Method and apparatus for applying a susceptor wire to an aerosol-forming substrate

Abstract

The present invention relates to a method for applying a susceptor wire (1) to an aerosol-forming substrate (9) for use in an inductively heatable aerosol-generating article, and specifically to an apparatus (5) for applying a susceptor wire (1) to an aerosol-forming substrate (9) in accordance with the method of the present invention. The method includes the steps of providing an aerosol-forming substrate (9) in the form of a sheet material (10), providing a plurality of susceptor wires (1) from a wire supply (6), and depositing the plurality of susceptor wires (1) on a major outer surface of the sheet material (10).

Description

[Technical Field]

[0001] The present disclosure relates to a method of applying a susceptor wire to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article, and to equipment for applying a susceptor wire for aerosol formation, particularly for use in a method according to the present disclosure. [Background technology]

[0002] Aerosol generating systems using induction heating to generate inhalable aerosols are generally known in the prior art. Such systems may comprise an induction heating aerosol generating device and a separate aerosol-generating article for use with the device. Among other components, the article may include an aerosol-forming substrate capable of forming an inhalable aerosol when heated, and an inductively heatable susceptor arrangement in thermal proximity or direct physical contact with the substrate to heat the substrate. Inductive heating of the susceptor arrangement is accomplished by its interaction with an alternating magnetic field provided by the aerosol generating device. During operation, the alternating magnetic field induces at least one of heat-generating eddy currents or hysteresis losses in the susceptor arrangement, causing the latter to heat to a temperature sufficient to release volatile compounds from the heated substrate, which can then be cooled to form an aerosol.

[0003] Depending on the type of substrate and the shape of the article, different configurations of susceptor element-susceptor arrangements are known. As an example, an article may include a single solid susceptor element, such as a susceptor strip, embedded in a solid or gel-like aerosol-forming substrate within the article's substrate portion. While solid susceptor elements are low cost and readily available, they create a single central heat source that can result in uneven temperature distribution across the substrate portion. This is because direct heating of the substrate occurs only in the immediate vicinity of the susceptor element, while the peripheral region of the substrate portion is heated only indirectly by heat conduction across adjacent substrate layers. Specifically, high temperature gradients can overheat the interior region of the substrate portion near the susceptor element, while the temperature in the peripheral region of the substrate portion may be too low to volatilize the substrate. Furthermore, the heating efficiency of this configuration is highly sensitive to the proper positioning of the susceptor element within the substrate. All of this can lead to suboptimal utilization of the aerosol-forming substrate. Alternatively, articles have been proposed that include spherical or quasi-spherical susceptor particles that are uniformly hindered throughout the aerosol-forming substrate. While leading to more uniform heating of the substrate, the heating efficiency of this susceptor configuration is limited, which can also affect extraction efficiency.

[0004] It would therefore be desirable to have an aerosol-forming substrate that possesses the advantages of the prior art while mitigating their limitations. In particular, it would be desirable to have a method of applying a susceptor wire to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article such that the aerosol-forming substrate may provide more efficient heating and utilization of the aerosol-forming substrate. Summary of the Invention

[0005] According to one aspect of the present invention, a method for applying a susceptor wire to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article is disclosed.

[0006] The method includes the step of providing an aerosol-forming substrate in the form of a sheet material.

[0007] The method further includes providing a plurality of susceptor wires from a wire supply.

[0008] The method also includes depositing a plurality of susceptor wires on a major outer surface of the sheet material.

[0009] Generally, as used herein, the term "wire" refers to an elongated element having a greater extent in one major dimension, the length extension, than in two remaining dimensions perpendicular (transverse) to the major dimension. In other words, the length extension of a susceptor wire is greater than its width / height or diameter. Specifically, the term susceptor wire may refer to a susceptor element having a length dimension that is greater than any transverse dimension perpendicular to the length dimension. In particular, the susceptor wire may be a continuous susceptor wire. Consequently, as used herein, the term transverse dimension refers to the dimension perpendicular to the major dimension (length extension) of the susceptor wire.

[0010] Compared to a single solid susceptor element, the use of multiple susceptor wires dispersed throughout the aerosol-forming substrate in the final product, i.e., aerosol-generating article, advantageously results in a more uniform heat distribution across the substrate without any significant temperature gradients across different substrate regions. Furthermore, if the susceptor material of the susceptor wires has a high thermal conductivity, the uniformity of heat distribution is further enhanced by the fact that a substrate with multiple susceptor wires dispersed therein exhibits an equivalent increase in thermal conductivity compared to a substrate without susceptor elements or with only a single solid susceptor element. Furthermore, in achieving uniform heat distribution, the proposed susceptor arrangement is less sensitive to the positioning of the susceptor wire compared to a single solid susceptor element.

[0011] Most importantly, we found that the geometry, specifically the relative dimensions of the susceptor wire, has a significant impact on heating efficiency and, therefore, substrate extraction efficiency. In this regard, we found that susceptor wires (which have a finite length in the final product) are less prone to demagnetization effects than more uniformly sized susceptor elements, such as spherical or quasi-spherical susceptor particles. This can be explained as follows: When a susceptor wire (of finite length) is placed in an external magnetic field, it becomes progressively magnetized. As the external magnetic field increases, the internal magnetization also increases. This process continues until the magnetization reaches the magnetic saturation point of the material, beyond which no further magnetization can occur. As a result, the magnetization of the susceptor wire causes a buildup of magnetic charge density at both ends of the susceptor wire, as seen in the direction of the external magnetic field. As a result, the susceptor wire generates a magnetic field that causes self-interaction with the material. This magnetic field is directed in the same direction as the external magnetic field but opposite to it, and is therefore called the demagnetizing field. The demagnetizing field depends on the geometry of the susceptor wire but not on its absolute dimensions. If the susceptor wire responds to changes in the external magnetic field, the demagnetizing field is generally assumed to be proportional to the magnetization in each direction, related to a geometry-dependent proportionality constant known as the demagnetization factor. The demagnetization factor depends not only on the shape of the susceptor wire but also on its orientation relative to the external magnetic field. To this extent, it has been found that an external magnetic field extending through a susceptor wire with a length dimension significantly greater than any transverse dimension perpendicular to the length dimension generates a weaker, or even negligible, demagnetizing field compared to non-elongated (equally sized) susceptor elements, such as spherical or quasi-spherical susceptor elements. This is intuitive because, in a properly aligned susceptor wire, the magnetic charge densities accumulated at both ends of the susceptor wire are spatially spaced apart from each other. This causes the demagnetizing field to be significantly reduced in strength and therefore have less effect on the magnetizing field which causes power loss.As a result, power loss, and therefore heating efficiency, is greater for susceptor wires than for non-elongated (equidistant) susceptor elements, such as spherical or quasi-spherical susceptor elements. This is particularly true when the magnetic field orientation is substantially parallel to the length dimension of the susceptor wire, a configuration in which heating performance is maximized. Nevertheless, it has been found that the susceptor wire does not necessarily need to be aligned perfectly parallel to the external magnetic field direction. Even when the susceptor wire is aligned within a certain range of angles with respect to the external magnetic field orientation, the overall heating performance is still higher than for susceptor arrangements with randomly oriented susceptor wires.

