Filter for aerosol-generating article

Abstract

The present invention relates to a filter for use in a smoking or aerosol-generating article and an aerosol-generating article comprising the filter. The filter comprises a non-woven substrate comprising natural fibers and a binder wherein the natural fibers comprise 85% to 95%, preferably 86.9% to 95%, by weight of the non-woven substrate, and the binder comprises 5% to 15%, preferably 5% to 13.1%, by weight of the non-woven 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 0.4 to 1.0 mm, preferably 0.5 to 0.9 mm and most preferably 0.5 to 0.7 mm.

Description

TECHNICAL FIELD

[0001] The present 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 non-woven matrix comprising natural fibres and an adhesive. BACKGROUND ART

[0002] In the past few years, smoking articles such as cigarettes have been equipped with acetate filters to filter out unhealthy components from the aerosol inhaled by the user. However, when discarded, used cigarettes and especially the filters typically end up in the environment, which can be harmful to the environment. Due to the increasing environmental awareness of consumers, replacing commonly used non-biodegradable filters with biodegradable filters containing natural materials is becoming an increasingly sought-after goal for manufacturers.

[0003] For example, GB 2525363 A discloses a biodegradable cigarette filter tow comprising a mixture of at least two or more natural materials and a natural adhesive selected from the group consisting of hemp fibres, flax fibres, abaca fibres or pulp, sisal fibres or pulp, wood pulp or cotton fibres or linters.

[0004] WO 2022 / 053621 relates to a filter comprising a non-woven matrix having a low density and comprising natural fibres and an adhesive, wherein the filter can be used as a filter for smoking or inhalation articles.

[0005] Although the prior art discloses filters comprising natural non-woven materials, due to the low density of the filter, the non-woven matrix may rupture during filter manufacture, especially during / after the crimping process commonly used for filter production of sheet matrices, and the filter has a risk of shedding, which may result in an unpleasant smoking experience for the user. In addition, during the production of the non-woven matrix, the adhesive tends to leak out of the non-woven matrix, contaminating the manufacturing machine, which reduces the yield of filter production.

[0006] Therefore, it is desirable to provide a filter that can be manufactured to have a reduced risk of rupture during production, a reduced risk of shedding during use and a reduced risk of adhesive leakage during the production of the non-woven matrix. It is desirable to provide a method for manufacturing such a filter. SUMMARY OF THE INVENTION

[0007] The present invention provides a filter having a non-woven matrix comprising natural fibres and an adhesive, the filter solving some or all of the above problems.

[0008] The first embodiment of the present invention relates to a filter for use in a smoking or aerosol - generating article, the filter comprising a non - woven matrix comprising natural fibers and an adhesive, wherein the natural fibers account for 85% to 95% by weight, preferably 86.9% to 95% by weight, of the non - woven matrix, and the adhesive accounts for 5% to 15% by weight, preferably 5% to 13.1% by weight, of the non - woven matrix, wherein the non - woven matrix 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 non - woven matrix has 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. Preferably, the natural fibers account for more than 85% to 90% by weight of the non - woven matrix and the adhesive accounts for 5% to less than 15% by weight of the non - woven matrix.

[0009] Filters made from non - woven matrices with a tensile strength below 10 N / 5 cm have an increased risk of matrix rupture during manufacture or upon shedding due to the low tensile strength. The above compositions produce filters made from natural materials that are durable and have inhalation and nicotine retention characteristics similar to those of filters known in the art to which consumers are accustomed. Additionally, leakage of the adhesive from the non - woven matrix during manufacture is reduced.

[0010] According to a second embodiment, in the previous embodiment, the natural fibers account for 90% to 93% by weight of the non - woven matrix, and / or the adhesive accounts for 7% to 10% by weight of the non - woven matrix.

[0011] Preferably, the natural fibers account for 91% to 95% by weight of the non - woven matrix, and / or the adhesive accounts for 5% to 9% by weight. More preferably, the natural fibers account for 93% to 95% by weight of the non - woven matrix, and / or the adhesive accounts for 5% to 7% by weight. The reduced amount of adhesive provides improved biodegradability.

[0012] Furthermore, in any of the foregoing embodiments, the natural fibers account for at least 86% by weight of the non - woven matrix, preferably at least 87% by weight of the non - woven matrix, more preferably at least 88% by weight of the non - woven matrix and most preferably at least 89% by weight of the non - woven matrix, and / or at most 95% by weight of the non - woven matrix, preferably at most 94% by weight of the non - woven matrix and most preferably at most 93% by weight of the non - woven matrix, and / or the adhesive accounts for at most 14% by weight of the non - woven matrix, preferably at most 13% by weight of the non - woven matrix, more preferably at most 12% by weight of the non - woven matrix and most preferably at most 11% by weight of the non - woven matrix, and / or at least 5% by weight of the non - woven matrix, preferably at least 6% by weight of the non - woven matrix and most preferably at least 7% by weight of the non - woven matrix.

[0013] According to the third embodiment, in any of the foregoing embodiments, the nonwoven substrate has a bulk density of at least 50 mg / cm 3 , preferably at least 55 mg / cm 3 and most preferably at least 60 mg / cm 3 , and / or at most 140 mg / cm3, preferably at most 130 mg / cm3, even more preferably at most 120 mg / cm3, preferably at most 110 cm 3 , or at most 100 mg / cm 3 or at most 90 mg / cm 3 .

