EP4669140A1

EP4669140A1 - METHOD AND DEVICE FOR APPLYING OLDER SUSCEPTOR ELEMENTS TO AN AEROSOL-GENERATING SUBSTRATE

Info

Publication number: EP4669140A1
Application number: EP24705533.8A
Authority: EP
Inventors: Oleg Mironov; Andreas Michael ROSSOLL; Alessio DI GIUSEPPE; Lorenzo BENASSI; Julien Vidal
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2023-02-22
Filing date: 2024-02-21
Publication date: 2025-12-31
Also published as: CN120731017A; JP2026505673A; KR20250150109A; WO2024175660A1

Abstract

The present invention relates to a method and an apparatus (9) for applying elongated susceptor elements (3) 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 a sheet material (15); providing elongated susceptor elements (3); suppling the elongate susceptor elements (3) to and passing them through a screening device (1) comprising a screen (4) having a plurality of elongate screen openings (5) arranged in parallel along an alignment axis of the screen (4) with respect to their longitudinal axes; depositing the elongated susceptor elements (3), which are discharged from the screen (4) in at least partially alignment, on a main surface of the sheet material (15), preferably under the influence of gravity.

Description

METHOD AND APPARATUS FOR APPLYING ELONGATED SUSCEPTOR ELEMENTS TO AN AEROSOL-FORMING SUBSTRATE

The present disclosure relates to a method of applying elongate susceptor elements to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article. The present disclosure further relates to an apparatus for applying elongate susceptor elements to an aerosol-forming substrate, in particular for use in a method according to the present disclosure.

Aerosol-generating systems using induction heating for generating inhalable aerosols are generally known from prior art. Such systems may comprise an inductively heating aerosolgenerating device and a separate aerosol-generating article for use with the device. Among other components, the article may include an aerosol-forming substrate capable to form an inhalable aerosol when heated, and an inductively heatable susceptor arrangement in thermal proximity or direct physical contact with the substrate for heating the same. Inductive heating of the susceptor arrangement is accomplished by interaction of the susceptor arrangement with an alternating magnetic field that is provided by the aerosol-generating device. In 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 up to a temperature sufficient to release volatile compounds from the heated substrate, which subsequently can cool down to form an aerosol.

Depending on the type of substrate and the shape of the article, different configurations of susceptor element susceptor arrangements are known. As an example, the article may comprise a single solid susceptor element, such as a susceptor strip, that is embedded in a solid or gel-like aerosol-forming substrate within a substrate portion of the article. While solid susceptor element are easily available at low cost, they form a single central heat source which can result in inhomogeneous temperature distribution over the substrate portion. This is because direct heating of the substrate only occurs in the immediate vicinity of the susceptor element, while peripheral regions of the substrate portions are heated only indirectly by means of heat conduction across adjacent substrate layers. In particular, the high temperature gradient may cause the inner regions of the substrate portion in the vicinity of the susceptor element to overheat, whereas the temperature in the peripheral regions of the substrate portion may be too low for volatilizing the substrate. Moreover, the heating efficiency of this configuration is rather sensitive to a proper positioning of the susceptor element within the substrate. All this may cause a non-optimal exploitation of the aerosol-forming substrate. Alternatively, articles have been proposed that comprise spherical or quasi-spherical susceptor particles homogenously disturbed throughout the aerosol-forming substrate. Whilst leading to a more homogenous heating of the substrate, the heating efficiency of this susceptor configuration is limited which may also impact the extraction efficiency. Therefore, it would be desirable to have an inductively heatable aerosol-forming substrate and an apparatus for manufacturing such an aerosol-forming substrate with the advantages of prior art solutions, whilst mitigating their limitations. In particular, it would be desirable to have an aerosol-forming substrate which provide a more efficient heating and exploitation of the aerosolforming substrate.

According to an aspect of the present disclosure, there is provided a method of applying elongate susceptor elements to an aerosol-forming substrate for use in an inductively heatable aerosol-generating article. The method comprises the steps of: providing an aerosol-forming substrate in the form a sheet material and of providing elongate susceptor elements. The provided elongate susceptor elements are then supplied to a screening device comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes and are then passed through said plurality of elongate screen openings of the screen. The elongate susceptor element are then deposited on a main surface of the sheet material, after being discharged from the screen in at least partial alignment. This is in particular done under the influence of gravity. The sheet material may be provided as a finite sheet material or as a continuous substrate sheet. The screen therefore works as a sieve, wherein depending on the dimensions of the elongate screen openings and their orientation, only elongate susceptor elements within a given alignment range are allowed to pass through the screen and are consequently discharged on the main surface of the sheet material in at least partial alignment.

As used herein, the term "elongate susceptor element" refers to a susceptor element having a greater extent in one predominant dimension than in the two remaining dimensions perpendicular to the predominant dimension. As such, the elongate susceptor element may also be denoted as I D-elongate susceptor element (synonym for one-dimensionally-elongate susceptor element) or quasi-1 D susceptor element (synonym for quasi-one-dimensional susceptor element). In particular, the term "elongate susceptor element" may refer to a susceptor element that has a length dimension greater than any transverse dimension perpendicular to the length dimension. More particularly, the I D-elongate susceptor element may be an elongate or a prolate susceptor element.

Although the present invention is described herein with respect to elongate susceptor elements having a length dimension greater than any transverse dimension perpendicular to the length dimension, that is, with respect to I D-elongate susceptor element having a greater extent in one predominant dimension than in the two remaining dimensions perpendicular to the predominant dimension, it equally applies to susceptor elements having a greater extent in two (perpendicular) predominant dimensions than in the remaining dimension perpendicular to the predominant dimensions. Such susceptor elements may also be denoted as 2D-elongate susceptor elements. In particular, the present invention equally applies to susceptor elements which have a length dimension and a width dimension greater than a thickness direction, wherein the length dimension may be either greater than or substantially similar to the width dimension. More particularly, the present invention equally applies to susceptor elements which have one of an oblate cylindrical shape, such as coin shape, or an oblate-ellipsoidal shape, such as a lens shape, or a flake shape or plate shape. For these susceptor elements, the same features and advantages as described herein with respect to (I D-)elongate susceptor element equally apply and can be equally formulated by basically replacing the term "maximum length dimension of the (I D-)elongate susceptor element(s)" by "maximum extent of the 2D-elongate susceptor element(s) in the two predominant dimensions" and "maximum transverse dimension of the (1 D- )elongate susceptor element(s)" by a "maximum extent of the 2D-elongate susceptor element(s) in the remaining (non-prominent) dimension".

As compared to a single solid susceptor element, usage of a plurality of elongate susceptor elements which are dispersed throughout the aerosol-forming substrate advantageously results in a more homogenous heat distribution over the substrate without any significant temperature gradients across different substrate regions. Furthermore, where the susceptor material of the susceptor elements has a high thermal conductivity, the homogeneity of the heat distribution is further enhanced by the fact that a substrate comprising a plurality of susceptor elements dispersed therein exhibits an increased equivalent thermal conductivity as compared to a substrate without susceptor elements or with a single solid susceptor element only. Moreover, in achieving a homogeneous heat distribution, the proposed susceptor arrangement is less sensitive to the positioning of the susceptor elements as compared to a single solid susceptor element.

