EP3287021B1 - Heating elements for electronic cigarettes - Google Patents

Description

Field of invention

The invention relates generally to a heating element for hot applications. In particular, the invention relates to a heating element for the controlled heating and evaporation of vaporizable and / or tobacco-containing substances in electronic cigarettes.

Electronic cigarettes, also referred to as e-cigarettes in the following, are increasingly being used as an alternative to tobacco cigarettes. Typically, e-cigarettes have a mouthpiece and an evaporator unit comprising a heating element.

The heating element heats a vaporizable liquid so that it can be inhaled by the user. This liquid may already contain nicotine. Alternatively, the liquid is nicotine-free. The aerosol that forms can then flow through a nicotine-containing and nicotine-permeable body.

For example, lance-shaped heating elements are known from the prior art. These are inserted into a specially designed piece of tobacco and thus brought into contact with the substances to be vaporized and heat them to temperatures in the range from 50 ° C to 350 ° C. This leads to aerosol formation. Corresponding heating lances can consist of a heating wire without a carrier material. However, the disadvantage here is that due to the required mechanical stability of the heating element, the dimensions of the heating element cannot be made arbitrarily small. Furthermore, corresponding heating elements easily become soiled during use.

In the prior art, therefore, alternative heating lances are described whose heating conductor structures are applied to a carrier material. These heating lances have ceramic carrier materials, as these have electrical insulation in addition to high temperature stability. So in the EP 2 469 969 Described heating lances with carrier materials based on ZrO ₂ ceramics.

However, the disadvantage of using ceramic carrier materials is, in addition to the high production costs, their high surface roughness and porosity. Roughness and porosity have a disadvantageous effect on the heating conductor structures applied in the form of a conductive coating. The rough surface has a disadvantageous effect on the adhesion of the conductive coating to the carrier material.

Furthermore, the known ceramic carrier materials have a high thermal conductivity. This is disadvantageous for use in a heating element, since the heat generated in the heating area of the heating element cannot be given off in a targeted manner to the medium to be heated, but heat is dissipated through the ceramic and the heat thus dissipated is no longer for the Evaporation or heating of the substances is available. Correspondingly, more heating power must be applied by the heating element, which not only has a disadvantageous effect on energy consumption and thus, for example, the battery life of the e-cigarette, but also leads to a temperature increase inside the e-cigarette and is therefore disadvantageous can affect the life of the heating element.

In an alternative structure of an e-cigarette, the heating element can also be arranged inside the e-cigarette in such a way that it is not introduced directly into the tobacco piece or the substances to be vaporized, but rather the tobacco piece or a reservoir with the substances to be vaporized is cylindrical enclose. A corresponding arrangement is for example in the US 2005/0172976 described. Such external heating elements offer the advantage that the substances or tobacco pieces to be evaporated can be exchanged more easily.
Due to the desired small dimensions of the e-cigarettes, which are typically modeled on the dimensions of conventional tobacco cigarettes, such an arrangement of the heating element results in very small diameters and thus bending radii. Since the carrier material must also be an electrical insulator, only high-performance plastics such as polyimides or polyamides have so far been used as carrier material.

In these arrangements, the performance and service life of the heating element are limited by the relatively low temperature resistance of the plastics. In addition, the organic solvents used in the e-cigarette can lead to leaching effects. On the one hand, this is disadvantageous with regard to the service life of the heating element. In addition, components of the carrier material can be dissolved in the organic solvent and inhaled by the user.

A prior art heating element is off EP 2 316 286 A1 known that has a carrier made of any material, including ordinary glass.

Object of the invention

One object of the invention is therefore to provide a heating element, in particular for use in e-cigarettes, which, in addition to high heating performance and a long service life, can also be used in a large number of e-cigarettes with different structures.

Description of the invention

The object of the invention is already achieved by the subject matter of the independent claims. Advantageous embodiments and developments are the subject of the dependent claims.

The heating element according to the invention is particularly suitable for use in an e-cigarette and comprises at least one carrier material made of chemically hardened glass and metallic heating conductor structures.

The support material made of glass has a high temperature stability of more than 300 ° C or even more than 400 ° C. This is achieved, for example, when using glasses with a high glass transition temperature T _g .

