Smoking article having filter with hollow tube segment

Abstract

A smoking article (10) comprises: a tobacco rod (12); a filter (14) in axial alignment with the tobacco rod, the filter (14) comprising: a hollow tube segment (22) having a wall thickness of no more than 0.9 mm; and a filtration portion upstream of the hollow tube segment (22), the filtration portion comprising one or more filter segments (18) (20). The hollow tube segment (22) defines a cavity (26) at the mouth end of the filter (14) providing an unrestricted flow channel that extends from the downstream end of the filtration portion to the mouth end of the filter (14). The hollow tube segment (22) is formed from a fibrous filtration material and comprises a filter plasticiser, wherein the amount of filter plasticiser is at least 22 percent by weight of the fibrous filtration material.

Claims

1. A smoking article comprising: a tobacco rod; a filter in axial alignment with the tobacco rod, the filter comprising: a hollow tube segment having a wall thickness of no more than 0.9 mm; and a filtration portion upstream of the hollow tube segment, the filtration portion comprising one or more filter segments; wherein 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 filtration portion to the mouth end of the filter; and wherein the hollow tube segment is formed from a fibrous filtration material and comprises a filter plasticiser, wherein the amount of filter plasticiser is at least 22 percent by weight of the fibrous filtration material.

2. The smoking article according to claim 1 wherein the hollow tube segment has a wall thickness of no more than 0.6 mm.

3. The smoking article according to claim 1 wherein the hollow tube segment has a wall thickness of at least 0.3 mm.

4. The smoking article according to claim 1 wherein the density of the fibrous filtration material in the hollow tube segment is at least 0.6 grams per cubic centimetre.

5. The smoking article according to claim 4 wherein the density of the fibrous filtration material in the hollow tube segment is at least 0.8 grams per cubic centimetre.

6. The smoking article according to claim 1 wherein the fibrous filtration material forming the hollow tube segment is cellulose acetate.

7. The smoking article according to claim 1 wherein the fibrous filtration material comprises fibres of between 3.5 denier per filament and 9 denier per filament.

8. The smoking article according to claim 1 wherein the fibrous filtration material comprises fibres of between 25000 total denier and 50000 total denier.

9. The smoking article according to claim 1 wherein the filter plasticiser is selected from triacetin, triethylene glycol diacetate (TEGDA), ethylene vinyl acetate, polyvinyl alcohol, starch or combinations thereof.

10. The smoking article according to claim 1 wherein the amount of filter plasticiser is no greater than 30 percent by weight of the fibrous filtration material.

11. The smoking article according to claim 1 wherein the length of the hollow tube segment is at least about 25 percent of the overall filter length.

12. The smoking article according to claim 1 wherein the wet hardness of the filter at the mouth end cavity is within 10 percent of the dry hardness of the filter at the mouth end cavity.

13. The smoking article according to claim 1 wherein the wet hardness of the filter at the mouth end cavity is at least 90 percent.

14. The smoking article according to claim 1 wherein the filter comprises a ventilation zone comprising at least one circumferential row of perforations provided at a location around the filtration portion.

15. A filter for a smoking article, the filter comprising: a hollow tube segment having a wall thickness of no more than 0.9 mm; and a filtration portion upstream of the hollow tube segment, the filtration portion comprising one or more filter segments; wherein 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 filtration portion to the mouth end of the filter; and wherein the hollow tube segment is formed from a fibrous filtration material and comprises a filter plasticiser, wherein the amount of filter plasticiser is at least 22 percent by weight of the fibrous filtration material.

Description

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

(2) FIG. 1 illustrates the definition of hardness, as discussed above;

(3) FIG. 2 shows a smoking article in accordance with the invention; and

(4) FIG. 3 shows the smoking article of FIG. 2 in an unwrapped condition.

(5) FIGS. 2 and 3 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. 3, the filter 14 comprises a hollow tube segment 24, 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 24 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.

(8) 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.

(9) The hollow tube segment 22 defines a mouth end cavity 26 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 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.

(10) The hollow tube segment 22 is an annular segment formed from cellulose acetate tow with a triacetin plasticiser. The amount of triacetin in the cellulose acetate tow corresponds to between 22 percent and 26 percent by weight of the cellulose acetate tow. The hollow tube segment has a wall thickness of 0.6 mm and a density of approximately 1 gram per cubic centimetre.

(11) The filter 14 has a dry hardness at the mouth end of approximately 96 percent and a wet hardness of approximately 92 percent, when measured according to the hardness test procedure set out above. These hardness measurements demonstrate that the hollow tube segment 22 has a very high resistance to moisture so that the rigidity of the hollow tube segment is substantially retained when the filter is wetted. The resistance to deformation of the mouth end cavity 24 is therefore substantially retained during smoking of the smoking article 10.

(12) The smoking article 10 further comprises a ventilation zone 28 at a location along the first filter segment 20. In more detail, the ventilation zone 28 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 24 and through the band of tipping paper 16. The row of perforations extending through the band of combining plug wrap 24 and through the band of tipping paper 16 are substantially aligned with those extending through the first filter segment 20.