Filters for aerosol-generating articles

Abstract

The present invention relates to a filter for use in a smoking article or an aerosol-generating article, and to an aerosol-generating article including a filter. The filter comprises a nonwoven fabric substrate containing natural fibers and a binder, wherein the natural fibers account for 85 to 95% by weight, preferably 86.9 to 95% by weight, of the nonwoven fabric substrate, and the binder accounts for 5 to 15% by weight, preferably 5 to 13.1% by weight, of the nonwoven fabric substrate. The nonwoven fabric 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. The nonwoven fabric 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 article or an aerosol-generating article comprising a nonwoven substrate that includes natural fibers and a binder, and to an aerosol-generating article that includes a filter. [Background technology]

[0002] For the past few years, smoking articles such as cigarettes have been equipped with acetate filters to filter harmful substances from the aerosol inhaled by the user. However, when discarded, used cigarettes, especially filters, often end up in the environment, potentially causing environmental harm. Due to increasing environmental awareness among consumers, manufacturers are increasingly seeking to replace commonly used non-biodegradable filters with biodegradable filters containing natural materials.

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

[0004] WO 2022 / 053621 relates to a filter comprising a low-density nonwoven substrate, the nonwoven substrate comprising natural fibers and a binder, which can be used as a filter for a smoking or vaping article.

[0005] Although the prior art discloses filters containing natural nonwoven materials, due to the low density of the filters, the nonwoven substrate may break during filter production, especially during / after the crimping process typically used for sheet substrate filter production, and there is a risk of the filter collapsing, which may result in an unpleasant smoking experience for the user. Moreover, during the production of the nonwoven substrate, binders tend to leak from the nonwoven substrate and contaminate the production machinery, thereby reducing the yield of filter production.

[0006] It is therefore desirable to provide a filter that can be manufactured with reduced risk of breakage during manufacturing and reduced risk of collapse during use and binder leakage during manufacturing of the nonwoven substrate. It is desirable to provide a method of manufacturing a filter. Summary of the Invention [Means for solving the problem]

[0007] The present invention provides a filter having a nonwoven substrate comprising natural fibers and a binder that solves some or all of the above problems.

[0008] A first embodiment of the present invention is directed to a filter for use in a smoking article or an aerosol-generating article, the filter comprising a nonwoven fabric substrate containing natural fibers and a binder, wherein the natural fibers account for 85 to 95% by weight, preferably 86.9 to 95% by weight, of the nonwoven fabric substrate, the binder accounts for 5 to 15% by weight, preferably 5 to 13.1% by weight, of the nonwoven fabric substrate, the nonwoven fabric 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 fabric 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. Preferably, the natural fibers account for more than 85% to 90% by weight of the nonwoven fabric substrate, and the binder accounts for 5 to less than 15% by weight of the nonwoven fabric substrate.

[0009] Filters made from nonwoven substrates with a tensile strength of less than 10 N / 5 cm have a high risk of substrate breakage or disintegration during manufacturing due to the low tensile strength. The above composition results in a filter made from durable natural materials that have inhalation and nicotine retention properties similar to those familiar to consumers from filters known in the art. Furthermore, binder leakage from the nonwoven substrate during manufacturing is reduced.

[0010] According to the second embodiment, in the preceding embodiment, the natural fibers comprise 90-93% by weight of the nonwoven substrate, and / or the binder comprises 7-10% by weight of the nonwoven substrate.

[0011] Preferably, the natural fibers account for 91 to 95% by weight of the nonwoven fabric substrate, and / or the binder accounts for 5 to 9% by weight. More preferably, the natural fibers account for 93 to 95% by weight of the nonwoven fabric substrate, and / or the binder accounts for 5 to 7% by weight. A reduction in the amount of binder leads to improved biodegradability.

[0012] Further, in any of the preceding embodiments, the natural fibers comprise 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 comprises 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.

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

[0014] According to a fourth embodiment, in any one of the preceding embodiments, the nonwoven fabric substrate has a density of 40 to 65 g / m 2 , preferably 45 to 60 g / m 2 , and most preferably 46 to 58 g / m 2 It has an areal density of

[0015] In the above embodiment, the risk of leakage from the binder can be further reduced.

[0016] According to a fifth 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, 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, most preferably at least 2.5 mm.

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

[0018] According to a seventh embodiment, in the preceding embodiments, the wood pulp comprises softwood pulp and / or hardwood pulp, preferably Southern Bleached Softwood Kraft (SBSK) and / or Northern Bleached Softwood Kraft (NBSK), and 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 no more than 25% NBSK, more preferably no more than 5% NBSK.

[0019] The use of natural fibers reduces the adverse impact of the filter on the environment. Moreover, nonwoven substrates made from wood pulp provide similar filter capacity (pressure drop and nicotine retention characteristics) as filters known in the art. As a result, the adverse impact of the filter on the environment can be reduced while maintaining similar filter capacity. Moreover, a high percentage of SBSK tends to reduce the pressure drop of the filter compared to a high percentage of NBSK. Therefore, the ratio of SBSK to NBSK can be used to adjust the pressure drop of the filter.

