Filter segment with heavy filter wrapper for aerosol-generating article

Abstract

A filter segment for an aerosol-generating article, comprises a plug of filter material and a filter wrapper. The plug of filter material extends along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material. The filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material. The wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube. An axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube. An axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube. At least a portion of the filter wrapper has a grammage of at least 120 grams per square meter.

Description

[0001] Filter segment with heavy filter wrapper for aerosol-generating article

[0002] The present disclosure relates to filter segments for aerosol-generating articles.

[0003] US20160128378A1 discloses a smoking article comprising a tobacco rod and a filter comprising a plug of filtration material that defines a downstream end segment of the smoking article. Tipping material attaches the tobacco rod and the filter. Examples of materials for the filtration material include cellulose acetate, cellulose, reconstituted cellulose, polylactic acid, polyvinyl alcohol, nylon, polyhydroxybutyrate, thermoplastic material, such as starch, non-woven materials, longitudinally oriented fibers and randomly oriented fibers, paper, crepe, PEA fires, and combinations thereof. The plug of filtration material is surrounded by one or more filter wrappers. The one or more filter wrappers have a basis weight between about 50 grams per square meter and about 100 grams per square meter. US20160128378A1 discloses that the use of a filter wrapper having a basis weight of about 78 grams per square meter sufficiently increases the hardness of the smoking article, while avoiding the need for a very stiff filter wrapper, which may make manufacture more difficult.

[0004] EP3033952A1 discloses a device for manufacturing a double-layered tube for the tobacco industry. A cutting device cuts a basic material strip along a longitudinal axis into a first material strip having a first width and a second material strip having a second width. An adhesive is applied to the first material strip and / or the second material strip. The first and second material strips are combined such that they are provided above each other in an offset manner. A tubular strand is formed from the combined first and second material strips. The tubular strand is provided to a filter strand machine to position a filter material around the tubular strand or into the tubular strand.

[0005] WO2021 105856A1 discloses an aerosol generating substrate element comprising a cylindrical aerosol generating substrate, a first paper wrapper and a second paper wrapper. The first paper wrapper comprises opposing edges that abut each other to circumscribe the aerosol forming substrate and form a first seam line. The second paper wrapper comprises opposing edges that abut each other to circumscribe the first paper wrapper and form a second seam line. The first seam line is offset from the second seam line and the first paper wrapper and the second paper wrapper do not extend beyond the aerosol generating substrate.

[0006] According to an aspect of the invention, there is provided a filter segment for an aerosolgenerating article. The filter segment comprises a plug of filter material and a filter wrapper. The plug of filter material extends along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material. The filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material. The wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube. An axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube. An axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube. At least a portion of the filter wrapper has a grammage of at least 120 grams per square meter.

[0007] The filter wrapper may increase a hardness of the filter segment. The filter wrapper may make the filter segment more resilient to compressive forces, in particular to compressive forces exerted by a mouth of a user. The filter wrapper may at least partially counteract a deformation of the plug of filter material. The filter wrapper may contribute to a tendency of the filter segment to return to its original shape after compression of the filter segment.

[0008] A high-grammage filter wrapper may allow using a softer material for the plug of filter material, while still obtaining a desired overall hardness of the filter segment.

[0009] The portion of the filter wrapper may have a grammage of at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0010] The portion of the filter wrapper may have a grammage below 800 grams per square meter, or below 600 grams per square meter, or below 500 grams per square meter, or below 400 grams per square meter, or below 300 grams per square meter, or below 260 grams per square meter, or below 240 grams per square meter, or below 200 grams per square meter.

[0011] The portion of the filter wrapper may have a grammage between 120 grams per square meter and 400 grams per square meter, or between 120 grams per square meter and 300 grams per square meter, or between 120 grams per square meter and 260 grams per square meter, or between 120 grams per square meter and 240 grams per square meter, or between 120 grams per square meter and 200 grams per square meter, or between 140 grams per square meter and 260 grams per square meter, or between 260 grams per square meter and 260 grams per square meter.

[0012] The portion of the filter wrapper may have a uniform grammage.

[0013] The portion of the filter wrapper may comprise at least 60 percent, or at least 70 percent, or at least 80 percent, or at least 90 percent of a total area of the filter wrapper. The portion of the filter wrapper may be a coherent portion of the filter wrapper. The portion of the filter wrapper may comprise a totality of the area of the filter wrapper, where the filter wrapper does not overlap on itself due to being wrapped around the plug of filter material.

[0014] The filter wrapper may comprise a single wrapper layer. The single wrapper layer may have a grammage of at least 120 grams per square meter.

[0015] The filter wrapper may comprise at least two wrapper layers provided radially above each other. If the filter wrapper comprises more than one wrapper layer provided radially above each other, the need to manufacture or provide a single layer having sufficient grammage or thickness may be avoided. Manufacturing a layer having certain desired properties may be easier for lower thicknesses of the layer than for higher thicknesses of the layer. By providing two wrapper layers radially above each other, comparatively thinner layers may be manufactured having the desired properties, but still allowing for a higher thickness or grammage of the filter wrapper in total. For example, thinner layers may be manufactured having a higher porosity than thicker layers. Thus, when the filter wrapper comprises multiple wrapper layers provided radially above each other, obtaining a high porosity filter wrapper may be facilitated as compared to a filter wrapper having the same thickness but only a single wrapper layer. High porosity may be desirable to improve adhesion of adhesives, such as glue, to the wrapper layer.

[0016] The at least two wrapper layers may be formed by separate sheets or may be formed by a single sheet folded to provide at least two wrapper layers superimposed on each other, for example.

[0017] The filter wrapper may comprise a laminate of at least two wrapper layers provided radially above each other. The at least two wrapper layers may be laminated to each other using an adhesive or a glue.

[0018] According to another aspect of the invention, there is provided a filter segment for an aerosol-generating article. The filter segment comprises a plug of filter material and a filter wrapper. The plug of filter material extends along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material. The filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material. The wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube. An axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube. An axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube. The filter wrapper comprises at least two wrapper layers provided radially above each other, in particular a laminate of at least two wrapper layers provided radially above each other.

[0019] The filter wrapper may have a first edge region, a second edge region, and a main region provided between the first edge region and the second edge region. The first edge region may overlap the second edge region to close the wrapper tube. The filter wrapper overlapping on itself may facilitate that the filter wrapper fully surrounds the plug of filter material along the circumferential direction. The portion of the filter wrapper having the grammage of at least 120 grams per square meter may comprise the main region of the filter wrapper. The main region of the filter wrapper may extend along an entire length of the filter wrapper along the axial direction. The first edge region may comprise a first edge of the filter wrapper. The second edge region may comprise a second edge of the filter wrapper. The first edge and the second edge may be parallel to each other. The first edge and the second edge may be parallel to the axial direction. The first edge region may be provided radially outwards of the second edge region. The second edge region may be provided radially inwards of the first edge region.

[0020] The first edge region and the second edge region may be fixed to each other by an adhesive. The adhesive may be a glue or may comprise a glue. The adhesive may be sandwiched between the first edge region and the second edge region along a radial direction.

[0021] A width of an overlap of the filter wrapper, in particular of an overlap of the first edge region and the second edge region of the filter wrapper, along the circumferential direction may be between 1 millimeter and 5 millimeters, or between 2 millimeters and 4 millimeters, or between 2 millimeters and 3 millimeters.

[0022] The filter wrapper may have a uniform thickness. A filter wrapper having a uniform thickness may comprise a single wrapper layer or multiple wrapper layers provided radially above each other. In embodiments with a filter wrapper having a uniform thickness, a wall thickness of the wrapper tube may still be non-uniform. For example, a wall thickness of the wrapper tube in a region where the filter wrapper overlaps itself, in particular where the first edge region and the second edge region of the filter wrapper overlap, may be greater than a wall thickness of a wrapper tube at points where the filter wrapper does not overlap itself.

