Smoking article comprising a segmented rod of smokable material

Abstract

A smoking article comprises: a rod of smokable material having a mouth-end and a distal-end remote from the mouth-end; an outer wrapper circumscribing the rod; and a mouthpiece abutting and attached to the mouth-end of the rod, the rod includes at least two segments (in abutting end-to-end relation, each of the at least two segments) comprises a charge of smokable material contained within an inner wrapper, the diameter of a downstream segment at the mouth-end of the rod is between 0.2 mm and 0.6 mm smaller than the diameter of an upstream segment at the distal end of the rod. In a preferred embodiment, the abutting ends of the at least two segments, which may comprise different tobacco blends, are oriented at an acute or an obtuse angle relative to the longitudinal axis of the rod.

Description

This application claims priority of European Patent Application No. 05251716.6, filed Mar. 21, 2005, the content of which is hereby being incorporated by reference in its entirety for all purposes.

The present invention relates to smoking articles comprising a segmented rod of smokable material and, in particular, to low tar filter cigarettes comprising a segmented tobacco rod.

Conventional smoking articles tend to exhibit an increase in per puff total particulate matter (TPM) delivery as they are progressively smoked. For example, as a conventional filter cigarette is smoked the amount of “tar” in each puff typically increases. Delivered nicotine levels generally follow that of tar level. Accordingly, nicotine levels also tend to increase as one progresses from puff to puff with conventional cigarettes. Such changes in per puff TPM delivery during smoking can have a negative impact on the organoleptic properties experienced by the consumer.

To deliver a more consistent or uniform smoking experience to consumers, it would be desirable to provide a smoking article that exhibits a flatter or more uniform tar delivery profile than known filter cigarettes.

According to the invention there is provided a smoking article comprising: a rod of smokable material having a mouth-end and a distal-end remote from the mouth-end; an outer wrapper circumscribing the rod; and a mouthpiece abutting and attached to the mouth-end of the rod, the rod including at least two segments in abutting end-to-end relation, each of the at least two segments comprising a charge of smokable material contained in an inner wrapper, characterised in that the diameter of a downstream segment at the mouth-end of the rod is between 0.2 mm and 0.6 mm smaller than the diameter of an upstream segment at the distal end of the rod.

Preferably, the diameter of the downstream segment at the mouth-end of the rod is between about 0.3 mm and about 0.6 mm, more preferably between about 0.3 mm and about 0.5 mm, smaller than the diameter of the upstream segment at the distal end of the rod.

The diameter of the upstream segment at the distal end of the rod is preferably substantially equal to the internal diameter of the circumscribed rod. As used herein, the internal diameter of the circumscribed rod is defined as the distance between diametrically opposed points on the inner surface of the outer wrapper i.e. the internal diameter of the circumscribed rod is equal to the external diameter of the circumscribed rod minus twice the thickness of the outer wrapper.

Without wishing to be bound by theory, it is believed that the difference in diameter between the downstream segment and the upstream segment creates a channel that, in use, allows the aerosol generated during smoking of the upstream segment to flow between the inner wrapper of the downstream segment and the outer wrapper of the rod. As the upstream segment is consumed, the generated aerosol flows to the mouthpiece partly through the downstream segment of the rod and, due to the lower resistance to draw thereof, partly through the channel between the inner wrapper of the downstream segment and the outer wrapper of the rod. The filtration effect of the downstream segment of the rod during consumption of the upstream segment is thus limited and consequently the tar per puff deliveries of the upstream segment are increased compared to a smoking article comprising a rod of smokable material of constant diameter. By increasing the tar per puff deliveries, and hence the sensory characteristics, of the puffs arising from consumption of the upstream segment, smoking articles according to the invention enable a more consistent overall smoking experience to be provided to the consumer compared to conventional filter cigarettes.

