IE902555A1 - Cigarettes - Google Patents

Abstract

A cigarette or cigar comprising a rod of tobacco which decreases in strength from the kindled end to the other end and which is provided with a filter, the filtration efficiency of which increases as the cigarette is consumed.

Description

This invention relates to cigarettes which are of improved uniformity as to the strength of the smoke, flavour and aroma throughout the smoking.

It is well known that a conventional cigar or cigarette filled with a tobacco of uniform quality grows stronger to the taste and increases in nicotine delivery as it is consumed as a result of the partial condensation, on the unburnt tobacco, of nicotine and other smoke constituents generated in early puffs and the subsequent release of these materials along with the combustion products of the tobacco in later puffs .

It has been proposed that the typical puff-by-puff strength and flavour profile may be modified and made more uniform by the use of tobaccos of different quality within separate zones of the tobacco rod.

O.A. Elias (G.B. 8,577) proposed the use of discrete segments with a different tobacco in each segment.

N.M. Hopkins (G.B. 250,063) disclosed the use of a blend of strong tobacco which occupies a space of gradually decreasing cross-section from the kindled end towards the end through which the smoke is drawn with a tobacco of mild composition filling the remainder of the space; for example, the strong tobacco may be in the form of a cone.

G.B. 1,340,100 of B.A.T. suggests the use of natural tobacco in a first smoked portion and reconstituted tobacco or tobacco substitute in a second portion, the two portions being in the form of two wedges or, alternatively, the first portion being a core of conical or frusto-conical shape. -2G.B. 1,343,402 of Olin Corporation makes use of a shredded carbon filled paper incorporated to replace tobacco in increasing amounts towards the butt end of the cigarette to achieve a more uniform yield of smoke as the cigarette is consumed .

U.S. 4,759,380 of R.J. Reynolds Tobacco Company described a cigarette in which the tobacco rod is composed of two segments, each containing a different tobacco, with a filter attached to the second segment; the second segment may contain reconstituted tobacco, expanded tobacco, processed tobacco stems or a blend thereof.

This concept of tobacco rods which vary in tobacco composition along the length may be used to achieve a more uniform puff-by-puff delivery of smoke but very often the final one or two puffs are still found to be somewhat stronger than the previous puffs as a result of the repeated previous exposure to smoke of the tobacco being consumed in the final stages.

In an alternative approach to achieve a more uniform puff-by-puff profile, cigarettes with conventional tobacco rods filled with a tobacco of uniform quality have been provided with special filters which increase in filtration efficiency during smoking.

Examples of such filters are described in G.B. 2,102,271 A, G.B. 2,103,065 A, G.B. 2,105,566 A and G.B. 2,119,225 A of Filtrona (U.K.). These employ two flow paths, a low pressure drop path of low filtration efficiency and a high pressure drop flow path of high filtration efficiency. During the early puffs, the smoke tends to flow through the low pressure drop path, but a blocking mechanism acting through the deposition of tar causes the flow of -3smoke to switch to the high pressure drop path in subsequent puffs .

Other examples are described in U.S. 4,460,000 and U.S. 4,469,112 of Browne et al., and European Patent Application No. 88308323.0 (publication No. 0 310 257) and European Patent Applications Nos. 89310421.6 (Publication No. 0 364 253) and 89310430.7 (Publication No International Tobacco (UK) Limited, an increase in filtration efficiency, for example, by the deposition of tar on fibrous filtration media when the flow of smoke is confined to a narrow stream by passage through orifices in impermeable or low permeability discs or tubes contained within the filter. 364 256) of Rothmans These filters achieve G.B. Patent Application No. CA/90/00070 of Rothmans, Benson and Hedges, Inc. and Rothmans International Services Limited makes use of a fabric of microfine fibres to achieve a variable filter efficiency. The fabric, vzhich has a high filtration efficiency but a low pressure drop, forms the wrap of a core of low pressure drop, low filtration efficiency tow which is enclosed by an annulus of higher pressure drop, higher filtration efficiency tow. The core is crimp-sealed at the end adjacent to the tobacco so that smoke is able to flow either along the outer annulus or through the cylindrical fabric wrap into the core. The deposition of tar on the microfine fibres produces progressive increase in filtration efficiency during smoking. An additional feature of this filter design is that high filtration efficiencies can be achieved, even in the early puffs, at a relatively low filter pressure drop.

