Assembly system for a filter

Abstract

An assembly system for a filter for a tobacco stick is disclosed. The assembly system comprises: a web of filter material comprising natural fibres; a garniture tongue arranged to receive the web of filter material and configured to shape the web of filter material into a filter rod for a tobacco stick; and a first heater configured to heat at least a portion of the garniture tongue.

Description

[0001] ASSEMBLY SYSTEM FOR A FILTER

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an assembly system for a filter for a tobacco stick, such as a cigarette or heat-not-burn article. In particular, the assembly system comprises a garniture tongue arranged for shaping a web of filter material comprising natural fibres into a filter rod for a tobacco stick. The invention also relates to a method of producing a filter for a tobacco stick using a garniture tongue.

[0004] BACKGROUND

[0005] Smoking articles, such as cigarettes, and heat-not-burn tobacco sticks include filters for filtering compounds from the aerosols inhaled by a consumer.

[0006] In the manufacturing of conventional filters, a component known as a garniture tongue is typically involved in shaping and guiding the filter material as it is formed into a filter rod. The garniture tongue ensures that the filter material is evenly distributed and compacted, leading to consistent filter quality.

[0007] Filters known in the art are usually made from cellulose acetate. However, when smoking articles are improperly thrown away, they often end up in the environment. Therefore, to decrease the environmental impact, filters comprising natural materials are becoming a more sought-after aim for manufacturers.

[0008] However, the shaping of new natural filter materials using conventional garniture tongues has been found to be associated with machine runability issues, as more frequent cleaning of the assembly system is typically required. It has also been found that the resulting filter rods often include high numbers of quality defects.

[0009] An object of the present invention is to address one or more of these issues. SUMMARY OF INVENTION

[0010] According to a first aspect of the invention, there is provided an assembly system for a filter for a tobacco stick, comprising: a web of filter material comprising natural fibres; a garniture tongue arranged to receive the web of filter material and configured to shape the web of filter material into a filter rod for a tobacco stick; and a first heater configured to heat at least a portion of the garniture tongue.

[0011] In this way, applying heat to at least a portion of the garniture tongue reduces the occurrence of quality defects in the produced filter rod and avoids machine runability issues. In particular, it has been found that the manufacturing of filters using filter material comprising natural fibres is associated with a rapid accumulation of residuals from the filter material on the internal surface of the garniture tongue. The residuals are produced as a result of the friction and pressure between the filter material and the garniture tongue. The accumulated residuals harden and build-up, thereby impeding the passage of further filter material through the garniture tongue by reducing the available cross-section, and leading to quality defects in the produced filter rod due to the presence of the accumulated residuals that provides undesired grooves / indentations on the external surfaces of the filter rod. This requires the manufacturing process to be stopped and the garniture tongue to be cleaned after only short periods of machine operation, e.g. a few minutes. By heating the garniture tongue using the first heater, this results in the accumulated residuals being softened and / or melted, such that the movement of filter material through the garniture tongue is not impeded and the filter material wipes and cleans the accumulated residuals from the surface of the garniture tongue. Hence, the occurrence of quality defects in the produced filter rod is reduced and the requirement to regularly stop the machine and clean the garniture tongue is avoided. For example, by using the garniture tongue according to the invention the machine can run for a full production cycle (e.g. for about 8 hours or more) without the requirement to stop the machine and clean the garniture tongue. The quality and production efficiency of the filter is therefore significantly improved. It will be understood that the expression “garniture tongue” refers to a tapered or funnelled portion of a garniture device. That is, the garniture tongue defines a region of the garniture device and is configured such that its cross-sectional area narrows in the downstream direction to progressively reduce the cross-sectional area of the received web of filter material. In other words, the garniture tongue is a portion of the garniture device providing a reduction of the cross-sectional area of the filter material to the desired cross-sectional area. Downstream of the garniture tongue the filter material will be fed into subsequent elements of the assembly system, for example into a channel defining a substantially constant cross-sectional passage that is arranged downstream of the garniture tongue.

[0012] In one example, the tobacco stick is a cigarette. In another example, the tobacco stick is a heat not-burn article.

[0013] It will be understood that the web of filter material does not comprise cellulose acetate.

[0014] Preferably, the natural fibres may be selected from one or more of wood fibres, cotton fibres, leaf fibres, such as abaca or sisal fibres, bast fibres, such as jute, hemp, flax or kenaf fibres, and / or regenerated cellulose such as viscose and / or lyocell fibres.

[0015] In some embodiments, the natural fibres comprise or consist of cellulose pulp, most preferably wood pulp, the cellulose pulp, most preferably wood pulp preferably being obtained by a kraft process.

[0016] In a preferred embodiment, the natural fibres comprise or consist of wood pulp, the wood pulp preferably being obtained by the kraft process.

[0017] Preferably, the web of filter material further comprises a binder. It has been found that the residuals which accumulate on the garniture tongue are often primarily composed of binder material.

[0018] In some embodiments, the binder comprises at least one binding agent being a water-based polymer emulsion. Preferably, the binder comprises one or more of: an aqueous copolymer dispersion of ethylene vinyl acetate, EVA, and polyvinyl acetate, PVAc; a cellulose derivative, preferably ethyl / methyl cellulose, hydroxyethylAmethyl cellulose and / or carboxymethyl cellulose; and a polysaccharide or a derivative of a polysaccharide, preferably dextrin and / or starch. These binders are particularly susceptible to accumulation, and applying heat particularly in the temperature ranges indicated below has been found to reliably facilitate their removal.

