency of heat transfer from the heater assembly to the aerosol generating substrate, which may also be beneficially advantageous for more effective extraction of aerosol species from the substrate itself.

[0023] Therefore, a heater assembly having the features described above is advantageously used in an aerosol generator that forms part of an aerosol generation system, where the elongated aerosol generating article is at least partially received within the heating chamber of the heating body. This ensures that the aerosol generating substrate of the aerosol generating article is thermally coupled with the heating body, and that heat can be efficiently transferred from the heater assembly to the aerosol generating substrate.

[0024] Furthermore, the inventors identified favorable processing conditions under which a porous heating body containing a polymer composite can be formed with desirable porosity values, average pore size, and specific surface area. Such a porous heating body can be advantageously found to be used in heater assemblies of aerosol generators, configured to be drawn into the aerosol generator before reaching the aerosol generating substrate during use and to convectively supply heat to the air flowing through the porous heating body.

[0025] In practice, such a porous heating body may be configured to convectively transfer heat to the air flow drawn into the aerosol generating device so that the air flow is preheated before reaching the aerosol generating substrate. This can be beneficial in that the aerosol-forming species present in the aerosol generating substrate can be released more efficiently upon heating.

[0026] Furthermore, since the supply of heat to the incoming air flow can be combined with the supply of heat from a further independently controlled heat source, different from the porous heating body, to the aerosol generating substrate, it may generally be possible to supply and exchange heat more efficiently during use of the aerosol generating device. By operating and controlling independently the supply of heat from the porous heating body and the further heat source, it may advantageously be possible to manage more efficiently the overall supply of heat to the aerosol generating article during use, for example, to reduce the heat consumption during successive puffs.

[0027] Without wishing to be bound by theory, it is understood that the residence time of air, i.e., the average time taken by a population of fluid within the control volume in the porous body, is a function of the porosity and tortuosity of the porous body, as well as its geometric shape. The porosity, average pore size and pore size distribution, and the specific surface area of the porous body will also affect the amount of heat convectively exchanged. At the same time, the porosity and tortuosity of the porous body affect the pull resistance (RTD) of the porous body and the heating body as a whole. By adjusting the porosity, length, and diameter of the porous body, a satisfactory balance can be achieved between the ability to efficiently preheat the air flowing through the porous body and the RTD of the porous body.

[0028] Thus, for example, the porous body of the heater assembly according to the present invention can be configured to preheat a certain volume of air substantially corresponding to the average volume inhaled by the consumer with each puff to a predetermined temperature. By ensuring that the flow of air entering in such a preheated state reaches the aerosol generation substrate, the amount of heat supplied to the aerosol generation substrate can be advantageously reduced via an additional heat source.

[0029] As a result, the additional heat source can be configured to reach an average relatively lower temperature during use. Therefore, the overall energy consumption is reduced. At the same time, by maintaining the aerosol generation substrate at a relatively lower temperature in the smoking chamber, more efficient use of the aerosol generation substrate may be enabled to optimize the delivery of aerosol species to the consumer over a longer period.

[0030] For example, the additional heat source may be configured to heat the aerosol generation substrate of the aerosol generating article to a standby temperature or a holding temperature during a use session. The aerosol generating device comprising the heater assembly described above can be further configured such that when the user smokes, the temperature of the aerosol generation substrate rises from the standby temperature to, for example, an operating temperature.

[0031] For example, the aerosol generating device can be configured to supply a heat boost to the aerosol generation substrate during user smoking that occurs during a use session. For this purpose, the aerosol generating device may depend on the heater assembly according to the present invention, and the heater assembly comprises a porous heating body of the type briefly described above.

[0032] As will be discussed in more detail below, the porous heating body can define an airflow path upstream of the cavity into which the aerosol-generating article is at least partially received. When using the device, the user draws air into the aerosol generator through the airflow path, which can connect the cavity to the external environment. Thus, the air flowing along the airflow path through the porous heating body is heated before reaching the cavity, where it provides a thermal boost to the aerosol-generating substrate of the aerosol-generating article.

[0033] With this configuration, the aerosol generating substrate can be maintained at a first temperature, for example, a standby temperature (i.e., a temperature that is or slightly below the temperature required to form an aerosol), and then heated to an increased temperature, for example, an operating temperature (i.e., a temperature that is above the temperature required to form an aerosol during the user's inhalation).

[0034] The standby target temperature is preferably higher than room temperature, and the operating target temperature is higher than the standby target temperature. By selecting an appropriate standby temperature, the aerosol-forming substrate can be boosted to the operating temperature almost instantaneously based on the application of further thermal energy to the substrate. After user inhalation, the temperature can be lowered to the standby temperature.

[0035] The combination of heating to standby temperature and rapid temperature rise to operating temperature during inhalation allows for efficient acquisition of desirable components of the aerosol generating substrate, such as nicotine, flavor components, and aerosol-forming substances like glycerin, without overheating the aerosol generating substrate over a wide area. The formation of undesirable aerosol components can be reduced, and optimal acquisition of desirable components can be achieved.

[0036] To implement such a configuration, the aerosol generator is preferably equipped with at least a flow detector, for example, in the form of a pressure sensor.

[0037] A flow detector may be used to control the power supply to the heating body. For example, a flow detector may be used to selectively power the permeable body portion of the heating body so that, only during fume extraction, the permeable body portion generates and transfers sufficient heat to the incoming airflow to further boost the temperature of the aerosol generating substrate downstream.

[0038] However, the heater assembly may also be configured to continuously supply power to the ventilated body portion during a usage session, so that the incoming airflow associated with smoke extraction is instantaneously heated without the need for smoke extraction detection. The heater assembly may also be configured to consistently heat to a standby temperature upon smoke extraction detection, and then supply power to the ventilated body portion, which may help to take a position contrary to the fact that the incoming airflow typically cools the ventilated body portion when it flows through it.

[0039] Therefore, an aerosol generator equipped with a heater assembly according to the present invention, wherein the heater assembly comprises a porous heating body of the type briefly described above, can be configured to control the temperature of the aerosol generating substrate with respect to a standby target temperature during non-fumigation periods and to an operating target temperature during fumigation periods. As a result, during non-fumigation periods, the substrate temperature is consistently maintained at the standby target temperature. Once the start of user fumigation is detected, the temperature rises to the operating target temperature, and after user fumigation ends, the temperature drops again to the standby target temperature.

[0040] As used herein in connection with the present invention, the term "aerosol-generating article" is used to describe an article comprising an aerosol-generating substrate that generates and delivers a heated, inhalable aerosol to a user.

[0041] As used herein in connection with the present invention, the term "aerosol-generating substrate" is used to describe a substrate comprising an aerosol-generating material that can release an aerosol in response to heating of a volatile compound capable of generating an aerosol.

[0042] As used herein in connection with the present invention, the term "aerosol" is used to describe a dispersion of solid particles or droplets, or a combination of solid particles and droplets, in a gas. Aerosols may be visible or invisible. Aerosols may include not only vapors of substances that are normally liquid or solid at room temperature, but also solid particles or droplets, or a combination of solid particles and droplets.

[0043] As used herein in connection with the present invention, the term "aerosol generator" is used to describe a device that generates an aerosol by interacting with an aerosol-generating substrate of an aerosol-generating article.

[0044] As used herein, the terms “distal,” “upstream,” “proximal,” and “downstream” describe the relative positions of components or parts of components of an aerosol generating device and an aerosol generating article. The aerosol generating articles and devices relating to this disclosure have a proximal end through which aerosols exit the article or device for delivery to the user, and a distal end on the opposite side. The proximal end of the aerosol generating article and device may also be referred to as the mouth end. During use, the user inhales at the proximal end of the aerosol generating article to inhale the aerosol generated by the aerosol generating article or device. The terms upstream and downstream relate to the direction of movement of aerosols through the aerosol generating article or aerosol generating device when the user inhales at the proximal end of the aerosol generating article. The proximal end of the aerosol generating article is downstream of the distal end of the aerosol generating article. The proximal end of the aerosol generating article may also be referred to as the downstream end of the aerosol generating article, and the distal end of the aerosol generating article may also be referred to as the upstream end of the aerosol generating article.

[0045] As used herein in connection with the present invention, the terms “long axis direction” and “axial direction” are used to describe the direction between the upstream and downstream ends of an aerosol generating article, or between the upstream and downstream ends of an aerosol generating device. During use, air is drawn through the aerosol generating article in the long axis direction.

[0046] As used herein, the term "length" is used to describe the maximum dimension of an aerosol generating article or aerosol generating device or a component of an aerosol generating article or aerosol generating device in the longitudinal direction.

[0047] As used herein in connection with the present invention, the term “transverse direction” is used to describe a direction perpendicular to the longitudinal axis. Unless otherwise stated, any reference to “cross section” of an aerosol generating article or aerosol generating device or a component of an aerosol generating article or aerosol generating device refers to a transverse section.

[0048] As used herein in connection with the present invention, the term "width" refers to the maximum transverse dimension of an aerosol generating article or apparatus or a component of an aerosol generating article or apparatus. If the aerosol generating article has a substantially circular cross-section, the width of the aerosol generating article corresponds to the diameter of the aerosol generating article. If the components of the aerosol generating article have a substantially circular cross-section, the width of the components of the aerosol generating article corresponds substantially to the diameter of the components of the aerosol generating article.

[0049] As used herein in connection with the present invention, the term “hollow tubular element” is used to describe a substantially cylindrical element having a lumen along its longitudinal axis. The tubular portion may have a substantially circular, oval, or elliptical cross-section. The lumen may have a substantially circular, oval, or elliptical cross-section. Specifically, the term “hollow tubular element” is used to describe an element that defines at least one airflow conduit establishing an uninterrupted fluid communication between the upstream end of the hollow tubular element and the downstream end of the hollow tubular element.

