WO2016120583A1

WO2016120583A1 - Apparatus and method for filter manufacture

Info

Publication number: WO2016120583A1
Application number: PCT/GB2015/054180
Authority: WO
Inventors: Gary Fallon; Kie Seon PARK
Original assignee: British American Tobacco (Investments) Limited
Priority date: 2015-01-30
Filing date: 2015-12-31
Publication date: 2016-08-04
Also published as: GB201501527D0

Abstract

Apparatus and Method for Filter Manufacture A filter rod for a smoking article comprises an extruded hardened inner core of a first filter material and an outer core of a second filter material which surrounds the inner core. The second filter material is of a softer texture than the first filter material. The filter rod further comprises a plug wrap around the outer core. Also, an apparatus for manufacturing such a filter rod comprises an inner duct having an inlet to receive a first filter material including a plasticiser and an outlet through which the first filter material is expelled. An outer duct has an inlet to receive a second filter material and an outlet through which the second filter material is expelled. The inner duct is disposed within the outer duct to enable formation of a continuous body of filter material comprising an inner core of the first filter material surrounded by an outer core of the second filter material. A wrapping station is disposed proximate the outlets of the inner and outer ducts to provide a plug wrap around the continuous body of filter material. The inner duct includes at least one steam inlet for the introduction of steam into the inner duct to heat the first filter tow material as it is conveyed through the inner duct to form a hardened inner core. Also a method of manufacturing such a filter rod is described.

Description

Apparatus and Method for Filter Manufacture

Technical Field

In this specification there is described an apparatus and method for filter manufacture and, in particular, an apparatus and method for manufacture of filters with a hardened core for use with smoking articles.

Background

Apparatuses and methods for manufacture of smoking article filters are known that comprise a continuous garniture belt that conveys a gathered strand of filter tow material fed onto a continuous band of plug wrap though a tapering garniture duct or "tongue". Within the garniture tongue the garniture belt wraps the plug wrap around the filter tow material and compresses the material into a continuous cylindrical wrapped rod which can subsequently be cut to desired lengths.

Summary

In this specification there are described embodiments of a filter rod for a smoking article comprising an extruded hardened inner core of a first filter material, an outer core of a second filter material surrounding the inner core and of a softer texture than the first filter material, and a plug wrap around the outer core.

The first filter material may comprise cellulose acetate tow which is hardened with a plasticiser. The second filter material may comprise cellulose acetate. The first and second filter materials may both comprise cellulose acetate tow, and the amount of plasticiser entrained in the first filter material may be greater than any amount of plasticiser that may be entrained in the second filter material.

The first filter material and/ or the second filter material may comprise a granular aerosol modifying material.

The present invention also provides a filter rod as described above, and a second filter segment axially aligned with the filter rod and joined thereto by a plug wrap around the filter rod and second filter segment. The present invention also provides a smoking article comprising a tobacco rod and a filter rod or filter as described above, joined to one end of the tobacco rod.

The present invention also provides an apparatus for manufacturing a dual core filter rod for smoking articles, the apparatus comprising an inner duct having an inlet to receive a first filter material including a plasticiser and an outlet through which the first filter material is expelled, an outer duct having an inlet to receive a second filter material and an outlet through which the second filter material is expelled, wherein the inner duct is disposed within the outer duct to enable formation of a continuous body of filter material comprising an inner core of the first filter material surrounded by an outer core of the second filter material, and a wrapping station disposed proximate the outlets of the inner and outer ducts to provide a plug wrap around the continuous body of filter material, wherein the inner duct includes at least one steam inlet for the introduction of steam into the inner duct to heat the first filter tow material as it is conveyed through the inner duct to form a hardened inner core.

The apparatus as described above includes an outer duct that tapers between the inlet and the outlet. The inner duct may taper between the inlet and the outlet. The outlet of the inner duct may be disposed within the outer duct.

The outer duct may have first and second sections, wherein the first section tapers from the inlet to the second section, and the second section is of constant cross-section, and wherein the outlet of the inner duct is disposed within the second section of the outer duct.

