Smoking article with reduced sidestream smoke

Abstract

A smoking article (10) comprises a tobacco rod (12) and a filter (14) connected to the tobacco rod. The filter (14) comprises a flow restrictor (24). The smoking article further comprises a ventilation zone (18) at a location along the filter downstream of the flow restrictor. The diameter of the tobacco rod (12) is from about 5 mm to about 8.5 mm, the tobacco packing density within the tobacco rod is from about 180 mg/cubic centimetre to about 280 mg/cubic centimetre, and the length of the tobacco rod is from about 15 mm to about 45 mm. Further, the tobacco rod (12) is circumscribed by a wrapper (13) having an air permeability of less than about 20 Coresta units, the wrapper being made of a transparent regenerated cellulose film, or cellophane.

Claims

1. A smoking article comprising a tobacco rod and a filter connected to the tobacco rod, the filter comprising a hollow tube segment defining a cavity at the mouth end of the filter and a flow restrictor disposed in the cavity, the smoking article further comprising a ventilation zone at a location along the filter downstream of the flow restrictor, the ventilation zone being in communication with the cavity; wherein a diameter of the tobacco rod is from 7 mm to 8 mm, a tobacco packing density within the tobacco rod is from 180 mg/cubic centimetre to 280 mg/cubic centimetre, and a length of the tobacco rod is from 15 mm to 25 mm; wherein a wall thickness of the hollow tube segment is less than 140 micrometres; and wherein the tobacco rod is circumscribed by a wrapper having an air permeability of less than 20 Coresta units.

2. The smoking article according to claim 1, wherein the wrapper is substantially air impermeable.

3. The smoking article according to claim 1, wherein the wrapper comprises a base web and one or more layers of add-on material applied to the base web, wherein the add-on material reduces the static burn rate of the wrapper.

4. The smoking article according to claim 1, wherein the hollow tube segment has an outer diameter and an inner diameter, at least one cross sectional dimension of the flow restrictor being larger than the inner diameter of the hollow tube such that the flow restrictor engages with the hollow tube to be retained in the hollow tube.

5. The smoking article according to claim 4, wherein the flow restrictor is substantially spherical, the at least one cross sectional dimension of the flow restrictor being a diameter of the spherical flow restrictor.

6. The smoking article according to claim 1, wherein the flow restrictor comprises a transverse barrier extending across the hollow tube segment, at least one orifice being provided in the transverse barrier for the mainstream smoke to flow through.

7. The smoking article according to claim 6, wherein the flow restrictor comprises a first upstream integral tubular portion; a second downstream integral tubular portion of substantially the same external diameter as the first tubular portion; a third central integral tubular portion located between the first and second tubular portions, the third tubular portion being of reduced external diameter compared to the first and second tubular portions; wherein the transverse barrier is provided therein between a first upstream cavity at least partially defined by an inner periphery of the first tubular portion and a second downstream cavity at least partially defined by an inner periphery of the second tubular portion.

8. The smoking article according to claim 5, wherein the ventilation zone comprises at least one circumferential row of perforations at least 3 mm downstream of a centre of the flow restrictor.

9. The smoking article according to claim 6, wherein the ventilation zone comprises at least one circumferential row of perforations at least 3 mm downstream of the transverse barrier.

10. The smoking article according to claim 1, wherein the flow restrictor is adapted to generate a RTD between approximately 150 mm H.sub.2O (about 1470 Pa) and approximately 500 mm H.sub.2O (about 4900 Pa).

11. The smoking article according to claim 1, wherein the ventilation zone is at least 2 mm upstream from a mouth end of the filter.

12. The smoking article according to claim 1, wherein the ventilation zone is less than 20 mm upstream from a mouth end of the filter.

13. A smoking article comprising a tobacco rod and a filter connected to the tobacco rod, the filter comprising a hollow tube segment defining a cavity at the mouth end of the filter and a flow restrictor disposed in the cavity; the smoking article further comprising a ventilation zone at a location along the filter downstream of the flow restrictor, the ventilation zone being in communication with the cavity; wherein the tobacco rod is circumscribed by a wrapper having an air permeability of less than 20 Coresta units; wherein a wall thickness of the hollow tube segment is less than 140 micrometres; and wherein a diameter of the tobacco rod is from 5 mm to 7 mm, a tobacco packing density within the tobacco rod is from 180 mg/cubic centimetre to 280 mg/cubic centimetre, and a length of the tobacco rod is from 35 mm to 45 mm.

