Smoking article with a mouth end cavity and ventilation

Abstract

A smoking article comprises a tobacco rod and a filter connected to the tobacco rod. The filter comprises a first filter segment and a hollow tube segment downstream of the first filter segment. The hollow tube segment defines a cavity at the mouth end of the filter providing an unrestricted flow channel that extends from the downstream end of the first filter segment to the mouth end of the filter. The length of the hollow tube segment is at least about 25 percent of the overall filter length. Further, the smoking article comprises a ventilation zone comprising at least one circumferential row of perforations provided at a location around the first filter segment.

Claims

1. A smoking article comprising: a tobacco rod; and a filter connected to the tobacco rod, the filter comprising: a hollow mouth end portion; and a filtration portion upstream of the hollow mouth end portion, the filtration portion comprising one or more filter segments; wherein the hollow mouth end portion is formed by a hollow tube segment that is disposed at a mouth end of the filter, the hollow tube segment being circumscribed by a wrapper in order to maintain axial alignment of the hollow tube segment with the filtration portion and the hollow mouth end portion defining cavity providing an unrestricted flow channel that extends from the downstream end of the filtration portion to the mouth end of the filter, wherein the length of the hollow mouth end portion is within 5 mm of the length of the filtration portion and wherein the smoking article comprises a ventilation zone comprising at least one circumferential row of perforations provided at a location at least about 5 mm upstream from the downstream end of the filtration portion, wherein the one or more filter segments of the filtration portion comprise a first filter segment, and wherein the length of the first filter segment is at least 8 mm.

2. The smoking article according to claim 1, wherein the length of the hollow tube segment is less than about 50 percent of the overall filter length.

3. The smoking article according to claim 1, wherein the length of the hollow tube segment is less than about 30 mm.

4. The smoking article according to claim 1, wherein the length of the hollow tube segment is at least about 8 mm.

5. The smoking article according to claim 1, wherein the wall thickness of the hollow tube segment is at least about 100 micrometres.

6. The smoking article according to claim 1, wherein the wall thickness of the hollow tube segment is at least about 200 micrometres.

7. The smoking article according to claim 1, wherein the hollow tube segment is formed from a plurality of overlapping paper layers.

8. The smoking article according to claim 1, wherein the hollow tube segment is formed from an annular shaped segment of filtration material.

9. The smoking article according to claim 8, wherein the annular shaped segment of filtration material comprises fibres of between approximately 1.5 denier per filament (dpf) and approximately 8 dpf.

10. The smoking article according to claim 1, wherein the difference between the ovality of the hollow tube segment after 50 percent deformation of the filter and the ovality of the hollow tube segment prior to deformation of the filter is less than 25 percent.

11. The smoking article according to claim 1, wherein the length of the hollow tube segment is within 2 mm of the length of the first filter segment.

12. The smoking article according to claim 1, wherein the length of the hollow tube segment is less than the length of the first filter segment.

13. The smoking article according to claim 1, wherein the at least one circumferential row of perforations is provided at least 18 mm from the mouth end of the filter.

14. The smoking article according to claim 1, wherein the at least one circumferential row of perforations is disposed a distance from the mouth end that is at least 50 percent of the overall filter length.

15. The smoking article according to claim 1, wherein the filter is attached to the tobacco rod by a band of tipping paper, the tipping paper comprising paper having a basis weight of more than about 20 grams per square metre.

16. The smoking article according to claim 15, wherein the tipping paper comprises paper having a basis weight of less than about 70 grams per square metre.

Description

(1) The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows a smoking article in accordance with the present invention;

(3) FIG. 2 shows the mouth end of the smoking article of FIG. 1 with the filter unwrapped; and

(4) FIG. 3 shows an exemplary method of forming a tubular member for forming hollow tube segments in accordance with the present invention.

