WO2025056570A1

WO2025056570A1 - Aerosol-generating article with coated filter wrapper

Info

Publication number: WO2025056570A1
Application number: PCT/EP2024/075297
Authority: WO
Inventors: Stefan Catalin IVASCU; Piotr JAROS
Original assignee: Philip Morris Products S.A.
Priority date: 2023-09-12
Filing date: 2024-09-11
Publication date: 2025-03-20

Abstract

The invention relates to an aerosol-generating article comprising a substrate portion comprising aerosol-forming substrate. The aerosol-generating article further comprises a filter element. The filter element comprises cellulosic filtration material. The filter element comprises a filter wrapper wrapped around the cellulosic filtration material. The filter wrapper has a grammage of 50 gsm to 120 gsm. The filter wrapper comprises a fluid impermeable coating. The invention further relates to a method for forming a filter element of the aerosol-generating article.

Description

AEROSOL-GENERATING ARTICLE WITH COATED FILTER WRAPPER

The present invention relates to an aerosol-generating article. The invention further relates to a method for forming a filter element of the aerosol-generating article.

It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate are volatilised without burning the aerosolforming substrate. Aerosol-forming substrate may be provided as part of an aerosol-generating article. The aerosol-generating article may have a rod shape for insertion of the aerosolgenerating article into a cavity, such as a heating chamber, of the aerosol-generating device. A heating element may be arranged in or around the heating chamber for heating the aerosolforming substrate once the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device. Increasingly, there is desired to improve sustainability of aerosol-generating articles. Particularly, the materials traditionally used in filters of aerosolgenerating articles may be suboptimal from a sustainability perspective.

It would be desirable to have an aerosol-generating article with improved sustainability. It would be desirable to have a filter element of an aerosol-generating article with improved sustainability. It would be desirable to have a filter material of a filter element of an aerosolgenerating article with improved sustainability. It would be desirable to have a filter wrapper of a filter element of an aerosol-generating article with improved sustainability. It would be desirable to have a filter wrapper of a filter element of an aerosol-generating article with improved visual properties.

According to an embodiment of the invention there is provided an aerosol-generating article that may comprise a substrate portion comprising aerosol-forming substrate. The aerosol-generating article may further comprise a filter element. The filter element may comprise cellulosic filtration material. The filter element may comprise a filter wrapper wrapped around the cellulosic filtration material. The filter wrapper may have a grammage of 50 gsm to 120 gsm. The filter wrapper comprises a fluid impermeable coating.

The filter wrapper may have a grammage of 60 gsm to 100 gsm. The filter wrapper comprises a fluid impermeable coating. The filter wrapper may have a grammage of 70 gsm to 90 gsm.

According to an embodiment of the invention there is provided an aerosol-generating article comprising a substrate portion comprising aerosol-forming substrate. The aerosol- generating article further comprises a filter element. The filter element comprises cellulosic filtration material. The filter element comprises a filter wrapper wrapped around the cellulosic filtration material. The filter wrapper has a grammage of 50 gsm to 120 gsm. The filter wrapper comprises a fluid impermeable coating.

Using cellulosic filtration material in the filter element may improve sustainability of the filter element. Particularly, previously used cellulose acetate may be undesired from a sustainability perspective. Cellulosic filtration material may be a sustainable alternative to cellulose acetate.

The filter wrapper may also be denoted as plug wrap or plug wrapper.

In this specification, the unit of measurement for basis weight, gram(s) per square meter, is abbreviated as “gsm”. The grammage of the filter wrapper (of 50 gsm to 120 gsm) may be without the fluid impermeable coating. The fluid impermeable coating may add between 1 gsm to 2 gsm to the grammage of the filter wrapper after application.

The filter element may also be denoted as filter plug.

The cellulosic filtration material may be the only filtration material employed in the aerosol-generating article. Our words, the aerosol-generating article may be free of filtration materials that are not cellulosic filtration material.