Most important, it was found that the geometry, in particular the relative dimensions of the susceptor elements have a major impact on the heating efficiency and thus on the extraction efficiency of the substrate. In this regard, it was found that susceptor elements having an elongate shape are less prone to demagnetization effects as compared to rather equidimensional susceptor elements, such as spherical or quasi-spherical susceptor particles. This can be explained as follows: When placing a susceptor element in an external magnetic field, it becomes progressively magnetized. As the external field increases, so does the internal magnetization. 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 element causes an accumulation of magnetic charge density at opposite ends of the susceptor element as seen in the direction of the external magnetic field. As a consequence, the susceptor element generates a magnetic field that causes a self-interaction with its material. This field lies along the same direction as the external magnetic field, but points opposite to it, and thus is termed the demagnetization field. The demagnetizing field depends on the geometrical shape of the susceptor element, but not on its absolute dimensions. Provided the susceptor element responds to the external magnetic field changes, the demagnetizing field is generally assumed to be proportional to the magnetization in each direction, related by a geometry dependent constant of proportionality that is known as the demagnetization factor. The demagnetization factor depends on the shape of the susceptor element as well as on its relative orientation to the external magnetic field. To this extent, it has been found that an external magnetic field running through an elongate susceptor element, such as a susceptor element having the shape of a fiber or a thin rod, with a length dimension significantly greater than any transverse dimension perpendicular to the length dimension, generates a weaker or even negligible demagnetization field as compared to a non-elongate (equidimensional) susceptor element, such as a spherical or quasi-spherical susceptor element. This can be intuitively understood since in a properly aligned elongate susceptor element the accumulated magnetic charge densities at the opposite ends of the susceptor element are more spatially distanced from each other. This causes the demagnetizing field to significantly reduce its intensity and thus to have a lesser impact on the magnetization field, which is responsible for the power losses. As a result, power losses and thus heating efficiency is greater than for an elongate susceptor element than for a non-elongate (equidimensional) susceptor element, such as spherical or quasi- spherical susceptor element. This applies especially where the orientation of the magnetic field is substantially parallel to the length dimension of the elongate susceptor element, in which configuration the heating performance is at maximum. Yet, it has been found that the elongate susceptor elements do not necessarily need to be in perfect parallel alignment with the external magnetic field direction. Even if the susceptor elements are aligned in a certain angular range about the orientation of the external magnetic field, the overall heating performance is still higher than for a susceptor arrangement with randomly oriented susceptor elements.

Since the overall heating performance of the elongate susceptor elements increases with a decreasing deviation from an alignment substantially parallel to the alternating magnetic field used for induction heating, the elongate susceptor elements may be aligned preferably such that an angle between the length dimension of the elongate susceptor elements alignment axis of the screen is in a range between +30 degrees and -30 degrees, preferably between +25 degrees and -25 degrees, in particular between +10 degrees and -10 degrees. Therefore, the elongate susceptor elements may be deposited on the main surface of the sheet material in a similar alignment, thereby increasing the heating performance. As used herein, the terms "(at least) partial alignment" or "(at least) partially aligned" refer to this kind of alignment in the above-defined angular ranges.

As stated above, the heating performance is at maximum for a substantially parallel alignment. Accordingly, the elongate susceptor elements are preferably discharged from the screen being substantially parallel to the alignment axis of the screen. As used herein, the term "substantially parallel" is understood as "parallel ± 5° degrees deviation from a parallel arrangement". In general, the elongate susceptor elements may be even randomly oriented within the aerosol-forming substrate, although the overall heating performance is lower for a random orientation than for an ensemble of elongate susceptor elements which are aligned in a certain angular range or substantially in parallel to the alternating magnetic field. This is because when considering an ensemble of susceptor elements, the overall heating performance of an ensemble of randomly oriented elongate susceptor elements is still higher on statistical average than that of an ensemble of non-elongate susceptor elements.

With a method/apparatus according to the present disclosure, there is provided a method/apparatus that allows to at least partially align the elongate susceptor elements prior to the deposition of the elongate susceptor elements such that the at least partially aligned elongate susceptor elements can be discharged in at least partial alignment and deposited on the main surface of the sheet material in at least partial alignment.

Whenever in this disclosure a number or a range is given for a plurality of a objects, such as for the plurality of susceptor elements, this means that the number or the range applies to at least 60 percent, in particular at least 70 percent, more particularly at least 80 percent, especially at least 90 percent of all objects out of the plurality of a objects, preferably for all objects out of the plurality of a objects. For example, where the present disclosure states that the elongate susceptor elements are aligned such that an angle between the length dimension of the elongate susceptor elements and the alignment axis of the screen is in a range between +A degrees and -A degrees, this means that at least 60 percent, in particular at least 70 percent, more particularly at least 80 percent, especially at least 90 percent of all elongate susceptor elements are aligned such that an angle between the length dimension of the elongate susceptor elements and alignment axis of the screen is in a range between +A degrees and -A degrees.

In order to discharge the elongate susceptor elements on the main surface of the sheet material, in particular only by gravity, the screen may be preferably arranged vertically above the sheet material at a place of deposition on the main surface.

As used herein, the term “arranged vertically above” is understood as lying in a projection of a plane of the sheet material or a projection of a plane tangent to the sheet material at the place of deposition above the sheet material.

As used herein, the term “place of deposition” refers to the current surface portion of the sheet material where the elongate susceptor element are deposited at given time during the discharge and deposition process on the main surface of the sheet material.

By providing the screen arranged vertically above the sheet material, the elongate susceptor elements may be easily deposited on the main surface of the sheet material by gravity.

In order to deposit the elongated susceptor elements on a large surface area of the sheet material, the screen and the sheet material may be moved relative to each other during deposition of the elongate susceptor elements on the main surface of the sheet material. This is in particular advantageous when the sheet material is provided as a continuous substrate sheet.

In particular, during depositing the elongate susceptor elements on the main surface of the sheet material, the sheet material may be moved relative (in particular past) to the screen in a conveying direction, either continuously or stepwise. The conveying direction preferably being parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition.

In order to provide an optimal alignment of the elongate susceptor elements on the main surface of the sheet material, a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition may be substantially parallel to the conveying direction.

In a preferred configuration, the alignment axis of the screen may be substantially parallel to the conveying direction.

Movement of the sheet material relative to (in particular past) screen in the conveying direction, either continuously or stepwise, may be preferably achieved by means of a conveyor belt or by means of one or more rollers.

Again, in order to deposit the elongate susceptor elements on a large surface area of the sheet material, the screen may be moved relative to (in particular across) the sheet material in a direction transverse, preferably perpendicular to the conveying direction, during depositing the elongate susceptor elements on the main surface of the sheet material.