At the same time, the carrier material has a very low thermal conductivity of <2 W / (K * m). The low thermal conductivity and the low heat capacity of the carrier material reduce or prevent the heat generated by the heating element from spreading in the carrier material and thus enable targeted heat conduction from the heating element to the substances to be evaporated. According to an advantageous embodiment of the invention, the carrier material has a thermal conductivity of <1.8 W / (K * m) or even <1.5 W / (K * m).

At the same time, the specific heat capacity of the carrier material is less than 1200 J / K * kg, preferably even less than 1000 J / K * kg. The low heat capacity ensures that the heat generated in the heating element is conducted quickly and as completely as possible to the substances to be evaporated. This is advantageous with regard to the energy requirement during the evaporation process. At the same time, excessive heating of the Heating element avoided, which has a beneficial effect on its service life.

von kleiner als 1800 J²/K²*m*s*kg oder sogar kleiner als 1500 J²/K²*m*s*kg, besonders bevorzugt sogar kleiner als 1200 J²/K²*m*s*kg, ganz besonders bevorzugt sogar kleiner als 1000 J²/K²*m*s*kg bei beispielhaften Temperaturen 20-100°C aufweist. Im Unterschied zum erfindungsgemäßen Trägermaterial weisen dagegen die bislang im Stand der Technik als Trägermaterialien beschriebenen Keramiken höhere Wärmeleitfähigkeiten bzw. Wärmekapazitäten auf. So liegen beispielsweise bei Al₂O₃-Keramiken die Wärmeleitfähigkeiten bei 20 -30 W/K*m und somit um Faktor 20 höher als bei den erfindungsgemäßen Trägermaterialien. ZrO₂ Keramiken weisen mit 2- 3 W/K*m immerhin noch um mindestens Faktor 1,5 höhere Werte gegenüber Glas auf.Thus, both a low thermal conductivity and a low thermal capacity of the carrier material are preferably necessary in order to achieve a good heating performance of the heating element. A further development of the invention therefore provides that the heating element has a FOM for the product of thermal conductivity and thermal capacity $$\mathrm{FOM}=\mathrm{Thermal\; conductivity}*\mathrm{specific}\mathrm{Heat\; capacity}$$

of less than 1800 J ² / K ² * m * s * kg or even less than 1500 J ² / K ² * m * s * kg, particularly preferably even less than 1200 J ² / K ² * m * s * kg, very particularly preferably even less than 1000 J ² / K ² * m * s * kg at exemplary temperatures of 20-100 ° C. In contrast to the carrier material according to the invention, however, the ceramics previously described as carrier materials in the prior art have higher thermal conductivities or heat capacities. For example, with Al ₂ O ₃ ceramics, the thermal conductivities are 20-30 W / K * m and thus a factor of 20 higher than with the carrier materials according to the invention. At 2-3 W / K * m, ZrO ₂ ceramics still show values at least 1.5 times higher than glass.

The carrier material ensures the mechanical stability of the heating element. Metallic heating conductor structures are applied to or on a surface of the carrier material. These can be applied to the carrier material in the form of a coating, for example. There the carrier material according to the invention has a very smooth surface and the roughness R _{a is} less than 500 nm or even less than 250 nm, particularly preferably even less than 20 nm, particularly good adhesion can be achieved between the carrier material and metallic heat conductor structures. This manifests itself, for example, in a high mechanical resistance of the heating element.

Due to the high mechanical strength of the carrier material used, it can be made correspondingly thin. This enables a particularly compact design of the heating element and of the entire e-cigarette.

In the production of the heating elements according to the invention, the glass can be brought into the desired shape or geometry by drawing processes. In addition to flexible adaptation of the carrier material to the respective structure of the e-cigarette, this also enables the heating elements to be manufactured inexpensively.

According to one embodiment of the invention, the carrier material is designed as a tube or rod with a diameter of <20 mm. The tube or the rod can have a round, ellipsoidal, three- or more-angled cross-section. The carrier material can also be designed in the form of a hollow glass profile. The corresponding glass tubes or rods can be obtained by drawing processes. In a further development of the embodiment, the glass tubes have a wall thickness of less than 5 mm. According to a further embodiment of the invention, the glass of the carrier material is designed as thin or extremely thin glass and has a thickness of less than 2000 μm, less than 1000 μm or even less than 500 μm. The carrier material can be designed as flat glass. It is even possible to use thin glasses with a thickness of less than 100 µm or even less than 50 µm as a carrier material.