[0012] As mentioned above, heating performance is maximized for a substantially parallel alignment. As a result, the susceptor wires are preferably aligned substantially parallel to one another. As used herein, the term "substantially parallel" is understood to mean "a deviation of ±5 degrees from a parallel arrangement."

[0013] In the present disclosure, whenever a number or range is given for a plurality of objects, such as a plurality of susceptor wires, this means that the number or range applies to at least 60 percent, specifically at least 70 percent, more specifically at least 80 percent, and particularly at least 90 percent of all objects of the plurality of objects, and preferably applies to all objects of the plurality of objects. For example, when the present disclosure states that the susceptor wires are aligned substantially parallel to one another, this means that at least 60 percent, specifically at least 70 percent, more specifically at least 80 percent, and particularly at least 90 percent of all susceptor wires are aligned substantially parallel.

[0014] Thus, the induction-heated aerosol-generating article may be provided with a more uniform heat distribution within the aerosol-forming substrate due to the presence of multiple susceptor wires distributed across the outer major surface of the sheet material, while at the same time the susceptor wires are optimally aligned with the alternating magnetic field provided by the aerosol-generating device, thus providing a higher heating efficiency compared to randomly oriented susceptor wires. Additionally, an optimal density of deposited susceptor wires per square area unit of the outer major surface of the sheet material may be provided depending on the desired heating efficiency.

[0015] In a preferred embodiment, the multiple susceptor wires may be continuous susceptor wires, each provided from a bobbin that is part of a wire supply. The multiple susceptor wires may be provided to the wire supply coiled on a single bobbin, or each susceptor wire may be coiled on its own bobbin. The susceptor wires may be cut to a desired length extension before or after being deposited on the major outer surface of the sheet material. Preferably, the susceptor wire may be deposited on the major outer surface of the sheet material without being cut.

[0016] The wire feed may be disposed vertically above the sheet material, preferably at the location of deposition on the major outer surface.

[0017] As used herein, the term "disposed vertically above" is understood to be in a projection of the plane of the sheet material or in a projection of the plane that contacts the sheet material at the location of wire deposition above the sheet material.

[0018] As used herein, the term "wire deposition location" may refer to the current surface portion of the sheet material where the susceptor wire is deposited on a major outer surface of the sheet material at a given time during the deposition process.

[0019] By providing a wire supply disposed vertically above the sheet material, the susceptor wire may be simply deposited by gravity onto the outer major surface of the sheet material. Of course, additional elements, such as guide elements and / or rollers for the susceptor wire, may be provided to facilitate deposition of the susceptor wire onto the outer major surface of the sheet material.

[0020] Alternatively, the wire feed may be disposed vertically below the sheet material at the location of deposition on the major surface.

[0021] According to another alternative, the wire feed may preferably be arranged horizontally beside the sheet material at the point of deposition on the main surface. As used herein, the term "horizontally arranged beside" is understood to be placed in the projection of a plane of the sheet material when the wire feed is in an operative state, or in the projection of a plane tangent to the sheet material at the point of deposition transverse to the sheet material.

[0022] During deposition of the susceptor wire on the outer major surface of the sheet material, the sheet material and the wire supply may be moved relative to one another, either continuously or in steps, thus allowing the susceptor wire to be deposited on most of the outer major surface of the sheet material, which is particularly advantageous when the sheet material is provided as a continuous substrate sheet.

[0023] Specifically, while the susceptor wire is being deposited on the outer major surface of the sheet material, the sheet material may be moved in a conveying direction relative to (specifically, past) the wire supply, either continuously or stepwise. This allows for deposition of the susceptor wire on a large portion of the outer major surface of the susceptor material, preferably continuous deposition of the susceptor wire on the outer major surface of a sheet material provided as a continuous substrate sheet. The conveying direction may be parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at the location of wire deposition. This is also particularly advantageous when the sheet material is provided as a continuous substrate sheet, thereby optimizing the method of applying the susceptor wire to the aerosol-forming substrate.

[0024] Immediately prior to deposition onto the outer major surface of the sheet material, the projection of the length extension of the susceptor wire onto a plane defined by the sheet material or onto a plane tangent to the sheet material at the location of wire deposition may be substantially parallel to the transport direction, in which case the substantial parallelism of the length extension and the projection of the transport direction allows for improved deposition of the susceptor wires, as the alignment of the susceptor wires is supported by the movement of the sheet material in the transport direction, thus allowing for substantially parallel alignment of the susceptor wires relative to each other and relative to the transport direction.

[0025] Preferably, the sheet material may be moved relative to (particularly past) the wire feed in a conveying direction by a conveyor belt or by one or more rollers.