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

[0021] According to a ninth 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.

[0022] According to the tenth embodiment, in the preceding embodiments, the binder comprises a combination of EVA and PVAc adhesive, and the ratio of EVA to PVAc adhesive is preferably 70:30 to 30:70, more preferably 60:40 to 40:60, even more preferably 55:45 to 45:55, and most preferably 50:50.

[0023] According to an eleventh embodiment, in the ninth or tenth embodiment, the PVAc adhesive is a polyvinyl alcohol stabilized polyvinyl acetate, preferably stabilized by a vinyl alcohol polymer, PVOH, dextrin, or a combination thereof, and 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 binders mentioned above, and water-soluble binders in general, increase the rate at which the filter degrades in the environment: upon exposure to rain or soil, the water-soluble binder dissolves and the filter breaks down more easily, thereby accelerating the natural aging of the filter.

[0025] According to the twelfth embodiment, in any one of the preceding embodiments, the nonwoven substrate comprises a flavor additive.

[0026] The addition of flavoring agents to the filter enhances the consumer experience, particularly as the flavoring agent can mask the flavor of the natural fiber material contained in the filter.

[0027] According to the thirteenth embodiment, in any one of the preceding embodiments, the reel width of the nonwoven fabric substrate is 50 to 240 mm, preferably 100 to 220 mm, for example 120 to 180 mm.

[0028] The reel width may depend on the circumference of the filter. The smaller the circumference, the narrower the width. More specifically, if the filter circumference is about 16.8 mm ("Super Slim" configuration), the reel width is preferably 50-100 mm. If the filter circumference is about 21.5 mm ("Slim" configuration), the reel width is preferably 100-160 mm. If the filter circumference is about 24.2 mm ("King Size" configuration), the reel width is preferably 120-180 mm.

[0029] According to a fourteenth embodiment, in any one of the preceding embodiments, the nonwoven fabric substrate is crimped in the machine direction to 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] A crimp depth within the above range provides the desired crimp effect while reducing the risk of undesirable cracking in the nonwoven substrate.

[0031] According to a fifteenth embodiment, in any one of the preceding embodiments, the filter has a density of 100 to 220 mg / cm 3 or 100-200 mg / cm 3 , e.g., 140 mg / cm 3 and / or the pressure drop in the filter is 1.3 to 5.0 mmWC / mm or 1.3 to 4.5 mmWC / mm, preferably 1.8 to 3 mmWC / mm, preferably determined according to the conditions set out in ISO 6565:2015.

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

[0033] Pressure drops within the above ranges are similar to those of conventional cellulose acetate filters, and therefore users consuming smoking articles / aerosol-generating devices using the described filters will have a desirable consumption experience.

[0034] According to a 17th embodiment, in any one of the preceding embodiments, the nonwoven fabric substrate is delivered in a rod form and wrapped in a wrapper paper having a thickness of 24 to 120 gsm or 25 to 50 gsm, preferably 27 to 45 gsm and / or 0.03 to 0.13 mm or 0.03 to 0.06 mm, preferably 0.043 to 0.125 mm.

[0035] For example, the circumference may be 16 to 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.

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

[0037] The above ranges are commonly used in modern smoking articles / aerosol generating devices, and therefore filters within the above ranges can be used in a variety of applications.

[0038] A nineteenth embodiment relates to an aerosol-generating article, preferably a cigarette or a heat-and-burn aerosol-generating article, comprising a filter according to any one of the preceding embodiments.

[0039] A twentieth embodiment is directed to a method of manufacturing a nonwoven substrate for use in a smoking article or an aerosol-generating article, preferably including a filter according to any one of the first to eighteenth embodiments, the method comprising the steps of providing the nonwoven substrate arranged as a continuous sheet (also referred to herein as a "laminate") on a bale or pallet, inserting the nonwoven substrate into a manufacturing facility for production of the filter, and crimping the nonwoven substrate into a filter.

[0040] Preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a plot showing tensile strength measurements of exemplary nonwoven substrates at various thicknesses and binder contents. [Figure 2] 1 is another plot showing tensile strength measurements of exemplary nonwoven substrates at various thicknesses and binder contents. [Figure 3] 1 is a plot of stiffness versus pressure drop for an exemplary filter including a nonwoven substrate. [Figure 4a] 1 shows the arrangement of a nonwoven material according to a first embodiment. [Figure 4b] 10 shows the arrangement of a nonwoven material according to a second embodiment. [Figure 5] The space requirements for a nonwoven substrate supplied by bobbins are shown as well as the space requirements for a nonwoven substrate stored on bales / pallets by a lamination process, i.e., by a known rolling process. DETAILED DESCRIPTION OF THE INVENTION

[0042] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0043] Filters comprising nonwoven substrates for use in smoking articles or aerosol-generating articles are described in more detail below.