In particular, in order to deposit the elongate susceptor elements on a large surface area of the sheet material, during depositing the elongate susceptor elements on the main surface of the sheet material, the screen may be moved relative to (in particular across) the sheet material in a plane parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition. Movement may be especially in a direction transverse to the alignment axis of the screen and/or in a direction parallel to the alignment axis of the screen or parallel to a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition.

Good performances with respect to aligning the elongate susceptor elements may be in particular achieved with a configuration where the screen is arranged horizontally or is inclined along the alignment axis with respect to the horizontal, thereby also using gravity for the purpose of aligning and discharging the elongate susceptor element. An angle of inclination may be in particular in a range between 2 degrees and 45 degrees, preferably between 2 degrees and 20 degrees, more preferably between 5 degrees and 10 degrees.

For best results with regard to aligning and discharging the elongate susceptor elements, the screen may be preferably configured such that a maximum lateral dimension of the elongate screen openings perpendicular to their longitudinal axis is in a range between 0.5 and 1.5, in particular between 0.75 and 1.25, preferably between 0.9 and 1.1 times a mean length dimension of the elongate susceptor elements.

A cross-section of the elongate screen openings may have a rectangular shape or an elliptical shape or an obround shape. The cross-section of the elongate screen openings as used herein may be understood as the outline of the elongate screen openings as seen in a plan view on the screen plane.

Defined in absolute values, a maximum lateral dimension of the elongate screen openings perpendicular to the longitudinal axis may be in a range between 0.1 millimeter and 20 millimeter, in particular 0.25 millimeter and 10 millimeter, preferably between 0.5 millimeter and 5 millimeter.

The screening device may be preferably a vibrating screening device, and the screen may be, accordingly, a vibrating screen. The screening device may preferably comprise a vibration generator configured to vibrate the screen. The vibration generator may be in particular an ultrasonic vibration generator. A vibrating screen in is particular advantageous for conveying and distributing the elongate susceptor elements on the screen, and for sieving the elongate susceptor elements through the elongate screen openings and can avoid jamming of the elongate screen openings as well as increase the throughput of the elongate susceptor elements through the screen.

This can be further supported by a screening device comprising a brushing member, arranged movable relative the screen across an upstream side of the screen (the side of the screen where the elongate susceptor elements are provided). The brushing member may be configured to assist the elongated susceptor elements to pass through the elongate screen openings. The brushing element may be in particular move randomly on the upstream side of the screen as a consequence of the vibration of the screen.

To avoid clogging or clotting of the elongate susceptor elements, the screening device may be configured such to avoid electrostatic charging and/or magnetization of the elongate susceptor elements. In particular the screening device may comprise or consist of antistatic and/or antimagnetic materials.

Another possibility for depositing the elongate susceptor element over a large surface area of the sheet material may be the configuration of screen having a lateral dimension substantially corresponding to a lateral dimension of the sheet material.

The aerosol-forming substrate may be preferably made from a substrate slurry casted into the form of the sheet material, wherein the elongate susceptor elements are deposited on the casted substrate slurry, in particular prior to drying the casted substrate slurry. Depending on the firmness of the casted substrate slurry, the elongate susceptor elements may be at least partially embedded within the substrate sheet after or during deposition. As already cited above, the aerosol-forming substrate in the form of the sheet material may be a continuous substrate sheet, therefore enabling continuous deposition of the elongate susceptor elements on the continuous substrate sheet.

To further improve manufacturing of the aerosol-forming substrate, the elongate susceptor elements may be deposited on the main surface of the sheet material during or after crimping the continuous substrate sheet. In particular during or after crimping the continuous substrate sheet in a longitudinal direction. The longitudinal direction may be a machine direction of the continuous substrate sheet, preferably parallel to the conveying direction. Deposition of the elongate susceptor elements during or after crimping has the advantage that, since the sheet material is corrugated, the created corrugations are particularly advantageous for accommodating the elongate susceptor elements during depositing, thereby simplifying depositing and also improving alignment and distribution of the elongate susceptor elements.

In order to improve hold of the elongate susceptor elements and to avoid displacement of the elongate susceptor elements, a sticky agent may be applied to the main surface of the sheet material prior to depositing the elongate susceptor elements thereon. The sticky agent may in particular comprise glycerol.

As discussed above, the geometry, in particular the relative dimensions of the elongate susceptor elements have a major impact on the heating efficiency and thus on the extraction efficiency of the substrate. Therefore, the elongate susceptor elements may be selected such as having a ratio of a length dimension to a maximum transverse dimension greater than 4, in particular greater than 10, preferably greater than 20, more preferably greater than 25, even more preferably greater than 30, most preferably greater than 35. The term “maximum transverse dimension” as used herein refers to a greatest dimension of the elongate susceptor element perpendicular to the predominant dimension (length dimension). This ratio may be denoted as aspect ratio or form factor.

As used herein, the ratio of the maximum length dimension of an elongate susceptor element to the maximum transverse dimension of the elongate susceptor element perpendicular to the length dimension is also denoted as form factor or aspect ratio. Accordingly, the form factor of the elongate susceptor elements is greater than 4, in particular greater than 10, preferably greater than 20, more preferably greater than 25, even more preferably greater than 30, most preferably greater than 35.

Preferably, the ratio of the maximum length dimension to the maximum transverse dimension (the form factor) does not only have a lower limit but also an upper limit. Accordingly, the ratio of the maximum length dimension to the maximum transverse dimension of the elongate susceptor elements perpendicular to the (maximum) length dimension, that is, the form factor of the elongate susceptor elements may be a range between 4 and 500, in particular between 10 and 300, preferably between 20 and 200, more preferably between 30 and 100. In absolute values, a length dimension of the elongate susceptor elements may be in a range between 20 micrometer and 50 millimeter, in particular 100 micrometer and 16 millimeter, preferably between 0.5 millimeter and 5 millimeter. Such maximum length dimensions prove advantageous with regard to deposition according to the present disclosure.

Depending on the respective absolute values of the maximum length dimension, the respective absolute value of the maximum transverse dimension of the elongate susceptor elements is preferably chosen such that the form factor is above the above-defined lower limit, advantageously also within the above-defined preferred ranges. Accordingly, a maximum transverse dimension of the elongate susceptor elements may be in a range between 5 micrometer and 500 micrometer, in particular 10 micrometer and 150 micrometer, preferably 80 micrometer and 120 micrometer. In particular, a maximum transverse dimension of the elongate susceptor elements may be equal to or smaller than 500 micrometer, in particular 100 micrometer, preferably 50 micrometer, more preferably 25 micrometer.

The heating efficiency also depends on the density of the elongate susceptor elements within the aerosol-forming substrate. The higher the density, the larger the heating efficiency. Preferably, a (volume) density of the elongate susceptor elements within the aerosol-forming substrate is in a range between 0.001 susceptor elements per cubic millimeter and 30 susceptor elements per cubic millimeter, in particular between 0.1 susceptor elements per cubic millimeter and 10 susceptor elements per cubic millimeter. Likewise, a mass density of the elongate susceptor elements within the aerosol-forming substrate may be in a range between 0.002 milligram of susceptor mass per cubic millimeter and 0.3 milligram susceptor mass per cubic millimeter, in particular between 0.01 milligram of susceptor mass per cubic millimeter and 0.1 milligram of susceptor mass per cubic millimeter.