[0026] Alternatively, or additionally, during deposition of the susceptor wire on the outer major surface of the sheet material, the wire feeder may move relative to (specifically, across / along) the sheet material in a plane parallel to a plane defined by the sheet material or in a plane parallel to a plane tangent to the sheet material at the location of wire deposition. Specifically, the wire feeder may move in a direction parallel to the projection of the length extension of the susceptor wire onto the respective plane immediately prior to deposition on the outer major surface of the sheet material. Thus, the susceptor wire may be deposited on the outer major surface of the sheet material, with its length extension extending in any arbitrary direction. As an example, the substrate wire may be deposited on the outer major surface of the sheet material in a pattern extending obliquely to the transport direction, in a sinusoidal pattern, in a staggered (sawtooth) pattern, or even in a pattern perpendicular to the transport direction.

[0027] In a preferred configuration, the angle between the length extension of the susceptor wire as it leaves the wire feed and the plane defined by the sheet material may be in the range of 0 to 90 degrees, specifically 0 to 80 degrees, and preferably 10 to 45 degrees. The preferred angle range has been shown to be particularly efficient for susceptor wire deposition. Alternatively, the angle between the length extension of the susceptor wire as it leaves the wire feed and the plane tangent to the sheet material at the location of wire deposition may be in the range of 0 to 90 degrees, specifically 0 to 80 degrees, and preferably 10 to 45 degrees.

[0028] The aerosol-forming substrate may preferably be made from a substrate slurry cast into the form of a sheet material, and the susceptor wire is deposited on the cast substrate slurry, particularly before drying the cast substrate slurry. This is done, particularly to achieve improved bonding of the susceptor wire with the sheet material during subsequent drying. Depending on the hardness of the sheet material, particularly the cast substrate slurry, the susceptor wire may also be at least partially embedded in the substrate sheet after or during deposition, either based on the specific setup of the method (or equipment) according to the present disclosure or thanks to dedicated means such as at least one pressing roller or the like.

[0029] As already mentioned above, the aerosol-forming substrate in the form of a sheet material may be a continuous substrate sheet.

[0030] Preferably, the susceptor wire may be deposited on the major outer surface of the sheet material during or after crimping the continuous substrate sheet. Specifically, the susceptor wire may be deposited on the major outer surface of the sheet material during or after crimping the continuous substrate sheet in the longitudinal direction. The longitudinal direction may specifically be the machine direction of the continuous substrate sheet, preferably parallel to the conveying direction. Because the sheet material is corrugated during or after crimping, depositing the susceptor wire during or after crimping has the advantage that the created corrugations facilitate containment of the susceptor wire during deposition, thereby simplifying deposition and improving alignment and distribution of the susceptor wire. In addition, the susceptor wire contained within the corrugations may be at least partially surrounded by the sheet material. Thus, the sheet material may provide a clamping effect for the susceptor wire.

[0031] To further improve alignment of the susceptor wire, the susceptor wire provided from the wire feed may be fed into the grooves of a crimping roller used to crimp the continuous substrate sheet, so that the susceptor wire is deposited within the corrugations formed during crimping. Preferably, the number of corrugations in the continuous substrate sheet along a direction perpendicular to the longitudinal axis of the crimp is in the range of 2 corrugations per centimeter of sheet material to 12 corrugations per centimeter of sheet material, specifically about 10 corrugations per centimeter of sheet material.

[0032] To improve retention of the susceptor wire on the outer major surface of the sheet material, an adhesive may be applied to the outer major surface of the sheet material prior to depositing the susceptor wire thereon. Specifically, the adhesive may include glycerol.

[0033] The maximum transverse dimension of the susceptor wire may be preferably in the range of 10 micrometers to 500 micrometers, specifically 20 micrometers to 150 micrometers, and preferably 40 micrometers to 100 micrometers. Specifically, the maximum transverse dimension of the susceptor wire may be 500 micrometers or less, specifically 300 micrometers or less, preferably 200 micrometers or less, and more preferably 100 micrometers or less.

[0034] At least a portion of the susceptor wire may preferably have a constant maximum transverse dimension, particularly a constant cross-sectional area, along the length extension of the susceptor wire.

[0035] As used herein, the term "maximum transverse dimension" refers to the largest dimension of the susceptor wire perpendicular to its major dimension (length extension).

[0036] Preferably, the maximum transverse dimension has an upper as well as a lower limit, so that the maximum transverse dimension of the susceptor wire may be 500 micrometers or less, particularly 300 micrometers or less, preferably 200 micrometers or less, and more preferably 100 micrometers or less.

[0037] The heating efficiency also depends on the density of the susceptor wires within the aerosol-forming substrate. The higher the density, the greater the heating efficiency. Preferably, the linear density of the susceptor wires within the aerosol-forming substrate along a direction perpendicular to their length extension is in the range of 2 to 12 wires per centimeter of sheet material, specifically about 10 wires per centimeter of sheet material.

[0038] In general, the susceptor wire may have any cross-sectional shape in a plane perpendicular to its length extension. Preferably, the cross-section of the susceptor wire may have a circular, oval, elliptical, triangular, rectangular, square, or polygonal shape. If the cross-section is circular, the aforementioned maximum transverse dimension of the susceptor wire corresponds to the diameter of the susceptor wire, which is greatest along the length extension of the susceptor wire. If the cross-section is oval or elliptical, the aforementioned maximum transverse dimension of the susceptor wire corresponds to the length of the major axis of the oval or elliptical cross-section, which is greatest along the length extension of the susceptor wire. If the cross-section is square or generally rectangular, the aforementioned maximum transverse dimension of the susceptor wire corresponds to the length of the edge / long edge of the square / rectangular cross-section.

[0039] Generally, the term "susceptor wire," as used herein, refers to a susceptor element comprising a susceptor material capable of converting electromagnetic energy into heat when subjected to an alternating magnetic field. This may be the result of at least one of hysteresis loss and eddy currents induced in the susceptor material, depending on the electrical and magnetic properties of the susceptor material. Hysteresis loss occurs in ferromagnetic or ferrimagnetic susceptor materials due to magnetic domains in the material being switched under the influence of the alternating electromagnetic field. Eddy currents may be induced if the susceptor material is electrically conductive. In the case of an electrically conductive ferromagnetic susceptor or an electrically conductive ferrimagnetic susceptor, heat can be generated due to both eddy currents and hysteresis loss.