Preferably, the smokable material is tobacco. Preferably the downstream segment and the upstream segment comprise different tobacco blends, more preferably the upstream segment comprises a stronger tobacco blend than the downstream segment. Where the rod includes three or more segments, preferably each segment comprises a different tobacco blend. The inclusion of a stronger tobacco blend in the upstream segment may be used to further increase the tar per puff deliveries arising from consumption thereof.

It will be appreciated that through appropriate variation of parameters including, but not limited to, the composition and air permeability of the inner and outer wrappers, the number and dimensions of the at least two segments, the type of smokable material and the structure of the mouthpiece, smoking articles according to the invention may be produced having desired attributes such as, for example, a particular total tar delivery and/or puff count. Smoking articles according to the invention find particular application as filter cigarettes having a total tar delivery of between about 1 mg and about 10 mg, preferably of between about 1 mg and about 3 mg.

The abutting ends of the at least two segments are preferably oriented at an acute or an obtuse angle relative to the longitudinal axis of the rod. Preferably, the abutting ends of the at least two segments are oriented at an angle of between about 10° and about 800, more preferably of between about 30° and about 60°, most preferably of between about 40° and about 50°, relative to the longitudinal axis of the rod. It is particularly preferred if the abutting ends of the at least two segments are oriented at an angle of about 45° relative to the longitudinal axis of the rod. Preferably, the non-abutting ends of the at least two segments are substantially perpendicular to the longitudinal axis of the rod.

Where the at least two segments comprise different tobacco blends, orientation of the abutting ends of the at least two segments at an acute or an obtuse angle relative to the longitudinal axis of the rod advantageously results in a smooth transition between the different tar deliveries of the different tobacco blends during smoking. Furthermore, orientation of the abutting ends of the at least two segments at an acute or an obtuse angle relative to the longitudinal axis of the rod also advantageously reduces the risk of coal drop-off during consumption of smoking articles according to the invention.

Preferably, the rod of smokable material includes two or three segments. Where the rod of smokable material includes three or more segments, the diameter of each segment downstream of the upstream segment at the distal end of the rod is preferably between about 0.2 mm and about 0.6 mm, more preferably between about 0.3 mm and 0.6 mm, most preferably between about 0.3 mm and about 0.5 mm, smaller than the diameter of the upstream segment at the distal end of the rod.

Where the rod of smokable material includes two segments, the downstream segment preferably has a length corresponding to about two thirds of the overall length of the rod. Where the rod of smokable material includes three segments, each of the three segments preferably has a length corresponding to about one third of the overall length of the rod.

Preferably, the at least two segments are co-axially aligned, more preferably the at least two segments and the mouthpiece are co-axially aligned.

Preferably, the outer wrapper is cigarette paper. Preferably, the inner wrapper is a highly porous paper, more preferably a highly porous plug wrap, most preferably a plug wrap having an air permeability of between about 3000 cm³/min·cm² and about 24000 cm³/min·cm². In use, the channel created between the highly porous plug wrap and the outer wrapper of the rod, as a result of the difference in diameter between the downstream segment and the upstream segment, produces a longitudinal and an axial dilution effect as the downstream segment is being consumed. The tar per puff deliveries of the puffs arising from consumption of the downstream segment are thereby advantageously reduced compared to a smoking article comprising a rod of smokable material of constant diameter.

To hold the at least two segments in position relative to one another, smoking articles according to the invention may advantageously further include one or more elongate stabilising elements extending longitudinally between the segments. For example, smoking articles according to the invention may further comprise a thread or strand of thin fibrous material such as, for example, flax or hemp, extending axially through the rod of smokable material from proximate the distal end thereof into the mouthpiece. Alternatively, smoking articles according to the invention may further comprise one or more hollow tubes of reconstituted tobacco material extending axially along the rod of smokable material between the segments. As well as holding the at least two segments in position relative to one another and so increasing the structural stability of the smoking article, the inclusion of a hollow tube of reconstituted tobacco material extending between the upstream segment and the downstream segment also advantageously further increases the dilution effect experienced by the downstream segment during consumption.

