Method and apparatus for producing inner liners for packets of aerosol-generating or smoking articles

Abstract

An apparatus for producing inner liners for packets of aerosol-generating articles or smoking articles comprises a heating unit (22, 23, 24) positioned downstream of a feeder (11, 11') of a continuous sheet (13, 13') comprising a metal layer (14) and a coating layer (15) with a flavor, an embossing and punching unit (10) configured to emboss and punch the continuous sheet (13, 13') to form individual inner liners (5). The heating unit ((22, 23, 24) comprises an induction heating unit (24) comprising: an alternate voltage generator (25), first electrodes (26) connected to a first terminal (27) of the alternate voltage generator (25), second electrodes (28) connected to a second terminal (29) of the alternate voltage generator (25). The first electrodes (26) and the second electrodes (28) are arranged side by side on one side of a lying plane of the continuous sheet (13, 13'). The induction heating unit (24) is configured to generate an oscillating electrical field (E) inducing currents in the metal layer (14) and heating the metal layer (14) by Joule effect, wherein the generated heat heats up the coating layer (15).

Description

[0001] METHOD AND APPARATUS FOR PRODUCING INNER LINERS FOR PACKETS OF AEROSOL-GENERATING OR SMOKING ARTICLES

[0002] The present disclosure relates to the packaging of aerosol-generating articles or heat- not-burn cigarettes (RRP - Reduced Risk Product) and also of burning smoking articles, like conventional cigarettes. Particularly, the present disclosure relates to a method and to an apparatus for producing flavoured inner liners for packets of aerosol-generating or smoking articles.

[0003] Aerosol-generating articles or heat-not-burn cigarettes, in which an aerosolgenerating substrate is heated rather than combusted, are known in the art. Typically, in such heated aerosol-generating articles, an aerosol is generated by the transfer of heat from a heat source to the physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] The inner liner is a protective laminated paper having a metallic layer of aluminum or other suitable metal which encloses the aerosol-generating or smoking articles (the aluminum layer towards the outside, the paper towards the articles) and that is inserted in the packet.

[0005] One of the major requests of heat-not-burn cigarettes consumers as well as conventional cigarettes consumers is to have strong flavour, particularly a strong menthol perception. Menthol may be included as pure menthol in the sensorial media substrate of heat-not-burn cigarettes (i.e., the substrate providing nicotine aerosol when heated), embedded inside tobacco cut filler, sprayed as mentholated flavour additive.

[0006] However, due to the request of having even more menthol perception, some products include menthol in the packaging. According to a known process and apparatus, a mentholated inner liner sheet provided in bobbin is unwound and embossed before being used to wrap a group of articles. After unwinding and before embossing and wrapping, the inner liner sheet goes into a heating chamber and then the heated inner liner sheet turns around a heated roller to then proceed to downstream process steps. In the heating chamber and on the heated roller, the inner liner sheet is heated by contact with heated surfaces (conduction and radiation heating). The mentholated inner liner is heated up to prevent or at least decrease solid menthol deposition on downstream elements of the apparatus which, after some time, may lead to machine stop for maintenance and cleaning operations.

[0007] Public document US2007277838 is also known, which discloses a cigarette manufacturing apparatus having an applicator for applying an aroma chemical to a wrapping paper continuously supplied along a supply path and a high-frequency dielectric heating device that dries the wrapping paper applied with the aroma chemical. The wrapping paper is then wrapped around tobacco shreds placed on the wrapping paper. The high-frequency dielectric heating device has a plurality of electrode pairs arranged opposite each other at a prescribed distance across a travel line for the wrapping paper.

[0008] Document US20040139702A1 discloses a method for making a packaging material for cigarettes in which a foil comprising oxide layers on each surface is fed to a coating application device where a cross-linkable monomer is applied to a first major surface of the foil. The coated foil is then fed to a curing device where the monomer coating is irradiated with UV light or electron beam radiation to polymerize the monomer and form the crosslinked polymer coating.

[0009] Document CN209555660U discloses a cigarette lining paper used to package cigarettes and cigarette packs.

[0010] Document CN216100825U discloses an inner lining paper for cigarette box packaging.

[0011] In this technical field, it would be desirable to have a method and an apparatus for producing flavoured inner liners for packets of aerosol-generating or smoking articles that allows to guarantee and / or improve the aroma or flavour perception of the user.

[0012] It would be desirable to ensure that most of the aroma or flavor that has been deposited on the inner liner sheet remains on said inner liner sheet until final packing of the aerosol-generating or smoking articles.

[0013] It would be desirable to improve fixing of the flavor on the laminated paper of the inner liner sheet.

[0014] It would be desirable to decrease the amount of aroma or flavor deposited on elements of the packaging apparatus, like rollers and conveyors, during the packaging process.

[0015] It would be desirable to reduce the occurrences of apparatus cleaning and / or maintenance operations and machine downtime.

[0016] It would be desirable to increase reliability of the apparatuses for packaging of aerosol-generating articles or heat-not-burn cigarettes.