[0044] Nonwoven substrates refer to substrates made from fibrous materials in which the fibers are bonded to one another mechanically, chemically, or by a binder, and are well known in the art.

[0045] A filter according to an embodiment includes a nonwoven fabric substrate including natural fibers and a binder. Preferably, the nonwoven fabric substrate is prepared as a sheet. In the nonwoven fabric substrate, the natural fibers account for 85% to 95% by weight of the nonwoven fabric substrate, and the binder accounts for 5 to 15% by weight of the nonwoven fabric substrate. Preferably, the natural fibers account for more than 85% to 90% by weight of the nonwoven fabric substrate, and the binder accounts for 5 to less than 15% by weight of the nonwoven fabric substrate.

[0046] To avoid breakage of the nonwoven substrate and / or collapse of the filter containing the nonwoven substrate during filter manufacture, a nonwoven substrate is used 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. Filters containing such nonwoven substrates have been found to be particularly resistant to collapse, and these filters have been produced with high yields. The thickness of the nonwoven substrate is 25 cm according to EN ISO 9073-2:1996 "Test Methods for nonwovens." 2 The thickness is measured using a thickness measuring device that applies a pressure of 0.5 kPa to the test specimen with a pressing area of ​​100 mm.

[0047] In some embodiments, the natural fibers comprise 90-93% by weight of the nonwoven fabric substrate and / or the binder comprises 7-10% by weight of the nonwoven fabric substrate. More preferably, the natural fibers comprise greater than 90% to 93% by weight of the nonwoven fabric substrate and the binder comprises 7% to less than 10% by weight of the nonwoven fabric substrate.

[0048] In some embodiments, the nonwoven substrate has a sheet density of at least 50 mg / cm, also referred to as sheet density. 3 , preferably at least 55 mg / cm 3 , most preferably at least 60 mg / cm 3 and / or a bulk density of up to 140 mg / cm 3 , preferably up to 130 mg / cm 3 , more preferably at most 120 mg / cm 3 , most preferably up to 110 mg / cm 3 , preferably up to 100 mg / cm 3 , most preferably up to 90 mg / cm 3 It has a volume density of

[0049] The volume density of a nonwoven substrate can be obtained by dividing the areal density or basis weight of the substrate by the thickness of the substrate.

[0050] In some embodiments, the nonwoven material has a weight, also referred to as 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 It has an areal density of

[0051] The areal density of a sheet of nonwoven substrate is determined by placing the sheet on a balance and measuring its weight. The weight is then divided by the area of ​​the sample to obtain the areal density / basis weight. For example, standard ISO 536:2019 can be used to determine the areal density of nonwoven substrates.

[0052] The higher the areal / volume density of a nonwoven material for a given length, the higher the pressure drop of a filter made using that nonwoven material.

[0053] 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 fibers or sisal fibers, bast fibers such as jute fibers, hemp fibers, flax fibers, or kenaf fibers, and / or semi-natural fibers such as viscose fibers and / or lyocell fibers. While the natural fibers may be selected from any of the above, in some embodiments, it is desirable to select natural fibers that have particularly good biodegradability so as to enhance environmental compatibility.

[0054] For example, the natural fibers may comprise, or preferably consist of, wood fibers selected from softwood 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, the natural fibers are Southern Bleached Softwood Kraft (SBSK) and / or Northern Bleached Softwood Kraft (NBSK), and 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).

[0055] The average length of the natural fibers, according to some embodiments, is at most 3.5 mm, preferably at most 3.0 mm, 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, most preferably at least 2.5 mm.

[0056] An exemplary SBSK material suitable for the filter is Golden Isles processed fluff, grade 4623. This material has a fiber length of 2.68 mm and a weight of 765 g / m 2 and a basis weight of

[0057] The binder added to the natural fibers to form the nonwoven substrate may be an aqueous polymer emulsion, preferably containing at least one binding agent that is water-soluble. The binder may be selected from one or more of aqueous copolymer dispersions of ethylene vinyl acetate (EVA) and polyvinyl acetate (PVAc) adhesives, cellulose derivatives such as ethyl / methyl cellulose, hydroxyethyl / methyl cellulose and / or carboxymethyl cellulose, and / or polysaccharides (or polysaccharide derivatives) such as dextrin or starch.

[0058] 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 70:30 to 30:70, more preferably 60:40 to 40:60, and most preferably 55:45 to 45:55. In some embodiments, the ratio of EVA to PVAc adhesive is 50:50. One advantage of these binders is that they do not adversely affect phenolic delivery.

[0059] The PVAc adhesive may be PVAc stabilized with PVOH (vinyl alcohol polymer), dextrin, or a combination thereof, and more preferably, PVAc adhesive stabilized with PVOH. The advantages of PVAc adhesive are its high adhesive properties with natural fibers, fast binder cure, and its compatibility with EVA dispersions. An exemplary polyvinyl alcohol-stabilized polyvinyl acetate (PVAc) adhesive is Vinamul 8482, marketed by Celanese.