Preferably, the mouthpiece is of substantially the same diameter as the rod of smokable material. Where smoking articles according to the invention are cigarettes, the mouthpiece preferably has a diameter of between about 5 mm and about 8.5 mm, more preferably of between about 6 mm and about 8.5 mm. The total length of the rod of smokable material and the mouthpiece when combined may, for example, be up to about 130 mm. Preferably, the mouthpiece has a length of between about 15 mm and about 32 mm.

Preferably, the mouthpiece includes at least one filter element. The mouthpiece may, for example, include one or more suitable known single or composite filter elements. Where the mouthpiece includes one or more filter elements, each filter element may be formed from one or more segments and may comprise any suitable known filter materials such as, for example, cellulose acetate, activated carbon and/or other porous materials or components capable of reducing smoke constituents, together with flavorants and/or other smoke modifying materials if desired. The one or more filter elements may be over wrapped with conventional porous paper plug wrap to form the mouthpiece. Preferably, the mouthpiece is attached to the mouth-end of the rod with tipping paper.

The invention is further described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic longitudinal cross-section through a filter cigarette according to a first embodiment of the invention;

FIG. 2 shows a schematic longitudinal cross-section through a filter cigarette according to a second embodiment of the invention;

FIG. 3 shows a schematic longitudinal cross-section through a filter cigarette according to a third embodiment of the invention;

FIG. 4 shows a graph of tar per puff against puff number for a conventional filter cigarette and a filter cigarette according to the invention; and

FIG. 5 shows a graph of smoke nicotine (SN) per puff against puff number for the cigarettes of FIG. 3.

The filter cigarettes according to the first, second and third embodiments of the invention shown in FIGS. 1, 2 and 3, respectively, have several components in common; these components have been given the same reference numerals throughout.

The filter cigarette 10 shown in FIG. 1 generally comprises an elongate cylindrical tobacco rod 12 attached at one end to an axially aligned cylindrical filter element 14 of substantially the same diameter as the tobacco rod 12.

The tobacco rod 12 comprises two segments axially aligned in an abutting end-to-end relationship along the longitudinal axis thereof: a downstream filter-end segment 16, adjacent the filter 14, and an upstream distal-end segment 18, distant from the filter 14.

The abutting axial ends of the downstream filter-end segment 16 and the upstream distal-end segment 18 are of complementary configuration and are disposed such that the plane along which they abut one another is inclined at an acute angle alpha relative to the longitudinal axis of the tobacco rod 12, wherein alpha is approximately 45 degrees. The outer, non-abutting, axial ends of the downstream filter-end segment 16 and the upstream distal-end segment 18 are substantially perpendicular to the longitudinal axis of the tobacco rod 12.

The downstream filter-end segment 16 and the upstream distal-end segment 18 each comprise a charge of tobacco contained in an inner wrapper 20 of high porosity plug wrap. The individually wrapped downstream filter-end segment 16 and upstream distal-end segment 18 are over wrapped in a cylindrical sleeve 22 of conventional cigarette paper, which forms the outer wrapper of the tobacco rod 12. The tobacco rod 12 and the filter 14 are joined in a conventional manner to form the filter cigarette 10 by tipping paper 24, which circumscribes the entire length of the filter 14 and an adjacent region of the tobacco rod 12, such that the outer, non-abutting, axial end of the downstream filter-end segment 16 of the tobacco rod 12 abuts one end of the filter 14.

The diameter of the downstream filter-end segment 16 in the transverse direction of the filter cigarette 10 is between 0.2 mm and 0.6 mm smaller than the corresponding diameter of the upstream distal-end segment 18. While, as shown approximately in FIG. 1, the length of the downstream filter-end segment 16 in the longitudinal direction of filter cigarette 10 is equal to about two thirds of the total longitudinal length of the tobacco rod 12 and about twice the corresponding length of the upstream distal-end segment 18.