[0019] In some embodiments, the binder comprises a combination of ethylene vinyl acetate, EVA, and polyvinyl acetate, PVAc, wherein the weight ratio of EVA to PVAc is preferably between 70:30 and 30:70, more preferably between 60:40 and 40:60 and even more preferably between 55:45 and 45:55.

[0020] Preferably, the web of filter material comprises a non-woven substrate comprising (or consisting of) the natural fibres and the binder.

[0021] Preferably, the weight content of natural fibres is comprised between 85% and 95%, preferably between 86.9% and 95%, more preferably between 90% and 93%, and the weight content of the binder is comprised between 5% and 15%, preferably between 5% and 13.1 %, more preferably between 7% and 10%.

[0022] Preferably, the non-woven substrate is obtained by short fibre airlaid technology.

[0023] According to some embodiments, the average length of the natural fibres is at most 3.5 mm, preferably at most 3.0 mm and most preferably at most 2.8 mm, and / or the average length of the natural fibres is at least 2.0 mm, preferably at least 2.3 mm and most preferably at least 2.5 mm.

[0024] Preferably, the web of filter material has a thickness between 0.3 mm and 1 .3 mm.

[0025] Preferably, the web of filter material has basis weight of at least at least 35 g / m2, preferably between 40 g / m2and 60g / m2.

[0026] Preferably, the web of filter material has a width comprised between 50 mm and 240 mm or 100 to 220 mm, preferably 70 to 170 or 120 to 180 mm. In some embodiments, the width of the web of filter material is less than 160 mm, preferably comprised between 100 mm and 150 mm.

[0027] Preferably, the web of filter material has a volume density of at least 50 mg / cm3, preferably of at least 55 mg / cm3and most preferably above 60 mg / cm3, or at least 62 mg / cm3, and / or a volume density of at most 110 mg / cm3, preferably of at most 100 mg / cm3and most preferably of at most 90 mg / cm3.

[0028] Preferably, the first heater is configured to heat a surface (e.g. an internal surface) of the garniture tongue.

[0029] Preferably, the first heater is configured to heat the portion of the garniture tongue (e.g. the surface of the garniture tongue) above 40°C, preferably above 70°C, more preferably above 70°C and equal to or below 150°C, more preferably 75°C to 150°C, more preferably 80°C to 150°C, more preferably 85°C to 150°C, more preferably 90°C to 150°C. Other preferable ranges include greater than 75°C, greater than 80°C, greater than 85°C, greater than 90°C, greater than 95°C, greater than 100°C, 75°C to 145°C, 75°C to 140°C, 75°C to 130°C, 80°C to 145°C, 80°C to 140°C, 80°C to 135°C, 80°C to 130°C, 85°C to 145°C, 85°C to 140°C, 85°C to 135°C, 85°C to 130°C, 90°C to 145°C, 95°C to 140°C, 95°C to 135°C, 95°C to 140°C, 70°C to 110°C, 75°C to 110°C, or 80°C to 110°C.

[0030] According to possible embodiments, the temperature is greater than 40°C and below 90°C. Further preferable ranges include less than 90°C, less than 85°C, greater than 40°C and less than 85°C, greater than 70°C and less than 90°C, greater than 70°C and less than 85°C.

[0031] Advantageously, it has been found that a higher temperature results in a lower build-up of residuals within the garniture tongue, and thus a lower occurrence of quality defects in the produced filter rod. The above lower limits of temperature, in particular above 70°C, have been found to be particularly effective at reliably preventing the accumulation of residuals, derived from natural fibres and binder, along the entire length of the garniture tongue. However, it has also been found that too high temperatures can lead to undesirable heating of the filter rod itself, e.g. melting and loosening of binder in the filter material. The foregoing ranges, have been found to provide a particularly effective balance between these factors, resulting in a high-quality filter rod. It should be noted that the aforementioned temperatures may not be suitable for filters made from alternative filter materials. For instance, filters based on cellulose acetate typically use hot melt adhesives to secure their wrapping material, and hot melt adhesives should be cooled upon application to improve their adhesion.

[0032] The web of filter material may be supplied at speeds of 100 to 500 m / min, i.e. the garniture tongue receives the web of filter material at a speed within this range. As the deposition characteristics of residuals vary dependent on the supply speed, e.g. location and rate of deposition, the heating temperature of the first heater may also be controlled based on the supply speed. In general, higher supply speeds require higher temperatures to reliably prevent the accumulation of residuals. The control of the heating temperature may also take into account the higher operational costs associated with heating to higher temperatures. For example, when the supply speed is between 100 and 200 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 40 to 80°C. When the supply speed is between 200 and 300 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 60 to 90°C. When the supply speed is between 300 and 400 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 80 to 110°C. When the supply speed is between 400 and 500 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 90 to 150°C.

[0033] In further specific examples, when the supply speed is approximately 100 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 40 to 60°C. When the supply speed is approximately 200 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 60 to 80°C. When the supply speed is approximately 300 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 80 to 90°C. When the supply speed is approximately 400 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 90 to 110°C. When the supply speed is approximately 500 m / min, the first heater may be configured to heat the portion of the garniture tongue in the temperature range of 110 to 150°C.