The inner duct may be disposed coaxially with the outer duct.

The steam inlet may be provided in a side wall of the inner duct between the inlet and outlet.

The apparatus as described above may comprise a steam supply pipe connected to the at least one steam inlet and configured to supply steam directly and exclusively into the inner duct through the steam inlet. The outlet of the inner duct may have a removable die having an outlet aperture through which the first filter material is expelled.

At least a portion of an outer surface of the inner duct may be provided with a thermally insulating layer.

The apparatus may include a wrapping station which comprises a spool of a web of plug wrap, a tapering guide duct to receive the continuous and a continuous driven belt extending through the tapering guide duct to convey the plug wrap web through the tapering guide duct so that the continuous body of filter material is fed onto the web of plug wrap and the web of plug wrap is wrapped around the core and surrounding layer as it is conveyed through the tapering guide duct.

The apparatus may further comprise a cutting station configured to cut the continuous wrapped filter rod into discrete filter rods.

The present invention also provides a method of manufacturing a dual core filter rod for smoking articles, the method comprising feeding a first filter material including a plasticiser into an inlet of an inner duct and conveying the first filter material through the inner duct and out of an outlet of the inner duct, feeding a second filter material into an inlet of an outer duct and conveying the second filter material through the outer duct and out of an outlet of the outer duct, wherein the inner duct is disposed within the outer duct so that a continuous body of filter material is formed comprising an inner core of the first filter material surrounded by an outer core of the second filter material, introducing steam into the inner duct through at least one steam inlet formed therein to heat the first filter tow material as it is conveyed through the inner duct to at least partially cure the plasticiser to form a hardened inner core, and providing a plug wrap around the continuous body of filter material at a wrapping station disposed proximate the outlets of the inner and outer ducts.

The inner duct may taper between the inlet and the outlet, and the method may further comprise compressing the first filter material to form the inner core as it is conveyed through the inner duct. The outer duct may taper between the inlet and the outlet, and the method may further comprise compressing the second filter material to form the outer core as it is conveyed through the outer duct.

The method may comprise expelling the first filter material out of the outlet of the inner duct within the outer duct.

The method may comprise feeding steam via the steam inlet through a side wall of the inner duct between the inlet and outlet.

The method may comprise feeding steam via a steam supply pipe connected to the at least one steam inlet directly and exclusively into the inner duct.

The method may comprise providing cellulose acetate tow impregnated with plasticiser as the first filter material. The method may comprise providing a cellulose acetate tow as the second filter material.

The method may comprise heating the first filter material within the inner duct with steam at between 100 - 200 degrees Celsius.

The method may further comprise cutting the continuous wrapped filter rod into discrete filter rods.

An internal passage of the inner duct may include a tapered section which narrows in a direction towards the outlet of the inner duct. The outer dimension of the inner duct may include a tapered section which narrows in a direction towards the outlet of the inner duct.

A distance between an outer surface of the inner duct and an inner surface of the outer duct may reduce along at least a part of the length of the outer duct in a direction towards the outlet of the inner duct.

The distal end of the inner duct may be positioned downstream of the outlet of the outer duct. The inner duct may extend entirely through the length of the outer duct. The method may comprise expelling the second filter material from the inner duct downstream of the outlet of the outer duct.

Brief Description of the Drawings

Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure ι schematically shows a cross-section of a first embodiment of an apparatus for manufacturing filter rods;

Figure 2 shows a cross-sectional view of the apparatus of Figure ι along the line X-X; Figure 3 shows a cross-sectional view along the line Y-Y as shown in Figure 1, of a filter rod manufactured using the apparatus of Figure 1;

Figure 4 shows a smoking article including a filter made from a filter rod shown in Figure 3;

Figure 5 shows a cross-sectional view of a second embodiment of a smoking article including a filter made from a filter rod shown in Figure 3; and

Figure 6 shows a cross-sectional view of an end portion of an alternative configuration of inner duct of the apparatus of Figure 1. Detailed Description