[0050] As used herein, the term "heating body" refers to a component configured to transfer thermal energy to an aerosol generating substrate.

[0051] As used herein, the term “permeable” is used to describe an entity through which air can pass. The term “permeable” also encompasses the capacity properties of a suitable material, for example, a material having porosity in all or part of its capacity.

[0052] Therefore, as used herein in connection with the present invention, the term “permeable body portion” refers to a segment of material that is not blocked, blocked, or sealed in such a manner as to completely block air from passing through the permeable body portion.

[0053] The permeable body portion may be configured to allow airflow along a desired airflow direction. For example, the permeable body portion may be configured to allow airflow from a first end of the permeable body portion to a second end of the permeable body portion that is opposed to the first end of the permeable body portion in the longitudinal direction.

[0054] To enable flow along a desired airflow direction, the permeable body portion may include one or more airflow channels extending through the permeable body portion. For example, the permeable body portion may include one or more airflow channels extending from a first end of the permeable body portion to a second end of the permeable body portion opposite to the first end of the permeable body portion.

[0055] One or more airflow channels in a permeable body may be arranged within the permeable body in a regular and orderly manner. For example, a permeable body may define multiple substantially longitudinal airflow channels extending parallel to each other. In particular, a permeable body may have a honeycomb structure. The void ratio and cross-sectional void ratio of such a permeable body can be easily defined and controlled by adjusting the number and size of airflow channels within the honeycomb structure.

[0056] The permeable body portion may otherwise define one or more airflow channels in an irregular and substantially disorderly manner. For example, the permeable body portion may be a porous portion. As used herein, the term “porous portion” refers to a portion of the body having multiple pores, at least some of which are interconnected. Thus, the porous portion of the body can generally define airflow paths through the porous portion so that fluid can flow from one end face of the porous portion to a second end face of the porous portion opposite the first end face. Generally, the pressure drop across a porous portion will be greater than the pressure drop across a hollow tubular element of the same length and with a free cross-sectional area equal to the overall cross-sectional area of ​​the porous portion. Thus, the flow across a porous portion is generally partially restricted compared to the flow through a hollow tubular element of comparable dimensions.

[0057] The term "porosity" in the context of the main body generally refers to the ratio of the volume of accessible pores and voids to the bulk volume occupied by the main body. The term "cross-sectional porosity" refers to the void ratio in the cross-sectional area of ​​a permeable main body, particularly the cross-section of a porous body such as the cross-section of the permeable main body portion of the heating body of the heater assembly according to the present invention.

[0058] The cross-sectional porosity is the ratio of the void area in the cross-sectional area of ​​the permeable body. The cross-sectional area of ​​the permeable body portion is the area of ​​the permeable body portion in a plane perpendicular to the desired airflow direction. In particular, referring to a permeable body portion extending along the longitudinal axis, the cross-sectional area of ​​the permeable body portion can generally be the area of ​​the permeable body portion in a plane perpendicular to the longitudinal axis of the permeable body portion, which is also the longitudinal axis of the heater assembly and the longitudinal axis of the aerosol generator equipped with the heater assembly.

[0059] Porous materials are typically substantially cylindrical, and therefore their cross-sections are substantially circular. However, more generally, it is possible to identify the longitudinal axis of a porous material, and the cross-section of the porous material lies in a plane substantially perpendicular to the aforementioned longitudinal axis.

[0060] For example, the value of the cross-sectional porosity can be determined using a digital image processing process. A digital image of the cross-section of a porous material can be obtained, and a threshold can be applied to distinguish pixels representing solid material from pixels representing voids. The porosity ratio of the entire cross-section can then be easily obtained. For example, referring to the porous portion of the heating body of a heater assembly according to the present invention, whose features are described in more detail below, a suitable image of the cross-section of the porous portion can be obtained by X-ray microscopy.

[0061] As used herein in relation to the present invention, the term "specific surface area" is used to refer to the total surface area of ​​a solid material per unit mass. Specific surface area generally depends on the size of the particles forming the solid material, as well as the structure and porosity and void size distribution of the solid material.

[0062] Unless otherwise specified, the draw resistance (RTD) of a component or aerosol-generating article is measured according to ISO 6565:2002. RTD refers to the pressure required to pump air through the entire length of the component. The terms “pressure drop” or “draw resistance” for a component or article may also refer to “resistance to draw.” Such terms generally refer to measurements performed according to ISO 6565:2002, typically at a temperature of approximately 22 degrees Celsius, a pressure of approximately 101 kPa (approximately 760 Torr), and a relative humidity of approximately 60%, with a volumetric flow rate of approximately 17.5 milliliters per second at the output or downstream end of the component being measured. When measurements are performed, any ventilation openings present within the component or aerosol-generating article are sealed. In operation for aerosol consumption or inhalation by the user, the static pressure difference between the two ends of the aerosol generating article received in the receiving cavity of the aerosol generator may be in the range of 10 to 150 mmH2O, more preferably 20 to 140 mmH2O, and even more preferably 30 to 120 mmH2O.

[0063] As briefly described above, the heater assembly for an aerosol generator according to the present invention comprises a heating body configured for resistance heating. Resistance heating, also known as Joule heating, is a process in which the passage of an electric current through a conductive body generates heat. Generally, the heat released per second (i.e., the generated heat output) is equal to the square of the current multiplied by the resistance of the conductive body.

[0064] More specifically, in a heater assembly according to a first aspect of the present invention, the heating body includes a polymer composite material comprising a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

[0065] The heating unit may include a breathable body portion that defines an airflow path through the breathable body portion.

[0066] The breathable main body portion may also be a porous material portion.

[0067] The heating body may include a hollow tubular body portion that defines a chamber having an open end for receiving at least a portion of the aerosol-generating article.

[0068] In some embodiments, the heating body comprises both a permeable body portion defining an airflow path through a permeable body portion and a hollow tubular body portion defining a chamber having an open end for receiving at least a portion of an aerosol-generating article, wherein the airflow path is upstream of the chamber and is in fluid communication with it. In these embodiments, it is preferable that the equivalent free cross-sectional area of ​​the airflow path is smaller than the free cross-sectional area of ​​the chamber.

[0069] By providing a permeable body portion located upstream of the tubular chamber and defining an airflow path in fluid communication with it, the advantage is that the permeable body portion can be used to convectively heat the incoming airflow before it reaches the aerosol generating substrate of the aerosol generating article at least partially received in the tubular chamber. Thus, the airflow reaches the aerosol generating substrate in a preheated state.

[0070] In some preferred embodiments, the heater assembly comprises a covering on the exposed surface of the airflow path defined by the permeable body portion. The covering may be a protective covering. The covering may be a thermally conductive covering. The covering may be disposed on the exposed surface of the permeable body portion so as to advantageously prevent the potential release of material from the permeable body portion into the airflow path. During use, the protective layer advantageously provides a separation between the material forming the permeable body portion and the air flowing through the permeable body portion and then further downstream to the aerosol generating substrate received in the tubular chamber. In particular, the protective layer forms a "skin" that can prevent the accidental release of any conductive material (such as graphite) from the polymer composite into the airflow path. Furthermore, the covering can improve heat transfer from the heater assembly to the aerosol generating article.

[0071] For example, a heater assembly with a breathable body may be immersed in a bath containing a protective coating formulation or protective coating precursor. Thus, all internal cavities, ducts, and channels that define airflow paths can be conveniently accessed, and their surfaces can be covered with the protective coating.

[0072] In a preferred embodiment, an aerosol generator comprising a heater assembly having a breathable body portion as described above, is configured to heat the aerosol generating substrate of an aerosol generating article during a usage session, with reference to two different target temperatures: a standby or maintenance target temperature and an operating target temperature.

[0073] The aerosol generator is more preferably configured to supply a thermal boost to the aerosol generating substrate during user inhalation performed during a usage session. In particular, the heater assembly is preferably configured such that, when the user draws air into the aerosol generator through the airflow path during a usage session, the air flowing along the airflow path through the permeable body portion is heated before it reaches the chamber of the hollow tubular body portion, and the aerosol generating article is at least partially received. This is such that once the air heated by the porous heating body reaches the chamber of the hollow tubular body portion, it can convectively supply a thermal boost to the aerosol generating substrate of the aerosol generating article.

[0074] Advantageously, this allows the aerosol generator to be configured such that the aerosol generating substrate is maintained at a first temperature, for example, a standby temperature (i.e., the temperature required to form an aerosol, or slightly lower), and then heated to an increased temperature, for example, an operating temperature (i.e., a temperature higher than the temperature required to form an aerosol during the user's inhalation). The standby target temperature is preferably higher than room temperature, and the operating target temperature is higher than the standby target temperature.

[0075] The standby target temperature is preferably too low to release substantial aerosols from the aerosol-forming substrate. In other words, the standby temperature may be below the effective aerosolization temperature of the substrate. For example, the standby target temperature may be lower than the vaporization temperature or effective boiling point of the aerosol-forming material or mixture of aerosol-forming materials in the aerosol-forming substrate. For example, the standby target temperature may be set lower than the boiling point of propylene glycol, or lower than the boiling point of glycerol, or lower than the boiling point of a particular mixture of propylene glycol and glycerol used as an aerosol-forming material in the aerosol-forming substrate. The standby temperature may alternatively be referred to as the maintenance temperature.

[0076] The standby target temperature may be less than 250 degrees Celsius, for example less than 230 degrees Celsius, for example less than 210 degrees Celsius, preferably less than 200 degrees Celsius, for example less than 180 degrees Celsius, or less than 160 degrees Celsius. The standby target temperature may also be between 50 degrees Celsius and 250 degrees Celsius, for example between 80 degrees Celsius and 200 degrees Celsius, for example between 100 degrees Celsius and 180 degrees Celsius.