(5) FIGS. 1 and 2 illustrate a smoking article 10 in accordance with the present invention. The smoking article 10 comprises a wrapped rod 12 of tobacco cut filler which is attached at one end to an axially aligned filter 14. A band of tipping paper 16 circumscribes the filter 14 and a portion of the wrapped rod 12 of tobacco to join together the two portions of the smoking article 10.

(6) As shown in FIG. 2, the filter 14 comprises a hollow mouth end portion 21 formed by a hollow tube segment 22 and a filtration portion 27 comprising a first filter segment 20, which may or may not contain flavour, and a rod end filter segment 18. The upstream end of the hollow tube segment 22 abuts the downstream end of the first filter segment 20. The upstream end of the first filter segment 20 abuts the downstream end of the rod end filter segment 18. The upstream end of the rod end filter segment 18 abuts the tobacco rod 12. The hollow tube segment is 10 mm long. The first filter segment is 12 mm long. The rod end filter segment is 12 mm long. The overall filter length is 34 mm.

(7) The hollow tube segment 22 and the filter segments 20 and 18 are circumscribed by a band of combining plug wrap 23 which connects the three segments to form the filter 14. One or more of the segments 18, 20, 22 may additionally be wrapped in an individual plug wrap. The first filter segment 20 and the rod end filter segment 18 are formed of a suitable filtration material, such as cellulose acetate tow. Furthermore, the first filter segment 20 may comprise a suitable flavourant, which may be provided in the form of one or more breakable capsules contained within the first filter segment 20. In this case, the one or more breakable capsules are ruptured by the consumer when desired by squeezing the first filter segment 20 between the consumer's fingers. The rod end filter segment 18 contains an adsorbent material, such as a carbon-based adsorbent material.

(8) The hollow tube segment 22 defines a mouth end cavity 24 in the filter 14 and provides an unrestricted flow channel 25 which extends between the downstream end of the first filter segment 20 and the mouth end of the filter 14. In more detail, the hollow tube segment 22 internally defines a channel having a substantially constant cross-sectional area for the smoke and air to flow through. Further, the hollow tube segment 22 does not contain any object adapted to cause a local restriction of the flow of the smoke and air. Thus, the cross-sectional area available for the smoke and air to flow through is substantially constant along the whole length of the hollow tube segment 22 and flow of smoke and air through the hollow tube segment 22 is unobstructed.

(9) In the embodiment of FIGS. 1 and 2, the length of the hollow tube segment 22 is about 30 percent of the overall filter length. Further, the hollow tube segment 22 may have a wall thickness from about 100 micrometres to about 300 micrometres.

(10) The hollow tube segment 22 may be formed of a plurality of spirally wound paper layers which can further improve the resistance to deformation of the mouth end cavity 24, for example during smoking or during rupture of the one or more breakable capsules when present in the first filter segment 20. The ovality of the hollow tube segment after a 50 percent deformation of the filter 14 may be less than 25 percent.

(11) The smoking article 10 further comprises a ventilation zone 26 at a location along the first filter segment 20. In more detail, the ventilation zone 26 comprises a row of perforations extending through the first filter segment 20. The row of perforations is located 10 mm upstream of the downstream end of the first filter segment. A row of perforations also extend through the band of combining plug wrap 23 and through the band of tipping paper 16. The row of perforations extending through the band of combining plug wrap 23 and through the band of tipping paper 16 are substantially aligned with those extending through the first filter segment 20.

(12) FIG. 3 shows an exemplary method of forming a hollow tube member 30 which can be cut to form a plurality of hollow tube segments for use in forming smoking articles in accordance with the present invention. A plurality of continuous paper plies 32 are spirally wound around a cylindrical mandrel 34 in a staggered, overlapping arrangement. A suitable adhesive may be applied to one or more of the plies 32 using an adhesive bath 36 prior to winding each ply around the mandrel 34. The plies 32 are driven by a rubber belt 38 so that the formed tubular member 30 rotates around the mandrel 34 until it is cut into desired lengths further downstream.