WO2024115568A1

WO2024115568A1 - Filter for an aerosol generating article

Info

Publication number: WO2024115568A1
Application number: PCT/EP2023/083544
Authority: WO
Inventors: Kenichi ITABASHI; Ahmad LISAN; Damir KUCHKAROV
Original assignee: Jt International Sa
Priority date: 2022-11-29
Filing date: 2023-11-29
Publication date: 2024-06-06

Abstract

The invention relates to a filter for use in a smoking or aerosol generating article and an aerosol generating article comprising the filter. The filter comprising a nonwoven substrate comprising natural fibers and a binder, wherein the natural fibers represent 85% to 95%, preferably 86.9 to 95% by weight of the nonwoven substrate, and the binder represents 5 to 15%, preferably 5 to 13.1% by weight of the nonwoven substrate, wherein the nonwoven substrate has a dry tensile strength of at least 10 N/5cm, preferably at least 12 N/5cm and most preferably at least 14 N/5cm, and the nonwoven substrate has a thickness from 0.4 to 1.0 mm, preferably from 0.5 to 0.9mm, and most preferably from 0.5 to 0.7 mm.

Description

FILTER FOR AN AEROSOL GENERATING ARTICLE

TECHNICAL FIELD

The present invention relates to a filter, and an aerosol generating article comprising the filter, for use in a smoking or aerosol generating article comprising a nonwoven substrate comprising natural fibers and a binder.

BACKGROUND

In the past years smoking articles, such as cigarettes have been equipped with acetate filters to filter unhealthy components from the aerosols inhaled by a user. However, when thrown away, the used cigarettes, and the filters in particular, often end up in the environment, which may cause harm to the environment. Due to the increase in environmental awareness of consumers, replacing the commonly used non- biodegradable filters with biodegradable filters comprising natural materials is becoming a more and more sought-after aim for manufacturers.

For example, in GB 2525363 A, a biodegradable cigarette filter tow is disclosed that includes a mixture of at least two or more natural materials selected from the group consisting of hemp fibre, flax fibre, abaca fibre or pulp, sisal fiber or pulp, wood pulp or cotton fibre or cotton flock, and a natural binder.

WO 2022/053621 relates to a filter comprising a nonwoven substrate having a low density and comprising natural fibers and a binder, wherein the filter can be used as a filter for a smoking or vaping article.

While the prior art discloses filters comprising natural nonwoven material, due to the low density of the filter, the nonwoven substrate may break during filter manufacturing, especially in/after crimping process which is normally used for filter production for sheet substrate and the filter has a risk of falling apart, which can cause an unpleasant smoking experience for a user. Moreover, during production of nonwoven substrates, the binder tends to leak out of the nonwoven substrate, contaminating the manufacturing machines, which reduces the yield of the filter production.

It is thus desired to provide a filter which can be manufactured with reduced risk of breaking during production and with a reduced risk of falling apart during use and a reduced risk of binder leakage during production of the non-woven substrate. It is desired to provide a method for manufacturing the filter.

SUMMARY OF THE INVENTION

The present invention provides a filter with a nonwoven substrate comprising natural fibers and a binder that solves some or all of the above problems.

A 1st embodiment of the invention is directed to a filter for use in a smoking or aerosol generating article, the filter comprising a nonwoven substrate comprising natural fibers and a binder, wherein the natural fibers represent from 85 to 95%, preferably 86.9 to 95% by weight of the nonwoven substrate, and the binder represents from 5 to 15% , preferably 5 to 13.1% by weight of the nonwoven substrate, wherein the nonwoven substrate has a dry tensile strength of at least 10 N/5 cm, preferably at least 12 N/5 cm and most preferably at least 14 N/5 cm, and the nonwoven substrate has a thickness of from 0.4 to 1.0 mm, preferably 0.5 to 0.9 mm, and most preferably from 0.5 to 0.7 mm. Preferably, the natural fiber represents more than 85 to 90% by weight of the nonwoven substrate and the binder represents from 5 to less than 15 % by weight of the nonwoven substrate.

Filters manufactured from nonwoven substrates with a tensile strength below 10 N/5 cm have an increased risk of breaking of the substrate during manufacturing or in falling apart due to the low tensile strength. The above composition results in a filter made of natural material that is durable and has inhaling and nicotine retention properties similar to what consumers are used to from filters known in the art. Moreover, the leaking of the binder from the nonwoven substrate during manufacturing is reduced.

According to a 2nd embodiment, in the preceding embodiment, the natural fibers represent from 90 to 93% by weight of the nonwoven substrate, and/or the binder represents 7 to 10% by weight of the nonwoven substrate.

Preferably, the natural fibers represent from 91 to 95% by weight of the nonwoven substrate, and/or the binder represents 5 to 9% by weight. More preferably, the natural fibers represent from 93 to 95% by weight of the nonwoven substrate, and/ or the binder represents from 5 to 7% by weight. The reduced amount of binder provides an improved biodegradability.

Furthermore, in any of the preceding embodiments, the natural fibers represent at least 86% by weight of the nonwoven substrate, preferably at least 87% by weight of the nonwoven substrate, more preferably at least 88% by weight of the nonwoven substrate, and most preferably at least 89% by weight of the nonwoven substrate, and/or at most 95% by weight of the nonwoven substrate, preferably at most 94% by weight of the nonwoven substrate, and most preferably at most 93% by weight of the nonwoven substrate, and/or the binder represents at most 14% by weight of the nonwoven substrate, preferably at most 13% by weight of the nonwoven substrate, more preferably at most 12% by weight of the nonwoven substrate, and most preferably at most 11% by weight of the nonwoven substrate, and/ or at least 5% by weight of the nonwoven substrate, preferably at least 6% by weight of the nonwoven substrate, and most preferably at least 7% by weight of the nonwoven substrate.

According to a 3rd embodiment, in any one of the preceding embodiments, the nonwoven substrate has a volume density of at least 50 mg/cm³, preferably of at least 55 mg/cm³ and most preferably of at least 60 mg/cm ³, and/or a volume density of at most 140 mg/cm3, preferably at most 130 mg/cm3, even preferably at most 120 mg/cm3, of at most preferably 110 mg/cm³, or at most too mg/cm³ or at most 90 mg/cm³.

According to a 4th embodiment, in any one of the preceding embodiments, the nonwoven substrate has an areal density of from 40 to 65 g/m², preferably 45 to 60 g/m² and most preferably from 46 to 58 g/m².

With the above embodiments, the risk of leakage from the binder can be further reduced.

According to a 5th embodiment, in any one of the preceding embodiments, the average length of the natural fibers is at most 3.5 mm, preferably at most 3.0 mm and most preferably at most 2.8 mm, and/or the average length of the natural fibers is at least 2.0 mm, preferably at least 2.3 mm and most preferably at least 2.5 mm. According to a 6th embodiment, in any one of the preceding embodiments, the natural fibers comprise or preferably consist of wood pulp, the wood pulp preferably being obtained by a kraft process.

According to a 7th embodiment, in the preceding embodiment, the wood pulp comprises a soft wood pulp and/or a hard wood pulp, preferably a Southern bleached softwood kraft, SBSK, and/or a Northern bleached softwood kraft, NBSK, wherein preferably the wood pulp comprises at least 75% SBSK, preferably at least 85% SBSK, more preferably at least 95% SBSK and most preferably 100% SBSK and/or preferably 25% NBSK or less, more preferably 5% NBSK or less.

Using natural fibers reduces the negative environmental impact of the filters. Moreover, nonwoven substrates made from wood pulp provide filter capabilities (pressure drop and nicotine retention properties) similar to filters known in the art. Consequently, the negative environmental impact of the filters can be reduced while similar filter capabilities are maintained. Moreover, the higher percentage of SBSK tends to reduce the pressure drop of the filter compared to higher percentage of NBSK. So, the ratio of SBSK to NBSK may be used to adjust the pressure drop of the filter.

According to an 8th embodiment, in any one of the preceding embodiments, the binder comprises at least one binding agent being a water-based polymer emulsion, preferably solvable in water.

According to a 9th embodiment, in any one of the preceding embodiments, the binder comprises one or more of an aqueous copolymer dispersion of Ethylene Vinyl Acetate, EVA, and a Polyvinyl Acetate, PVAc, adhesive.

According to a 10th embodiment, in the preceding embodiment, the binder comprises a combination of EVA and PVAc adhesive, wherein the ratio of EVA to PVAc adhesive is preferably between 70:30 and 30:70, more preferably between 60:40 and 40:60, even more preferably between 55:45 and 45:55 and most preferably 50:50.

According to an 11th embodiment, in the 9th or 10th embodiment, the PVAc adhesive is a Polyvinyl alcohol stabilized polyvinyl acetate, preferably stabilized by a vinyl alcohol polymer, PVOH, a dextrin, or combinations thereof, wherein the EVA is stabilized with one or more of a surfactant, an emulsifier, a cellulose derivate, PVOH, a colloid, and combinations thereof. The above binders, and water-soluble binders in general increase the degradation speed of the filters in the environment. That is, if subjected to rain or the soil, the water- soluble binder dissolves and the filter falls apart more easily, which in turn speeds up the natural degradation of the filter.

According to a 12th embodiment, in any one of the preceding embodiments, the nonwoven substrate comprises flavor additives.

Adding flavor additives to the filter improves the consumer experience. In particular, the flavor additives can mask the taste of the natural fiber material comprised in the filter.

According to a 13th embodiment, in any one of the preceding embodiments, a reel width of the non-woven substrate is between 50 and 240 mm, preferably 100 and 220 mm, for example between 120 and 180 mm.

The reel width may depend on the circumference of the filter. The smaller the circumference, the narrower the width is. More particularly, when the circumference of the filter is about 16.8 mm (“super slim” format), the reel width is preferably between 50 and too mm. When the circumference of the filter is about 21.5 mm (“Slim format”), the reel width is preferably between too and 160mm. When the circumference of the filter is about 24.2 mm (“King size format”), the reel width is preferably between 120 and 180 mm.

According to a 14th embodiment, in any one of the preceding embodiments, the nonwoven substrate is crimped in the machine direction with a crimping depth of 0.2 to 1.2 mm, preferably 0.2 to 1.0 mm, more preferably of 0.5 to 1.0 or 0.5 to 0.9 mm.

A crimping depth in the above range reduces the risk of unwanted cracks in the nonwoven substrate, while the desired crimping effect is obtained.

According to a 15th embodiment, in any one of the preceding embodiments, the filter has a density between 100 and 220 mg/cm³ or between 100 and 200 mg/cm³, for example of 140 mg/cm³, and/or the pressure drop at the filter is between 1.3 and 5.0 mmWC/mm or between 1.3 and 4.5 mmWC/mm, preferably between 1.8 and 3 mmWC/ mm, preferably determined according to the conditions described in ISO 6565:2015. According to a 16th embodiment, in any one of the preceding embodiments, the hardness of the filter corresponds to a decrease in the diameter of the filter in the range of 2.5 mm to 1.3 mm, more preferably in the range of 2.3 mm to 1.5 mm, preferably when being subjected to a pressure of 350g for 5s in a SODIM-H hardness measurement module.

A pressure drop in the above range is similar to the pressure drop of conventional cellulose acetate filters. Accordingly, a user consuming a smoking article/aerosol generating device with the described filter has the desired consuming experience.