[0060] Exemplary copolymers of EVA are those stabilized with surfactants, emulsifiers, cellulose derivatives, PVOH, colloids, and combinations thereof. The copolymers are hydrophilic so that they can easily wet textile materials and have good adhesive properties. Preferred copolymers of EVA in aqueous copolymer dispersions with self-crosslinking properties are based on vinyl acetate and surfactant-stabilized ethylene. These copolymers impart a particularly neutral flavor and have a low volatile organic compound (VOC) content.

[0061] To produce a filter from a nonwoven fabric sheet, the nonwoven fabric sheet preferably has a reel width of 50 to 240 mm or 100 to 220 mm, preferably 70 to 170 or 120 to 180 mm.

[0062] Preferably, the nonwoven substrate is stored on one or more bales / pallets, preferably by a lamination process. In other words, the nonwoven material can be stored in a state arranged as a continuous sheet, also referred to herein as "lamination," to preferably form a bale. A continuous sheet of nonwoven material, or a bale formed by a continuous nonwoven material, can be arranged on a pallet or similar support. Note that the term "continuous sheet" is used herein to refer to both a single continuous sheet made in one piece and a sheet composed of spliced ​​portions of a nonwoven sheet. 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 the art can be spliced ​​together to form a continuous sheet on the nonwoven material. For example, two or more bobbins of material, such as 10 bobbins, can be "converted," i.e., arranged, into a continuous sheet stored on a bale / pallet.

[0063] Below, the process for feeding the nonwoven substrate from a bale / pallet to a filter manufacturing apparatus for manufacturing filters, as well as the layering process for storing the nonwoven substrate, i.e., storing the nonwoven substrate on a bale and / or pallet, are described in more detail.

[0064] According to a first embodiment, multiple individual layers of a continuous sheet of nonwoven substrate are placed on a pallet and / or bale. As noted above, a continuous sheet of nonwoven material, or a bale formed by a continuous nonwoven material, can be placed on a pallet or similar support.

[0065] One such example is shown in Figure 4a. Adjacent portions (401a, 401b, 401c) of the continuous nonwoven sheet are positioned adjacent to one another in a generally horizontal direction H, and the adjacent portions (401a, 401b, 401c) may partially overlap. The nonwoven substrate is positioned on the pallet or bale such that, upon removal of the nonwoven substrate from the pallet or bale, each individual first layer of the nonwoven substrate is removed from the pallet or bale before each individual second layer below the individual first layer of the nonwoven substrate is removed from the pallet or bale. Furthermore, the nonwoven substrate is positioned on the pallet or bale such that the portions (401a, 401b, 401c) of the nonwoven substrate forming each individual layer are removed from the pallet or bale in a generally horizontal direction H. Moreover, each individual layer of nonwoven material may extend across the entire area of ​​the pallet or bale. The nonwoven substrate arranged as described above is fed in the direction P for the production of the filter, preferably by a lamination step (which can be carried out in the same factory where the filter is produced or which can be carried out previously in a factory different from the one where the filter is produced). The lamination step for forming the bale is preferably carried out in the factory of the nonwoven process, for example of the nonwoven supplier, although it should be noted that it is not excluded that the lamination step for forming the bale can be carried out in the same factory where the filter is produced.

[0066] In a second embodiment, the nonwoven substrate is provided on a pallet and / or bale, with the individual stacks (420a, 420b) of nonwoven material positioned adjacent to one another. As discussed above, a continuous sheet of nonwoven material, or a bale formed by a continuous nonwoven material, can be positioned on a pallet or similar support. One such example is shown in FIG. 4b. In this example, adjacent portions (402a, 402b) of the continuous nonwoven sheet are positioned one above the other in a generally vertical direction V, and the adjacent portions may substantially completely overlap. While in the previous example, adjacent portions (402a, 402b) of the continuous nonwoven sheet were positioned adjacent to one another to form individual layers, in this example, adjacent portions (402a, 402b) of the continuous nonwoven sheet are positioned one above the other to form individual stacks (420a, 420b) of the nonwoven substrate. The nonwoven substrate is arranged on a pallet or bale such that, upon removal of the nonwoven substrate from the pallet or bale, the individual first laminates (420a) of the nonwoven substrate are removed before the individual second laminates (420b) adjacent to the individual first laminates (420a) of the nonwoven substrate are removed from the pallet or bale. Furthermore, the nonwoven substrate is arranged on the pallet or bale such that the portions (402a, 402b) of the nonwoven substrate forming the individual laminates (420a, 420b) are removed from the pallet or bale in a generally vertical direction V. Furthermore, each of the individual laminates (420a, 420b) of nonwoven material may extend across the entire height of the nonwoven substrate arranged on the pallet or bale. Preferably, by a lamination process, the nonwoven substrate arranged as described above is fed in a direction P for the production of a filter. It should be noted that the lamination process to form the veil is preferably carried out in the nonwoven processing plant of, for example, the nonwoven supplier, although it is not excluded that the lamination process to form the veil can be carried out in the same plant in which the filters are manufactured.

[0067] Using a lamination process to supply nonwoven substrates in the form of bales and / or stored on pallets has the advantage of reducing area requirements within a manufacturing facility compared to other commonly used arrangements, such as rolling processes, in which nonwoven sheets are placed on one or more bobbins.

[0068] Figure 5 illustrates the difference in space requirements between the rolling process [a] and the supply of nonwoven substrate stored on bales / pallets for lamination [b] to produce filters. Typically, in the rolling process [a], at least two large bobbins (501) are provided to supply the nonwoven substrate to the manufacturing facility. Typically, the nonwoven substrate is fed from the bobbins (501) into a buffer (502) before being transferred to the crimping unit (510). When the bobbin needs to be replaced, the bobbin's rotational motion must be stopped, and the buffer allows the nonwoven substrate to be spliced ​​from the currently used bobbin to a subsequent bobbin while allowing the filter manufacturing process to continue uninterrupted.

[0069] In contrast, if the nonwoven substrates are stored in bales / pallets by the lamination step [b], the nonwoven substrates delivered onto the bales or pallets (503) can be directly fed (pulled from the bales / pallets) to a filter manufacturing process, e.g., to the crimping unit (510) for filter production. Because the nonwoven substrates are delivered onto bales or pallets, buffers for splicing the substrates are at least reduced or, in some embodiments, not required during the lamination step. Indeed, it is possible to connect the nonwoven substrate from a currently used bale / pallet to the leading edge of the nonwoven substrate of a subsequent bale / pallet well before the trailing edge of the nonwoven substrate of the currently used bale / pallet is delivered to the crimping unit. In other words, the trailing edge of the nonwoven substrate is always available, making it easier to splice the nonwoven substrates of two bales / pallets, as opposed to a bobbin arrangement in which the nonwoven substrate rotates and moves on the nonwoven substrate or bobbin, which requires the rotational movement of the bobbin to be stopped.

[0070] This also leads to significantly less space requirements in the manufacturing facility when compared to the space required for rolling processes. In this regard, it should be noted that the lamination process makes it possible to store nonwoven substrates on bales having lengths that would normally be stored on about 10 bobbins in the known art.

[0071] Advantageously, the lamination process for storing the nonwoven substrate, e.g., in the form of a bale, allows a manufacturing facility to provide biodegradable filters comprising nonwoven material having a layout similar to that of conventional filters, e.g., cellulose acetate filters, while providing for smaller space requirements and more efficient changeover of subsequent supply bales / pallets that does not require (or at least reduces) the need for buffers required in known techniques to compensate for interruptions in bobbin rotation.

[0072] To improve the quality of the filter produced by the nonwoven fabric substrate, in an exemplary embodiment, the nonwoven fabric substrate is crimped before being formed into a filter. In this exemplary embodiment, to obtain straight crimp grooves, the nonwoven fabric substrate is crimped in the machine direction of a crimper to a crimp 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. The above ranges provided good filter properties without any breakage or cracking of the nonwoven fabric substrate.

[0073] Although the crimping process can improve the quality of the filter, in some embodiments, this additional step can be eliminated from the manufacturing process and the filter can be formed directly from the nonwoven substrate.

[0074] The crimped nonwoven substrate can then be rolled from the sheet into a typical cylindrical filter / rod shape by wrapping the sheet around the longitudinal axis of the filter. In other embodiments, the crimped nonwoven substrate is pressed into a typical cylindrical filter / rod shape. While cylindrical / rod filters are most common in the art, the crimped nonwoven substrate can also have a rectangular, conical, spherical, or any other shape that is compatible with the smoking article / aerosol-generating device in which the nonwoven substrate will be used.

[0075] Additionally, flavorings may be added to the filter to provide a more pleasant smoking experience for the user.

[0076] To be compatible with commonly used smoking articles / aerosol-generating devices, the filter's outer circumference (including the thickness of the filter wrapper) is preferably 16 to 28 mm or 20 to 28 mm, more preferably 22 to 26 mm, even more preferably 24 to 25 mm, and most preferably 24.2 mm. For example, the outer circumference may be 16 to 28 mm, e.g., 16.8 mm, or about 16 to 26 mm, e.g., 21.5 mm, or about 16.8 to 24.20 mm.

[0077] To allow for handling and storage of the filtration substrate, the rolled nonwoven substrate may be wrapped in a wrapper having a basis weight of 24-120 gsm, 25-50 gsm, or 27-100 gsm and / or a thickness of 0.03-0.125 mm or 0.03-0.06 mm. For example, a 0.100 mm, 0.110 mm, or 0.120 mm plug wrap may advantageously provide increased filter stiffness.