In general, the susceptor elements may have any geometrical shape, as long as it is elongate. In particular, the elongate susceptor elements may have one of a cylindrical shape or a prolate-ellipsoidal shape. That is, the elongate susceptor elements may have a rod-like shape or a grain-like shape.

As an example, the elongate susceptor elements may be fiber elements, in particular chopped fiber elements or milled fiber elements. As another example, the elongate susceptor elements may be wire elements or thread elements or grain elements or rod elements. Advantageously, the fiber elements or the wire elements or the thread elements or the grain elements or the filament elements or the rod elements are made of a material that is inductively heatable, such as metal fibers, or metal wires or metal threads, are easily available at low cost.

As seen in a plane perpendicular to the length dimension of the elongate susceptor element, a cross-section of the elongate susceptor elements may have a circular shape or an oval shape or an elliptical shape or a triangular shape or a rectangular shape or a quadratic shape or polygonal shape. If the cross-section is circular, the above-mentioned maximum transverse dimension of the elongate susceptor elements corresponds to the diameter of the susceptor elements where it is at maximum along the length dimension of the elongate susceptor elements. If the cross-section is oval or elliptical, the above-mentioned maximum transverse dimension of the susceptor elements corresponds to the length of the semimajor axis of the oval or elliptical cross-section, where it is at maximum along the length dimension of the elongate susceptor elements. If the cross-section is quadratic or in general rectangular, the above-mentioned maximum transverse dimension of the susceptor elements corresponds to the length of the edge/major edge of the quadratic/rectangular cross-section.

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

Accordingly, the elongate susceptor elements may be in general at least one of electrically conductive and either ferromagnetic or ferrimagnetic. In particular, the susceptor material of the elongate susceptor elements may be electrically non-conductive, but either ferromagnetic or ferrimagnetic. Alternatively, the susceptor material of the elongate susceptor elements may be electrically conductive, but neither ferromagnetic nor ferrimagnetic.

Preferably, the susceptor material of the elongate susceptor elements may comprises or consists of a metal, for example ferritic iron, or stainless steel, in particular a grade 410, grade 420, or grade 430 stainless steel; or a ferrimagnetic ceramic.

In addition to the susceptor material, the elongate susceptor elements further comprise a ferromagnetic or ferrimagnetic marker material.

While the susceptor material is optimized with regard to heat loss and thus heating efficiency, the temperature marker material is a magnetic (ferro- or ferrimagnetic) material that is chosen such as to have a Curie temperature which essentially corresponds to a predefined temperature point of the heating process.

The temperature marker material may have a Curie temperature below 500 °C, preferably equal to or below 400 °C, in particular equal to or below 390 °C. For example, the temperature marker material of the elongate susceptor elements may have a Curie temperature in a range between 180 °C and 420 °C, in particular between 210 °C and 380 °C, preferably between 250 °C and 380 °C. Even though the temperature marker material primarily is a functional material providing a temperature marker by its Curie temperature, it may also contribute to the inductive heating process of the susceptor arrangement.

The temperature marker material of the elongate susceptor elements may comprise or may consist of nickel or a nickel alloy.

The susceptor elements may be formed such that the susceptor material is surrounded or covered at least partially, preferably entirely by the temperature marker material.

In addition, the elongate susceptor elements may comprise an outer protective coating surrounding the susceptor material an - if present - the temperature marker material. Preferably, the protective coating makes the elongate susceptor elements resistant to external influences, especially corrosive influences.

The provided elongate susceptor elements may have substantially identical characteristics such as susceptor material, maximum extent, form ratio, temperature marker material, outer coating etc. Alternatively, a mixture of elongate susceptor elements with different characteristics may be provided.

It is also possible that the susceptor material of the susceptor elements itself has a temperature marker function. That is, the elongate susceptor elements may comprise a single material which acts both as a susceptor material and as a temperature marker material.

The present disclosure also relates to an apparatus for applying elongate susceptor elements to an aerosol-forming substrate. The apparatus may be in particular suited for use in a method according to the present disclosure. Therefore, the above description applies accordingly to the apparatus according to the present disclosure.

The apparatus may comprise a screening device, the screening device itself comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes.

The elongate susceptor elements may be preferably provided via a susceptor supply. The susceptor supply may be in particular a hopper. The susceptor supply may be coupled to the screening device for providing and feeding elongate susceptor elements.

The aerosol-forming substrate in the form a sheet material may be preferably provided via a substrate supply to or past the screen, either continuously or stepwise. The sheet material may be in particular provided vertically below screen, enabling to deposit the at least partially aligned elongate susceptor elements discharged from screen on the main surface of the sheet material, preferably under the influence of gravity. As used herein, the term “to or past the screen” is understood as downstream side of the screen, that is, that side of the screen, where the susceptor elements exit the screen upon having passed through the elongate screen openings.

The substrate supply may preferably comprise a conveyor belt or one or more rollers for providing the aerosol-forming substrate in the form the sheet material past screen in a conveying direction, either continuously or stepwise. The conveying direction may be preferably parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition.

For providing optimal deposition of the elongate susceptor elements on the sheet material, the screen may be preferably configured and arranged such that a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition is substantially parallel to the conveying direction.

The screening device may be preferably configured such that the screen is movable relative to (in particular across) the sheet material in a direction transverse, preferably perpendicular to the conveying direction.

To further improve deposition of the elongate susceptor elements on a large surface area of the sheet material, the screening device may be in particular configured such that screen is movable relative to (in particular across) the sheet material in a plane parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition. Movement may be preferably in a direction transverse to the alignment axis of the screen and/or in a direction parallel to the alignment axis of the screen or parallel to a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition.

The screen may be, in a preferred configuration, arranged horizontally or inclined along the alignment axis with respect to the horizontal, in particular by an angle of inclination in a range between 2 degrees and 45 degrees, preferably between 2 degrees and 20 degrees, more preferably between 5 degrees and 10 degrees.

A maximum lateral dimension of the elongate screen openings perpendicular to their longitudinal axis may be in a range between 0.5 and 1.5, in particular between 0.75 and 1.25, preferably between 0.9 and 1.1 times a mean length dimension of the elongate susceptor elements.

A maximum lateral dimension of elongate screen openings perpendicular to their longitudinal axis may be in a range between 0.1 millimeter and 20 millimeter, in particular 0.25 millimeter and 10 millimeter, preferably between 0.5 millimeter and 5 millimeter.

The screening device may be, in a preferred configuration, a vibrating screening device, wherein the screen may be a vibrating screen.

The screening device may in particular comprise a vibration generator configured to vibrate the screen. Preferably, the vibration generator may be an ultrasonic vibration generator.

The screening device may further comprise a brushing member which is movable relative to the screen across an upstream side of the screen, the brushing member being configured to assist the elongated susceptor elements to pass through the elongate screen openings.