[0034] In some embodiments, the web of filter material may be mechanically processed prior to being received by the garniture tongue. For example, the web of filter material may be crimped and / or processed with any other mechanical processing method, preferably providing a mechanical deformation of the material.

[0035] Preferably, the assembly system further comprises: a wrapping module configured to wrap the filter rod with wrapping material; and an adhesion element application module configured to apply an adhesion element, for example an adhesive, to a seam of the wrapping material wrapped around the filter rod.

[0036] The adhesion element can be selected from one or more of a solvent-based adhesive, a water-based adhesive, polyvinyl acetate, PVAc, or any combinations thereof. If solvent-based adhesives, and PVAc, are allowed to set at low temperatures, slow solvent evaporation rates and increased viscosity can result in uneven application, gaps in the adhesion element layer, and ultimately, weaker overall adhesion. Hence, by heating the garniture tongue, this acts to pre-heat the produced filter rod such that the temperature of the adhesion element is immediately raised upon application, thereby resulting in improved adhesive properties and a higher quality filter particularly at high machine speeds. It should again be noted that assembly systems for conventional filters, such as those made from cellulose acetate, typically utilise holt melt adhesives to secure the seams of the wrapping material. Unlike solvent-based adhesives, hot melt adhesives should be cooled immediately after application to prevent the bonded surfaces from shifting before the bond is fully established.

[0037] In some embodiments, the adhesive may comprise (or consist of) a cold glue or temperature-activated adhesive. Preferably, the assembly system further comprises: a filter seam heater (also indicated as second heater) configured to heat the adhesion element applied to the seam of the wrapping material. In this way, the filter seam heater acts to raise the temperature of the adhesion element, for example the solvent-based adhesive, along the seam of the wrapping material, thereby providing improved adhesive properties and a higher quality filter. It should be noted that, in contrast, assembly systems for conventional filters such as cellulose acetate filters which utilise holt melt adhesives to secure the seam of wrapping material typically incorporate a cooling element which serves to lower the temperature of the holt melt adhesive, enhancing its adhesion properties and ensuring a strong, stable bond.

[0038] Preferably, the filter seam heater is configured to heat to a higher temperature than the first heater, i.e. the temperature of the filter seam heater is higher than the temperature of the first heater. This means that the adhesion element is heated to a higher temperature than the portion of the garniture tongue (e.g. the surface of the garniture tongue). For example, the second heater is configured to heat the adhesion element to at least 250°C, preferably at least or approximately around 280°C, and more preferably at least or approximately around 300°C.

[0039] In some embodiments, the first heater is positioned in the garniture tongue. In other words, the first heater is positioned inside a wall of the garniture tongue, preferably adjacent the internal surface of the garniture tongue.

[0040] Preferably, the first heater comprises a heating wire positioned in the garniture tongue. The heating wire may extend along at least a portion of the length of the garniture tongue, e.g. along the entire length of the tongue, or along at least a portion of the tongue but not along the tongue tip. In this way, a compact heating arrangement is provided which can provide efficient heating of the garniture tongue. In an alternative example, the first heater may comprise a magnetic induction heater including a susceptor positioned in the garniture tongue and an inductor positioned outside or around the garniture tongue. In another alternative example, the first heater may comprise a Peltier heater or a resistive heating element. In some embodiments, the first heater is positioned outside the garniture tongue, and wherein the first heater is configured to heat the portion of the garniture tongue with or without contact of the first heater with the garniture tongue. For example, the first heater may comprise a hot gun, i.e. a hot air blower, which is configured to direct heated air at the garniture tongue. Alternatively, the first heater may be configured to heat a liquid having a liquid supply path which extends through the garniture tongue such that the heated liquid heats the garniture tongue.

[0041] Preferably, the assembly system further comprises at least one temperature sensor configured to measure the temperature of the garniture tongue and provide feedback control for the first heater. That is, the first heater is configured to be controlled based on the temperature measured by the temperature sensor, thereby ensuring that the garniture tongue is held at an optimal temperature to optimise the quality of the produced filter. Preferably, the temperature sensor is arranged to measure the temperature at or adjacent the surface of the garniture tongue.

[0042] Preferably, the at least one temperature sensor is arranged as close as possible to the surface of the garniture tongue that is in contact with the filter material. For example, the at least one temperature sensor may be arranged closer to the surface of the garniture tongue that contacts the filter material than the opposite surface of the garniture tongue that does not contact the filter material. In particular, the at least one temperature sensor may be arranged less than 4 mm from the surface of the garniture tongue that is in contact with the filter material, e.g. between 4 mm to 1 mm from the surface of the garniture tongue that is in contact with the filter material. In one example, channels or suitable passages can be provided in the garniture tongue body so that the sensor can be arranged close (for example slightly below) with respect to the surface that is in contact with the filter material.

[0043] The temperature sensor may be located adjacent the first heater. In some examples, the temperature sensor may be located at or adjacent the tongue tip, at or adjacent the inlet of the garniture tongue, or at or adjacent a midsection of the garniture tongue.

[0044] Preferably, the garniture tongue comprises a tongue tip at the downstream end of the garniture tongue, and wherein the first heater is positioned upstream of the tongue tip. That is, the first heater does not extend adjacent or along the tongue tip, i.e. the first heater is positioned along the garniture tongue such that the first heater does not overlap with the tongue tip. For example, the first heater may be positioned between, e.g. substantially midway between, the upstream and downstream ends (e.g. inlet and outlet) of the garniture tongue. Alternatively, the first heater may be positioned at or adjacent the inlet of the garniture tongue. It has been found that residuals from the filter materials typically do not accumulate at the tongue tip due to the higher temperatures and pressures at the tongue tip. Hence, it is advantageous to position the first heater upstream of the tongue tip where residuals are more prone to accumulating. As the tongue tip is already hot, there is also a risk that heating the tongue tip using the first heater could lead to burning of the filter material or other undesirable effects.

