阅读说明：本技术 烟草烟雾过滤器 (Tobacco smoke filter ) 是由 艾哈迈德·法希胡尔·利桑 罗伊·阿林加兰 巴功·乔恭叻 于 2013-07-31 设计创作，主要内容包括：本发明涉及烟草烟雾过滤器或过滤器元件、过滤器香烟、或多节棒,包含围绕烟草烟雾过滤材料的下游热成型芯接合的硬质外包装物和与其纵向对齐的另外的芯；下游热成型芯具有异形的外表面,其与硬质外包装物一起限定了至少一个纵向延伸的通道,所述通道沿下游芯的长度延伸。本发明允许改善在过滤器中缺少空气和烟雾的混合而引起的所谓“空气和烟雾”效应导致的较差的口感。(The present invention relates to a tobacco smoke filter or filter element, filter cigarette, or multi-segment rod comprising a stiff outer wrapper joined around a downstream thermoformed core of tobacco smoke filtering material and a further core longitudinally aligned therewith; the downstream thermoformed core has a contoured outer surface that, together with the stiff outer wrapper, defines at least one longitudinally extending channel extending along the length of the downstream core. The invention allows to improve the poor taste sensation caused by the so-called "air and smoke" effect due to the lack of mixing of air and smoke in the filter.)

1. A tobacco smoke filter or filter element comprising a stiff outer wrapper engaged around a downstream thermoformed core of tobacco smoke filtering material, and a further core longitudinally aligned therewith; the downstream thermoformed core has a contoured outer surface that defines with the hard outer wrapper at least one longitudinally extending channel extending along the length of the downstream core.

2. A tobacco smoke filter or filter element according to claim 1 wherein the stiff outer wrapper comprises a stiff paper, for example a stiff plug wrap.

3. A tobacco smoke filter or filter element according to claim 1 or claim 2 wherein the plug wrap paper is a paper of basis weight about 80 to 120gsm, or a paper of basis weight 30 to 80gsm, to which an additive is applied to stiffen it, or which is processed or formulated to produce a stiffer structure than conventional plug wrap paper.

4. A tobacco smoke filter or filter element according to any preceding claim wherein the further core comprises a core wrapper engaged around the further core.

5. A tobacco smoke filter or filter element according to any preceding claim comprising one or more additional cores longitudinally aligned with the downstream thermoformed and further cores.

6. A tobacco smoke filter or filter element according to any preceding claim wherein the profiled outer surface of the downstream core together with the stiff outer wrapper defines from 1 to 16 longitudinally extending channels extending along the length of the core.

7. A tobacco smoke filter or filter element according to any preceding claim wherein the profiled outer surface of the downstream core together with the stiff outer wrapper defines 4 to 10 longitudinally extending channels extending along the length of the core.

8. A tobacco smoke filter element comprising a thermoformed core of tobacco smoke filtering material having a profiled outer surface comprising at least one longitudinally extending groove extending along the length of the thermoformed core.

9. A filter cigarette comprising a filter according to any one of the preceding claims or a filter comprising a filter element according to any one of the preceding claims, the filter being attached to a wrapped tobacco rod.

10. A multi-linked rod comprising a plurality of filters or filter elements according to claims 1 to 8 integrally connected end-to-end in mirror image relationship.

Technical Field

The present invention relates to tobacco smoke filters and filter elements, for example for smoking articles such as cigarettes.

Background

So-called "Actron" type tobacco smoke filters are well known (see for example US 4256122). These include a core of thermoformed cellulose acetate material that includes partial lengths of outer channels, and an imperforate core wrapper that conforms to the profile of the channels. The filter includes a ventilated outer wrapper which allows ventilation air to enter the outer channel and flow along the outer channel into the mouth of the smoker along with the smoke drawn through the cellulose acetate material wick. The non-porous core wrapper prevents the ingress of ventilation air into the cellulose acetate core so there is no mixing of air and smoke in the filter. These filters tend to press the ventilated outer wrapper into the channel (e.g., by the mouth of a smoker during cigarette manufacture and/or in use). Furthermore, the so-called "air and smoke" effect caused by the lack of mixing of air and smoke in the filter may result in a poor mouth feel.