All of these special features increase in pressure drop during smoking and, if tip ventilated downstream of the region of the increase in pressure drop, there arises a -4puff-by-puff increase in the level of tip ventilation which assists in creating a more uniform delivery of smoke as the cigarette is consumed.

These special filters are particularly effective in minimising the increase in the smoke yields of the final two puffs of the cigarette.

According to the present invention a cigarette or cigar comprises a rod of tobacco which decreases in strength from the kindled end to the other end and which is provided with a filter, the filtration efficiency of which increases as the cigarette is consumed.

Preferably the tobacco rod comprises two or more different types or blends of tobacco separated into demarcated zones, the tobacco at the kindled end of the cigarette being higher in strength and/or quality and/or flavour and/or nicotine content than at the other end through which the smoke is drawn.

The demarcated zones may be in the form of segments or the zone of stronger tobacco can be wedge shaped, conical or frusto conical.

Where there are wedges, cones or frusto cones of stronger tobacco they may extend throughout substantially the whole length of the tobacco rod.

Where the wedge conical or frusto-conical shape is used over part of the length of the rod the kindled end may be wholly of stronger tobacco.

The material forming the blend of strong tobaccos may include cured and aged flue-cured, Burley, Maryland or -5Oriental tobaccos, or rare speciality tobaccos such as Latikia or fire-cured tobaccos.

The material forming the blend of strong tobaccos may also include expanded tobacco or minor amounts of reconstituted tobacco sheet, processed stems or tobacco substitutes .

The milder blend of tobaccos can include flue-cured, Burley, Maryland or Oriental tobaccos or rare speciality tobaccos of the milder varieties and these milder tobaccos may also include expanded tobaccos, reconstituted tobaccos, processed stems or tobacco substitutes.

Preferably the expanded tobaccos, reconstituted tobaccos, processed stems or tobacco substitute can form of majority part of the milder blend.

The filter may be of the kind set forth in European Patent Application 88308323.0 (Publication No. 0 310 257), the disclosure of which is incorporated herein. This filter comprises a filter element of fibrous material, the fibres of which extend longitudinally between a first end which is for attachment to the tobacco rod and a second end, and which surrounds a longitudinally extending tube member, one end of which is closed and is located at the first end of the filter element and the open end of which extends to the second end of the element, the wall of the tube being provided with one or more radially extending apertures adjacent to its closed end to promote radial flow through the fibres of the filter element adjacent the aperture or apertures and being dimensioned so that they remain open to allow flow communication through the wall of the tube throughout the period that the cigarette is smoked. -6This type of filter is equally effective if assembled to the tobacco rod in the reverse configuration with the open end of the tube in abutment with the tobacco.

The interior of the tube may be empty or filled with a column of filter material and in a preferred construction the tube is formed by an impervious film.

In an alternative construction the filter may be of the kind set forth in European Patent Application No. 89310430.7 (Publication No. 0 364 256) the disclosures of which are incorporated herein and in which the filter comprises a filter element having a flow path therethrough which includes a barrier in the form of a substantially planar disc made from a layer of micro-fine fibres with a diameter of between 0.5 and 10 microns, and provided with one or more flow openings in the range of 0.1 mm to 3.0 mm in diameter 2 2 with a combined total area of between 0.1 mm and 10 mm .

With this arrangement the disc can be located between layers of porous material to form a laminate barrier.