Referring now to Figure 1, an apparatus 10 of a first embodiment is shown for the manufacture of filter rods and comprises an inner duct 11 having an inlet 12, an outlet 13 and a hollow central bore 14. The inner duct 11 comprises a first section 11a that is circular in cross-section and that narrows from the inlet 12 to an intermediate point 15, and a second section 11b of constant circular cross-section extending from the intermediate point 15 to the outlet 13. A plurality of steam inlets 16a extend though the side wall of the inner duct 11. Steam feed pipes 16 are connected to the steam inlets 16a to allow steam to be supplied to the inside of the inner duct 11. The inner duct 11 is disposed within an outer duct 17. The outer duct 17 includes an inlet 18, an outlet 19 and a hollow central bore 20. The outer duct 17 comprises a first section 17a that narrows from the inlet 18 to an intermediate point 21, and a second section 17b of constant circular cross-section extending from the intermediate point 21 to the outlet 19. The outlet 13 of the inner duct 11 is located within the second section 17b of the outer duct 17. Figure 2 shows the circular bores 14, 20 of the inner and outer ducts 11, 17 respectively.

The steam feed pipes 16 extend through the bore 20 of the outer duct 17 and to the steam inlets 16a which extend through the side wall of the outer duct 17.

A wrapping station 22 is provided adjacent to the outlet 19 of the outer duct 17 and includes a tapering guide duct 23 having an inlet 24 and an outlet 25. A continuous garniture belt 26 extends through the guide duct 23 and over a plurality of rollers 27. At least one of the rollers 27 is driven to drive the continuous garniture belt 26 in the direction shown by arrows 28. A continuous web of plug wrap 29 is fed from a spool 30 to the inlet 24 of the guide duct 23 and is conveyed through the guide duct 23 by the moving garniture belt 26.

A cutting station 31 is provided adjacent to the outlet 25 of the guide duct 23 and includes a cutting blade 32.

In use, filter tow material 33, such as cellulose acetate tow mixed with a plasticiser, is fed into the inlet 12 of the inner duct 11. The filter material 33 is mixed with the plasticiser, such as triacetate, in a ratio of about 17% by weight, although other ratios of plasticiser may be used within the scope of the invention, such as between 4% and 50% by weight. The filter tow 33 with entrained plasticiser may be conveyed through the first inner duct section 11a using jets of compressed air (not shown). The filter tow material 33 is compressed as it passes through the tapering inner duct section 11a and is formed into a continuous cylindrical rod within the second inner duct section lib.

As the filter tow material 33 passes through the inner duct 11, dry steam S at around 170 degrees Celsius is supplied to the bore 14 of the inner duct 11 through the steam feed pipes 16. The steam S permeates and heats the filter tow material which cures or at least partially cures the entrained plasticiser. This causes the continuous cylindrical rod formed in the second inner duct section lib to harden to form a stiff continuous rod. The continuous cylindrical rod is expelled out of the outlet 13 of the inner duct 11.

Simultaneously, a second filter tow material 34 is fed into the inlet 18 of the outer duct 17 and is conveyed through the bore 20 thereof. The second filter tow material 34 may be conveyed through the outer duct 17 using jets of compressed air (not shown). The second filter tow material 34 is compressed around the outer surface of the inner duct 11 as it is conveyed through the tapering first section 17a of the outer duct 17, and is then formed into a continuous generally tubular configuration in cross-section as it is conveyed through the second section 17b of the outer duct 17, around the second section lib of the inner duct 11. Again, this can be seen more clearly from Figure 2. The second filter tow material 34 contains less plasticiser than the filter tow material 33 conveyed through the inner duct 11. For example, the second filter tow material may comprise cellulose acetate tow with less than 5% by weight of plasticiser. The second filter tow material may not include any plasticiser at all. Also, the second filter tow material 34 is not heated by steam as the filter tow material 33 within the inner duct 11 is. Accordingly, the second filter tow material 34 remains softer than the hardened continuous filter rod formed within the inner duct 11.