The substrate portion may be arranged upstream of the filter element. The aerosolforming substrate of the substrate portion may be wrapped in a substrate wrapper.

Between the substrate portion and the filter element, a cooling portion may be arranged. The cooling portion may be tubular and hollow. Perforations may be arranged in a sidewall of the cooling portion to allow airflow of ambient air into the cooling portion. The cooling portion may be made from cardboard.

One or more of the substrate portion, the cooling portion and the filter element may be attached to each other via a tipping paper.

The fluid impermeable coating may prevent fluid. Particularly, liquid components of the filter element may be prevented from soaking into the filter wrapper. Soaking of liquid components into the filter wrapper may negatively impair the visual appearance of the filter wrapper and potentially lead to a soggy filter wrapper. Particularly, a liquid additive as described in more detail below is prevented from reaching the filter wrapper due to the fluid impermeable coating.

The cellulosic filtration material may be free of cellulose acetate. The cellulosic filtration material may comprise a paper material. The cellulosic filtration material may comprise a nonwoven paper material.

The cellulosic filtration material may comprise a fibrous material comprising a plurality of regenerated cellulose fibres. The regenerated cellulose fibres may be one or more of viscose fibres, modal fibres, Lyocell fibres and viscose rayon fibres.

The cellulosic filtration material may comprise a fibrous material comprising a plurality of natural fibres. The natural fibres may be one or more of flax fibres, hemp fibres, jute fibres, kenaf fibres, ramie fibres, abaca fibres, phormium fibres, sisal fibres, coir fibres, cotton fibres, and kapok fibres.

The filter wrapper may have a grammage of 60 gsm to 110 gsm. The filter wrapper may have a grammage of 70 gsm to 100 gsm.

The cellulosic filtration material may comprise an additive. The additive may be a phenol scavenger. The additive may comprise triethyl citrate, preferably liquid triethyl citrate.

The cellulosic filtration material may comprise, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% triethyl citrate.

The cellulosic filtration material may comprise, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% polyethylene glycol. The cellulosic filtration material may comprise, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% low molecular weight polyethylene glycol.

The polyethylene glycol (PEG) may act as a phenol scavenger. It has surprisingly be found that polyethylene glycol is particularly preferred as a phenol scavenger. Particularly, it has surprisingly be found that polyethylene glycol has a phenol adsorption higher than other additives. Further, it has surprisingly be found that polyethylene glycol has a lesser tendency in comparison to other additives to migrate into other components of the aerosol-generating article, particularly abutting portions of the aerosol-generating article. Particularly advantageous is to use a low molecular weight polyethylene glycol, particularly preferred having a weight average molecular weight M_w of between 300 and 500, more preferably of between 350 and 450, most preferably of 400.

The cellulosic filtration material may comprise, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% triacetin.

The additive may be provided as a liquid additive. Alternatively, the additive may be provided as a gel-like additive. The fluid impermeable coating may be provided only on one side of the filter wrapper.

The fluid impermeable coating may be provided on the side of the filter wrapper facing the cellulosic filtration material.

Providing the fluid impermeable coating on the side of the filter wrapper facing the cellulosic filtration material may prevent liquid components of the filter element, particularly a liquid additive added to the cellulosic filtration material, to permeate into the filter wrapper.

The fluid impermeable coating may be provided on both sides of the filter wrapper.

Providing the fluid impermeable coating on both sides of the filter wrapper may prevent a staining of the filter wrapper both from the side of the cellulosic filtration material as well as from the outside.

The fluid impermeable coating may be coated onto the filter wrapper via rotogravure printing or flexo printing.

The fluid impermeable coating may comprise cellulose derivatives, preferably one or more of ethyl cellulose, microfibrillated cellulose and carboxymethyl cellulose.

The fluid impermeable coating may comprise fluorinated coatings.

Fluorinated coatings may particularly effectively prevent fluid from soaking into the filter wrapper.

