Sustainable filter and method of manufacture thereof

Abstract

A method of manufacturing a sustainable filter material for use in smoking articles, aerosol generating articles and the like, the method comprising the steps of: a) Providing a longitudinally advancing flow of an airlaid material; b) Subjecting the longitudinally advancing airlaid material to a superheated gas; and c) Drying the longitudinally advancing airlaid material (e.g., subsequent to subjecting the airlaid material to the superheated gas) by exposure to hot gas.

Description

[0001] Sustainable filter and method of manufacture thereof

[0002] INTRODUCTION

[0003] The present invention provides a sustainable filter material for use in smoking articles, such as a cigarette, tobacco heating product, or a heat-not-burn product, together with a method of manufacture thereof.

[0004] BACKGROUND

[0005] Filter materials for use in smoking articles, such as, cigarettes, tobacco heating products, or heat-not-burn (HNB) products, may be manufactured from a number of different materials. According to Euromonitor International, 98% of commercial cigarette filters comprise at least some cellulose acetate. However, cellulose acetate is not biodegradable and, as a result, cigarette filter material (and cigarette butts) comprising cellulose acetate may persist in the environment for many years. Therefore, there is a need for filter materials (such as paper) that do not comprise single-use plastics and are readily biodegradable.

[0006] Alternative filtration materials to cellulose acetate include airlaid non-woven papers. Filters comprising airlaid paper as the filtering material are well known in the art. Airlaid paper filters offer a number of advantages over cellulose acetate filters in terms of enhanced biodegradability and higher filtration efficiencies at a given pressure drop. However, they also have a number of disadvantages compared to cellulose acetate filters. Due to the manufacturing process of the airlaid paper material, the material itself has a high variance in terms of weight and thickness. When being converted into filters, this high variance leads to significant inconsistencies in pressure drop variations across the filter, reduced absorption of the user’s saliva leading to poor taste quality, and an unattractive pre and post-smoking appearance (as a result of staining). Thus the experience of smoking cigarettes with conventional airlaid paper filters is not comparable to that from a conventional cellulose acetate filtered cigarette.

[0007] It is therefore desirable to provide a new filter material (e.g., modified airlaid material) for use in a smoking article (e.g., a cigarette, a tobacco heating product, a heat-not-burn (HNB) product) which provides acceptable filtration properties (e.g., pressure variation, aerosol temperature) whilst improving on the known filter materials by providing better customer experience (e.g., taste, absorption) and being more readily biodegradable (e.g., from a combination of increased absorption and reduced tensile strength).

[0008] SUMMARY OF THE INVENTION

[0009] According to the present invention in a first aspect there is provided a method of manufacturing a sustainable filter material for use in smoking articles, aerosol generating articles, and the like, the method comprising the steps of a) providing a longitudinally advancing flow of an airlaid material; b) subjecting the longitudinally advancing airlaid material to a superheated gas (e.g., steam); and c) drying the longitudinally advancing airlaid material (e.g., subsequent to subjecting the airlaid material to the superheated gas). The longitudinally advancing airlaid material may be dried by exposure to hot gas (e.g., hot air).

[0010] The applicants have surprisingly found that by subjecting a longitudinally advancing flow of airlaid paper material to a superheated gas (e.g., steam), the bonds holding the fibers of the airlaid paper material together become weaker. This enables the airlaid paper material to be stretched; the overall strength of the airlaid paper material becomes weaker and more susceptible to breaking down and or tearing.

[0011] Without wanting to be bound by theory, it is thought that the absorption of the vapors of the superheated gas (e.g., steam) into the airlaid paper material degrades the strong hydrogen bonds which hold the fibers of the airlaid paper material together. It is further thought that the longer the airlaid paper material is exposed to the superheated gas, the further these bonds will degrade.

[0012] The applicants have further surprisingly found that drying the airlaid paper material by exposure to hot gas (e.g. hot air), subsequent to being subjected to a superheated gas (e.g., steam), partially strengthened the airlaid paper material and resulted in significantly different properties. This dual process of absorption and then drying weakens the overall product whilst maintaining enough strength for it to function as intended. This weakened product is therefore more susceptible to breaking down which means it is more readily biodegradable than the original airlaid material whilst maintaining the expected functional performance.