The filter cigarette 26 according to the second embodiment of the invention shown in FIG. 2 has an elongate cylindrical tobacco rod 12 comprising three segments axially aligned in an abutting end-to-end relationship along the longitudinal axis thereof: a downstream filter-end segment 16, adjacent the filter 14, an upstream distal-end segment 18, distant from the filter 14, and a central segment 17, interposed between the downstream filter-end segment 16 and the upstream distal-end segment 18. The downstream filter-end segment 16, the central segment 17 and the upstream distal-end segment 18 each comprise a charge of tobacco contained in a high porosity plug wrap 20 and are once again over wrapped in a cylindrical sleeve 22 of conventional cigarette paper, which forms the outer wrapper of the tobacco rod 12.

The abutting axial ends of the downstream filter-end segment 16 and the central segment 17 and the abutting axial ends of the upstream distal-end segment 18 and the central segment 17 are of complementary configuration and are disposed such that the planes along which they abut one another are inclined at an acute angle alpha relative to the longitudinal axis of the tobacco rod 12, wherein alpha is approximately 45 degrees. The outer, non-abutting, axial ends of the downstream filter-end segment 16 and the upstream distal-end segment 18 distant from the central segment 17 are substantially perpendicular to the longitudinal axis of the tobacco rod 12.

The diameter of the downstream filter-end segment 16 and the diameter of the central segment 17, in the transverse direction of the filter cigarette 10, are between 0.2 mm and 0.6 mm smaller than the corresponding diameter of the upstream distal-end segment 18, the diameter of the downstream filter-end segment 16 being smaller than the diameter of the central segment 17. The lengths of the downstream filter-end segment 16, central segment 17 and upstream distal-end segment 18 in the longitudinal direction of the filter cigarette 10 are approximately the same and equal to about one third of the total longitudinal length of the tobacco rod 12.

The filter cigarettes 10 according to the first and second embodiments of the invention described above may, further comprise one or more elongate stabilising elements, which extend longitudinally between the segments thereof.

For example, as shown in FIG. 2, the filter cigarette 10 according to the second embodiment of the invention may further comprise a central thread or strand 30 (shown by dashed lines) of fibrous material such as flax or hemp, which extends axially through the tobacco rod 12 from the upstream distal-end segment 18 into the filter 14. The thread or strand 30 may extend axially along the entire length of the tobacco rod 12, from the distal-end thereof, into the filter 14, as illustrated in FIG. 2. Alternatively, the thread or strand 30 may extend from, for example, the middle of the upstream distal-end segment axially along the tobacco rod 12 into the filter 14.

As shown in FIG. 2, the filter cigarette 10 according to the second embodiment of the invention may also further comprise a hollow tube 32 of reconstituted tobacco material (shown by dotted and dashed lines), which extends axially through the tobacco rod 12 from the upstream distal-end segment 18 into the downstream filter-end segment 16. It will be appreciated that, as an alternative to a single hollow tube that extends axially along the rod from the upstream segment to the downstream segment, smoking articles according to the invention comprising tobacco rods including three or more segments may include a plurality of hollow tubes of reconstituted tobacco material each of which extends axially along the rod between a neighbouring pair of segments.

To produce the filter cigarettes 10 shown in FIGS. 1 and 2, the downstream filter-end segment 16, upstream distal-end segment 18 and, where present, central segment 17 are produced separately by wrapping charges of tobacco in a high porosity plug wrap 20 using conventional techniques. The individually wrapped segments are then aligned and over wrapped in the cylindrical sleeve 22 of cigarette paper using, for example, known filter assembling machinery, to form the circumscribed tobacco rod 12, which is attached in a conventional manner to the filter element 14 with the tipping paper 24.