[0078] Preferably, the filter obtained using the above material has a density of 100 to 200 mg / cm 3 , preferably 120 to 160 mg / cm 3 , e.g., 150 mg / cm 3 The filter has a density of 1.3 to 4.5 mmWC / mm, preferably 1.8 to 3 mmWC / mm, and the pressure drop across the filter is preferably determined according to the conditions set forth in ISO 6565:2015. The filter density may vary depending on the filter circumference. For example, if the filter circumference is about 16.8 mm, the filter density may be 106 to 211 mg / cm. 3 and the pressure drop is between 2.78 and 4.44 mmWC / mm. When the filter is about 21.5 mm, the density of the filter is between 130 and 208 mg / cm. 3 and the pressure drop is between 2.04 and 3.70 mmWC / mm. When the filter is about 24.2 mm, the density of the filter is 123 to 184 mg / cm. 3 and the pressure loss is between 1.67 and 4.44 mmWC / mm.

[0079] Exemplary Nonwoven Substrates The following describes in detail examples of processing of nonwoven fabric substrates. Table 1 shows four samples (lots 2, 4, 7 and 8) of nonwoven fabric substrates manufactured taking into account the above properties.

[0080] Lots 2, 4, 7, and 8 were produced with fiber contents ranging from 86.9 to 91.8% and corresponding binder contents ranging from 8.2 to 13.1%. Of the four samples, Lot 4 had the lowest binder content of 8.2%, followed by Lot 7 with a binder content of 8.5%, then Lot 2 with a binder content of 9.5%, and Lot 8 with the highest binder content of 13.1%.

[0081] The areal density, thickness, and dry tensile strength of each sample were measured. To measure tensile strength, a 5 cm strip of nonwoven substrate was cut from each nonwoven substrate and secured in a tensile strength measuring device. For example, a Zwick Roell tensile strength measuring device may be used, and tensile strength is preferably measured under the test conditions defined in ISO 9073-3. However, other methods, such as the measurement method defined in ISO 9073-18:2007, are also possible. In this particular example, the measurement method defined in ISO 9073-3 was used. The tensile strength measuring device applied force to each end of the 5 cm strip until the strip reached its breaking point and broke / fractured. The required force and the elongation of the strip were then measured.

[0082] Table 1 below shows the measurements for density, thickness, and tensile strength for each sample (Lots 2, 4, 7, and 8). The density of the sheet was calculated by dividing the areal density by the thickness.

[0083] [Table 1]

[0084] As can be seen from Table 1, the surface density of the samples ranged from 44.4 to 81.63 mg / cm3 The nonwoven substrate of Lot 7 was 46.99 g / m 2 Lot 1 had the lowest areal density of 50.61 g / m, followed by Lot 2 with an areal density of 55.58 g / m 2 Lot 8 having an areal density of 55.58 g / m 2 followed by Lot 2 which has the highest areal density of 1000.

[0085] The thickness of each of the samples ranged from 0.62 to 1.19 mm. Of the four samples, Lot 4 had the thinnest thickness at 0.62 mm, followed by Lot 7 with a thickness of 0.78 mm, then Lot 2 with a thickness of 0.92 mm, and Lot 8 with a thickness of 1.19 mm.

[0086] The tensile strength measured for the samples ranges from 14.2 to 28.2. From the four samples, Lot 7 has the lowest tensile strength of 14.2 N / 5 cm, followed by Lot 8 with a tensile strength of 14.7 N / 5 cm, then 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.

[0087] The above shows that, in general, a high volume / sheet density of a nonwoven 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 in Table 1, where Lots 2 and 7 have similar volume densities but significantly different tensile strengths.

[0088] To demonstrate the effect of certain parameters on tensile strength, second and third batches of samples were prepared. Figures 1 and 2 show the tensile strength of each sample from the second and third batches of nonwoven substrates, relative to the thickness and binder content of each sample. In Figure 1, substrates in regions 1 and 4 exhibit tensile strength sufficient for filter fabrication, substrates in region 2 exhibit tensile strength that is somewhat sufficient for filter fabrication, and substrates in region 3 exhibit tensile strength that is not sufficient for filter fabrication due to a high risk of breakage. Similarly, in Figure 2, region 1 represents substrates with sufficient tensile strength, region 2 represents substrates with somewhat sufficient tensile strength, and region 3 represents substrates that do not have sufficient tensile strength for filter fabrication.

[0089] As can be seen particularly from Figure 1, when areal density and binder content are constant, tensile strength decreases as thickness decreases, thereby confirming the findings shown in Table 1, where we observed that tensile strength increases as volume density increases. Furthermore, when thickness, and therefore sheet / volume density, is held constant, tensile strength increases with binder content. Thus, the areal density, thickness, and binder content of a nonwoven all directly affect the resulting tensile strength.