In a further development of this embodiment, on the other hand, the thin glass is transferred into a glass roll with a diameter of <20 mm. This can be done, for example, by rolling up the corresponding flat glass. In this case, carrier materials in the form of thin glass rolls with a diameter of less than 10 mm can also be obtained.

In particular, silicate glasses, borosilicate glasses, aluminum silicate glasses or aluminum borosilicate glasses have proven to be glasses suitable for use as a carrier material. Glass ceramics developed therefrom via temperature treatment can also be used.

Borosilicate glasses such as Zn-Ti-borosilicate glasses, Zn-silicate glasses or even sodium silicate glasses with a high SiO ₂ content can also be used as silicate glasses.

One embodiment of the invention provides that alkali-containing borosilicate glasses with the following components (in% by weight) are used as carrier glass: SiO ₂ 70 to 85 B ₂ O ₃ 0 to 15 Al ₂ O ₃ 1 to 10 Na ₂ O 1 to 10 K ₂ O 0 to 5 CaO 0 to 5, preferably ≥ 0.1.

• Al₂O₃/Na₂O ≥ 1 mol-% und
• ∑SiO₂ + Al₂O₃ ≤ 82 mol-%

In a further embodiment of the invention, the glass contains the following components (figures in mol%): SiO ₂ 64 to 78 Al ₂ O ₃ 5 to 14 Na ₂ O 4 to 12 K ₂ O 0 to 5 MgO 0 to 14 CaO 1 to 12 ZrO ₂ 0 to 2 TiO ₂ 0 to 4.5 With

• Al ₂ O ₃ / Na ₂ O ≥ 1 mol% and
• ∑SiO ₂ + Al ₂ O ₃ ≤ 82 mol%

In a further embodiment of the invention, the glass contains the following components (data in% by weight): SiO ₂ 50 to 65 Al ₂ O ₃ 15 to 20 B ₂ O ₃ 0 to 6 Li ₂ O 0 to 6 Na ₂ O 8 to 15 K ₂ O 0 to 5 MgO 0 to 5 CaO 0 to 7, preferably 0 to 1 ZnO 0 to 4, preferably 0 to 1 ZrO ₂ 0 to 4 TiO ₂ 0 to 1, preferably essentially free of TiO ₂

In a further embodiment of the invention, the glass contains the following components (data in% by weight): SiO ₂ 30 to 85 B ₂ O ₃ 3 to 20 Al ₂ O ₃ 0 to 15 Na ₂ O 3 to 15 K ₂ O 3 to 15 ZnO 0 to 12 TiO ₂ 0.5 to 10 CaO 0 to 0.1

In a further embodiment of the invention, the glass contains the following components (data in% by weight): SiO ₂ 55 to 75 Na ₂ O 0 to 15 K ₂ O 2 to 14 Al ₂ O ₃ 0 to 15 MgO 0 to 4 CaO 3 to 12 BaO 0 to 15 ZnO 0 to 5 TiO ₂ 0 to 2

In a further embodiment of the invention, the glass contains the following components (data in% by weight): SiO ₂ 50 to 70 Na ₂ O 0 to 5 K ₂ O 0 to 5 Al ₂ O ₃ 17 to 27 MgO 0 to 5 BaO 0 to 5 SrO 0 to 5 ZnO 0 to 5 TiO ₂ 0 to 5 ZrO ₂ 0 to 5 Ta ₂ O ₅ 0 to 8 P ₂ O ₅ 0 to 10 Fe ₂ O ₃ 0 to 5 CeO ₂ 0 to 5 Bi ₂ O ₃ 0 to 3 WHERE ₃ 0 to 3 MoO ₃ 0 to 3

As well as customary refining agents such as SnO ₂ , SO ₄ , Cl, As ₂ O ₃ , Sb ₂ O ₃ in amounts of 0 to 4% by weight

In particular, alkali-containing aluminosilicates can be chemically hardened by ion exchange and the mechanical stability of the carrier material can thus be increased further. In particular, the probability of breakage can be significantly reduced. Because of the high glass transition temperature T _{g of} the glasses of over 600 ° C., the ion exchange can take place at temperatures of over 400 ° C. so that only a short ion exchange time is required. The invention therefore provides that the carrier material is a chemically hardened glass.