14. The smoking article according to claim 13, wherein the wrapper is substantially air impermeable.

15. The smoking article according to claim 13, wherein the wrapper comprises a base web and one or more layers of add-on material applied to the base web, wherein the add-on material reduces the static burn rate of the wrapper.

16. The smoking article according to claim 13, wherein the hollow tube segment has an outer diameter and an inner diameter, at least one cross sectional dimension of the flow restrictor being larger than the inner diameter of the hollow tube such that the flow restrictor engages with the hollow tube to be retained in the hollow tube.

17. The smoking article according to claim 16, wherein the flow restrictor is substantially spherical, the at least one cross sectional dimension of the flow restrictor being a diameter of the spherical flow restrictor.

18. The smoking article according to claim 13, wherein the flow restrictor comprises a transverse barrier extending across the hollow tube segment, at least one orifice being provided in the transverse barrier for the mainstream smoke to flow through.

19. The smoking article according to claim 18, wherein the flow restrictor comprises a first upstream integral tubular portion; a second downstream integral tubular portion of substantially the same external diameter as the first tubular portion; a third central integral tubular portion located between the first and second tubular portions, the third tubular portion being of reduced external diameter compared to the first and second tubular portions; wherein the transverse barrier is provided therein between a first upstream cavity at least partially defined by an inner periphery of the first tubular portion and a second downstream cavity at least partially defined by an inner periphery of the second tubular portion.

20. The smoking article according to claim 17, wherein the ventilation zone comprises at least one circumferential row of perforations at least 3 mm downstream of a centre of the flow restrictor.

21. The smoking article according to claim 18, wherein the ventilation zone comprises at least one circumferential row of perforations at least 3 mm downstream of the transverse barrier.

22. The smoking article according to claim 13, wherein the flow restrictor is adapted to generate a RTD between approximately 150 mm H.sub.2O (about 1470 Pa) and approximately 500 mm H.sub.2O (about 4900 Pa).

23. The smoking article according to claim 13, wherein the ventilation zone is at least 2 mm upstream from a mouth end of the filter.

24. The smoking article according to claim 13, wherein the ventilation zone is less than 20 mm upstream from a mouth end of the filter.

Description

(1) The invention will 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; and

(3) FIGS. 2A and 2B show a side sectional view of the smoking article of FIG. 1 with the filter and rod unwrapped.

(4) FIGS. 1 and 2 illustrate a smoking article 10 in accordance with the present invention. The smoking article 10 comprises a rod 12 of tobacco cut filler which is attached at one end to an axially aligned filter 14. The tobacco rod 12 is circumscribed by a wrapper 13 (see FIG. 2) made of cellophane and has a length of about 20 mm. The diameter of the tobacco rod 12 is about 7.8 mm. The packing density of the tobacco within the tobacco rod 12 is about 265 mg/cubic centimetre. A band of tipping paper 16 circumscribes the filter 14 and a portion of the wrapped tobacco rod 12 to join together the filter 14 and the rod 12.

(5) The smoking article 10 further comprises a ventilation zone 18 at a location along the filter 14. Although not visible in FIG. 1, a flow restrictor is disposed in the filter 14. The filter 14 has a length of about 27 mm.

(6) In more detail, as illustrated in FIG. 2, the filter 14 comprises a hollow tube segment 20 that defines a cavity 22 at the mouth end of the filter 14. A flow restrictor 24 is disposed within the cavity 22. The ventilation zone 18 is located downstream of the flow restrictor 24.

(7) In the embodiment of FIG. 2A, the hollow tube segment 20 is made of filter material. The flow restrictor 24 is provided as a substantially spherical bead. The diameter of the bead 24 is slightly larger than the inner diameter of the hollow tube segment 20, so the bead 24 causes the filter material adjacent the bead 24 to distort slightly and the bead 24 is retained in the hollow tube segment 20 by friction.

(8) In the embodiment of FIG. 2B. The flow restrictor 24 comprises a transverse barrier with at least one orifice in the barrier.