As the continuous stiff rod is expelled from the outlet 13 of the inner duct 11, it is surrounded by the tubular second filter tow material 34. This results in a composite dual core continuous filter rod having an inner core 36 of a hardened filter tow material 33 surrounded by an outer core layer 37 of the softer second filter tow material 34.

The continuous composite filter rod then passes to the wrapping station 22 and into the inlet 24 of the guide duct 23. The continuous composite filter rod is received on the web of plug wrap 29 that is disposed on the garniture belt 26. As the continuous composite filter rod passes through the guide duct 23 being driven by the garniture belt, the web of plug wrap 29 is wrapped around the continuous composite filter rod as the guide duct 23 tapers along its length, until the continuous composite filter rod is entirely wrapped with the plug wrap 29. The plug wrap 29 is sealed around the continuous composite filter rod by adhesive (not shown), which may, for example, be either pre-formed on the web of plug wrap 29, or may be applied to the plug wrap 29 by an adhesive applicator (not shown) as part of the wrapping station 22. The continuous wrapped composite filter rod exits the outlet 25 of the guide duct 23. The movement of the driven garniture belt 26 also helps to draw the continuous composite filter rod out of the outlet 19 of the outer duct 17, and generally helps draw the first and second filter tow materials 33, 34 respectively through the inner and outer ducts 11, 17.

After the continuous wrapped dual-core filter rod having an inner core 36 of hardened filter tow material 33 and an outer core 37 of softer tow material 34, exits the outlet 25 of the guide duct 23, it passes to the cutting station 31 where the cutting blade 32 cuts the continuous wrapped filter rod into individual lengths of discrete wrapped filter rods 35. These may be single length filter rods 35 of a size suitable for use in combination with a single tobacco rod to make a single smoking article. Alternatively, the discrete wrapped filter rods 35 may be "2-up", "4-up" or "6-up" rods, or other lengths which are a multiple of a single length filter that would be joined to a tobacco rod in a finished smoking article. Such multiple length filter rods can be supplied to subsequent smoking article manufacturing machinery to be cut to length in later processing steps.

A discrete filter rod 35 of the invention manufactured using the above-described apparatus 10 and method is shown in cross-section in Figure 3. The filter rod 35 is substantially cylindrical and is continuous in cross-section along its length. The filter rod 35 comprises an inner core 36 of hardened tow material 33, and a surrounding outer core layer 37 of softer filter tow material surrounding the inner core 36, with an outer plug wrap 38 enveloping the outer core 27 and providing structural integrity to the filter rod 35.

Figure 4 shows one exemplary configuration of a smoking article 40 incorporating a discrete filter rod 35 as described above. (Although, as described above, in a smoking article the filter component may be a section cut from a multiple length filter rod 35, individual filter rod 35 within the smoking article 40 will be referred to herein as "filter rod 35")· The smoking article 40 comprises a tobacco rod 41 with a filter rod 35 abutting one end of the tobacco rod 41 and joined thereto by a tipping wrapper 42 which overlies the join between the tobacco rod 41 and the filter rod 35. In the exemplary smoking article 40, ventilation holes 43 are provided to allow ambient air to be drawn into the filter rod 35 for increased ventilation as a user draws on the smoking article 40 in use. The ventilation holes 43 may extend though the plug wrap 38 of the filter rod 35 to allow ambient air to pass into the interior of the filter rod 35. Also in the exemplary smoking article 40, the inner core 36 and outer core 37 are visible at the end of the smoking article 40. This can provide a visual indicator to a consumer of the type of smoking article 40 and its associated filter performance and/or flavour.

In an embodiment of the invention, the second filter tow material 34 may include a smoke modifying material and may comprise, for example, a granular material such as flavourant or activated charcoal, which may be entrained in a carrier material, for example, entrained in cellulose acetate tow. Furthermore, the second filter tow material 34 may include an entrained flavourant. The flavourant may be provided as a solid particulate material such as flavourant granules, or may be provided as a liquid absorbed into a carrier material such as cellulose acetate tow.