[0014] According to the fourth embodiment, in any of the foregoing embodiments, the nonwoven substrate has a basis weight of 40 to 65 g / m 2 , preferably 45 to 60 g / m 2 and most preferably 46 to 58 g / m 2 .

[0015] By the above embodiments, the risk of adhesive leakage can be further reduced.

[0016] According to the fifth embodiment, in any of the foregoing 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.

[0017] According to the sixth embodiment, in any of the foregoing embodiments, the natural fibers comprise or preferably consist of wood pulp, which is preferably obtained by the kraft process.

[0018] According to the seventh embodiment, in the previous embodiment, the wood pulp comprises softwood pulp and / or hardwood pulp, preferably southern bleached softwood kraft pulp SBSK and / or northern bleached softwood kraft pulp 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.

[0019] Using natural fibers reduces the negative environmental impact of the filter. In addition, the non-woven matrix made of wood pulp provides filtration capabilities (pressure drop and nicotine retention characteristics) similar to those of filters known in the art. Thus, the negative environmental impact of the filter can be reduced while maintaining similar filtration capabilities. In addition, a higher percentage of SBSK tends to reduce the pressure drop of the filter compared to a higher percentage of NBSK. Therefore, the ratio of SBSK to NBSK can be used to adjust the pressure drop of the filter.

[0020] According to the eighth embodiment, in any of the foregoing embodiments, the binder comprises at least one binding agent that is an aqueous polymer emulsion, preferably water-soluble.

[0021] According to the ninth embodiment, in any of the foregoing embodiments, the binder comprises one or more of an aqueous copolymer dispersion of ethylene vinyl acetate EVA and polyvinyl acetate PVAc binders.

[0022] According to the tenth embodiment, in the previous embodiment, the binder comprises a combination of EVA and PVAc binders, wherein the ratio of EVA to PVAc binder 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.

[0023] According to the eleventh embodiment, in the ninth or tenth embodiment, the PVAc binder is a polyvinyl alcohol-stabilized polyvinyl acetate, preferably stabilized by a vinyl alcohol polymer, PVOH, dextrin, or a combination thereof, wherein the EVA is stabilized by one or more of a surfactant, an emulsifier, a cellulose derivative, PVOH, a colloid, and a combination thereof.

[0024] The above binders and water-soluble binders generally increase the degradation rate of the filter in the environment. That is, if exposed to rain or soil, the water-soluble binder dissolves and the filter is more likely to fall off, which in turn accelerates the natural degradation of the filter.

[0025] According to the twelfth embodiment, in any of the foregoing embodiments, the non-woven matrix comprises a flavor additive.

[0026] Adding a flavor additive to the filter improves the consumer experience. In particular, the flavor additive can mask the taste of the natural fiber material contained in the filter.

[0027] According to the thirteenth embodiment, in any of the foregoing embodiments, the reel width of the non-woven matrix is between 50 and 240 mm, preferably between 100 and 220 mm, for example between 120 and 180 mm.

[0028] The width of the reel can depend on the perimeter of the filter. The smaller the perimeter, the narrower the width. More particularly, when the perimeter of the filter is about 16.8 mm ("ultra - fine" type), the width of the reel is preferably between 50 and 100 mm. When the perimeter of the filter is about 21.5 mm ("fine" type), the width of the reel is preferably between 100 and 160 mm. When the perimeter of the filter is about 24.2 mm ("large" type), the width of the reel is preferably between 120 and 180 mm.

[0029] According to the fourteenth embodiment, in any of the foregoing embodiments, the non - woven substrate is crimped in the machine direction with a crimp depth of 0.2 to 1.2 mm, preferably 0.2 to 1.0 mm, more preferably 0.5 to 1.0 or 0.5 to 0.9 mm.

[0030] The crimp depth within the above range reduces the risk of unwanted cracks in the non - woven substrate while achieving the desired crimping effect.

[0031] According to the fifteenth embodiment, in any of the foregoing embodiments, the filter has a density between 100 and 220 mg / cm 3 or between 100 and 200 mg / cm 3 such as 140 mg / cm 3 and / or the pressure drop across 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 ISO6565:2015.

[0032] According to the sixteenth embodiment, in any of the foregoing embodiments, preferably when subjected to a pressure of 350 g for 5 seconds in the SODIM - H hardness measurement module, the hardness of the filter corresponds to a reduction in the diameter of the filter within the range of 2.5 mm to 1.3 mm, more preferably within the range of 2.3 mm to 1.5 mm.

[0033] The pressure drop within the above range is similar to that of a conventional cellulose acetate filter. Thus, a user consuming a smoking article / aerosol - generating device having the filter has a desired consumption experience.

[0034] According to the seventeenth embodiment, in any of the foregoing embodiments, the non - woven substrate is in the form of a rod and is wrapped with a wrapper paper having a basis weight of 24 to 120 gsm or 25 to 50 gsm, preferably 27 to 45 gsm and / or a thickness of 0.03 to 0.13 mm or 0.03 to 0.06 mm, preferably 0.043 to 0.125 mm.

