EP4312620A1

EP4312620A1 - Aerosol generation device with comb-shaped electrodes

Info

Publication number: EP4312620A1
Application number: EP22719578.1A
Authority: EP
Inventors: Samuel John PAUL; Alec WRIGHT
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2021-03-30
Filing date: 2022-03-30
Publication date: 2024-02-07
Also published as: JP2024511931A; WO2022207743A1

Abstract

An aerosol generation device configured to generate an aerosol from a consumable comprising an aerosol substrate and a heating element comprising an electrically conductive material. The aerosol generation device comprises: a housing comprising a chamber adapted to hold the consumable; and an electrical supply surface comprising first and second comb-shaped electrodes, arranged in the chamber, wherein, when the heating element is located against the electrical supply surface, the first and second comb-shaped electrodes are configured to supply electricity through the electrically conductive material in order to heat the aerosol substrate.

Description

AEROSOL GENERATION DEVICE WITH COMB-SHAPED ELECTRODES

TECHNICAL FIELD

The present disclosure relates to aerosol generation devices and consumables for aerosol generation devices. The consumable may comprise tobacco or other suitable aerosol substrate materials to be heated, rather than burned, to generate an aerosol for inhalation.

BACKGROUND

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. Various devices and systems are available that heat or warm aerosolisable substances as opposed to burning tobacco in conventional tobacco products.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generation device or heat-not-burn device. Devices of this type generate an aerosol or vapour by heating an aerosol substrate that typically comprises moist leaf tobacco or other suitable aerosolisable material to a temperature typically in the range 150°C to 350°C. Heating an aerosol substrate, but not combusting or burning it, releases an aerosol that comprises the components sought by the user but not the toxic and carcinogenic by-products of combustion and burning. Furthermore, the aerosol produced by heating the tobacco or other aerosolisable material does not typically comprise the burnt or bitter taste resulting from combustion and burning that can be unpleasant for the user and so the substrate does not therefore require the sugars and other additives that are typically added to such materials to make the smoke and/or vapour more palatable for the user.

It is desirable to provide a consumable or aerosol generation device that can generate an aerosol with improved energy efficiency or with a reduced heat-up time. Additionally, in common examples of consumables and aerosol generation devices, a heating element is a limiting factor on a useable lifetime of the aerosol generation device. It is desirable to provide a heating element with improved lifetime, or a heating element which can be easily replaced while requiring minimal resources.

SUMMARY

According to a first aspect, the present disclosure provides an aerosol generation device configured to generate an aerosol from a consumable comprising aerosol substrate, the consumable further comprising a heating element comprising an electrically conductive material, the aerosol generation device comprising: a housing comprising a chamber adapted to hold the consumable; and an electrical supply surface comprising first and second comb-shaped electrodes, arranged in the chamber, wherein, when the heating element is located against the electrical supply surface, the first and second comb-shaped electrodes are configured to supply electricity through the electrically conductive material in order to heat the aerosol substrate.

By providing electrodes in the aerosol generation device and an electrically conductive material in the consumable, the heating element, such as a heating layer, is replaced with each consumable, and a simple interface is provided for supplying power to the heating element. Additionally, by providing comb-shaped electrodes, multiple current paths can be created through the heating element, in order to supply a required power to the heating element with a lower voltage.

Optionally, in the electrical supply surface, a plurality of teeth of the first comb shaped electrode interlock with a plurality of teeth of the second comb-shaped electrode. By interlocking the comb-shaped electrodes, a plurality of short current paths through the electrically conductive material are created, where each current path can be driven with a yet lower voltage.

Optionally, the electrical supply surface further comprises a third electrode isolated from the first electrode and configured to supply electricity through the electrically conductive material and the second electrode, wherein the first electrode and third electrode are configured to be individually activated to supply electricity through the electrically conductive material. By providing individually activated electrodes, a heating power can be varied by using any one or more pairings of the electrodes.

Optionally, the chamber comprises: a base housing portion and a lid housing portion configured to move between an open position at which the consumable can be inserted and removed and a closed position where the consumable is surrounded by the chamber. By providing a base and a lid, the consumable can be conveniently added to and removed from the aerosol generation device in the open position, while allowing for effective aerosol generation in the closed chamber environment.