[0045] It should be noted that the expressions "upstream" and "downstream" as used in this description, refer to a direction of movement of the web from a filter material supply module (e.g. a bobbin or a bale of filter material from which the web is fed) towards a cutting station or towards an outfeed end of the assembly system.

[0046] It will be appreciated that the assembly system may comprise a plurality of first heaters. The plurality of first heaters may be arranged at different positions with respect to the garniture tongue, e.g. according to the above-described examples, and / or may respectively comprise different heater types, e.g. according to the above-described examples. The assembly system may also comprise a plurality of temperatures sensors respectively associated with the plurality of first heaters.

[0047] According to possible embodiments, a plurality of first heaters are provided, preferably to provide different heating zones of the garniture tongue. The plurality of heaters, e.g. two or more heaters or three or more heaters, can be provided along the longitudinal extension of the garniture tongue. In other words, two or more heating areas, preferably three or more heating areas are provided along the longitudinal extension of the garniture tongue. It will be appreciated that the heaters can be arranged at different positions, one next to the other, or by including spaces between at least two or more of them.

[0048] One or more temperature sensor can be provided for each heater of the plurality of heaters.

[0049] As mentioned above, according to possible embodiments the plurality of first heaters defines heating zones, preferably arranged along the length (longitudinal extension) of the garniture tongue. The heating zones may be independently controlled. More in detail, according to possibile embodiments, the plurality of first heater can be independently activated and / or the temperature of each first heater can be independently controlled.

[0050] Preferably, the assembly system further comprises a filter material supply module, wherein the filter material supply module is configured to supply the web of filter material to the garniture tongue. For example, the filter material supply module may comprise a bobbin for holding the web of filter material, or the filter material may be arranged in bales, and a conveyor system, e.g. a system of rollers, for supplying the web of filter material from the bobbin or bale to the garniture tongue.

[0051] In one example, the garniture tongue may comprise or consist of stainless steel. Additionally or alternatively, the garniture tongue may comprise or consist of ceramic material and / or the garniture tongue may be provided with a ceramic coating on the surface configured for contact with the filter material. Additionally or alternatively, the garniture tongue may be made of a plurality of parts connected one to another, the plurality of parts may be made of the same material or different materials.

[0052] According to a second aspect of the invention, there is provided a method of producing a filter for a tobacco stick, comprising the steps of: supplying a web of filter material to a garniture tongue, wherein the web of filter material comprises natural fibres; heating at least a portion of the garniture tongue using a first heater; and shaping the web of filter material into a filter rod with the garniture tongue.

[0053] Preferably, the portion of the garniture tongue (e.g. the surface of the garniture tongue) is heated above 40°C, preferably above 70°C, more preferably above 70°C and equal to or below 150°C, more preferably 75°C to 150°C, more preferably 80°C to 150°C, more preferably 85°C to 150°C, more preferably 90°C to 150°C,. Other preferable ranges include, greater than 75°C, greater than 80°C, greater than 85°C, greater than 90°C, greater than 95°C, greater than 100°C,

[0054] 75°C to 145°C, 75°C to 140°C, 75°C to 130°C, 80°C to 145°C, 80°C to 140°C,

[0055] 80°C to 135°C, 80°C to 130°C, 85°C to 145°C, 85°C to 140°C, 85°C to 135°C,

[0056] 85°C to 130°C, 90°C to 145°C, 95°C to 140°C, 95°C to 135°C, 95°C to 140°C,

[0057] 70°C to 110°C, 75°C to 110°C, or 80°C to 110°C.

[0058] According to possible embodiments, the temperature is greater than 40°C and below 90°C. Further preferable ranges include less than 90°C, less than 85°C, greater than 40°C and less than 85°C, greater than 70°C and less than 90°C, greater than 70°C and less than 85°C.

[0059] Preferably, the method further comprises: wrapping the filter rod with a wrapping material using a wrapping module; and applying an adhesion element to a seam of the wrapping material wrapped around the filter rod using an adhesion element application module, wherein the adhesion element can be selected from one or more of a solvent-based adhesive, a water-based adhesive, polyvinyl acetate, PVAc, or any combinations thereof.

[0060] Preferably, the method further comprises: heating the adhesion element applied to the seam of the wrapping material using a second heater, i.e. a filter seam heater. Preferably, the filter seam heater heats to a higher temperature than the first heater, e.g. the filter seam heater heats the adhesive to at least 250°C, preferably at least or approximately around 280°C, and more preferably at least or approximately around 300°C. It will be understood that the preferable features of the first aspect also apply to the second aspect mutatis mutandis.

[0061] BRIEF DESCRIPTION OF DRAWINGS

[0062] Aspects of the present invention will now be described, by way example, by reference to the drawings, in which:

[0063] Figure 1 is a schematic diagram of an assembly system for producing a filter for a tobacco stick;

[0064] Figures 2A and 2B are schematic views of a garniture tongue of the assembly system illustrating the accumulation of residuals;

[0065] Figure 3 is a schematic view of the garniture tongue including a first heater for heating the garniture tongue; and

[0066] Figures 4A and 4B are schematic views of a garniture tongue including an alternative arrangement of first heaters.