[0040] Preferably, the susceptor wire may include a susceptor material that is electrically conductive and either ferromagnetic or ferrimagnetic. Specifically, the susceptor material of the susceptor wire may be non-conductive but either ferromagnetic or ferrimagnetic. Alternatively, the susceptor material of the susceptor wire may be electrically conductive but neither ferromagnetic nor ferrimagnetic.

[0041] The susceptor material of the susceptor wire may include or consist of a metal, such as ferritic iron, or stainless steel, particularly stainless steel grade 410, grade 420, or grade 430. Alternatively, the susceptor material may include a ferrimagnetic ceramic.

[0042] In addition to the susceptor material, the susceptor wire may further include a ferromagnetic or ferrimagnetic temperature marker material, where the susceptor material is optimized for heat loss and therefore heating efficiency, while the temperature marker material is a magnetic (ferromagnetic or ferrimagnetic) material chosen to have a Curie temperature that essentially corresponds to a predefined temperature point in the heating process.

[0043] The temperature marker material may have a Curie temperature of less than 500° C., preferably 400° C. or less, specifically 390° C. or less. For example, the temperature marker material of the susceptor wire may have a Curie temperature in the range of 180° C. to 420° C., specifically 210° C. to 380° C., preferably 250° C. to 380° C. Although the temperature marker material is primarily a functional material that provides a temperature marker by its Curie temperature, it may also contribute to the induction heating process of the susceptor arrangement.

[0044] The temperature marker material of the susceptor wire may include or consist of nickel or a nickel alloy.

[0045] The susceptor wire may be formed such that the susceptor material is at least partially, and preferably completely, surrounded or covered by the temperature marker material.

[0046] In addition, the susceptor wire may comprise an outer protective coating surrounding the susceptor material and, if present, the temperature marker material. Preferably, the protective coating is an anti-corrosion coating. Advantageously, the protective coating makes the susceptor wire resistant to external influences, particularly corrosive influences.

[0047] It is also possible for the susceptor material of the susceptor wire itself to have temperature marker functionality, i.e., the susceptor wire may comprise a single material that acts both as a susceptor material and as a temperature marker material.

[0048] The present disclosure also relates to an apparatus for applying a susceptor wire to an aerosol-forming substrate. The apparatus may be used in accordance with the method for applying a susceptor wire to an aerosol-forming substrate described above. Therefore, descriptions of the method of the present disclosure may be applied to the apparatus according to the present disclosure, as appropriate.

[0049] The apparatus includes a wire supply for providing a plurality of susceptor wires and a substrate supply for providing an aerosol-forming substrate in the form of a sheet material to or past the wire supply, enabling the wire supply to deposit the susceptor wires on a major outer surface of the sheet material.

[0050] Preferably, the wire supply is constructed and arranged to provide and deposit a plurality of susceptor wires in substantially parallel alignment with one another on the outer major surface of the sheet material.

[0051] As previously mentioned, the wire feed may comprise one or more bobbins on which the susceptor wire is provided and from which it is fed to the sheet material. Multiple susceptor wires may be provided coiled on a single bobbin, or preferably, the wire feed may comprise multiple bobbins, one for each susceptor wire.

[0052] The bobbins each have a bobbin axis, and specifically the bobbins may be arranged with adjacent parallel bobbin axes, preferably adjacent coaxially arranged.

[0053] The substrate supply may preferably comprise a conveyor belt or one or more rollers for moving the aerosol-forming substrate, in the form of a sheet material, either continuously or stepwise, relative to (e.g., past) the wire supply in a conveying direction, which may preferably be parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at the location of wire deposition.

[0054] Specifically, the wire supply may be configured and arranged so that immediately prior to deposition onto the major outer surface of the sheet material, a projection of the length extension of the susceptor wire onto a plane defined by the sheet material or onto a plane tangent to the sheet material at the location of wire deposition is substantially parallel to the transport direction.

[0055] Also, according to the present disclosure, the wire feeder may be configured to move relative to (specifically, across / along) the sheet material in a plane parallel to a plane defined by the sheet material or a plane parallel to a plane tangent to the sheet material at the location of wire deposition, in a direction parallel to a projection of the length extension of the susceptor wire onto the respective plane, particularly immediately prior to deposition onto the major outer surface of the sheet material.

[0056] In a preferred installation, the angle between the length extension of the susceptor wire as it leaves the wire feed and the plane defined by the sheet material may be in the range of 0 to 90 degrees, specifically 0 to 80 degrees, and preferably 10 to 45 degrees. Similarly, the angle between the length extension of the susceptor wire as it leaves the wire feed and the plane tangent to the sheet material at the location of wire deposition may be in the range of 0 to 90 degrees, specifically 0 to 80 degrees, and preferably 10 to 45 degrees.

[0057] As used herein, the term "aerosol-generating article" refers to an article comprising at least one aerosol-forming substrate capable of releasing a volatile compound to form an aerosol when heated. The aerosol-generating article may be a consumable product, particularly one that is discarded after a single use. For example, the article may be an elongated or rod-shaped article. The elongated or rod-shaped article may have a shape similar to that of a conventional cigarette. Specifically, such an article may have a circular, oval, elliptical, square, rectangular, triangular, or polygonal cross-section. As another example, the article may be a cartridge containing a liquid aerosol-forming substrate to be heated.

[0058] As used herein, the term "aerosol-forming substrate" refers to a substrate formed from or including an aerosol-forming material capable of releasing a volatile compound upon heating to generate an aerosol. Preferably, the aerosol-forming substrate is intended to be heated, rather than combusted, to release the aerosol-forming volatile compound. Consequently, such a substrate may be referred to as a heat-non-combustion aerosol-forming substrate. Similarly, an aerosol-generating article including such an aerosol-forming substrate may be referred to as a heat-non-combustion aerosol-generating article.