[0023] The filter wrapper may have a non-uniform thickness.

[0024] One or both of the first edge region and the second edge region may have a smaller thickness than the main region. As compared to a filter wrapper having a uniform thickness, a bulge of the wrapper tube at the overlap between the first edge region and the second edge region may be reduced or avoided, if the thickness of the filter wrapper is reduced in one or both of the first edge region and the second edge region.

[0025] One of the first edge region and the second edge region may have a smaller thickness than the main region and the other one of the first edge region and the second edge region may have a same thickness as the main region.

[0026] A thickness of the first edge region may be the same as a thickness of the second edge region. The thickness of the first edge region may be the same as the thickness of the second edge region both in embodiments where the filter wrapper has a uniform thickness and in embodiments where the thickness of the first edge region and the second edge region is reduced compared to a thickness of the main region.

[0027] A thickness of the first edge region may be different from a thickness of the second edge region. For example, both of the thickness of the first edge region and the thickness of the second edge region may be smaller than a thickness of the main region, but may differ from each other.

[0028] The first edge region may be recessed with respect to the main region. The recess of the first edge region may face towards an inside of the filter segment, in particular along a radial direction. A surface of the first edge region radially opposite of the recess of the first edge region may be flush with the main region. The second edge region may be recessed with respect to the main region. The recess of the second edge region may face towards an outside of the filter segment, in particular in a radial direction. A surface of the second edge region radially opposite the recess of the second edge region may be flush with the main region.

[0029] A combined thickness of the first edge region and the second edge region may be less than 150 percent of a thickness of the main region.

[0030] A combined thickness of the first edge region and the second edge region may correspond to a thickness of the main region. If the combined thickness of the first edge region and the second edge region essentially correspond to a thickness of the main region, an outer surface of the wrapper tube may be essentially smooth or essentially bulge-free.

[0031] For a filter wrapper having at least two wrapper layers provided radially above each other, a reduced thickness of one or both of the first edge region and the second edge region compared to the main region may be provided by way of at least one of the wrapper layers not extending along the full width of the filter wrapper along the circumferential direction. Circumferential ends of different wrapper layers of the at least two wrapper layers may be circumferentially offset with respect to each other. Widths along the circumferential direction of the at least two wrapper layers may be the same for all wrapper layers of the filter wrapper (or for at least two of the wrapper layers of the filter wrapper) or may be different for different wrapper layers of the filter wrapper.

[0032] One or both of the first edge region and the second edge region may be free of at least one of the at least two wrapper layers of the filter wrapper.

[0033] The first edge region may be free of at least one first wrapper layer of the at least two wrapper layers of the filter wrapper. The at least one first wrapper layer may form part of the main region. The at least one first wrapper layer may form part of the second edge region. The at least one first wrapper layer may form part of the main region and of the second edge region. The at least one first wrapper layer may be at least one innermost wrapper layer of the filter wrapper with respect to the radial direction.

[0034] The second edge region may be free of at least one second wrapper layer of the at least two wrapper layers of the filter wrapper. The at least one second wrapper layer may form part of the main region. The at least one second wrapper layer may form part of the first edge region. The at least one second wrapper layer may form part of the main region and of the first edge region. The at least one second wrapper layer may be at least one outermost wrapper layer of the filter wrapper.

[0035] A thickness of the at least one first wrapper layer may be the same as a thickness of the at least one second wrapper layer.

[0036] A width of the first edge region along the circumferential direction may correspond to a width of the second edge region along the circumferential direction. A thickness of the at least one first wrapper layer may correspond to a thickness of the main region of the filter wrapper minus a thickness of the at least one second wrapper layer. The first edge region and the second edge region may overlap so that a combined thickness of the first edge region and the second edge region corresponds to a thickness of the main region, preferably avoiding a bulge due to the overlap.

[0037] The filter wrapper may comprise a sheet or may be formed of a sheet material. The sheet may comprise a single layer or at least two layers.

[0038] A thickness of the filter wrapper may be below 200 micrometers, or below 150 micrometers, or below 100 micrometers. A thickness of the filter wrapper may be more than 50 micrometers, or more than 80 micrometers, or more than 100 micrometers. A thickness of the filter wrapper may be between 50 micrometers and 200 micrometers, or between 80 micrometers and 150 micrometers.

[0039] The plug of filter material may fill the wrapper tube along an entire length of the wrapper tube along the axial direction.

[0040] The plug of filter material may be in contact with an inner surface of the wrapper tube. The plug of filter material may be in direct contact with the filter wrapper. The filter wrapper may be wrapped around the plug of filter material without an intermediate layer between the plug of filter material and the filter wrapper.

[0041] An adhesive layer may be provided on an inner surface of the wrapper tube. The adhesive layer may be in contact with both the inner surface of the wrapper tube and an outer surface of the plug of filter material. The adhesive layer may fix the plug of filter material with respect to the filter wrapper to counteract relative movement of the plug of filter material with respect to the wrapper tube along the axial direction.

[0042] The filter wrapper may comprise biodegradable material or consist of biodegradable material. Using biodegradable material may contribute to providing an environment friendly aerosol-generating article.

[0043] The filter wrapper may comprise one or more of paper, cardboard, carton, airlaid and nonwoven. The filter wrapper may comprise paper, or cardboard, or carton, or airlaid, or nonwoven. The filter wrapper may consist of one or more of paper, cardboard, carton, airlaid, and nonwoven. The filter wrapper may consist of paper, or cardboard, or carton, or airlaid, or nonwoven.

[0044] The plug of filter material may be a unitary structure. The plug of filter material may be a one-piece element.

[0045] The plug of filter material may be rod-shaped. The plug of filter material may be cylindrically shaped. The opposing base surfaces of the cylinder shape of the plug of filter material may oppose each other along the axial direction. The opposing base surfaces of the cylinder shape of the plug of filter material may be perpendicular to the axial direction. The plug of filter material may be made from biodegradable material, or comprise biodegradable material, or consist of biodegradable material.

[0046] The plug of filter material may comprise one or both of cellulose and paper. The cellulose may be regenerated cellulose. The plug of filter material may consist of paper. The plug of filter material may comprise a tow comprising regenerated cellulose filaments, or paper, or regenerated cellulose, for example. The plug of filter material may comprise paper-like sheets comprising cellulose. The plug of filter material may comprise a web or sheet material, in particular a crimped web or sheet material. The web or sheet material may comprise or consist of paper or non-woven material made with cellulose and / or a mix of cellulose with regenerated cellulose.

[0047] The plug of filter material may be free of cellulose acetate. Any loss in hardness of the filter segment from replacing cellulose acetate filter plugs with softer filter plugs may be compensated by the high grammage of the filter wrapper.

[0048] The plug of filter material may have an air filtering capability. The plug of filter material may be configured to filter air flowing through the plug of filter material along the axial direction.

[0049] The plug of filter material may comprise a cellulosic filtration material or consist of a cellulosic filtration material. The cellulosic filtration material may be free of cellulose acetate. The cellulosic filtration material may comprise a paper material. The cellulosic filtration material may comprise a nonwoven paper material. The cellulosic filtration material may comprise a fibrous material comprising a plurality of regenerated cellulose fibres. The regenerated cellulose fibres may be one or more of viscose fibres, modal fibres, Lyocell fibres and viscose rayon fibres. The cellulosic filtration material may comprise a fibrous material comprising a plurality of natural fibres. The natural fibres may be one or more of flax fibres, hemp fibres, jute fibres, kenaf fibres, ramie fibres, abaca fibres, phormium fibres, sisal fibres, coir fibres, cotton fibres, and kapok fibres.

[0050] A hardness of the plug of filter material may be below 20 percent. The hardness of the plug of filter material may be between 0 percent and 20 percent, or between 5 percent and 20 percent, for example. A hardness of the filter segment may be at least 85 percent. The hardness of the filter segment may be between 85 percent and 98 percent, or between 90 percent and 98 percent, for example.