[0013] Without wanting to be bound by theory, it is thought that drying the airlaid material partially reforms the bonds between the fibers of the airlaid paper material. However, because the airlaid paper material has been stretched in the previous step due to a degradation of the bonds between the fibers, the end result is a significantly different arrangement of fibers to the original airlaid paper material which leads to significantly different material properties.

[0014] The method may further comprise the step of embossing the longitudinally advancing airlaid material (e.g., after the drying step). The applicants found that embossing the airlaid filter material resulted in a reduced variation of pressure drop across the filter when compared to embossing airlaid filter material which had not been subjected to the previous method steps.

[0015] The method may further comprise gathering laterally the longitudinally advancing airlaid material into rod form. This enables the rods to be cut into appropriate sizes to form filter segments.

[0016] The sustainable filter material (produced by the method of this aspect of the invention) may have an absorption of 4.20 mg / mg or above, for example from 4.30 mg / mg to 4.60 mg / mg, for example 4.49 mg / mg. Preferably the sustainable filter material has an absorption from 4.45 mg / mg to 4.55 mg / mg. The applicants found that the partial degradation of the airlaid material due to the method steps resulted in a sustainable filter material with higher absorption when compared to a filter made of airlaid filter material which had not been subjected to the heating and drying method steps. The absorption was measured using a capillary test which is commonly used in the field. The applicants surprisingly found that the higher absorption provided by the sustainable filter material produced by the method of this aspect of the invention provided better taste quality because the user’s saliva was less present on the mouth section of the filter material.

[0017] The sustainable filter material may have a density of 0.210 mg / mm3or less, for example from 0.200 mg / mm3to 0.210 mg / mm3, for example 0.206 mg / mm3. Preferably, the sustainable filter material has a density from 0.203 mg / mm3to 0.209 mg / mm3. The applicants found that the sustainable filter material produced by the method of this aspect of the invention had a lower density than a filter made from the original airlaid material. This is because the fibers of the airlaid material have been stretched apart resulting in a reduced mass per given area of the airlaid material.

[0018] The sustainable filter material may have a tensile strength of 1 .2 N or less, for example from 0.5 N to 1 .2 N, for example 0.8 N. Preferably, the sustainable filter material has a tensile strength from 0.6 N to 1.0 N. The applicants found that due to the degraded bonds and subsequently more separated material fibers, the tensile strength of the sustainable filter material was reduced compared to the original airlaid material. The applicants found that the sustainable filter material produced by the method of this aspect of the invention is easier to emboss during the embossing process and therefore provides a reduced variation of pressure drop across a filter made from this sustainable filter material. Furthermore, the applicants found that the sustainable filter material was more susceptible to decomposition due to the reduced tensile strength combined with the higher absorption thus making the filter material more sustainable and environmentally friendly.

[0019] The sustainable filter material may be paper (e.g., cellulose pulp). The paper may be, for example, filter paper, non-woven paper, airlaid paper or cellulose / lyocell / viscose based paper. The paper may be a non-woven paper made with non-plastic plant based fibres (e.g., flax, hemp, jute, sisal, abaca, coconut, bamboo, starch or wood pulp) or a blend of these materials. Preferably, the sustainable filtering material does not comprise cellulose acetate.

[0020] The sustainable filter material may have a basis weight from 30 GSM to 200 GSM, for example from 45 GSM to 120 GSM, for example 62 GSM. Preferably, the sustainable filter material has a basis weight from 50 GSM to 70 GSM.

[0021] The sustainable filter material, which may be paper, may have a thickness from 100 pm to 2000 pm, for example from 300 pm to 800 pm, for example 400pm. Preferably, the paper has a thickness from 300 pm to 500 pm.

[0022] The superheated gas used in the method of the invention may be steam.

[0023] The pressure of the steam may be from 0.5 bar to 1 .2 bar, for example from 0.6 bar to 1 bar, for example 0.8 bar. Preferably, the steam has a pressure from 0.70 bar to 0.90 bar.

[0024] The saturation of steam may be from 100°C to 150°C, for example 1 10°C to 140°C, for example 120°C to 130°C. Preferably, the saturation of steam is 125°C.

[0025] The steam may be made from distilled water. The applicants found that using distilled water to form the superheated steam ensured that the steam did not carry impurities which may have been absorbed by the filter material.