[0067] DETAILED DESCRIPTION

[0068] Figure 1 is a schematic diagram of an assembly system 200 for producing a filter 100 for a tobacco stick. The assembly system 200 may also be referred to as a manufacturing pipeline or assembly machinery. To produce a filter 100, a web of filter material 20 is fed into a funnel F from a first bobbin (not shown) via pulleys P (also referred to as a conveyor system). It is noted that although specific reference to a bobbin is disclosed, the filter material 20 can be stored in different ways, for example in one or more bales. The combination of the first bobbin and pulleys P may be referred to as a filter material supply module. The web of filter material 20 is an elongate tape or continuous sheet that can be fed through the assembly system 200.

[0069] The web of filter material comprises natural fibres, such as one or more of wood fibres, cotton fibres, leaf fibres, e.g. abaca or sisal fibres, bast fibres, e.g. jute, hemp, flax or kenaf fibres, and regenerated cellulose, e.g. viscose and / or lyocell fibres. In some embodiments, the natural fibres comprise or consist of cellulose pulp, e.g. wood pulp, preferably being obtained by a kraft process.

[0070] In particular, the filter material may comprise a non-woven substrate comprising natural fibres and a binder, wherein the natural fibres preferably represent 85% to 95% by weight of the non-woven substrate, and the binder preferably represents 5% to 15% by weight of the non-woven substrate. For example, the weight content of natural fibres may be comprised between 86.9% and 95%, in particular between 90% and 93%, and the weight content of the binder may comprised between 5% and 13.1 %, in particular between 7% and 10%.

[0071] The non-woven substrate can be obtained by short fibre airlaid technology. The average length of the natural fibres, according to some embodiments, is at most 3.5 mm, preferably at most 3.0 mm and most preferably at most 2.8 mm, and / or the average length of the natural fibres is at least 2.0 mm, preferably at least 2.3 mm and most preferably at least 2.5 mm.

[0072] The binder may comprise at least one binding agent that is a water-based polymer emulsion. In some embodiments, the binder may be selected from one or more of an aqueous copolymer dispersion of ethylene vinyl acetate, EVA, and a polyvinyl acetate, PVAc, a cellulose derivative, such as ethyl / methyl cellulose, hydroxyethylAmethyl cellulose and / or carboxymethyl cellulose and / or a polysaccharide (or a derivative of a polysaccharide) such as dextrin or starch.

[0073] In some embodiments, the binder comprises a combination of EVA and PVAc, wherein the weight ratio of EVA to PVAc is preferably comprised between 70:30 and 30:70, more preferably between 60:40 and 40:60, and even more preferably between 55:45 and 45:55.

[0074] The web of filter of material 20 may have a thickness between 0.3 mm and 1.3 mm and / or a basis weight between 40 g / m2and 60g / m2and / or a width comprises between 50 mm and 240 mm. The web of filter of material 20 may have a volume density of at least 50 mg / cm3, preferably of at least 55 mg / cm3and most preferably of at least 60 mg / cm3, or at least 62 mg / cm3, and / or a volume density of at most 110 mg / cm3, preferably of at most 100 mg / cm3and most preferably of at most 90 mg / cm3.

[0075] The web of filter material 20 may be a crimped web of filter material 20. That is, the web of filter material 20 may be crimped by a crimping machine (not shown) prior to being fed through pulleys P, thereby increasing the surface area of the filter material and improving filtration in use. The web of filter material 20 may additionally or alternatively be an embossed web of filter material 20. That is, the web of filter material 20 may be embossed by an embossing machine (not shown) prior to being fed through pulleys P, thereby modifying the texture of the filter material. More generally, the web of filter material 20 may be mechanically processed prior to being fed into the funnel F.

[0076] The purpose of the funnel F is to guide the web of filter material 20 into a garniture tongue T. The garniture tongue T, having an aperture with a width less than that of the web of filter material 20, rolls and folds the web of filter material 20 together to form a cylindrical interior of the filter 100, which may also be referred to as a filter rod. The garniture tongue T ensures uniform distribution and compaction of the filter material, contributing to the overall consistency and quality of the filter rod. The garniture tongue T may be made of stainless steel. However, different materials are also not excluded, for example the garniture tongue T may be made at least partially of ceramic material or it can be provided with a ceramic coating on the surface intended to be in contact with the filter material. According to possible embodiments, the garniture tongue may be made of a plurality of parts connected one to another, the plurality of parts may be made of the same material or different materials.

[0077] Wrapping material 30, such as paper, is also fed into the garniture tongue T via a second bobbin B.

[0078] According to possible embodiments, an additional purpose of the garniture tongue T is to prepare the material for being wrapped, for example to wrap the cylindrical filter interior with a single layer of wrapping material 30. For example, the garniture tongue T can be provided with specific portions or additional elements that are responsible for wrapping which may be referred to as a wrapping module. Alternatively, the assembly system 200 may comprise a separate wrapping module that is located downstream of the garniture tongue T.