[0051] According to another aspect of the present invention, there is provided an aerosolgenerating article. The aerosol-generating article comprises the filter segment. The aerosolgenerating article further comprises one or more additional segments and a tipping paper. The one or more additional segments may comprise an aerosol-generating segment with an aerosolgenerating substrate. The tipping paper may be at least partially wrapped around the filter segment and at least partially wrapped around at least one of the one or more additional segments.

[0052] The tipping paper may combine the filter segment and the at least one of the one or more additional segments. The tipping paper may be wrapped around at least a part of the aerosol- generating segment. The tipping paper may form at least a part of an outer surface of the aerosolgenerating article.

[0053] The aerosol-generating substrate may comprise one or more alkaloids. The aerosolgenerating substrate may comprise tobacco. The aerosol-generating substrate may comprise nicotine. The aerosol-generating substrate may comprise reconstituted tobacco material.

[0054] The aerosol-generating article may be a cigarette providing an aerosol by burning. Alternatively, the aerosol-generating article may be configured for use within aerosol-generating device to generate aerosol for consumption by a user without burning. The aerosol-generating article may be a heat-not-burn article. The aerosol-generating article may be configured to be heated by the aerosol-generating device to generate the aerosol. The aerosol-generating segment may be configured to be heated by a heater of the aerosol-generating device, in particular by an electric heater of the aerosol-generating device. The aerosol-generating segment may comprise a susceptor element configured to be heated by being subjected to an alternating magnetic field generated by the aerosol-generating device.

[0055] The filter segment and the one or more additional segment may be arranged one behind the other in the aerosol-generating article. The one or more additional segments may comprise only the aerosol-generating segment. The one or more additional segments may comprise at least one additional segment in addition to the aerosol-generating segment. The one or more additional segments may comprise one or both of a cooling and spacing segment, and a front plug segment. The cooling and spacing segment may be provided between the filter segment and the aerosolgenerating segment. Aerosol-generated at the aerosol-generating segment may traverse the cooling and spacing segment on its way to the filter segment, whereby the aerosol may cool down to some degree.

[0056] The filter segment may be provided at a proximal end of the aerosol-generating article. The optional front plug segment may be provided at the opposing distal end of the aerosol-generating article.

[0057] According to another aspect of the present invention, there is provided a method for manufacturing filter segments. A rod of filter material is provided. At least two wrapper layers are provided. The at least two wrapper layers are combined into a web of filter wrapper. Subsequently, the web of filter wrapper is wrapped around the rod of filter material.

[0058] Combining the at least two wrapper layers into the web of filter wrapper may enable using a filter wrapper having an increased thickness, but still having at least some of the material properties of the thinner wrapper layers. The filter wrapper comprising the at least two wrapper layers may have an increased grammage as compared to the individual wrapper layers.

[0059] The at least two wrapper layers may comprise a first wrapper layer and a second wrapper layer. The first wrapper layer and the second wrapper layer may be formed of the same material. The first wrapper layer may comprise a different material than the second wrapper layer. The first wrapper layer and the second wrapper layer may provide different properties of the filter wrapper.

[0060] The method may further comprise cutting the wrapped rod of filter material into filter segments. During cutting, the web of filter wrapper may be separated into individual filter wrappers, wherein each filter segment may comprise one filter wrapper. During cutting, the rod of filter material may be separated into individual plugs of filter material. Each filter segment may comprise one plug of filter material.

[0061] At least a portion of the web of filter wrapper may have a grammage of at least 120 grams per square meter, or at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0062] The at least two wrapper layers may be formed by separate webs or may be formed by a single web folded to provide at least two wrapper layers superimposed on each other, for example.

[0063] Combining the at least two wrapper layers into the web of filter wrapper may comprise laminating the at least two wrapper layers material to each other.

[0064] The at least two wrapper layers may comprise at least one wrapper layer having a first width and at least one wrapper layer having a second width different from the first width. Alternatively, all wrapper layers of at least two wrapper layers may have a same width.

[0065] At least two of the wrapper layers may be combined in an offset manner with respect to a width direction.

[0066] Wrapping the web of filter wrapper around the rod of filter material may be done such that the web or a filter wrapper forms a wrapper tube around the rod of filter material. The web of filter wrapper may be wrapped around the rod of filter material while the rod of filter material and the web of filter wrapper are conveyed along a production direction.

[0067] According to another aspect of the present invention, there is provided a method for manufacturing filter segments. A rod of filter material is provided. A web of filter wrapper is wrapped around the rod of filter material such that the web or a filter wrapper forms a wrapper tube around the rod of filter material, while the rod of filter material and the web of filter wrapper are conveyed along a production direction. The wrapped rod of filter material is cut into filter segments. At least a portion of the web of filter wrapper has a grammage of at least 120 grams per square meter.

[0068] The portion of the web of filter wrapper may have a grammage of at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0069] The web of filter wrapper may comprise a single wrapper layer. The web of filter wrapper may comprise at least two wrapper layers. The at least two wrapper layers may be provided radially above each other after forming of the wrapper tube.

[0070] The web of filter wrapper may comprise a laminate of the at least two wrapper layers.

[0071] The web of filter wrapper may have a first lateral edge region, a second lateral edge region, and a main region provided between the first lateral edge region and the second lateral edge region. Wrapping the web of filter wrapper around the rod of filter material may comprise overlapping the first lateral edge region over the second lateral edge region. Overlapping the first lateral edge region over the second lateral edge region may close the continuous wrapper tube.

[0072] The method may comprise applying a pressure onto an overlap between the first lateral edge region and the second lateral edge region. The pressure may compress one or both of the rod of filter material and the filter wrapper in the region of the overlap of the filter wrapper. The pressure may increase an adhesion between the first lateral edge region and the second lateral edge region. The pressure may reduce a bulge of the filter wrapper at the overlap between the first lateral edge region and the second lateral edge region.

[0073] An adhesive may be applied to at least one of the first lateral edge region and the second lateral edge region before overlapping the first lateral edge region over the second lateral edge region. The adhesive may be provided between the first lateral edge region and the second lateral edge region after the overlapping. The adhesive may be in contact with both the first lateral edge region and the second lateral edge region after the overlapping. The adhesive may attach the first lateral edge region and the second lateral edge region to each other. The adhesive may comprise a glue.

[0074] A width of an overlap between the first lateral edge region and the second lateral edge region along the circumferential direction may be between 1 millimeter and 5 millimeters, or between 2 millimeters and 4 millimeters, or between 2 millimeters and 3 millimeters.

[0075] The web of the filter material may have a uniform thickness.

[0076] One or both of the first lateral edge region and the second lateral edge region may have a smaller thickness than the main region.

[0077] One of the first lateral edge region and the second lateral edge region may have a smaller thickness than the main region, and the other one of the first lateral edge region and the second lateral edge region may have a same thickness as the main region.

[0078] A thickness of the first lateral edge region may be the same as a thickness of the second lateral edge region.

[0079] A thickness of the first lateral edge region may be different from a thickness of the second lateral edge region.

[0080] The first lateral edge region may be recessed with respect to the main region. The recess of the first lateral edge region may face towards the rod of filter material upon wrapping and / or after wrapping. The second lateral edge region may be recessed with respect to the main region. The recess of the second lateral edge region may face away from the rod of the filter material upon wrapping and / or after wrapping.

[0081] One or both of the first lateral edge region and the second lateral edge region may be free of at least one of the at least two wrapper layers.

[0082] The first lateral edge region may be free of at least one first wrapper layer of the at least two wrapper layers. The at least one first wrapper layer may form part of the main region. That at least one first wrapper layer may form part of the second lateral edge region. The at least one first wrapper layer may form at least one innermost wrapper layer after the wrapping step.

[0083] The second lateral edge region may be free of at least one second wrapper layer of the at least two wrapper layers. The at least one wrapper layer may form part of the main region. That at least one second wrapper layer may form part of the first lateral edge region. The at least one second wrapper layer may form at least one outermost wrapper layer after the wrapping step.