[0026] The hot gas used to dry the airlaid material in the method of the invention may be air. The air used to dry the filter material may be from 140°C to 350°C, for example from 200°C to 300°C, for example 240°C. Preferably, the temperature of air is from 210°C to 270°C.

[0027] According to the present invention in a second aspect there is provided a filter for use in smoking articles, aerosol generating articles, and the like, comprising a longitudinally extending core comprising at least one segment of filtering material; and optionally a wrapper encasing the longitudinally extending core; the segment of filtering material comprising sustainable filter material manufactured according to at least the following steps: a) Providing a longitudinally advancing flow of an airlaid material b) Subjecting the longitudinally advancing airlaid material to a superheated gas c) Drying the longitudinally advancing airlaid material (e.g., subsequent to subjecting the airlaid material to the superheated gas), for example by exposure to hot gas.

[0028] The method of manufacturing may further comprise the step of embossing the longitudinally advancing airlaid material (e.g., after the drying step).

[0029] The method of manufacturing may further comprise gathering laterally the longitudinally advancing airlaid material into rod form. This enables the rods to be cut into appropriate sizes to form filter segments.

[0030] The sustainable filter material may have an absorption of 4.20 mg / mg or above, for example from 4.30 mg / mg to 4.60 mg / mg, for example 4.49 mg / mg. Preferably the sustainable filter material has an absorption from 4.45 mg / mg to 4.55 mg / mg. The advantages of such sustainable filter materials are detailed above.

[0031] The sustainable filter material may have a density of 0.210 mg / mm3or less, for example from 0.200 mg / mm3to 0.210 mg / mm3, for example 0.206 mg / mm3. Preferably, the filter material has a density from 0.203 mg / mm3to 0.209 mg / mm3. The advantages of such sustainable filter materials are detailed above.

[0032] The sustainable filter material may have a tensile strength of 1 .2N or less, for example from 0.5 N to 1.2 N, for example 0.8 N. Preferably, the filter material has a tensile strength from 0.6 N to 1 .0 N. The advantages of such sustainable filter materials are detailed above. The sustainable filter material may be paper (e.g., cellulose pulp). The paper may be, for example, filter paper, non-woven paper, airlaid paper or cellulose / lyocell / viscose based paper. The paper may be a non-woven paper made with non-plastic plant based fibres (e.g., flax, hemp, jute, sisal, abaca, coconut, bamboo, starch or wood pulp) or a blend of these materials. Preferably, the sustainable filter material does not comprise cellulose acetate.

[0033] The sustainable filter material may have a basis weight from 30GSM to 200GSM, for example from 45 GSM to 120 GSM, for example 62 GSM. Preferably, the filter material has a basis weight from 50 GSM to 70 GSM.

[0034] The sustainable filter material, where the sustainable filter material is paper, may have a thickness from 100 pm to 2000 pm, for example from 300 pm to 800 pm, for example 400pm. Preferably, the paper has a thickness from 300 pm to 500 pm.

[0035] The sustainable filtering material may be embossed.

[0036] The superheated gas used in step (b) may be steam.

[0037] The steam may have a pressure from 0.5 bar to 1 .2 bar, for example from 0.6 bar to 1 bar, for example 0.8 bar. Preferably, the steam has a pressure from 0.70 bar to 0.90 bar.

[0038] The steam may have a saturation of from 100°C to 150°C, for example 110°C to 140°C, for example 120°C to 130°C. Preferably, the saturation of steam is 125°C.

[0039] The steam may be made from distilled water.

[0040] The hot gas used in step (c) may be air.

[0041] The hot gas (e.g. air) may have a temperature from 140°C to 350°C, for example from 200°C to 300°C, for example 240°C. Preferably, the temperature of hot gas (e.g. air) is from 210°C to 270°C.

[0042] According to the present invention in a third aspect there is provided a filter for use in smoking articles, aerosol generating articles, and the like, comprising a longitudinally extending core comprising at least one segment of filtering material; and optionally a wrapper encasing the longitudinally extending core; wherein the filtering material comprises a sustainable filter material having (a) an absorption of 4.20 mg / mg or above, for example from 4.30 mg / mg to 4.60 mg / mg (for example 4.49 mg / mg) wherein the absorption is measured using a capillary test; and / or (b) a density of 0.210 mg / mm3or less, for example from 0.210 mg / mm3 to 0.200 mg / mm3 (for example 0.206 mg / mm3); and / or (c) a tensile strength of 1 .2 N or less, for example from 0.5 N to 1 .2 N (for example 0.8 N). The advantages of filters including such sustainable filter materials (biodegradability, taste, user experience) are detailed above.