The filter cigarette 40 according to the third embodiment of the invention shown in FIG. 3 comprises an elongate cylindrical tobacco rod 12 attached at one end to an axially aligned cylindrical composite filter 14. The tobacco rod 12 comprises two segments axially aligned in an abutting end-to-end relationship along the longitudinal axis thereof: a downstream filter-end segment 16, adjacent the composite filter 14, and an upstream distal-end segment 18, distant from the composite filter 14. As shown in FIG. 3, the abutting axial ends of the downstream filter-end segment 16, which is about 42 mm in length, and the upstream distal-end segment 18, which is about 15 mm in length, are substantially perpendicular to the longitudinal axis of the tobacco rod 12. The outer, non-abutting, axial ends of the downstream filter-end segment 16 and the upstream distal-end segment 18 are also substantially perpendicular to the longitudinal axis of the tobacco rod 12. The diameters of the downstream filter-end segment 16 and the upstream distal-end segment 18 in the transverse direction of the filter cigarette 26 are about 7.3 mm and about 7.78 mm, respectively.

The composite filter 14 comprises three filter segments axially aligned in an abutting end-to-end relationship along the longitudinal axis thereof: an upstream rod-end segment 42, adjacent the tobacco rod 12, a downstream mouth-end segment 46, distant from the tobacco rod 12, and a central segment 44, interposed between the upstream rod-end segment 42 and the downstream mouth-end segment 46. The filter segments 42, 44, 46 may comprise any suitable known filter materials. For example, the upstream rod-end segment 42, which is about 6 mm in length, and the downstream mouth-end segment 46, which is about 15 mm in length, may be cellulose acetate filter segments and the central segment 44, which is about 6 mm in length, may be a paper filter segment.

To produce the filter cigarette 40 shown in FIG. 3, the upstream rod-end segment 42 of the composite filter 14, the downstream filter-end segment 16 of the tobacco rod 12 and the upstream distal-end segment 18 of the tobacco rod 12 are produced separately as previously described and then aligned and over wrapped in the cylindrical sleeve 22 of cigarette paper using known filter assembling machinery to form a rod having a length of about 63 mm. This rod is then joined to the downstream mouth-end segment 46 of the composite filter 14 and the central segment 44 of the composite filter 14 with the tipping paper 24 in a conventional manner using known filter cigarette making machinery.

In use, the filter cigarettes 10, 26, 40 according to the first, second and third embodiments of the invention shown in FIGS. 1 and 2 and 3, respectively, are smoked by the consumer in a conventional manner.

EXAMPLE 1

A filter cigarette according to the invention having the general construction shown in FIG. 1 is prepared by attaching a tobacco rod including a filter-end segment and a distal-end segment to a filter including a mouth-end segment and a tobacco-end segment with tipping paper.

The tobacco rod is formed by over wrapping the filter-end segment and the distal-end segment, each of which comprises a charge of tobacco wrapped in a high porosity plug wrap, in cigarette paper. The distal-end segment of the tobacco rod comprises a stronger tobacco blend (higher % total alkaloid content and lower % expanded tobacco content) than the filter-end segment.

The filter is formed by over wrapping the mouth-end segment and the tobacco-end segment, each of which comprises a plug of cellulose acetate tow of “Y” cross-section wrapped in high porosity plug wrap, in high porosity plug wrap.

The dimensions and resistance to draw (RTD expressed in mm water gauge) of the tobacco rod and filter are given in Table 1 below, together with the dimensions of the filter-end segment and the distal-end segment of the tobacco rod and the mouth-end segment and the tobacco-end segment of the filter.

Plots of average tar per puff and average smoke nicotine per puff versus puff number for fifty of the filter cigarettes according to the invention, smoked under standard machine smoking conditions, are shown in FIGS. 4 and 5, respectively. For comparison, plots of average tar per puff and average smoke nicotine per puff against puff number for fifty conventional low tar filter cigarettes, with the total tar delivery, total smoke nicotine delivery and puff count listed in Table 1, are also shown in FIGS. 4 and 5, respectively.

All air permeability, tar and smoke nicotine values are measured in accordance with the methods specified in ISO 2965, ISO 4387 and ISO 10315, respectively.