Other filters with fluted wraps or contours are also subject to compression during processing and handling.

There is a need for a tobacco smoke filter that does not suffer from these disadvantages.

Disclosure of Invention

According to the present invention there is provided a tobacco smoke filter (or filter element) comprising a stiff outer wrapper engaged around a downstream (longitudinally extending) thermoformed core of tobacco smoke filtering material, and a further (longitudinally extending, e.g. substantially cylindrical) core (of tobacco smoke filtering material) longitudinally aligned with the stiff outer wrapper; the downstream thermoformed core has a profiled (e.g. grooved, e.g. corrugated) outer surface which together with (the inner surface of) the stiff outer wrapper defines at least one (e.g. clad) longitudinally extending channel which extends (e.g. continuously) along the (full) length of the downstream core. The further core of tobacco smoke filtering material is longitudinally aligned with the downstream thermoformed core of tobacco smoke filtering material. The further core of tobacco smoke filtering material is upstream of the thermoformed core downstream of the tobacco smoke filtering material. Preferably the (downstream end of the) further core of tobacco smoke filtering material is longitudinally aligned with and abuts the (upstream end of the) downstream thermoformed core of tobacco smoke filtering material.

In this context, the term "downstream" means towards the end of the filter/filter element/filter cigarette closest to the mouth of the smoker of the filter cigarette (e.g. when the filter/filter element is attached to the tobacco housing in the filter cigarette). The term "upstream" means towards the end of the filter/filter element closest to the tobacco housing of the filter cigarette (e.g. when the filter/filter element is attached to the tobacco housing in a filter cigarette).

As used herein, the term "thermoformed core" means a core that is shaped or molded into a cohesive, self-supporting core by the action of heat on the tobacco smoke filtering material (and optionally other ingredients such as plasticizers).

Preferably, the rigid outer wrapper comprises a stiff paper, such as a rigid plug wrap. The stiff outer wrapper may be paper (e.g., formed paper) having a basis weight of about 80 to 120 gsm. The stiff outer wrapper may be a lighter weight, such as paper having a basis weight of 30 to 80gsm (e.g., plug wrap), to which an additive is applied to stiffen it, or which is processed or formulated to produce a stiffer structure than conventional plug wrap, as is well known in the art. Hard papers, such as hard formed paper, are well known in the art.

Preferably, the downstream thermoformed core does not include other wrappers (e.g., air impermeable wrappers) conforming to (e.g., adhering to) the contour of its contoured outer surface. In other words, there is preferably no other wrapper between the profiled outer surface of the downstream core and the inner surface of the stiff outer wrapper. Preferably, the downstream thermoformed core is a core comprising cohesive, adhesive, (smoke permeable) material. The term cohesive herein means self-supporting; the cohesive bonding thermoformed core material retains its shape and forming surface without the need for a forming wrapper (to retain its shape).

The additional core may comprise a core wrapper engaged around (e.g. longitudinally extending, generally cylindrical) the additional core. The wrapper may be paper, such as plug wrap.

The filter or filter element may optionally comprise one or more additional (e.g. longitudinally extending, generally cylindrical) cores (of tobacco smoke filtering material, for example) longitudinally aligned with the downstream thermoformed core and the further core. The (or each) additional core may comprise a core wrapper engaged around (e.g. longitudinally extending, generally cylindrical) the additional core. The wrapper may be paper, such as plug wrap.

The profiled (e.g. corrugated) outer surface of the downstream (thermoformed) core may together with the (inner surface of the) stiff outer wrapper define (e.g. cladded) longitudinally extending channels (e.g. one to sixteen longitudinally extending channels, preferably 4 to 10 channels, e.g. 5 to 10 channels) which extend continuously along the downstream thermoformed core (along the full length of the core). It should be understood that the above exemplified number of channels is preferred for a filter having a circumference of about 24.5 mm.

Applicants have found that the combination of a shaped (e.g., corrugated or fluted) thermoformed downstream core with a stiff outer wrapper (e.g., stiff plug wrap) gives a better end boundary than previous similar products because the flutes (channels) are not crushed or distorted during subsequent processing and use of the filter or filter cigarette. The thermoformed core does not require an additional wrapper (e.g., an air impermeable wrapper) conforming to the contour of its contoured outer surface, which can result in improved smoking quality (e.g., by reducing or eliminating the "air and smoke" effect) because ventilation air can enter the downstream core and mix with the smoke.

The downstream end of the stiff outer wrapper may extend beyond its downstream end around the engaged (downstream thermoformed) core to define a (e.g. substantially tubular) cavity at the downstream end of the filter or filter element. The radially inner face of the stiff outer wrapper extending beyond its downstream end around the engaged core may (e.g. together with the downstream end of the downstream thermoformed core) define a cavity or recess, e.g. a generally tubular cavity/recess, at the downstream end of the filter or filter element. Thus, the filter or filter element may be a notch filter/filter element.

One or more of the downstream thermoformed core, the further core wrapper (if present), the stiff outer wrapper, the or each additional core (if present) and the or each additional core wrapper (if present) may optionally be coloured or dyed (for example with a suitable dye or pigment, preferably those approved by regulatory authorities for food contact applications). The additional core may be of a contrasting color or have a contrasting color wrapper for the color of the downstream thermoformed core. The dye or pigment may preferably be any colour which contrasts with the (e.g. white) thermoformed core downstream of the tobacco smoke filtering material, e.g. green, blue, red, orange etc. Each of the downstream thermoformed core, the additional core and the additional core (if present) may be the same color as the other cores or a different color. The additional and/or additional cores may comprise a coloured or dyed wrapper (e.g. coloured with a suitable dye or pigment, preferably those approved by regulatory authorities for food contact applications).

In one example, the further core comprises tobacco smoke filtering material coloured or dyed red (e.g. with a suitable dye or pigment, preferably those approved by regulatory authorities for food contact applications), and the downstream thermoformed core comprises white tobacco smoke filtering material (e.g. cellulose acetate). It will be appreciated that in this embodiment, when the downstream end of the downstream core is viewed "end-to-end" along the longitudinal axis of the filter/element, the red color of the additional core will contrast with the upstream end of the channel in the downstream thermoformed core and thus be visible. This contrast provides a unique appearance to the product filter, element or filter rod, which is useful for anti-counterfeiting purposes.

Thus, the unique end appearance provided by the downstream thermoformed core and the downstream end of the rigid outer wrapper (optionally in combination with a colored rigid outer wrapper, a colored additional core, a notched downstream thermoformed core, etc.) is robust (due to the strength of the wrapper and the forming surface) and retains useful original signs and anti-counterfeiting measures during subsequent manufacture and smoking of, for example, a filter cigarette.

The downstream core of thermoformed tobacco smoke filtering material may be made of any thermoformed tobacco smoke filtering material. The filter material may be, for example, natural or synthetic filamentary tow, for example filamentary tow of cotton or plastics such as polyethylene or polypropylene, cellulose acetate filamentary tow, and extruded material (e.g. starch, synthetic foam, extruded foam). Preferably, the downstream thermoformed core of tobacco smoke filtering material comprises cellulose acetate, for example extruded filamentary cellulose acetate. The downstream thermoformed core of tobacco smoke filtering material may comprise cellulose acetate tow, optionally including a plasticizer (e.g. triacetin). The downstream thermoformed core may be formed by: a stream of tobacco smoke filtering material (e.g. cellulose acetate tow, optionally including or carrying a plasticiser) is continuously advanced (e.g. continuously drawn and/or gathered) through a forming die of suitable non-circular cross-section which forms a core having a profiled outer surface, (optionally) heat treating the advanced core as and/or shortly after it is formed (optionally with a subsequent cooling step) -for example by a process similar to that disclosed in WO 2011/148130. The heat treatment (and optional cooling) can activate the plasticizer to form the filter material into a cohesive, adhesive, smoke permeable downstream thermoformed core having a contoured (e.g., grooved, e.g., contoured) outer surface.

The additional core and additional core (if present) may comprise tobacco smoke filtering material. The tobacco smoke filtering materials used for the core may be the same or different. The tobacco smoke filtering material may be, for example, any of those materials conventionally used in the manufacture of tobacco smoke filters (typically filamentary, fibrous, web or extruded). The filter material may be natural or synthetic filamentary tow, for example of cotton or plastics such as polyethylene or polypropylene, or cellulose acetate filamentary tow. It may be, for example, natural or synthetic staple fibres, cotton linters, web materials such as paper (usually creped) and (for example synthetic) nonwovens, and extruded materials (for example starch, synthetic foams, extruded foams). The filter material of the further core and/or the additional core may be cellulose acetate.

As mentioned above, the further (e.g. longitudinally extending, e.g. generally cylindrical) core may comprise tobacco smoke filtering material. Preferably the tobacco smoke filtering material is cellulose acetate. The further (e.g. longitudinally extending, e.g. substantially cylindrical) core may comprise a further core wrapper, e.g. an impermeable plug wrap, engaged around the core. The additional core may be a non-wound, generally cylindrical cellulose acetate core, such as, for example, a non-wound acetate (NWA) filter segment, as is known in the art.

The additional core and, if present, the additional core may comprise additives, for example particulate additives, such as activated carbon.

The tobacco smoke filter or filter element may include (with) a flavouring agent. One or more of the downstream thermoformed core, the further core wrapper (if present), the stiff outer wrapper, the or each additional core (if present) and the or each additional core wrapper (if present) may comprise (with) a flavouring agent. The flavouring agent may be any known flavouring agent for tobacco smoke filters or filter elements. For example, the flavoring agent may be menthol, spearmint, peppermint, nutmeg, cinnamon, clove, lemon, chocolate, peach, strawberry, vanilla, and the like. The agent may comprise nicotine or a salt or derivative thereof. Preferably the flavouring agent is menthol. If more than one core/wrapper includes a flavoring agent, the flavoring agents may be the same or different.

The length of the tobacco smoke filter or filter element may be 12 to 40mm, for example 17 to 35mm, for example 20 to 30 mm.

The circumference of the tobacco smoke filter (or filter element) may be 14 to 28mm, for example 16 to 26mm, for example 16 to 17mm or 24 to 25 mm.

In a filter cigarette according to the invention, the filter of the invention (or a filter comprising the filter element of the invention) is attached to the wrapped tobacco rod at the end of the filter facing the tobacco (the upstream end). The filter may be attached to the wrapped tobacco rod by a ring tipping (which engages around only the adjacent ends of the (wrapped) filter and rod, leaving most of the filter wrapper exposed). The filter may be attached by a full tipping overwrap (which engages around the full filter length and the adjacent end of the tobacco rod).

Preferably the rigid outer wrapper comprises a ventilation, e.g. a ventilation zone. The rigid outer package may comprise a venting area comprising at least one ring-shaped or annular venting hole, around the circumference of the filter/filter element. These vents may be aligned with any section that may be present in the filter. The hardened outer wrapper may comprise one or more ventilation zones aligned with the (or each) channel defined between the profiled (e.g. grooved, e.g. corrugated) outer surface of the thermoformed core and the (inner surface of the) hardened outer wrapper. The inclusion of ventilation may result in further improved smoking quality (e.g. by further reducing or eliminating the "air and smoke" effect, as ventilation air may more readily enter the downstream wick).

Filters, filter elements or filter cigarettes according to the invention may be ventilated by methods known in the art, for example by using a pre-perforated or breathable rigid outer wrapper, and/or laser perforating the rigid outer wrapper and the tipping overwrap (if present). Similarly, a ventilated full tipping overwrap may be inherently air permeable, or provided with ventilation holes, and in ventilated products where both a stiff overwrap and a tipping overwrap are present, the ventilation area through the overwrap is generally (and preferably) aligned with the ventilation area through the plug wrap. The ventilation holes through the rigid outer wrapper, or through the tipping outer wrapper, or both, may be made by laser perforation during filter or filter cigarette production, as is well known in the art.

The downstream thermoforming core may define one or more other channels or apertures extending longitudinally through the downstream thermoforming core. The other channels or holes may extend, for example, from the downstream end through the downstream thermoformed core. Other channels or holes may extend, for example, from the downstream end through the downstream thermoformed core to the upstream end. The (or each) other channel or aperture may have a cross-section of any shape, for example a circular, oval, star, heart, trilobal, pentagonal, castellated or logo-shaped cross-section. Preferably the (or each) other channel or aperture has a symmetrical (shape symmetrical) cross-section.

The downstream thermoforming core may define a single channel or hole extending longitudinally through the downstream thermoforming core. The downstream thermoformed core may define more than one (e.g. narrow) channel or aperture rather than a single (wider) channel or aperture. The downstream thermoformed core may define a channel or aperture that preferably extends through the center of the downstream thermoformed core (i.e., along the central axis of the core). Preferably there is at least 1.2mm of thermoformable material between (the periphery of) one or more of the other channels or apertures and the portion of the profiled outer surface nearest to (the periphery of) the other channels or apertures.

According to the present invention, in another aspect, there is provided a tobacco smoke filter element comprising a (longitudinally extending) thermoformed core of tobacco smoke filtering material having a profiled outer surface comprising at least one longitudinally extending groove, the groove extending (e.g. continuously) along the (full) length of the thermoformed core. The profiled (e.g. corrugated) outer surface of the (thermoformed) core may comprise from one to sixteen longitudinally extending grooves (preferably from 4 to 10 grooves, for example from 5 to 10 grooves) which extend (e.g. continuously) along the thermoformed core (along its full length).

The filter element may further comprise a stiff outer wrapper engaged around the (longitudinally extending) thermoformed core of tobacco smoke filtering material. The profiled (e.g. grooved, e.g. corrugated) outer surface may thus define together with the (inner surface of the) hard outer wrapper at least one (e.g. cladded) longitudinally extending channel (e.g. continuously) extending along the (full) length of the core (formed by the hard outer wrapper cladding the grooves in the outer surface of the core).

Preferably, the rigid outer wrapper comprises a rigid paper, such as a rigid plug wrap. The stiff outer wrapper may be paper (e.g., formed paper) having a basis weight of about 80 to 120 gsm. The stiff outer wrapper may be a relatively light weight, such as paper having a basis weight of 30 to 80gsm (e.g., formed paper), to which an additive is applied to stiffen it, as is well known in the art. Hard papers, such as hard plug wrap, are well known in the art.

Preferably, the thermoformed core does not include other wrappers (e.g., air impermeable wrappers) that conform to (e.g., adhere to) the contour of its contoured outer surface. In other words there is preferably no other wrapper between the profiled outer surface of the core and the inner surface of the stiff outer wrapper (if present). Preferably, the thermoformed core is a core comprising a cohesive, adhesive, (smoke permeable) material, such as cellulose acetate. The term cohesive herein means self-supporting; the cohesive bonding thermoformed core material retains its shape and forming surface without the need for a sizing wrapper (to retain its shape). Suitable materials for the thermoformed core are as described above with respect to the downstream thermoformed core.

The total cross-sectional area of the longitudinally extending channels/grooves may amount to between 3% and 22%, preferably at least 5%, more preferably between 6% and 18% of the total cross-sectional area of the (downstream) thermoformed core of the filter. Careful control of the number and/or depth of the channels (e.g., as determined by the thermoforming process used to make the downstream core) can give improved filtration performance and/or sensory characteristics. This can be achieved by: increasing the depth of the corrugations preferably increases the surface area of the corrugations together, optionally increasing the wave spacing together-i.e. widening the corrugations and reducing their number. For example, a filter according to the present invention may have five channels with a depth of about 0.75mm and a wave spacing of about 2.0 mm.

According to the present invention, in another aspect, there is provided a multi-segmented rod comprising a plurality (e.g., 2, 4, 6, etc.) of filters (or filter elements) as described above and/or herein connected end-to-end in mirror image relationship as a whole.

Drawings

The invention will now be described with reference to the following examples and figures, in which figure 1 schematically illustrates a filter according to a first embodiment of the invention, and figure 2 shows a downstream end view of a filter according to another embodiment of the invention.

Detailed Description

Figure 1 shows a tobacco smoke filter 1 of length 30mm and circumference about 25mm comprising a stiff outer wrapper 2 (shown in dotted lines) made of stiff plug wrap paper having a basis weight of 100 gsm. The stiff outer wrapper being engaged around a downstream longitudinally extending thermoformed core 3 of tobacco smoke filtering material of length 15 mm; and a longitudinally extending, generally cylindrical further core 4 of tobacco smoke filtering material, also 15mm in length. The further core 4 is longitudinally aligned with the thermoformed core 3 and the downstream end of the further core 4 abuts the upstream end of the downstream thermoformed core of tobacco smoke filtering material. The hard outer wrapper includes a vent (not shown).

Downstream thermoformed core 3 is formed from cellulose acetate tow to which a triacetin plasticizer is applied. The core 3 is formed into cores of various lengths by the following method: a stream of tobacco smoke made from cellulose acetate tow with plasticiser is continuously drawn and/or gathered through a sizing die to form advancing lengths of core having a profiled outer surface, and the advancing lengths of core are heat treated (with a subsequent cooling step) as they are formed and/or shortly thereafter by a process similar to that disclosed in WO 2011/148130. The heat treatment and cooling activates the plasticizer to form the cellulose acetate material into lengths of cohesive, adhesive, smoke permeable downstream thermoformed core having a contoured (e.g., grooved, e.g., corrugated) outer surface. The cores of various lengths are then cut into individual cores 3 by methods well known in the art during filter or cigarette formation.

The downstream thermoformed core 3 has a profiled outer surface comprising four longitudinally extending channels 5. Each slot 5 defines, together with the inner surface of the stiff outer wrapper, a longitudinally extending channel (which is enveloped by wrapper 2) which extends continuously along the entire length of the downstream core 3.

The additional core 4 is a non-wound, generally cylindrical cellulose acetate core, such as, for example, a non-wound acetate (NWA) filter segment, as is well known in the art.

It will be appreciated that a filter as shown in figure 1 may be made by methods well known in the art, for example by advancing a continuous stream of multiple filter rods (e.g. dual filter rods) of composition longitudinally (suitably aligned, e.g. with the dual component rods forming the downstream core 3 between the dual component rods forming the further core 4) to a packing assembly where a continuously advancing rigid overwrap is wrapped around the longitudinally advancing multiple filter rods of composition and secured (as is well known) by means of lap and adhesive seams. The wrapped longitudinally advancing assembled multi-filter rod stream is then suitably cut for further use by methods well known in the art.

The filter 1 is connected to the wrapped tobacco rod 6 with the upstream core 4 facing the tobacco. The filter 1 is attached to the wrapped tobacco rod 6 by a ring tipping by methods well known in the art [ which engages around only the adjacent ends of the (wrapped) filter and rod to expose a substantial portion of the rigid wrapper 2 ].

The applicant has found that the combination of a profiled thermoformed downstream core with a stiff outer wrapper gives a better end-boundary than previous similar products, since the wrapped channel is not squeezed or distorted during subsequent processing and use of the filter or filter cigarette; this is useful for anti-counterfeiting purposes. The thermoformed core is cohesive and self-supporting, and thus does not require additional wrappers (e.g., air impermeable wrappers) conforming to the contour of its contoured outer surface, which can result in improved smoking quality (e.g., by reducing or eliminating the "air and smoke" effect) because ventilation air can enter the downstream core through the ventilation and/or longitudinally extending channels.

In another embodiment (not shown), a tobacco smoke filter similar to that shown in figure 1 comprises another NWA core that is coloured or dyed red (e.g. with a suitable dye or pigment, those approved by regulatory authorities for food contact applications), with the downstream thermoformed core comprising white cellulose acetate (as in figure 1). It will be appreciated that in this embodiment, when the downstream end of the downstream core is viewed "end-to-end" along the longitudinal axis of the filter/element, the red color of the additional core will be contrasted with the upstream end of the longitudinally extending channels in the downstream thermoformed core and will therefore be visible. This contrast provides an enhanced unique appearance to the product filter, element or filter rod, useful for anti-counterfeiting purposes.

Fig. 2 shows a downstream end view of another embodiment of the present invention. In this embodiment, a tobacco smoke filter 10 of length 30mm and circumference around 25mm comprises a stiff outer wrapper 12 (shown in bold line) made of stiff plug wrap having a basis weight of 100 gsm. The stiff outer wrapper being engaged around a downstream longitudinally extending thermoformed core 13 of tobacco smoke filtering material of length 15 mm; and a longitudinally extending generally cylindrical further core of tobacco smoke filtering material, also 15mm in length (not shown). The further core is longitudinally aligned with the thermoformed core 13 and the downstream end of the further core abuts the upstream end of the downstream thermoformed core 13 of tobacco smoke filtering material. The hard outer wrapper includes a vent (not shown).

The downstream thermoformed core 13 has a profiled outer surface comprising four longitudinally extending grooves 15. Each slot 15 defines, together with the inner surface of the stiff outer wrapper, a longitudinally extending channel (which is enveloped by the wrapper 12) which extends continuously for the full length of the downstream core 13.

The downstream thermoformed core 13 defines another channel or aperture 17 of circular cross-section extending longitudinally through the downstream thermoformed core. The holes 17 extend through the downstream thermoformed core from the downstream end to the upstream end. As shown in fig. 2, the hole 17 extends through the center of the downstream thermoformed core (i.e., along the central axis of the core). As shown in fig. 2 (although not to equal scale), there is at least 1.2mm of thermoformable material between the periphery of the hole 13 and the nearest portion of the profiled outer surface of the core 13.

The downstream thermoformed core 13 is formed from cellulose acetate tow with triacetin plasticizer applied thereto in a manner similar to that used to form thermoformed core 3 of the embodiment of fig. 1.

An additional core (not shown) is a non-wound, generally cylindrical cellulose acetate core, such as, for example, a non-wound acetate (NWA) filter segment, as is known in the art.

The filter 10 may be attached to the wrapped tobacco rod with the upstream core facing the tobacco. The filter is attached to the wrapped tobacco rod 6 by a ring tipping arrangement by methods well known in the art which engages around only the adjacent ends of the (wrapped) filter and rod to expose a substantial portion of the rigid wrapper 2.

The embodiment of fig. 2 has a hole 17 with a circular cross-section. It should be understood that in other embodiments of the invention (not shown), the aperture may have a cross-section of any shape, such as a circular, oval, star, heart, trilobal, pentagonal, castellated, or logo-shaped cross-section. In other embodiments (not shown), the downstream thermoformed core may define more than one (e.g., narrow) aperture, rather than a single aperture.

The following corresponds to the original claims of the parent application:

1. a tobacco smoke filter or filter element comprising a stiff outer wrapper engaged around a downstream thermoformed core of tobacco smoke filtering material, and a further core longitudinally aligned therewith; the downstream thermoformed core has a contoured outer surface that defines with the hard outer wrapper at least one longitudinally extending channel extending along the length of the downstream core.

2. The tobacco smoke filter or filter element of item 1 wherein the stiff outer wrapper comprises a stiff paper, such as a stiff plug wrap.

3. A tobacco smoke filter or filter element according to item 1 or item 2 wherein the plug wrap paper is a paper of basis weight from about 80 to 120gsm, or a paper of basis weight from 30 to 80gsm, to which an additive is applied to stiffen it, or which is processed or formulated to produce a stiffer structure than conventional plug wrap paper.

4. A tobacco smoke filter or filter element according to any preceding claim wherein the further core comprises a core wrapper engaged around the further core.

5. A tobacco smoke filter or filter element according to any preceding claim comprising one or more additional cores longitudinally aligned with the downstream thermoformed and further cores.

6. A tobacco smoke filter or filter element according to any preceding claim wherein the profiled outer surface of the downstream core together with the stiff outer wrapper defines from 1 to 16 longitudinally extending channels extending along the length of the core.

7. A tobacco smoke filter or filter element according to any preceding claim wherein the profiled outer surface of the downstream core together with the stiff outer wrapper defines 4 to 10 longitudinally extending channels extending along the length of the core.

8. A tobacco smoke filter or filter element according to any preceding claim wherein a downstream end of the stiff outer wrapper extends beyond a downstream end of the downstream thermoformed core around which it is engaged to define a cavity at a downstream end of the filter or filter element.

9. A tobacco smoke filter or filter element according to any preceding claim wherein one or more of the downstream thermoformed core, the further core wrapper (if present), the stiff outer wrapper, the or each additional core (if present) and the or each additional core wrapper (if present) is coloured or tinted.

10. A tobacco smoke filter or filter element according to any preceding claim wherein one or more of the further core, the further core wrapper (if present), the stiff outer wrapper, the or each additional core (if present) and the or each additional core wrapper (if present) is a contrasting colour to the colour of the downstream thermoformed core.

11. A tobacco smoke filter or filter element according to any preceding claim wherein the downstream core of thermoformed tobacco smoke filtering material comprises natural or synthetic filamentary tow, for example filamentary tow of cotton or plastics such as polyethylene or polypropylene, cellulose acetate filamentary tow, or extruded material (e.g. starch, synthetic foam, extruded foam).

12. A tobacco smoke filter or filter element according to any preceding claim wherein the downstream core of thermoformed tobacco smoke filtering material comprises a cellulose acetate core formed by the process of: continuously advancing a stream of cellulose acetate through a sizing die having a suitable cross-section to form said core having a profiled outer surface.

13. A tobacco smoke filter or filter element according to any preceding claim wherein the further and additional cores (if present) are each selected from natural or synthetic filamentary tow, for example filamentary tow of cotton or plastics such as polyethylene or polypropylene, or cellulose acetate filamentary tow, natural or synthetic staple fibres, cotton linters, web material such as paper (typically creped) and (e.g. synthetic) non-woven, and extruded material (e.g. starch, synthetic foam, extruded foam).

14. A tobacco smoke filter or filter element according to any preceding claim wherein the further and additional cores (if present) comprise an additive, for example a particulate additive, for example activated carbon.

15. A tobacco smoke filter or filter element according to any preceding claim which includes a flavourant.

16. A tobacco smoke filter or filter element according to any preceding claim which includes a ventilation.

17. A tobacco smoke filter or filter element according to any preceding claim wherein the downstream thermoformed core defines one or more further channels or apertures extending longitudinally through the downstream thermoformed core.

18. A tobacco smoke filter or filter element according to claim 17 wherein there is at least 1.2mm of thermoformed material between the one or more other channels or apertures and the nearest portion of the profiled outer surface.

19. A tobacco smoke filter element comprising a thermoformed core of tobacco smoke filtering material having a profiled outer surface comprising at least one longitudinally extending groove extending along the length of the thermoformed core.

20. The tobacco smoke filter according to item 19, wherein the thermoformed core does not include an additional wrapper conforming to the contoured outer surface profile.

21. The tobacco smoke filter element of item 19 or item 20, wherein the thermoformed core does not include an additional air-impermeable wrapper conforming to the contoured outer surface profile.

22. A tobacco smoke filter element according to any of claims 19 to 21 wherein the profiled outer surface of the core comprises from one to sixteen longitudinally extending grooves extending along the length of the core.

23. A tobacco smoke filter element according to any of claims 19 to 22 further comprising a stiff outer wrapper engaged around the thermoformed core of tobacco smoke filtering material.

24. A tobacco smoke filter or filter element according to any of claims 19 to 23 wherein the thermoformed core defines one or more further channels or apertures extending longitudinally through the thermoformed core.

25. A tobacco smoke filter or filter element according to claim 24 wherein there is at least 1.2mm of thermoformed material between the nearest portion of the profiled outer surface and the further channels or apertures.

26. A tobacco smoke filter or filter element substantially as hereinbefore described with reference to figure 1 or figure 2 of the accompanying drawings.

27. A filter cigarette comprising a filter according to any one of the preceding claims or a filter comprising a filter element according to any one of the preceding claims, the filter being connected to a wrapped tobacco rod.

28. A multi-linked rod comprising a plurality of filters or filter elements according to any of claims 1 to 26 integrally connected end-to-end in mirror image relationship.