In another alternative construction the filter may comprise a filter element of the kind set forth in European Patent Application No. 89310421.6 (Publication No. 0 364 253), the disclosure of which is incorporated herein and in which the filter comprises a filter element which includes an axially extending barrier tube of micro-fine fibres with a diameter of between 0.5 and 10 microns and located so that at least part of the gas flow passes through the wall of the barrier.

The barrier tube can be provided with one or more flow openings in the range of 0.1 mm to 3.0 mm in diameter with 2 2 a combined total area of between 0.1 mm and 10 mm . -7Preferably the barrier tube is shaped to provide inner and outer coaxial passages through the filter element, one of which is closed at one end and the other of which is closed at the other end so that the flow path passes through the wall of the barrier tube.

With this arrangement the interior of the barrier tube can be empty or it can be filled with a column of filter material.

The filter may also be of the kind set forth in PCT Patent Application CA/90/00070, the disclosure of which is again incorporated in the present Application and in which the filter comprises an annulus of conventional filter material surrounding a cylinder of micro-fine fibres, a smoke flow directing element insuring that all the smoke drawn from the cigarette enters the annulus of conventional filter material and a low resistance filtered smoke path is provided at the interior of the cylinder of the micro-fine fibres .

The invention can be performed in various ways and some embodiments will now be described byway of example and with reference to the accompanying drawings in which : Figure 1 is a cross-sectional side elevation of a cigarette incorporating the invention in which the filter is of the kind described in European Patent Application 88308323.0 (Publication No. 0 310 257); Figure 2 is a cross-section of an alternative construction with the same type of filter; Figure 3 is another construction with the same type of filter; -8Figure 4 shows another construction using the same type of filter with an alternative tobacco arrangement; Figure 5 shows another alternative tobacco arrangement; Figure 6 shows the filter construction in more detail; Figure 7 shows a cigarette with a tobacco arrangement similar to that shown in Figure 5 but with an alternative filter construction in which the tube is filled with a plug of filter tow; Figure 8 shows the filter construction in more detail; Figure 9 shows a cigarette with a tobacco arrangement similar to that shown in Figures 5 and 7 but with another alternative filter construction of the kind set forth in European Patent Application No. 89310430.7 (Publication No. 0 364 256); Figure 10 shows a filter construction in more detail; Figure 11 shows another cigarette construction according to the invention with another alternative filter construction of the kind set forth in European Patent Application No. 89310421.6 (Publication No. 0 364 253) ; and , Figure 12 shows a filter construction in more detail.

A cigarette according to the invention can utilise a tobacco rod of circular or elliptical cross-section wrapped with a suitable cigarette paper and filled with at least two different types of tobaccos or at least two different blends of tobacco separated into demarcation zones within the rod 9so that the tobacco in the region of the kindled end of the cigarette is higher in strength and/or quality and/or flavour and/or nicotine content than the tobacco in the region through which the smoke is drawn.

In the arrangement shown in Figure 1 the demarcated zones of tobacco are in the form of segments , the kindled end of the cigarette being indicated by reference numeral 1 and containing a stronger tobacco than the other end of the tobacco rod 2 through which the smoke is drawn. In none of the drawings is the cigarette paper shown.

The filter indicated by reference numeral 3 is of the kind described in European Patent Application 88308323.0 (Publication No. 0 310 257). It will be appreciated that any of the filters described in this Patent Specification can be used because they provide the necessary progressive filtering effect. In the filter shown the filter rod comprises a plug wrap 6, fibrous material 4 and a tube 5 placed longitudinally along the length of the filter. One end of the tube 5 is closed by being crimped as indicated by reference numeral 8 and the other open end of the tube is indicated by reference numeral 9. A pair of opposed apertures 7 are provided in the wall of the tube adjacent the closed end 8. The construction of this type of filter is more clearly shown in Figure 6.

The various dimensions of the tube are as shown in Figure 2 of the European Patent Application referred to and any of the other variations, as mentioned above, can be employed .