[0077] The target operating temperature is preferably high enough to release aerosols from the aerosol-forming substrate. In other words, the operating temperature may exceed the effective aerosolization temperature of the substrate. For example, the target operating temperature may be higher than the effective boiling point of the aerosol-forming material or mixture of aerosol-forming materials in the aerosol-forming substrate, e.g., higher than the boiling point of propylene glycol, or higher than the boiling point of glycerol, or higher than the boiling point of a particular mixture of propylene glycol and glycerol used as the aerosol-forming material in the aerosol-forming substrate.

[0078] The target operating temperature may be above 160 degrees Celsius, for example above 180 degrees Celsius, or above 200 degrees Celsius, or above 250 degrees Celsius, for example above 280 degrees Celsius, or above 300 degrees Celsius, or above 320 degrees Celsius, or above 340 degrees Celsius. The target standby temperature may be between 160 degrees Celsius and 400 degrees Celsius, for example between 180 degrees Celsius and 340 degrees Celsius, for example between 220 degrees Celsius and 300 degrees Celsius.

[0079] Because the temperature of the aerosol-generating substrate is substantially maintained at the standby temperature between inhalations and rapidly rises to the operating temperature during inhalation, desirable components of the aerosol-generating substrate, such as nicotine, flavor components, and aerosol-forming substances like glycerin, can be efficiently obtained without extensive overheating of the substrate. This has the advantage that the formation of undesirable aerosol components can be reduced or prevented, while at the same time, optimal acquisition of desirable components can be achieved.

[0080] The standby target temperature may remain constant throughout the entire duration of the usage session. Alternatively, the standby target temperature may vary over the duration of the usage session. That is, the standby target temperature may evolve over the course of the usage session to account for the depletion of aerosol-forming components as the user inhales during the usage session.

[0081] The target operating temperature may remain constant throughout the entire duration of the usage session. Alternatively, the target operating temperature may vary over the duration of the usage session. The target operating temperature may vary with each smoke extraction. Variations in the target operating temperature, for example, an increase in the target operating temperature, may help optimize aerosol delivery from the aerosol-forming substrate as the aerosol-forming components are depleted during the course of the usage session. In an aerosol generator comprising a heater assembly with a permeable body portion configured as described above, at least a flow detector, for example in the form of a pressure sensor, is provided to control the temperature to either the standby target temperature or the operating target temperature. The flow detector may be located in fluid communication with the airflow path through the permeable body portion. Signals from the flow detector may be used to detect one or more user smoke extractions performed during the usage session.

[0082] For example, the device may be configured to detect one or more user inhalations performed during a usage session. Preferably, the device is configured to detect the start of each user inhalation performed during a usage session, for example. Preferably, the device is configured to detect the end of each user inhalation performed during a usage session, for example. Therefore, the device may be configured to determine the duration of each user inhalation performed during a usage session, for example. In some preferred embodiments, the permeable body portion is at least partially disposed within the hollow tubular body portion of the heating body. Preferably, the permeable body portion is substantially integrated with the hollow tubular body portion of the heating body.

[0083] This configuration offers many advantages from a manufacturing standpoint, as it can be advantageous to form a permeable porous body portion by sintering a predetermined amount of polymer composite particles, for example, arranged to form a plug at one end of a hollow tubular body portion. By controlling the particle size and selecting appropriate sintering temperatures and durations, it is advantageous to form a porous body portion integrated with the hollow tubular body portion, while ensuring that the porous body portion has desirable values ​​such as total pore volume, average pore size, and specific surface area.

[0084] Furthermore, by providing at least partially a breathable body portion within the hollow tubular body portion of the heating unit, a compact configuration becomes possible, and different functionalities can be combined in a relatively small volume.

[0085] The length of the breathable body portion may be at least 1 millimeter. Preferably, the length of the breathable body portion is at least 1.5 millimeters. More preferably, the length of the breathable body portion is at least 2 millimeters. Even more preferably, the length of the breathable body portion is at least 2.5 millimeters.

[0086] In some embodiments, the length of the breathable body portion may be up to 10 millimeters. Preferably, the length of the breathable body portion is 8 millimeters or less. More preferably, the length of the breathable body portion is 6 millimeters or less. Even more preferably, the length of the breathable body portion is 5 millimeters or less.

[0087] In some embodiments, the length of the breathable body portion is 1 mm to 10 mm, preferably 1.5 mm to 10 mm, more preferably 2 mm to 10 mm, and even more preferably 2.5 mm to 10 mm.

[0088] For example, the length of the breathable main body portion is 1 mm to 8 mm, preferably 1.5 mm to 8 mm, more preferably 2 mm to 8 mm, and even more preferably 2.5 mm to 8 mm.

[0089] For example, the length of the breathable main body portion is 1 mm to 6 mm, preferably 1.5 mm to 6 mm, more preferably 2 mm to 6 mm, and even more preferably 2.5 mm to 6 mm.

[0090] For example, the length of the breathable main body portion is 1 mm to 5 mm, preferably 1.5 mm to 5 mm, more preferably 2 mm to 5 mm, and even more preferably 2.5 mm to 5 mm.

[0091] The outer diameter of the breathable body portion may be at least 4 millimeters. Preferably, the outer diameter of the breathable body portion is at least 5 millimeters. More preferably, the outer diameter of the breathable body portion is at least 6 millimeters.

[0092] In some embodiments, the outer diameter of the breathable body portion may be up to 12 millimeters. Preferably, the outer diameter of the breathable body portion is 10 millimeters or less. More preferably, the outer diameter of the breathable body portion is 8 millimeters or less.

[0093] For example, the outer diameter of the breathable main body is 4 mm to 12 mm, preferably 5 mm to 12 mm, and more preferably 6 mm to 12 mm.

[0094] For example, the outer diameter of the breathable main body portion is 4 mm to 10 mm, preferably 5 mm to 10 mm, and more preferably 6 mm to 10 mm.

[0095] For example, the outer diameter of the breathable main body portion is 4 mm to 8 mm, preferably 5 mm to 8 mm, and more preferably 6 mm to 8 mm.

[0096] The breathable body portion preferably contains at least 50 weight percent of polymer composite material. More preferably, the breathable body portion contains at least 60 weight percent of polymer composite material. Even more preferably, the breathable body portion contains at least 75 weight percent of polymer composite material. In a particularly preferred embodiment, the breathable body portion contains at least 90 weight percent of polymer composite material, preferably at least 95 weight percent of polymer composite material. In a specific embodiment, the breathable body portion is entirely made of polymer composite material.

[0097] When the main body of a permeable structure is primarily made of polymer composites, it is advantageous that it is easier to control the characteristics of the permeable structure, such as resistivity and porosity, which will have some effect on heat generation and heat transfer during use. In particular, forming the permeable structure substantially entirely from polymer composites is advantageous from a manufacturing standpoint, as it is easier to ensure that properties such as density, porosity, and resistivity are substantially homogeneous throughout the permeable structure.

[0098] In certain embodiments, the permeable body portion is provided in the form of a porous portion formed by sintering particles of a polymer composite material. Sintering is a process by which matching particles of a particular material are heated to a temperature higher than the firing temperature of the material and compressed to form a solid without melting the material to its liquefaction point. In practice, sintering involves the diffusion of atoms across the boundaries between adjacent particles of the material so that adjacent particles fuse together in a single part.

[0099] The temperature and duration of the sintering process can be selected to increase the strength and integrity of the resulting body, as higher temperatures and longer exposure to heat generally induce densification of the material. At the same time, the temperature and duration of the sintering process can be selected to maintain the desired porosity of the body at the end of the sintering process.

[0100] The particle size of the polymer composite material may be selected from the viewpoint of controlling the void ratio within the sintered porous portion to some extent.

[0101] In some embodiments, the porous portion may be sintered from polymer composite particles having an average diameter of at least 50 micrometers. Preferably, the porous portion is sintered from polymer composite particles having an average diameter of at least 100 micrometers. More preferably, the porous portion is sintered from polymer composite particles having an average diameter of at least 200 micrometers.

[0102] In some embodiments, the porous portion may be sintered from polymer composite particles having an average diameter of up to 1000 micrometers. Preferably, the porous portion is sintered from polymer composite particles having an average diameter of 800 micrometers or less. More preferably, the porous portion is sintered from polymer composite particles having an average diameter of 600 micrometers or less.

[0103] For example, the porous portion is sintered from polymer composite particles having an average diameter of 50 to 1000 micrometers, or 50 to 800 micrometers, or 50 to 600 micrometers, or 100 to 1000 micrometers, or 100 to 800 micrometers, or 100 to 600 micrometers, or 200 to 1000 micrometers, or 200 to 800 micrometers, or 200 to 600 micrometers.

[0104] Techniques other than sintering may be used to form porous portions. For example, a 3D printing process may be used, and the porous portion may consist of multiple linear elements formed from intersecting polymer composites, where each layer is formed layer by layer, and each layer ultimately forms a three-dimensional object with a void ratio that can be finely controlled by controlling how the polymer composite is dispensed throughout the 3D printing process. Additionally, or by other means, it may be possible to control the cross-sectional void ratio and RTD of the porous portion by adjusting the size of the nozzle from which the polymer composite is dispensed.

[0105] Alternatively, the permeable body portion, including the polymer composite, may be formed by extrusion. For example, the polymer composite may be extruded to form a permeable body portion having a honeycomb structure, i.e., a single permeable body portion defining a plurality of open channels extending substantially parallel to each other from a first end face of the permeable body portion to a second end face of the permeable body portion longitudinally opposite the first end face. Such a manufacturing process may, if desired, allow for easier and finer control over the parameters of the permeable body portion. For example, the number of open channels and the cross-sectional area of ​​each open channel may be selected to control the draw resistance and cross-sectional porosity of the permeable body portion. In addition, or otherwise, the length of the permeable body portion may be selected to control the draw resistance and the surface area available for heat exchange of the permeable body portion.