[0043] The sustainable filtering material may be embossed. The advantages of filters embossed sustainable filter materials are detailed above.

[0044] The sustainable filter material may be paper (e.g., cellulose pulp). The paper may be, for example, filter paper, non-woven paper, airlaid paper or cellulose / lyocell / viscose based paper. The paper may be a non-woven paper made with non-plastic plant based fibres (e.g., flax, hemp, jute, sisal, abaca, coconut, bamboo, starch or wood pulp) or a blend of these materials. Preferably, the sustainable filtering material does not comprise cellulose acetate.

[0045] The sustainable filter material may have a basis weight from 30GSM to 200GSM, for example from 45 GSM to 120 GSM, for example 62 GSM. Preferably, the sustainable filter material has a basis weight from 50 GSM to 70 GSM.

[0046] In some examples, the sustainable filter material is paper and the paper may have a thickness from 100 pm to 2000 pm, for example from 300 pm to 800 pm, for example 400pm. Preferably, the paper has a thickness from 300 pm to 500 pm.

[0047] The filter according to the third aspect of the present invention may be manufactured according to the method of the first aspect of the present invention.

[0048] Preferably the filter has a pressure drop variation from 1% to 8%, for example from 2% to 6%, for example 3% to 5%. Preferably, the filter has a pressure drop variation of 4%.

[0049] The segment of sustainable filter material may be of length 5 mm to 50 mm, for example from 20 mm to 35 mm. Preferably, the segment of sustainable filter material has a length from 15 mm to 35 mm, for example 20 mm to 30 mm. Preferably, the segment of sustainable filter material has a length of 27 mm. Preferably the filter has a length from 60 mm to 132 mm, for example from 75 mm to 120 mm, for example from 90 mm to 110 mm. Preferably, the filter has a length of 108 mm.

[0050] Preferably the circumference or perimeter of the filter is from 14 to 30 mm, e.g., from 16 to 25 mm, e.g., from 23 to 25 mm. Preferably, the circumference or perimeter of the filter is 24 mm.

[0051] The sustainable filter material (in all aspects of the invention) may be biodegradable, with greater than 90% biodegradability as measured according to ISO14855-1 Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide. Preferably the sustainable filter material exhibits a biodegradation of at least 90% after 6 months as measured according to ISO 14855-1.

[0052] Preferably the sustainable filter material has ‘Ready Biodegradability’ level of biodegradability as measured according to OECD 301 B ‘Ready Biodegradability’ method (modified Sturm test).

[0053] The sustainable filtering material may be in the form of a paper filtering material or a blend of different paper filtering materials and / or other biodegradable filtering materials. The paper may be coated with a hydrophobic coating or hydrophobic material.

[0054] The applicants have found that the use of non-woven papers (e.g., made with non-plastic plant based fibres (e.g., flax, hemp, jute, sisal, abaca, coconut, bamboo, starch or wood pulp) and / or airlaid papers are particularly suitable for production of (and use as) the sustainable filter material because they have excellent filtration properties and filtration performance, while also being biodegradable.

[0055] The applicants have found that the use of a paper (e.g., plugwrap) wrapper of basis weight from 50 to 150 gsm engaged around the segment comprising sustainable filtering material is a suitable outer wrap and may provide a firmness (i.e., hardness) similar to cellulose acetate based tubes (e.g., hollow acetate tubes), which in turn may provide the filter with a desirable firmness (i.e., hardness). Advantageously, a paper (e.g., plugwrap) wrapper of basis weight 50 to 150 gsm is biodegradable. The wrapper (e.g., plugwrap) engaged around the segment comprising sustainable filtering material may be non-porous. Alternatively, the wrapper (e.g., plugwrap) engaged around the segment comprising sustainable filtering material may be ventilated or air permeable, with an air permeability of from 0 to 32,000 Coresta units.