[0035] For example, the perimeter can be between 16 and 28 mm, such as 16.8 mm, or approximately between 16 and 26 mm, such as 21.5 mm, or approximately between 16.8 and 24.20 mm.

[0036] According to the eighteenth embodiment, in the previous embodiment, the perimeter of the filter is between 16 and 28 or between 20 and 28 mm, preferably between 22 and 26 mm, even more preferably between 24 and 25 mm, and most preferably 24.2 mm.

[0037] The above ranges are commonly used in state-of-the-art smoking articles / aerosol generating devices. Therefore, filters within the above ranges can be used for various applications.

[0038] The nineteenth embodiment relates to an aerosol generating article, preferably a cigarette or a heat-not-burn aerosol generating article, which includes a filter according to any one of the previous embodiments.

[0039] The twentieth embodiment relates to a method for manufacturing a filter including a non-woven substrate for use in a smoking or aerosol generating article, preferably a filter according to any one of the first to eighteenth embodiments, the method comprising the steps of: providing a non-woven substrate arranged as a continuous sheet on a bale or pallet (also referred to herein as a "festoon"), inserting the non-woven substrate into a production facility to produce the filter, and curling the non-woven substrate into the filter.

[0040] Preferred embodiments will now be described by way of example only with reference to the accompanying drawings. Description of the Drawings

[0041] Figure 1 : is a graph showing the tensile strength measurement results of an exemplary non-woven substrate at different thicknesses and binder contents;

[0042] Figure 2 : is another graph showing the tensile strength measurement results of an exemplary non-woven substrate at different thicknesses and binder contents;

[0043] Figure 3 : is a graph of the robustness of an exemplary filter including a non-woven substrate versus the pressure drop;

[0044] Figure 4a : shows the arrangement of the non-woven material according to the first embodiment;

[0045] Figure 4b : shows the arrangement of the non-woven material according to the second embodiment;

[0046] Figure 5: shows the space requirements for non-woven substrates stored on bales / pallets by a folding and stacking process, as well as the space requirements for non-woven substrates supplied in rolls, i.e., by a known rolling process. Detailed Description

[0047] Preferred embodiments of the present invention are described below with reference to the accompanying drawings.

[0048] Hereinafter, filters including non-woven substrates for use in smoking or aerosol generating articles are described in more detail.

[0049] A non-woven substrate refers to a substrate made of fibrous material, where the fibers are bonded together mechanically, chemically, or by an adhesive, and is well-known in the art.

[0050] The filter according to an embodiment includes a non-woven substrate containing natural fibers and an adhesive. Preferably, the non-woven substrate is provided as a sheet. In the non-woven substrate, the natural fibers account for 85% to 95% by weight of the non-woven substrate and the adhesive accounts for 5% to 15% by weight of the non-woven substrate. Preferably, the natural fibers account for more than 85% to 90% by weight of the non-woven substrate and the adhesive accounts for 5% to less than 15% by weight of the non-woven substrate.

[0051] To avoid rupture of the non-woven substrate during filter production and / or detachment of the filter including the non-woven substrate, a non-woven substrate having 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 / 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 is used. Filters including such non-woven substrates have proven to be particularly anti-detachment and are produced at a high yield. According to EN ISO 9073-2:1996 "Test methods for nonwovens", the thickness of the non-woven substrate is measured by applying a pressure of 0.5 kPa on a specimen with a pressing surface area of 25 cm 2 of the specimen.

[0052] In some embodiments, the natural fibers account for 90% to 93% by weight of the non-woven substrate, and / or the adhesive accounts for 7% to 10% by weight of the non-woven substrate. More preferably, the natural fibers account for between more than 90% and 93% by weight of the non-woven substrate, and the adhesive accounts for between 7% and less than 10% by weight of the non-woven substrate.

[0053] In some embodiments, the non-woven substrate has at least 50 mg / cm 3 、preferably at least 55 mg / cm 3 and most preferably at least 60 mg / cm3 The bulk density (also known as sheet density), and / or at most 140 mg / cm 3 , preferably at most 130 mg / cm 3 and even more preferably at most 120 mg / cm 3 and most preferably at most 110 mg / cm 3 preferably at most 100 mg / cm 3 and most preferably at most 90 mg / cm 3 of the bulk density.

[0054] The bulk density of the nonwoven substrate can be obtained by dividing the areal density or grammage of the substrate by its thickness.

[0055] In some embodiments, the nonwoven substrate has an areal density (also known as grammage) of 40 to 65 g / m 2 , preferably 45 to 60 g / m 2 and most preferably 46 to 58 g / m 2 of the areal density.

[0056] The areal density of the sheet of the nonwoven substrate is determined by placing the sheet on a balance and measuring the weight. Thereafter, the weight is divided by the area of the sample and the areal density / grammage is obtained. For example, standard ISO 536:2019 can be used to determine the areal density of the nonwoven substrate.

[0057] For a given length, the higher the areal density / bulk density of the nonwoven material, the higher the pressure drop of the filter made using the nonwoven material.

[0058] The natural fiber material for the nonwoven substrate can be selected from one or more of the following: wood fiber, cotton fiber, leaf fiber (such as abaca or sisal fiber), bast fiber (such as jute, hemp, flax or kenaf fiber) and / or semi-natural fiber (such as viscose and / or lyocell fiber). Although the natural fiber can be selected from any of the above, in some embodiments, it is desirable to select a natural fiber with particularly good biodegradability so that environmental friendliness can be improved.