According to a 17th embodiment, in any one of the preceding embodiments, the nonwoven substrate is brought in a rod-shaped form and is wrapped by a wrapping paper having a basis weight of from 24 to 120 gsm, or 25 to 50 gsm, preferably from 27 to 45 gsm and/or a thickness of from 0.03 to 0,13 mm or from 0.03 to 0.06 mm, preferably from 0.043 to 0.125 mm.

For example, the circumference may be between 16 to 28 mm, for example 16.8 mm, or about 16 to 26 mm, for example 21.5 mm, or about 16.8 to 24.20 mm.

According to an 18th embodiment, in the preceding embodiment, a circumference of the filter is between 16 to 28 or 20 and 28 mm, preferably between 22 and 26 mm, even more preferably between 24 and 25 mm, and most preferably 24.2 mm.

The above ranges are commonly used in state-of-the-art smoking articles/aerosol generating devices. Accordingly, a filter in the above range can be used in a variety of applications.

A 19th embodiment is directed to an aerosol generating article, preferably a cigarette or heat-not-burn aerosol generating article, comprising a filter according to any one of the preceding embodiments.

A 20th embodiment is directed to a method for manufacturing of a filter comprising a nonwoven substrate, preferably a filter according to any one of the first to 18^th embodiment, for use in a smoking or aerosol generating article, the method comprising the steps of providing a nonwoven substrate arranged as a continuous sheet (also referred to herein as “festoon”) on a bale or pallet, inserting the nonwoven substrate into a production facility for production of the filter, and crimping the nonwoven substrate into the filter. Preferred embodiments are now described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1: is a plot showing the tensile strength measurements results of exemplary nonwoven substrates at various thicknesses and binder contents;

Figure 2: is another plot showing the tensile strength measurements results of exemplary nonwoven substrates at various thicknesses and binder contents;

Figure 3: is a plot of the firmness against the pressure drop of exemplary filters comprising nonwoven substates;

Figure 4a: shows an arrangement of nonwoven material according to a first embodiment;

Figure 4b: shows an arrangement of nonwoven material according to a second embodiment;

Figure 5: shows the space requirement of a nonwoven substrate stored on a bale/pallet by means of festooning process with the space requirement of a nonwoven substrate supplied by bobbins, i.e. by a known rolling process.

DETAILED DSCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described hereinafter with reference to the drawing.

In the following, a filter comprising a nonwoven substrate for use in a smoking or aerosol generating article is described in more detail.

Nonwoven substrates relate to substrates made from fiber material where the fibers are bonded together mechanically, chemically or by means of a binder, and are well known in the art.

A filter according to an embodiment comprises a nonwoven substrate comprising natural fibers and a binder. Preferably, the nonwoven substrate is provided as a sheet. In the nonwoven substrate, the natural fibers represent 85% to 95% by weight of the nonwoven substrate and the binder represents 5 to 15% by weight of the nonwoven substrate. Preferably, the natural fiber represents more than 85% to 90% by weight of the nonwoven substrate and the binder represents from 5 to less than 15 % by weight of the nonwoven substrate.

To avoid that the nonwoven substrate breaks during filter production and/or the filter comprising the nonwoven substrate falls apart, a nonwoven substrate is used with a diy tensile strength of at least 10 N/5 cm, preferably at least 12 N/5 cm and most preferably at least 14 N/5 cm, and/or a thickness of 0.4 to 1.0 mm, preferably 0.5 to 0.9 mm, and most preferably 0.5 to 0.7 mm. Filters comprising such a nonwoven substrate have proven to be particularly resistant against falling apart and were produced with a high yield. The thickness of the nonwoven substrate is measured by using a thickness gauge apparatus applying a pressure of 0.5 kPa on the specimen with a pressing surface area of 25 cm² according to EN ISO 9073-2:1996 “Test methods for nonwovens”.

In some embodiments, the natural fibers represent 90 to 93% by weight of the nonwoven substrate, and/or the binder represents 7 to 10% by weight of the nonwoven substrate. More preferably, natural fibers represent between more than 90 % and 93% by weight of the nonwoven substrate, the binder represents between 7 and less than 10% by weight of the nonwoven substrate.

In some embodiments, the nonwoven substrate has a volume density, also referred to as sheet density, of at least 50 mg/cm³, preferably of at least 55 mg/cm³ and most preferably of at least 60 mg/cm³, and/or a volume density of at most 140 mg/cm³, preferably at most 130 mg/cm³, even preferably at most 120 mg/cm³, most preferably at most 110 mg/cm³, preferably of at most 100 mg/cm³ and most preferably of at most 90 mg/cm³.

The volume density of the nonwoven substrate can be obtained by dividing the areal density or grammage of the substrate by its thickness.

In some embodiments, the nonwoven material has an areal density, also referred to as grammage, of 40 to 65 g/m², preferably of 45 to 60 g/m² and most preferably of 46 to 58 g/m².

The areal density of a sheet of nonwoven substrate is determined by placing the sheet on a balance and measuring the weight. Afterwards the weight is divided by the area of the sample and the areal density/grammage is obtained. For example, the standard ISO 536:2019 can be used to determine the areal density of the nonwoven substrate.

The higher the areal/ volume density of the nonwoven material for a given length, the higher the pressure drop of a filter that is manufactured using the nonwoven material.

The natural fiber material for the nonwoven substrate may be selected from one or more of wood fibers, cotton fibers, leaf fibers, such as abaca or sisal fibers, bast fibers, such as jute, hemp, flax or kenaf fibers, and/or semi natural fibers such as viscose and/or lyocell fibers. While the natural fibers maybe selected from any of the above, in some embodiments it is desired to select a natural fiber with a particularly good biodegradability, such that the environmental friendliness can be improved.