[0079] An adhesion element application module 50 is located adjacent the downstream end of the garniture tongue T. It will be understood that the adhesion element application module 50 is located downstream of the wrapping module. The adhesion element application module 50 is configured to apply an adhesion element to a seam of the wrapping material 30, thereby bonding overlapping surfaces of the wrapping material 30 together to secure the wrapping material 30 around the cylindrical interior of the filter 100. The adhesion element may be a solvent-based or water-based adhesive, for example a polyvinyl acetate, PVAc can be used. In some embodiments, the adhesive may be a cold glue or temperature-activated adhesive.

[0080] For these types of adhesion element, it is advantageous to heat the adhesion element upon application, e.g. in order to increase the solvent evaporation rate and raise the solvent viscosity. This ensures an even and consistent application of adhesion element along the seam and increases the setting rate, thereby improving the overall adhesion properties. To this end, the assembly system 200 preferably further comprises a filter seam heater (second heater) 60, which may also be referred to as a heating bar, configured to heat the adhesive applied along the seam of the wrapping material 30. In order to optimise the setting process, the second heater 60 may be configured to heat the adhesive to at least 250°C, preferably at least 280°C, and more preferably at least or approximately around 300°C.

[0081] The wrapped and glued filter interior is fed towards a rotating blade RB which cuts the continuous wrapped filter interior into individual cylindrical filters 100. The filters 100 are for use in tobaccos sticks, such as cigarettes or heat-not-burn articles. It has been found that producing filters 100 in the manner described is associated with significant accumulation of residuals from the natural filter material 20 within the garniture tongue T. In particular, as illustrated in Figures 2A and 2B which show two cutaway views of the garniture tongue T, residuals R accumulate on the internal surface of the garniture tongue T due to the friction and contact forces between the web of filter material 20 and the garniture tongue T. The location of deposition of residuals R varies depending on the supply speed of the web of filter material 20, but the most significant build-up of residuals R has typically been found to occur upstream of the tongue tip TT (or finger) of the garniture tongue T, and in particular approximately midway between the tongue tip TT and the inlet of the garniture tongue T. It will be understood that the tongue tip TT is the downstream end of the garniture tongue T where the contact forces between the garniture tongue T and the web of filter material 20 are at a maximum. The residuals R are primarily composed of binder from the web of filter material 20 but may also include some natural fibres from the web of filter material 20. The accumulation of residuals R has been found to result in quality defects in the cylindrical interior of the filter 100 and machine runability issues as the manufacturing process must be repeatedly stopped in order to clean the garniture tongue T.

[0082] Accordingly, to overcome these issues, the assembly system 200 includes a first heater 40 that is configured to heat at least a portion of the garniture tongue T. In particular, the first heater 40 is configured to heat the surface of the garniture tongue T. Heating of the garniture tongue using the first heater 40 results in softening and / or melting of the accumulated residuals R such that the movement of the web of filter material 20 or formed filter rod through the garniture tongue T acts to wipe and remove any accumulated residuals R from the surface of the garniture tongue T. The occurrence of quality defects in the produced filter rod is therefore reduced and the requirement to regularly stop the machine and clean the garniture tongue is avoided, thereby enhancing the quality and production efficiency of the filter 100. A further advantage of heating the garniture tongue T using the first heater 40 is that the bonding of the applied adhesion element along the seam of wrapping material 30 is improved. In particular, as noted above, it is advantageous to heat solvent-based adhesives such as PVAc to improve their adhesion properties. Heating of the garniture tongue T using the first heater 40 acts to pre-heat the produced filter rod, such that the temperature of the applied adhesive is immediately raised resulting in a stronger and more reliable bond, and a higher quality filter 100.

[0083] As better illustrated in Figure 3, which shows a cutaway view of the garniture tongue T, the first heater 40 is located in the garniture tongue T. In other words, the first heater 40 is located within a wall of the garniture tongue T, e.g. adjacent the internal surface of the garniture tongue T. This provides efficient heating of the internal surface of the garniture tongue T. The first heater 40 is also located upstream from the tongue tip TT of the garniture tongue T. In particular, the first heater 40 is positioned such that the first heater 40 does not overlap with the tongue tip TT. This positioning is preferable in view of the residuals R predominantly accumulating away the tongue tip TT, as the increased contact forces at the tongue tip TT already acts to heat any residuals R such that further heating is less desirable and in fact may result in burning of the filter material.

[0084] In particular, in the embodiment of Figure 3, the first heater 40 is positioned below the surface of the garniture tongue T and extends along at least a portion of the length of the garniture tongue T, e.g. extends along the midsection of the length garniture tongue T such that the first heater 40 does not overlap with the upstream and / or downstream ends of the length of the garniture tongue T, specifically the first or last 5, 10, 15, 20 or 25% of the length of the garniture tongue T.

[0085] The skilled person will understand, however, that the positioning of the first heater 40 may vary. For example, in alternative embodiments, the first heater 40 may be located outside or external to the garniture tongue T, and may be configured to heat the garniture tongue T with or without contact of the first heater 40 with the garniture tongue T. In further additional or alternative embodiments, the position of the first heater 40 along the length of the garniture tongue T may also vary. For example, the first heater 40 may be arranged at or adjacent the inlet of the garniture tongue T, i.e. at the upstream end of the garniture tongue T, or the first heater 40 may be arranged at or adjacent the outlet of the garniture tongue T, i.e. at the downstream end or tongue tip TT of the garniture tongue T.