[0017] The present disclosure relates to an apparatus for producing inner liners for packets of aerosol-generating or smoking articles. The apparatus for producing inner liners may comprise a feeder of a continuous sheet. The continuous sheet may comprise at least a metal layer and a coating layer comprising a flavor. The apparatus for producing inner liners comprises a heating unit positioned downstream of the feeder, with respect to a conveying direction of the continuous sheet, and along a conveying path. The heating unit is configured to heat the continuous sheet to stabilize the coating layer on the continuous sheet. The apparatus for producing inner liners may comprise an embossing and punching unit positioned downstream of the heating unit and configured to emboss and punch the continuous sheet to form individual inner liners. The heating unit comprises a induction heating unit. The heating unit comprises: an alternate voltage generator; at least one first electrode connected to a first terminal of the alternate voltage generator; at least one second electrode connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The at least one first electrode and the at least one second electrode are all arranged on one side of a lying plane of the continuous sheet traveling along the conveying path. The induction heating unit is configured to generate an oscillating electrical field which induces currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0018] The present disclosure relates to a method for producing inner liners for packets of aerosol-generating or smoking articles. The method for producing inner liners may comprise: feeding a continuous sheet along a conveying path and in a conveying direction. The method for producing inner liners comprises: heating the continuous sheet to stabilize the coating layer on the continuous sheet. The continuous sheet comprises a metal layer and a coating layer comprising a flavor. The method for producing inner liners comprises: embossing and punching the continuous sheet to form individual inner liners. Heating the continuous sheet comprises: moving the continuous sheet close to at least one first electrode and at least one second electrode all arranged on one side of the continuous sheet traveling along the conveying path. The at least one first electrodes is connected to a first terminal of an alternate voltage generator and the at least one second electrode are connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The method for producing inner liners comprises: applying an alternating voltage to the at least one first electrode and the at least one second electrode through the alternate voltage generator to generate an oscillating electrical field inducing currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0019] The present disclosure relates to a method for producing inner liners for packets of aerosol-generating or smoking articles, wherein the method for producing inner liners is carried out through an apparatus for producing inner liners for packets of aerosol-generating or smoking articles. The apparatus for producing inner liners may comprise a feeder of a continuous sheet. The continuous sheet may comprise at least a metal layer and a coating layer comprising a flavor. The apparatus may be configured to work the continuous sheet comprising the at least a metal layer and the coating layer comprising the flavor. The apparatus for producing inner liners comprises a heating unit positioned downstream of the feeder, with respect to a conveying direction of the continuous sheet, and along a conveying path. The heating unit is configured to heat the continuous sheet to stabilize the coating layer on the continuous sheet. The apparatus for producing inner liners may comprise an embossing and punching unit positioned downstream of the heating unit and configured to emboss and punch the continuous sheet to form individual inner liners. The heating unit comprises an induction heating unit. The heating unit comprises: an alternate voltage generator; at least one first electrode connected to a first terminal of the alternate voltage generator; at least one second electrode connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The at least one first electrode and the at least one second electrode are all arranged on one side of a lying plane of the continuous sheet traveling along the conveying path. The induction heating unit is configured to generate an oscillating electrical field which induces currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0020] The present disclosure relates to an apparatus for packaging aerosol-generating or smoking articles. The apparatus for packaging comprises an apparatus for producing inner liners for packets of aerosol-generating or smoking articles. The apparatus for producing inner liners may comprise a feeder of a continuous sheet. The continuous sheet may comprise at least a metal layer and a coating layer comprising a flavor. The apparatus for producing inner liners comprises a heating unit positioned downstream of the feeder, with respect to a conveying direction of the continuous sheet, and along a conveying path. The heating unit is configured to heat the continuous sheet to stabilize the coating layer on the continuous sheet. The apparatus for producing inner liners may comprise an embossing and punching unit positioned downstream of the heating unit and configured to emboss and punch the continuous sheet to form individual inner liners. The heating unit comprises an induction heating unit. The heating unit comprises: an alternate voltage generator; at least one first electrode connected to a first terminal of the alternate voltage generator; at least one second electrode connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The at least one first electrode and the at least one second electrode are all arranged on one side of a lying plane of the continuous sheet traveling along the conveying path. The induction heating unit is configured to generate an oscillating electrical field which induces currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0021] The present disclosure relates to a method for packaging aerosol-generating or smoking articles. The method for packaging comprises a method for producing inner liners for packets of aerosol-generating or smoking articles. The method for producing inner liners may comprise: feeding a continuous sheet along a conveying path and in a conveying direction. The method for producing inner liners comprises: heating the continuous sheet to stabilize the coating layer on the continuous sheet. The continuous sheet comprises a metal layer and a coating layer comprising a flavor. The method for producing inner liners comprises: embossing and punching the continuous sheet to form individual inner liners. Heating the continuous sheet comprises: moving the continuous sheet close to at least one first electrode and at least one second electrode all arranged on one side of the continuous sheet traveling along the conveying path. The at least one first electrodes is connected to a first terminal of an alternate voltage generator and the at least one second electrode are connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The method for producing inner liners comprises: applying an alternating voltage to the at least one first electrode and the at least one second electrode through the alternate voltage generator to generate an oscillating electrical field inducing currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0022] The present disclosure relates to a packet of aerosol-generating or smoking articles. The packet of aerosol-generating or smoking articles is made through an apparatus for packaging aerosol-generating or smoking articles. The apparatus for packaging comprises an apparatus for producing inner liners for packets of aerosol-generating or smoking articles. The apparatus for producing inner liners may comprise a feeder of a continuous sheet. The continuous sheet may comprise at least a metal layer and a coating layer comprising a flavor. The apparatus for producing inner liners comprises a heating unit positioned downstream of the feeder, with respect to a conveying direction of the continuous sheet, and along a conveying path. The heating unit is configured to heat the continuous sheet to stabilize the coating layer on the continuous sheet. The apparatus for producing inner liners may comprise an embossing and punching unit positioned downstream of the heating unit and configured to emboss and punch the continuous sheet to form individual inner liners. The heating unit comprises an induction heating unit. The heating unit comprises: an alternate voltage generator; at least one first electrode connected to a first terminal of the alternate voltage generator; at least one second electrode connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The at least one first electrode and the at least one second electrode are all arranged on one side of a lying plane of the continuous sheet traveling along the conveying path. The induction heating unit is configured to generate an oscillating electrical field which induces currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0023] The packet of aerosol-generating or smoking articles is made through a method for packaging aerosol-generating or smoking articles. The method for packaging comprises a method for producing inner liners for packets of aerosol-generating or smoking articles. The method for producing inner liners may comprise: feeding a continuous sheet along a conveying path and in a conveying direction. The method for producing inner liners comprises: heating the continuous sheet to stabilize the coating layer on the continuous sheet. The continuous sheet comprises a metal layer and a coating layer comprising a flavor. The method for producing inner liners comprises: embossing and punching the continuous sheet to form individual inner liners. Heating the continuous sheet comprises: moving the continuous sheet close to at least one first electrode and at least one second electrode all arranged on one side of the continuous sheet traveling along the conveying path. The at least one first electrodes is connected to a first terminal of an alternate voltage generator and the at least one second electrode are connected to a second terminal of the alternate voltage generator. The at least one first electrode and the at least one second electrode are arranged side by side. The method for producing inner liners comprises: applying an alternating voltage to the at least one first electrode and the at least one second electrode through the alternate voltage generator to generate an oscillating electrical field inducing currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0024] The aerosol-generating or smoking articles may be heat-not-burn cigarettes (RRP - Reduced Risk Product) or conventional burning articles.

[0025] The inventor found that the disclosed apparatus and method for producing inner liners, in particular the disclosed arrangement of the heating unit, allow to heat up effectively the coating layer with the flavor and to promote transition of the flavor to an amorphous state. The transition to the amorphous state makes the flavor more stable on the inner liner. Indeed, the alternating electrical field generated by the electrodes provides an induction heating for the flavor coating, heating the flavor so that it reaches the amorphous state decreasing the risk that the flavor loses solid parts. The inventor found that the induction heating allows to provide homogeneous heating to the coating layer which uniformly reaches a desired temperature.

[0026] The inventor found that the disclosed arrangement of the heating unit decreases the chances of the flavor of the coating layer separating and settling on parts and elements of the apparatus for producing inner liners and of the apparatus for packaging.

[0027] The inventor found that the disclosed apparatus and method for producing inner liners reduce the cleaning and / or maintenance operations and the machine downtime and improve the reliability of the apparatuses.

[0028] The inventor found that the disclosed apparatus and method for producing inner liners allow to manufacture packets of aerosol-generating or smoking articles that guarantee and / or improve the aroma or flavour perception by the user.

