Smoking article with ventilated mouth end cavity

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 and less than about (50) percent of the overall filter length. Further, the smoking article comprises a ventilation zone in communication with the cavity at a location along the hollow tube segment.

Claims

1. A smoking article comprising: a tobacco rod; and a filter connected to the tobacco rod, the filter comprising: a first filter segment; and a hollow tube segment downstream of the first filter segment, the hollow tube segment defining a cavity at the downstream end of the filter providing an unrestricted flow channel that extends from the downstream end of the first filter segment to the downstream end of the filter, the cavity being open to an outer environment at the downstream end of the filter, wherein the hollow tube segment does not contain an object which may cause a local restriction of flow of smoke and air, wherein the length of the hollow tube segment is at least about 25 percent, and less than about 50 percent, of the overall filter length and wherein the smoking article comprises a ventilation zone in communication with the cavity at a location along the hollow tube segment, wherein the ventilation zone is located from about 10 mm to about 15 mm upstream from the downstream end of the filter, and wherein the length of the hollow tube segment is at least about 10 mm and is less than about 25 mm.

2. The smoking article according to claim 1, wherein the ventilation zone is located at least about 1 mm downstream from the downstream end of the first filter segment.

3. The smoking article according to claim 1, wherein the ventilation zone comprises at least one circumferential row of perforations provided through the hollow tube segment.

4. The smoking article according to claim 3, wherein the at least one circumferential row of perforations comprises from 8 to 30 perforations.

5. The smoking article according to claim 1, wherein the thickness of the hollow tube segment is from about 90 micrometres to about 140 micrometres.

6. The smoking article according to claim 1, wherein the thickness of the hollow tube segment is from about 100 micrometres to about 130 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 7, wherein the hollow tube segment is formed from a plurality of spirally wound paper layers.

9. The smoking article according to claim 7, wherein adjacent paper layers of the hollow tube segment are adhered together by an intermediate layer of an adhesive.

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 ovality of the hollow tube segment after a 50 percent deformation of the filter is less than 25 percent.

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 tube segment 18, a first filter segment 20, which may or may not contain flavour, and a rod end filter segment 22. The hollow tube segment 18 and the filter segments 20 and 22 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.

(7) The first filter segment 20 and the rod end filter segment 22 are formed of a suitable filtration material, such as cellulose acetate tow. Furthermore, the first filter segment 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 22 contains an adsorbent material, such as a carbon-based adsorbent material.

(8) The hollow tube segment 18 defines a mouth end cavity 24 in the filter 14 and provides an unrestricted flow channel 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 18 internally defines a channel having a substantially constant cross-sectional area for the smoke and air to flow through. Further, the hollow tube segment 18 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 18 and flow of smoke and air through the hollow tube segment 18 is unobstructed.

(9) In the embodiment of FIGS. 1 and 2, the length of the hollow tube segment 18 is about 35 percent of the overall filter length. Further, the hollow tube segment 18 may have a wall thickness from about 100 micrometres to about 130 micrometres.

(10) The hollow tube segment 18 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 hollow tube segment 18. In more detail, the ventilation zone 26 comprises two rows of perforations extending through the wall of the hollow tube segment 18. Two rows of perforations also extend through the band of combining plug wrap 23 and through the band of tipping paper 16. The rows 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 wall of the hollow tube segment 18.

(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.