[0084] A combined thickness of the first lateral edge region and the second lateral edge region may be less than 150 percent of a thickness of the main region. A combined thickness of the first lateral edge region and the second lateral edge region may correspond to a thickness of the main region.

[0085] An adhesive layer may be applied to a surface of the web of filter wrapper. The adhesive layer may come in contact with the rod of filter material upon the wrapping step. The surface of the web of filter wrapper to which the adhesive is applied may form an inner surface of the wrapper tube after wrapping.

[0086] The filter segment may be combined with at least one additional segment by wrapping a tipping paper at least partially around each of the filter segment and the additional segment.

[0087] The web of filter wrapper may comprise biodegradable material or consist of biodegradable material. The web of filter wrapper may comprise one or more of paper, cardboard, carton, airlaid, and nonwoven.

[0088] The rod of filter material may be made from biodegradable material.

[0089] The rod of filter material may comprise one or both of cellulose and paper. The cellulose may be regenerated cellulose. The rod of filter material may consist of paper. The rod of filter material may comprise a tow comprising regenerated cellulose filaments, or paper, or regenerated cellulose, for example. The rod of filter material may comprise a paper-like web comprising cellulose. The rod of filter material may comprise a web or sheet material, in particular a crimped web or sheet material. The rod of filter material may comprise or consist of paper or non-woven material made with cellulose and / or a mix of cellulose with regenerated cellulose.

[0090] The rod of filter material may be free of cellulose acetate.

[0091] The rod of filter material may comprise a cellulosic filtration material or consist of a cellulosic filtration material. The cellulosic filtration material may be free of cellulose acetate. The cellulosic filtration material may comprise a paper material. The cellulosic filtration material may comprise a nonwoven paper material. The cellulosic filtration material may comprise a fibrous material comprising a plurality of regenerated cellulose fibres. The regenerated cellulose fibres may be one or more of viscose fibres, modal fibres, Lyocell fibres and viscose rayon fibres. The cellulosic filtration material may comprise a fibrous material comprising a plurality of natural fibres. The natural fibres may be one or more of flax fibres, hemp fibres, jute fibres, kenaf fibres, ramie fibres, abaca fibres, phormium fibres, sisal fibres, coir fibres, cotton fibres, and kapok fibres.

[0092] According to another aspect of the present invention, there is provided a use of a filter wrapper. The filter wrapper has at least a portion with a grammage of at least 120 grams per square meter. The filter wrapper is used to wrap around a rod of filter material to create a filter segment with increased hardness.

[0093] If the filter wrapper or the web of filter wrapper has at least two wrapper layers, all or at least two of the at least two wrapper layers may have the same thickness. The at least two wrapper layers may comprise wrapper layers having different thicknesses.

[0094] The at least two wrapper layers may comprise a wrapper layer having a grammage between 35 grams per square meter and 200 grams per square meter, or between 35 grams per square meter and 180 grams per square meter, or between 35 grams per square meter and 160 grams per square meter, or between 50 grams per square meter and 160 grams per square meter, or between 80 grams per square meter and 160 grams per square meter.

[0095] All wrapper layers of the at least two wrapper layers may have a grammage between 35 grams per square meter and 200 grams per square meter, or between 35 grams per square meter and 180 grams per square meter, or between 35 grams per square meter and 160 grams per square meter, or between 50 grams per square meter and 160 grams per square meter, or between 80 grams per square meter and 160 grams per square meter.

[0096] The at least two wrapper layers may comprise at least three wrapper layers.

[0097] The portion of the filter wrapper or the web of filter wrapper having the grammage of at least 120 grams per square meter may comprise at least 60 percent, or at least 70 percent, or at least 80 percent, or at least 90 percent of a total area of the filter wrapper or of the web of filter wrapper. The portion of the filter wrapper or of the web of filter wrapper may be a coherent portion of the filter wrapper or of the web of filter wrapper. The portion of the filter wrapper may comprise a totality of the area of the filter wrapper, where the filter wrapper does not overlap on itself due to being wrapped around the plug of filter material.

[0098] The filter wrapper and the web of filter wrapper are sheet-like and have a length dimension, a width dimension (or lateral direction), and a thickness dimension, respectively. The thickness dimension is the smallest dimension.

[0099] The feature that at least a portion of a filter wrapper (or of a web of filter wrapper) has a certain grammage is to be interpreted to mean that at least a certain area of the filter wrapper (or of the web of filter wrapper) defined in a length-width plane of the filter wrapper (or of the web of filter wrapper) has the indicated grammage. The indication “a portion” is, however, not intended to mean that the filter wrapper (or the web of filter wrapper) may be (virtually or physically) separated into layers stacked above each other in the thickness direction to define the “portion”. The entire thickness of the filter wrapper (or of the web of filter wrapper) has to be considered, when assessing whether a portion of the filter wrapper (or of the web of filter wrapper) has a certain grammage.

[0100] If the filter wrapper or the web of filter wrapper comprises more than one wrapper layer stacked above each other, the grammage of a portion of the filter wrapper or the web of filter wrapper is the combined grammage of the wrapper layers stacked above each other in the portion, including further components provided between the layers such as adhesive in the case of a laminate, if applicable.

[0101] The circumferential direction extends around the axial direction. The radial direction is perpendicular to the axial direction.

[0102] Features, descriptions and advantages presented in the context of any one of the aspects, embodiments, or examples described herein may be combined with or transferred to any of the other aspects, embodiments, or examples described herein. The methods and the use described herein may be suitable, adapted, or configured to produce the filter segments or the aerosolgenerating article described herein. The filter segments or the aerosol-generating article described herein may be manufactured with the methods or the use described herein. The methods described herein may comprise or involve the use described herein.

[0103] The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0104] Example Ex1 : Filter segment for an aerosol-generating article, comprising: a plug of filter material extending along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material; and a filter wrapper; wherein the filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material; wherein the wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube; wherein an axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube, and an axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube; and wherein at least a portion of the filter wrapper has a grammage of at least 120 grams per square meter. Example Ex2: Filter segment according to Example Ex1 , wherein the portion of the filter wrapper has a grammage of at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0105] Example Ex3: Filter segment according to Example Ex1 or Ex2, wherein the filter wrapper comprises a single wrapper layer.

[0106] Example Ex4: Filter segment according to Example Ex1 or Ex2, wherein the filter wrapper comprises at least two wrapper layers provided radially above each other, in particular a laminate of at least two wrapper layers provided radially above each other.

[0107] Example Ex5: Filter segment for an aerosol-generating article, comprising: a plug of filter material extending along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material; and a filter wrapper; wherein the filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material; wherein the wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube; wherein an axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube, and an axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube; and wherein the filter wrapper comprises at least two wrapper layers provided radially above each other, in particular a laminate of at least two wrapper layers provided radially above each other.

[0108] Example Ex6: Filter segment according to any one of Examples Ex1 to Ex5, wherein a width of an overlap of the filter wrapper along the circumferential direction is between 1 millimeter and 5 millimeters, or between 2 millimeters and 4 millimeters, or between 2 millimeters and 3 millimeters.

[0109] Example Ex7: Filter segment according to any one of Examples Ex1 to Ex6, wherein the filter wrapper has a uniform thickness.

[0110] Example Ex8: Filter segment according to any one of Examples Ex1 to Ex7, wherein the filter wrapper has a first edge region, a second edge region, and a main region provided between the first edge region and the second edge region, and wherein the first edge region overlaps the second edge region to close the wrapper tube.

[0111] Example Ex9: Filter segment according to Example Ex8, wherein the first edge region and the second edge region are fixed to each other by an adhesive. Example Ex10: Filter segment according to Example Ex8 or Ex9, wherein one or both of the first edge region and the second edge region have a smaller thickness than the main region.