[0029] In some embodiments, the at least one first electrode comprises a plurality of first electrodes, optionally two or three, and the at least one second electrode comprises a plurality of second electrodes, optionally two or three. Optionally, the first electrodes and the second electrodes are arranged alternately such that each first electrode is sided by at least one second electrode and vice-versa.

[0030] The inventor found that, due to this arrangement, electromagnetic waves generated by the alternate voltage generator through the at least one first electrode and the at least one second electrode create line of electrical field inside the coating layer and parallel to the coating layer and provides an effective heating.

[0031] In some embodiments, the first electrodes and the second electrodes are arranged all in a common plane. The common plane may be close and parallel to the lying plane of the continuous sheet. The plurality of first electrodes and the plurality of second electrodes may be all disposed in a common plane parallel to the continuous sheet.

[0032] In some embodiments, the apparatus comprises groups of electrodes, each group of electrodes comprising the at least one first electrode and the at least one second electrode, the groups of electrodes being positioned at different locations along the conveying path.

[0033] The inventor found that the groups of electrodes may be placed to heat up the continuous sheet more than once along the conveying path.

[0034] The at least one first electrode and the at least one second electrode may have an elongated shape, optionally rod-shaped. For instance, a length of the at least one first electrode and / or of the at least one second electrode is from 5 cm to 30 cm, optionally from 10 cm to 20 cm. For instance, a diameter of the at least one first electrode and / or of the at least one second electrode is from 1 cm to 2 cm. For instance, a distance between the at least one first electrode and an adjacent at least one second electrode is from 1.5 cm to 10 cm, optionally from 2 cm to 4 cm. For instance, a distance of the at least one first electrode and at least one second electrode from the lying plane, measured perpendicularly to the lying plane, is from 0.5 cm to 3.0 cm.

[0035] Optionally, each of the at least one first electrode and the second electrode is oriented perpendicular to the conveying direction. In some embodiments, the at least one first electrode and the at least one second electrode are arranged parallel to each other.

[0036] The inventor found that this arrangement of the first electrode and second electrode allows to localize the oscillating electrical field in the metal layer and coating layer.

[0037] The at least one first electrode and the at least one second electrode may be arranged across a width of the continuous sheet, optionally across an entire width of the continuous sheet.

[0038] In some embodiments, the at least one first electrode and the at least one second electrode face the coating layer.

[0039] In some embodiments, the electromagnetic waves generated by the alternate voltage generator through the at least one first electrode and the at least one second electrode are reflected by the metal coating. The electromagnetic waves and the reflection by the metal coating may create standing waves of the oscillating electrical field.

[0040] The inventor found that the reflection by the metal coating and the standing waves provide a consistency induction heating, limiting discrepancy in the heating result.

[0041] In some embodiments, the induction heating unit comprises a casing having magnetic shielding capability, optionally a Faraday cage, and delimiting an inner chamber. The lying plane of the continuous sheet, the at least one first electrode and at least one second electrode may be placed in said inner chamber.

[0042] The inventor found that this arrangement allows to provide a protection versus the electromagnetic waves generated by the electrodes.

[0043] In some embodiments, a buffer unit is positioned downstream of the feeder. The buffer unit may comprise a plurality of rollers defining a zig-zag path for the continuous sheet, the zig-zag path having straight sections joined by curved sections. The at least one first electrode and the at least one second electrode may be side by side with at least one of the straight sections. Each group of electrodes may be coupled to a respective straight section.

[0044] In some embodiments, the plurality of rollers comprises a first group of rollers mounted on a first frame and a second group of rollers mounted on a second frame. The first frame and the second frame may be movable relative to each other to increase or decrease a length of the zig-zag path and of the continuous sheet in the buffer unit.

[0045] The inventor found that the position of the group of electrodes in the buffer unit is such that the distance of the electrodes from the continuous sheet does not change significantly even when the first frame and the second frame move relative to each other. In some embodiments, the heating unit further comprises a heating oven arranged downstream of the induction heating unit. The conveying path of the continuous sheet may cross the heating oven and being heated in the heating oven.

[0046] In some embodiments, the heating unit further comprises a heater roller arranged downstream of the induction heating unit. The continuous sheet may roll on said heater roller and may be heated by the heater roller.

[0047] The inventor found that the heated roller further heats the coating layer by contact once that the transition of the flavor to the amorphous state has happened and thus deposition of solid particles of aroma or flavor on the heater roller is prevented.

[0048] In some embodiments, the feeder comprises at least one reel holder supporting a respective bobbin of the continuous sheet. The feeder may comprise two reel holders each supporting a respective bobbin of the continuous sheet.

[0049] A splicing unit may be arranged downstream of the two reel holders and upstream of the buffer unit and may be configured to splice a head of the continuous sheet of a new bobbin when the continuous sheet of an old bobbin is running low.

[0050] The alternate voltage generator may be configured to generate an alternating voltage having a frequency between 5 KHz and 1 MHz, optionally between 200 KHz and 500 KHz. The alternate voltage generator may be configured to generate an alternating voltage having a maximum voltage between 30 V and 50 V. A frequency of the alternating voltage may be between 5 KHz and 1 MHz, optionally between 200 KHz and 500 KHz. A maximum voltage of the alternating voltage may be between 30 V to 50 V.

[0051] The oscillating electrical field may be generated only on the one side of the continuous sheet where the at least one first electrode and the at least one second electrode are located. The oscillating electrical field may be parallel or substantially parallel to the lying plane.

[0052] In some embodiments, at least one temperature sensor is arranged and configured to detect a temperature of the continuous sheet at the heating unit. A control unit may be operatively connected to the at least one sensor and to the induction heating unit. The control unit may be configured to control the alternate voltage generator as a function of the temperature detected by the at least one temperature sensor. The control unit may be configured to control the alternate voltage generator to generate standing waves of the oscillating electrical field. Particularly, a frequency of the alternating voltage is controlled such as to generate the standing waves.

[0053] The continuous sheet further may comprise a paper layer. The metal layer may be sandwiched between the paper layer and the coating layer. The inventor found that, if the at least one first electrode and the at least one second electrode face the coating layer and the metal layer is sandwiched between the paper layer and the coating layer, said at least one first electrode and the at least one second electrode face a side of the continuous sheet opposite the metal layer and the coating layer is interposed between the electrodes and the metal layer. This way, the oscillating electrical field is localized where the continuous sheet is to be heated (i.e. the coating layer).

[0054] The metal layer may be aluminum or a substrate that contain dipolar molecules . The coating layer may be menthol or a substrate that contain dipolar molecules.

[0055] A width of the continuous sheet may be from 10 cm to 20 cm. A thickness of the metal layer may be from 0.01 mm to 0.03 mm. A thickness of the coating layer may be from 0.01 mm to 0.03 mm. A thickness of the paper layer may be from 0.6 mm to 0.8 mm.

[0056] In some embodiments, heating the continuous sheet comprises: bringing the coating layer to a temperature configured to cause transition of the coating layer to an amorphous state. Heating the continuous sheet may comprise: bringing the coating layer to a temperature of at least 50 °C, optionally at least 55 °C, optionally between 55 °C and 65 °C.

[0057] A conveying speed of the continuous sheet along the conveying path may be between 2 m / s to 3 m / s.

[0058] In some embodiments, the apparatus for packaging aerosol-generating or smoking articles comprises an aerosol-generating or smoking articles feeding unit configured to feed aerosol-generating or smoking articles and a grouping unit configured for forming groups of aerosol-generating or smoking articles.

[0059] The apparatus for packaging aerosol-generating or smoking articles may further comprise a first packing unit positioned downstream of the embossing and punching unit and configured to enclose each group of aerosol-generating or smoking articles in a respective inner liner.

[0060] The apparatus for packaging aerosol-generating or smoking articles may further comprise a second packing unit positioned downstream of the first packing unit and configured to enclose in an outer package each group of aerosol-generating or smoking articles enclosed in the respective inner liner.

[0061] In some embodiments, the method for packaging aerosol-generating or smoking articles comprises: forming groups of aerosol-generating or smoking articles.

[0062] The method for packaging aerosol-generating or smoking articles may further comprise: enclosing each group of aerosol-generating or smoking articles in one respective inner liner. The method for packaging aerosol-generating or smoking articles may further comprise: enclosing each group of aerosol-generating or smoking articles wrapped in the inner-liner in an outer package.

[0063] In some embodiments, each group of aerosol-generating or smoking articles is enclosed in the inner liner by placing the coating layer in contact with the aerosol-generating or smoking articles.

[0064] As used in the present description, the term “continuous sheet” means a sheet of material having a main longitudinal dimension hundreds or thousands of times higher than a width of the sheet of material and the width that is hundreds of times or thousands of times higher than a thickness of the sheet of material.

[0065] As used in the present description, the terms “upstream” and “downstream” are referred to the conveying direction of the continuous sheet, i.e. the direction the continuous sheet travels, wherein said conveying direction is aligned with the main longitudinal dimension of said continuous sheet.

[0066] The invention is defined in the claims. However, below there is provided a non- exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0067] EX1. An apparatus for producing inner liners for packets of aerosol-generating or smoking articles, the apparatus comprising: a feeder of a continuous sheet, the continuous sheet comprising at least a metal layer and a coating layer comprising a flavor; a heating unit positioned downstream of the feeder, with respect to a conveying direction of the continuous sheet, and along a conveying path, the heating unit being configured to heat the continuous sheet to stabilize the coating layer on the continuous sheet; an embossing and punching unit positioned downstream of the heating unit and configured to emboss and punch the continuous sheet to form individual inner liners; wherein the heating unit comprises an induction heating unit comprising: an alternate voltage generator; at least one first electrode connected to a first terminal of the alternate voltage generator; at least one second electrode connected to a second terminal of the alternate voltage generator; wherein the at least one first electrode and the at least one second electrode are arranged side by side; wherein the at least one first electrode and the at least one second electrode are all arranged on one side of a lying plane of the continuous sheet traveling along the conveying path.

[0068] EX2. The apparatus according to EX1 , wherein the at least one first electrode comprises a plurality of first electrodes, optionally two or three, and the at least one second electrode comprises a plurality of second electrodes, optionally two or three.

[0069] EX3. The apparatus according to EX2, wherein the first electrodes and the second electrodes are arranged alternately such that each first electrode is sided by at least one second electrode and vice-versa.

[0070] EX4. The apparatus according to EX3, wherein the first electrodes and the second electrodes are arranged all in a common plane.

[0071] EX5. The apparatus according to EX4, wherein the common plane is close and parallel to the lying plane of the continuous sheet.

[0072] EX6. The apparatus according to any of EX1 to EX5, comprising groups of electrodes, each group of electrodes comprising the at least one first electrode and the at least one second electrode, the groups of electrodes being positioned at different locations along the conveying path.

[0073] EX7. The apparatus according to any of EX1 to EX6, wherein the at least one first electrode and the at least one second electrode have an elongated shape, optionally rodshaped.

[0074] EX8. The apparatus according to EX7, wherein each of the at least one first electrode and the second electrode is oriented perpendicular to the conveying direction.

[0075] EX9. The apparatus according to EX8, wherein the at least one first electrode and the at least one second electrode are arranged across a width of the continuous sheet, optionally across an entire width of the continuous sheet.

[0076] EX10. The apparatus according to any of EX7 to EX9, wherein the at least one first electrode and the at least one second electrode are arranged parallel to each other.

[0077] EX11. The apparatus according to any of EX1 to EX10, wherein a length of the at least one first electrode and the at least one second electrode is from 5 cm to 30 cm, optionally from 10 cm to 20 cm and / or a diameter of the at least one first electrode and the at least one second electrode is from 1 cm to 2 cm.

[0078] EX12. The apparatus according to any of EX1 to EX11 , wherein a distance between the at least one first electrode and an adjacent at least one second electrode is from 1 .5 cm to 10 cm, optionally from 2 cm to 4 cm.

[0079] EX13. The apparatus according to any of EX1 to EX10, wherein a distance of the at least one first electrode and at least one second electrode from the continuous sheet, measured perpendicularly to the lying plane, is from 0.5 cm to 3.0 cm. EX14. The apparatus according to any of EX1 to E13, wherein the induction heating unit comprises a casing having magnetic shielding capability, optionally a Faraday cage, and delimiting an inner chamber.

[0080] EX15. The apparatus according to EX14, wherein the lying plane of the continuous sheet, the at least one first electrode and at least one second electrode are placed in said inner chamber.

[0081] EX16. The apparatus according to any of EX1 to E15, comprising a buffer unit positioned downstream of the feeder.

[0082] EX17. The apparatus according to EX16, wherein the buffer unit comprises a plurality of rollers defining a zig-zag path for the continuous sheet, the zig-zag path having straight sections joined by curved sections.

[0083] EX18. The apparatus according to EX17, wherein the at least one first electrode and the at least one second electrode are side by side with at least one of the straight sections.

[0084] EX19. The apparatus according to EX18 when EX16 is according to EX6, wherein each group of electrodes is coupled to a respective straight section.

[0085] EX20. The apparatus according to any of EX17 to EX19, wherein the plurality of rollers comprises a first group of rollers mounted on a first frame and a second group of rollers mounted on a second frame, the first frame and the second frame being movable relative to each other to increase or decrease a length of the zig-zag path and of the continuous sheet in the buffer unit.

[0086] EX21. The apparatus according to any of EX1 to EX20, wherein the heating unit further comprises a heating oven arranged downstream of the induction heating unit, the conveying path of the continuous sheet crossing the heating oven and being heated in the heating oven.

[0087] EX22. The apparatus according to any of EX1 to EX21 , wherein the heating unit further comprises a heater roller arranged downstream of the induction heating unit, the continuous sheet rolling on said heater roller and being heated by the heater roller.