[0056] A filter according to the invention (or a filter which includes sustainable filter material manufactured according to the invention) may be adjoined to a wrapped plug of tobacco (e.g. wrapped plug of modified tobacco, as is well known in the art). The filter may be adjoined to the wrapped tobacco plug by ring tipping (i.e. an outer wrapper (e.g. tipping paper) which engages around just the adjacent ends of the wrapped filter and the tobacco plug to leave much of the filter wrap exposed). The filter may be adjoined to the wrapped tobacco plug by a full tipping overwrap (i.e. an outer wrapper (e.g. tipping paper) which engages around the full wrapped filter length and the adjacent end of the tobacco plug).

[0057] The wrapper (e.g. filter wrapper) may be ventilated by e.g. laser perforations. The ventilation may be applied to the wrapper (e.g. filter wrapper) before or after the filter is adjoined to the wrapped tobacco plug. The ventilation may be (applied to the wrapper) in register with a cavity in the filter (if present).

[0058] The present invention will now be described in further detail by reference to the attached Figures in which:

[0059] Figure 1 shows a schematic side view of an apparatus for manufacturing filters according to the first aspect of the invention;

[0060] Figure 2 shows a schematic view of one embodiment of the invention, an example filter of the second and third aspects of the invention comprising a segment of the sustainable filter material;

[0061] Figure 3 shows a schematic view of another embodiment of the invention, a filter comprising at least one segment of the sustainable filter material;

[0062] Figure 4 shows a schematic view of another embodiment of the invention, a filter comprising at least one segment of the sustainable filter material; Figure 5 shows a graph of experimental data of the percent pressure drop variation at a given filter pressure drop for a filter according to the present invention compared to a reference filter;

[0063] Figure 6 illustrates a graph showing experimental data of total filter pressure drop at given filter material crimp depth for a filter according to the present invention compared to a reference filter.

[0064] Figure 1 shows an apparatus for forming filters using non-woven material, a process well known in the art, which has been adapted to form the filter of the present invention by the method of the present invention. The apparatus makes filters from a bale comprising airlaid non-woven paper filtering material 102 of thickness of roughly 1 .3 mm and a width of roughly 1 .3 mm. The airlaid material is drawn from the bale 102 by a paper drive unit 104 to form a longitudinally advancing tow of filter material 106. The tow of filter material 106 is then fed into a paper stabiliser and splitter 108. The filter material 106 is advanced through the paper stabiliser and splitter 108 by a first set of rollers 110.

[0065] A second, downstream, set of rollers 112, which rotate faster than the first set of rollers 110, stretch the tow of filter material 106 between the first 110 and second 112 sets of rollers. The tow of filter material is then fed into a steam box 114. Within the steam box 114, the tow of filter material 106 is subjected to superheated steam of a pressure from 0.5 bar to 1 .2 bar and a saturation from 100°C to 150°C, for example 110°C to 140°C, for example 120°C to 130°C. Preferably, the saturation of steam is 125°C .

[0066] The tow of filter material 106 which has been steam treated is stretched again by a third set of rollers 116 rotating faster than the second set of rollers 112. The tow of filter material 106 is fed through a hot air blow chamber 118 to be dried. The temperature of the hot air in hot air blow chamber 118 is from 140°C to 350°C. Once dried, the tow of filter material 106 is fed through an embossing roller 120 which crimps the filter material 106 to a depth from 0.4 mm to 0.8 mm. The embossed / crimped filter material 106 is drawn through a paper cone 122.

[0067] A strip of plugwrap 124 drawn continuously from a reel 126 is drawn past a hot melt applicator 128 which applies hot melt adhesive to the plugwrap 124. The plugwrap with adhesive 130 is then drawn into a garniture unit 132 along with the filter material 106 that has been passed through the paper cone 122. In the garniture unit 132, the tow of filter material 106 is shaped to rod form, and the plugwrap with adhesive 130 is wrapped around the filter material 106. The plugwrap 130 is fixed around the tow of filter material 106 with a lapped and stuck seam.

[0068] The continuously produced wrapped rod 134 then passes through a cutting unit 136 which severs the rod 134 into individual filter element lengths (not shown) which continue into a transfer unit 138 and finally end up on a packing table 140.