For example, the natural fibers may comprise or preferably consist of wood fibers selected from soft wood pulp or hardwood pulp, or a combination thereof. Preferably, the natural fibers comprise at least 50%, more preferably at least 70%, even more preferably at least 90%, even more preferably at least 95%, and most preferably 100% wood fibers. Preferably, the pulping process is a kraft pulping process, and the natural fibers are Southern bleached softwood kraft (SBSK) and/or Northern bleached softwood kraft (NBSK), wherein the wood pulp comprises at least 75% SBSK, preferably at least 85% SBSK, more preferably at least 95% SBSK and most preferably 100% SBSK (percentage in weight).

The average length of the natural fibers, according to some embodiments, is at most 3.5 mm, preferably at most 3.0 mm and most preferably at most 2.8 mm, and/or the average length of the natural fibers is at least 2.0 mm, preferably at least 2.3 mm and most preferably at least 2.5 mm.

An exemplary SBSK material suited for the filter is Golden Isles Treated fluff, grade 4623. This material has a fiber length of 2.68 mm and a basis weight of 765 g/m².

The binder added to the natural fibers to form the nonwoven substrate may comprise at least one binding agent being a water-based polymer emulsion, preferably water soluble. The binder may be selected from one or more of an aqueous copolymer dispersion of Ethylene Vinyl Acetate, EVA, and a Polyvinyl Acetate, PVAc, adhesive, a cellulose derivative, such as ethyl/methyl cellulose, hydroxyethyl/ -methyl cellulose IO and/or carboxymethyl cellulose and/or a polysaccharide (or a derivative of a polysaccharide) such as dextrin or starch.

In some embodiments, the binder is selected from one or more of an aqueous copolymer dispersion of Ethylene Vinyl Acetate, EVA, and a Polyvinyl Acetate, PVAc, adhesive. Preferably, the ratio of EVA to PVAc adhesive is between 70:30 and 30:70, more preferably between 60:40 and 40:60 and most preferably between 55:45 and 45:55- In some embodiments the ratio of EVA to PVAc adhesive is 50:50. One benefit of these binders is that they do not have any negative impact on the phenol delivery.

The PVAc adhesive may be a PVAc stabilized by PVOH (vinyl alcohol polymer), dextrin and combinations thereof, more preferred a PVAc adhesive stabilized with PVOH. The advantages of the PVAc adhesive are high bonding properties with the natural fibers, fast setting of the binder and its compatibility with the EVA dispersion. An exemplary polyvinyl alcohol stabilized polyvinyl acetate (PVAc) adhesive is Vinamul 8482, commercialized by Celanese.

An exemplary copolymer of the EVA is a copolymer of EVA stabilized with surfactant, emulsifier, cellulose derivative, PVOH, colloid and combinations thereof. The copolymer is hydrophilic so that it can easily wet the fiber material and has good adhesion properties. Preferred is a copolymer of EVA in an aqueous copolymer dispersion with self-crossing properties based in vinyl acetate and ethylene stabilized with surfactants. This copolymer provides a particularly neutral taste and has a low volatile organic compound (VOC) content.

To produce filters from the nonwoven sheet, the nonwoven sheet preferably has a reel width of 50 to 240 mm or too to 220 mm, preferably 70 to 170 or 120 to 180 mm.

Preferably, the nonwoven substrate is stored on one or more bales/pallets, preferably by a festooning process. In other words, the nonwoven material can be stored arranged as a continuous sheet, also indicated herein with the term “festoon”, preferably to form a bale. The continuous sheet of nonwoven material, or the bale formed by the continuous nonwoven material, can be arranged on a pallet or similar supports. It has to be noted that the term “continuous sheet” is herein used to indicate a single continuous sheet made as a one piece, as well as to indicate a sheet made up of spliced portions of nonwoven sheets. In other words two or more portions of nonwoven material can be joined together to form a continuous sheet. For example, bobbins currently used in art can be spliced together to form a continuous sheet on nonwoven material. For example, the material of two or more bobbins, such as of io bobbins, can be “converted”, i.e. arranged, in a continuous sheet stored on a bale/pallet.

In the following, the festooning process for storing the nonwoven substrate, i.e. for storing the nonwoven substrate on a bale and/or a pallet, as well as the process for supplying the nonwoven substrate from the bale/pallet to the filter making apparatus for producing the filter, are described in more detail.

According to a first embodiment, a plurality of individual layers of a continuous sheet of nonwoven substrate are arranged on a pallet and/ or bale. As mentioned above, the continuous sheet of nonwoven material, or the bale formed by the continuous nonwoven material, can be arranged on a pallet or similar supports.

One such example is shown in Fig. 4a. Adjacent portions (401a, 401b, 401c) of the continuous nonwoven sheet are arranged adjacent to each other in in a substantially horizontal direction H, wherein the adjacent portions (401a, 401b, 401c) may overlap partially. The nonwoven substrate is arranged on the pallet or bale such that during removal of the nonwoven substrate from the pallet or bale, an individual first layer of the nonwoven substrate is removed before an individual second layer below the individual first layer of the nonwoven substrate is removed from the pallet or bale. Moreover, the nonwoven substrate is arranged on the pallet or bale such that portions (401a, 401b, 401c) of the nonwoven substrate that form the individual layer are removed from the pallet or bale in the substantially horizontal direction H. Moreover, each of the individual layers of nonwoven material may extend over the total area of the pallet or bale. The nonwoven substrate arranged as described above, preferably by means of a festooning process (that can be carried out at the same plant where the filter is produced, or that can be carried out previously at a different plant where the filter is produced), is provided for production of the filter in direction P. It has to be noted that the festooning process to create the bale is preferably carried out in a non-woven process plant, e.g. of a non-woven supplier, but it is not excluded that the festooning process to create the bale can be carried out at the same plant where the filter is produced.