The second filter tow material 34 being of a different composition to the first filter material 33 provides the inner core 36 with a different filtering characteristic to the surrounding outer core layer 37. For example, the inner core 36 may have a greater draw resistance than the outer core 37. The relative draw resistance of the inner core 36 and outer core 37 may be chosen to control the amount of smoke that, in use, is drawn through each part of the filter rod 35. For example, if the outer core 37 has a lower draw resistance than the inner core 36, a larger proportion of the smoke stream may flow through the outer core 37 than through the inner core 36. This can help limit the extent to which, as in conventional single-material filter rods, smoke flow tends to be greater towards the centre of the filter rod 35. This may even out the smoke flow through the filter rod 35 across the cross-section thereof. This may help to avoid localised discolouration of the end of the filter rod towards the centre of the filter rod 35·

The type and composition of the first and second filter tow materials 33, 34 may be selected to control, for example, the amount of smoke filtration that occurs, the flavourant that may be entrained in the smoke stream, or the proportion of the smoke stream that passes over activated charcoal granules. An increased level of plasticiser and hardening of the inner core 36 can give an increased draw resistance to the inner core 36 than that of the outer core 37. In an exemplary embodiment, the inner core 36 may comprise cellulose acetate with 10 - 20% plasticiser by weight, and the surrounding outer core layer 37 may comprise cellulose acetate with plasticiser in 3 - 8% by weight.

The inner core 36 being hardened provides smoking articles 40 with structural strength during smoking by a consumer. This can enable a certain "give" to the filter when in the mouth of the user, but also help avoid significant deformation of the filter during smoking.

In a further embodiment of the invention, one of the first or second filter tow materials 33_> 34 rnay be coloured and thereby may contrast with the other filter tow material.

This may provide a user with a visual indicator of the filter and/or flavour properties of the filter rod 35. For example, a filter tow material 33, 34 with a menthol flavour may be coloured green. Furthermore, a range of smoking articles may be provided that offer a range of smoking properties, for example differing filtering properties of flavour types or strengths. The inner core 36 and/or outer core 37 of the filter rods 35 of such various different smoking articles may be coloured in different shades of a particular colour, or different colours, to indicate said different properties.

In the smoking article 40 described above, a single discrete filter rod 35 is provided abutting the tobacco rod 41 and so the inner core 36 and outer core 37 of the filter rod 35 are visible at the mouth-end of the smoking article 40. The may provide the advantages described above. However, alternative embodiments of smoking articles are envisaged incorporating the above-described filters. Such smoking articles may include multi-segment filters. A second embodiment of smoking article 50 is shown in cross-section in Figure 5. Like features with the first embodiment of smoking article 40 retain the same reference numerals. The smoking article 50 of the second embodiment comprises a multi-segment filter 51 which comprises a first filter segment 35 as per the filter rod 35 described above, and a second filter segment 52 adjacent the first filter segment 35. The second filter segment 52 comprises a plug of a material such as cellulose acetate, preferably without an entrained particulate additive or core of different filter material.

A plug wrap 53 extends around the first and second filter segments 35, 52. The filter 51 is joined to a tobacco rod 41 by a tipping wrapper 42. The filter 51 is arranged such that the second filter segment 52 is disposed at the mouth-end of the smoking article, and the first filter segment 35 is disposed between the second filter segment 52 and the tobacco rod 41. The smoking article 50 of the second embodiment may be

advantageous in the case where a filter material 33, 34 of the first filter segment 35 comprises a particulate material as described above, for example, charcoal granules entrained in cellulose acetate tow. In such case, the second filter segment 52 prevents the particulate material from coming out of the first filter segment 35 and into a user's mouth when a user draws on the smoking article 50 in use. It may also provide the mouth-end of the smoking article 50 with a conventional appearance, namely a filter end with a plain end face of continuous filter material. This may be beneficial to enable provision of improved filtering, tactile and/ or flavour delivery functions using a dual core filter as described above, without presenting the consumer with a visually different smoking article to that of their regular preferred smoking articles. An advantageous configuration of the apparatus 10 of the invention comprises the outer duct 17 tapering to narrow along at least part of its length. That is, the distance between the outer surface of the inner duct 11 and the inner surface of the outer duct 17 reduces along at least a part of the length of the outer duct 17 in a conveyance direction of the second filter tow material 34. This helps compress and at least partially form the second filter tow material 34 into the hollow tubular configuration before being provided around the inner core 36. An advantageous configuration of the apparatus 10 and method of the invention, and filter rods 35 formed thereby, is that the inner core 36 and outer core 37 are each formed of a generally homogenous material although each are separate materials. That is, the material of the inner core 36 is not mixed or blended with the material of the outer core 37 and a clear boundary exists between them. As well as providing a distinctive and clean appearance, this also allows accurate control of the filtering characteristics and performance of the filter rods 35 of the invention.