[0088] EX23. The apparatus according to any of EX1 to E22, wherein the feeder comprises at least one reel holder supporting a respective bobbin of the continuous sheet.

[0089] EX24. The apparatus according to EX23, wherein the feeder comprises two reel holders each supporting a respective bobbin of the continuous sheet.

[0090] EX25. The apparatus according to EX24, further comprising a splicing unit arranged downstream of the two reel holders and upstream of the buffer unit and configured to splice a head of the continuous sheet of a new bobbin when the continuous sheet of an old bobbin is running low. EX26. The apparatus according to any of EX1 to EX25, wherein the alternate voltage generator is configured to generate an alternating voltage having a frequency between 5 KHz and 1 MHz, optionally between 200 KHz and 500 KHz.

[0091] EX27. The apparatus according to any of EX1 to EX26, wherein the alternate voltage generator is configured to generate an alternating voltage having a maximum voltage between 30 V and 50 V.

[0092] EX28. The apparatus according to any of EX1 to EX27, comprising at least one temperature sensor arranged and configured to detect a temperature of the continuous sheet at the heating unit and a control unit operatively connected to the at least one sensor and to the induction heating unit; the control unit being configured to control the alternate voltage generator as a function of the temperature detected by the at least one temperature sensor; optionally the control unit is configured to control the alternate voltage generator to generate standing waves of the oscillating electrical field; optionally a frequency of the alternating voltage is controlled such as to generate the standing waves.

[0093] EX29. The apparatus according to any of EX1 to EX28, wherein the apparatus is configured to work the continuous sheet comprising the at least a metal layer and the coating layer comprising the flavor.

[0094] EX30. The apparatus according to EX29, wherein the continuous sheet further comprises a paper layer and the metal layer is sandwiched between the paper layer and the coating layer.

[0095] EX31 . The apparatus according to EX30, wherein the at least one first electrode and the at least one second electrode face the coating layer.

[0096] EX32. An apparatus for packaging aerosol-generating or smoking articles, comprising the apparatus for producing inner liners according to any of EX1 to EX31.

[0097] EX33. The apparatus according to EX32, further comprising: an aerosol-generating or smoking articles feeding unit configured to feed aerosolgenerating or smoking articles and a grouping unit configured for forming groups of aerosolgenerating or smoking articles; a first packing unit positioned downstream of the embossing and punching unit and configured to enclose each group of aerosol-generating or smoking articles in a respective inner liner; a second packing unit positioned downstream of the first packing unit and configured to enclose in an outer package each group of aerosol-generating or smoking articles enclosed in the respective inner liner. EX34. A method for producing inner liners for packets of aerosol-generating or smoking articles, the method being carried out through the apparatus according to any of EX1 to EX33.

[0098] EX35. A method for producing inner liners for packets of aerosol-generating or smoking articles, the method comprising:

[0099] - feeding a continuous sheet comprising a metal layer and a coating layer comprising a flavor along a conveying path and in a conveying direction; heating the continuous sheet to stabilize the coating layer on the continuous sheet; embossing and punching the continuous sheet to form individual inner liners; wherein heating the continuous sheet comprises: moving the continuous sheet close to at least one first electrode and at least one second electrode all arranged on one side of the continuous sheet traveling along the conveying path; wherein the at least one first electrodes is connected to a first terminal of an alternate voltage generator and the at least one second electrode are connected to a second terminal of the alternate voltage generator, wherein the at least one first electrode and the at least one second electrode are arranged side by side; applying an alternating voltage to the at least one first electrode and the at least one second electrode through the alternate voltage generator to generate an oscillating electrical field inducing currents in the metal layer and heating the metal layer by Joule effect, wherein the generated heat heats up the coating layer.

[0100] EX36. The method according to EX35, the method being carried out through the apparatus according to any of EX1 to EX31.

[0101] EX37. The method according to EX35 or EX36, wherein the at least one first electrode comprises a plurality of first electrodes and the at least one second electrode comprises a plurality of second electrodes.

[0102] EX38. The method according to EX37, wherein the first electrodes and the second electrodes are arranged alternately such that each first electrode is sided by at least one second electrode and vice-versa.

[0103] EX39. The method according to EX37 or EX38, wherein the plurality of first electrodes and the plurality of second electrodes are all disposed in a common plane parallel to the continuous sheet.

[0104] EX40. The method according to any of EX35 to EX39, wherein the oscillating electrical field is generated only on the one side of the continuous sheet where the at least one first electrode and the at least one second electrode are located and / or the oscillating electrical field is parallel or substantially parallel to the lying plane. EX41 . The method according to any of EX35 to EX40, wherein the continuous sheet further comprises a paper layer and the metal layer is sandwiched between the paper layer and the coating layer.

[0105] EX42. The method according to any of EX35 to EX41 , wherein the at least one first electrode and the at least one second electrode face the coating layer.

[0106] EX43. The method according to any of EX35 to EX42, wherein a distance of the at least one first electrode and at least one second electrode from the lying plane, measured perpendicularly to the lying plane, is from 0.5 cm to 3.0 cm.

[0107] EX44. The method according to any of EX35 to EX43, wherein a frequency of the alternating voltage is between 5 KHz and 1 MHz, optionally between 200 KHz and 500 KHz.

[0108] EX45. The method according to any of EX35 to EX44, wherein a maximum voltage of the alternating voltage is between 30 V to 50 V.

[0109] EX46. The method according to any of EX35 to EX45, wherein a length of the at least one first electrode and the at least one second electrode is from 5 cm to 30 cm, optionally from 10 cm to 20 cm and / or a diameter of the at least one first electrode and the at least one second electrode is from 1 cm to 2 cm.

[0110] EX47. The method according to any of EX35 to EX46, wherein a distance between the at least one first electrode and an adjacent at least one second electrode is from 1 .5 cm to 10 cm, optionally from 2 cm to 4 cm.

[0111] EX48. The method according to any of EX35 to EX47, wherein heating the continuous sheet comprises: bringing the coating layer to a temperature configured to cause transition of the coating layer to an amorphous state.

[0112] EX49. The method according to any of EX35 to EX48, wherein heating the continuous sheet comprises: bringing the coating layer to a temperature of at least 50 °C, optionally at least 55 °C, optionally between 55 °C and 65 °C.

[0113] EX50. The method according to any of EX35 to EX49, wherein the metal layer is aluminum or a substrate that contain dipolar molecules .

[0114] EX51 . The method according to any of EX35 to EX50, wherein the coating layer is menthol or a substrate that contain dipolar molecules.

[0115] EX52. The method according to any of EX35 to EX51 , wherein a width of the continuous sheet is from 10 cm to 20 cm.

[0116] EX53. The method according to any of EX35 to EX52, wherein a thickness of the metal layer is from 0.01 mm to 0.03 mm.