In a second embodiment, the nonwoven substrate is provided on the pallet and/or bale, wherein individual (420a, 420b) stacks of nonwoven material are arranged next to each other. As mentioned above, the continuous sheet of nonwoven material, or the bale formed by the continuous nonwoven material, can be arranged on a pallet or similar supports. One such example is shown in Fig. 4b. In this example, adjacent portions (402a, 402b) of the continuous nonwoven sheet are arranged above/below each other in a substantially vertical direction V, wherein the adjacent portions may overlap substantially completely. While in the previous example adjacent portions (402a, 402b) of the continuous nonwoven sheet are arranged adjacent to each other forming individual layers, in this example, adjacent portions (402a, 402b) of the continuous nonwoven sheet are arranged above/below each other, forming the individual stacks (420a, 420b) of the nonwoven substrate. The nonwoven substrate is arranged on the pallet or bale such that during removal of the nonwoven substrate from the pallet or bale, an individual first stack (420a) of the nonwoven substrate is removed before an individual second stack (420b) adjacent to the individual first stack (420a) of the nonwoven substrate is removed from the pallet or bale. Moreover, the nonwoven substrate is arranged on the pallet or bale such that portions (402a, 402b) of the nonwoven substrate that form the individual stacks (420a, 420b) are removed from the pallet or bale in the substantially vertical direction V. Moreover, each of the individual stacks (420a, 420b) of nonwoven material may extend over the total height of the nonwoven substrate arranged on the pallet or bale. The nonwoven substrate arranged as described above, preferably by means of a festooning process, is provided for production of the filter in direction P. It has to be noted that the festooning process to create the bale is preferably carried out in a non-woven process plant, e.g. of a nonwoven supplier, but it is not excluded that the festooning process to create the bale can be carried out at the same plant where the filter is produced.

Providing the nonwoven substrates, stored in the form of a bale and/or on pallet using festooning process, has the advantage of reduced area requirement in a production facility compared to other widely used arrangements, such as a rolling process, where the nonwoven sheet is arranged on one or more bobbins.

In Figure 5 the difference in space requirement between a rolling process [a] and the feeding of the nonwoven substrate stored on a bale/pallet by a festooning process [b] for manufacturing the filter is illustrated. Typically, in the rolling process [a], at least two large bobbins (501) are provided for providing the nonwoven substrate to the production facility. Typically, the nonwoven substrate is fed from the bobbins (501) into a buffer (502) before it is transferred into the crimping unit (510). When there is the need to change the bobbin it is necessary to stop its rotation movement, the buffers allows the splicing of the nonwoven substrate from the bobbin currently in use to the subsequent bobbin, while allowing the manufacturing process of the filter to continue without interruption. Contrary to this, when the nonwoven substrate has been stored in a bale/pallet by aa festooning process [b], the nonwoven substrate provided on bales or pallets (503) can be fed (pulled from the bale/pallet) directly into the filter manufacturing process, e.g in a crimping unit (510) thereof, for production of the filter. Due to the nonwoven substrate being provided on a bale or pallet, the buffer for splicing the substrate is at least reduced, or in some embodiments it is not necessary, in the festooning process. In fact, it is possible to connect the nonwoven substrate from the bale /pallet currently in use to the leading end of the nonwoven substrate of the subsequent bale/pallet to be used, well before the trailing end of the nonwoven substrate of the bale/pallet currently in use is fed to the crimping unit. In other words, the splicing of the nonwoven substrate of two bales/pallets can be easily carried out since the trailing end of the nonwoven substrate is always available, contrary to the bobbins arrangement wherein the nonwoven substrate is rotating thus to operate on the nonwoven substrate or on the bobbin it is necessary to stop its rotation movement.

This also leads to significantly less space requirement in the production facility, when compared to the space required for the rolling process. To this regard it has to be noted that festooning process allows to store on a bale a nonwoven substrate having a length that is usually stored in about 10 bobbins of the known art.

Advantageously, the festooning process for storing the nonwoven substrate for example in the form of a bale, allows to provide biodegradable filters comprising nonwoven material with a similar layout in the production facility as for conventional filters, e.g. cellulose acetate filters, while providing less space requirements and a more efficient exchange of a subsequent feeding bale/pallet that does not require (or at least reduces) the buffer required in the know art to compensate for the bobbins rotation interruption.

To improve the quality of the filter obtained by the nonwoven substrate, in an exemplary embodiment, the nonwoven substrate is crimped before being formed into the filter. In this exemplary embodiment, the nonwoven substrate is crimped in the machine direction of a crimping machine with a crimping depth of 0.2 to 1.2 or 0.2 to 1.0 mm, preferably of 0.5 to 1.0 mm or 0.5 to 0.9 mm to obtain straight crimping grooves. The above ranges provided good filter properties without causing any breaks and cracks in the nonwoven substrate.

While the crimping process can increase the filter quality, for some embodiments this additional step can be removed from the manufacturing process, and the filter can be formed directly from the nonwoven substrate. The crimped nonwoven substrate may then be rolled from the sheet into the typical cylindrical filter shape/rod-shape by rolling the sheet about the longitudinal axis of the filter. In other embodiments, the crimped nonwoven substrate is pressed into the typical cylindrical filter shape/rod-shape. While cylindrical/rod shaped filters are most common in the art, the crimped nonwoven substrate may also have a rectangular shape, a conical shape, a spherically shape or any other shape that fits into the smoking article/aerosol generating device it is used for.

Additionally, flavoring agents may be added to the filter to provide a more pleasant smoking experience for the user.