When a cigarette fitted with this filter is smoked, the smoke enters the filter rod and travels inside the fibrous filter material until it reaches the location of the -10apertures in the tube. The smoke now splits into two streams, one stream continues to flow inside the fibrous filter material and the other stream flows into the tube through the apertures. As the smoke stream which is diverted into the tube has only been flowing through a short length of the fibrous material the smoke has therefore not been filtered as extensively as the other smoke stream. The tar concentration of the smoke stream flowing out from the tube in the first puff is therefore higher than that flowing out from the main filter body. As the stream of smoke is being diverted into the tube through the aperture, the flow direction of the smoke is changed from being parallel to the fibres to being at an angle. The radial component of the flow has therefore greatly increased. In such flow conditions, the fibres in the flow path of this smoke are therefore transverse to the direction of flow. Furthermore, both the velocity and momentum of the smoke particles are greatly increased as they converge to flow through the narrow apertures. The combined effects of the increased radial component of the flow and the increased particle momentum have consequently greatly increased the filtration efficiency of the fibres in the vicinity of the apertures. The smoke particles will deposit and accumulate partially on the aperture and partially on the fibrous material around the aperture. It has been found that the size of the aperture and its location on the tube wall can be chosen so that the aperture or apertures will not be completely blocked by the accumulated smoke particles. Furthermore, the size of the apertures and their location can be so chosen that the accumulation of the smoke particles on the fibres around the aperture will lead to an increase in the filtration efficiency of these fibres to an extent related to the quantity of smoke which is passed through the aperture. The smoke stream inside the stream is therefore being filtered less efficiently at the initial smoking -11period, where it is being filtered more and more efficiently due to this gradual increase in the filtration efficiency as the smoke process proceeds. The tar concentration of the last few puffs is therefore very much reduced. Consequently a cigarette fitted with this filter has a much more even satisfying tar delivery and it is therefore possible to arrange the dimensions of the filter to co-operate with the construction of the two part cigarette rod so that a substantially uniform strength of smoke flavour and aroma are provided .

The combination of this type of filter and the two part tobacco construction of the filter rod has thus enabled this to be achieved, the particular effect of the filter complementing the two part rod.

Figure 2 shows a cigarette rod construction in which the zone of stronger tobacco 1 is wedge shaped and in Figure 3 the zone of stronger tobacco is conical. Figure 4 shows a construction in which the zone of stronger tobacco is frusto-conical. In all these constructions the milder tobacco 2 fills the remainder of the space in the rod.

These wedges , cones or frusto-cones of stronger tobacco are shown as extending throughout the whole length of the rod but, if desired they may only extend for a portion of the length.

In the construction shown in Figures 5, 6 and 7 the strong tobacco 1 occupies the whole of the tobacco rod cross-section for the first few millimetres of length from the kindled end 10. Such tobacco rods may be produced by the manufacturing process disclosed in European Patent Application No. 0 307 090 of Rothmans, Benson and Hedges Inc. and Rothmans International Services Limited. Other suitable configurations are also disclosed in this European -12Patent Application.

The material forming the blend of strong tobacco may include cured and aged flue-cured, Burley, Maryland or Oriental tobaccos or rare speciality tobaccos such as Latakia or fire-cured tobaccos. If desired, expanded tobacco or minor amounts or reconstituted tobacco sheet , processed stems or tobacco substitutes may be incorporated.

The material forming the milder blend of tobaccos may also include flue-cured, Burley, Maryland or Oriental tobaccos or rare speciality tobaccos but, in general, it is advantageous when at least a proportion of these are milder varieties. Other materials used in this milder blend may include expanded tobaccos, reconstituted tobaccos, processed stems or tobacco substitutes and these materials may form a major portion of the blend.

As mentioned above the filter which is attached to the end of the tobacco rod containing the higher proportion of milder tobaccos and which has the special property of increasing in filtration efficiency puff-by-puff during the smoking of the cigarette can be as' described in European Patent Application 88308323.0 (Publication No. 0 310 257) and the filter shown in Figure 7 is of another type also described in that Patent Application. In this construction the tube 5 as shown in Figures 1 to 6 is replaced by an impervious film tube 12. As in the case of tube 5, tube 12 contains aperture 7, closed end 14 and open end 15.