The fluid impermeable coating may comprise one or more of: an acrylate, a styrene, a butadiene, a starch, a starch derivative, a cellulose derivative, an alginate, a polyvinyl alcohol, a polyvinyl acetate, polyfluoroalkyl, a gelatin, bio-wax and a gum.

The fluid impermeable coating may be configured as a hardness-enhancing coating.

Increasing hardness of the filter wrapper by means of the fluid impermeable coating may increase the overall hardness of the filter element. An increased hardness of the filter element may be beneficial when the filter element is held between fingers or lips of a user due to preventing unwanted deformation of the filter element.

The invention further relates to a method for forming a filter element of the aerosolgenerating article, comprising: providing cellulosic filtration material, providing a filter wrapper, wherein the filter wrapper has a grammage of 50 gsm to 120 gsm, coating the filter wrapper with a fluid impermeable coating, and wrapping the filter wrapper around the cellulosic filtration material.

As used herein, the term “phenols” refers to a class of chemical compounds consisting of a hydroxyl group ( — OH) bonded directly to an aromatic hydrocarbon group. The phenol group includes phenol, catechol, m+P cresols, and o-cresol.

For the purposes of the invention, the term "paper material" generally denotes a web of cellulosic fibres in sheet form. As used herein with reference to the invention, the term “sheet” is used to describe a laminar element having a width and a length substantially greater than a thickness thereof. The sheet may have a thickness ranging from 0.1 to 2 millimetres and a basis weight of from 50 grams per square metre to 300 grams per square metre.

To form the web, an aqueous slurry of pulp fibres is drained through a sieve-like screen, so that a mat of randomly interwoven fibres is laid down. Water is further removed from this mat by pressing, optionally assisted by suction or vacuum, or by heating, or both. Once the drying process is complete, a generally flat and uniform sheet of paper material is obtained.

Advantageously, using a paper material, which comprises randomly oriented cellulose fibres, facilitates degradation of the plug element. This is because the randomly oriented fibres can more easily disperse after the plug element has been discarded, particularly when compared with the substantially continuous filaments of traditional cellulose acetate tow filters. Increased dispersion of the fibres increases the exposure of the individual fibres to the environment, thus increasing the rate at which the plug element degrades.

The term “pulp” is used to denote a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops, waste paper, or rags.

The term “cellulose” denotes an organic compound with the formula (CeHwOs A polysaccharide consisting of a linear chain of several hundreds to many thousands of D- glucose units joined by a glycosidic-bond, cellulose is a structural component of the primary cell wall of green plants and many algae.

The term “hemicellulose” identifies a groups of polysaccharides typically present with cellulose in almost all terrestrial plant cell walls. The hemicellulose polysaccharides are shorter than cellulose and typically branched. From a chemical viewpoint, while cellulose is derived exclusively from glucose, hemicellulose polysaccharides include both five-carbon sugars (xylose and arabinose) and six-carbon sugars (mannose and galactose on top of glucose). Additionally, acidified forms of sugars - such as glucuronic acid and galacturonic acid - may be found in hemicellulose. As part of the papermaking process, fillers may be added to the pulp fibres prior to the formation of the web. Fillers used in the papermaking process are ordinarily inorganic, particulate substances, typically in the size range of 0.1 to 10 micrometres that may impart certain desirable properties to the paper material. For example, fillers may have an impact on the structure, appearance (for example, brightness and opacity), density, tensile strength and other measurable properties of the paper material. Examples of commonly used papermaking fillers include clay, limestone, chalk, talc, calcite, rutile (titanium dioxide), calcium sulphate, amorphous silica.

Preferably, the paper material does not include cellulose acetate fibres or any other fibres formed of non-biodegradable polymers.

The aerosol-generating article described herein may be received in a cavity of an aerosol-generating device. The aerosol-forming substrate of the aerosol-generating article may be heated in the cavity to create an inhalable aerosol.