[0117] EX54. The method according to any of EX35 to EX53, wherein a thickness of the coating layer is from 0.01 mm to 0.03 mm. EX55. The method according to EX41 or to any of EX42 to EX54 when according to EX41 , wherein a thickness of the paper layer is from 0.6 mm to 0.8 mm.

[0118] EX56. The method according to any of EX35 to EX55, wherein a conveying speed of the continuous sheet along the conveying path is between 2 m / s to 3 m / s.

[0119] EX57. The method according to any of EX35 to EX56, wherein the electromagnetic waves generated by the alternate voltage generator through the at least one first electrode and the at least one second electrode are reflected by the metal coating; optionally wherein the electromagnetic waves and the reflection by the metal coating create standing waves of the oscillating electrical field.

[0120] EX58. A method for packaging aerosol-generating or smoking articles, comprising the method for producing inner liners according to any of EX35 to EX56.

[0121] EX59. The method according to EX58, further comprising:

[0122] - forming groups of aerosol-generating or smoking articles; enclosing each group of aerosol-generating or smoking articles in one respective inner liner; enclosing each group of aerosol-generating or smoking articles wrapped in the inner-liner in an outer package.

[0123] EX60. The method according to EX59, wherein each group of aerosol-generating or smoking articles is enclosed in the inner liner by placing the coating layer in contact with the aerosol-generating or smoking articles.

[0124] EX61. A packet of aerosol-generating or smoking articles made through the apparatus according to EX32 or EX33 or through the method according to EX58 or EX60.

[0125] EX62. The packet according to EX61 , wherein the aerosol-generating or smoking articles are heat-not-burn cigarettes (RRP - Reduced Risk Product).

[0126] EX63. The packet according to EX61 , wherein the aerosol-generating or smoking articles are conventional burning articles.

[0127] Examples will now be further described with reference to the figures in which:

[0128] Figure 1 shows an apparatus for packaging aerosol-generating or smoking articles;

[0129] Figure 2 is a packet of aerosol-generating or smoking articles manufactured through the apparatus of figure 1 ;

[0130] Figure 3 shows a portion of apparatus of figure 1 ;

[0131] Figure 4 is a section view of a continuous sheet processed in the apparatus of figure 1 ;

[0132] Figure 5 is a heating unit part of the apparatus of figure 1 ;

[0133] Figure 6 shows elements of the heating unit of figure 5

[0134] Figure 7 is an enlarged portion of the portion of figure 3; Figure 8 is the section view of figure 4 showing standing waves of an oscillating electrical field generated by the heating unit of figure 5.

[0135] The apparatus 1 shown in Figure 1 is configured for packaging aerosol-generating or smoking articles, such as heat-not-burn cigarettes (RRP - Reduced Risk Product) or conventional burning articles. Particularly, the apparatus 1 is configured to making packets 2, each containing a group of aerosol-generating or smoking articles, and for making cartons each containing groups of packets 2. One packet 2 is shown in figure 2 and comprises an outer package 3 with a lid 4 and an inner liner 5. Each group of aerosolgenerating or smoking articles, not shown, is wrapped in the inner liner 5 and inserted in the outer package 3.

[0136] The apparatus 1 for packaging aerosol-generating or smoking articles comprises an apparatus 6 for producing the inner liners 5 positioned upstream of a first packing unit 7 a second packing unit 8.

[0137] The apparatus 6 for producing the inner liners 5 comprises an inner liner unwinding unit 9 followed by an embossing and punching unit 10.

[0138] The inner liner unwinding unit 9 comprises (figure 3) two reel holders 11 , 1 T each supporting a respective bobbin 12, 12’ of a continuous sheet 13, 13’. In the example embodiment, a first upper reel holder 11 and bobbin 12 and a second lower reel holder 1 T and bobbin 12’ are disclosed. The two reel holders 11 , 1 T compose a feeder of continuous sheets 13, 13’ previously manufactured by depositing a coating layer 15 on a laminated paper sheet.

[0139] The continuous sheets 13, 13’ of the two reel holders 11 , 1 T have the same features. Therefore, only the continuous sheets 13 of the first upper reel holder 11 and bobbin 12 will be detailed.

[0140] The continuous sheets 13 comprises a metal layer 14, usually of aluminum, the coating layer 15 comprising a flavor, usually menthol, and a paper layer 16. As shown in figure 4, the metal layer 14 is sandwiched between the coating layer 15 and the paper layer 16. A width of the continuous sheet 13 is for instance from 10 cm to 20 cm. A thickness of the metal layer 14 is for instance from 0.01 mm to 0.03 mm. A thickness of the coating layer 15 is for instance from 0.01 mm to 0.03 mm. A thickness of the paper layer 16 is for instance from 0.6 mm to 0.8 mm.

[0141] A splicing unit 17 is arranged downstream of the two reel holders 11 , 1 T and is configured to splice a head of the continuous sheet 13, 13’ of a new bobbin (for instance the bobbin 12 of the first upper reel holder 11) when the continuous sheet of an old bobbin (for instance the bobbin 12 of the first upper reel holder 11) is running low (for instance the bobbin 12’ of the second lower reel holder 1 T). The structure of the splicing unit 17 may be per se known and is not here described in detail.

[0142] A buffer unit 18 is positioned downstream of the splicing unit 17. The structure and the function of the buffer unit 18 may be per se known. The buffer unit 18 comprises a first group of rollers 19 mounted on a first frame, not shown, and a second group of rollers 20 mounted on a second frame embodied as a swing arm 21. The rollers 19, 20 guide the continuous sheet along a zig-zag path having straight sections joined by curved sections and the swiveling of the swing arm 21 changes a length of the zig-zag path. The buffer unit 18 allows to change bobbins without stopping the feeding of continuous sheet 13, 13’ to the first packing unit 7. Indeed, when the splicing occurs and so the incoming of continuous sheet 13, 13’ is slowed down, the swing arm 21 rotates so that the second group of rollers 20 gets closer to the a first group of rollers 19 to provide an extra length of continuous sheet 13, 13’ to the downstream process, balancing the slowing down of the upstream bobbins 12, 12’.

[0143] The disclosed embodiment of the inner liner unwinding unit 9 further comprises an oven 22 arranged downstream of the buffer unit 18 and delimiting an inner chamber crossed by the conveying path of the continuous sheet 13, 13’ and a heater roller 23 arranged downstream of the oven 22. In the oven, the continuous sheet 13, 13’ contacts heated surfaces, not shown, and is heated by conduction and radiation. The continuous sheet 13, 13’ is also in contact with a lateral the heated roller 23 and is heated by conduction and radiation.

[0144] The inner liner unwinding unit 9 further comprises an induction heating unit 24. The induction heating unit 24 together with the oven 22 and the heated roller 23 form a heating unit of the apparatus 6 for producing inner liners 5 for packets of aerosol-generating or smoking articles.

[0145] The induction heating unit 24 is provided with an alternate voltage (AC) generator 25 operatively connected to a plurality of first electrodes 26 connected to a first terminal 27 of the alternate voltage generator 25 and a plurality of second electrodes 28 connected to a second terminal 29 of the alternate voltage generator 25 (figures 5 and 6).

[0146] The induction heating unit 24 is placed along the conveying path and between the splicing unit 17 and the oven 22.

[0147] In the embodiment of figures 5 and 6, the induction heating unit 24 is placed side by side to the continuous sheet 13 along a straight part of the conveying path. Each first electrode 26 and each second electrode 28 have an elongated rod-shape with circular cross section. The plurality of first electrodes 26 and the plurality of second electrodes 28 are all disposed in a common plane parallel to the continuous sheet traveling along the conveying path and in a conveying direction “C” and all on a side of the continuous sheet 13 provided with the coating layer 15. Therefore, the first electrodes 26 and the second electrodes 28 face said coating layer 15. The common plane is tangent to the lateral surfaces of the rodshaped first electrodes 26 and second electrodes 28 (figure 5).

[0148] The first electrodes 26 and the second electrodes 28 are arranged alternately along the conveying direction “C”, such that each first electrode 26 is sided by one second electrode 28 and vice-versa. The common plane is close and parallel to a lying plane of the continuous sheet 13. For instance, a distance of the first electrodes and second electrodes from the continuous sheet, measured perpendicularly to the lying plane, is from 0.5 cm to 3.0 cm.

[0149] In the embodiment illustrated in figures 5 and 6, the first electrodes 26 and the second electrodes 28 are oriented perpendicular to the conveying direction “C” and a length of each first electrode 26 and second electrode 28 is equal to or greater than the width of the continuous sheet 13, such that each electrodes 26, 28 extends across the entire width of the continuous sheet 13.

[0150] For instance, a length of each first electrode 26 and second electrode 28 is from 10 cm to 20 cm and a diameter of each first electrode 26 and second electrode 28 is from 1 cm to 2 cm, a distance between a first electrode 26 and an adjacent second electrode 28 is from 2 cm to 4 cm.

[0151] In the embodiment of figure 7, the induction heating unit 24 comprises groups of electrodes. Each group of electrodes comprises one first electrode 26 and one second electrode 28. The groups of electrodes are positioned at different locations along the straight sections of the zig-zag path of the buffer unit 18. Each group is positioned between two straight portions.

[0152] The apparatus 6 for producing inner liners 5 for packets of aerosol-generating or smoking articles further comprises one or more temperature sensor / s 30 arranged and configured to detect a temperature of the continuous sheet 13 moving through the induction heating unit 24 or just downstream of the induction heating unit 24. A control unit 31 is operatively connected to the sensor / s 30 and to the induction heating unit 24. The control unit 31 is configured to control the alternate voltage generator 25 as a function of the temperature detected by the temperature sensor / s 30.

[0153] The control unit 31 is configured to control the alternate voltage generator 25 to generate an alternating voltage having a frequency between 5 KHz and 1 MHz, preferably between 200 KHz and 500 KHz, with a maximum voltage between 30 V and 50 V. Thus, an alternating voltage is applied to the first electrodes 26 and to the second electrodes 28 which generates an oscillating electrical field “E” which, in turn, induces currents in the metal layer 14 that heats up by Joule effect. The generated heat heats up the coating layer 15 while the continuous sheet 13 travels in the conveying direction “C” with a conveying speed between 2 m / s to 3 m / s. The coating layer 15 is brought to a temperature between 55 °C and 65 °C configured to cause transition of the coating layer to an amorphous state, which makes the flavor more stable on the continuous sheet 13.

[0154] Therefore, when the continuous sheet 13 travels in contact with the heated surfaces of the oven 22 and on the heated roller 23 and also on other elements of the apparatus 1 for packaging aerosol-generating or smoking articles placed downstream, deposition of solid particles of flavour is decreased or prevented.

[0155] The oscillating electrical field “E” is generated only on the side of the continuous sheet 13 where the first electrodes 26 and the second electrodes 28 are located. The oscillating electrical field “E” is parallel or substantially parallel to the lying plane of the continuous sheet 13 and located inside the metal layer 14 and the coating layer 15.

[0156] Since the coating layer 15 is interposed between the electrodes 26, 28 and the metal layer 14, the metal layer reflects the electromagnetic waves. The control unit 31 may be configured to control the alternate voltage generator 25 to generate standing waves “W’ of the oscillating electrical field (figure 8). In particular, the frequency of the alternating voltage is controlled such as to generate the standing waves. Indeed, the condition to have a standing wave is to have the following relation between the frequency and the distance “D” between the electrodes 26, 28 and the metal layer 14 of the continuous sheet 13:

[0157] F = nc / 2D for n = 0, 1 , ... wherein “c” is the speed of the wave.

[0158] In variant embodiments, not shown in drawings, the induction heating unit 24 of figure 5 is located inside the oven 22 of figure 3 in place of the heated surfaces. A casing 32 of the oven 22 has magnetic shielding capability, like a Faraday cage, and delimits an inner chamber housing the first electrodes 26 and the second electrodes 28.

[0159] The continuous sheet 13 with the stabilized coating layer 15 moves through the embossing and punching unit 10 where the continuous sheet 13 is embossed to create weakened lines along which said continuous sheet 13 can be more easily folded. In the embossing and punching unit 10 individual inner liners 5 provided with weakened lines are also cut out.

[0160] The individual inner liners 5 are carried to the first packing unit 7 where groups of aerosol-generating or smoking articles are each enclosed in respective inner liners 5. The first packing unit 7 is operatively coupled to a feeding unit 33 and to a grouping unit 34, which may be both per se known.

[0161] The feeding unit 33 feeds a flow 35 of aerosol-generating or smoking articles to the grouping unit 36 which parts the flow in a plurality of individual groups 36 of aerosol- generating or smoking articles. Each group 36 is transferred to the first packing unit 7 where it is enclosed in one inner liner 5 by placing the coating layer 15 in contact with the aerosolgenerating or smoking articles (the metal layer 14 facing outside).

[0162] Downstream of the first packing unit 7, in the second packing unit 8, each group 36 enclosed in the inner liner 5 is enclosed in the outer package 3 to form the packet 2 of figure 2. Then, in a sealing station 37, each packet 2 is cellophaned. Finally, in further packing unit 38, the packets 2 are grouped and packed in cartons.

[0163] The apparatus 6 for producing inner liners for packets of aerosol-generating or smoking articles above described is therefore configured to carry out a method for producing inner liners for packets of aerosol-generating or smoking articles. The apparatus 1 for packaging aerosol-generating or smoking articles above described is therefore configured to carry out a method for packaging aerosol-generating or smoking articles.