The apparatus 10 and methods of the invention described above comprise dry steam at around 170 degrees Celsius being supplied to the inner duct 11. However, the invention is not limited to this specific temperature and the temperature of the dry steam may vary within the scope of the invention. For example, between 100 - 200 degrees Celsius, and may be between 120 - 190 degrees Celsius, and may be between 150 - 180 degrees Celsius. Furthermore, the temperature of the steam may be selected proportional to the amount of plasticiser entrained in the first filter tow material 33 and/ or also the conveyance speed of the first filter tow material 33 through the inner duct 11.

In an advantageous configuration of the apparatus 10 of the invention, the inner and outer ducts 11, 17 are elongate and comprise respective central axes, and the inner and outer ducts 11, 17 are co-axial. This may advantageously enable formation of symmetrical and uniform filter rods 35.

The apparatus 10 of the invention described above includes the inner duct 11 being disposed within the outer duct 17. It is to be understood that "disposed within" is intended to encompass the inner duct 11 being both entirely disposed within the outer duct 17 and at least partially disposed within the outer duct 17, such that one or both ends of the inner duct 11 may extend beyond the corresponding end of the outer duct 17-

The apparatus 10 of the invention described above includes the outlet 13 of the inner duct 11 being disposed within the outer duct 17. This advantageously allows the inner core 36 to be expelled into the outer core 37 whilst still constrained within the bore 20 of the outer duct 17. However, the invention is not intended to be limited to this configuration and the outlet 13 of the inner duct 11 may extend beyond the outlet end 19 of the outer duct 17. This may advantageously allow a greater time for the first filter material 33 to be contained within the inner duct 11 to be heated by the steam S, before the first filter material 33 is expelled out of the outlet 13 of the inner duct 11.

In the apparatus 10 and method of the embodiments described above, the steam S is exclusively provided to the inner duct 11. That is, the steam S is only provided and released into the interior bore 14 of the inner duct 11, and is not provided to be freely released within the bore 20 of the outer duct 17. Thereby, the steam S is only able to permeate the first filter material 33 and is not able to permeate the second filter material 34. This helps ensure that the second filter material 34 remains of a softer texture than the first filter material 33 in the finished filter rod 35.

In an embodiment of the invention (not shown), the inner duct 11 may include a thermally insulating layer or coating on at least part of its outer surface. This may advantageously help prevent heat supplied to the inner duct by the steam from permeating to the outer duct and to the second filter material 34 conveyed

therethrough, which may help ensure that the second filter material 34 remains of a softer texture than the first filter material 33 in the finished filter rod 35.

In the apparatus 10 shown, the steam feed pipes 16 extend through the bore 20 of the outer duct 17 to reach the inner duct 11. However, the invention is not intended to be limited to this configuration and the steam pipes 16 may alternatively be provided along the outer surface of the inner duct 11 and enter via the inlet 18 of the outer duct 17 so as not to extend across a substantial portion of the cross-section of the bore 20 of the outer duct 17. The apparatus 10 shown and described includes a plurality of steam inlets 16a and steam pipes 16, although the apparatus of the invention may include only one steam inlet 16a and steam feed pipe 16. The apparatus 10 shown and described comprises a circular outlet 13 of the inner duct 11 such that the inner core 36 is formed with a circular cross-section. However, the invention is not intended to be limited to this configuration and the outlet 13 of the inner duct 11 may be of a different shape, for example square, triangular, star-shaped, oval or any other shape, so as to provide the inner core 36 with a corresponding cross- sectional shape.