[0106] The cross-sectional void ratio of the breathable main body portion may be at least 15 percent. Preferably, the cross-sectional void ratio of the breathable main body portion is at least 20 percent. More preferably, the cross-sectional void ratio of the breathable main body portion is at least 25 percent.

[0107] The void ratio of the cross-sectional area of ​​the breathable main body is preferably 45 percent or less. The void ratio of the cross-sectional area of ​​the breathable main body is more preferably 40 percent or less. The void ratio of the cross-sectional area of ​​the breathable main body is even more preferably 35 percent or less.

[0108] For example, the void ratio in the cross-sectional area of ​​the breathable main body portion may be 15 percent to 45 percent, preferably 15 percent to 40 percent, and more preferably 15 percent to 35 percent.

[0109] For example, the void ratio of the cross-sectional portion of the breathable main body may be 20 percent to 45 percent, preferably 20 percent to 40 percent, and more preferably 20 percent to 35 percent.

[0110] For example, the void ratio of the cross-sectional portion of the breathable main body may be 25 percent to 45 percent, preferably 25 percent to 40 percent, and more preferably 25 percent to 35 percent.

[0111] It has been found that permeable body portions having cross-sectional porosity within the above-mentioned range are associated with particularly desirable RTD values. Furthermore, it has been found that values ​​of cross-sectional porosity within the above-mentioned range are associated with particularly desirable values ​​of specific surface area, and as a result, heat can be exchanged fairly efficiently between the permeable body portion and the airflow through the permeable body portion.

[0112] The total pore volume of the breathable main body portion may be at least 0.5 cubic centimeters. Preferably, the total pore volume of the breathable main body portion is at least 1 cubic centimeter. More preferably, the total pore volume of the breathable main body portion is at least 1.5 cubic centimeters. Even more preferably, the total pore volume of the breathable main body portion is at least 2 cubic centimeters.

[0113] The total pore volume of the breathable main body may be up to 5 cubic centimeters. Preferably, the total pore volume of the breathable main body is 4.5 cubic centimeters or less. More preferably, the total pore volume of the breathable main body is 4 cubic centimeters or less. Even more preferably, the total pore volume of the breathable main body is 3.5 cubic centimeters or less.

[0114] For example, the total pore volume of the breathable main body may be 0.5 cubic centimeters to 5 cubic centimeters, preferably 1 cubic centimeter to 5 cubic centimeters, more preferably 1.5 cubic centimeters to 5 cubic centimeters, and even more preferably 2 cubic centimeters to 5 cubic centimeters.

[0115] For example, the total pore volume of the breathable main body may be 0.5 cubic centimeters to 4.5 cubic centimeters, preferably 1 cubic centimeter to 4.5 cubic centimeters, more preferably 1.5 cubic centimeters to 4.5 cubic centimeters, and even more preferably 2 cubic centimeters to 4.5 cubic centimeters.

[0116] For example, the total pore volume of the breathable main body may be 0.5 cubic centimeters to 4 cubic centimeters, preferably 1 cubic centimeter to 4 cubic centimeters, more preferably 1.5 cubic centimeters to 4 cubic centimeters, and even more preferably 2 cubic centimeters to 4 cubic centimeters.

[0117] For example, the total pore volume of the breathable main body may be 0.5 cubic centimeters to 3.5 cubic centimeters, preferably 1 cubic centimeter to 3.5 cubic centimeters, more preferably 1.5 cubic centimeters to 3.5 cubic centimeters, and even more preferably 2 cubic centimeters to 3.5 cubic centimeters.

[0118] The permeable body portion may be configured to hold an air volume corresponding to a portion of the smoke absorption, or even to the entire smoke absorption (up to 75 milliliters or more). This is advantageous as it may allow preheating of the air volume corresponding to a portion or the entire smoke absorption. To be able to hold an air volume corresponding to the entire smoke absorption volume, the total pore volume of the porous body is quite large. In some embodiments, the total pore volume of the permeable body portion may be at least 10 cubic centimeters. Preferably, the total pore volume of the permeable body portion is at least 20 cubic centimeters. More preferably, the total pore volume of the permeable body portion is at least 30 cubic centimeters. Even more preferably, the total pore volume of the permeable body portion is at least 40 cubic centimeters.

[0119] The total volume of pores in the breathable main body may be up to 80 cubic centimeters, preferably 70 cubic centimeters or less, and more preferably 60 cubic centimeters or less.

[0120] In some embodiments, the total pore volume of the permeable body portion is 10 to 80 cubic centimeters, preferably 10 to 70 cubic centimeters, and more preferably 10 to 60 cubic centimeters.

[0121] In other embodiments, the total pore volume of the permeable body portion is 20 to 80 cubic centimeters, preferably 20 to 70 cubic centimeters, and more preferably 20 to 60 cubic centimeters.

[0122] In further embodiments, the total pore volume of the permeable body portion is 30 cubic centimeters to 80 cubic centimeters, preferably 30 cubic centimeters to 70 cubic centimeters, and more preferably 30 cubic centimeters to 60 cubic centimeters.

[0123] In a particular embodiment, the total pore volume of the breathable body portion is 40 cubic centimeters to 80 cubic centimeters, preferably 40 cubic centimeters to 70 cubic centimeters, and more preferably 40 cubic centimeters to 60 cubic centimeters.

[0124] The draw-out resistance (RTD) of the permeable body portion may be at least 10 mmH2O. Preferably, the RTD of the permeable body portion is at least 20 mmH2O. More preferably, the RTD of the permeable body portion is at least 30 mmH2O. Even more preferably, the RTD of the permeable body portion is at least 40 mmH2O. In a particularly preferred embodiment, the RTD of the permeable body portion is at least 50 mmH2O.

[0125] The RTD of the breathable body portion may be up to 150 mmH2O. Preferably, the RTD of the breathable body portion is 120 mmH2O or less. More preferably, the RTD of the breathable body portion is 100 mmH2O or less. Even more preferably, the RTD of the breathable body portion is 80 mmH2O or less. In a particularly preferred embodiment, the RTD of the breathable body portion is 60 mmH2O or less.

[0126] For example, the RTD of the breathable main body is 10 to 150 mmH2O, preferably 20 to 150 mmH2O, more preferably 30 to 150 mmH2O, even more preferably 40 to 150 mmH2O, and particularly preferably 50 to 150 mmH2O.

[0127] For example, the RTD of the breathable main body is 10 to 120 mmH2O, preferably 20 to 120 mmH2O, more preferably 30 to 120 mmH2O, even more preferably 40 to 120 mmH2O, and particularly preferably 50 to 120 mmH2O.

[0128] For example, the RTD in the breathable main body portion is 10 to 100 mmH2O, preferably 20 to 100 mmH2O, more preferably 30 to 100 mmH2O, even more preferably 40 to 100 mmH2O, and particularly preferably 50 to 100 mmH2O.

[0129] For example, the RTD of the breathable main body portion is 10 to 80 mmH2O, preferably 20 to 80 mmH2O, more preferably 30 to 80 mmH2O, even more preferably 40 to 80 mmH2O, and particularly preferably 50 to 80 mmH2O.

[0130] In a system comprising an aerosol generator and an aerosol generating article, including a heater assembly having a heating body with a breathable body portion as described above, it will be understood that the overall RTD experienced by the user is generally the sum of the RTD of the breathable body portion, the RTD of the other components of the aerosol generator, and the RTD of the aerosol generating article. For example, other airflow path portions defined by the aerosol generator will contribute substantially to the overall RTD.

[0131] As briefly described above, in some embodiments, the heater assembly comprises a hollow tubular body portion that defines a chamber having an open end for receiving at least a portion of the aerosol-generating article.

[0132] In some preferred embodiments, the heater assembly is provided with a covering on the inner surface of the chamber. The covering may be a protective covering. The covering may be a thermally conductive covering. The covering may be positioned on the inner surface of the chamber such that when the aerosol-generating article is received into the chamber, the covering comes into contact with the aerosol-generating article but does not come into contact with the hollow tubular body made of polymer composite material. During use, the protective layer advantageously provides a separation between the hollow tubular body portion and the aerosol-generating article received into the chamber. In other words, the protective layer forms a "skin" that can prevent the accidental release of any conductive material (such as graphite) from the polymer composite into the chamber or into the aerosol-generating article. Furthermore, the covering can improve heat transfer from the heater assembly to the aerosol-generating article.

[0133] The hollow tubular body portion preferably contains at least 50 weight percent of polymer composite material. More preferably, the hollow tubular body portion contains at least 60 weight percent of polymer composite material. Even more preferably, the hollow tubular body portion contains at least 75 weight percent of polymer composite material.

[0134] In a preferred embodiment, the hollow tubular body portion comprises at least 80 weight percent of polymer composite material, preferably at least 90 weight percent of polymer composite material, and more preferably at least 95 weight percent of polymer composite material.

[0135] In some particularly preferred embodiments, the hollow tubular body portion is substantially entirely made of a polymer composite material.

[0136] When the hollow tubular body portion is primarily made from polymer composites, it is advantageous that it is easier to impart the desired shape to the body portion. In particular, substantially forming the hollow tubular body portion from polymer composites is advantageous from a manufacturing standpoint because it is generally easier to process the body portion as a whole, such as by molding or extrusion. This has the advantage that properties such as density and resistivity are substantially homogeneous throughout the hollow tubular body portion, and it is easier to control the wall thickness of the hollow tubular element.

[0137] In certain embodiments, the hollow tubular body portion is arranged such that the heating body is in direct contact with the aerosol generating article when the aerosol generating article is inserted into the chamber. This may be advantageous for heat transfer by conduction from the heating body to the aerosol generating substrate when the aerosol generating article is received in the chamber. At the same time, this may help to stably hold the aerosol generating article within the chamber.

[0138] In some embodiments, the hollow tubular body portion comprises a hollow tube element having an inner diameter of at least 4 millimeters. Preferably, the hollow tube element has an inner diameter of at least 5 millimeters. More preferably, the hollow tube element has an inner diameter of at least 6 millimeters.

[0139] In some embodiments, the hollow tube element has an inner diameter of 8 mm or less. Preferably, the hollow tube element has an inner diameter of 9 mm or less. More preferably, the hollow tube element has an inner diameter of 10 mm or less.

[0140] In some embodiments, the hollow tubular support element has an inner diameter of 4 mm to 10 mm, preferably 5 mm to 10 mm, and more preferably 6 mm to 10 mm.

[0141] In some embodiments, the hollow tubular support element has an inner diameter of 4 mm to 9 mm, preferably 5 mm to 9 mm, and more preferably 6 mm to 9 mm.

[0142] In some embodiments, the hollow tubular support element has an inner diameter of 4 mm to 8 mm, preferably 5 mm to 8 mm, and more preferably 6 mm to 8 mm.

[0143] The inner diameter of the hollow tube element can be selected and adjusted to accommodate an aerosol-generating article of a given shape and size.

[0144] The thickness of the hollow tube element may be at least 0.5 millimeters. Preferably, the thickness of the hollow tube element is at least 0.6 millimeters. More preferably, the thickness of the hollow tube element is at least 0.8 millimeters. Even more preferably, the thickness of the hollow tube element is at least 1 millimeter.

[0145] The thickness of the hollow tube element is preferably 5 millimeters or less. The thickness of the hollow tube element is more preferably 4 millimeters or less. The thickness of the hollow tube element is even more preferably 3 millimeters or less.

[0146] In some embodiments, the thickness of the hollow tube element is 0.5 mm to 5 mm, preferably 0.6 mm to 5 mm, more preferably 0.8 mm to 5 mm, and even more preferably 1 mm to 5 mm.

[0147] In some embodiments, the thickness of the hollow tube element is 0.5 mm to 4 mm, preferably 0.6 mm to 4 mm, more preferably 0.8 mm to 4 mm, and even more preferably 1 mm to 4 mm.

[0148] In some embodiments, the thickness of the hollow tube element is 0.5 mm to 3 mm, preferably 0.6 mm to 3 mm, more preferably 0.8 mm to 3 mm, and even more preferably 1 mm to 3 mm.

[0149] While we do not wish to be bound by theory, if a potential difference is applied between the ends of a hollow tube element, the electrical resistance of the hollow tube element is approximately inversely proportional to the area of ​​the cross-section of the hollow tube element. Therefore, the thickness of the hollow tube element may be selected to impart sufficient structural strength to the heater assembly and to adjust the overall resistance of the heating body, which in turn affects the overall heat output generated during use.

[0150] In the heater assembly according to the embodiment of the present invention, the overall resistance of the heating body is preferably 0.75 ohms to 1.25 ohms, more preferably 0.8 ohms to 1.2 ohms, and even more preferably 0.9 ohms to 1.1 ohms.

[0151] While we do not wish to be bound by theory, an exemplary heating body having resistance within the aforementioned range can, advantageously, be paired with a commercially available battery, such as a lithium battery, to generate power in the range of 8 to 10 watts. Such power is suitable for efficiently and reliably heating the aerosol generating substrate of an aerosol generating article to a temperature in the range of approximately 200 to 250 degrees Celsius.

[0152] As briefly described above, the heating body of the heater assembly according to the present invention includes a polymer matrix and a polymer composite material comprising graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

[0153] The polymer matrix preferably contains at least one of polyether ether ketone (PEEK) and liquid crystal polymer (LCP).

[0154] The polymer matrix may constitute at least 10 weight percent of the heating body. Preferably, the polymer matrix constitutes at least 15 weight percent of the heating body. More preferably, the polymer matrix constitutes at least 20 weight percent of the heating body. Even more preferably, the polymer matrix constitutes at least 22 weight percent of the heating body.

[0155] The polymer matrix may occupy up to 55% by weight of the heating body. Preferably, the polymer matrix occupies 45% by weight or less of the heating body. More preferably, the polymer matrix occupies 35% by weight or less of the heating body. Even more preferably, the polymer matrix occupies 33% by weight or less of the heating body.

[0156] In some embodiments, the polymer matrix accounts for 10 to 55 weight percent of the heating body, preferably 15 to 55 weight percent, more preferably 20 to 55 weight percent, and even more preferably 22 to 55 weight percent.

[0157] In other embodiments, the polymer matrix accounts for 10 to 45 weight percent of the heating body, preferably 15 to 45 weight percent, more preferably 20 to 45 weight percent, and even more preferably 22 to 45 weight percent of the heating body.

[0158] In further embodiments, the polymer matrix accounts for 10 to 35 weight percent of the heating body, preferably 15 to 35 weight percent, more preferably 20 to 35 weight percent, and even more preferably 22 to 35 weight percent of the heating body.

[0159] In yet another embodiment, the polymer matrix accounts for 10 to 33 weight percent of the heating body, preferably 15 to 33 weight percent, more preferably 20 to 33 weight percent, and even more preferably 22 to 33 weight percent of the heating body.

[0160] When the polymer matrix constitutes the proportions described above, it is advantageous to benefit from a satisfactory level of malleability and overall processability of the polymer composite, which can facilitate the entire manufacturing process.

[0161] The graphite-derived material preferably contains at least one of expanded graphite and graphite nanoplatelets.

[0162] In the heater assembly according to the present invention, at least one of graphite, graphite-derived material, and hexagonal boron nitride may constitute at least 30 weight percent of the heating body. Preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 45 weight percent of the heating body. More preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 60 weight percent of the heating body. Even more preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 62 weight percent of the heating body.

[0163] At least one of graphite, graphite-derived material, and hexagonal boron nitride may constitute up to 80 weight percent of the heating body. Preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 75 weight percent or less of the heating body. More preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 70 weight percent or less of the heating body. Even more preferably, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 69 weight percent or less of the heating body.

[0164] In some embodiments, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 30 to 80 weight percent of the heating body, preferably 45 to 80 weight percent, more preferably 60 to 80 weight percent, and even more preferably 62 to 80 weight percent.

[0165] In some embodiments, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 30 to 75 percent by weight of the heating body, preferably 45 to 75 percent by weight, more preferably 60 to 75 percent by weight, and even more preferably 62 to 75 percent by weight.

[0166] In some embodiments, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 30 to 70 percent by weight of the heating body, preferably 45 to 70 percent by weight, more preferably 60 to 70 percent by weight, and even more preferably 62 to 70 percent by weight.

[0167] In some embodiments, at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes 30 to 69 weight percent of the heating body, preferably 45 to 69 weight percent, more preferably 60 to 69 weight percent, and even more preferably 62 to 69 weight percent.

[0168] The inventors observed that the conductivity of the polymer composite material in the heating body of the heater assembly according to the present invention can be controlled to some extent by the degree of dispersion and aggregation of at least one particle among graphite, graphite-derived material, and hexagonal boron nitride in the polymer matrix.

[0169] High dispersion of at least one conductive particle among graphite, graphite-derived material, and hexagonal boron nitride within the polymer matrix is ​​generally to be avoided, as it is understood to lead to very low or no conductivity in the polymer composite. High aggregation without dispersion of conductive particles should also be avoided, as this typically leads to a severe anisotropic distribution of properties throughout the heating body.

[0170] The inventors observed that as long as the concentration of at least one of graphite, graphite-derived material, and hexagonal boron nitride in the polymer matrix remains below a certain value, the particles remain substantially isolated, and thus the entire polymer composite can substantially behave as a dielectric medium. On the other hand, when a certain critical volume of conductive particles ("perfusion threshold") is combined with a polymer matrix that is otherwise essentially insulated, the electrical conductivity of the resulting polymer composite increases by an order of magnitude. While we do not wish to be bound by theory, this is understood to occur because, at concentrations of graphite, graphite-derived material, and at least one of hexagonal boron nitride particles approaching the perfusion threshold, the particles tend to form a quasi-continuous network within the polymer matrix.

[0171] Further increasing the concentration of conductive particles generally induces a smaller increase in the overall conductivity of the polymer composite, which approaches a plateau.

[0172] It has been found that including at least one polymer matrix of graphite, graphite-derived material, and hexagonal boron nitride within the polymer matrix within the above-mentioned range generally encompasses or approximates the perfusion threshold. As a result, it has been found that including at least one of graphite, graphite-derived material, and hexagonal boron nitride within the polymer matrix within the above-mentioned range leads to a generally satisfactory level of conductivity of the heating body.

[0173] These were then found to be related to the ability of a heating body to generate sufficient thermal output to heat the aerosol generating substrate to a temperature sufficient to release and deliver a desired amount of aerosol species to the consumer, directly or indirectly, or both, by a preheated flow of air. For example, heater assemblies comprising a heating body having the above-described composition have been used to successfully and consistently heat tobacco-containing aerosol generating substrates to temperatures in the range of 200-250 degrees Celsius.

[0174] The heating body may contain one or more additives. In some embodiments, the heating body contains at least one additive dispersed within a polymer matrix.

[0175] At least one additive may contain carbon black.

[0176] At least one additive may include a wax. The term “wax” is used here to refer to an organic compound that is a lipophilic, malleable solid near room temperature. Waxes typically contain higher alkanes and lipids, with melting points above approximately 40 degrees Celsius. Upon melting, waxes yield a low-viscosity liquid. Waxes are insoluble in water but soluble in non-polar organic solvents such as hexane, benzene, and chloroform. Suitable waxes include natural waxes such as animal and plant waxes, as well as synthetic waxes derived from petroleum.