[0090] Returning to the samples in Table 1, each of the sheets of nonwoven substrate from each of Lots 2, 4, 7, and 8 exhibited sufficient tensile strength to manufacture filters, but the production of Lots 7 and 8 was less productive than Lots 2 and 4. This was because a large amount of binder leaked from the substrate during production, contaminating the machinery used to manufacture the nonwoven sheets. This, in turn, led to reduced productivity because additional cleaning steps were required for the operations manufacturing Lots 7 and 8.

[0091] The amount of binder leakage from a nonwoven substrate depends on the binder content, material thickness, areal density, and ultimately sheet / volume density. For example, a low volume density, which provides little protection from binder leakage from the nonwoven material, increases the amount of binder leakage from the device. Similarly, increasing the binder content while holding other parameters constant also increases the amount of binder leakage from the nonwoven substrate. Additionally, for a given binder content and volume density, the impact of leakage increases with decreasing thickness because less textile material is provided to prevent binder leakage.

[0092] Therefore, while parameters affecting tensile strength suggest that a high binder content is desirable, leakage also increases with higher binder content, which should be prevented. Furthermore, if the thickness is too thin, high pressure is required during manufacturing, resulting in an uneven web of nonwoven material. Therefore, nonwoven substrates with relatively low thicknesses (high sheet / volume densities), such as in the range of 0.5-0.7 mm, and / or relatively low binder contents, such as in the range of 10%-7%, are most preferred.

[0093] Filter Characteristics As described above, filters were formed from the nonwoven sample material by crimping a sheet of nonwoven material, rolling the crimped sheet into a rod shape, and wrapping the rod-shaped nonwoven sheet in wrapping paper.

[0094] The resulting filters were then subjected to pressure drop and hardness / hardness measurements to determine whether the filters obtained according to the above method exhibited similar filtration characteristics as filters known in the art.

[0095] The hardness / stiffness module (SODIM-H) and pressure drop module (SODIM-PDVM) of the Sodiline measuring device were used to measure the filter hardness / stiffness and pressure drop. In the pressure drop module, a critical flow orifice and a vacuum generator were installed within a laminar flow system. The vacuum generator was activated and the pressure drop (in mmWC) across the filter was measured. In the hardness module, a movable jaw applied pressure to the side of the filter (in the axial direction of the cylindrical filter) and the amount of compression (deformation in tenths of a mm) was recorded.

[0096] FIG. 3 shows the test results for each of the filters manufactured. The measured pressure drop of the filters is plotted against their respective measured hardness. The filters were subjected to a pressure of 350 g force for 5 seconds in SODIM-H. It can be seen that as the filter hardness increases, the pressure drop across the filter decreases. Most preferred is a pressure drop in the range of 1.3 to 5 mm WC / mm or 1.3 to 4.5 mm WC / mm, preferably 1.8 mm WC / mm to 4.5 mm WC / mm or 1.8 to 3 mm WC / mm. Therefore, the hardness of each filter is preferably in the range of 2.5 mm to 1.3 mm, more preferably 2.3 mm to 1.5 mm. These hardness ranges are achieved when the filters are prepared as described above.

[0097] Therefore, the filter obtained from the above-mentioned nonwoven material provides a comfortable inhalation experience to the user. Furthermore, due to the high tensile strength of the material, the nonwoven sheet is prevented from breaking. Moreover, the natural nonwoven fibers and preferably the water-soluble binder provide a more environmentally friendly filter.

[0098] Filter Density The following table provides examples of the properties of the nonwoven filters of the present invention (particularly the volume density calculated for different circumferences and different sheet widths).

[0099] 1. Super Slim Nonwoven Filter: a) Example 1:

[0100] [Table 2]

[0101] b) Example 2:

[0102] [Table 3]

[0103] 2. Slim nonwoven fabric filter: a) Example 1:

[0104] [Table 4]

[0105] b) Example 2:

[0106] [Table 5]

[0107] 3. King Size Nonwoven Filter:

[0108] [Table 6]

[0109] Filter pressure loss The following table provides examples of pressure drop for nonwoven filters of the present invention as a function of different circumferences (i.e., filter configurations).

[0110] 1. Super Slim Filter:

[0111] [Table 7]

[0112] 2. Slim Filter:

[0113] [Table 8]

[0114] 3. King Size Filter:

[0115] [Table 9]

[0116] The filter of the present invention may include a capsule containing a flavoring agent, such as menthol. The encapsulated flavoring agent may have a core containing a liquid, powder, or gel encapsulated by a shell, sheet, or coating that forms a barrier material. The encapsulated flavoring agent may be a capsule that can be ruptured to release the flavoring agent before or during use. The barrier material may be frangible or breakable. The capsule can be crushed or otherwise broken or destroyed by a user to release the encapsulated flavoring agent. Typically, the capsule is broken just before smoking or heating is initiated. The term "fragile capsule" refers to a capsule whose shell can be broken by pressure, more specifically, whose shell can be ruptured under pressure applied by a user's finger (or any other pressure-generating means) when the user attempts to release the capsule's core.