Optionally, the electrical supply surface is split into a first part attached to the base housing portion and a second part attached to the lid housing portion, wherein the first and second parts of the electrical supply surface connect in the closed position. By providing two parts of the electrical supply surface which connect in the closed position, the aerosol generation device is configured to disable heating in the open, and may be automatically configured to begin heating automatically when the base and lid housing portions are moved to the closed position.

Optionally, the chamber comprises an air inlet and an air outlet configured to allow air to flow through the chamber. By allowing air to flow through the chamber, the aerosol can be actively drawn out of the consumable when it is generated.

Optionally, the electrical supply surface extends across the air inlet or the air outlet. With this configuration, air may flow close to the heat source and improve the efficiency of aerosol generation.

Optionally, the chamber comprises a plurality of electrical supply surfaces configured to supply electricity through different areas of the heating layer of the consumable. This may be used to improve uniformity and speed of aerosol generation in the consumable. Optionally, the chamber comprises a compression element configured to compress the consumable against the electrical supply surface. Compressing the consumable can improve the electrical contact between the electrical supply surface and the heating layer, and improve the efficiency of aerosol generation.

According to a second aspect, there is provided a consumable comprising an aerosol substrate wherein the consumable comprises a heating element comprising an electrically conductive material.

In a mode, the consumable comprises a body of aerosol substrate and the heating element is an outer heating layer positioned adjacent to the body.

Optionally, the body of aerosol substrate is surrounded by the heating layer around an axis.

Optionally, the heating layer fully encases the body of aerosol substrate.

Optionally, the electrically conductive material has a resistivity of at least 10⁵ W/m. Optionally, the electrically conductive material has a resistivity of about 10² Q/m.

Optionally, the electrically conductive material has an electrical conductivity of at least 300 S/m (at 20°C).

Optionally, the aerosol substrate comprises a loose material.

Optionally, the electrically conductive material of the consumable comprises carbon filament yarns such as Kynol, a pyrolytic graphite sheet, and/or particles of graphite and/or charcoal.

In another mode, the heating element is in the form of particles embedded in the aerosol substrate.

Optionally, the aerosol substrate comprises an aerosol forming agent and the electrically conductive material is arranged in the aerosol substrate to conduct electrical current between two electrodes and to heat the aerosol substrate to a temperature sufficient to aerosolize the aerosol forming agent. Optionally, a thickness of the aerosol substrate may be comprised between 0.5 and 3 mm, preferably between 0.5 and 2 mm.

Optionally, the particles of the heating element may be distributed in and on the aerosol substrate in an amount to allow electricity to flow between the two electrodes through the thickness of the aerosol substrate.

Optionally, the electrically conductive material may be randomly distributed inside the aerosol substrate and on a surface area of the aerosol substrate.

Optionally, the electrically conductive material is 2.5 to 50 wt.%, preferably between 2.5 and 25 wt.%, of the aerosol substrate. Optionally, the aerosol substrate further comprises a binder, preferably CMC (carboxymethyl cellulose), in an amount between 0.5 and 2.5 wt.% of the aerosol substrate.

Optionally, the aerosol forming agent is glycerin and/or propylene glycol.

Optionally, the aerosol forming agent is less than 25 wt.% of the aerosol substrate. Optionally, the aerosol substrate further comprises water in an amount between 10 and 49.5 wt.%.

Optionally, the aerosol substrate comprises tobacco in an amount up to 47.5 wt.%.

According to a third aspect, there is provided an aerosol generation system comprising an aerosol generating device according to the first aspect and a consumable according to the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1A and 1 B are schematic cross-sections of an aerosol generation system according to an embodiment of the invention; Figs. 2A and 2B are schematic diagrams of an electrical supply surface and its usage in embodiments of the invention;

Fig. 3 is a schematic diagram of an alternative electrical supply surface according to an embodiment;

Figs. 4A and 4B are schematic diagrams of an alternative aerosol generation system according to an embodiment of the invention;

Figs. 5A, 5B and 5C are further schematic diagrams of another alternative aerosol generation system according to an embodiment of the invention;

Fig. 6 is schematic cross-section of an aerosol generation system according to another embodiment of the invention.