A lateral dimension of the screen may preferably substantially correspond to a lateral dimension of the sheet material.

As used herein, the term "aerosol-generating article" refers to an article comprising at least one aerosol-forming substrate that is capable of releasing volatile compounds when heated in order to form an aerosol. The aerosol-generating article may be a consumable, in particular a consumable to be discarded after a single use. For example, the article may be an elongate article or a rod-shaped article. The elongate or rod-shaped article may have a shape resembling the shape of conventional cigarettes. In particular, such an article may have a circular or elliptical or oval or square or rectangular or triangular or a polygonal cross-section. As another example, the article may be a cartridge including a liquid aerosol-forming substrate to be heated.

As used herein, the term "aerosol-forming substrate" denotes a substrate formed from or comprising an aerosol-forming material that is capable of releasing volatile compounds upon heating in order to generate an aerosol. Preferably, the aerosol-forming substrate is intended to be heated rather than combusted in order to release the aerosol-forming volatile compounds. Accordingly, such a substrate may be denoted as a heat-not-burn aerosol-forming substrate. Likewise, an aerosol-generating article comprising such an aerosol-forming substrate may be denoted as a heat-not-burn aerosol-generating article.

In general, the aerosol-forming substrate may comprise at least one aerosol former and at least one sensorial material both of which are volatilizable when heated. The sensorial material may comprise at least one of a tobacco-containing material, a nicotine-containing material and a flavoring substance. Examples of suitable aerosol formers are glycerin and propylene glycol. Examples of flavoring substance may be plant extracts and natural or artificial flavors.

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

As mentioned above, the aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the substrate upon heating. In particular, the aerosol-forming substrate may comprise reconstituted tobacco material or a tobacco-containing slurry. Accordingly, 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 flavourants.

The aerosol-forming substrate may also be a paste-like material, a sachet of porous material comprising aerosol-forming substrate, or, for example, loose tobacco mixed with a gelling agent or sticky agent, which could include a common aerosol former such as glycerin, and which is compressed or molded into a plug. The aerosol-forming substrate is made from a sheet material. For example, the aerosolforming substrate may be made from a crimped tobacco sheet comprising a tobacco material, organic fibers, a binder, an aerosol former. Alternatively, the aerosol-forming substrate may be made from a sheet material including a nicotine-containing material, organic fibers, a binder, an aerosol former. As yet another alternative, the aerosol-forming substrate may be made from a sheet material containing tobacco cut filler. To this extent, it has been found that the aerosolgenerating article is easy to manufacture, especially with respect to a preferred alignment of the elongate susceptor elements relative to a pre-defined reference axis of the article, if the susceptor elements are applied to the aerosol-forming substrate when it is in the form of a sheet material. This may be the result of a manufacturing process including the deposition of the susceptor elements on an outer surface of a sheet material, either during a primary process, in which the sheet material is produced, or during a secondary process, where the sheet material is machined and combined with other semi-finished goods to obtain the final product. As a result of this, the elongate susceptor elements may be finally disposed on an outer surface of the sheet material or at least partially embedded in the sheet material close to an outer surface of the sheet material. This can be observed even if the sheet material is subsequently machined, for example, crimped and gathered such as to form a substrate plug in the final article.

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.

Example Ex1 : A method of applying elongated susceptor elements 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 a sheet material; providing elongated susceptor elements; suppling the elongate susceptor elements to and passing them through a screening device comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes; depositing the elongated susceptor elements, which are discharged from the screen in at least partially alignment, on a main surface of the sheet material, preferably under the influence of gravity.

Example Ex2: The method according to example Ex1 , wherein the at least partial alignment is such that an angle between a length dimension of the elongated susceptor elements and the alignment axis of the screen is in a range between +30 degrees and -30 degrees, preferably between +25 degrees and -25 degrees, in particular between +10 degrees and -10 degrees.

Example Ex3: The method according to example Ex1 , wherein the elongated susceptor elements being discharged from the screen are aligned substantially parallel to the alignment axis of the screen. Example Ex4: The method according to any one of the preceding examples, wherein the screen is arranged vertically above the sheet material at a place of deposition on the main surface.

Example Ex5: The method according to any one of the preceding examples, wherein during depositing the elongated susceptor elements on the main surface of the sheet material, the screen and the sheet material are moved relative to each other.

Example Ex6: The method according to any one of the preceding examples, wherein during depositing the elongated susceptor elements on the main surface of the sheet material, the sheet material is moved relative (in particular past) to the screen in a conveying direction, the conveying direction preferably being parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition.

Example Ex7: The method according to example Ex6, wherein a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition is substantially parallel to the conveying direction.

Example Ex8: The method according to any one of examples Ex6 or Ex7, wherein the alignment axis of the screen is substantially parallel to the conveying direction.

Example Ex9: The method according to any one of examples Ex6 to Ex8, wherein the sheet material is moved relative to (in particular past) the screen in the conveying direction by means of a conveyor belt or by means of one or more rollers.

Example Ex10: The method according to any one of examples Ex6 to Ex9, wherein during depositing the elongated susceptor elements on the main surface of the sheet material, the screen is moved relative to (in particular across) the sheet material in a direction transverse, preferably perpendicular to the conveying direction.

Example Ex11 : The method according to any one of the preceding examples, wherein during depositing the elongated susceptor elements on the main surface of the sheet material, the screen is moved relative to (in particular across) the sheet material in a plane parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition, especially in a direction transverse to the alignment axis of the screen and/or in a direction parallel to the alignment axis of the screen or parallel to a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition.

Example Ex12: The method according to any one of the preceding examples, wherein the screen is arranged horizontally or inclined along the alignment axis with respect to the horizontal, in particular by an angle of inclination in a range between 2 degrees and 45 degrees, preferably between 2 degrees and 20 degrees, more preferably between 5 degrees and 10 degrees.

Example Ex13: The method according to any one of the preceding examples, wherein a maximum lateral dimension of the elongate screen openings perpendicular to their longitudinal axis is in a range between 0.5 and 1.5, in particular between 0.75 and 1.25, preferably between 0.9 and 1.1 times a mean length dimension of the elongated susceptor elements.

Example Ex14: The method according to any one of the preceding examples, wherein a cross-section of the elongate screen openings has a rectangular shape or an elliptical shape or an obround shape.

Example Ex15: The method according to any one of the preceding examples, wherein a maximum lateral dimension of the elongate screen openings perpendicular to the longitudinal axis is in a range between 0.1 millimeter and 20 millimeter, in particular 0.25 millimeter and 10 millimeter, preferably between 0.5 millimeter and 5 millimeter.

Example Ex16: The method according to any one of the preceding examples, wherein the screening device is a vibrating screening device and the screen is a vibrating screen.

Example Ex17: The method according to any one of the preceding examples, wherein the screening device comprises a vibration generator, preferably an ultrasonic vibration generator, configured to vibrate the screen.

Example Ex18: The method according to any one of the preceding examples, wherein the screening device comprises a brushing member which is movable relative to the screen across an upstream side of the screen and configured to assist the elongated susceptor elements to pass through the elongate screen openings.