As shown in FIGS. 4 and 5, the average tar per puff and average smoke nicotine per puff deliveries of the conventional low tar filter cigarettes show a progressive increase with puff number. In contrast, following initial increases during the first two to three puffs, the filter cigarettes according to the invention exhibit a substantially “flat” average tar per puff and average smoke nicotine per puff delivery profile. The present invention thus advantageously provides filter cigarettes having a low total tar delivery, which exhibit less variation in tar per puff (and consequently smoke nicotine per puff) deliveries than conventional low tar filter cigarettes.

	TABLE 1
		EXAMPLE 1	CONVENTIONAL
	Filter	Tobacco Rod	FILTER CIGARETTE
RTD (mm WG)	163	97
Dilution (%)	72	—
External Diameter (mm)	7.92
					CONVENTIONAL
Segment	Mouth-end	Tobacco-end	Filter-end	Distal-end	FILTER CIGARETTE
RTD (mm WG)	70	92	—	—
Denier per filament	2.6	1.5	—	—
Total denier	42000	46000	—	—
Length (mm)	15	12	38	19
Diameter (mm)	7.78	7.3	7.6
Total alkaloid content (%)	—	—	2.1%	3.2%
Expanded tobacco content	—	—	40%	20%
Plug wrap porosity	12000
(cm3/min · cm2)
Cigarette paper porosity	—	—	46
(cm3/min · cm2)
Total tar (mg)	1.37	1.1-1.4
Total smoke nicotine (mg)	0.186	0.12-0.14
Puff count	7.61	7.0-7.2

Claims

1. A smoking article comprising: a rod of smokable material having a mouth-end and a distal-end remote from the mouth-end; an outer wrapper circumscribing the rod; and a mouthpiece abutting and attached to the mouth-end of the rod, the rod including at least two segments in abutting end-to-end relation, each of the at least two segments comprising a charge of smokable material contained within an inner wrapper, characterised in that the diameter of a downstream segment at the mouth-end of the rod is between 0.2 mm and 0.6 mm smaller than the diameter of an upstream segment at the distal end of the rod.

2. A smoking article according to claim 1 wherein the diameter of the downstream segment is between 0.3 mm and 0.6 mm, smaller than the diameter of the upstream segment.

3. A smoking article according to claim 1 wherein the downstream segment and the upstream segment comprise different tobacco blends.

4. A smoking article according to claim 3 wherein the upstream segment comprises a stronger tobacco blend than the downstream segment.

5. A smoking article according to claim 1 wherein the abutting ends of the at least two segments are oriented at an acute or an obtuse angle relative to the longitudinal axis of the rod.

6. A smoking article according to claim 5 wherein the abutting ends of the at least two segments are oriented at an angle of between 10° and 80°, relative to the longitudinal axis of the rod.

7. A smoking article according to claim 5 wherein the abutting ends of the at least two segments are oriented at an angleof about 45° relative to the longitudinal axis of the rod.

8. A smoking article according to claim 1 wherein the at least two segments are coaxially aligned.

9. A smoking article according to claim 1 wherein the inner wrapper is a porous plug wrap.

10. A smoking article according to claim 1 wherein the mouthpiece comprises at least one filter element.

11. A smoking article according to claim 1 wherein the rod includes two segments and the length of the downstream segment corresponds to about two thirds of the overall length of the rod.

12. A smoking article according claim 1 wherein the rod includes three segments and the length of each segment corresponds to about one third of the overall length of the rod.

13. A smoking article according to claim 1 further comprising at least one elongate stabilising element extending longitudinally along the rod between an adjacent pair of the at least two segments.

14. A smoking article according to claim 1 wherein the diameter of the downstream segment is between 0.3 mm and 0.5 mm, smaller than the diameter of the upstream segment.

15. A smoking article according to claim 5 wherein the abutting ends of the at least two segments are oriented at an angle of between 30° and 60°, relative to the longitudinal axis of the rod.

16. A smoking article according to claim 5 wherein the abutting ends of the at least two segments are oriented at an angle of between 40° and 50°, relative to the longitudinal axis of the rod.