DETAILED DESCRIPTION

Figs. 1A and 1 B are schematic cross-sections of an aerosol generation system comprising an aerosol generation device 1 and a consumable 2. Fig. 1 A illustrates the system in a loading state where the consumable 2 is being added for aerosol generation. Fig. 1B illustrates the system in a ready state where the consumable 2 is in position for aerosol generation.

The aerosol generation device 1 comprises a housing 11. In many embodiments, the housing 11 is configured to be handheld. The housing 11 may, for example, comprise a thermally insulating material. For example, the housing 11 may comprise a plastic such as polyetheretherketone (PEEK) in order to minimize wasted heat leaking from the aerosol generation device 1 , improve safety in cases where the device is handheld, and reduce the time and energy required to generate an aerosol.

The housing 11 defines an internal chamber 12 adapted to receive and hold the consumable 2. The housing 11 may be connected to a lid 13, for example via a hinge or a flexible attachment such as a string, where the lid is configured to move between an open position at which the consumable 2 can be inserted and removed from the chamber 12 and a closed position where the consumable 2 is surrounded by the chamber 12. As a result, the chamber 12 comprises a base housing portion formed in the housing 11 and a lid housing portion formed by the lid 13.

The aerosol generation device 1 also comprises an electrical supply surface 14 arranged in the chamber 12. Specifically, in this embodiment, the electrical supply surface 14 is arranged on a bottom surface of the chamber 12 opposite to an opening for receiving the consumable 2 into the chamber 12. More generally, the electrical supply surface 14 may be arranged on any surface of the chamber 12 including an inner surface of the lid 13.

The consumable 2 comprises an aerosol substrate 21 and a heating element 22. In this embodiment, the heating element 22 is a heating layer 22 adjacent to a body of the aerosol substrate. When the consumable 2 is inserted into the chamber 12, the heating element 22 is located against the electrical supply surface 14.

The aerosol substrate 21 may be any porous solid substrate suitable for generating and releasing an aerosol. The substrate may for example comprise a foam, a powder, packed strands or fibres. The substrate typically comprises a flavourant material such as for example nicotine or tobacco (e.g. in dried leaf or powder form) and an aerosol forming agent.

Tobacco may comprise tobacco powder with particle size lower than 1000 microns. The tobacco material may comprise flue cured tobacco (FCT) in an amount between 1 and 47.5% of the weight of the aerosol substrate 21.

Suitable aerosol forming agents include: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as monohydric alcohols, acids such as lactic acid, glycerol derivatives, esters such as triacetin, triethylene glycol diacetate, triethyl citrate, glycerin or vegetable glycerin. In some embodiments, the aerosol forming agent may be glycerol, propylene glycol, or a mixture of glycerol and propylene glycol. The aerosol forming agent may suitably comprise less than 25% of the weight of the aerosol substrate 21. The aerosol forming agent may suitably comprise more than 5% of the weight of the aerosol substrate.

The aerosol substrate 21 may further comprise a binder such as CMC (carboxymethyl cellulose). The binder may suitably comprise between 0.5% and 2.5% of the weight of the aerosol substrate.

The aerosol substrate 21 may further comprise water. The water may suitably comprise between 10% and 49.5% of the weight of the aerosol substrate.

A thickness of the aerosol substrate 21 may be between 0.5 and 3 mm, or more preferably between 0.5 and 2 mm.

The heating element 22 comprises an electrically conductive material. The electrically conductive material may be a metal such as gold. The electrically conductive material preferably has an electrical conductivity of at least 300 S/m (at 20°C). However, the heating element preferably has some substantial resistance in order to dissipate heat. For example, the electrically conductive material may be a material with a resistivity of at least 10⁵ W/m in a conduction direction through the material. This may be achieved using a conductive form of carbon such as carbon filament yarns (for example Kynol), a pyrolytic graphite sheet, or carbon particles of graphite and/or charcoal. In embodiments where the heating element 22 is a distinct heating layer 22, the heating layer 22 may take the form of a continuous plate or foil, and/or comprise discrete strips or a mesh of conductive material.

As shown further in Fig. 2B (described below), the heating element 22 is configured to complete an electrical circuit with the electrical supply surface 14 and supply heat to the aerosol substrate 21. Upon heating the aerosol substrate 21, a volatile component of the aerosol substrate 21 (such as the aerosol forming agent) vaporises and forms an aerosol.