Claims

CLAIMS1. An apparatus for producing inner liners for packets of aerosol-generating articles or smoking articles, the apparatus comprising: a feeder of a continuous sheet (13, 13’), the continuous sheet (13, 13’) comprising at least a metal layer (14) and a coating layer (15) comprising a flavor; a heating unit (22, 23, 24) positioned downstream of the feeder (11 , 11’), with respect to a conveying direction (C) of the continuous sheet (13, 13’), and along a conveying path, the heating unit (22, 23, 24) being configured to heat the continuous sheet (13, 13’) to stabilize the coating layer (15) on the continuous sheet (13, 13’); an embossing and punching unit (10) positioned downstream of the heating unit (22, 23, 24) and configured to emboss and punch the continuous sheet (13, 13’) to form individual inner liners (5); wherein the heating unit (22, 23, 24) comprises an induction heating unit (24) comprising: an alternate voltage generator (25); at least one first electrode (26) connected to a first terminal (27) of the alternate voltage generator (25); at least one second electrode (28) connected to a second terminal (29) of the alternate voltage generator (25); wherein the at least one first electrode (26) and the at least one second electrode (28) are arranged side by side; wherein the first electrode (26) and the second electrode (28) are all arranged on one side of a lying plane of the continuous sheet (13, 13’) traveling along the conveying path; the induction heating unit (24) being configured to generate an oscillating electrical field (E) inducing currents in the metal layer (14) and heating the metal layer (14) by Joule effect, wherein the generated heat heats up the coating layer (15).

2. The apparatus according to claim 1 , wherein the at least one first electrode (26) comprises a plurality of first electrodes (26) and the at least one second electrode (28) comprises a plurality of second electrodes (28), wherein the first electrodes (26) and the second electrodes (28) are arranged alternately such that each first electrode (26) is sided by at least one second electrode (28) and vice-versa; wherein the first electrodes (26) and the second electrodes (28) are arranged all in a common plane (P); wherein the common plane (P) is close and parallel to the lying plane of the continuous sheet (13, 13’).

3. The apparatus according to claim 1 or 2, wherein each of the at least one first electrode (26) and the at least one second electrode (28) has an elongated shape oriented perpendicular to the conveying direction (C) and the at least one first electrode (26) and the at least one second electrode (28) are arranged across a width of the continuous sheet (13, 13’).

4. The apparatus according to any of claims 1 to 3, wherein a length of each the at least one first electrode (26) and the at least one second electrode (28) is from 5 cm to 30 cm, wherein a distance between the at least one first electrode (26) and an adjacent at least one second electrode (28) is from 1.5 cm to 10 cm, wherein a distance of the at least one first electrode (26) and at least one second electrode (28) from the lying plane, measured perpendicularly to the lying plane, is from 0.5 cm to 3.0 cm.

5. The apparatus according to any of claims 1 to 4, wherein the induction heating unit (24) comprises a casing having magnetic shielding capability and delimiting an inner chamber, wherein the lying plane of the continuous sheet (13, 13’), the at least one first electrode (26) and at least one second electrode (28) are placed in said inner chamber.

6. The apparatus according to any of claims 1 to 5, comprising a buffer unit (18) positioned downstream of the feeder (11 , 11’), the buffer unit (18) comprising a plurality of rollers (19, 20) defining a zig-zag path for the continuous sheet (13, 13’), the zig-zag path having straight sections joined by curved sections; wherein the at least one first electrode (26) and the at least one second electrode (28) are side by side with at least one of the straight sections.

7. Apparatus for packaging aerosol-generating or smoking articles, comprising: the apparatus for producing inner liners according to any of claims 1 to 6; an aerosol-generating or smoking articles feeding unit (33) configured to feed aerosol-generating or smoking articles and a grouping unit (34) configured for forming groups (36) of aerosol-generating or smoking articles; a first packing unit (7) positioned downstream of the embossing and punching unit (10) and configured to enclose each group (36) of aerosol-generating or smoking articles in a respective inner liner (5);a second packing unit (8) positioned downstream of the first packing unit (7) and configured to enclose in an outer package each group (36) of aerosol-generating or smoking articles enclosed in the respective inner liner (5).

8. Method for producing inner liners for packets of aerosol-generating or smoking articles, the method comprising: feeding a continuous sheet (13, 13’) comprising a metal layer (14) and a coating layer (15) comprising a flavor along a conveying path and in a conveying direction (C); heating the continuous sheet (13, 13’) to stabilize the coating layer (15) on the continuous sheet (13, 13’); embossing and punching the continuous sheet (13, 13’) to form individual inner liners (5); wherein heating the continuous sheet (13, 13’) comprises: moving the continuous sheet close to at least one first electrode (26) and at least one second electrode (28) all arranged on one side of the continuous sheet (13, 13’) traveling along the conveying path (C); wherein the at least one first electrodes (26) is connected to a first terminal (27) of an alternate voltage generator (25) and the at least one second electrode are connected to a second terminal of the alternate voltage generator (25), wherein the at least one first electrode (26) and the at least one second electrode (28) are arranged side by side; applying an alternating voltage to the at least one first electrode (26) and the at least one second electrode (28) through the alternate voltage generator (25) to generate an oscillating electrical field (E) inducing currents in the metal layer (14) and heating the metal layer (14) by Joule effect, wherein the generated heat heats up the coating layer (15).

9. The method according to claim 8, wherein the at least one first electrode (26) comprises a plurality of first electrodes (26) and the at least one second electrode (28) comprises a plurality of second electrodes (28), wherein the first electrodes (26) and the second electrodes (28) are arranged alternately such that each first electrode (26) is sided by at least one second electrode (28) and vice-versa; wherein the plurality of first electrodes (26) and the plurality of second electrodes (28) are all disposed in a common plane parallel to the continuous sheet (13, 13’).

10. The method according to claim 8 or 9, wherein the continuous sheet (13, 13’) further comprises a paper layer (16) and the metal layer (14) is sandwiched between the paperlayer (16) and the coating layer (15), wherein the at least one first electrode (26) and the at least one second electrode (28) face the coating layer (15).

11. The method according to any of claims 8 to 10, wherein a distance of the at least one first electrode (26) and at least one second electrode (28) from the continuous sheet (13, 13’), measured perpendicularly to the continuous sheet (13, 13’), is from 0.5 cm to 3.0 cm.

12. The method according to any of claims 8 to 11 , wherein a frequency of the alternating voltage is between 5 KHz and 1 MHz; wherein a maximum voltage of the alternating voltage is between 30 V and 50 V.

13. The method according to any of claims 8 to 12, wherein heating the continuous sheet (13, 13’) comprises: bringing the coating layer (15) to a temperature of at least 50 °C.

14. The method according to any of claims 8 to 12, wherein the metal layer (14) is aluminum and the coating layer (15) is menthol.

15. Method for packaging aerosol-generating or smoking articles, comprising: the method for producing inner liners according to any of claims 8 to 14; forming groups (36) of aerosol-generating or smoking articles; enclosing each group (36) of aerosol-generating or smoking articles in one respective inner liner (5); enclosing each group (36) of aerosol-generating or smoking articles wrapped in the inner-liner (5) in an outer package (3).

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