[0059] Generally, the aerosol-forming substrate may include at least one aerosol former and at least one sensory material, both of which are volatilizable when heated. The sensory material may include at least one of a tobacco-containing material, a nicotine-containing material, and a flavoring material. Examples of suitable aerosol formers include glycerin and propylene glycol. Examples of flavoring materials may include plant extracts and natural or artificial flavors.

[0060] The aerosol-forming substrate may be a solid aerosol-forming substrate, or a gel-like aerosol-forming substrate, or any combination thereof.

[0061] As noted above, the aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds that are released from the substrate upon heating. Specifically, the aerosol-forming substrate may comprise a reconstituted tobacco material or a tobacco-containing slurry. As a result, the aerosol-generating article may be a tobacco-containing article. Alternatively, or additionally, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may also comprise other additives and ingredients, such as nicotine or flavoring agents.

[0062] The aerosol-forming substrate may also be a paste-like material, a sachet of porous material containing the aerosol-forming substrate, or, for example, loose tobacco mixed with a gelling or adhesive agent, which may include a common aerosol former such as glycerin, which is compressed or molded into a plug.

[0063] The aerosol-forming substrate is made from a sheet material. For example, the aerosol-forming substrate may be made from a crimped tobacco sheet containing tobacco material, organic fibers, a binder, and an aerosol former. Alternatively, the aerosol-forming substrate may be made from a sheet material containing a nicotine-containing material, organic fibers, a binder, and an aerosol former. As yet another alternative, the aerosol-forming substrate may be made from a sheet material containing a tobacco cut filler. To this extent, the aerosol-generating article has been found to be simple to manufacture, particularly when the susceptor wire is applied to the aerosol-forming substrate when it is in the form of a sheet material, with respect to the preferred alignment of the susceptor wire with respect to the predefined reference axis of the article. This may be the result of a manufacturing process that includes deposition of the susceptor wire on the outer surface of the sheet material, either during a primary process in which the sheet material is manufactured, or during a secondary process in which the sheet material is machined and combined with other semi-finished products to obtain the final product. As a result of this, the susceptor wire may ultimately be disposed on the outer surface of the sheet material, or may be at least partially embedded within the sheet material near the outer surface of the sheet material. This can be seen even when the sheet material is subsequently machined, for example, crimped and assembled, such as to form a substrate plug in the final article.

[0064] The present invention is defined in the claims. However, below 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 described above, for example, with any one or more features of other examples, embodiments, or aspects described herein.

[0065] Example Ex1: A method for applying a susceptor wire to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article, the method comprising the steps of providing an aerosol-forming substrate in the form of a sheet material, providing a plurality of susceptor wires from a wire supply, and depositing the plurality of susceptor wires on a major outer surface of the sheet material.

[0066] Example Ex2: A method according to example Ex1, wherein a plurality of susceptor wires are provided and deposited on a major outer surface of the sheet material in substantially parallel alignment with respect to one another.

[0067] Embodiment Ex3: The method according to any one of the preceding embodiments Ex1-Ex2, wherein the plurality of susceptor wires are continuous susceptor wires, each provided from a bobbin that is part of a wire supply.

[0068] Example Ex4: A method according to any one of the preceding examples Ex1 to Ex3, wherein the wire feed is disposed vertically above the sheet material at the deposit on the outer major surface.

[0069] Example Ex5: A method according to any one of the preceding examples Ex1 to Ex4, wherein the sheet material and the wire feed are moved relative to one another while depositing the susceptor wire onto the outer major surface of the sheet material.

[0070] Example Ex6: A method according to any one of the preceding examples Ex1 to Ex5, wherein, while the susceptor wire is deposited on the main outer surface of the sheet material, the sheet material is moved (specifically past) in a conveying direction relative to the wire supply, the conveying direction being preferably parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at the location of wire deposition.

[0071] Example Ex7: A method according to example Ex6, wherein immediately before deposition onto the main outer surface of the sheet material, the projection of the length extension of the susceptor wire onto a plane defined by the sheet material or onto a plane tangent to the sheet material at the location of wire deposition is substantially parallel to the conveying direction.

[0072] Example Ex8: A method according to any one of examples Ex6 or Ex7, wherein the sheet material is moved relative to (e.g., past) the wire feed in the conveying direction by a conveyor belt or by one or more rollers.

[0073] Example Ex9: A method according to any one of the preceding examples Ex1 to Ex8, wherein during deposition of the susceptor wire on the main outer surface of the sheet material, the wire feed is moved relative to (specifically across / along) the sheet material in a plane parallel to a plane defined by the sheet material or a plane parallel to a plane tangent to the sheet material at the location of wire deposition, in a direction parallel to the projection of the length extension of the susceptor wire onto the respective plane, particularly immediately before deposition onto the main outer surface of the sheet material.

[0074] Example Ex10: A method according to any one of the preceding examples Ex1 to Ex9, wherein the angle between the length extension of the susceptor wire when it leaves the wire feed section and the plane defined by the sheet material is in the range of 0 degrees to 90 degrees, particularly 0 degrees to 80 degrees, preferably 10 degrees to 45 degrees; or the angle between the length extension of the susceptor wire when it leaves the wire feed section and the plane tangent to the sheet material at the location of wire deposition is in the range of 0 degrees to 90 degrees, particularly 0 degrees to 80 degrees, preferably 10 degrees to 45 degrees.

[0075] Example Ex11: A method according to any one of examples Ex1 to Ex10, wherein the aerosol-forming substrate is made from a substrate slurry cast into the form of a sheet material, and a susceptor wire is deposited on the cast substrate slurry.

[0076] Example Ex12: A method according to example Ex11, wherein a susceptor wire is deposited on the outer major surface of the sheet material before drying the cast substrate slurry.

[0077] Example Ex13: The process according to any one of examples Ex1 to Ex12, wherein the aerosol-forming substrate in the form of a sheet material is a continuous substrate sheet.