The size of consumable 2 and the chamber 12 may in some embodiments be configured such that, when the lid 13 is in the closed position, the lid 13 acts as a compression element and compresses the consumable 2 against the electrical supply surface 14. This compression can improve electrical contact between the electrical supply surface 14 and the heating layer 22, and can also improve aerosol generation in the aerosol substrate 21.

The aerosol generation device further comprises an air flow channel 15 configured to take in air at an inlet 151, and direct the air through the chamber 12 to an outlet 152. As air flows through the chamber 12, the aerosol is added to the air and transferred to the outlet 152, at which a user can inhale the aerosol.

The air flow channel 15 intersects with the chamber 12 at an internal air inlet and air outlet of the chamber 12, which are configured to allow air to flow through the chamber 12. The aerosol substrate 21 is typically porous such that air can flow through the consumable 2 when the consumable is in place in the chamber 12. Additionally or alternatively, air may flow around the consumable 2 within the chamber 12.

The outlet 152 may in some embodiments be configured as a mouthpiece. Air may be driven through the air flow channel 15 by the user inhaling, or may be actively driven using a pump. The chamber 12 is preferably arranged near to the outlet 152 in order to reduce the length of a channel in which the aerosol is transported, and thereby reduce condensation of the aerosol within the aerosol generation device 1.

The aerosol generation device 1 also comprises control electronics for controlling supply of power to the electrical supply surface 14 (not shown). The aerosol generation device 1 may also comprise an internal power source (such as a battery), or a connector for an external power source. The aerosol generation device 1 may also comprise any of a temperature sensor configured to measure a temperature in the chamber 12, an air flow sensor configured to measure air flow through the airflow channel 15, and/or a user interface configured to display a status of the aerosol generation device 1 and/or to allow the user to control the aerosol generation system 1. Figs. 2A and 2B are schematic diagrams showing additional detail of the electrical supply surface 14 in one example. Fig. 2A is a top view showing the electrical supply surface 14 in a planar configuration on a surface of the chamber 12. Fig. 2B is a cross-section perpendicular to Fig. 2A, along the line x labelled in Fig. 2A, and additionally showing the heating layer 22 of the consumable 2 located against the electrical supply surface 14.

The electrical supply surface 14 comprises a first comb-shaped electrode 141 and a second comb-shaped electrode 142. The first and second comb-shaped electrodes define an electrical circuit gap which is closed when the heating element 22 of the consumable 2 is located against the electrical supply surface 14. Each of the first and second comb-shaped electrodes is connected to the control electronics in order to receive power. When a potential difference is applied between the first and second comb-shaped electrodes 141, 142, current is driven through the heating element 22, for example along the arrows shown in Fig. 2B.

Preferably, the first and second comb-shaped electrodes are arranged such that a plurality of teeth of the first comb-shaped electrode interlock with a plurality of teeth of the second comb-shaped electrode, as shown in Fig. 2A. In this way, a distance of conduction in the heating element 22 between the electrodes 141 , 142 is short, but an area of conduction in the heating element 22 extends across the area covered by the electrical supply surface 14. By reducing the distance of conduction in the heating element 22, a required potential difference between the first and second comb-shaped electrodes 141 , 142 can be reduced relative to other designs, and a small voltage of, for example, 3-4V can be used. In a comparative design, electrodes were located only at opposite ends of a heating layer, and a voltage of around 30V was required.

The comb-shaped electrodes 141 , 142 may be thin conductive tracks supported by an inner surface of the chamber 12. Alternatively, the electrical supply surface 14 may be a self-supporting module, including a base surface on which conductive tracks are located, or having thick conductive tracks which are themselves self- supporting. The comb-shaped electrodes 141 , 142 may, for example, comprise copper or gold tracks. Fig. 3 is a schematic diagram of an alternative electrical supply surface 14. Only the differences from the above electrical supply surfaces are described and it may be assumed that the electrical supply surfaces are otherwise similar.