To be compatible with commonly used smoking articles/aerosol generating devices, the circumference of the filter (including filter wrapper thickness) is preferably between 16 to 28 mm or 20 to 28 mm, more preferably between 22 to 26 mm, even more preferably 24 to 25 mm and most preferably of 24.2 mm. For example, the circumference may be between 16 to 28 mm, for example 16.8 mm, or about 16 to 26 mm, for example 21.5 mm, or about 16.8 to 24.20 mm.

To allow handling and contain the filtering substrate, the rolled nonwoven substrate may be wrapped by a wrapping paper with a basis weight of 24 to 120 gsm or 25 to 50 gsm, or 27 to toogsm and/or a thickness of 0.03 to 0.125 mm or 0.03 to 0.06 mm. For example, a plug wrap of 0.100 mm or 0.110 mm or 0.120 mm may advantageously provide an improved hardness of the filter.

Preferably a filter obtained with the above material has a density of 100 to 200 mg/cm³, preferably between 120 and 160 mg/cm³, for example 150 mg/cm³, wherein the pressure drop at the filter is between 1.3 and 4.5 mmWC/mm, preferably between 1.8 and 3 mmWC/mm, preferably determined according to the conditions described in ISO 6565:2015. The filter density may vaiy depending on the circumference of the filter. For example, when the filter circumference is about 16.8 mm, the filter density may be comprised between 106 and 211 mg/cm³, wherein the pressure drop is comprised between 2.78 and 4.44 mmWC/mm. When the filter is about 21.5 mm, the filter density may be comprised between 130 and 208 mg/cm³ wherein the pressure drop is comprised between 2.04 and 3.70 mmWC/mm. When the filter is about 24.2 mm, the filter density may be comprised between 123 and 184 mg/cm³ wherein the pressure drop is comprised between 1.67 and 4.44 mmWC/mm. EXEMPLARY NONWOVEN SUBSTRATES

In the following, worked examples of nonwoven substrate are discussed in detail. Table i shows four samples (lots 2, 4, 7 and 8) of nonwoven substrates that were manufactured considering the above-described properties.

5 Lots 2, 4, 7 and 8 were manufactured with a fiber content in the range of 86.9 to 91.8 %, and a corresponding binder content in the range of 8.2 to 13.1 %. From the four samples, lot 4 has the lowest binder content with 8.2%, followed by lot 7 with 8.5%, then followed by lot 2 with a binder content of 9.5% and lot 8 with the highest binder content of 13.1%.

10 For each of the samples, the areal density, the thickness, and the dry tensile strength were measured. To measure the tensile strength, a 5 cm strip of nonwoven substrate was cut off from the respective nonwoven substrate and clamped into a tensile strength measuring device. For example, a Zwick Roell tensile strength measurement device may be used, wherein the tensile strength is preferably measured under the testing

15 conditions defined in ISO 9073-3. However, other methods are also possible, such as the measurement method defined in ISO 9073-18:2007. In this particular example, the measurement method defined in ISO 9073-3 was conducted. The tensile strength measurement device applied a force to each end of the 5cm strip until the breaking point of the strip was reached and teared/broke. The required force and the elongation

20 of the strip were then measured.

Table 1 below shows the measurement results with regards to the densities, the thickness, and the tensile strength of the respective samples (lots 2, 4, 7 and 8). The sheet density was calculated by dividing the areal density by the thickness.

TABLE 1

As can be seen from table 1, the areal densities of the samples were within the range of 44.4 to 81.63 mg/cm³. The nonwoven substrate of lot 7 had the lowest areal density of 46.99 g/ m², followed by lot 4 with an areal density of 50.61, then by lot 8 with an areal density of 55.58 g/m² and lot 2 with the highest areal density of 55.58 g/m².

The respective thicknesses of the samples were within the range of 0.62 to 1.19 mm. From the four samples, lot 4 had the lowest thickness with a thickness of 0.62 mm, followed by lot 7 with a thickness of 0.78 mm, then by lot 2 with a thickness of 0.92 mm and lot 8 with a thickness of 1.19 mm.

The tensile strengths measured for the samples are within the range of 14.2 to 28.2. From the four samples, lot 7 has the lowest tensile strength with 14.2 N/5 cm, followed by lot 8 with a tensile strength of 14.7 N/ 5cm, then followed by lot 2 with a tensile strength of 18.0 N/5 cm and lot 4 with the highest tensile strength of 28.2 N/5 cm.

The above shows that generally, a high volume/sheet density of the nonwoven result in a high tensile strength of the material. However, the tensile strength of the filter depends also on the amount of binder and the thickness of the material. This can be seen in table 1, where lots 2 and 7 have similar volume densities but the tensile strengths vary significantly.

To show the effects of the particular parameters on the tensile strength, a second and a third batch of samples were prepared. In Figures 1 and 2, the tensile strength of the respective samples of the second and the third batch of nonwoven substrates are shown with respect to the respective thickness of the sample and the binder content. In Figure 1, the substrates in zones 1 and 4 showed tensile strengths that are sufficient for filter production, the substrates in zone 2 showed tensile strengths that are somewhat sufficient for filter production, and the substrates in zone 3 showed tensile strengths that are not sufficient for filter production, as they have an increased risk of tearing. Similarly, in Figure 2, zone 1 shows substrates with sufficient tensile strengths, zone 2 shows substrates with somewhat sufficient tensile strengths and zone 3 shows a substrate that does not have sufficient tensile strength for filter production.

As can be seen from Figure 1 in particular, if the areal density and the binder content are constant, the tensile strength decreases as the thickness decreases, which confirms the findings shown in table 1, where it was observed that as the volume density increases, the tensile strength increases. Furthermore, if the thickness, and thus the sheet/volume density is kept constant, the tensile strength increases with the binder content. Accordingly, the areal density, the thickness, and the binder content of the nonwoven all directly influence the resulting tensile strength.