[0078] Example Ex14: A method according to example Ex13, wherein the susceptor wire is deposited on a major outer surface of the sheet material during or after crimping the continuous substrate sheet, particularly during or after crimping the continuous substrate sheet in the longitudinal direction, specifically in the machine direction of the continuous substrate sheet.

[0079] Example Ex15: A method according to example Ex14, wherein a susceptor wire provided from a wire feeder is fed into the grooves of a crimping roller used to crimp a continuous substrate sheet, whereby the susceptor wire is deposited within the corrugations formed during crimping.

[0080] Example Ex16: The method according to any one of the preceding examples Ex1 to Ex15, wherein an adhesive is applied to the outer major surface of the sheet material before depositing the susceptor wire thereon.

[0081] Example Ex17: The method according to example Ex16, wherein the adhesive comprises glycerol.

[0082] Example Ex18: The method according to any one of the preceding examples Ex1 to Ex17, wherein the susceptor wire has a maximum transverse dimension in the range of 10 micrometers to 500 micrometers, specifically 20 micrometers to 150 micrometers, preferably 40 micrometers to 100 micrometers.

[0083] Example Ex19: The method according to any one of the preceding examples Ex1 to Ex18, wherein the susceptor wire has a maximum transverse dimension of 500 micrometers, particularly 300 micrometers, preferably 200 micrometers, more preferably 100 micrometers or less.

[0084] Example Ex20: The method according to any one of the preceding examples Ex1 to Ex19, wherein the cross section of the susceptor wire has a circular shape, or an oval shape, or an elliptical shape, or a triangular shape, or a rectangular shape, or a square shape, or a polygonal shape.

[0085] Example Ex21: The method according to any one of the preceding examples Ex1 to Ex20, wherein the susceptor wire comprises a susceptor material that is electrically conductive and either ferromagnetic or ferrimagnetic.

[0086] Example Ex22: The method according to example Ex21, wherein the susceptor material of the susceptor wire comprises or consists of a metal, for example ferritic iron, or stainless steel, in particular grade 410, grade 420, or grade 430 stainless steel, or a ferrimagnetic ceramic.

[0087] Example Ex23: The method according to any one of examples Ex21 or Ex22, wherein the susceptor wire further comprises a ferromagnetic or ferrimagnetic temperature marker material in addition to the susceptor material.

[0088] Example Ex24: The method according to example Ex23, wherein the temperature marker material of the susceptor wire comprises nickel or a nickel alloy or consists of nickel or a nickel alloy.

[0089] Example Ex25: Installation for applying a susceptor wire to an aerosol-forming substrate, particularly for use in a method according to any one of the preceding examples Ex1 to Ex24, comprising a wire supply for providing a plurality of susceptor wires, and a substrate supply for providing an aerosol-forming substrate in the form of a sheet material to or past the wire supply, enabling the wire supply to deposit the susceptor wire on a major outer surface of the sheet material.

[0090] Example Ex26: An apparatus according to example Ex25, wherein the wire supply is configured and arranged to provide and deposit a plurality of susceptor wires on a major outer surface of the sheet material in substantially parallel alignment with respect to each other.

[0091] Example Ex27: Installation according to any one of examples Ex25 or Ex26, wherein the wire supply comprises one or more bobbins on which the susceptor wire is provided and from which it is fed to the sheet material.

[0092] Example Ex28: Installation according to any one of examples Ex25 to Ex27, wherein the wire supply comprises a plurality of bobbins, one for each susceptor wire.

[0093] Example Ex29: An installation according to example Ex28, wherein the bobbins each have a bobbin axis and the bobbins are arranged parallel and adjacent to each other, in particular adjacent to each other and coaxial with respect to the bobbin axes.

[0094] Example Ex30: Installation according to any one of examples Ex25 to Ex29, wherein the substrate supply comprises a conveyor belt or one or more rollers for moving the aerosol-forming substrate in the form of a sheet material relative to (in particular past) the wire supply in a conveying direction, the conveying direction being preferably parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at the wire.

[0095] Example Ex31: Installation according to any one of examples Ex25 to Ex30, wherein the wire supply is constructed and arranged so that immediately prior to deposition onto a major outer surface of the sheet material, a projection of the length extension of the susceptor wire onto a plane defined by the sheet material or onto a plane tangent to the sheet material at the location of wire deposition is substantially parallel to the conveying direction.

[0096] Example Ex32: Installation according to any one of examples Ex25 to Ex31, wherein the wire feeder is configured to move relative to (specifically across / along) the sheet material in a plane parallel to a plane defined by the sheet material or a plane tangent to the sheet material at the location of wire deposition, in a direction parallel to the projection of the length extension of the susceptor wire onto the respective plane, in particular immediately prior to deposition onto a main outer surface of the sheet material.

[0097] Example Ex33: Installation according to any one of examples Ex25 to Ex32, wherein the wire feed section is constructed and arranged such that the angle between the length extension of the susceptor wire when it leaves the wire feed section and the plane defined by the sheet material is in the range of 0 degrees to 90 degrees, in particular 0 degrees to 80 degrees, preferably 10 degrees to 45 degrees, or the angle between the length extension of the susceptor wire when it leaves the wire feed section and the plane tangent to the sheet material at the location of wire deposition is in the range of 0 degrees to 90 degrees, in particular 0 degrees to 80 degrees, preferably 10 degrees to 45 degrees.

[0098] The embodiments will now be further described with reference to the schematic drawings (not to scale). [Brief explanation of the drawings]

[0099] [Figure 1] FIG. 1 shows a schematic top view of an installation according to the invention. [Figure 2] FIG. 2 shows a schematic side view of an installation according to the invention. [Figure 3] FIG. 3 shows a schematic side view of an installation according to another embodiment of the invention. [Figure 4] FIG. 4 shows a schematic top view of an installation according to another embodiment of the invention. [Figure 5] FIG. 5 shows a schematic representation of a deposition pattern of a susceptor wire according to the present invention. [Figure 6] FIG. 6 shows a schematic diagram of a deposition pattern of a susceptor wire according to another embodiment of the present invention. [Figure 7]FIG. 7 shows a schematic diagram of a deposition pattern of a susceptor wire according to yet another embodiment of the present invention. [Figure 8] FIG. 8 shows a schematic top view of an installation according to yet another embodiment of the present invention. [Figure 9] FIG. 9 shows a schematic side view of the installation of FIG. [Figure 10] FIG. 10 shows a schematic cross-sectional view of a crimped sheet material having a susceptor wire deposited thereon. DETAILED DESCRIPTION OF THE INVENTION

[0100] All embodiments shown in the figures are schematic and not to scale.