[0069] Figure 2 illustrates an schematic view of one possible embodiment of a filter 200 according to the present invention, with all components visible. The filter 200 includes a mouth end 202 and a longitudinally extending core of sustainable filtering material 204. The longitudinally extending core of sustainable filtering material 204 has a length of 27 mm and a circumference of 24 mm. The longitudinally extending core of sustainable filter material 204 is formed from airlaid material which is gathered laterally into rod form and held in place by a first wrapper 206 of non-porous plugwrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 GSM weight. The filter of Figure 2 is manufactured according to the method described in Figure 1 and has Tensile Strength 0.8 N, Absorption 4.49 mg / mg and Density 0.206 mg / mm3. The applicants found that the sustainable filter material having been subjected to superheated steam, dried by hot air, and then embossed provided a reduced variance in pressure drop across the filter of Figure 2 (see Examples below). Furthermore, the absorption of the sustainable filter material was found to be increased which resulted in the filter according to Figure 2 having an improved taste quality in use due to increased absorption of the user’s saliva by the filter. The filter of Figure 2 was also found to have a reduced tear resistance which, when combined with the increased absorption, resulted in the filter being more readily biodegradable.

[0070] A further filter wrapper 208 of stiff plugwrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 GSM weight (please provide weight if necessary) encases the wrapped longitudinally extending core 204. Both ends of the wrapped filter 200 are flush with the wrapped longitudinally extending core 204. The filter wrapper 208 has an overlapping longitudinal edge with adhesive applied thereon which provides a lapped and stuck seam (not shown) holding the filter wrapper 208 around the wrapped longitudinally extending core 204 and a further adhesive in anchor lines (not shown) in register with the wrapped longitudinally extending core 204 to hold the longitudinally extending core 204 in place. The filter 200 may be joined, at the end opposite the mouth end 202, to a wrapped plug of tobacco, by methods well known in the art. A suitable plug of tobacco is 11 mm to 40 mm long, preferably 27 mm long, and has a circumference from 15 mm to 30 mm. Such plugs of tobacco are well known in the art. Together the filter 200 and plug of tobacco form a smoking article including the sustainable filter material of the present invention.

[0071] Figure 3 illustrates a schematic view of a filter 300 comprising a first longitudinally extending core 302 and a second longitudinally extending core 304 adjacent (e.g. abutted to) to one end of the first longitudinally extending core 302 of length 27 mm . The first longitudinally extending core 302 comprises a first filtering material in the form of a sheet of embossed paper [airlaid non-woven paper filtering material of thickness of about 1 .3 mm and of width of about 1 .3 mm ] with activated carbon granules embedded therein at a loading of 4.9 mg activated carbon / mm, which is gathered into rod form and held in place with a first core wrapper 306 of non-porous plug wrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 gsm. The first longitudinally extending core 302 is made by methods well known in the art: for example, the embossed paper may have activated carbon applied thereto and embedded therein by means of a roller or rollers, and is then gathered into rod form and secured in place (e.g., by a lapped and stuck seam as is known in the art) with a first core wrapper 306 (e.g., a wrapper, e.g., a plug wrap) engaged around the rod.

[0072] The second longitudinally extending core 304 comprises a sustainable filter material, of length 27 mm, manufactured according to the present invention (e.g. by the method described above with reference to Fig 1). The sustainable filter material is gathered laterally into rod form and held in place, along with the wrapped first longitudinally extending core 302, by a wrapper 308 of non-porous plugwrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 GSM weight.

[0073] A further filter wrapper 310 of stiff plugwrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 GSM weight encases the first 302 and second 304 longitudinally extending cores. Both ends of the wrapped filter 300 are flush with the first 302 and second 304 longitudinally extending cores. The filter wrapper 310 has an overlapping longitudinal edge with adhesive applied thereon which provides a lapped and stuck seam (not shown) holding the filter wrapper 310 around the first 302 and second 304 longitudinally extending cores and a further adhesive in anchor lines (not shown) in register with the first 302 and second 304 longitudinally extending cores to hold the first 302 and second 304 longitudinally extending cores in place.

[0074] Figure 4 illustrates a schematic view of a filter 400 comprising a first longitudinally extending core 402 and a second longitudinally extending core 404. Both the first 402 and second 404 longitudinally extending cores comprise a sustainable filter material manufactured according to the present invention (e.g. by the method described above with reference to Fig 1 ). The sustainable filter material is gathered laterally into rod form. A filter wrapper 406 of stiff plugwrap [Mudanjiang Hengfeng Paper Co., Ltd of Mundanjiang, China] of 78 GSM weight encases the first 402 and second 404 longitudinally extending cores such that the filter wrapper 406 defines a cavity 408 between the first 402 and second 404 longitudinally extending cores.