[0112] Example Ex1 1 : Filter segment according to any one of Examples Ex8 to Ex10, wherein one of the first edge region and the second edge region has a smaller thickness than the main region, and the other one of the first edge region and the second edge region has a same thickness as the main region.

[0113] Example Ex12: Filter segment according to any one of Examples Ex8 to Ex10, wherein a thickness of the first edge region is the same as a thickness of the second edge region.

[0114] Example Ex13: Filter segment according to any one of Examples Ex8 to Ex11 , wherein a thickness of the first edge region is different from a thickness of the second edge region.

[0115] Example Ex14: Filter segment according to any one of Examples Ex8 to Ex13, wherein the first edge region is recessed with respect to the main region, wherein the recess of the first edge region preferably faces towards an inside of the filter segment.

[0116] Example Ex15: Filter segment according to any one of Examples Ex8 to Ex14, wherein the second edge region is recessed with respect to the main region, wherein the recess of the second edge region preferably faces towards an outside of the filter segment.

[0117] Example Ex16: Filter segment according to any one of Examples Ex8 to Ex15, wherein a combined thickness of the first edge region and the second edge region is less than 150 percent of the thickness of the main region.

[0118] Example Ex17: Filter segment according to any one of Examples Ex8 to Ex16, wherein a combined thickness of the first edge region and the second edge region corresponds to the thickness of the main region.

[0119] Example Ex18: Filter segment according to any one of Examples Ex8 to Ex17, wherein one or both of the first edge region and the second edge region are free of at least one of the at least two wrapper layers of the filter wrapper.

[0120] Example Ex19: Filter segment according to any one of Examples Ex8 to Ex18, wherein the first edge region is free of at least one first wrapper layer of the at least two wrapper layers of the filter wrapper.

[0121] Example Ex20: Filter segment according to Example Ex19, wherein the at least one first wrapper layer forms part of the main region.

[0122] Example Ex21 : Filter segment according to Example Ex19 or Ex20, wherein the at least one first wrapper layer forms part of the second edge region.

[0123] Example Ex22: Filter segment according to any one of Examples Ex19 to Ex21 , wherein the at least one first wrapper layer is at least one innermost wrapper layer of the filter wrapper.

[0124] Example Ex23: Filter segment according to any one of Examples Ex8 to Ex22, wherein the second edge region is free of at least one second wrapper layer of the at least two wrapper layers of the filter wrapper. Example Ex24: Filter segment according to Example Ex23, wherein the at least one second wrapper layer forms part of the main region.

[0125] Example Ex25: Filter segment according to Example Ex23 or Ex24, wherein the at least one second wrapper layer forms part of the first edge region.

[0126] Example Ex26: Filter segment according to any one of Examples Ex23 to Ex25, wherein the at least one second wrapper layer is at least one outermost wrapper layer of the filter wrapper.

[0127] Example Ex27: Filter segment according to any one of Examples Ex1 to Ex26, wherein the plug of filter material is in contact with an inner surface of the wrapper tube.

[0128] Example Ex28: Filter segment according to any one of Examples Ex1 to Ex27, wherein an adhesive layer is provided on an inner surface of the wrapper tube.

[0129] Example Ex29: Filter segment according to any one of Examples Ex1 to Ex28, wherein the filter wrapper comprises one or more of paper, cardboard, carton, airlaid, and nonwoven.

[0130] Example Ex30: Filter segment according to any one of Examples Ex1 to Ex29, wherein the plug of filter material is made from biodegradable material.

[0131] Example Ex31 : Filter segment according to any one of Examples Ex1 to Ex30, wherein the plug of filter material comprises one or both of cellulose, in particular regenerated cellulose, and paper.

[0132] Example Ex32: Filter segment according to any one of Examples Ex1 to Ex31 , wherein the plug of filter material is free of cellulose acetate.

[0133] Example Ex33: Filter segment according to any one of Examples Ex1 to Ex32, wherein a hardness of the plug of filter material is below 20 percent, and wherein a hardness of the filter segment is at least 85 percent.

[0134] Example Ex34: Aerosol-generating article, comprising: a filter segment according to any one of Examples Ex1 to Ex33; one or more additional segments, wherein the one or more additional segments comprises an aerosol-generating segment with an aerosol-generating substrate; and a tipping paper at least partially wrapped around the filter segment and at least partially wrapped around at least one of the one or more additional segments.

[0135] Example Ex35: Method for manufacturing filter segments, comprising: providing a rod of filter material; providing at least two wrapper layers; combining the at least two wrapper layers into a web of filter wrapper; and subsequently wrapping the web of filter wrapper around the rod of filter material.

[0136] Example Ex36: Method according to Example Ex35, further comprising cutting the wrapped rod of filter material into filter segments.

[0137] Example Ex37: Method according to Example Ex35 or Ex36, wherein at least a portion of the web of filter wrapper has a grammage of at least 120 grams per square meter, or at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0138] Example Ex38: Method according to any one of Examples Ex35 to Ex37, wherein combining the at least two wrapper layers into the web of filter wrapper comprises laminating the at least two wrapper layers to each other.

[0139] Example Ex39: Method according to any one of Examples Ex35 to Ex38, wherein the at least two wrapper layers comprise at least one wrapper layer having a first width and at least one wrapper layer having a second width.

[0140] Example Ex40: Method according to any one of Examples Ex35 to Ex38, wherein all wrapper layers of the at least two wrapper layers have a same width.

[0141] Example Ex41 : Method according to any one of Examples Ex35 to Ex40, wherein at least two of the wrapper layers are combined in an offset manner with respect to a width direction.

[0142] Example Ex42: Method for manufacturing filter segments, comprising: providing a rod of filter material; wrapping a web of filter wrapper around the rod of filter material such that the web of filter wrapper forms a wrapper tube around the rod of filter material, while the rod of filter material and the web of filter wrapper are conveyed along a production direction; and cutting the wrapped rod of filter material into filter segments; wherein at least a portion of the web of filter wrapper has a grammage of at least 120 grams per square meter.

[0143] Example Ex43: Method according to Example Ex42, wherein the portion of the web of filter wrapper has a grammage of at least 140 grams per square meter, or at least 160 grams per square meter, or at least 180 grams per square meter, or at least 200 grams per square meter, or at least 220 grams per square meter, or at least 240 grams per square meter, or at least 260 grams per square meter.

[0144] Example Ex44: Method according to Example Ex42 or Ex43, wherein the web of filter wrapper comprises a single wrapper layer.

[0145] Example Ex45: Method according to any one of Examples Ex42 or Ex43, wherein the web of filter wrapper comprises at least two wrapper layers provided radially above each other after forming of the wrapper tube.

[0146] Example Ex46: Method according to any one of Examples Ex42, Ex43 or Ex45, wherein the web of filter wrapper comprises a laminate of at least two wrapper layers.

[0147] Example Ex47: Method according to any one of Examples Ex35 to Ex46, wherein the web of filter wrapper has a first lateral edge region, a second lateral edge region, and a main region provided between the first lateral edge region and the second lateral edge region, and wherein wrapping the web of filter wrapper around the rod of filter material comprises overlapping the first lateral edge region over the second lateral edge region.

[0148] Example Ex48: Method according to Example Ex47, further comprising applying a pressure onto an overlap between the first lateral edge region and the second lateral edge region.

[0149] Example Ex49: Method according to Example Ex47 or Ex48, further comprising applying an adhesive to at least one of the first lateral edge region and the second lateral edge region before overlapping the first lateral edge region over the second lateral edge region.

[0150] Example Ex50: Method according to any one of Examples Ex47 to Ex49, wherein a width of an overlap between the first lateral edge region and the second lateral edge region along the circumferential direction is between 1 millimeter and 5 millimeters, or between 2 millimeters and 4 millimeters, or between 2 millimeters and 3 millimeters.

[0151] Example Ex51 : Method according to any one of Examples Ex47 to Ex50, wherein one or both of the first lateral edge region and the second lateral edge region have a smaller thickness than the main region.