Example Ex19: The method according to any one of the preceding examples, wherein a lateral dimension of the screen perpendicular to the alignment axis substantially corresponds to a lateral dimension of the sheet material.

Example Ex20: The method according to any one of the preceding examples, wherein the aerosol-forming substrate is made from a substrate slurry casted into the form of the sheet material, wherein the elongated susceptor elements are deposited on the casted substrate slurry.

Example Ex21 : The method according to example Ex20, wherein the elongated susceptor elements are deposited on the main surface of the sheet material prior to drying the casted substrate slurry.

Example Ex22: The method according to any one of the preceding examples, wherein the aerosol-forming substrate in the form of the sheet material is a continuous substrate sheet.

Example Ex23: The method according to example Ex22, wherein the elongated susceptor elements are deposited on the main surface of the sheet material during or after crimping the continuous substrate sheet, especially during or after crimping the continuous substrate sheet in a longitudinal direction, in particular in a machine direction of the continuous substrate sheet.

Example Ex24: The method according to any one of the preceding examples, wherein a sticky agent is applied to the sheet material prior to depositing the elongate susceptor elements thereon. Example Ex25: The method according to example Ex24, wherein the sticky agent comprises glycerol.

Example Ex26: The method according to any one of the preceding examples, wherein a ratio of a length dimension to a maximum transverse dimension of the elongated susceptor elements is greater than 4, in particular greater than 10, preferably greater than 20, more preferably greater than 25, even more preferably greater than 30, most preferably greater than 35.

Example Ex27: The method according to any one of the preceding examples, wherein a ratio of the length dimension to a maximum transverse dimension of the elongated susceptor elements is in a range between 4 and 500, in particular between 10 and 300, preferably between 20 and 200, more preferably between 30 and 100.

Example Ex28: The method according to any one of the preceding examples, wherein a length dimension of the elongated susceptor elements is in a range between 20 micrometer and 50 millimeter, in particular 100 micrometer and 16 millimeter, preferably between 0.5 millimeter and 5 millimeter

Example Ex29: The method according to any one of the preceding examples, wherein a maximum transverse dimension of the elongated susceptor elements is a range between 5 micrometer and 500 micrometer, in particular 10 micrometer and 150 micrometer, preferably 80 micrometer and 120 micrometer.

Example Ex30: The method according to any one of the preceding examples, wherein a maximum transverse dimension of the elongated susceptor elements is equal to or smaller than 500 micrometer, in particular 100 micrometer, preferably 50 micrometer, more preferably 25 micrometer.

Example Ex31 : The method according to any one of the preceding examples, wherein the elongated susceptor elements have one of a cylindrical shape or a prolate-ellipsoidal shape.

Example Ex32: The method according to any one of the preceding examples, wherein the elongated susceptor elements are one of fiber elements, in particular chopped fiber elements or milled fiber elements, or wire elements, or thread elements, or grain elements or rod elements.

Example Ex33: The method according to any one of the preceding examples, wherein a cross-section of the elongated susceptor elements in a plane perpendicular to the length dimension of the susceptor element has a circular shape or an oval shape or an elliptical shape or a triangular shape or a rectangular shape or a quadratic shape or polygonal shape.

Example Ex34: The method according to any one of the preceding examples, wherein the elongated susceptor elements comprise a susceptor material which is at least one of electrically conductive and either ferromagnetic or ferrimagnetic.

Example Ex35: The method according to example Ex34, wherein the susceptor material of the elongated susceptor elements comprises or consists of a metal, for example ferritic iron, or stainless steel, in particular a grade 410, grade 420, or grade 430 stainless steel; or a ferrimagnetic ceramic.

Example Ex36: The method according to any one examples Ex34 or Ex35, wherein the elongated susceptor elements further comprise a ferromagnetic or ferrimagnetic temperature marker material in addition to the susceptor material.

Example Ex37: The method according to example Ex36, wherein the temperature marker material of the elongated susceptor elements comprises or consists of nickel or a nickel alloy.

Example Ex38: An apparatus for applying elongated susceptor elements to an aerosolforming substrate, in particular for use in a method according to any one of the preceding claims, the apparatus comprising a screening device comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes.

Example Ex39: The apparatus according to example Ex38, further comprising a susceptor supply, in particular a hopper, coupled to the screening device for providing and feeding to the screening device.

Example Ex40: The apparatus according to any one of examples Ex38 or Ex39, further comprising a substrate supply for providing an aerosol-forming substrate in the form a sheet material to or past the screen (downstream side of the screen), in particular vertically below the screen (downstream side of the screen), enabling to deposit the elongated susceptor elements, being discharged from the screen in at least partially alignment, on a main surface of the sheet material, preferably under the influence of gravity.

Example Ex41 : The apparatus according to example Ex40, wherein the substrate supply comprises a conveyor belt or one or more rollers for providing the aerosol-forming substrate in the form the sheet material past the screen (downstream side of the screen) in a conveying direction, the conveying direction preferably being parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition.

Example Ex42: The apparatus according to example Ex41 , wherein the screen is configured and arranged such that a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition is substantially parallel to the conveying direction, in particular such that the alignment axis of the screen is substantially parallel to the conveying direction.

Example Ex43: The apparatus according to any one of example Ex41 or Ex42, wherein the screening device is configured such that the screen is movable relative to (in particular across) the sheet material in a direction transverse, preferably perpendicular to the conveying direction.

Example Ex44: The apparatus according to any one of examples Ex38 to Ex43, wherein the screening device is configured such that the screen is movable relative to (in particular across) the sheet material in a plane parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition, especially in a direction transverse to the alignment axis of the screen and/or in a direction parallel to the alignment axis of the screen or parallel to a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition.

Example Ex45: The apparatus according to any one of examples Ex38 to Ex44, wherein the screen is arranged horizontally or inclined along the alignment axis with respect to the horizontal, in particular by an angle of inclination in a range between 2 degrees and 45 degrees, preferably between 2 degrees and 20 degrees, more preferably between 5 degrees and 10 degrees.

Example Ex46: The apparatus according to any one of examples Ex38 to Ex45, wherein a maximum lateral dimension of the elongate screen openings perpendicular to their longitudinal axis is in a range between 0.5 and 1.5, in particular between 0.75 and 1.25, preferably between 0.9 and 1.1 times a mean length dimension of the elongated susceptor elements.

Example Ex47: The apparatus according to any one of examples Ex38 to Ex46, wherein a maximum lateral dimension of the elongate screen openings perpendicular to the longitudinal axis is in a range between 0.1 millimeter and 20 millimeter, in particular 0.25 millimeter and 10 millimeter, preferably between 0.5 millimeter and 5 millimeter.

Example Ex48: The apparatus according to any one of examples Ex38 to Ex47, wherein the screening device is a vibrating screening device and the screen is a vibrating screen.

Example Ex49: The apparatus according to any one of examples Ex38 to Ex48, wherein the screening device comprises a vibration generator, preferably an ultrasonic vibration generator, configured to vibrate the screen.

Example Ex50: The apparatus according to any one of examples Ex38 to Ex49, wherein the screening device comprises a brushing member which is movable relative to the screen across an upstream side of the screen and configured to assist the elongated susceptor elements to pass through the elongate screen openings.

Example Ex51 : The apparatus according to any one of examples Ex38 to Ex50, wherein a lateral dimension of the screen perpendicular to the alignment axis substantially corresponds to a lateral dimension of the sheet material.

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

Figure 1A schematically shows a screening device in top view according to the present invention;

Figure 1 B schematically shows a detail of substantially parallel aligned susceptor elements;

Figure 1C schematically shows a detail of partially aligned susceptor elements;

Figure 2 schematically shows a top view of an apparatus according to an embodiment of the present invention; Figure 3 schematically shows a top view of an apparatus according to another embodiment of the present invention;

Figure 4 schematically shows a side view of an apparatus according to an embodiment of the present invention;

Figure 5 schematically shows a side view of an apparatus according to another embodiment of the present invention;

Figure 6 schematically shows a flow chart of a method according to the present invention; and

Figure 7 schematically shows and in detail a substrate element comprising elongated susceptor elements.

All the examples shown in the figures are schematic and not to scale.

In Fig. 1A, an example of a screening device 1 is shown schematically in a top view. A hopper 2 is arranged upstream of the screening device 1 to provide elongate susceptor elements 3 to a screen 4. The screen 4 comprises a plurality of elongate screen openings 5, of which only three are provided with reference numerals. The elongate screen openings 5 are arranged in parallel along an alignment axis D of the screen 4. The screen 4 is preferably vibrated and as a consequence, the elongate susceptor elements 3 provided are passed through the elongate screen openings 5 of the screen 4 and discharged from the screen. The screen openings 5 are arranged and configured such that the elongate susceptor elements 3 provided are passed through the screen openings in at least partial alignment. The elongate screen openings 5 have a rectangular cross-section, but may be also provided with a different shape, for example an elliptical shape or an obround shape, depending on the shape of the elongate susceptor elements 3.

In the example shown in Fig. 1 B, the elongate susceptor elements 3 are discharged in a substantially parallel alignment to each other and to the alignment axis D of the screen 4 on a main surface of an aerosol forming substrate provided as a sheet material. In this case, the elongate susceptor elements 3 may be also deposited substantially parallel to a projection of the longitudinal direction D onto a plane defined by the sheet material or onto a plane tangent to the sheet material at a place of deposition.

Alternatively, as shown in the detail of Fig. 1 C, the elongate susceptor elements 3 may be discharged in at least partial alignment, wherein an angle alpha (a) between a length dimension, of the elongated susceptor elements 3 and the alignment axis D is in a range between +30 degrees and -30 degrees, in particular +25 degrees and -25 degrees, preferably between +10 degrees and -10 degrees, and deposited on a main surface of an aerosol-forming substrate provided as a sheet material. Accordingly, the elongate susceptor elements 3 may be discharged and deposited in a least partial alignment to a projection of the alignment axis D onto a plane defined by the sheet material or onto a plane tangent to the sheet material at a place of deposition. In this case, the angle alpha (a) is the angle between a length dimension of the elongated susceptor elements 3 and the projection of the alignment axis onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition.

Fig. 2 schematically shows an apparatus 9 according to the present invention in top view. The apparatus 9 comprises screening device 1 comprising a screen 4 fed by a hopper 2, as shown in Fig. 1 , mounted on a beam 13. The screen is provided with a plurality of elongate screen openings 5. An aerosol-forming substrate 14 is provided in the form of a sheet material 15 to the apparatus 9 below the screening device 1 and may be conveyed past the screening device 1 in a conveying direction C. The conveying direction C in the example of Fig.2 is parallel to a plane defined by the sheet material 15 (corresponding to the drawing plane). A projection of the alignment axis D onto the plane defined by the sheet material 15 is also parallel to the conveying direction C. The screening device 1 is movably mounted on the beam 13 and is moved transversely across the sheet material 15 in a transverse direction T perpendicular to the conveying direction C, schematically denoted by the double-arrow. The sheet material 15 may be a continuous substrate sheet, as schematically shown in Fig. 2, or a finite substrate sheet. The sheet material 15 may be conveyed in the conveying direction C past the screening device 1 continuously or stepwise. The movement of the screening device 1 along the transverse direction T allows for the deposition of the elongate susceptor elements 3 over the whole width of the sheet (which lies in the drawing plane and is perpendicular to the conveying direction C) with a reduced amount of screening devices 1. As an example, one screening device 1 as shown in Fig. 2 may be provided, wherein the screening device 1 moves along the transverse direction T over the whole width of the sheet material 15 and is configured for depositing the elongate susceptor elements 3 over the whole width of the sheet material 15. Alternatively, two or more screening devices 1 may be provided mounted on the beam 13, each of the screening devices 1 being movable along the transverse direction T and configured for depositing the elongate susceptor elements 3 on a respective width portion of the sheet material 15. The elongate susceptor elements 3 are passed thorough the elongate screen openings 5 and deposited on a main surface of the sheet material 15 in at least partial alignment as shown in Fig. 1 A, 1 B and 1 C.

Fig. 3 shows another example of an apparatus 29 according to the present invention in top view. The apparatus 29 comprises a screening device 1 comprising a screen 4 mounted on the beam 13. In the example shown in Fig. 3, the screen 4 has a lateral dimension corresponding to the lateral dimension of the sheet material 15, that means, that the screen covers the whole width of the sheet material 15. An aerosol-forming substrate 14 is provided in the form of a sheet material 15 to the apparatus 29 below the screening device 1 and may be conveyed past the screening device 1 in a conveying direction C. The conveying direction C in the example of Fig.3 is parallel to a plane defined by the sheet material 15 (corresponding to the drawing plane). A projection of the alignment axis D onto the plane defined by the sheet material 15 is also parallel to the conveying direction C. The sheet material 15 may be a continuous substrate sheet, as schematically shown in Fig. 3, or a finite substrate sheet. The sheet material 15 may be conveyed in the conveying direction C past the screening device 1 continuously or stepwise. Providing screen 4 with a lateral dimension corresponding to the lateral dimension of the sheet material 15, as shown in Fig. 3, allows for the deposition of the elongate susceptor elements 3 over the whole width of the sheet material 15 without the need of providing movement of the screening device 1 as shown in Fig. 2. Such a combination is however possible. The elongate susceptor elements 3 are therefore conveyed towards the discharge ends 5 of the guide channels 4 in at least a partial alignment and deposited on a main surface of the sheet material 15 in at least partial alignment as shown in Fig. 1A and 1 B.

Additionally or alternatively, the beam 13 may be moved relative to the sheet material 15. In the examples shown in Figs. 2 and 3, the beam 13 may be moved in a beam direction parallel to the conveying direction C, even in the case where the sheet material 15 is not conveyed, as shown schematically by the double arrow B.