[0059] For example, the natural fiber can comprise or preferably consist of wood fiber selected from softwood pulp or hardwood pulp or a combination thereof. Preferably, the natural fiber comprises at least 50%, more preferably at least 70%, even more preferably at least 90%, even more preferably at least 95% and most preferably 100% of wood fiber. Preferably, the pulping process is kraft pulping process and the natural fiber is southern bleached softwood kraft pulp SBSK and / or northern bleached softwood kraft pulp 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 (by weight percentage).

[0060] According to some 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.

[0061] An exemplary SBSK material suitable for filters is GoldenIsles treated fluff (grade 4623). The material has a fiber length of 2.68 mm and a basis weight of 765 g / m 2 ².

[0062] The binder added to the natural fibers to form the nonwoven matrix may comprise at least one binding agent which is an aqueous polymer emulsion, preferably water-soluble. The binder may be selected from one or more of the following: aqueous copolymer dispersions of ethylene vinyl acetate EVA and polyvinyl acetate PVAc binders, cellulose derivatives such as ethyl / methyl cellulose, hydroxyethyl / hydroxymethyl cellulose and / or carboxymethyl cellulose, and / or polysaccharides (or derivatives of polysaccharides) such as dextrin or starch.

[0063] In some embodiments, the binder is selected from one or more of the aqueous copolymer dispersions of ethylene vinyl acetate EVA and polyvinyl acetate PVAc binders. Preferably, the ratio of EVA to PVAc binder 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 binder is 50:50. One benefit of these binders is that they have no negative impact on phenol delivery.

[0064] The PVAc binder may be PVAc (vinyl alcohol polymer) stabilized by PVOH, dextrin and combinations thereof, more preferably the PVAc binder stabilized by PVOH. The advantages of the PVAc binder are its high adhesion characteristics to natural fibers, the rapid setting of the binder, and its compatibility with the EVA dispersion. An exemplary polyvinyl alcohol-stabilized polyvinyl acetate (PVAc) binder is Vinamul 8482 commercialized by Celanese Corporation.

[0065] Exemplary copolymers of EVA are copolymers of EVA stabilized with surfactants, emulsifiers, cellulose derivatives, PVOH, colloids and combinations thereof. The copolymer is hydrophilic such that it can easily wet the fiber material and has good adhesion characteristics. Preferred is the copolymer of EVA in an aqueous copolymer dispersion which has self-crosslinking characteristics based on vinyl acetate and ethylene stabilized with a surfactant. The copolymer provides a particularly neutral taste and has a low volatile organic compound (VOC) content.

[0066] For the production of filters from nonwoven sheets, the nonwoven sheets preferably have a reel width of 50 to 240 mm or 100 to 220 mm, preferably 70 to 170 or 120 to 180 mm.

[0067] Preferably, the nonwoven substrate is preferably stored on one or more bales / pallets by a folded stacking process. In other words, the nonwoven material can be stored as a continuous sheet, also indicated herein by the term "folded stacking", preferably forming a bale. The continuous sheet of nonwoven material or the bale formed from the continuous nonwoven material can be arranged on a pallet or similar support. It must be noted that the term "continuous sheet" is used herein to indicate both a single continuous sheet made as one piece and a sheet composed of joined sections of nonwoven sheets. In other words, two or more sections of nonwoven material can be joined together to form a continuous sheet. For example, the rolls currently used in the art can be joined together to form a continuous sheet of nonwoven material. For example, the material of two or more rolls (such as 10 rolls) can be "converted", i.e., arranged as a continuous sheet stored on a bale / pallet.

[0068] Below, the folded stacking process for storing the nonwoven substrate, i.e., for storing the nonwoven substrate on bales and / or pallets, and the method for supplying the nonwoven substrate from the bales / pallets to a filter manufacturing device for the production of filters are described in more detail.

[0069] 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 described above, the continuous sheet of nonwoven material or the bale formed from the continuous nonwoven material can be arranged on a pallet or similar support.

[0070] One such example is shown in Figure 4aAmong them, adjacent segments (401a, 401b, 401c) of the continuous nonwoven sheet are arranged adjacent to each other in a substantially horizontal direction H, wherein the adjacent segments (401a, 401b, 401c) can partially overlap. The nonwoven substrate is arranged on a tray or bale such that during removal of the nonwoven substrate from the tray or bale, the separate first layer of the nonwoven substrate is removed before the separate second layer below the separate first layer of the nonwoven substrate is removed from the tray or bale. Further, the nonwoven substrate is arranged on a tray or bale such that the segments (401a, 401b, 401c) forming separate layers of the nonwoven substrate are removed from the tray or bale in a substantially horizontal direction H. Additionally, each of the separate layers of the nonwoven material can extend over the total area of the tray or bale. A nonwoven substrate provided as described above, preferably arranged by a folding and stacking process (which can be carried out at the same equipment for producing the filter or can be carried out at a different equipment before producing the filter), is used for producing a filter in a direction P. It must be noted that the folding and stacking process for producing the bale is preferably carried out in, for example, the nonwoven process equipment of a nonwoven fabric supplier, but it does not exclude that the folding and stacking process for producing the bale can be carried out at the same equipment for producing the filter.