[0177] At least one additive may include a dispersant. The term “dispersant” is used here to mean a compound or composition that, when added to a suspension of solid or liquid particles in a liquid (e.g., a colloid or emulsion), is adapted to improve the separation of particles and prevent them from accumulating in precipitates or aggregates. Dispersants are typically applied to paints to facilitate the dispersion of solid pigments.

[0178] In the context of the present invention, the addition of a dispersant can facilitate the dispersion of conductive particles of graphite, graphite-derived materials, and hexagonal boron nitride within the polymer matrix. Furthermore, the dispersant advantageously prevents the tendency of conductive particles to aggregate, which can be detrimental in terms of the overall electrical conductivity of the heating body. At least one additive may constitute at least 1 weight percent of the heating body. Preferably, at least one additive constitutes at least 2 weight percent of the heating body. More preferably, at least one additive constitutes at least 4 weight percent of the heating body. Even more preferably, at least one additive constitutes at least 5 weight percent of the heating body.

[0179] At least one additive may constitute up to 15 weight percent of the heating body. Preferably, at least one additive constitutes 12 weight percent or less of the heating body. More preferably, at least one additive constitutes 10 weight percent or less of the heating body. Even more preferably, at least one additive constitutes 9 weight percent or less of the heating body.

[0180] In some embodiments, at least one additive is 1% to 15% by weight of heating body, preferably 2% to 15% by weight of heating body, more preferably 4% to 15% by weight of heating body, and even more preferably 5% to 15% by weight of heating body.

[0181] In some embodiments, at least one additive comprises 1% to 12% by weight of heating body, preferably 2% to 12% by weight of heating body, more preferably 4% to 12% by weight of heating body, and even more preferably 5% to 12% by weight of heating body.

[0182] In some embodiments, at least one additive is 1% to 10% by weight of heating body, preferably 2% to 10% by weight of heating body, more preferably 4% to 10% by weight of heating body, and even more preferably 5% to 10% by weight of heating body.

[0183] In some embodiments, at least one additive comprises 1% to 9% by weight of heating body, preferably 2% to 9% by weight of heating body, more preferably 4% to 9% by weight of heating body, and even more preferably 5% to 9% by weight of heating body.

[0184] As briefly described above, the heating body is configured for resistance heating. In some embodiments, the heater assembly comprises two or more electrodes operably connected to the heating body.

[0185] Two or more electrodes may be connected to the heating body in multiple ways. For example, the heater assembly may comprise two ring-shaped electrodes attached to opposing ends (i.e., the upstream and downstream ends, respectively) of the hollow tubular body portion of the heating body. Alternatively, the heater assembly may comprise two elongated electrodes attached to the outer surface of the hollow tubular body portion, extending along the longitudinal axis of the heating body and preferably at opposite, opposing positions. Both arrangements are suitable for passing an electric current through the heating body and thus generating heat by the Joule effect.

[0186] In some embodiments, two or more electrodes may be partially or completely embedded within the heating body. This can be advantageously achieved by overmolding a polymer composite forming the heating body onto two or more conductive elements, such as two or more metal elements, which function as electrical connecting electrodes. This is beneficial both from a manufacturing standpoint and in ensuring a better and more durable electrical connection between the electrodes and the polymer composite forming the heating body.

[0187] The heater assembly described above is used, in particular, in an aerosol generating device for heating the aerosol generating substrate of an aerosol generating article.

[0188] The aerosol generator comprises a heater assembly consistent with the above description, and a power supply and control device connected to a heating body, configured to apply a voltage to the heating body during use so that heat is generated by resistive heating due to the passage of current through the heating body.

[0189] In some embodiments, the aerosol generator includes an inductor coil extending around at least a portion of a heating body. A power supply and control device are connected to the inductor coil and configured to supply a fluctuating current to the inductor coil so that, when in use, the inductor coil generates a fluctuating magnetic field.

[0190] The inductor coil can be positioned in direct contact with the outer surface of the heating body.

[0191] The control device may be configured to supply electrical energy from a power source to an inductor coil as alternating current, thereby enabling the inductor coil to generate heat by one or a combination of i) resistive heating of the inductor coil and ii) heating of the heating body through inductive coupling of the inductor coil with the heating body. The control device may be configured to adjust at least one parameter of the alternating current to change the inductive coupling of the inductor coil with the heating body, thereby adjusting the balance between the heat generated through resistive heating of the inductor coil and the heat generated by the inductive coupling of the inductor coil with the heating body.

[0192] As used herein, the term "inductively coupled" refers to the heating of a susceptor element, such as the heating body of a heater assembly, when penetrated by an alternating magnetic field. Heating may be caused by the generation of eddy currents within the heating body. Heating may also be caused by magnetic hysteresis losses.

[0193] In a preferred embodiment, at least one of the control device and the heating body is configured to prevent inductive coupling between the heating body and the inductor coil during use.

[0194] For example, this can be achieved by configuring the control device to adjust the frequency of the alternating current. The inductive coupling between the inductor coil and the heating body changes with the change in the frequency of the alternating current. The frequency is a value f associated with the alternating current that generates an alternating magnetic field that provides optimal coupling with the heating body in order to enable almost the entire transfer of energy from the inductor coil to the heating body. susceptor It can be adjusted to have such that, as a result, most of the heat is generated by the induction heating of the heating body. The frequency is also a value f associated with the alternating current that generates an alternating magnetic field that provides little or no coupling with the heating body, allowing almost all of the energy to remain in the inductor coil. inductor coil It can be adjusted to have such that, as a result, most of the heat is generated by the resistive heating of the inductor coil. The frequency is also a value f associated with the alternating current that results in a combination of inductive heating of the heating body and resistive heating of the inductor coil. total These frequencies can be adjusted to have the following characteristics. Each of these frequencies varies depending on the materials, physical properties, and configuration of the inductor coil and heating body, such as the inductance of the inductor coil and the permeability of the polymer composite material on which the heating body is formed.

[0195] Another way to achieve inductive isolation of the inductor coil and the heating body is to configure the heating body such that it is substantially permeable to the alternating magnetic field generated by the inductor coil when an alternating current is supplied to the inductor coil.

[0196] The inventors have found that a heating body containing at least 50 weight percent of the polymer composite material described herein can be essentially sufficiently permeable to the alternating magnetic field generated by the inductor coil when an alternating current is supplied to the inductor coil. While we do not wish to be bound by theory, it is understood that the polymer composite material is anisotropic in terms of resistivity in polymer composite materials. More specifically, it has been observed that the tangential resistivity is more than twice (and even more than 2.5 times) the axial resistivity. As a result, only a small current flow occurs within the hollow tubular body portion of the heating body, which significantly limits power loss.

[0197] Furthermore, the inventors discovered that the hollow tubular heating body can be completely transparent to the alternating magnetic field generated by the inductor coil when an alternating current is supplied to the inductor coil, by providing multiple slits along the long axis in the wall of the hollow tubular element.

[0198] In certain embodiments, the control device is configured to provide a fluctuating current in the form of an alternative current having a frequency selected to prevent inductive coupling between the heating body and the inductor coil during use.

[0199] The aerosol generator preferably further comprises a housing, and the inductor coil (if present), heater assembly, power supply, and control device are positioned within the housing.

[0200] The housing may be elongated. The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0201] The control device may be configured to enter standby mode at the start of a usage session, detect the start of user inhalation, switch from standby mode to operating mode in response to the detection of the start of user inhalation, detect the end of user inhalation, and switch from operating mode to standby mode in response to the detection of the end of user inhalation.

[0202] The power source may be in the form of a battery. The battery may be rechargeable. The battery may be a lithium-based battery, such as a lithium cobalt battery, lithium iron phosphate battery, lithium titanate battery, or lithium polymer battery. The battery may be a nickel-metal hydride battery or a nickel-cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and may be configured for numerous charge and discharge cycles. The power source may have a capacity that allows for the storage of sufficient energy for one or more user experiences of the aerosol generating system. For example, the power source may have a capacity that allows for continuous aerosol generation for about six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke one conventional cigarette. In another embodiment, the power source may have a capacity that allows for a predetermined number of puffs or discontinuous operation of the aerosol generating system.

[0203] The control device or control circuit may be, or include, any suitable control device or electrical component. The control device may include memory. Information for carrying out the methods described above may be stored in memory. The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application-specific integrated circuit (ASIC) or other electronic circuit capable of providing control. The control circuit may be configured to supply power to the heating element continuously after the device has been operated, or to supply power intermittently, such as per smoke extraction. Power may be supplied to the heating element in the form of current pulses, for example by pulse width modulation (PWM). The control circuit may include further electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element. The control device may be configured to increase the power supplied to one or more heaters during operation mode compared to standby mode.

[0204] In an aerosol generator equipped with a heater assembly as described above, the permeable body portion of the heating unit may be configured as the first heater.

[0205] In some embodiments of an aerosol generator equipped with a heater assembly as described above, the permeable body portion of the heating body is configured as a first heater, and the hollow tubular body portion of the heating body is configured as a second heater.

[0206] In another embodiment of the aerosol generator equipped with a heater assembly as described above, the permeable body portion of the heating body is configured as a first heater, and a further heat source (e.g., an inductor coil) is configured as a second heater.

[0207] The first heater may be configured to heat the aerosol generating substrate during standby mode, while the second heater may be configured not to heat the aerosol generating substrate during standby mode.

[0208] Both the first and second heaters may be arranged to simultaneously heat the aerosol-forming substrate during the operating mode.