Returning to the samples of table i, while each of the sheets of nonwoven substrate from each of lots 2, 4, 7 and 8 showed a sufficient tensile strength for producing filters, producing lots 7 and 8 was less productive compared to lots 2 and 4. This was because amounts of binder were leaking out of the substrates during production, which contaminated the machines used for producing the nonwoven sheet. This in turn led to the reduced productivity, as additional cleaning processes had to be added to the operation for producing lots 7 and 8.

The amount of binder leaking out of a nonwoven substrate depends also on the binder content, the thickness of the material, the areal density and thus also on the sheet/volume density. For example, a low volume density which can hardly prevent binder from escaping the nonwoven material increased the amount of binder leaking out of the device. Similarly, increasing the binder content while other parameters are constant also increases the amount of binder leaking out of the nonwoven substrate. Additionally, if the binder content and the volume density are constant, a lower thickness increases the effect of leakage, as less textile material is provided to prevent the binder from leaking.

Accordingly, while the parameters influencing the tensile strength suggest that a high binder content is desired, leaking also increases with a high binder content, which is to be prevented. Moreover, a too low thickness requires high pressure during production, which results in a non-uniform web of the nonwoven material. Accordingly, a nonwoven substrate with a relatively low thickness, such as in the range of 0.5 to 0.7 mm (high sheet/volume density) and/or with a relatively low binder content such as in the range of 10% -7% is most preferred.

FILTER PROPERTIES

From the nonwoven sample material, filters were formed by crimping the sheets of nonwoven material, rolling the crimped sheets into a rod-like shape, and wrapping the rod-like shaped nonwoven sheet with a wrapping paper, as described above.

The obtained filters were then subjected to pressure drop and firmness/hardness measurements to determine whether the filters, obtained according to the above describe method, show similar filtering properties as filters known in the art. The firmness/hardness and the pressure drop of the filters were measured using the hardness module (SODIM-H) and the pressure drop module (SODIM-PDVM) of the Sodiline measurement device. In the pressure drop module a critical flow orifice and a vacuum generator were provided in a laminar flow system. The vacuum generator was activated, and the pressure drop at the filter was measured (in mmWC). In the hardness module a mobile jaw applied pressure to the side of the filter (in axial direction of the cylinder-shaped filter) and the amount of compression was recorded (amount of deformation in tenth of mm).

Figure 3 shows the respective test results of a plurality of produced filters. The measured pressure drop of the filters is plotted against their respective measured hardness. In the measurement, a filter was subjected to the pressure of the 350g weights for 5s in SODIM-H. It can be seen that the pressure drop at the filter decreases as the filter’s firmness increases. Most preferred are pressure drops in the range of 1.3 to 5 mmWC/mm or 1.3 to 4.5 mmWC/mm, preferably between 1.8 mmWC/mm and 4.5 mmWC/mm or 1.8 and 3 mmWC/mm. Accordingly, the respective firmness of the filters are preferably in the range of 2.5 mm to 1.3 mm, more preferably in the range of 2.3 mm to 1.5 mm. These firmness ranges are achieved when filters are prepared as described above.

Thus, the filters obtained from the nonwoven material described above provide a pleasant inhaling experience for the user. Moreover, due to the high tensile strength of the material, the breaking of the nonwoven sheet is prevented. Moreover, the natural nonwoven fibers and the preferably water-soluble binder provide a more environmentfriendly filter.

FILTER DENSITY

The following tables provide examples of the characteristics of nonwoven filters of the invention (in particular, the volume density is calculated for different circumferences and different sheet widths).

1. Super Slim nonwoven filter: a) Example 1:

b) Example 2:

2. Slim nonwoven filter: a) Example 1:

b) Example 2:

3. King size nonwoven filter:

FILTER PRESSURE DROP

The following tables provide examples of the pressure drop of the nonwoven filters of the invention according to different circumferences (i.e. filter formats). 1. Super slim filter:

2. Slim filter:

3. King size filter:

The filter of the invention may comprise a capsule containing flavourant such as menthol and the like. The encapsulated flavourant may have a core comprising liquid, powder or gel encapsulated by a shell, sheet or coating forming a barrier material. The encapsulated flavourant can be a capsule which can be ruptured to release the flavourant before or during use. The barrier material maybe frangible or breakable. The capsule can be crushed or otherwise fractured or broken by the user to release the encapsulated flavourant. Typically, the capsule is broken immediately prior to smoking or heating being initiated. The term "breakable capsule" refers to a capsule, wherein the shell can be broken by means of a pressure to release the core; more specifically the shell can be ruptured under the pressure imposed by the user's fingers (or any other pressure creating means) when the user wants to release the core of the capsule.

The filter may comprise additives such as charcoal substrate. The substrate may be embedded in the nonwoven material. The charcoal maybe added as particles or beads. The charcoal may be sprayed on the filter paper with binder to make it impregnate the nonwoven substrate. The substrate obtained after spraying the filter paper is an impregnated charcoal substrate. With this method, the charcoal in the impregnated charcoal nonwoven may be normal activated carbon. A filter assembly may be formed of more than one filter of the invention. For example, several segments of filters are arranged sequentially. The segment may have the same composition or a different composition. For instance, a first segment may comprise an encapsulated flavourant and a second segment may comprise additives (e.g., charcoal substrate) or no additive. Filter segments may be adjacent one another (i.e., abutting) or may be separated by a cavity formed by a paper tube and/or a paper wrapper. The cavity may contain an encapsulated flavourant as aforementioned.