[0086] In further possible embodiments, a plurality of first heaters 40, preferably two or more heaters, more preferably three or more heaters are arranged along the length (the longitudinal extension of the garniture tongue). The position of the heaters 40 along the length of the garniture tongue T may vary. For example, one of the plurality of the first heaters 40 may be arranged at or adjacent the inlet of the garniture tongue T, i.e. at the upstream end of the garniture tongue T, and / or another one of the plurality of first heaters 40 may be arranged at or adjacent the outlet of the garniture tongue T, i.e. at the downstream end or tongue tip TT of the garniture tongue T. Additional first heaters 40, can be arranged to provide consecutives or spaced additional heating zones along the length of the garniture tongue.

[0087] The first heater 40 is a resistive wire heater. The use of a resistive wire provides a compact heating arrangement which can efficiently heat the garniture tongue. It will again, however, be appreciated that the type of heater may vary. In one alternative example, the first heater 40 may be an inductive heater comprising a susceptor positioned in the garniture tongue T and an inductor positioned outside or around the garniture tongue T. In another alternative example, the first heater 40 may be a Peltier heater. In another example, the first heater 40 may be a hot gun, i.e. a hot air blower, which is configured to direct heated air at the garniture tongue T. In another example, the first heater 40 may be configured to heat a liquid having a liquid supply path which extends through the garniture tongue T such that the heated liquid heats the garniture tongue T.

[0088] The first heater 40 may be configured to heat the garniture tongue T (e.g. the surface of the garniture tongue) to a temperature greater than 40°C, preferably greater than 70°C, more preferably to a temperature equal to or below 150°C. Further preferable ranges include greater than 75°C, greater than 80°C, greater than 85°C, greater than 90°C, greater than 95°C, greater than 100°C, 75°C to 150°C, 80°C to 150°C, 85°C to 150°C, 90°C to 150°C, 75°C to 145°C, 75°C to

[0089] 140°C, 75°C to 130°C, 80°C to 145°C, 80°C to 140°C, 80°C to 135°C, 80°C to

[0090] 130°C, 85°C to 145°C, 85°C to 140°C, 85°C to 135°C, 85°C to 130°C, 90°C to

[0091] 145°C, 95°C to 140°C, 95°C to 135°C, 95°C to 140°C, 70°C to 110°C, 75°C to

[0092] 110°C, or 80°C to 110°C.

[0093] According to possible embodiments, the temperature is greater than 40°C and below 90°C. Further preferable ranges include less than 90°C, less than 85°C, greater than 40°C and less than 85°C, greater than 70°C and less than 90°C, greater than 70°C and less than 85°C.

[0094] In general, a higher temperature has been found to be desirable as it results in a reduced build-up of residuals R within the garniture tongue T, and thus a lower occurrence of quality defects in the produced filter rod. The above lower limits of temperature, in particular greater than 70°C, have been found to be particularly effective at preventing the accumulation of residuals R from the web of filter material 20 along the entire length of the garniture tongue T. It has also been found that too high temperatures can lead to undesirable heating of the filter rod itself, e.g. melting and loosening of binder in the filter material. The above upper limits have been found to provide a particularly effective balance between these competing factors.

[0095] The web of filter material 20 may be supplied to the garniture tongue T at a speed within the range of 100 to 500 m / min. As the deposition characteristics of residuals vary dependent on the supply speed, the heating temperature of the first heater may also be controlled based on the supply speed. In general, higher supply speeds require higher temperatures to reliably prevent the accumulation of residuals. The control of the heating temperature may also take into account the higher operational costs associated with heating to higher temperatures. For example, when the supply speed is between 100 and 200 m / min, the first heater may be configured to heat the portion of the garniture tongue between 40 and 80°C. When the supply speed is between 200 and 300 m / min, the first heater may be configured to heat the portion of the garniture tongue between 60 and 90°C. When the supply speed is between 300 and 400 m / min, the first heater may be configured to heat the portion of the garniture tongue between 80 and 110°C. When the supply speed is between 400 and 500 m / min, the first heater may be configured to heat the portion of the garniture tongue between 70 and 150°C, preferably between 90 and 150°C. It should also be noted that the aforementioned temperatures may not be suitable for conventional filters made from alternative filter materials. For instance, filters based on cellulose acetate typically use hot melt adhesives to secure their wrapping material after formation of the filter rod within a garniture tongue. However, unlike solvent-based adhesives, hot melt adhesives should be cooled immediately after application to aid setting and to prevent the bonded surfaces from shifting before the bond is fully established. Assembly systems for cellulose acetate filters therefore typically include a cooling bar to lower the temperature of the applied adhesive.

[0096] The assembly system 200 further comprises a temperature sensor 70 for measuring the temperature of the garniture tongue T, e.g. the temperature of the surface of the garniture tongue T. The first heater 40 is configured to be controlled based on the temperature measured by the temperature sensor 70. That is, the temperature sensor 70 provides feedback control for the first heater 40. This ensures that the garniture tongue T is heated to an appropriate temperature, e.g. a temperature within the aforementioned temperature ranges. It will, however, be appreciated by the skilled person that the presence of the temperature sensor 70 and implementation of feedback control is optional.

[0097] The temperature sensor 70 shown in Figures 1 and 3 is located within the garniture tongue T adjacent the first heater 40. However, it will be appreciated that the location of the temperature sensor 70 may vary.