[0075] The filter wrapper 406 has an overlapping longitudinal edge with adhesive applied thereon which provides a lapped and stuck seam (not shown) holding the filter wrapper 406 around the first 402 and second 404 longitudinally extending cores and a further adhesive in anchor lines (not shown) in register with the first 402 and second 404 longitudinally extending cores to hold the first 402 and second 404 longitudinally extending cores in place.

[0076] Experiment

[0077] A sustainable filter material made according to the invention was subjected to numerous tests to determine its performance in areas such as tear resistance, absorption, pressure variation etc. The reference product included the airlaid paper that was not subjected to superheated steam and hot air.

[0078] The tensile strength was assessed by using the ASTM D689-17 test which is well known in the art. The stationary and movable clamp method was used and provided the data as set out in Table 1.

[0079] Table 1 : Tensile Strength Test Data As seen in Table 1 , the tensile strength of the sustainable filter material made according to the invention (airlaid material that has been subjected to superheated steam and dried with hot air) is noticeably lower than the reference airlaid paper material. The applicants found that this leads to a reduced tear resistance which reduced the rates of defects in all products, made the smoke delivery to the user more stable, and made the material more sustainable as it is more readily biodegradable.

[0080] The absorption of the sustainable filter material was assessed and compared to the reference material using a capillary test, a paper absorption test well known in the art. The data is set out in Table 2 below.

[0081] Table 2: Absorption Test Data

[0082] As seen in Table 2 , the absorption of the sustainable filter material made according to the present invention is noticeably higher than the reference airlaid paper material. The applicants found that an increase in absorption of the sustainable filter material provided better taste quality as the user’s saliva was less present on the mouth section of the filter material.

[0083] The density of the sustainable filter material was assessed and compared to the reference material. The data is set out in Table 3 below.

[0084] Table 3: Density Test Data

[0085] As seen in Table 3, the density of the sustainable filter material made according to the invention is less than the reference airlaid paper material. The applicants found that a reduced density of the sustainable filter material due to the manufacturing process enabled the sustainable filter material to fill the filter space more efficiently with the material fibers distributed more evenly across the filter. This surprisingly led to a decreased pressure drop variation across the filter, as shown in Figure 5. The applicants also assessed the effect on total filter pressure drop by differing crimping depths of the sustainable filter material. These results were also assessed against the reference material which was subject to the same crimping depths. The data is set out in Figure 6

[0086] As seen in Figure 6, the sustainable filter material made by methods of the invention offers slightly reduced pressure drop at each given crimp depth when compared to the reference material. However, when taken in conjunction with the data from Figure 5, the pressure drop variation at each crimp depth (0.6 mm and 0.7 mm) is significantly lower when filters are made from the sustainable filter material. The applicants found that this resulted in filters made from the sustainable filter material having more stable smoke delivery and therefore a better user experience.

Claims

CLAIMS1 . A method of manufacturing a sustainable filter material for use in smoking articles, aerosol generating articles and the like, the method comprising the steps of: a) Providing a longitudinally advancing flow of an airlaid material; b) Subjecting the longitudinally advancing airlaid material to a superheated gas; and c) Drying the longitudinally advancing airlaid material (e.g., subsequent to subjecting the airlaid material to the superheated gas), e.g. by exposure to hot gas.

2. A method according to claim 1 further comprising the step of embossing the longitudinally advancing airlaid material (e.g., after the drying step).

3. A method according to claim 1 or claim 2 further comprising gathering laterally the longitudinally advancing airlaid material into rod form.

4. A method according to any preceding claim in which the sustainable filter material has an absorption of 4.20 mg / mg or above, for example from 4.30 mg / mg to 4.60 mg / mg (for example 4.49 mg / mg) wherein the absorption is measured using a capillary test5. A method according to any preceding claim in which the sustainable filter material has a density of 0.210 mg / mm3or less, for example from 0.200 mg / mm3to 0.210 mg / mm3(for example 0.206 mg / mm3).

6. A method according to any preceding claim in which the sustainable filter material has a tensile strength of 1 .2 N or less, for example from 0.5 N to 1 .2 N (for example 0.8 N).

7. A method according to any preceding claim in which the sustainable filter material is paper (i.e., cellulose pulp).

8. A method according to any preceding claim in which the sustainable filter material has basis weight is from 30GSM to 200GSM (for example 62GSM).