The aerosol-generating device may comprise a mouth end through which in use an aerosol exits the aerosol-generating device and is delivered to a user. The mouth end may also be referred to as the proximal end. In use, a user draws on the proximal or mouth end of the aerosol-generating device in order to inhale an aerosol generated by the aerosolgenerating device. Alternatively, a user may directly draw on an aerosol-generating article inserted into an opening at the proximal end of the aerosol-generating device. The opening at the proximal end may be an opening of the cavity. The cavity may be configured to receive the aerosol-generating article. The aerosol-generating device comprises a distal end opposed to the proximal or mouth end. The proximal or mouth end of the aerosol-generating device may also be referred to as the downstream end and the distal end of the aerosol-generating device may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal, downstream or mouth end and the distal or upstream end of the aerosol-generating device.

As used herein, an ‘aerosol-generating device’ relates to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-forming substrate may be part of an aerosol-generating article, for example part of a smoking article. An aerosol-generating device may be a smoking device that interacts with an aerosol-forming substrate of an aerosolgenerating article to generate an aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. An aerosol-generating device may be a holder. The device may be an electrically heated smoking device. The aerosol-generating device may comprise a housing, electric circuitry, a power supply, a heating chamber and a heating element. As used herein with reference to the present invention, the term ‘smoking’ with reference to a device, article, system, substrate, or otherwise does not refer to conventional smoking in which an aerosol-forming substrate is fully or at least partially combusted. The aerosol-generating device of the present invention is arranged to heat the aerosol-forming substrate to a temperature below a combustion temperature of the aerosol-forming substrate, but at or above a temperature at which one or more volatile compounds of the aerosol-forming substrate are released to form an inhalable aerosol.

The aerosol-generating device may comprise electric circuitry. The electric circuitry may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of a controller. The electric circuitry may comprise further electronic components. The electric circuitry may be configured to regulate a supply of power to the heating element. Power may be supplied to the heating element continuously following activation of the aerosol-generating device or may be supplied intermittently, such as on a puff- by-puff basis. The power may be supplied to the heating element in the form of pulses of electrical current. The electric circuitry may be configured to monitor the electrical resistance of the heating element, and preferably to control the supply of power to the heating element dependent on the electrical resistance of the heating element.

The aerosol-generating device may comprise a power supply, typically a battery, within a main body of the aerosol-generating device. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, the power supply may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium- Iron-Phosphate, Lithium Titanate or a Lithium-Polymer battery. As an alternative, the power supply may be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that enables to store enough energy for one or more usage experiences; for example, the power supply may have sufficient capacity to continuously generate aerosol for a period of around six minutes or for a period of a multiple of six minutes. In another example, the power supply may have sufficient capacity to provide a predetermined number of puffs or discrete activations of the heating element.

The cavity of the aerosol-generating device may have an open end into which the aerosol-generating article is inserted. The open end may be a proximal end. The cavity may have a closed end opposite the open end. The closed end may be the base of the cavity. The closed end may be closed except for the provision of air apertures arranged in the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be arranged upstream of the cavity. The open end may be arranged downstream of the cavity. The cavity may have an elongate extension. The cavity may have a longitudinal central axis. A longitudinal direction may be the direction extending between the open and closed ends along the longitudinal central axis. The longitudinal central axis of the cavity may be parallel to the longitudinal axis of the aerosol-generating device.

The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received in the cavity. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular crosssection. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article.

An airflow channel may run through the cavity. Ambient air may be drawn into the aerosol-generating device, into the cavity and towards the user through the airflow channel. Downstream of the cavity, a mouthpiece may be arranged or a user may directly draw on the aerosol-generating article. The airflow channel may extend through the mouthpiece.

In any of the aspects of the disclosure, the heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required.