[0071] In a second embodiment, the nonwoven substrate is provided on a tray and / or bale, wherein separate stacks (420a, 420b) of the nonwoven material are arranged adjacent to each other. As described above, a continuous sheet of the nonwoven material or a bale formed of continuous nonwoven material can be arranged on a tray or a similar support. One such example is shown in Figure 4bIn this example, adjacent segments (402a, 402b) of the continuous nonwoven sheet are arranged one above / below the other in a substantially vertical direction V, where the adjacent segments can substantially completely overlap. While in the previous example, adjacent segments (402a, 402b) of the continuous nonwoven sheet were arranged adjacent to each other to form separate layers, in this example, adjacent segments (402a, 402b) of the continuous nonwoven sheet are arranged one above / below the other to form separate stacks (420a, 420b) of the nonwoven substrate. The nonwoven substrate is arranged on a tray or bale such that during removal of the nonwoven substrate from the tray or bale, the separate first stack (420a) of the nonwoven substrate is removed before the separate second stack (420b) adjacent to the separate first stack (420a) of the nonwoven substrate is removed from the tray or bale. Further, the nonwoven substrate is arranged on a tray or bale such that the segments (402a, 402b) forming the separate stacks (420a, 420b) of the nonwoven substrate are removed from the tray or bale in a substantially vertical direction V. Further, each of the separate stacks (420a, 420b) of the nonwoven material can extend over the total height of the nonwoven substrate arranged on the tray or bale. A nonwoven substrate preferably arranged by a folding and stacking process as described above is provided for producing a filter in direction P. It must be noted that the folding and stacking process for producing the bale is preferably carried out in a nonwoven processing device of a nonwoven supplier, for example, but it is not excluded that the folding and stacking process for producing the bale can be carried out at the same device where the filter is produced.

[0072] Compared to other widely used arrangements such as a rolling process where the nonwoven sheet is arranged on one or more reels, providing a nonwoven substrate stored in the form of a bale and / or stored on a tray using a folding and stacking process has the advantage of reduced area requirements in the production facility.

[0073] In Figure 5 is shown the difference in space requirements between a rolling process [a] for manufacturing a filter and the feeding of a nonwoven substrate stored in a bale / tray by a folding and stacking process [b]. Generally, in the rolling process [a], at least two large reels (501) are provided for feeding the nonwoven substrate to the production facility. Generally, before the nonwoven substrate is transferred into the coiling unit (510), the nonwoven substrate is fed from the reel (501) into a buffer (502). When a reel needs to be replaced, its rotational movement must be stopped and the buffer allows splicing of the nonwoven substrate from the currently used reel to the subsequent reel while allowing the manufacturing process of the filter to continue without interruption.

[0074] In contrast, when the nonwoven substrate has been stored in bales / trays by a folded stacking process [b], the nonwoven substrate provided on the bale or tray (503) can be directly fed (pulled from the bale / tray) into a filter manufacturing process, such as its coiling unit (510), for producing filters. Since the nonwoven substrate is provided on the bale or tray, the buffer for splicing the substrate in the folded stacking process is at least reduced, or in some embodiments not necessary. In fact, the nonwoven substrate can be connected from the currently used bale / tray to the front end of the nonwoven substrate of the subsequent bale / tray to be used before the tail end of the nonwoven substrate of the currently used bale / tray is fed into the coiling unit. In other words, since the tail end of the nonwoven substrate is always available, the splicing of the nonwoven substrates of two bales / trays can be easily performed, which is contrary to the reel arrangement, in which the nonwoven substrate rotates and thus the operation on the nonwoven substrate or on the reel requires stopping its rotational movement.

[0075] This also results in a significantly smaller space requirement in the production facility when compared to the space required for the rolling process. In this regard, it must be noted that the folded stacking process allows the storage of nonwoven substrates having a length that is typically stored in about 10 reels in the prior art on a bale.

[0076] Advantageously, the folded stacking process for storing nonwoven substrates, for example in the form of bales, allows the provision of biodegradable filters containing nonwoven materials, which have a layout in the production facility similar to that of conventional filters (such as cellulose acetate filters), while providing less space requirements and a more efficient exchange of subsequent feed bales / trays, which do not require (or at least reduce) the buffer for compensating for the interruption of reel rotation required in the prior art.

[0077] To improve the quality of the filters obtained from the nonwoven substrate, in an exemplary embodiment, the nonwoven substrate is coiled before being formed into a filter. In this exemplary embodiment, the nonwoven substrate is coiled in the machine direction of the coiling machine with a coiling depth of 0.2 to 1.2 or 0.2 to 1.0 mm, preferably 0.5 to 1.0 mm or 0.5 to 0.9 mm, to obtain straight coiling grooves. The above ranges provide good filtration characteristics without causing any breakage and cracks in the nonwoven substrate.

[0078] Although the coiling process can improve the filtration quality, for some embodiments, this additional step can be removed from the manufacturing process, and the filter can be directly formed from the nonwoven substrate.