[0209] The first heater may be configured to operate throughout the entire usage session, while the second heater may be configured to operate only while the user is smoking. For example, the second heater may be switched on only while the user is smoking. Alternatively, the second heater may operate throughout the entire usage session, but the power supplied to the second heater may be increased while the user is smoking.

[0210] The aerosol generating device described above may form an aerosol generating system having an aerosol generating article for use in the aerosol generating device, i.e., an aerosol forming substrate, and the aerosol generating device is configured to receive at least a portion of the aerosol generating article. Preferably, the aerosol generating article is configured such that at least a portion of the aerosol forming substrate is thermally bonded to the heating body when the aerosol generating article is inserted into the aerosol generating device.

[0211] In some embodiments, the aerosol-generating article further comprises a susceptor element. For example, the susceptor element may be provided within the aerosol-generating substrate, such as being embedded within the aerosol-generating substrate. [Examples]

[0212] A non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, or forms, or aspects described herein.

[0213] Example 1: A heater assembly for an aerosol generator, comprising a heating body configured for resistance heating, wherein the heating body comprises a polymer composite material including a polymer matrix and at least one conductive particulate material dispersed within the polymer matrix. Example 2: The heater assembly according to Example 1, wherein at least one conductive particulate material is at least one of graphite, a graphite-derived material, and hexagonal boron nitride. Example 3: The heating body is a heater assembly according to Example 1 or Example 2, comprising a breathable body portion that defines an airflow path through a breathable body portion. Example 4: The heater assembly according to Example 3, wherein the heating body comprises a hollow tubular body portion defining a chamber having an open end for receiving at least a portion of an aerosol-generating article, and an airflow path is located upstream of the chamber and is in fluid communication with it. Example 5: The heater assembly described in Example 4, wherein the equivalent free cross-sectional area of ​​the airflow path is smaller than the free cross-sectional area of ​​the chamber. Example 6: The heater assembly according to Example 4 or Example 5, wherein the breathable main body portion is at least partially disposed within the hollow tubular main body portion of the heating body. Example 7: The heater assembly described in Example 6, wherein the breathable main body is substantially integrated with the hollow tubular main body of the heating unit. Example 8: The breathable main body is a porous body, as described in any one of Examples 3 to 7 of the heater assembly. Example 8: The heater assembly according to any one of Examples 4 to 7, wherein the breathable body portion comprises at least 50 weight percent of polymer composite material, or at least 60 weight percent of polymer composite material, or at least 75 weight percent of polymer composite material, or at least 90 weight percent of polymer composite material, or at least 95 weight percent of polymer composite material, or the breathable body portion is entirely made of polymer composite material. Example 9: The breathable main body is a porous body formed by sintering polymer composite particles, as described in any one of Examples 4 to 8. Example 10: The heater assembly according to any one of Examples 4 to 9, wherein the cross-sectional void ratio of the breathable main body is at least 15 percent. Example 11: The heater assembly according to any one of Examples 4 to 9, wherein the cross-sectional void ratio of the breathable main body is at least 20 percent. Example 12: The heater assembly according to any one of Examples 4 to 9, wherein the cross-sectional void ratio of the breathable main body is at least 25 percent. Example 13: A heater assembly according to any one of Examples 4 to 12, wherein the cross-sectional void ratio of the breathable main body is 45 percent or less. Example 14: The heater assembly described in any one of Examples 4 to 12, wherein the cross-sectional void ratio of the breathable main body is 40 percent or less. Example 15: The heater assembly described in any one of Examples 4 to 12, wherein the cross-sectional void ratio of the breathable main body is 35 percent or less. Example 16: The heater assembly according to any one of Examples 4 to 15, wherein the draw-to-discharge (RTD) of the breathable body portion is at least 10 mmH2O. Example 17: The heater assembly described in any one of Examples 4 to 15 has a draw-to-discharge (RTD) of at least 20 milliH2O. Example 18: The heater assembly described in any one of Examples 4 to 15 has a draw-to-discharge (RTD) of at least 30 milliH2O. Example 19: The heater assembly described in any one of Examples 4 to 15 has a draw-to-discharge (RTD) of at least 40 mmH2O. Example 20: The heater assembly described in any one of Examples 4 to 15 has a draw-to-discharge (RTD) of at least 50 milliH2O. Example 21: The heater assembly described in any one of Examples 4 to 20 has a draw-to-discharge (RTD) of 150 mmH2O or less for the breathable main body. Example 22: The heater assembly described in any one of Examples 4 to 20 has a draw-to-discharge (RTD) of 120 mmH2O or less for the breathable main body. Example 23: The heater assembly described in any one of Examples 4 to 20 has a draw-to-discharge (RTD) of 100 mmH2O or less for the breathable main body. Example 24: The heater assembly described in any one of Examples 4 to 20 has a draw-to-discharge (RTD) of 80 mmH2O or less. Example 25: The heater assembly according to any one of Examples 1 to 3, wherein the heating body comprises a hollow tubular body portion defining a chamber having an open end for receiving at least a portion of an aerosol-generating article. Example 26: A heater assembly according to any one of Examples 4 to 25, wherein the hollow tubular body portion comprises at least 50 weight percent of polymer composite material, or at least 60 weight percent of polymer composite material, or at least 75 weight percent of polymer composite material, or at least 90 weight percent of polymer composite material, or at least 95 weight percent of polymer composite material, or the hollow tubular body portion is entirely made of polymer composite material. Example 27: The heater assembly according to any one of Examples 4 to 26, wherein the hollow tubular body portion is arranged so that the heating body comes into direct contact with the aerosol generating article when the aerosol generating article is inserted into the chamber. Example 28: The heater assembly according to any one of Examples 4 to 27, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of at least 4 millimeters. Example 29: The heater assembly according to any one of Examples 4 to 27, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of at least 5 millimeters. Example 30: The heater assembly according to any one of Examples 4 to 27, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of at least 6 millimeters. Example 31: The heater assembly according to any one of Examples 4 to 30, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of 10 millimeters or less. Example 32: The heater assembly according to any one of Examples 4 to 30, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of 9 mm or less. Example 33: The heater assembly according to any one of Examples 4 to 30, wherein the hollow tubular body portion comprises a hollow tubular element having an inner diameter of 8 mm or less. Example 34: A heater assembly according to any one of Examples 4 to 33, wherein the thickness of the hollow tube element is at least 0.5 millimeters. Example 35: The heater assembly according to any one of Examples 4 to 33, wherein the thickness of the hollow tube element is at least 1 millimeter. Example 36: A heater assembly according to any one of Examples 4 to 33, wherein the thickness of the hollow tube element is at least 1.5 millimeters. Example 37: A heater assembly according to any one of Examples 4 to 36, wherein the thickness of the hollow tube element is 5 millimeters or less. Example 38: A heater assembly according to any one of Examples 4 to 36, wherein the thickness of the hollow tube element is 3 millimeters or less. Example 39: The heater assembly according to any one of Examples 1 to 38, wherein the polymer matrix comprises at least one of polyether ether ketone (PEEK) and liquid crystal polymer (LCP). Example 40: A heater assembly according to any one of Examples 1 to 39, wherein the polymer matrix constitutes at least 10 weight percent of the heating body. Example 41: A heater assembly according to any one of Examples 1 to 39, wherein the polymer matrix constitutes at least 15 weight percent of the heating body. Example 42: A heater assembly according to any one of Examples 1 to 39, wherein the polymer matrix constitutes at least 20 weight percent of the heating body. Example 43: The polymer matrix constitutes 55% by weight or less of the heating body, and is part of the heater assembly described in any one of Examples 1 to 42. Example 44: The polymer matrix constitutes 45% by weight or less of the heating body, and is part of the heater assembly described in any one of Examples 1 to 42. Example 45: The polymer matrix constitutes 35% by weight or less of the heating body, and is part of the heater assembly described in any one of Examples 1 to 42. Example 46: The graphite-derived material is a heater assembly according to any one of Examples 2 to 45, comprising at least one of expanded graphite and graphite nanoplatelets. Example 47: A heater assembly according to any one of Examples 2 to 46, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 30 weight percent of the heating body. Example 48: A heater assembly according to any one of Examples 2 to 46, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 45 weight percent of the heating body. Example 49: A heater assembly according to any one of Examples 2 to 46, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride constitutes at least 60 weight percent of the heating body. Example 50: A heater assembly according to any one of Examples 2 to 49, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride accounts for 80 percent or less by weight of the heating body. Example 51: A heater assembly according to any one of Examples 2 to 49, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride accounts for 75 percent or less by weight of the heating body. Example 50: A heater assembly according to any one of Examples 2 to 49, wherein at least one of graphite, graphite-derived material, and hexagonal boron nitride accounts for 70 percent or less by weight of the heating body. Example 51: The heating body is a heater assembly according to any one of Examples 1 to 50, further comprising at least one additive dispersed in a polymer matrix. Example 52: The heater assembly according to Example 51, wherein at least one additive contains carbon black. Example 53: The heater assembly according to Example 51 or Example 52, wherein at least one additive comprises a dispersant. Example 54: A heater assembly according to any one of Examples 51 to 53, wherein at least one additive constitutes at least 1 weight percent of the heating body. Example 55: A heater assembly according to any one of Examples 51 to 53, wherein at least one additive constitutes at least 2 weight percent of the heating body. Example 56: A heater assembly according to any one of Examples 51 to 53, wherein at least one additive constitutes at least 4 weight percent of the heating body. Example 57: A heater assembly according to any one of Examples 51 to 53, wherein at least one additive constitutes at least 5 weight percent of the heating body. Example 58: A heater assembly according to any one of Examples 51 to 57, wherein at least one additive accounts for 15 percent or less by weight of the heating body. Example 59: A heater assembly according to any one of Examples 51 to 57, wherein at least one additive accounts for 12 percent or less by weight of the heating body. Example 60: A heater assembly according to any one of Examples 51 to 57, wherein at least one additive accounts for 10% or less by weight of the heating body. Example 61: A heater assembly according to any one of Examples 1 to 60, further comprising at least two electrodes operably connected to a heating body. Example 62: An aerosol generator comprising a heater assembly described in any one of Examples 1 to 61, and a power supply and control device connected to a heating body, configured to apply a voltage to the heating body during use so that heat is generated by resistive heating due to the passage of current within the heating body. Example 63: The aerosol generator according to Embodiment 62, further comprising an inductor coil extending around at least a portion of the heating body, wherein a power supply and control device are connected to the inductor coil and configured to supply a fluctuating current to the inductor coil so that the inductor coil generates a fluctuating magnetic field when in use. Example 64: The aerosol generator according to Example 63, wherein the inductor coil is positioned in direct contact with the outer surface of the heating body. Example 65: The aerosol generator according to any one of Examples 62 to 64, wherein at least one of the control device and the heating body is configured to prevent inductive coupling between the heating body and the inductor coil during use. Example 66: The aerosol generator according to Example 65, wherein the control device is configured to provide a fluctuating current in the form of an alternative current having a frequency selected to prevent inductive coupling between the heating body and the inductor coil during use. Example 67: The aerosol generator according to any one of Examples 62 to 66, further comprising a housing, wherein the inductor coil, heating body, power supply, and control device are positioned within the housing. Example 68: An aerosol generating system comprising an aerosol generating device according to any one of Examples 62 to 67 and an aerosol generating article comprising an aerosol forming substrate, wherein the aerosol generating device is configured to receive at least a portion of the aerosol generating article. Example 69: The aerosol generating system according to Example 68, wherein the aerosol generating article is configured such that, when the aerosol generating article is inserted into the aerosol generating device, at least a portion of the aerosol forming substrate is thermally bonded to the heating body. Example 70: The aerosol generating article is the aerosol generating system according to Example 68 or Example 69, further comprising a susceptor element.