As described, in any of the aspects of the disclosure, the heating element may be part of an aerosol-generating device. The aerosol-generating device may comprise an internal heating element or an external heating element, or both internal and external heating elements, where "internal" and "external" refer to the aerosol-forming substrate. An internal heating element may take any suitable form. For example, an internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different electro-conductive portions, or an electrically resistive metallic tube. Alternatively, the internal heating element may be one or more heating needles or rods that run through the center of the aerosol-forming substrate. Other alternatives include a heating wire or filament, for example a Ni-Cr (Nickel-Chromium), platinum, tungsten or alloy wire or a heating plate. Optionally, the internal heating element may be deposited in or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as ceramic material, and then sandwiched in another insulating material, such as a glass. Heaters formed in this manner may be used to both heat and monitor the temperature of the heating elements during operation.

An external heating element may take any suitable form. For example, an external heating element may take the form of one or more flexible heating foils on a dielectric substrate, such as polyimide. The flexible heating foils can be shaped to conform to the perimeter of the substrate receiving cavity. Alternatively, an external heating element may take the form of a metallic grid or grids, a flexible printed circuit board, a molded interconnect device (MID), ceramic heater, flexible carbon fibre heater or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate. An external heating element may also be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating materials. An external heating element formed in this manner may be used to both heat and monitor the temperature of the external heating element during operation.

As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. In general, a susceptor is a material that is capable of generating heat, when penetrated by an alternating magnetic field. When located in an alternating magnetic field. If the susceptor is conductive, then typically eddy currents are induced by the alternating magnetic field. If the susceptor is magnetic, then typically another effect that contributes to the heating is commonly referred to hysteresis losses. Hysteresis losses occur mainly due to the movement of the magnetic domain blocks within the susceptor, because the magnetic orientation of these will align with the magnetic induction field, which alternates. Another effect contributing to the hysteresis loss is when the magnetic domains will grow or shrink within the susceptor. Commonly all these changes in the susceptor that happen on a nano-scale or below are referred to as “hysteresis losses”, because they produce heat in the susceptor. Hence, if the susceptor is both magnetic and electrically conductive, both hysteresis losses and the generation of eddy currents will contribute to the heating of the susceptor. If the susceptor is magnetic, but not conductive, then hysteresis losses will be the only means by which the susceptor will heat, when penetrated by an alternating magnetic field. According to the invention, the susceptor may be electrically conductive or magnetic or both electrically conductive and magnetic. An alternating magnetic field generated by one or several induction coils heat the susceptor, which then transfers the heat to the aerosol-forming substrate, such that an aerosol is formed. The heat transfer may be mainly by conduction of heat. Such a transfer of heat is best, if the susceptor is in close thermal contact with the aerosol-forming substrate.

As used herein, the term ‘aerosol-generating article’ refers to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. For example, an aerosol-generating article may be a smoking article that generates an aerosol that is directly inhalable into a user’s lungs through the user's mouth. An aerosolgenerating article may be disposable.

As used herein, the term ‘aerosol-forming substrate’ relates to a substrate capable of releasing one or more volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. An aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article.

The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosolforming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerine and propylene glycol.

The aerosol-generating substrate preferably comprises homogenised tobacco material, an aerosol-former and water. Providing homogenised tobacco material may improve aerosol generation, the nicotine content and the flavour profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenised tobacco involves grinding tobacco leaf, which more effectively enables the release of nicotine and flavours upon heating.

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 1. An aerosol-generating article comprising: a substrate portion comprising aerosol-forming substrate, a filter element, wherein the filter element comprises cellulosic filtration material, wherein the filter element comprises a filter wrapper wrapped around the cellulosic filtration material, wherein the filter wrapper has a grammage of 50 gsm to 120 gsm, and wherein the filter wrapper comprises a fluid impermeable coating.

Example 2. The aerosol-generating article according to example 1, wherein the cellulosic filtration material is free of cellulose acetate.

Example 3. The aerosol-generating article according to any of the preceding examples, wherein the cellulosic filtration material comprises a paper material, preferably wherein the cellulosic filtration material comprises a nonwoven paper material.

Example 4. The aerosol-generating article according to any of the preceding examples, wherein the cellulosic filtration material comprises a fibrous material comprising a plurality of regenerated cellulose fibres, wherein the regenerated cellulose fibres are one or more of viscose fibres, modal fibres, Lyocell fibres and viscose rayon fibres.