A filter of the invention may be positioned at the upstream end of an aerosol generating article or smoking article, for example, as described in EP3861868A1. The filter may be used in a cigarette, an e-cigarette, a vaporizing device, or other known smoking/ aerosol generating articles known in the art. The filter may be used in combustion systems, where an aerosol generating substance is burnt, or heat-not-burn systems, where the aerosol generating substance is heated such that an aerosol is generated from the substance, without burning the substance. The aerosol generating substances may be any substances containing tobacco, nicotine, flavoring agents and/or other substances capable of providing an inhalable aerosol to a user.

Claims

1. A filter for use in a smoking or aerosol generating article, the filter comprising a nonwoven substrate comprising natural fibers and a binder, wherein the natural fibers represent 85% to 95%, preferably, 86.9 to 95% by weight of the nonwoven substrate, and the binder represents 5 to 15%, preferably 5 to 13.1% by weight of the nonwoven substrate, wherein the nonwoven substrate has a dry tensile strength of at least 10 N/scm, preferably at least 12 N/scm and most preferably at least 14 N/scm, and the nonwoven substrate has a thickness from 0.4 to 1.0 mm, preferably from 0.5 to 0.9mm, and most preferably from 0.5 to 0.7 mm.

2. The filter according to the preceding claim, wherein the natural fibers represent from 90 to 93% by weight of the nonwoven substrate, and/or the binder represents from 7 to 10% by weight of the nonwoven substrate.

3. The filter according to any one of the preceding claims, wherein the nonwoven substrate has a volume density of at least 50 mg/cm³, preferably of at least 55 mg/cm³ and most preferably of at least 60 mg/ cm ³, and/ or a volume density of at most 110 mg/cm³, preferably of at most too mg/cm³ and most preferably of at most 90 mg/cm³.

4. The filter according to any one of the preceding claims, wherein the nonwoven substrate has an areal density from 40 to 65 g/m², preferably from 45 to 60 g/m² and most preferably from 46 to 58 g/m².

5. The filter according to any one of the preceding claims, wherein the average length of the natural fibers is at most 3.5 mm, preferably at most 3.0 mm and most preferably at most 2.8 mm, and/ or the average length of the natural fibers is at least 2.0 mm, preferably at least 2.3 mm and most preferably at least 2.5 mm.

6. The filter according to any one of the preceding claims, wherein the natural fibers comprise or preferably consist of wood pulp, the wood pulp preferably being obtained by a kraft process.

7. The filter according to the preceding claim, wherein the wood pulp comprises a soft wood pulp and/ or a hard wood pulp, preferably a Southern bleached softwood kraft, SBSK, and/or a Northern bleached softwood kraft, NBSK, wherein preferably the wood pulp comprises at least 75% SBSK, preferably at least 85% SBSK, more preferably at least 95% SBSK and most preferably 100% SBSK and/or preferably 25% NBSK or less, more preferably 5% NBSK or less.

8. The filter according to any one of the preceding claims, wherein the binder comprises at least one binding agent being a water-based polymer emulsion, preferably solvable in water.

9. The filter according to any one of the preceding claims, wherein the binder comprises one or more of an aqueous copolymer dispersion of Ethylene Vinyl Acetate, EVA, and a Polyvinyl Acetate, PVAc, adhesive.

10. The filter according to the preceding claim, wherein the binder comprises a combination of EVA and PVAc adhesive, wherein the ratio of EVA to PVAc adhesive is preferably between 70:30 and 30:70, more preferably between 60:40 and 40:60 and most preferably between 55:45 and 45:55.

11. The filter according to any one of claims 9 or 10, wherein the PVAc adhesive is a Polyvinyl alcohol stabilized polyvinyl acetate, preferably stabilized by a vinyl alcohol polymer, PVOH, a dextrin, or combinations thereof, wherein the EVA is stabilized with one or more of a surfactant, an emulsifier, a cellulose derivate, PVOH, a colloid, and combinations thereof.

12. The filter according to any one of the preceding claims, wherein the nonwoven substrate is crimped in the machine direction with a crimping depth of 0.2 to 1.0 mm, preferably of 0.5 to 0.9 mm.

13. The filter according to any one of the preceding claims, wherein the filter has a density of too to 200 mg/cm³, and/or wherein the pressure drop at the filter is between 1.3 and 4.5 mmWC/mm, preferably between 1.8 and 3 mmWC/mm, preferably determined according to the conditions described in 1806565:2015.

14- The filter according to any one of the preceding claims, wherein the nonwoven substrate is brought in a rod-shaped form and is wrapped by a wrapping paper having a basis weight of 25 to 50 gsm, and/or a thickness of 0.03 to 0.06 mm.

15. The filter according to any one of the preceding claims, wherein the natural fibers represent at least 86% by weight of the nonwoven substrate, preferably at least 87% by weight of the nonwoven substrate, more preferably at least 88% by weight of the nonwoven substrate, and most preferably at least 89% by weight of the nonwoven substrate, and/ or at most 95% by weight of the nonwoven substrate, preferably at most 94% by weight of the nonwoven substrate, and most preferably at most 93% by weight of the nonwoven substrate, and/or the binder represents at most 14% by weight of the nonwoven substrate, preferably at most 13% by weight of the nonwoven substrate, more preferably at most 12% by weight of the nonwoven substrate, and most preferably at most 11% by weight of the nonwoven substrate, and/or at least 5% by weight of the nonwoven substrate, preferably at least 6% by weight of the nonwoven substrate, and most preferably at least 7% by weight of the nonwoven substrate.

16. An aerosol generating article, preferably a cigarette or heat-not-burn aerosol generating article comprising a filter according to any one of the preceding claims.

17. A method for manufacturing of a filter according to any one of claims 1 to 16 for use in a smoking or aerosol generating article, comprising the steps of: providing a nonwoven substrate arranged as a festoon on a bale or pallet; inserting the nonwoven substrate into a manufacturing facility for manufacturing of the filter; and crimping the nonwoven substrate into the filter.