[0214] The present invention will be further described, for illustrative purposes only, with reference to the attached drawings. [Brief explanation of the drawing]

[0215] [Figure 1] Figure 1 shows a side cross-sectional view of an aerosol generator equipped with a heater assembly according to the present invention. [Figure 2] Figure 2 shows a side cross-sectional view of an aerosol generation system equipped with the aerosol generator shown in Figure 1. [Modes for carrying out the invention]

[0216] Figures 1 and 2 show an aerosol generator 210 including a heater assembly 212 according to the present invention.

[0217] The heater assembly 212 comprises a heating body including a hollow portion 214 that partially defines a chamber 216 for receiving a portion of an aerosol-generating article. The chamber 216 comprises an open end 218 through which the aerosol-generating article can be inserted into the chamber 216, and a closed end 220 opposite the open end 218. More specifically, the hollow portion 214 comprises a tubular element 228 that partially defines a cylindrical wall 222 of the chamber 216 extending between the open end 218 and the closed end 220.

[0218] The tubular element 228 is positioned such that when the aerosol generating article is inserted into the chamber 216, the aerosol generating article is received within the tubular element 228 and comes into direct contact with the tubular element 228. Advantageously, the direct contact between the tubular element 228 and the aerosol generating article facilitates the transfer of heat generated within the tubular element 228 to the aerosol generating article by the Joule effect when a voltage is applied to the hollow body portion 214.

[0219] The heating body of the heater assembly 212 further comprises a permeable body portion in the form of a porous portion 230 that defines an airflow path through the porous portion 230. The airflow path is upstream of the chamber 216 and is in fluid communication with it. The equivalent free cross-sectional area of ​​the airflow path is smaller than the free cross-sectional area of ​​the chamber 216. In the embodiments shown in Figures 1 and 2, the porous portion 230 comprises a porous plug 234 provided within a tubular element 228.

[0220] The porous portion has a cross-sectional porosity of 30 percent. The length of the porous portion, measured along the long axis of the heater assembly, is 2 to 5 millimeters. The RTD of the porous portion is 50 mmH2O to 60 mmH2O.

[0221] An inductor coil 224, comprising multiple windings 226, extends around the outer surface of a tubular element 228. The inductor coil 224 is positioned such that the multiple windings are in direct contact with the outer surface of the tubular element 228. Advantageously, positioning the inductor coil 224 in direct contact with the outer surface of the tubular element 228 facilitates the transfer of heat generated by the resistive heating of the inductor coil 224 to the tubular element 228. The inductor coil 24 and the thermal conductive element 228 are arranged concentrically around the central axis 236 of the aerosol generator 210.

[0222] The aerosol generator 210 also includes a control device 240 and a power supply 242 connected to an inductor coil 224. The control device 240 is configured to supply an alternating current from the power supply 242 to the inductor coil 224 in order to generate an alternating magnetic field.

[0223] Figure 2 shows a cross-sectional view of an aerosol generating system 300 comprising the aerosol generating device 210 and aerosol generating article 302 shown in Figure 1.

[0224] The aerosol generating article 302 comprises an aerosol-forming substrate 304 in the form of a cigarette plug, a first hollow acetate tube 306, a second hollow acetate tube 308, a mouthpiece 310, and an outer wrapper 312. The aerosol generating article 302 also comprises a susceptor element 314 disposed within the aerosol-forming substrate 304.

[0225] During use, a portion of the aerosol-generating article 302 is inserted into the chamber 216 such that the aerosol-forming substrate 304 and the susceptor element 314 are positioned inside the heating body and inductor coil 224 of the heater assembly 212. The control device 240 supplies alternating current from the power supply 42 to the inductor coil 224, generating an alternating magnetic field that inductively heats the susceptor element 314, which in turn heats the aerosol-forming substrate 304 and generates an aerosol. Furthermore, the heat generated in the inductor coil 224 itself due to the resistance loss of the inductor coil 224 is conducted from the inductor coil 224 to the aerosol-forming substrate 304 by the thermal conductive element 228.

[0226] The airflow through the aerosol generating system 300 in use is shown by the dashed line 316 in Figure 2. When a user inhales through the mouthpiece 310 of the aerosol generating article 302, negative pressure is generated in the chamber 216. The negative pressure draws air into the aerosol generating device 210 through the porous section 230 of the heater assembly 212, and the airflow is preheated by the heat resistively generated within the porous section 230. The airflow is then held over the aerosol forming substrate 304, which is received in the chamber 216 of the hollow section 214, and flows through it.

[0227] As the airflow passes through the aerosol-forming substrate 304, the aerosol generated by the heating of the aerosol-forming substrate 304 is carried along by the airflow. The aerosol then flows along the length of the aerosol-generating article 302, through the mouthpiece 310, and to the user.

[0228] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, percentages, etc., are understood to be modified in all cases by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum values, as well as any intermediate ranges contained within them, whether or not they are specifically enumerated herein. Thus, in this context, number A is understood as A ± 10 percent (10%) of A. In this context, number A may be considered to include a number that falls within the general standard error of the measured value of the property that number A modifies. In some cases used in the appended claims, number A may deviate by the percentages enumerated above, provided that the amount A deviates does not substantially affect the fundamental and novel property of the claimed invention. Furthermore, all ranges include the disclosed maximum and minimum values, as well as any intermediate ranges contained within them, whether or not they are specifically enumerated herein.

Claims

1. A heater assembly for an aerosol generator, comprising a heating body configured for resistance heating, wherein the heating body includes a polymer composite material comprising a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix.

2. The heater assembly according to claim 1, wherein the heating body comprises a breathable body portion that defines an airflow path through the porous portion.

3. The heater assembly according to claim 2, wherein the heating body comprises a hollow tubular body portion defining a chamber having an open end for receiving at least a portion of an aerosol-generating article, and the airflow path is located upstream of the chamber and is in fluid communication with it.

4. The heater assembly according to claim 3, wherein the breathable body portion is at least partially disposed within the hollow tubular body portion of the heating body.

5. The heater assembly according to claim 4, wherein the breathable body portion is substantially integrated with the hollow tubular body portion of the heating body.

6. The heater assembly according to any one of claims 3 to 5, wherein the breathable main body portion comprises at least 50 percent by weight of the polymer composite material.

7. The heater assembly according to any one of claims 3 to 6, wherein the breathable main body portion is formed by sintering the particles of the polymer composite material.

8. The heater assembly according to any one of claims 3 to 7, wherein the cross-sectional void ratio of the breathable main body portion is at least 15 percent.

9. The draw-out resistance (RTD) of the aforementioned breathable body portion is 100 mmH 2 A heater assembly according to any one of claims 3 to 8, wherein the value is 0 or less.

10. The heater assembly according to claim 1, wherein the heating body comprises a hollow tubular body portion that defines a chamber having an open end for receiving at least a portion of an aerosol-generating article.

11. The heater assembly according to any one of claims 1 to 10, wherein the polymer matrix comprises at least one of polyetheretherketone (PEEK) and liquid crystal polymer (LCP).

12. Aerosol generator, A heater assembly according to any one of claims 1 to 11, Aerosol generator comprising: a power supply and control device connected to the heating body, configured to apply a voltage to the heating body during use so that heat is generated by resistive heating due to the passage of electric current through the heating body.

13. Aerosol generation system, The aerosol generator according to claim 12, An aerosol generating system comprising an aerosol generating article having an aerosol-forming substrate, wherein the aerosol generating device is configured to receive at least a portion of the aerosol generating article.

14. The aerosol generating system according to claim 13, wherein the aerosol generating article is configured such that, when the aerosol generating article is inserted into the aerosol generating device, at least a portion of the aerosol forming substrate is thermally bonded with the heating body.

15. The aerosol generating system according to claim 13 or 14, wherein the aerosol generating article further comprises a susceptor element.

Images