It is intended within the scope of the invention that the outlet 13 of the inner duct 11 may include a die with an outlet aperture formed therein, to define the shape of the extruded inner core 36. Such an embodiment is schematically illustrated in Figure 6, which shows in cross-section an end portion of an alternative configuration of inner duct 11. The inner duct 11 includes, at the outlet 13, a threaded section 61 on the inside surface of the bore 14. A die 62 with a threaded outer surface is secured in the outlet 13 of the inner duct 11. The die 62 includes an outlet aperture 63 through which the first filter material 33 is extruded to form the inner core 36. The die 62 may therefore be removable from the inner duct 11, to allow for maintenance or replacement, and also to allow the die 62 to be interchanged with other dies which may have a difference shaped or sized outlet aperture 63 to enable production of difference configurations of filter rod 35. However, the invention may encompass an inner duct 11 which comprises an integrally formed die at its outlet 13.

In the second embodiment of smoking article 50 described above, the multi-segment filter 51 includes a plug wrap 53 extending around the first and second filter segments 35, 52. This advantageously aids manufacturing as the multi-segment filter 51 maybe assembled prior to a separate step in which it is joined to a tobacco rod 41 to make the smoking article 50. Also, multiple-lengths of multi-segment filters maybe produced (e.g. 2-up, 4-up or 6-up rods) with the filter segments joined by a plug wrap, before being combined with tobacco rods in a separate assembly step to produce smoking articles. However, the invention is not intended to be limited to such a configuration of smoking article, and it is intended that the first and second filter segments 35, 52 may be axially aligned and joined together and to the tobacco rod 41 by the tipping wrapper 42 alone, without also including a plug wrap. This latter configuration may advantageously reduce the number of smoking article assembly steps by the tobacco rod 41, and first and second filter segments 35, 52 all being combined together with a tipping wrapper in a single assembly process. As used herein, the term "smoking article" includes smokeable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products and tobacco heating products, and other nicotine delivery product such as aerosol generation devices including e-cigarettes. The smoking article may be provided with a filter for the gaseous flow drawn by the smoker. In embodiments intended for use with heat-not-burn products and other nicotine delivery products, reference in the description above to "smoke" and "smoke modifying material" should be construed as encompassing other aerosols and inhalants other than smoke and the products of combustion of a material.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for superior filters, and apparatuses and methods for manufacture of filters. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/ or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/ or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims

A filter rod for a smoking article comprising an extruded hardened inner core of a first filter material, an outer core of a second filter material surrounding the inner core and of a softer texture than the first filter material, and a plug wrap around the outer core.

A filter rod according to claim l wherein the first filter material comprises cellulose acetate tow which is hardened with a plasticiser.

A filter rod according to claim l or claim 2 wherein the second filter material comprises cellulose acetate.

A filter rod according to claim 3 wherein the first and second filter materials both comprise cellulose acetate tow, and wherein the amount of plasticiser entrained in the first filter material is greater than any amount of plasticiser that maybe entrained in the second filter material.

A filter rod according to any preceding claim wherein the first filter material and/ or the second filter material comprises a granular aerosol modifying material.

A filter for a smoking article comprising a filter rod according to any preceding claim, and a second filter segment axially aligned with the filter rod and joined thereto by a plug wrap around the filter rod and second filter segment.

A smoking article comprising a tobacco rod and a filter rod or filter according to any preceding claim joined to one end of the tobacco rod.

An apparatus for manufacturing a dual core filter rod for smoking articles, the apparatus comprising:

an inner duct having an inlet to receive a first filter material including a plasticiser and an outlet through which the first filter material is expelled; an outer duct having an inlet to receive a second filter material and an outlet through which the second filter material is expelled; wherein the inner duct is disposed within the outer duct to enable formation of a continuous body of filter material comprising an inner core of the first filter material surrounded by an outer core of the second filter material; and

a wrapping station disposed proximate the outlets of the inner and outer ducts to provide a plug wrap around the continuous body of filter material; wherein the inner duct includes at least one steam inlet for the introduction of steam into the inner duct to heat the first filter tow material as it is conveyed through the inner duct to form a hardened inner core.