[0152] Example Ex52: Method according to any one of Examples Ex47 to Ex51 , wherein one of the first lateral edge region and the second lateral edge region has a smaller thickness than the main region, and the other one of the first lateral edge region and the second lateral edge region has a same thickness as the main region.

[0153] Example Ex53: Method according to any one of Examples Ex47 to Ex51 , wherein a thickness of the first lateral edge region is the same as a thickness of the second lateral edge region.

[0154] Example Ex54: Method according to any one of Examples Ex47 to Ex52, wherein a thickness of the first lateral edge region is different from a thickness of the second lateral edge region.

[0155] Example Ex54: Method according to any one of Examples Ex47 to Ex53, wherein the first lateral edge region is recessed with respect to the main region, wherein the recess of the first lateral edge region preferably faces towards the rod of filter material upon wrapping.

[0156] Example Ex55: Method according to any one of Examples Ex47 to Ex54, wherein the second lateral edge region is recessed with respect to the main region, wherein the recess of the second lateral edge region preferably faces away from the rod of filter material upon wrapping.

[0157] Example Ex56: Method according to any one of Examples Ex47 to Ex55, wherein one or both of the first lateral edge region and the second lateral edge region are free of at least one of the at least two wrapper layers.

[0158] Example Ex56: Method according to any one of Examples Ex47 to Ex52, wherein the first lateral edge region is free of at least one first wrapper layer of the at least two wrapper layers.

[0159] Example Ex57: Method according to Example Ex56, wherein the at least one first wrapper layer forms part of the main region. Example Ex58: Method according to Example Ex56 or Ex57, wherein the at least one first wrapper layer forms part of the second lateral edge region.

[0160] Example Ex59: Method according to any one of Examples Ex56 to Ex58, wherein the at least one first wrapper layer forms at least one innermost wrapper layer after the wrapping step.

[0161] Example Ex60: Method according to any one of Examples Ex47 to Ex59, wherein the second lateral edge region is free of at least one second wrapper layer of the at least two wrapper layer.

[0162] Example Ex61 : Method according to Example Ex60, wherein the at least one second wrapper layer forms part of the main region.

[0163] Example Ex62: Method according to Example Ex60 or Ex61 , wherein the at least one second wrapper layer forms part of the first lateral edge region.

[0164] Example Ex63: Method according to any one of Examples Ex60 to Ex62, wherein the at least one second wrapper layer forms at least one outermost wrapper layer after the wrapping step.

[0165] Example Ex64: Method according to any one of Examples Ex47 to Ex63, wherein a combined thickness of the first lateral edge region and the second lateral edge region is less than 150 percent of a thickness of the main region.

[0166] Example Ex65: Method according to any one of Examples Ex47 to Ex64, wherein a combined thickness of the first lateral edge region and the second lateral edge region corresponds to a thickness of the main region.

[0167] Example Ex66: Method according to any one of Examples Ex35 to Ex50, wherein the web of filter wrapper has a uniform thickness.

[0168] Example Ex67: Method according to any one of Examples Ex35 to Ex66, further comprising applying an adhesive layer to a surface of the web of filter wrapper, wherein the adhesive layer comes in contact with the rod of filter material upon the wrapping step.

[0169] Example Ex68: Method according to any one of Examples Ex35 to Ex67, further comprising combining the filter segment with at least one additional segment by wrapping a tipping paper at least partially around each of the filter segment and the additional segment.

[0170] Example Ex69: Method according to any one of Examples Ex35 to Ex68, wherein the web of filter wrapper comprises one or more of paper, cardboard, carton, and airlaid.

[0171] Example Ex70: Method according to any one of Examples Ex35 to Ex69, wherein the rod of filter material is made from biodegradable material.

[0172] Example Ex71 : Method according to any one of Examples Ex35 to Ex70, wherein the rod of filter material comprises one or both of cellulose, in particular regenerated cellulose, and paper.

[0173] Example Ex72: Method according to any one of Examples Ex35 to Ex71 , wherein the rod of filter material is free of cellulose acetate. Example Ex73: Use of a filter wrapper having at least a portion with a grammage of at least 120 grams per square meter to wrap around a rod of filter material to create a filter segment with increased hardness.

[0174] Example Ex74: Use according to Example Ex73, wherein the filter wrapper is circumferentially wrapped around the rod of filter material such that the filter wrapper forms a wrapper tube around the rod of filter material.

[0175] Example Ex75: Use according to Example Ex74, wherein the filter wrapper has a first edge region, a second edge region, and a main region provided between the first edge region and the second edge region, and wherein the first edge region overlaps the second edge region to close the wrapper tube.

[0176] Example Ex76: Use according to Example Ex75, wherein one or both of the first edge region and the second edge region have a smaller thickness than the main region.

[0177] Examples will now be further described with reference to the figures in which:

[0178] Figure 1 shows a perspective illustration of manufacturing a filter segment according to an embodiment.

[0179] Figure 2 shows a schematic illustration of manufacturing a filter segment according to an embodiment having a filter wrapper comprising a single wrapper layer.

[0180] Figure 3 shows a schematic illustration of manufacturing a filter segment according to an embodiment having a filter wrapper comprising two wrapper layers.

[0181] Figure 4 shows a schematic illustration of manufacturing a filter segment according to an embodiment having a filter wrapper comprising three wrapper layers.

[0182] Figure 5 shows a schematic sectional view of the filter wrapper comprising three wrapper layers.

[0183] Figure 6 shows a schematic illustration of manufacturing a filter segment according to another embodiment having a filter wrapper comprising three wrapper layers.

[0184] Figure 7 shows a schematic illustration of an aerosol-generating article according to an embodiment.

[0185] Figure 8 shows a schematic illustration of a way of measuring a hardness.

[0186] Figure 1 illustrates a process of manufacturing filter segments 1 according to an embodiment. Sheet-like filter material 3 is conveyed through a funnel-shaped converging device 5 to form a continuous rod 7 of filter material 3. The sheet of filter material 3 may, for example, comprise cellulose, in particular regenerated cellulose, or paper.

[0187] The rod 7 of filter material 3 is conveyed along a production direction 9. Downstream of the funnel-shaped converging device 5, the rod 7 of filter material 3 is set on a web of filter wrapper 11 supplied from a bobbin 13. The rod 7 of filter material 3 and the web of filter wrapper 1 1 are provided to a wrapping station 15. The wrapping station 15 comprises an endless conveyor with a flexible conveyor belt, a so-called garniture tape 17 driven in an endless loop by a driven roller 19. The web of filter wrapper 11 with the continuous rod 7 of filter material 3 on it is pulled into the wrapping station 15 by the garniture tape 17. In the wrapping station 15, and the web of filter wrapper 1 1 is wrapped around the rod 7 of filter material 3. The wrapping comprises folding the continuous web of filter wrapper 11 around the continuous rod 7 of filter material 3 from both lateral sides. Downstream of the wrapping station 15, a cutting station 21 is provided to cut the wrapped rod 10 of filter material into individual filter segments 1 .

[0188] The web of filter wrapper 11 provided on the bobbin 13 may either comprise only a single wrapper layer or may be a pre-manufactured combination of multiple wrapper layers stacked above each other, in particular a laminate of multiple wrapper layers. Preferably, at least a portion of the filter wrapper has a grammage of at least 120 grams per square meter.

[0189] Figure 2 illustrates the process happening in the wrapping station 15 according to an embodiment with the web of filter wrapper 1 1 comprising only a single wrapper layer 23. In the wrapping station 15, the web of filter wrapper 1 1 is progressively closed around the continuous rod 7 of filter material 3, such that, in the end, a first lateral edge region 25 of filter wrapper 1 1 overlaps a second lateral edge region 27 of the filter wrapper 11 .