[0101] An embodiment of an apparatus 5 according to the present invention for applying a susceptor wire 1 to an aerosol-forming substrate according to the method of the present invention is shown schematically in a top view in FIG. 1 and a side view in FIG. 2. The apparatus 5 comprises a wire supply 6, which comprises a bobbin 7 and guide rollers 8. Four susceptor wires 1 are provided on the bobbin 7 in a coiled form. The apparatus 5 further comprises a substrate supply for providing an aerosol-forming substrate 9 in the form of a sheet material 10. In the example shown in FIG. 1, the sheet material 10 is in the plane of the drawing, but other orientations of the sheet material 10 are possible, as will be explained later. The sheet material 10 may be a finite sheet having a given length, or it may be a continuous substrate sheet, as suggested by the dashed lines.

[0102] The bobbins 7 and guide rollers 8 are disposed vertically above the sheet material 10 and are, for example, rotatably mounted on axes 11 and 12, respectively. The projections of the orientations of axes 11 and 12 each lie in the plane of the sheet material 10. The sheet material 10 is conveyed past the wire supply 6 in a conveying direction C, either continuously or stepwise, as will be explained later with reference to FIG. 2. The conveying direction C is preferably parallel to a plane defined by the sheet material 10 or to a plane tangent to the sheet material 10 at the location of wire deposition.

[0103] As the sheet material 10 moves past the wire feeder 6, the susceptor wire 1 is unwound from a bobbin 7 and deposited on a major outer surface of the sheet material 10 in an arrangement substantially parallel to each other and to the conveying direction C. To support correct alignment of the susceptor wire 1 with respect to the sheet material 10, guide rollers 8 may be provided in the grooves and / or the guide rollers 8 may be configured to provide a desired tension in the susceptor wire 1 during deposition. As an alternative to, or in addition to, movement of the sheet material 9 in the conveying direction C, the wire feeder 6 may move relative to the sheet material 10, specifically across / along the sheet material 10, in a plane parallel to a plane defined by the sheet material 10 or in a plane parallel to a plane tangent to the sheet material 10 at the location of wire deposition. Movement across the sheet material 10 is indicated by a double-headed arrow T, while movement along the sheet material 10 is indicated by a double-headed arrow A.

[0104] FIG. 2 shows a schematic side view of the installation 5 of FIG. 1. As can be seen from FIG. 2, a wire feed section 6 is disposed vertically above a sheet material 10. The sheet material 10 may be moved past the wire feed section 6 in a conveying direction C by one or more rollers 13 and / or one or more conveyor belts 14. When the susceptor wire 1 leaves the wire feed section 6, in the embodiment shown in FIG. 2, the angle 15 between the length extension L of the susceptor wire 1 when it leaves the guide roller 8 and a plane 16 parallel to the sheet material 10, indicated by the dashed line, is in the range of 0 to 90 degrees, preferably 0 to 80 degrees, and specifically 10 to 45 degrees.

[0105] FIG. 3 shows a schematic side view of another embodiment of the apparatus 5. While in the apparatus 5 shown in FIGS. 1 and 2, the sheet material 10 lies flat in a plane during deposition of the susceptor wire 1 on a major outer surface of the sheet material 10, in FIG. 3, the orientation of the plane of the sheet material 10 changes along the longitudinal direction. As a result, an angle 15, defined as the length extension L of the susceptor wire 1 as it leaves the wire feed section 6—in the example shown in FIG. 3, as it leaves the guide roller 8—and a plane 16, indicated by a dashed line, parallel to a plane 17 tangent to the sheet material 10 at a wire deposition location 18, is in the range of 0 to 90 degrees, preferably 0 to 80 degrees, and specifically 10 to 45 degrees. The conveying direction C is also parallel to the plane tangent to the sheet material 10 at the wire deposition location 17.

[0106] Figure 4 shows another embodiment of an apparatus 5 similar to the apparatus 5 shown in Figure 1. However, in the apparatus 5 of Figure 4, the susceptor wires 1 are each provided on a single bobbin 7. The bobbins 7 are arranged adjacent to each other on an axis 11 and are therefore coaxial. The transport of the sheet material 10 may be as shown in Figure 2 or Figure 3.

[0107] As described above, the wire feeder 6 may move relative to the sheet material 10, specifically across / along the sheet material 10, in a plane parallel to the plane defined by the sheet material 10 or parallel to the plane 17 tangent to the sheet material 10 at the wire deposition location 18. As an example, when the wire feeder 6 of the apparatus 5 shown in FIG. 1 or FIG. 4 moves across the sheet material 10 during deposition of the susceptor wire 1, as suggested by the double-headed arrow T, the susceptor wire 1 may be deposited on the major outer surface of the sheet material 10 in a sinusoidal pattern as shown in FIG. 5 or a staggered (sawtooth) pattern as shown in FIG. 6. The susceptor wire 1 is arranged such that the distance between two adjacent susceptor wires 1 is constant along the length L of the susceptor wire 1 in a direction perpendicular to the transport direction C and parallel to the plane defined by the sheet material 10 or the plane 17 tangent to the sheet material 10 at the wire deposition location 18.

[0108] As mentioned above, in alternative embodiments, the susceptor wire 1 may be cut to length either prior to or during deposition onto the outer major surface of the sheet material 10, as shown in Figure 7. In this regard, the wire supply 6 may include cutting means, e.g., a cutting roller, for cutting the susceptor wire 1 immediately prior to or during deposition onto the outer major surface of the sheet material 10. Alternatively, the susceptor wire may be provided to the wire supply 6 already cut to length.