An apparatus according to claim 8 wherein the outer duct tapers between the inlet and the outlet.

An apparatus according to claim 8 or claim 9 wherein the inner duct tapers between the inlet and the outlet.

An apparatus according to any of claims 8 to 10 wherein the outlet of the inner duct is disposed within the outer duct.

An apparatus according to claim 11 when dependent on claim 9, wherein the outer duct comprises first and second sections, wherein the first section tapers from the inlet to the second section, and the second section is of constant cross-section, and wherein the outlet of the inner duct is disposed within the second section of the outer duct.

An apparatus according to any of claims 8 to 12 wherein the inner duct is disposed coaxially with the outer duct.

An apparatus according to any of claims 8 to 13 wherein the steam inlet is provided in a side wall of the inner duct between the inlet and outlet.

An apparatus according to any of claims 8 to 14 comprising a steam supply pipe connected to the at least one steam inlet and configured to supply steam directly and exclusively into the inner duct through the steam inlet. An apparatus according to any of claims 8 to 15 wherein the outlet of the inner duct comprises a removable die having an outlet aperture through which the first filter material is expelled.

An apparatus according to any of claims 8 to 16 wherein at least a portion of an outer surface of the inner duct is provided with a thermally insulating layer.

An apparatus according to any of claims 8 to 17 wherein the wrapping station comprises a spool of a web of plug wrap, a tapering guide duct to receive the continuous and a continuous driven belt extending through the tapering guide duct to convey the plug wrap web through the tapering guide duct so that the continuous body of filter material is fed onto the web of plug wrap and the web of plug wrap is wrapped around the core and surrounding layer as it is conveyed through the tapering guide duct.

An apparatus according to any of claims 8 to 18 further comprising a cutting station configured to cut the continuous wrapped filter rod into discrete filter rods.

A method of manufacturing a dual core filter rod for smoking articles, the method comprising:

feeding a first filter material including a plasticiser into an inlet of an inner duct and conveying the first filter material through the inner duct and out of an outlet of the inner duct;

feeding a second filter material into an inlet of an outer duct and conveying the second filter material through the outer duct and out of an outlet of the outer duct;

wherein the inner duct is disposed within the outer duct so that a continuous body of filter material is formed comprising an inner core of the first filter material surrounded by an outer core of the second filter material; introducing steam into the inner duct through at least one steam inlet formed therein to heat the first filter tow material as it is conveyed through the inner duct to at least partially cure the plasticiser to form a hardened inner core; and

providing a plug wrap around the continuous body of filter material at a wrapping station disposed proximate the outlets of the inner and outer ducts.

A method according to claim 20 wherein the inner duct tapers between the inlet and the outlet, the method comprising compressing the first filter material to form the inner core as it is conveyed through the inner duct.

A method according to claim 20 or claim 21 wherein the outer duct tapers between the inlet and the outlet, the method comprising compressing the second filter material to form the outer core as it is conveyed through the outer duct.

A method according to any of claims 20 to 22 comprising expelling the first filter material out of the outlet of the inner duct within the outer duct.

A method according to any of claims 20 to 23 comprising feeding steam via the steam inlet through a side wall of the inner duct between the inlet and outlet.

A method according to any of claims 20 to 24 comprising feeding steam via a steam supply pipe connected to the at least one steam inlet directly and exclusively into the inner duct.

A method according to any of claims 20 to 25 comprising providing cellulose acetate tow impregnated with plasticiser as the first filter material.

A method according to any of claims 20 to 26 comprising providing a cellulose acetate tow as the second filter material.

A method according to any of claims 20 to 27 comprising heating the first filter material within the inner duct with steam at between 100 - 200 degrees Celsius.

A method according to any of claims 20 to 28 further comprising cutting the continuous wrapped filter rod into discrete filter rods.