Aperture 7 is in flow communication between fibrous material 13 and fibrous material 11. Preferably, the fibrous material 11 is less densely packed than the fibrous material 13. Furthermore, the fibre diameter should be as large as feasible. For example, a commonly available cellulose acetate tow of between 5 to 15 denier per filament (dpf), -1310,000 to 50,000 total denier (T.D.) will be suitable. Material 13 should be a filtration material of high filtration efficiency. Preferably, material 13 will be the commonly used cellulose acetate tow such as the tow of about 1.5 dpf to 5 dpf and preferably 1.5 dpf to 3.5 dpf.

When a cigarette fitted with this filter is smoked, the smoke enters the filter rod where the closed end 14 is located. The smoke initially flows through material 13.

When it reaches the vicinity of aperture 7, the smoke splits into two streams; one stream of smoke continues to flow through material 13; the other stream flows through the aperture 7 and into material 11. Both streams flow out of the filter rod at the filter end where the open end 15 is located. The embodiment has an additional advantage to that shown in Figures 1 to 6. The main advantage is that material 11 in the vicinity of aperture 7 provides an additional means for the smoke particle to be captured by the mechanism of impaction as the smoke flows from aperture 7 into material 11. In fact, material 11 not only provides a filtration medium inside tube 12, it also provides an impacting surface for the smoke particles in the vicinity of aperture 7. It is well known that the velocity and momentum of the smoke particles will greatly increase when they flow through a narrow and restricted passage such as aperture 7. These conditions favour the capture of smoke particles by impaction on the fibres of material 11 which are transverse to the flow direction of the smoke in the vicinity of aperture 7. The captured smoke particles will gradually build up inside material 11 in the vicinity of aperture 7. This build-up will further improve the capture efficiency as the void volume there is reduced to a certain extent. The function of material 11 in the vicinity of aperture 7 has clearly enhanced the overall aim of a gradual increase in efficiency of the whole cigarette filter. Due to the novel -14idea of choosing the material 11 as a fibrous material of low packing density, ie of large void volume, and/or fibres of large diameter, the build-up of captured smoke particles will never be sufficient to clog up the flow passage between aperture 7 and open end 15 during the smoking period. The danger of greatly increased flow resistance in such flow passage is therefore avoided.

These types of filter as described in European Patent Application No. 88308323.0 (Publication No. 0 310 257) are especially effective if assembled to the tobacco rod in the reverse configuration with the open end of the tube in abutment with the tobacco.

In the construction shown in Figure 9 the filter is of the kind set forth in European Patent Application No. 89310430.7 (Publication No. 0 364 256). In this construction a filter rod is formed from an element which comprises a tube 24, a barrier disc 23 provided with an aperture 22 and made from a layer of micro-fine fibres between 0.5 to 10 microns diameter. The tube 24 may be of any convenient material such as paper or plastics material. The edge of disc 23 is in close contact with the inside wall of the tube 24 so that end-to-end flow path communication through the tube has to pass through disc 23. The aperture 22 can be a single aperture or up to ten apertures, between one and three apertures being preferred. A single aperture may be located conveniently at or around the centre of the disc. If multiple apertures are used, they may be spread evenly on the disc or around the centre, and each individual aperture may be different in size and shape to the others. The disc may be made of a plurality of layers of fibres, at least one layer being of micro-fine fibres of 0.5 to 10 microns in diameter. -15The aperture or apertures act as a flow opening and are 0.1 mm to 3.0 mm in diameter with a combined total opening 2 2 area of 0.1 mm to 10 mm . The layer of micro-fine fibres has a packing density of 0.05 to 0.3 and the thickness of said layer is between 0.5 mm and 4 mm.

The advantages of this type of filter construction are set out in the specifications referred to and provide a more even puff-by-puff tar delivery profile. The present invention takes advantage of this filter characteristic to enable an even smoke to be provided by using the multi-part cigarette rod construction.

Figure 11 shows another alternative construction of the kind set forth in European Patent Application No. 89310421.6 (Publication No. 0 364 253). In this construction the filter element comprises a barrier tube 31, an outer tube in the form of a plug wrap 33 and the space between the tube 31 and the plug wrap 33 being filled with a porous material 34 such as cellulose acetate tow, or polypropylene tow, polymeric foam materials or any suitable granular materials, apertures can be provided if desired at any convenient location. One end of the tube is blocked for gas flow as indicated by reference numeral 36.

The tube 31 is made from a layer of micro-fine fibres between 0.5 to 10 microns in diameter of a plurality of filters of fibres, at least one layer being of micro-fine fibres of 0.5 to 10 microns in diameter. The fibres have a packing density of 0.05 to 0.3 and the thickness of the layers between 0.5 mm and 2 mm.

The barrier tube 31 is wrapped around a core 38 made of porous material, preferably with minimum flow resistance to gas flow. Commonly known filter materials such as the -16cellulose acetate or polypropylene tow may be used. Preferably the tow used may consist of a coarse fibre such as 5 denier per filament or larger. In addition the filter material should be packed with a low packing density.

As mentioned above apertures, similar to aperture 7 in Figures 1 to 8, can be provided as this prevents the microfine fibres in the tube becoming clogged, the flow openings allowing what is in effect a controlled leakage.

The advantages of this type of filter are set forth in the European Patent Specification referred to and it will be appreciated that in any of the other constructions described in that specification can be utilised in the present invention .

Filters disclosed in PCT Patent Application CA/90/00070 can also be used and the disclosure in that Patent Specification is incorporated herein. There are particular advantages with this type of filter as with the filter shown in Figures 11 and 12 in view of their high filtration efficiency. This high efficiency makes it possible to use very strong tobaccos in the region of the kindled end 10 of the cigarette without providing untoward levels of smoke to the smoker in the early puffs. Consequently differences in strength between the kindled end and the other end of the cigarette rod are able to be increased to promote the flattening of the puff-by-puff profile.

The use of demarcated zones of different tobaccos in the tobacco rod in conjunction with the filters of the kind set forth which provide progressive filtering, leads to a much more uniform puff-by-puff smoke delivery than in the case of either a cigarette with a standard type of filter but with different demarcated zones of different tobacco or -17cigarette filters of the kind set forth in the Patent Specifications referred to alone. Thus the present invention provides a particular advantageous effect by the combination of the special filters and the demarcated zone tobacco rod which produces a smokable cigarette which is much more acceptable to the smoker than would be expected.

Claims (23)

1. A cigarette or cigar comprising a rod of tobacco which decreases in strength from the kindled end to the other end and which is provided with a filter, the filtration efficiency of which increases as the cigarette is consumed .

2. A cigarette as claimed in claim 1 in which the tobacco rod comprises two or more different types or blends of tobacco separated into demarcated zones, the tobacco at the kindled end of the cigarette being higher in strength and/or quality and/or flavour and/or nicotine content than at the other end through which the smoke is drawn.

3. A cigarette as claimed in claim 2 in which the demarcated zones are in the form of segments, or the zone of stronger tobacco is wedge shaped, conical or frusto-conical.

4. A cigarette as claimed in claim 3 in which the wedges, cones or frusto-cones of stronger tobacco extend throughout substantially the whole length of the tobacco rod .

5. A cigarette as claimed in claim 2 in which a wedge, conical or frusto-conical shape is used over part of the length of the rod, the kindled end being wholly of the stronger tobacco.

6. A cigarette as claimed in claims 1 to 5 in which the material forming the blend of strong tobacco includes cured and aged flue-cured, Burley, