Tobacco smoke filter

Abstract

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 having a profiled outer surface which defines with the stiff outer wrapper at least one longitudinally extending channel which extends the length of the downstream core.

Claims

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 separate from the downstream thermoformed core and longitudinally aligned therewith; the downstream thermoformed core having a profiled air permeable outer surface which defines with the stiff outer wrapper at least one longitudinally extending channel which extends a length of the downstream thermoformed core, wherein no further wrap is positioned between the profiled outer surface of the downstream thermoformed core of tobacco smoke filtering material and the stiff outer wrapper, wherein the stiff outer wrapper has a basis weight from about 80 to 120 gsm, wherein a terminal edge of the downstream end of the stiff outer wrapper surrounds the downstream end of the downstream thermoformed core around which the stiff outer wrapper is engaged.

2. The tobacco smoke filter or filter element according to claim 1, wherein the stiff outer wrapper comprises a stiff paper.

3. The tobacco smoke filter or filter element according to claim 1, further including a core wrapper engaged around the further core.

4. The tobacco smoke filter or filter element according to claim 1, further including at least one additional core longitudinally aligned with the downstream thermoformed core and the further core.

5. The tobacco smoke filter or filter element according to claim 1, wherein the profiled outer surface of the downstream thermoformed core defines with the stiff outer wrapper 1 to 16 longitudinally extending channels which extend along the length of the downstream thermoformed core.

6. The tobacco smoke filter or filter element according to claim 1, wherein the profiled outer surface of the downstream thermoformed core defines with the stiff outer wrapper 4 to 10 longitudinally extending channels which extend along the length of the downstream thermoformed core.

7. The tobacco smoke filter or filter element according to claim 1, wherein at least one of the downstream thermoformed core, the further core, and the stiff outer wrapper is coloured or tinted.

8. The tobacco smoke filter or filter element according to claim 1, wherein at least one of the further core and the stiff outer wrapper is a contrasting colour to a colour of the downstream thermoformed core.

9. The tobacco smoke filter or filter element according to claim 1, wherein the downstream thermoformed core of tobacco smoke filtering material comprises natural or synthetic filamentary tow, cellulose acetate filamentary tow, or extruded material.

10. The tobacco smoke filter or filter element according to claim 1, wherein the downstream thermoformed core of tobacco smoke filtering material comprises a cellulose acetate core formed by continuously advancing a flow of cellulose acetate through a shaped die of suitable cross section to form the downstream thermoformed core with the profiled outer surface.

11. The tobacco smoke filter or filter element according to claim 1, wherein the further core is individually selected from a natural or synthetic filamentary tow; a natural or synthetic staple fibre; cotton wool; web material; and extruded material.

12. The tobacco smoke filter or filter element according to claim 1, wherein the further core includes additive.

13. The tobacco smoke filter or filter element according to claim 1 which includes a flavouring agent.

14. The tobacco smoke filter or filter element according to claim 1 which includes ventilation.

15. The tobacco smoke filter or filter element according to claim 1, wherein the downstream thermoformed core defines at least one further channel or bore which extends longitudinally through the downstream thermoformed core.

16. The tobacco smoke filter or filter element according to claim 15, wherein there is at least 1.2 mm of thermoformed material between the at least one further channel or bore and a closest part of the profiled outer surface.

17. A filter cigarette comprising a filter or a filter including a filter element according to claim 1, joined to a wrapped tobacco rod.

18. A multiple rod comprising a plurality of filters or filter elements according to claim 1 integrally joined end-to-end in a mirror image relationship.

19. The tobacco smoke filter or filter element according to claim 1, wherein the terminal edge is positioned in line with the downstream end of the downstream thermoformed core.

Description

(1) According to the present invention in a further 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 which includes at least one longitudinally extending groove which extends (e.g. continuously) the (full) length of the thermoformed core. The profiled (e.g. corrugated) outer surface of the (thermoformed) core may include from one to sixteen longitudinally extending grooves (preferably 4 to 10 grooves, e.g. 5 to 10 grooves) which extend (e.g. continuously) along the thermoformed core (along the full length of the core).

(2) 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 therefore define with the (inner surface of the) stiff outer wrapper at least one (e.g. covered) longitudinally extending channel which extends (e.g. continuously) the (full) length of the core (formed by the stiff outer wrapper covering the groove(s) in the outer surface of the core).

(3) Preferably the stiff outer wrapper comprises a stiff paper, for example a stiff plugwrap paper. The stiff outer wrapper may be a paper (e.g. plugwrap paper) of basis weight from about 80 to 120 gsm. The stiff outer wrapper may be a paper (e.g. plugwrap paper) of lighter weight, for example of basis weight 30 to 80 gsm, to which additives have been applied to make it stiff, as well known in the art. Stiff papers, for example stiff plugwrap papers, are well known in the art.

(4) Preferably the thermoformed core does not include a further wrapper (e.g. air impermeable wrapper) following the profiles of (for example adhering to) the profiled outer surface. In other words it is preferred that there is no further 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 coherent, bonded, (smoke-permeable) material (e.g. cellulose acetate). Herein the term coherent means self supporting; the coherent bonded thermoformed core material holds its shape and profiled surface without requirement for a shaped wrapper (to hold it in shape). Suitable materials for the thermoformed core are as described above for the downstream thermoformed core.

(5) 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 overall cross-sectional area of the (downstream) thermoformed core of the filter. Careful control over the number and/or depth of the channels (e.g. determined by the thermoforming process which the downstream core is made) may give improved filtering performance and/or sensory characteristics. This may be achieved by increasing the depth of the corrugations, preferably with increase in surface area of the corrugations, and optionally along with increase in the corrugation pitch—that is widening of the corrugations with reduction in their number. For example, a filter according to the invention may have five channels which are about 0.75 mm deep and at a pitch of about 2.0 mm.

(6) According to the invention in a further aspect there is provided a multiple rod comprising a plurality (e.g. 2, 4, 6 etc.) of filters (or filter elements) as described above and/or herein integrally joined end-to-end in a mirror image relationship.

(7) The present invention will now be illustrated with reference to the following Examples and the attached drawings in which FIG. 1 schematically illustrates a filter according to a first embodiment of the invention; and FIG. 2 shows the downstream end view of a filter according to a further embodiment of the invention.

(8) FIG. 1 shows a tobacco smoke filter 1 of length 30 mm and circumference around 25 mm which includes a stiff outer wrapper 2 (shown by the dotted line) of stiff plugwrap paper of basis weight 100 gsm. The stiff outer wrapper is engaged around a downstream longitudinally extending thermoformed core 3 of tobacco smoke filtering material of length 15 mm; and a longitudinally extending substantially cylindrical further core 4 of tobacco smoke filtering material, also of length 15 mm. The further core 4 is longitudinally aligned with the thermoformed core 3 and the downstream end of the further core 4 is abutted to the upstream end of the downstream thermoformed core of tobacco smoke filtering material. The stiff outer wrapper includes ventilation (not shown).

(9) The downstream thermoformed core 3 is formed from cellulose acetate tow to which a glyceryl triacetate plasticiser has been applied. The core 3 is formed in a multiple length of cores by continuously drawing and/or gathering a flow of tobacco smoke of cellulose acetate tow bearing plasticiser through a shaped die to form an advancing multiple length of cores with profiled outer surface, and heat treating the advancing multiple length of cores as and/or or shortly after it is formed (with a subsequent cooling step) by methods similar to those disclosed in WO2011/148130. The heat treatment and cooling activates the plasticiser to form the cellulose acetate material into a multiple length of coherent, bonded, smoke-permeable downstream thermoformed cores having profiled (e.g. grooved e.g. corrugated) outer surface. The multiple length of cores is then cut down to single cores 3 during filter or cigarette formation by methods well known in the art

(10) The downstream thermoformed core 3 has a profiled outer surface which includes four longitudinally extending grooves 5. Each groove 5 defines with the inner surface of the stiff outer wrapper a longitudinally extending channel (which is covered by the wrapper 2), which extends continuously the full length of downstream core 3.

(11) The further core 4 is a non-wrapped substantially cylindrical core of cellulose acetate, for example such as a non wrapped acetate (NWA) filter segment, such as is well known in the art.

(12) It will be appreciated that filters such as those illustrated in FIG. 1 may be made by methods well known in the art, by for example by longitudinally advancing a continuous flow of component multiple (e.g. dual) filter rods (arranged appropriately, e.g. with dual component rods which will form the downstream cores 3 located between dual component rods which will form the further cores 4) to a wrapping garniture where the continuously advancing stiff outer wrapper is wrapped around the longitudinally advancing flow of component multiple filter rods and fixed using a lapped and stuck seam (as is well known). The wrapped longitudinally advancing flow of component multiple filter rods is then cut appropriately for further use, by methods well known in the art.

(13) The filter 1 is joined to a wrapped tobacco rod 6 with the upstream core 4 towards the tobacco. The filter 1 is joined to the wrapped tobacco rod 6 by ring tipping [which engages around just the adjacent ends of the (wrapped) filter and rod to leave much of the stiff wrapper 2 exposed], by methods which are well known in the art.

(14) The applicants have found that the combination of the profiled thermoformed downstream core and the stiff outer wrapper gives better end definition than previous comparable products, because the covered channels are not crushed or distorted during the subsequent processes of filter and filter cigarette manufacture and use; this is useful for anti-counterfeit purposes. The thermoformed core is coherent and self supporting and therefore does not require a further wrapper (e.g. air impermeable wrapper) which follows the profiles of the profiled outer surface; this may result in improved smoking qualities (e.g. by reducing or negating the “air and smoke” effect) because ventilating air may enter the downstream core through the ventilation and/or longitudinally extending channels.

(15) In a further example (not shown), a tobacco smoke filter similar to that illustrated in FIG. 1 includes a further NWA core which is coloured or tinted red (e.g. using appropriate dyes or pigments with regulatory approval for use in food contact applications), and the downstream thermoformed core comprises white cellulose acetate (as in FIG. 1). It will be appreciated that in this example the red colour of the further core will contrast with, and therefore be visible at the upstream end of the longitudinally extending channel(s) in, the downstream thermoformed core, when the downstream end of the downstream core is viewed “end on” along the longitudinal axis of the filter/element. This contrast provides a product filter, element or rod with an enhanced distinctive appearance that is useful for anti-counterfeit purposes.

(16) FIG. 2 shows the downstream end view of a further embodiment of the invention. In this embodiment, tobacco smoke filter 10 of length 30 mm and circumference around 25 mm includes a stiff outer wrapper 12 (shown by the bold line) of stiff plugwrap paper of basis weight 100 gsm. The stiff outer wrapper is engaged around a downstream longitudinally extending thermoformed core 13 of tobacco smoke filtering material of length 15 mm; and a longitudinally extending substantially cylindrical further core of tobacco smoke filtering material, also of length 15 mm (not shown). The further core is longitudinally aligned with the thermoformed core 13 and the downstream end of the further core is abutted to the upstream end of the downstream thermoformed core 13 of tobacco smoke filtering material. The stiff outer wrapper includes ventilation (not shown).

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

(18) The downstream thermoformed core 13 defines a further channel or bore 17 of circular cross section which extends longitudinally through the downstream thermoformed core. The bore 17 extends through the downstream thermoformed core from the downstream end to the upstream end. As seen in FIG. 2, bore 17 extends through the centre of the downstream thermoformed core (that is, along the central axis of the core).

(19) As shown in FIG. 2 (although not to scale), there is at least 1.2 mm of thermoformed material between the periphery of the bore 13 and the closest part of the profiled outer surface of core 13.

(20) The downstream thermoformed core 13 is formed from cellulose acetate tow to which a glyceryl triacetate plasticiser has been applied, in a similar manner to that used to form thermoformed core 3 of the example of FIG. 1.

(21) The further core (not shown) is a non-wrapped substantially cylindrical core of cellulose acetate, for example such as a non wrapped acetate (NWA) filter segment, such as is well known in the art.

(22) The filter 10 may be joined to a wrapped tobacco rod with the upstream core towards the tobacco. The filter is joined to the wrapped tobacco rod by ring tipping [which engages around just the adjacent ends of the (wrapped) filter and rod to leave much of the stiff wrapper 2 exposed], by methods which are well known in the art.

(23) The example of FIG. 2 has bore 17 of circular cross section. It will be appreciated that in other examples of the invention (not shown), the bore may have a cross section of any shape, e.g. a circular, oval, star, heart, trilobal, pentagonal, cog or logo shaped cross section. In other examples (not shown), the downstream thermoformed core may define more than one (e.g. narrow) bore, rather than a single bore.