This is particularly advantageous in the case of carrier materials based on thin or extremely thin glasses. For example, flat or ultra-flat carrier components with a thickness in the range from 0.1 to 0.5 mm can be obtained using a down-draw or overflow fusion process and chemically hardened without further prior thinning.

Alternatively or in addition, the mechanical strength of the carrier component can be achieved by chemical and / or mechanical edge processing, such as, for example.

Contouring or edge etching can be further increased. A development of the invention therefore provides that the edges of the carrier component are processed chemically and / or mechanically. This is particularly advantageous in the case of heating elements with carrier components made of alkali-free glasses, since there cannot be an increase in mechanical strength through ion exchange. The use of alkali-free glasses, for example alkali-free aluminoborosilicate glasses, as the carrier material is particularly advantageous because of their high chemical resistance and good processability, in particular the possibility of being able to draw the corresponding glasses into ultra-thin shapes.

The heating conductor structures can, for example, be applied in a spiral or meandering manner to the surface of the carrier material. Another embodiment of the invention provides for the heating conductor structures to be applied over the entire surface of the carrier material.

In the case of a tubular carrier material, depending on the configuration of the heating element or the corresponding e-cigarette, the heating conductor structures can be applied to the inner or the outer jacket surface of the carrier material.

According to one embodiment of the invention, the heating conductor structures are applied to the surface of the carrier material in the form of an electrically conductive coating, preferably as a platinum-containing coating or ITO coating.

Detailed description of the invention

• Fig. 1 eine graphische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Heizelements, bei welchem das Trägermaterial rohrförmig ausgebildet ist und sich die Heizleiterstrukturen auf der äußeren Mantelfläche des Rohrs befinden,
• Fig. 2 eine graphische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Heizelements, bei welchem das Trägermaterial stabförmig ausgebildet ist
• Fig. 3 eine graphische Darstellung eines weiteren Ausführungsbeispiels, bei welchem das Trägermaterial als Flachglas ausgebildet ist und meanderförmige Heizleiterstrukturen aufweist,
• Fig. 4 eine graphische Darstellung eines weiteren Ausführungsbeispiels, bei welchem das Trägermaterial als Flachglas ausgebildet ist und vollflächige Heizleiterstrukturen aufweist und
• Fig. 5 den schematischen Aufbau einer elektronischen Zigarette.

The invention is based on exemplary embodiments and the Figures 1 to 5 explained in more detail. Show it:

• Fig. 1 a graphic representation of an embodiment of a heating element according to the invention, in which the carrier material is tubular and the heating conductor structures are located on the outer jacket surface of the tube,
• Fig. 2 a graphical representation of an embodiment of a heating element according to the invention, in which the carrier material is rod-shaped
• Fig. 3 a graphic representation of a further embodiment, in which the carrier material is designed as flat glass and has meander-shaped heating conductor structures,
• Fig. 4 a graphical representation of a further embodiment in which the carrier material is designed as flat glass and has full-surface heating conductor structures and
• Fig. 5 the schematic structure of an electronic cigarette.