Example 5. The aerosol-generating article according to any of the preceding examples, wherein the cellulosic filtration material comprises a fibrous material comprising a plurality of natural fibres, wherein the natural fibres are one or more of are one or more of flax fibres, hemp fibres, jute fibres, kenaf fibres, ramie fibres, abaca fibres, phormium fibres, sisal fibres, coir fibres, cotton fibres, and kapok fibres.

Example 6. The aerosol-generating article according to any of the preceding examples, wherein the filter wrapper has a grammage of 60 gsm to 110 gsm, preferably wherein the filter wrapper has a grammage of 70 gsm to 100 gsm.

Example 7. The aerosol-generating article according to any of the preceding examples, wherein the cellulosic filtration material comprises an additive.

Example 8. The aerosol-generating article according to example 7, wherein the additive is a phenol scavenger.

Example 9. The aerosol-generating article according to example 7 or 8, wherein the additive comprises triethyl citrate, preferably liquid triethyl citrate.

Example 10. The aerosol-generating article according to any of examples 7 to 9, wherein the cellulosic filtration material comprises, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% triethyl citrate.

Example 11. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating is provided only on one side of the filter wrapper.

Example 12. The aerosol-generating article according to example 9, wherein the fluid impermeable coating is provided on the side of the filter wrapper facing the cellulosic filtration material.

Example 13. The aerosol-generating article according to any of examples 1 to 8, wherein the fluid impermeable coating is provided on both sides of the filter wrapper. Example 14. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating is coated onto the filter wrapper via rotogravure printing or flexo printing.

Example 15. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating comprises cellulose derivatives, preferably one or more of ethyl cellulose, microfibrillated cellulose and carboxymethyl cellulose.

Example 16. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating comprises fluorinated coatings.

Example 17. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating comprises one or more of: an acrylate, a styrene, a butadiene, a starch, a starch derivative, a cellulose derivative, an alginate, a polyvinyl alcohol, a polyvinyl acetate, polyfluoroalkyl, a gelatin, bio-wax and a gum.

Example 18. The aerosol-generating article according to any of the preceding examples, wherein the fluid impermeable coating is configured as a hardness-enhancing coating.

Example 19. A method for forming a filter element of the aerosol-generating article, comprising: providing cellulosic filtration material, providing a filter wrapper, wherein the filter wrapper has a grammage of 50 gsm to 120 gsm, coating the filter wrapper with a fluid impermeable coating, and

- wrapping the filter wrapper around the cellulosic filtration material.

Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 shows an illustrative side view of an aerosol-generating article.

Figure 1 shows an aerosol-generating article 10. The aerosol-generating article 10 is elongate and rod shaped.

The aerosol-generating article 10 comprises a substrate portion 12. Aerosol-forming substrate is arranged in the substrate portion 12. The substrate portion 12 may be surrounded by a substrate wrapper. Figure 1 further shows a cooling portion 14 of the aerosol-generating article 10. The cooling portion 14 is arranged downstream of the substrate portion 12. The cooling portion 14 is tubular and hollow. The cooling portion 14 may comprise perforations (not shown) to allow ambient air to be drawn into the cooling portion 14.

Figure 1 further shows a filter element 16. The filter element 16 is arranged downstream of the cooling portion 14. In other words, the cooling portion 14 is arranged between the substrate portion 12 and the filter element 16. The filter element 16 comprises cellulosic filtration material. The cellulosic filtration material is arranged inside of the filter element 16. The cellulosic filtration material is provided as a bulk material. The cellulosic filtration material filters the air flowing through the filter element 16.

A filter wrapper 18 is arranged wrapped around the cellulosic filtration material. Hence, the filter element 16 is formed by the cellulosic filtration material and the filter wrapper 18. Optionally (not shown) a tipping paper may be arranged connecting the filter element 16, the cooling portion 14 and the substrate portion 12.

The filter wrapper 18 is provided with a fluid impermeable coating. Preferably, the fluid impermeable coating is provided only on one side of the filter wrapper 18. Particularly preferred, the fluid impermeable coating is provided on the inner side of the filter wrapper 18. In other words, the fluid impermeable coating is particularly preferably arranged on the side of the filter wrapper 18 facing the cellulosic filtration material. Alternatively, the fluid impermeable coating is provided on both sides of the filter wrapper 18 or only on the outer side of the filter wrapper 18.

An additive (not shown) may be provided in the cellulosic filtration material. The additive is preferably a fluid phenol scavenger. Particularly preferably, around 3 wt% of triethyl citrate is provided as a phenol scavenger in the cellulosic filtration material. The fluid impermeable coating prevents the fluid additive to contact the filter wrapper 18 thereby preventing staining of the filter wrapper 18 and preventing the filter wrapper 18 from becoming soggy.

Claims

1. An aerosol-generating article comprising: a substrate portion comprising aerosol-forming substrate, a filter element, wherein the filter element comprises cellulosic filtration material, wherein the filter element comprises a filter wrapper wrapped around the cellulosic filtration material, wherein the filter wrapper has a grammage of 50 gsm to 120 gsm, and wherein the filter wrapper comprises a fluid impermeable coating, wherein the fluid impermeable coating comprises fluorinated coatings.

2. The aerosol-generating article according to claim 1 , wherein the cellulosic filtration material is free of cellulose acetate.

3. The aerosol-generating article according to any of the preceding claims, wherein the cellulosic filtration material comprises a paper material, preferably wherein the cellulosic filtration material comprises a nonwoven paper material.

4. The aerosol-generating article according to any of the preceding claims, wherein the filter wrapper has a grammage of 60 gsm to 110 gsm, preferably wherein the filter wrapper has a grammage of 70 gsm to 100 gsm.

5. The aerosol-generating article according to any of the preceding claims, wherein the cellulosic filtration material comprises an additive.

6. The aerosol-generating article according to claim 5, wherein the additive is a phenol scavenger.

7. The aerosol-generating article according to claim 5 or 6, wherein the additive comprises polyethylene glycol, preferably 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% polyethylene glycol.

8. The aerosol-generating article according to any of claims 5 to 7, wherein the cellulosic filtration material comprises, as additive, 1 wt% to 5 wt%, preferably 2 wt% to 4 wt%, more preferably 3 wt% low molecular weight polyethylene glycol, preferably having a weight average molecular weight M_w of between 300 and 500, more preferably of between 350 and 450, most preferably of 400.

9. The aerosol-generating article according to any of the preceding claims, wherein the fluid impermeable coating is provided only on one side of the filter wrapper.

10. The aerosol-generating article according to claim 9, wherein the fluid impermeable coating is provided on the side of the filter wrapper facing the cellulosic filtration material.

11. The aerosol-generating article according to any of the preceding claims, wherein the fluid impermeable coating comprises cellulose derivatives, preferably one or more of ethyl cellulose, microfibrillated cellulose and carboxymethyl cellulose.

12. The aerosol-generating article according to any of the preceding claims, wherein the fluid impermeable coating comprises one or more of: an acrylate, a styrene, a butadiene, a starch, a starch derivative, a cellulose derivative, an alginate, a polyvinyl alcohol, a polyvinyl acetate, polyfluoroalkyl, a gelatin, bio-wax and a gum.

13. The aerosol-generating article according to any of the preceding claims, wherein the fluid impermeable coating is configured as a hardness-enhancing coating.

14. A method for forming a filter element of an aerosol-generating article, comprising: providing cellulosic filtration material, providing a filter wrapper, wherein the filter wrapper has a grammage of 50 gsm to 120 gsm, coating the filter wrapper with a fluid impermeable coating, wherein the fluid impermeable coating comprises fluorinated coatings, and

- wrapping the filter wrapper around the cellulosic filtration material.