[0079] Then, the curled non-woven substrate can be wound from the sheet into a typical cylindrical filter shape / rod shape by winding the sheet around the longitudinal axis of the filter. In other embodiments, the curled non-woven substrate is pressed into a typical cylindrical filter shape / rod shape. Although cylindrical / rod-shaped filters are the most common in the art, the curled non-woven substrate can also have a rectangular shape, a conical shape, a spherical shape, or any other shape that fits into the smoking article / aerosol generating device in which it is used.

[0080] Additionally, flavorants can be added to the filter to provide a more enjoyable smoking experience for the user.

[0081] To be compatible with commonly used smoking articles / aerosol generating devices, the perimeter of the filter (including the filter wrapper thickness) is preferably between 16 and 28 mm or between 20 and 28 mm, more preferably between 22 and 26 mm, even more preferably between 24 and 25 mm, and most preferably 24.2 mm. For example, the perimeter can be between 16 and 28 mm such as 16.8 mm, or about 16 to 26 mm such as 21.5 mm, or about 16.8 to 24.20 mm.

[0082] To allow for handling and accommodation of the filter matrix, the wound non-woven substrate can be wrapped with a wrapper paper having a basis weight of 24 to 120 gsm or 25 to 50 gsm, or 27 to 100 gsm and / or a thickness of 0.03 to 0.125 mm or 0.03 to 0.06 mm. For example, a filter rod forming paper of 0.100 mm or 0.110 mm or 0.120 mm can advantageously provide improved filter hardness.

[0083] Preferably, the filter obtained with the above materials has a density of 100 to 200 mg / cm 3 、preferably between 120 and 160 mg / cm 3 、such as 150 mg / cm 3 , where the pressure drop across 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 can vary according to the perimeter of the filter. For example, when the filter perimeter is about 16.8 mm, the filter density can be between 106 and 211 mg / cm 3 , where the pressure drop is between 2.78 and 4.44 mmWC / mm. When the filter is about 21.5 mm, the filter density can be between 130 and 208 mg / cm 3 , where the pressure drop is between 2.04 and 3.70 mmWC / mm. When the filter is about 24.2 mm, the filter density can be between 123 and 184 mg / cm3 between 1.67 and 4.44 mmWC / mm.

[0084] Exemplary nonwoven substrates

[0085] In the following, working examples of nonwoven substrates are discussed in detail. Table 1 shows four samples (batches 2, 4, 7, and 8) of nonwoven substrates manufactured considering the above characteristics.

[0086] Batches 2, 4, 7, and 8 were manufactured with fiber contents in the range of 86.9% to 91.8% and corresponding binder contents in the range of 8.2% to 13.1%. From these four samples, batch 4 has the lowest binder content of 8.2%, followed by batch 7 at 8.5%, then batch 2 with a binder content of 9.5%, and batch 8 with the highest binder content of 13.1%.

[0087] For each sample, the areal density, thickness, and dry tensile strength were measured. To measure the tensile strength, a 5 cm strip of the corresponding nonwoven substrate was cut and clamped in a tensile strength measuring device. For example, a Zwick Roell tensile strength measuring device can be used, where the tensile strength is preferably measured under the test conditions defined in ISO 9073-3. However, other methods are also possible, such as the measuring method defined in ISO 9073-18:2007. In this particular example, the measuring method defined in ISO 9073-3 was carried out. The tensile strength measuring device applied a force to each end of the 5 cm strip until the breaking point of the strip was reached and it tore / broke. Then the force required and the elongation of the strip were measured.

[0088] The following Table 1 shows the measurement results regarding the density, thickness, and tensile strength of the corresponding samples (batches 2, 4, 7, and 8). The sheet density was calculated by dividing the areal density by the thickness.

[0089] Table 1

[0090]

[0091] As can be seen from Table 1, the areal density of the samples is in the range of 44.4 to 81.63 mg / cm 3 The nonwoven substrate of batch 7 has the lowest areal density of 46.99 g / m 2 , followed by batch 4 with an areal density of 50.61, then batch 8 with an areal density of 55.58 g / m 2 , and batch 2 has the highest areal density of 55.58 g / m 2 .

[0092] The corresponding thickness of the samples ranges from 0.62 to 1.19 mm. From these four samples, Batch 4 has the lowest thickness of 0.62 mm, followed by Batch 7 with a thickness of 0.78 mm, then Batch 2 with a thickness of 0.92 mm, and Batch 8 with a thickness of 1.19 mm.

[0093] The tensile strength measured for the samples ranges from 14.2 to 28.2. From these four samples, Batch 7 has the lowest tensile strength of 14.2 N / 5 cm, followed by Batch 8 with a tensile strength of 14.7 N / 5 cm, then Batch 2 with a tensile strength of 18.0 N / 5 cm, and Batch 4 with the highest tensile strength of 28.2 N / 5 cm.

[0094] As shown above, generally a high volume / sheet density of the nonwoven fabric results in a high tensile strength of the material. However, the tensile strength of the filter also depends on the amount of binder and the thickness of the material. This can be seen from Table 1, where Batches 2 and 7 have similar volume densities, but the tensile strengths vary significantly.