In this embodiment, the electrical supply surface 14 further comprises a third electrode 143 isolated from the first electrode 141. The third electrode 143 is configured similarly to the first electrode 141 to supply electricity through the heating layer 22 and the second electrode 142. However, the first electrode 141 and third electrode 143 can be driven independently through separate electrical connections to the control electronics. This means that a rate of heating in the heating element 22 can be controlled by activating each of the first and second electrodes 141, 143 independently.

More generally, the electrical supply surface 14 may comprise any number of comb-shaped electrodes configured to supply power independently through the heating element 22.

Figs. 4A and 4B are schematic diagrams of an alternative aerosol generation system. Only the differences from the above aerosol generation systems are described and it may be assumed that the systems are otherwise similar. Fig. 4A is a cross-section perpendicular to a direction of air flow through the chamber 12. Fig. 4B is a flattened depiction which maps to the curved inner surface shown in cross-section in Fig. 4A.

In this alternative aerosol generation system of Figs. 4A and 4B, the electrical supply surface 14 is split across two surfaces of the chamber 12. More specifically, a first part of the electrical supply surface 14 is attached to the base housing portion 11 and a second part of the electrical supply surface 14 is attached to the lid housing portion 13. As shown in Fig. 4B, in the open position, the first and second comb-shaped electrodes 141, 142 are split. When the lid 13 is closed, the first and second parts of the electrical supply surface 14 connect together to form a structure similar to Fig. 2A. Additionally, Figs. 4A and 4B illustrate how the electrical supply surface 14 need not be flat, and can be a curved surface extending around the chamber 12 in which the consumable 2 is inserted.

Furthermore, in the alternative aerosol generation system of Figs. 4A and 4B, the heating layer 22 surrounds the aerosol substrate 21 around an axis. With this configuration, in the closed position, the heating layer 22 and the electrical supply surface 14 can be arranged concentrically around the aerosol substrate 21 to deliver heat more efficiently into the aerosol substrate 21.

Figs. 5A, 5B and 5C are further schematic diagrams of another alternative aerosol generation system. Fig. 5A is a cross-section similar to Figs. 1A and 1 B but showing a different arrangement of the electrical supply surface 14 and heating layer 22 as described below. Figs. 5B and 5C are schematic diagrams of an air inlet or air outlet 153 of the chamber 12 in the another alternative aerosol generation system.

In Fig. 1A, the airflow channel 15 intersects with the chamber 12 at an internal air inlet and air outlet which are configured to allow air to flow through the chamber 12. In the aerosol generation system of Figs. 5A, 5B and 5C, the heating components are connected across the air inlet or air outlet of the chamber 12.

More specifically, the first and second comb-shaped electrodes 141 , 142 extend across an opening 153 (the internal air inlet or air outlet), as shown in Fig. 5B. Air flow passes through the first and second comb-shaped electrodes 141 , 142 and through the heating layer 22 (which may be a porous, meshed or strip structure).

The housing 11 may comprise a grille structure across the opening 153 to support the first and second comb-shaped electrodes 141, 142, as shown in Fig. 5B. Alternatively, the first and second comb-shaped electrodes 141 , 142 may be freestanding across the opening 153. In either case, the gaps between the first and second comb-shaped electrodes 141 , 142 allow airflow. By directing airflow immediately adjacent to the heating in the heating layer 22 (as driven by the electrodes 141 , 142), aerosol generation may be localised close to air flow such that a greater proportion of generated aerosol is drawn out of the aerosol generation device 1.

As explained above, Figs. 4Ato 5C illustrate ways of increasing the surface area of heating using the electrical supply surface 14 and the heating layer 22. To further increase the efficiency of heating, one or more electrical supply surfaces 14 may cover all surfaces of the chamber 12 which come into contact with the consumable 2, such that each electrical supply surface 14 supplies electricity through a different area of the heating layer 22. The heating layer 22 may fully encase the body of aerosol substrate 21 for this purpose.

A heating layer 22 which fully encases the body of aerosol substrate 21 may also be used in other embodiments to improve convenience of inserting the consumable 2, since orientation is no longer relevant if the heating layer 22 is present on all external surfaces of the consumable 2.

A heating layer 22 which fully encases the body of aerosol substrate 21 may also be used in embodiments where the aerosol substrate 21 is a loose material such as a powder, in order to simultaneously provide a bag for the aerosol substrate 21.