9. A method according to any preceding claim in which the sustainable filter material comprises paper wherein the thickness of the paper is from 100 pm to 2000 pm (for example 400pm).

10. A method according to any preceding claim in which the superheated gas is steam.11 . A method according to claim 10 in which the pressure of the steam is from 0.5 bar to 1 .2 bar (for example 0.8 bar)12. A method according to claim 10 or 11 in which the saturation of the steam is from 100°C to 150°C (for example 125°C).

13. A method according to any of claims 10 to 12 in which, the steam is made from distilled water.

14. A method according to any preceding claim in which the hot gas is air.

15. A method according to claim 14 in which the temperature of the air is from 140°C to 350°C (for example 240 °C).

16. A filter for use in smoking articles, aerosol generating articles, and the like, comprising a longitudinally extending core comprising at least one segment of filtering material; and optionally a wrapper encasing the longitudinally extending core; the segment of filtering material comprising sustainable filter material manufactured according to at least the following steps: a) Providing a longitudinally advancing flow of an airlaid material b) Subjecting the longitudinally advancing airlaid material to a superheated gas c) Drying the longitudinally advancing airlaid material (e.g., subsequent to subjecting the airlaid material to the superheated gas), for example by exposure to hot gas.

17. A filter according to claim 16 wherein the sustainable filter material has an absorption of 4.20 mg / mg or above, for example from 4.30 mg / mg to 4.60 mg / mg (for example 4.49 mg / mg) wherein the absorption is measured using a capillary test.

18. A filter according to claim 16 wherein the sustainable filter material has a density of 0.210 mg / mm3or less, for example from 0.200 mg / mm3to 0.210 mg / mm3(for example 0.206 mg / mm3).

19. A filter according to claim 16 wherein the sustainable filter material has a tensile strength of 1 .2N or less, for example from 0.5 N to 1 .2 N (for example 0.8 N).

20. A filter according to any of claims 16 to 19, wherein the sustainable filter material is paper (i.e., cellulose pulp).21 . A filter according to any of claims 16 to 20, wherein the sustainable filter material has a basis weight is from 30GSM to 200GSM (for example 62GSM.

22. A filter according to any of claims 16 to 21 , wherein the sustainable filter material is paper and the thickness of the paper is from 100 pm to 2000 pm (for example 400pm).

23. A filter according to any of claims 16 to 22 wherein the superheated gas is steam.

24. A filter according to claim 23, wherein the pressure of the steam is from 0.5 bar and 1 .2 bar (for example 0.8 bar)25. A filter according to claims 23 or 24, wherein the saturation of the steam is from 100°C to 150°C (for example 125°C).

26. A filter according to any of claims 23 to 25 wherein the steam is made from distilled water27. A filter according to any of claims 16 to 26 wherein the hot gas is air.

28. A filter according to claim 27, wherein the temperature of the air is from 140°C to 350°C (for example 240 °C).

29. A filter for use in smoking articles, aerosol generating articles, and the like, comprising a longitudinally extending core comprising at least one segment of filtering material; and optionally a wrapper encasing the longitudinally extending core;wherein the filtering material comprises a sustainable filter material having (a) an absorption from 4.30 mg / mg to 4.60 mg / mg (for example 4.49 mg / mg) wherein the absorption is measured using a capillary test; and / or (b) a density from 0.210 mg / mm3to 0.200 mg / mm3(for example 0.206 mg / mm3); and / or (c) a tensile strength from 0.5 N to 1 .2 N (for example 0.8 N).

30. A filter according to Claim 29, wherein the sustainable filter material is paper (i.e. , cellulose pulp).31 . A filter according to any of Claims 29 or 30, wherein sustainable filter material has a basis weight from 30GSM to 200GSM (for example 62GSM.

32. A filter according to any of Claims 29 to 31 , wherein the sustainable filter material is paper and the thickness of the paper is from 100 pm to 2000 pm (for example 400pm).

33. A filter according to any of Claims 29 to 32, wherein the sustainable filter material is manufactured according to the method of any of claims 1 to 15.

34. A filter according to any of claims 29 to 33, wherein the filter has a pressure drop variation of from 25 mmHg to 80 mmHg (for example 47 mmHg) across the filter..

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