Embodiments

Tables 1 to 3 show 11 different exemplary embodiments or comparative examples for the carrier material used. The individual exemplary embodiments differ in terms of the composition of the glass. Examples 1 to 5 listed in Table 1 contain alkali ions and can be chemically hardened; Examples 6 and 7 listed in Table 2 are alkali-free glasses as comparative examples. Here, for example, the mechanical strength can be increased further by means of chemical and / or mechanical edge processing. Table 1: Alkali-containing examples component Example 1 wt% Example 2 wt% Example 3 wt.% Example 4 mol% Example 5 mol% SiO ₂ 81 79 75 68.5 68.2 B ₂ O ₃ 12.7 10 10 Al ₂ O ₃ 2.4 4th 6th 12 11.8 Na ₂ O 3.5 5 7th 12 10.5 K ₂ O 0.6 1 0 0.5 0 MgO 1.2 CaO 0 1 1.5 5 5.2 TiO ₂ 1.5 3.1 ZrO ₂ 0.5 0 α _20-300 [ppm / K] 3.3 * 10 ^-6 4 * 10 ^-6 4, 9 * 10 ^-6 7.6 * 10 ^-6 6.8 * 10 ^-6 Tg [° C] 525 555 565 642 685 Density [g / cm3] 2.2 2.3 2.34 2.46 2.47 Thermal conductivity @ 90 ° C [W m-1 K-1] 1.3 1.1 1.2 1.0 1.0 Mean specific heat capacity Cp at 20-100 ° C [J / (K * g)] 0.82 component Comparative example 6 wt.% Comparative example 7 wt% SiO ₂ 60 61 B ₂ O ₃ 4.5 0.5 Al ₂ O ₃ 14th 16.2 MgO 2.5 CaO 10 13 BaO 9 8th ZrO ₂ 1 α _20-300 [ppm / K] 4.6 * 10 ^-6 4.7 * 10 ^-6 Tg [° C] 720 790 Density [g / cm3] 2.63 2.67 Thermal conductivity @ 90 ° C [W m-1 K-1] 1.1 1.1 component Comparative example 8 wt% Example 9 wt% Example 10% by weight Example 11% by weight SiO ₂ 61 60.7 64.0 64 - 74 B ₂ O ₃ 10 8.3 Al ₂ O ₃ 18th 16.9 4.0 Na ₂ O 12.2 6.5 6-10 K ₂ O 4.1 7.0 6-10 MgO 2.8 3.9 CaO 4.8 5 - 9 BaO 3.3 0-4 ZrO ₂ 1.5 SnO ₂ 0.4 CeO ₂ 0.3 ZnO 5.5 2 - 6 TiO ₂ 4.0 0 - 2 Sb ₂ O ₃ 0.6 Cl 0.1 α _20-300 [ppm / K] 3.2 x 10 ^-6 7.2 x 10 ^-6 9.4 x 10 ^-6 Tg [° C] 717 557 553 Density [g / cm3] 2.43 2.5 2.55 Thermal conductivity @ 90 ° C [W m-1 K-1] 1.16 Mean specific heat capacity Cp at 20-100 ° C [J / (K * g)] 0.8

Fig. 1 shows a graphic representation of an embodiment of a heating element 1 according to the invention, in which the carrier material 2 is tubular. In this exemplary embodiment, the heating conductor structures 3 are located on the outer jacket surface 4 of the tube 2 and are arranged in a spiral. The glass tube 2 has a diameter 5 of less than 20 mm, the wall thickness of the tube is less than 5 mm. Due to the cavity 6, the heating element 1 is suitable, for example, for use as an externally adjacent, cylindrical heating element for so-called heat-not-burn cigarettes.

The in Fig. 1 The structure shown for the heating element 1 can also be implemented with an ultra-thin glass as the carrier material. A corresponding ultra-thin glass, for example an alkali aluminosilicate glass, can initially be provided as flat glass. In a subsequent one In the manufacturing step, the glass can be provided with heat conductor structures 3 and rolled up to form a tube.

In Fig. 2 a further embodiment of the heating element 1 is shown schematically. According to this embodiment, the carrier material 2a is designed in the form of a glass rod with a diameter of less than 20 mm. The heat conductor structures 3 are applied as a spiral coating on the surface of the carrier material 2a. The ends 7 of the carrier material 2a are flat in the embodiment shown here. The carrier material 2a can, however, also have round or pointed ends, depending on the requirements placed on the design of the heating element. A different geometrical configuration of the two ends of the carrier material 2a is also possible.

Fig. 3 shows a graphic representation of a further exemplary embodiment in which the carrier material 2c is designed as flat glass and has meander-shaped heating conductor structures 3. The carrier material is formed into a point at one end. This enables, for example, the in Fig. 3 introduce heating elements shown in a piece of tobacco.

The heat conductor structures 3 can be connected to an energy source (not shown) via the contacts 8a and 8b. In the Fig. 3 The embodiment shown can also be implemented with ultra-thin flat glasses as the carrier material 2c. Glass thicknesses of less than 100 µm or even less than 50 µm are possible here.

Fig. 4 FIG. 11 shows a graphic representation of a further exemplary embodiment in which the carrier material 2d is designed as flat glass and has full-area heating conductor structures 3. The carrier material is formed into a point at one end. This enables, for example, the in Fig. 4 introduce heating elements shown in a piece of tobacco.

In Fig. 5 an electronic cigarette 9 is shown. The cigarette 9 comprises a tip 10 and a mouthpiece 19 on which the user pulls in order to inhale the aerosol generated in the cigarette by means of a vaporizer 15. According to a preferred embodiment of the invention, the mouthpiece 19 can be removed from the tip 10.