[0117] The filter may include an additive such as a charcoal substrate. The substrate may be embedded in a nonwoven material. The charcoal may be added as particles or beads. To impregnate the nonwoven substrate with the charcoal, the charcoal may be sprayed onto the filter paper along with a binder. The resulting substrate after spraying onto the filter paper is the impregnated charcoal substrate. For this method, the charcoal in the impregnated charcoal nonwoven may typically be activated carbon.

[0118] A filter assembly may be formed from two or more filters of the present invention. For example, several filter segments are arranged one after the other. The segments may have the same or different compositions. For example, a first segment may contain an encapsulated flavoring agent, and a second segment may or may not contain an additive (e.g., a charcoal substrate). The filter segments may be adjacent to each other (i.e., abutting) or may be separated by a cavity formed by a paper tube and / or paper wrapper. The cavity may house an encapsulated flavoring agent, as described above.

[0119] A filter of the present invention may be positioned at the upstream end of an aerosol-generating article or smoking article, for example as described in EP 3861868 A1.

[0120] The filters may be used in cigarettes, e-cigarettes, vaporization devices, or other known smoking / aerosol-generating articles known in the art. The filters may be used in combustion systems, in which the aerosol-generating material is burned, or in heated non-combustion systems, in which the aerosol-generating material is heated to generate an aerosol from the material without burning the material. The aerosol-generating material may be any material containing tobacco, nicotine, flavoring agents, and / or other substances capable of providing an inhalable aerosol to the user.

Claims

1. A filter for use in a smoking article or an aerosol-generating article, the filter comprising a nonwoven fabric substrate comprising natural fibers and a binder, the natural fibers comprising 85% to 95% by weight, preferably 86.9 to 95% by weight, of the nonwoven fabric substrate, and the binder comprising 5 to 15% by weight, preferably 5 to 13.1% by weight, of the nonwoven fabric substrate; 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; A filter wherein 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.

2. The filter of claim 1 , wherein the natural fibers comprise 90 to 93% by weight of the nonwoven substrate, and / or the binder comprises 7 to 10% by weight of the nonwoven substrate.

3. The nonwoven substrate has a density of at least 50 mg / cm ３ , preferably at least 55 mg / cm ３ , most preferably at least 60 mg / cm ３ and / or a bulk density of at most 110 mg / cm ３ , preferably at most 100 mg / cm ３ , most preferably at most 90 mg / cm ３ 3. The filter of claim 1, having a volume density of

4. The nonwoven fabric substrate has a density of 40 to 65 g / m ２ , preferably 45 to 60 g / m ２ , most preferably 46 to 58 g / m ２ 4. The filter of claim 1, having an areal density of

5. 5. The filter according to any one of claims 1 to 4, wherein the natural fibres have an average length of at most 3.5 mm, preferably at most 3.0 mm, most preferably at most 2.8 mm, and / or the average length of the natural fibres is at least 2.0 mm, preferably at least 2.3 mm, most preferably at least 2.5 mm.

6. A filter according to any one of claims 1 to 5, wherein the natural fibres comprise or preferably consist of wood pulp, said wood pulp preferably being obtained by the Kraft process.

7. 7. The filter of claim 6, wherein the wood pulp comprises softwood pulp and / or hardwood pulp, preferably Southern Bleached Softwood Kraft (SBSK) and / or Northern Bleached Softwood Kraft (NBSK), 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 no more than 25% NBSK, more preferably no more than 5% NBSK.

8. A filter according to any one of the preceding claims, wherein the binder is a water-based polymer emulsion and comprises at least one binding agent which is preferably water-soluble.

9. A filter according to any preceding claim, wherein the binder comprises one or more of an aqueous copolymer dispersion of ethylene vinyl acetate (EVA) and a polyvinyl acetate (PVAc) adhesive.

10. 10. The filter of claim 9, wherein the binder comprises a combination of EVA and PVAc adhesive, the ratio of EVA to PVAc adhesive being 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. 11. The filter of claim 9 or 10, wherein the PVAc adhesive is polyvinyl alcohol stabilized polyvinyl acetate, preferably stabilized by vinyl alcohol polymer, PVOH, dextrin, or a combination thereof, and the EVA is stabilized by one or more of a surfactant, an emulsifier, a cellulose derivative, PVOH, a colloid, and a combination thereof.

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

13. The filter has a density of 100 to 200 mg / cm ３ and / or 13. The filter according to any one of claims 1 to 12, 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 set out in ISO 6565:2015.

14. 14. The filter of any one of claims 1 to 13, wherein the nonwoven substrate is delivered in rod form and wrapped in a wrapper having a basis weight of 25 to 50 gsm and / or a thickness of 0.03 to 0.06 mm.

15. the natural fibers comprise 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 comprises 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; A filter according to any one of claims 1 to 14.

16. An aerosol-generating article, preferably a cigarette or a heat-and-burn aerosol-generating article, comprising a filter according to any one of claims 1 to 15.

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

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