Fig. 6 is a schematic diagram of a further alternative aerosol generation system. The alternative aerosol generation system is largely similar to the above- described examples, and only the differences are described.

As illustrated in Fig. 6, the heating element does not have to be a heating layer separate from a body of aerosol substrate. Instead, in this embodiment, the heating element is in the form of particles embedded in the aerosol substrate. For example, the particles may comprise graphite or charcoal. The particles are provided in a sufficient amount and/or size to allow electricity to flow via the particles between the first and second comb-shaped electrodes 141 , 142. Preferably, contact between particles is sufficient to conduct the current between the electrodes and/or particles are positioned at the surface of the substrate to contact the electrodes. Additionally, the amount of particles increases the conductivity of the aerosol substrate. This electricity flow dissipates heat due to the resistance of the aerosol substrate, and raises a temperature of the aerosol substrate sufficiently to aerosolize the aerosol forming agent. The consumable 1 may, in this example, be similar to the consumable described in co-pending European patent application No. 21161783.2 entitled “Electrically conductive consumable.” The particles are preferably small and homogeneously distributed (unlike in the schematic depiction of Fig. 6) such that the particles have an overall uniform effect on conductivity of the aerosol substrate, and a current through the substrate is reasonably predictable. The electrically conductive material may be randomly distributed inside the aerosol substrate and on a surface area of the aerosol substrate. The electrically conductive material may be 2.5% to 50% of the weight of the aerosol substrate 21.

Claims

1. An aerosol generation device configured to generate an aerosol from a consumable comprising aerosol substrate, the consumable further comprising a heating element comprising an electrically conductive material, the aerosol generation device comprising: a housing comprising a chamber adapted to hold the consumable; and an electrical supply surface comprising first and second comb-shaped electrodes, arranged in the chamber, wherein, when the heating element is located against the electrical supply surface, the first and second comb-shaped electrodes are configured to supply electricity through the electrically conductive material in order to heat the aerosol substrate.

2. An aerosol generation device according to claim 1 wherein, in the electrical supply surface, a plurality of teeth of the first comb-shaped electrode interlock with a plurality of teeth of the second comb-shaped electrode.

3. An aerosol generation device according to any preceding claim, wherein the electrical supply surface further comprises a third electrode isolated from the first electrode and configured to supply electricity through the electrically conductive material and the second electrode, wherein the first electrode and third electrode are configured to be individually activated to supply electricity through the electrically conductive material.

4. An aerosol generation device according to any preceding claim, wherein the chamber comprises: a base housing portion and a lid housing portion configured to move between an open position at which the consumable can be inserted and removed and a closed position where the consumable is surrounded by the chamber.

5. An aerosol generation device according to any preceding claim, wherein the chamber comprises an air inlet and an air outlet configured to allow air to flow through the chamber.

6. An aerosol generation device according to claim 5, wherein the electrical supply surface extends across the air inlet or the air outlet.

7. An aerosol generation device according to any preceding claim, wherein the chamber comprises a plurality of electrical supply surfaces configured to supply electricity through different areas of the heating element of the consumable.

8. An aerosol generation device according to any preceding claim, wherein the chamber comprises a compression element configured to compress the consumable against the electrical supply surface.

9. An aerosol generation system comprising an aerosol generating device according to any one of claims 1 to 8 and a consumable comprising aerosol substrate, the consumable further comprising a heating element comprising an electrically conductive material.

10. An aerosol generation system according to claim 9, wherein the consumable comprises a body of aerosol substrate and the heating element is an outer heating layer positioned adjacent to the body.

11. An aerosol generation system according to claim 10, wherein the body of aerosol substrate is surrounded by the heating layer around an axis.

12. An aerosol generation system according to claim 10 or claim 11 , wherein the heating layer fully encases the body of aerosol substrate.

13. An aerosol generation system according to any of claims 9 to 12, wherein the electrically conductive material has a resistivity of at least 10⁵ Q/m.

14. An aerosol generation system according to any of claims 9 to 13, wherein the aerosol substrate comprises a loose material.

15. An aerosol generation system according to any of claims 9 to 14, wherein the electrically conductive material comprises carbon filament yarns such as Kynol, a pyrolytic graphite sheet, and/or particles of graphite and/or charcoal.