The cigarette 9 contains an electrical energy store 12 in order to provide the electrical energy for vaporising the organic liquid in the vaporizer 12. In the embodiment shown, the electrical energy store 12 is accommodated in the tip 10 of the cigarette 9.

The electronic cigarette 9 also contains a control unit 13 which regulates the heating power of the heating element in the vaporizer 15. In particular, the control unit 13 can be set up to determine whether a user is inhaling and to regulate the heating power of the heating element 16 as a function thereof.

A light-emitting diode 11, which is also controlled by the control unit 13, can also be arranged in the tip 10. If the control unit 13 registers that the user is drawing on the cigarette 9, it can control the light-emitting diode 11 so that the light-emitting diode 11 lights up. This creates a visual effect similar to the glow when you draw on a conventional cigarette.

The vaporizer unit 15 comprises a liquid storage unit 17 and an organic carrier liquid 18 accommodated therein The heating element 16 is supplied with power from the electrical energy store 12 in a controlled manner via the control unit 13. By heating to an operating temperature greater than 100 ° C., the organic carrier liquid 18, in particular a high-boiling alcohol such as glycerine or propylene glycol, which has been taken up, can be evaporated.

Glass or glass ceramic rod formed with a diameter of less than 20 mm. The heat conductor structures 3 are applied as a spiral coating on the surface of the carrier material 2a. The ends 7 of the carrier material 2a are flat in the embodiment shown here. The carrier material 2a can, however, also have round or pointed ends, depending on the requirements placed on the design of the heating element. A different geometrical configuration of the two ends of the carrier material 2a is also possible.

Fig. 3 shows a graphic representation of a further exemplary embodiment in which the carrier material 2c is designed as flat glass and has meander-shaped heating conductor structures 3. The carrier material is formed into a point at one end. This enables, for example, the in Fig. 3 introduce heating elements shown in a piece of tobacco.

The heat conductor structures 3 can be connected to an energy source (not shown) via the contacts 8a and 8b. In the Fig. 3 The embodiment shown can also be implemented with ultra-thin flat glasses as the carrier material 2c. Glass thicknesses of less than 100 µm or even less than 50 µm are possible here.

Fig. 4 FIG. 11 shows a graphic representation of a further exemplary embodiment in which the carrier material 2d is designed as flat glass and has full-area heating conductor structures 3. The carrier material is formed into a point at one end. This enables, for example, that in Fig. 4 introduce heating elements shown in a piece of tobacco.

In Fig. 5 an electronic cigarette 9 is shown. The cigarette 9 comprises a tip 10 and a mouthpiece 19 on which the user pulls in order to inhale the aerosol generated in the cigarette by means of a vaporizer 15. According to a preferred embodiment of the invention, the mouthpiece 19 can be removed from the tip 10.

The cigarette 9 contains an electrical energy store 12 in order to provide the electrical energy for vaporising the organic liquid in the vaporizer 12. In the embodiment shown, the electrical energy store 12 is accommodated in the tip 10 of the cigarette 9.

The electronic cigarette 9 also contains a control unit 13 which regulates the heating power of the heating element in the vaporizer 15. In particular, the control unit 13 can be set up to determine whether a user is inhaling and to regulate the heating power of the heating element 16 as a function thereof.

A light-emitting diode 11, which is also controlled by the control unit 13, can also be arranged in the tip 10. If the control unit 13 registers that the user is drawing on the cigarette 9, it can control the light-emitting diode 11 so that the light-emitting diode 11 lights up. This creates an optical effect corresponding to that Glowing achieved when drawing on a conventional cigarette.

The vaporizer unit 15 comprises a liquid storage unit 17 and an organic carrier liquid 18 accommodated therein The heating element 16 is supplied with power from the electrical energy store 12 in a controlled manner via the control unit 13. By heating to an operating temperature greater than 100 ° C., the organic carrier liquid 18, in particular a high-boiling alcohol such as glycerine or propylene glycol, which has been taken up, can be evaporated.