[0109] When the susceptor wire 1 is continuously deposited on the major outer surface of the sheet material 10, the susceptor wire 1 is preferably cut simultaneously with the sheet material 10 in a subsequent step in which the sheet material 10 may be crimped and assembled to form a substrate element for an aerosol-generating article.

[0110] In this regard, FIG. 8 shows another embodiment of an apparatus 5 similar to the apparatus shown in FIGS. 1 to 4. The apparatus 5 is shown schematically in a top view in FIG. 8 and in a side view in FIG. 9. The arrangement of the bobbins 7 may be as shown in FIG. 1 or 4. The apparatus 5 further includes a crimping unit 19. The crimping unit 19 may include intermeshing grooved rollers 20 and 21 for crimping the sheet material 10, preferably with their longitudinal axes parallel to the machine direction of the apparatus 5, which in the embodiment shown in FIGS. 8 and 9 is also parallel to the conveying direction C. Thus, the crimped sheet material 10 is corrugated as it is conveyed between the grooved rollers 20 and 21. The susceptor wire 1 is then deposited on the sheet material 10 according to the embodiment shown in FIGS. 8 and 9 during the crimping of the sheet material 10. Alternatively, the susceptor wire 1 may be deposited on the sheet material 10 after crimping. The susceptor wire is guided between grooved rollers 20 and 21, which causes the susceptor wire 1 to be deposited within the corrugations (indicated by the dotted lines) of the sheet material 10, as exemplarily shown in the schematic cross-sectional view of the sheet material 10 after crimping in FIG.

[0111] Deposition of the susceptor wire 1 during or after crimping is particularly advantageous because the sheet material 10 is corrugated, with the resulting corrugations advantageously accommodating the susceptor wire 1 during deposition, thereby simplifying deposition and improving parallel alignment and distribution of the susceptor wire 1. Additionally, the susceptor wire 1 accommodated within the corrugations may be at least partially surrounded by the sheet material 10. Thus, the sheet material 10 may provide a clamping effect for the susceptor wire 1. Alternatively, or additionally, an adhesive, specifically glycerol, may be applied to the outer major surface of the sheet material to increase the adhesiveness of the susceptor wire 1 when deposited.

[0112] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± 5%. Within this context, the number A may be considered to include a numerical value that is within the typical standard error for measurement of the property that the number A modifies. In some instances, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 1. A method for applying a susceptor wire to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article, comprising: - providing an aerosol-forming substrate in the form of a sheet material; - providing a plurality of susceptor wires from a wire supply; - depositing said plurality of susceptor wires on a major outer surface of said sheet material; The method wherein the aerosol-forming substrate is made from a substrate slurry cast into the form of a sheet material, and the susceptor wire is deposited on the cast substrate slurry.

2. The method of claim 1 , wherein the plurality of susceptor wires are provided and deposited on the outer major surface of the sheet material in substantially parallel alignment with respect to one another.

3. The method of any one of claims 1 to 2, wherein the plurality of susceptor wires are continuous susceptor wires, each provided from a bobbin that is part of the wire supply.

4. 4. The method according to claim 1, wherein, during deposition of the susceptor wire on the outer main surface of the sheet material, the sheet material is moved relative to (in particular past) the wire supply in a transport direction, the transport direction being preferably parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at the location of wire deposition.

5. 5. The method according to claim 1, wherein the angle between the length extension of the susceptor wire when it leaves the wire feed section and a plane defined by the sheet material is in the range of 0 to 90 degrees, in particular 0 to 80 degrees, preferably 10 to 45 degrees, or the angle between the length extension of the susceptor wire when it leaves the wire feed section and a plane tangent to the sheet material at the location of wire deposition is in the range of 0 to 90 degrees, in particular 0 to 80 degrees, preferably 10 to 45 degrees.

6. The method of any one of claims 1 to 5, wherein the plurality of susceptor wires are continuous susceptor wires.

7. The method of any one of claims 1 to 6, wherein the susceptor wire is deposited on the outer major surface of the sheet material before drying the cast substrate slurry.

8. A method according to any one of claims 1 to 7, wherein the aerosol-forming substrate in the form of a sheet material is a continuous substrate sheet.

9. 9. The method of claim 8, wherein the susceptor wire is deposited on the outer major surface of the sheet material during or after crimping the continuous substrate sheet, particularly during or after crimping the continuous substrate sheet longitudinally, specifically in the machine direction of the continuous substrate sheet.

10. 10. The method of claim 9, wherein the susceptor wire provided from the wire supply is fed into grooves of a crimping roller used to crimp the continuous substrate sheet, whereby the susceptor wire is deposited within the corrugations formed during crimping.

11. 11. The method according to any one of claims 1 to 10, wherein the susceptor wire has a maximum transverse dimension in the range of 10 micrometers to 500 micrometers, particularly 20 micrometers to 150 micrometers, preferably 40 micrometers to 100 micrometers.

12. The method according to any one of the preceding claims, wherein the susceptor wire has a maximum transverse dimension of 500 micrometers, particularly 300 micrometers, preferably 200 micrometers, more preferably 100 micrometers or less.

13. The method of any one of claims 1 to 12, wherein the susceptor wire comprises a susceptor material that is electrically conductive and either ferromagnetic or ferrimagnetic.

14. 14. The method of claim 13, wherein the susceptor material of the susceptor wire comprises or consists of a metal, such as ferritic iron, or stainless steel, particularly grade 410, grade 420, or grade 430 stainless steel, or a ferrimagnetic ceramic.

15. An installation for applying a susceptor wire to an aerosol-forming substrate, in particular for use in the method according to any one of claims 1 to 14, comprising: a wire supply for providing a plurality of susceptor wires; a substrate supply section for providing an aerosol-forming substrate made from a substrate slurry cast into the form of a sheet material to or past the wire supply section, the wire supply section enabling the wire supply section to deposit the susceptor wire onto a major outer surface of the sheet material, the susceptor wire being deposited onto the cast substrate slurry.

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