[0190] When the filter wrapper 1 1 is partly bent around the continuous rod 7 of filter material 3, a glue line 29 is applied to an inner surface of the first lateral edge region 25 of the web of filter wrapper 1 1 by an applicator 31. Alternatively, the glue line 29 may be applied to an outer surface of the second lateral edge region 27 by the applicator 31. The glue line 29 extends along the production direction 9, or along the extension direction of the continuous rod 7 of filter material 3.

[0191] After the glue line 29 has been applied, the web of filter wrapper 11 is fully wrapped around the continuous rod 7 of filter material 3 so that the first lateral edge region 25 overlaps the second lateral edge region 27. The glue line 29 comes in contact with the outer surface of the second lateral edge region 27, such that the glue line 29 attaches the first lateral edge region 25 and the second lateral edge region 27 to each other.

[0192] The wrapped rod 10 has a bulge 33 due to the first lateral edge region 25 of the filter wrapper 11 overlapping the second lateral edge region 27 of the filter wrapper 1 1 . A heater bar 35 is lowered onto the bulge 33 to exert a pressure onto the overlap between the first lateral edge region 25 and the second lateral edge region 27, thereby compressing the bulge 33 and reducing the deviation of a cylindrical shape of the wrapped rod 10 caused by the bulge 33. The heater bar 35 may also contribute to drying or solidify the glue line 29.

[0193] Figure 3 shows an embodiment in which the web of filter wrapper 11 comprises two wrapper layers, a first wrapper layer 23 and a second wrapper layer 37. In the illustrated embodiment, the first wrapper layer 23 is supplied by a first bobbin 39 and the second wrapper layer 37 is supplied by a second bobbin 41 . An application roller 43 covers one side of the first wrapper layer 23 in an adhesive. The second wrapper layer 37 is brought into surface contact with the side of the first wrapper layer 23 covered with the adhesive 45. Then, the first wrapper layer 23 and the second wrapper layer 37 are provided to laminating rollers 47 forming the filter wrapper 11 by laminating together the first wrapper layer 23 and the second wrapper layer 37 using the adhesive 45. The filter wrapper 1 1 created by this lamination process is then supplied to the wrapping station 15. Alternatively, the laminate of the first wrapper layer 23 and the second wrapper layer 37 could be manufactured beforehand and be provided to the wrapping station 15 from a single bobbin. According to a further alternative, the adhesive 45 could be omitted and the filter wrapper 1 1 could be provided as a superposition or stack of the first wrapper layer 23 and the second wrapper layer 37, instead of as a laminate.

[0194] A width of the first wrapper layer 23 is smaller than a width of the second wrapper layer 37. At the lateral end of the web of filter wrapper 1 1 forming the second lateral edge region 27, the first wrapper layer 23 and the second wrapper layer 37 are flush with each other. At the opposing lateral end of the web of filter wrapper 11 , the second wrapper layer 37 laterally extends beyond the first wrapper layer 23, such that the first lateral edge region 25 is formed by the second wrapper layer 37 alone, but is free of the first wrapper layer 23. This leads to the first lateral edge region 25 being recessed with respect to a main region 49 of the filter wrapper 1 1 being provided laterally between the first lateral edge region 25 and the second lateral edge region 27. The second lateral edge region 27, by contrast, is not recessed with respect to the main region 49, but has the same thickness as the main region 49 and essentially is an extension of the main region 49.

[0195] Since, in the embodiment of figure 3, the first lateral edge region 25 is formed only by the second wrapper layer 37, the overlap between the first lateral edge region 25 and the second lateral edge region 27 has a reduced thickness compared to an embodiment in which the entirety of the web of filter wrapper 1 1 would be formed by the first wrapper layer 23 and the second wrapper layer 37 stacked on each other. This results in a smaller bulge 33 and use of the heat bar 35 may be omitted in the embodiment of figure 3. However, the heat bar 35 could still be applied in the same manner as shown in figure 2.

[0196] Figure 4 shows an embodiment in which the filter wrapper 1 1 is a laminate of three wrapper layers, a first wrapper layer 23, a second wrapper layer 37, and a third wrapper layer 51 . The production line essentially corresponds to the production line shown in figure 3, but with an additional bobbin 53 providing the third wrapper layer 51 and an additional applicator roll 55 applying an additional layer of adhesive 45 between the first wrapper layer 23 and the third wrapper layer 51 for lamination. The lamination rolls 47 laminate the three wrapper layers 23, 37, 51 to each other to create the web of filter wrapper 1 1. Again, the laminate could instead be manufactured beforehand and be provided to the wrapping station 15 from a single bobbin. The adhesive 45 could be omitted and the filter wrapper 11 could be provided as a superposition or stack of the first wrapper layer 23, the second wrapper layer 37, and the third wrapper layer 51 instead of as a laminate. As shown in figure 4, the third filter wrapper 51 has the same dimensions as the first filter wrapper 23. The first lateral edge region 25 of the filter wrapper 1 1 is formed only by the second filter wrapper 37, but is free of the first filter wrapper 23 and the third filter wrapper 51 . The main region 49 and the second lateral edge region 27 of the web of filter wrapper 11 , by contrast, are formed by all three wrapper layers 37, 23, 51 laminated onto each other.

[0197] In the embodiment of figure 4, the first wrapper layer 23 and the third wrapper layer 51 have the same width and lie exactly on top of each other. Considering the finite thickness of the first wrapper layer 23 and the third wrapper layer 51 , this would lead to a gap between opposing lateral ends of at least the first wrapper layer 23, if the third wrapper layer 51 was dimensioned to have the opposing lateral ends of the third wrapper layer 51 abut each other after wrapping. Figure 5 illustrates how to account for this, if one wants to have both the opposing lateral ends of the first wrapper layer 23 and the opposing lateral ends of the third wrapper layer 51 abut each other after wrapping. According to Figure 5, the width of the first wrapper layer 23 is made greater than the width of the third wrapper layer 51 considering the heights of the individual wrapper layers 23, 37, 51 . Considering that the second wrapper layer 37 has a finite width as well, the first lateral edge region 25 overlapping the second lateral edge region 27 is not formed by the entire part of the second wrapper layer 37 laterally extending beyond the first wrapper layer 23, but only by a part thereof.

[0198] Figure 6 shows another embodiment with a filter wrapper 11 comprising a laminate of three wrapper layers, a first wrapper layer 23, a second wrapper layer 37, and a third wrapper layer 51 . In the embodiment of Figure 6, too, lamination may be omitted and a stack of wrapper layers may be used. In the embodiment of Figure 6, both the first lateral edge region 25 (the overlapping edge region) and the second lateral edge region 27 (the overlapped edge region) of the filter wrapper 11 are recessed with respect to the main region 49. The first lateral edge region 25 is formed only by the second wrapper layer 37, but is free of the first wrapper layer 23 and the third wrapper layer 51 . The second lateral edge region 27 is formed by the first wrapper layer 23 and the third wrapper layer 51 , but is free of the second wrapper layer 37. This means that the first lateral edge region 25 is recessed with respect to the main region 49 such that the recess faces towards the rod 7 of filter material 3 upon wrapping or after wrapping. The recess at the second lateral edge region 27, by contrast, faces away from the rod 7 of filter material 3 upon wrapping or after wrapping. Taking heed of the considerations explained with respect to figure 5, the wrapping layers 23, 37, 51 in the embodiment of figure 6 may be dimensioned such that all three wrapper layers 23, 37, 51 have their opposing lateral ends face to face or abutting each other in the wrapped configuration. Due to the recesses formed in the first lateral edge region 25 and the second lateral edge region 27 facing into opposing directions, formation of a bulge 33 upon wrapping may be avoided.

[0199] After the wrapped rod 10 of filter material according to any of the embodiments has been cut into segments 1 , the segments 1 may be used to manufacture an aerosol-generating article 59. Figure 7 schematically shows assembly of such aerosol-generating article 59. The aerosolgenerating article 59 comprises the filter segment 1 and at least one additional segment.