[0098] Figures 4A and 4B are schematic views of a garniture tongue T of an assembly system 202 according to an alternative embodiment of the invention. Figure 4B show a cross-sectional view looking along the direction X illustrated in Figure 4A. In particular, in this alternative embodiment, a plurality of first heaters 401 , 402, 403 are provided which are each configured to heat the garniture tongue T. The plurality of first heaters 401 , 402, 403 are arranged to heat a midsection of the length of the garniture tongue T. In particular, the plurality of first heaters 401 , 402, 403 are arranged along the length of the garniture tongue T such that the plurality of first heaters 401 , 402, 403 do not overlap with the tongue tip TT. This is advantageous as it avoids overheating of the tongue tip TT and concentrates the heating on the portion of the garniture tongue T most susceptible to build-up of residuals R.

[0099] The plurality of first heaters 401 , 402, 403 are spaced around the garniture tongue T. This results in more even and consistent heating of the garniture tongue T.

[0100] In the depicted embodiment, the plurality of first heaters 401 , 402, 403 are plateshaped heating elements, but the skilled person will appreciate that the type and / or shape of the plurality of first heaters 401 , 402, 403 may vary, e.g. in accordance with various types of heaters discussed previously. It will also be appreciated that the number of the plurality of first heaters may vary.

[0101] The assembly system 202 of this embodiment also includes a temperature sensor 702 located at or adjacent the tongue tip TT. The tongue tip TT may be indirectly heated by the plurality of first heaters 401 , 402, 403 via conduction along the garniture tongue T. Hence, by locating the temperature sensor 702 at or adjacent the tongue tip TT, it can be ensured that the tongue tip TT does not overheat. In other examples, the location of the temperature sensor 702 may vary, e.g. as previously discussed.

[0102] It will be appreciated by the skilled person that the other features of the assembly system 200 also similarly apply to the assembly system 202.

Claims

23CLAIMS1 . An assembly system for a filter for a tobacco stick, comprising: a web of filter material comprising natural fibres; a garniture tongue arranged to receive the web of filter material and configured to shape the web of filter material into a filter rod for a tobacco stick; and a first heater configured to heat at least a portion of the garniture tongue.

2. The assembly system of claim 1 , wherein the web of filter material further comprises a binder.

3. The assembly system of claim 2, wherein the binder comprises one or more of: an aqueous copolymer dispersion of ethylene vinyl acetate, EVA, and polyvinyl acetate, PVAc; a cellulose derivative, preferably ethyl / methyl cellulose, hydroxyethylAmethyl cellulose and / or carboxymethyl cellulose; and a polysaccharide or a derivative of a polysaccharide, preferably dextrin and / or starch.

4. The assembly system of claim 2 or claim 3, wherein the web of filter material comprises a non-woven substrate comprising the natural fibres and the binder.

5. The assembly system of any of claims 2 to 4, wherein the weight content of natural fibres is comprised between 85% and 95%, preferably between 86.9% and 95%, more preferably between 90% and 93%, and the weight content of the binder is comprised between 5% and 15%, preferably between 5% and 13.1%, more preferably between 7% and 10%, and / or wherein the natural fibres comprise or consist of wood pulp, the wood pulp preferably being obtained by the kraft process.

6. The assembly system of any preceding claim, wherein the first heater is configured to heat the portion of the garniture tongue above 40°C, preferably above 70°C, more preferably above 70°C and equal to or below 150°C, morepreferably 75°C to 150°C, more preferably 80°C to 150°C, more preferably 85°C to 150°C, more preferably 90°C to 150°C.

7. The assembly system of any preceding claim, further comprising: a wrapping module configured to wrap the filter rod with wrapping material; and an adhesion element application module configured to apply an adhesion element to a seam of the wrapping material wrapped around the filter rod, wherein the adhesion element is selected from one or more of a solvent-based adhesive, a water-based adhesive, polyvinyl acetate, PVAc, or any combinations thereof.

8. The assembly system of claim 7, further comprising: a filter seam heater configured to heat the adhesion element applied to the seam of the wrapping material, preferably wherein the filter seam heater is configured to heat to a higher temperature than the first heater.

9. The assembly system of any preceding claim, wherein the first heater is positioned in the garniture tongue.

10. The assembly system of claim 9, wherein the first heater comprises a heating wire positioned in the garniture tongue.11 . The assembly system of any of claims 1 to 9, wherein the first heater is positioned outside the garniture tongue, and wherein the first heater is configured to heat the portion of the garniture tongue with or without contact of the first heater with the garniture tongue.

12. The assembly system of any preceding claim, further comprising a temperature sensor configured to measure the temperature of the garniture tongue and provide feedback control for the first heater.

13. The assembly system of any of the preceding claim, wherein the garniture tongue comprises a tongue tip at the downstream end of the garniture tongue, and wherein the first heater is positioned upstream of the tongue tip.

14. A method of producing a filter for a tobacco stick, comprising the steps of:supplying a web of filter material to a garniture tongue, wherein the web of filter material comprises natural fibres; heating at least a portion of the garniture tongue using a first heater; and shaping the web of filter material into a filter rod with the garniture tongue.

15. The method of claim 14, further comprising: wrapping the filter rod with a wrapping material using a wrapping module; and applying an adhesion element to a seam of the wrapping material wrapped around the filter rod using an adhesion element application module, wherein the adhesion element is selected from one or more of a solvent-based adhesive, a water-based adhesive, polyvinyl acetate, PVAc, or any combinations thereof and preferably wherein the method further comprises: heating the adhesion element applied to the seam of the wrapping material using a filter seam heater.

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