In Fig. 4, a schematic, simplified lateral view of an apparatus according to the present invention is shown. The apparatus of Fig. 4 may be constructed according to the apparatuses 9 and 29 of Figs 2 and 3. The at least one screening device 1 is arranged above the sheet material 15 on the beam 13. The sheet material 15 is conveyed in the conveying direction C parallel to a plane defined by the sheet material 15. The sheet material 15 may be conveyed by means or one or more rollers 17 and/or one or more conveyor belts 18 in the conveying direction C, either continuously or stepwise. The screen 4 of the screening device 1 is arranged at an angle 20 between the alignment axis D and the plane of the sheet material 15, corresponding to a horizontal plane. Preferably, the angle 20 is in a range between 2 degrees and 45 degrees, more preferred between 2 and 20 degrees, and even more preferred between 5 degrees and 20 degrees.

In Fig. 5, a schematic, simplified lateral view of an apparatus according to the present invention is shown. The apparatus of Fig. 6 may be constructed according to the apparatuses 9 and 29 of Figs 2 and 3. The screen 4 of the screening device 1 is arranged horizontally and parallel to the plane defined by the sheet material 15.

In Fig. 6, a flow chart of a method according to the present invention is shown. The method of applying elongate susceptor elements 3 to an aerosol-forming substrate 14 for use in an inductively heatable aerosol-generating article according to the present invention may be performed with an apparatus according to the present invention, as described above. In a first step 23, an aerosol-forming substrate 14 is provided in the form of a sheet material 15. In a second step 24, elongate susceptor elements 3 are provided. In a subsequent step 25, the elongate susceptor elements 3 provided in step 24 are then supplied to a screening device 1 comprising a screen 4. The screen 4 is provided with a plurality of elongate screen openings 5 arranged in parallel along the alignment axis D of the screen 4, where the elongate susceptor elements 3 are passed through the elongate screen openings 5. In step 26, the elongate susceptor elements 3 are discharged from the screen 4 in at least partial alignment 4 on a main surface of the sheet material 15, in particular under the influence of gravity.

Fig. 7 shows a perspective view of a portion of a substrate element 110 forming part of a rod-shaped aerosol-generating article, including a detailed view (bottom right) of its inner structure, in particular the structure of aerosol-forming substrate 14 and the elongate susceptor elements 3. As can be seen from both, the perspective view and the detailed view, the aerosolforming substrate 14 is made from a sheet material 15 that has been gathered into the cylindrical shape of the substrate element 110 upon having deposited elongate susceptor elements thereon. For example, the aerosol-forming substrate 14 may be made from a crimped tobacco sheet comprising a tobacco material, organic fibers, a binder, an aerosol. As can be further seen from the detailed view, the elongate susceptor elements 3 are deposited on the main surface of the sheet material 15 which can be still observed even though the sheet material 15 is crimped and gathered. This may be the result of a manufacturing process including the deposition of the susceptor elements 3 on a main surface of the sheet material 15 according to the present invention, either during a primary process, in which the sheet material 15 is produced, or during a secondary process, where the sheet material 15 is machined. The elongate susceptor elements 3 within the substrate element 110 are all aligned along their length dimension (predominant dimension) substantially in parallel with a pre-defined reference axis of the aerosol-generating article, here the length axis 101 of the article, which is chosen such that in use it coincides with the orientation M of the field lines of an alternating magnetic field used to inductively heat the elongate susceptor elements 3, for example when the aerosol-generating article is engaged with an aerosol-generating device providing the alternating magnetic field. As mentioned before, the heating efficiency is at maximum if the elongate susceptor elements 3 are all aligned in parallel to the orientation M of the alternating magnetic field.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1 . A method of applying elongated susceptor elements 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 a sheet material;

- providing elongated susceptor elements;

- suppling the elongate susceptor elements to and passing them through a screening device comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes;

- depositing the elongated susceptor elements, which are discharged from the screen in at least partially alignment, on a main surface of the sheet material, preferably under the influence of gravity.

2. The method according to claim 1 , wherein the at least partial alignment is such that an angle between a length dimension of the elongated susceptor elements and the alignment axis of the screen is in a range between +30 degrees and -30 degrees, preferably between +25 degrees and -25 degrees, in particular between +10 degrees and -10 degrees.

3. The method according to claim 1 , wherein the elongated susceptor elements being discharged from the screen are aligned substantially parallel to the alignment axis of the screen.

4. The method according to any one of the preceding claims, wherein during depositing the elongated susceptor elements on the main surface of the sheet material, the sheet material is moved relative (in particular past) to the screen in a conveying direction, the conveying direction preferably being parallel to a plane defined by the sheet material or parallel to a plane tangent to the sheet material at a place of deposition.

5. The method according to claim 4, wherein a projection of the alignment axis of the screen onto the plane defined by the sheet material or onto the plane tangent to the sheet material at the place of deposition is substantially parallel to the conveying direction.

6. The method according to any one of the preceding claims, wherein the aerosol-forming substrate is made from a substrate slurry casted into the form of the sheet material, wherein the elongated susceptor elements are deposited on the casted substrate slurry.

7. The method according to claim 6, wherein the elongated susceptor elements are deposited on the main surface of the sheet material prior to drying the casted substrate slurry.

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

9. The method according to any one of claims 1 to 5, wherein the aerosol-forming substrate in the form of the sheet material is a continuous substrate sheet and wherein the elongated susceptor elements are deposited on the main surface of the sheet material during or after crimping the continuous substrate sheet, especially during or after crimping the continuous substrate sheet in a longitudinal direction, in particular in a machine direction of the continuous substrate sheet.

10. The method according to any one of the preceding claims, wherein a ratio of a length dimension to a maximum transverse dimension of the elongated susceptor elements is greater than 4, in particular greater than 10, preferably greater than 20, more preferably greater than 25, even more preferably greater than 30, most preferably greater than 35.

11. The method according to any one of the preceding claims, wherein a ratio of the length dimension to a maximum transverse dimension of the elongated susceptor elements is in a range between 4 and 500, in particular between 10 and 300, preferably between 20 and 200, more preferably between 30 and 100.

12. The method according to any one of the preceding claims, wherein a length dimension of the elongated susceptor elements is in a range between 20 micrometer and 50 millimeter, in particular 100 micrometer and 16 millimeter, preferably between 0.5 millimeter and 5 millimeter.

13. The method according to any one of the preceding claims, wherein a maximum transverse dimension of the elongated susceptor elements is a range between 5 micrometer and 500 micrometer, in particular 10 micrometer and 150 micrometer, preferably 80 micrometer and 120 micrometer.

14. The method according to any one of the preceding claims, wherein a maximum transverse dimension of the elongated susceptor elements is equal to or smaller than 500 micrometer, in particular 100 micrometer, preferably 50 micrometer, more preferably 25 micrometer.

15. An apparatus for applying elongated susceptor elements to an aerosol-forming substrate, in particular for use in a method according to any one of the preceding claims, the apparatus comprising an aerosol-generating substrate supply, an elongated susceptor supply and a screening device comprising a screen having a plurality of elongate screen openings arranged in parallel along an alignment axis of the screen with respect to their longitudinal axes.