[0200] The filter segment 1 comprises a plug 90 of filter material 3 separated from the continuous rod 7 of filter material 3, when the wrapped rod 10 of filter material is cut in the cutting station 21 . The plug 90 of filter material 3 extends along an axial direction 91 from a first end 93 of the plug 90 of filter material 3 to a second end 95 of the plug 90 of filter material 3. Further, the filter segment 1 comprises a wrapper tube 97 formed by the filter wrapper 11 and extending around the filter material 3 along a circumferential direction 99. The wrapper tube 97 extends along the axial direction 91 from a first end 101 of the wrapper tube 97 to a second end 103 of the wrapper tube 97. An axial position of the first end 93 of the plug 90 of filter material 3 corresponds to an axial position of the first end 101 of the wrapper tube 97, and an axial position of the second end 95 of the plug 90 of filter material 3 corresponds to an axial position of the second end 103 of the wrapper tube 97.

[0201] In the illustrated embodiment, the additional segments comprise a cooling and spacing segment 61 , an aerosol-generating segment 63 and a front plug segment 65. The additional segments 61 , 63, 65 are combined using a cigarette paper 67 wrapped around all of the additional segments 61 , 63, 65. The combination of the additional segment 61 , 63, 65 held together by the cigarette paper 67 is then combined with the filter segment 1 by wrapping a tipping paper 69 at least partially around the filter segment 1 and the combined assembly of additional segments 61 , 63, 65, in particular at least partly around the cooling and spacing segment 61 .

[0202] Figure 8 illustrates a method for measuring a hardness of a rod-shaped specimen 80, such as a filter segment 1 or a plug 90 of filter material. The term “hardness” used throughout this specification denotes the resistance to deform. Hardness is generally expressed as a percentage. The left part of Figure 8 shows a specimen 80 before applying a load 81 and the same specimen 80 whilst applying the load 81 . Before the load 81 has been applied, the specimen 80 has a diameter D1 (reference numeral 83). The specimen 80 after applying a set load for a set duration (but with the load still applied) has a (reduced) diameter D2 (reference numeral 85). The depression is d=D1 -D2. Referring to FIG. 8, hardness is given by the formula: hardness [%] = D2 / D1 *100%. The harder the material, the closer the hardness is to 100 percent.

[0203] As generally known in the art, to determine the hardness of a rod-like specimen 80, such as a filter segment 1 or a plug 90 of filter material, the specimen 80 should be subjected to a set load for a set duration. This test is performed using a known DD60A Densimeter device (manufactured and made commercially available by Heinr. Borgwaldt GmbH, Germany), which is fitted with a measuring head for cigarettes and with a cigarette receptacle, as schematically shown in the right part of Figure 8.

[0204] The load is applied using two load applying cylindrical rods 85, which extend across the diameter of a group of identical specimens 80 at once. According to the standard test method for this instrument, the test should be performed such that twenty contact points occur between the specimens 80 and the load applying cylindrical rods 85. In some cases, the specimens 80 to be tested may be long enough such that only ten specimens 80 are needed to form twenty contact points, with each specimen 80 contacting both load applying rods 85 (because they are long enough to extend between the rods 85). In other cases, if the specimens 80 are too short to achieve this, then twenty specimens 80 should be used to form the twenty contact points, with each specimen 80 contacting only one of the load applying rods 86.

[0205] Two further stationary cylindrical rods 87 are located underneath the specimens 80, to support the specimens 80 and counteract the load applied by each of the load applying cylindrical rods 85.

[0206] For the standard operating procedure for such an apparatus, an overall load of 2 kg is applied for a duration of 20 seconds. After 20 seconds have elapsed (and with the load still being applied to the specimens 80), the depression in the load applying cylindrical rods 85 is determined, and then used to calculate the hardness from the equation hardness [%] = D2 / D1 *100% explained above. The temperature is kept in the region of 22 degrees Centigrade ± 2 degrees. The test described above is referred to as the DD60A Test.

Claims

Claims1 . Filter segment for an aerosol-generating article, comprising: a plug of filter material extending along an axial direction from a first end of the plug of filter material to a second end of the plug of filter material; and a filter wrapper; wherein the filter wrapper is circumferentially wrapped around the plug of filter material such that the filter wrapper forms a wrapper tube around the plug of filter material; wherein the wrapper tube extends along the axial direction from a first end of the wrapper tube to a second end of the wrapper tube; wherein an axial position of the first end of the plug of filter material corresponds to an axial position of the first end of the wrapper tube, and an axial position of the second end of the plug of filter material corresponds to an axial position of the second end of the wrapper tube; wherein at least a portion of the filter wrapper has a grammage of at least 120 grams per square meter; wherein the filter wrapper has a first edge region, a second edge region, and a main region provided between the first edge region and the second edge region, and wherein the first edge region overlaps the second edge region to close the wrapper tube; and wherein one or both of the first edge region and the second edge region have a smaller thickness than the main region.

2. Filter segment according to claim 1 , wherein the filter wrapper comprises at least two wrapper layers provided radially above each other, in particular a laminate of at least two wrapper layers provided radially above each other.

3. Filter segment according to claim 2, wherein one or both of the first edge region and the second edge region are free of at least one of the at least two wrapper layers of the filter wrapper.

4. Filter segment according to any one of the preceding claims, wherein a thickness of the first edge region is different from a thickness of the second edge region.

5. Filter segment according to any one of the preceding claims, wherein the first edge region is recessed with respect to the main region, wherein the recess of the first edge region preferably faces towards an inside of the filter segment.

6. Filter segment according to any one of the preceding claims, wherein a combined thickness of the first edge region and the second edge region is less than 150 percent of the thickness of the main region.

7. Filter segment according to any one of the preceding claims, wherein the filter wrapper comprises one or more of paper, cardboard, carton, airlaid, and nonwoven.

8. Filter segment according to any one of the preceding claims, wherein the plug of filter material is made from biodegradable material.

9. Filter segment according to any one of the preceding claims, wherein the plug of filter material comprises one or both of cellulose, in particular regenerated cellulose, and paper.

10. Filter segment according to any one of the preceding claims, wherein a hardness of the plug of filter material is below 20 percent, and wherein a hardness of the filter segment is at least 85 percent.1 1 . Aerosol-generating article, comprising: a filter segment according to any one of the preceding claims; one or more additional segments, wherein the one or more additional segments comprises an aerosol-generating segment with an aerosol-generating substrate; and a tipping paper at least partially wrapped around the filter segment and at least partially wrapped around at least one of the one or more additional segments.

12. Method for manufacturing filter segments, comprising: providing a rod of filter material; providing at least two wrapper layers; combining the at least two wrapper layers into a web of filter wrapper; and subsequently wrapping the web of filter wrapper around the rod of filter material.

13. Method according to claim 12, wherein the web of filter wrapper has a first lateral edge region, a second lateral edge region, and a main region provided between the first lateral edge region and the second lateral edge region, and wherein wrapping the web of filter wrapper around the rod of filter material comprises overlapping the first lateral edge region over the second lateral edge region, the method further comprising applying a pressure onto an overlap between the first lateral edge region and the second lateral edge region.

14. Method according to claim 12, wherein the web of filter wrapper has a first lateral edge region, a second lateral edge region, and a main region provided between the first lateral edge region and the second lateral edge region, and wherein wrapping the web of filter wrapper around the rod of filter material comprises overlapping the first lateral edge region over the second lateral edge region, and wherein one or both of the first lateral edge region and the second lateral edge region have a smaller thickness than the main region.

15. Use of a filter wrapper having at least a portion with a grammage of at least 120 grams per square meter to wrap around a rod of filter material to create a filter segment with increased hardness, wherein the filter wrapper is circumferentially wrapped around the rod of filter material such that the filter wrapper forms a wrapper tube around the rod of filter material, wherein the filter wrapper has a first edge region, a second edge region, and a main region provided between the first edge region and the second edge region, and wherein the first edge region overlaps the second edge region to close the wrapper tube, and wherein one or both of the first edge region and the second edge region have a smaller thickness than the main region.

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