Claims (20)

1. A heating element (1, 16) for use in an electronic cigarette (9), comprising at least one carrier material (2, 2a, 2c, 2d) made of chemically toughened glass and metallic heating conductor structures (3), wherein the heating conductor structures (3) are applied on the carrier material (2, 2a, 2c, 2d) and the carrier material (2, 2a, 2c, 2d) has a thermal conductivity of < 2 W/K*m, a thermal capacity of < 1000 J/K*kg. and a roughness R_a of < 500 nm.
2. The heating element (1, 16) according to the preceding claim, wherein the carrier material has a thermal conductivity of < 1.8 W/K*m, preferably < 1.5 W/K*m.
3. The heating element (1, 16) according to any one of the preceding claims, wherein the carrier material (2, 2a) is tubular or rod-shaped and preferably has a diameter (5) of < 20 mm and/or a wall thickness of < 5 mm.
4. The heating element (1, 16) according to the preceding claim, wherein the carrier material (2) is in the form of a glass tube (2) with a triangular or polygonal cross-sectional shape.
5. The heating element (1, 16) according to any one of claims 1 to 2, wherein the carrier material (2) has a tubular shape with a round or ellipsoidal cross-sectional shape, or is in the form of a hollow glass profile.
6. The heating element (1, 16) according to any one of the preceding claims, wherein the carrier material (2, 2c, 2d) is made from a thin glass, preferably from a thin glass having a thickness of < 2000 µm, preferably < 1000 µm, most preferably ≤ 500 µm.
7. The heating element (1, 16) according to any one of the preceding claims, wherein the carrier material (2c, 2d) is made from a thin glass, preferably from a thin glass having a thickness of < 100 µm, preferably < 50 µm.
8. The heating element (1, 16) according to the preceding claim, wherein the thin glass is rolled or can be rolled to form a roll having a diameter of < 20 mm, preferably < 10 mm.
9. The heating element (1, 16) according to any one of the preceding claims, wherein the carrier material (2, 2a, 2c, 2d) is any of a silicate glass, a borosilicate glass, an aluminum silicate glass, or an aluminum borosilicate glass.
10. The heating element (1, 16) according to any one of claims 1 to 9, wherein the carrier material (2, 2a, 2c, 2d) is a glass including the following constituents (in wt%): SiO₂ 70 to 85 B₂O₃ 0 to 15 Al₂O₃ 1 to 10 Na₂O 1 to 10 K₂O 0 to 5 CaO 0 to 5, preferably ≥ 0.1.
11. The heating element (1, 16) according to the preceding claim, wherein the product of thermal conductivity and heat capacity, $$\mathrm{FOM}=\mathrm{thermal}\mathrm{conductivity}*\mathrm{specific}\mathrm{heat}\mathrm{capacity},$$

    

    is less than 1800 J²/K²*m*s*kg or even less than 1500 J²/K²*m*s*kg, preferably less than 1200 J²/K²*M*s*kg, in a temperature interval from 20 °C to 100 °C.
12. The heating element (1, 16) according to any one of the preceding claims, wherein the edges of the thin glass have been processed chemically and/or mechanically.
13. The heating element (1, 16) according to any one of the preceding claims, wherein the carrier material (2, 2a, 2c, 2d) has a roughness of less than 250 nm, preferably < 20 nm.
14. The heating element (1, 16) according to any one of the preceding claims, wherein the heating conductor structures (3) are in the form of an electrically conductive coating, preferably a platinum-containing coating or an ITO-based coating.
15. The heating element (1, 16) according to any one of the preceding claims, wherein the heating conductor structures (3) are arranged on the surface of the carrier material (2, 2a, 2c) in a helical or meandering pattern.
16. The heating element (1, 16) according to any one of the preceding claims 1 to 15, wherein the heating conductor structures (3) are disposed on the entire surface of the carrier material (2d).
17. The heating element (1, 16) according to any one of the preceding claims, wherein the heating conductor structures (3) are disposed on the outer lateral surface (4) of the carrier material (2).
18. The heating element (1, 16) according to any one of the preceding claims 1, 2, 6 to 7, or 9 to 17, wherein the carrier material (2) has a tubular shape and the heating conductor structures (3) are disposed on the inner lateral surface of the carrier material (2).
19. The heating element (1, 16) according to any one of the preceding claims 1, 2, 6 to 7, or 9 to 15, wherein the carrier material (2c, 2d) is in the form of sheet glass.
20. Use of a heating element (1, 16) according to any one of the preceding claims in an electronic cigarette (9).

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