[0095] To show the influence of specific parameters on the tensile strength, samples of the second and third batches were prepared. In Figure 1 and Figure 2 the tensile strengths of the corresponding samples of the second and third batch nonwoven substrates are shown relative to the corresponding thickness and binder content of the samples. In Figure 1 the substrates in regions 1 and 4 show tensile strengths sufficient for filter production, the substrates in region 2 show tensile strengths somewhat sufficient for filter production, and the substrates in region 3 show tensile strengths insufficient for filter production as they have an increased risk of tearing. Similarly, in Figure 2 region 1 shows substrates with sufficient tensile strength, region 2 shows substrates with somewhat sufficient tensile strength, and region 3 shows substrates without sufficient tensile strength for filter production.

[0096] In particular, as can be seen from Figure 1 if the areal density and 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 the tensile strength increases as the volume density increases. Additionally, if the thickness and thus the sheet / volume density are kept constant, the tensile strength increases with the binder content. Thus, the areal density, thickness, and binder content of the nonwoven fabric all directly affect the resulting tensile strength.

[0097] Returning to the samples of Table 1, although each sheet of the nonwoven substrate from each of batches 2, 4, 7, and 8 showed sufficient tensile strength for filter production, the production rates of batches 7 and 8 were lower compared to batches 2 and 4. This is because during production, a large amount of adhesive leaked from the substrate, which contaminated the machines used to produce the nonwoven sheets. This in turn led to a reduced production rate because additional cleaning processes had to be added to the operations of batches 7 and 8.

[0098] The amount of adhesive leaking from the nonwoven substrate also depends on the adhesive content, the thickness of the material, the surface density, and thus also on the sheet / volume density. For example, a low volume density that hardly prevents the escape of adhesive from the nonwoven material increases the amount of adhesive leaking from the device. Similarly, increasing the adhesive content while the other parameters are constant also increases the amount of adhesive leaking from the nonwoven substrate. Additionally, if the adhesive content and volume density are constant, a lower thickness increases the effect of leakage because less textile material is provided to prevent the adhesive from leaking.

[0099] Therefore, while the parameters affecting tensile strength indicate that a high adhesive content is desirable, leakage also increases with a high adhesive content, which is to be prevented. Additionally, too low a thickness requires high pressure during production, which results in an uneven web of nonwoven material. Thus, nonwoven substrates having a relatively low thickness in the range of 0.5 to 0.7 mm (high sheet / volume density) and / or having a relatively low adhesive content in the range of 10% - 7% are most preferred.

[0100] Filtration characteristics

[0101] Filters were formed from the nonwoven sample materials as described above by curling a sheet of the nonwoven material, winding the curled sheet into a rod shape, and wrapping the rod-shaped nonwoven sheet with wrapping paper.

[0102] Then, the obtained filters were subjected to pressure drop and firmness / hardness measurements to determine whether the filters obtained according to the above method showed filtration characteristics similar to those of filters known in the art.

[0103] The firmness / hardness and pressure drop of the filters were measured using the hardness module (SODIM-H) and the pressure drop module (SODIM-PDVM) of the Sodiline measuring 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 started, and the pressure drop (in mmWC) at the filter was measured. In the hardness module, the jaws were moved to apply pressure to the side of the filter (in the axial direction of the cylindrical filter) and the amount of compression (the amount of deformation in tenths of a mm) was recorded.

[0104] Figure 3 The corresponding test results of multiple produced filters are shown. The measured pressure drop of the filters is plotted against their corresponding measured hardness. In the measurement, the filters are subjected to a pressure of 350 g weight in SODIM-H for 5 s. It can be seen that the pressure drop at the filter decreases as the firmness of the filter increases. Most preferably, the pressure drop is 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 between 1.8 and 3 mmWC / mm. Therefore, the corresponding firmness of the filter is 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 the filter is prepared as described above.

[0105] Therefore, the filter obtained from the above non-woven material provides a pleasant inhalation experience for the user. In addition, due to the high tensile strength of the material, the rupture of the non-woven sheet is prevented. Moreover, the natural non-woven fibers and preferably the water-soluble binder provide a more environmentally friendly filter.

[0106] Filter density

[0107] The following table provides examples of the characteristics of the non-woven filter of the present invention (in particular, the bulk density is calculated for different circumferences and different sheet widths).

[0108] 1. Ultra-fine non-woven filter:

[0109] a) Example 1:

[0110]

[0111] b) Example 2:

[0112]

[0113]

[0114] 2. Fine non-woven filter:

[0115] a) Example 1:

[0116]

[0117] b) Example 2:

[0118]

[0119]

[0120] 3. Large non-woven filter:

[0121]

[0122] Filter pressure drop

[0123] The following table provides examples of the pressure drop of the nonwoven filters of the present invention according to different perimeters (i.e., filter models).

[0124] 1. Ultra-fine filter:

[0125] Parameter Value Unit Parameter Value Unit Filter length 108 mm Filter length 108 mm Filter PD 300 mmWC / 108mm Filter PD 480 mmWC / 108mm Filter PD 2.78 mmWC / mm Filter PD 4.44 mmWC / mm

[0126] 2. Fine filter:

[0127] Parameter Value Unit Parameter Value Unit Filter length 108 mm Filter length 108 mm Filter PD 220 mmWC / 108mm Filter PD 400 mmWC / 108mm Filter PD 2.04 mmWC / mm Filter PD 3.70 mmWC / mm

[0128] 3. Large filter:

[0129] Parameter Value Unit Parameter Value Unit Filter length 108 mm Filter length 108 mm Filter PD 180 mmWC / 108mm Filter PD 480 mmWC / 108mm Filter PD 1.67 mmWC / mm Filter PD 4.44 mmWC / mm

[0130] The filter of the present invention may include capsules containing flavorants (such as menthol, etc.). The encapsulated flavorant may have a core containing a liquid, powder, or gel, which is encapsulated by a shell, sheet, or coating forming a barrier material. The encapsulated flavorant may be a capsule, which may be broken before or during use to release the flavorant. The barrier material may be fragile or rupturable. The capsule may be crushed or otherwise broken or ruptured by the user to release the encapsulated flavorant. Generally, the capsule ruptures immediately before starting to smoke or heat. The term "rupturable capsule" refers to a capsule in which the shell can be ruptured by pressure to release the core; more specifically, when the user wants to release the core of the capsule, the shell can be broken under the pressure applied by the user's finger (or any other pressure generating device).

[0131] The filter may contain additives such as a charcoal matrix. The matrix may be embedded in the nonwoven material. The charcoal may be added as particles or beads. The filter paper may be sprayed with a binder to impregnate the nonwoven matrix with charcoal. The matrix obtained after spraying the filter paper is an impregnated charcoal matrix. By this method, the charcoal in the impregnated charcoal nonwoven may be conventional activated carbon.

[0132] The filter assembly may be formed of more than one filter of the present invention. For example, several sections of the filter are arranged sequentially. The sections may have the same composition or different compositions. For example, the first section may contain an encapsulated flavorant, and the second section may contain an additive (such as a charcoal matrix) or no additive. The filter sections may be adjacent to each other (i.e., contiguous) or may be separated by a cavity formed by a paper tube and / or a paper wrapper. The cavity may accommodate the encapsulated flavorant as described above.

[0133] The filter of the present invention may be located at the upstream end of an aerosol-generating article or a smoking article, for example, as described in EP3861868 A1.

[0134] The filter may be used in cigarettes, electronic cigarettes, vaping devices, or other known smoking / aerosol-generating articles known in the art. The filter may be used in a combustion system (wherein an aerosol-generating substance is burned), or in a heat-not-burn system (wherein the aerosol-generating substance is heated such that an aerosol is generated from the substance without burning the substance). The aerosol-generating substance may be any substance containing tobacco, nicotine, flavorants, 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 matrix comprising natural fibers and a binder, wherein the natural fibers comprise 85% to 95% by weight, preferably 86.9% to 95% by weight, of the nonwoven matrix, and the binder comprises 5% to 15% by weight, preferably 5% to 13.1% by weight, of the nonwoven matrix, wherein, the nonwoven matrix 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 matrix has 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.

2. The filter according to the previous claim, wherein The natural fibers comprise 90% to 93% by weight of the nonwoven matrix, and / or the binder comprises 7% to 10% by weight of the nonwoven matrix.

3. The filter according to any one of the preceding claims, wherein, The nonwoven substrate has a bulk density of at least 50 mg / cm 3 , preferably at least 55 mg / cm 3 and most preferably at least 60 mg / cm 3 , and / or at most 110 mg / cm 3 , preferably at most 100 mg / cm 3 and most preferably at most 90 mg / cm 3 of bulk density.

4. The filter according to any one of the preceding claims, wherein, The nonwoven substrate has a basis weight of 40 to 65 g / m 2 , preferably 45 to 60 g / m 2 and most preferably 46 to 58 g / m 2 of basis weight.

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, which is preferably obtained by the kraft pulp process.

7. The filter according to the previous claim, wherein, The wood pulp comprises softwood pulp and / or hardwood pulp, preferably southern bleached softwood kraft SBSK and / or 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, which is an aqueous polymer emulsion, preferably soluble 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 polyvinyl acetate PVAc binders.

10. The filter according to the preceding claim, wherein, The binder comprises a combination of EVA and PVAc binders, wherein the ratio of EVA to PVAc binder 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 binder is a polyvinyl acetate stabilized with polyvinyl alcohol, preferably stabilized by a vinyl alcohol polymer, PVOH, dextrin or a combination thereof, wherein the EVA is stabilized with one or more of a surfactant, an emulsifier, a cellulose derivative, PVOH, a colloid and a combination thereof.

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

13. The filter according to any one of the preceding claims, wherein, The filter has a density of 100 to 200 mg / cm 3 , and / or wherein, The pressure drop across 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 ISO6565:2015.

14. The filter according to any one of the preceding claims, wherein, The nonwoven matrix is made in a rod form and wrapped with a wrapper 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, These natural fibres account for at least 86% by weight, preferably at least 87% by weight, more preferably at least 88% by weight and most preferably at least 89% by weight of the non-woven substrate, and / or at most 95% by weight, preferably at most 94% by weight and most preferably at most 93% by weight of the non-woven substrate, and / or the binder accounts for at most 14% by weight, preferably at most 13% by weight, more preferably at most 12% by weight and most preferably at most 11% by weight of the non-woven substrate, and / or at least 5% by weight, preferably at least 6% by weight and most preferably at least 7% by weight of the non-woven substrate.

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

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

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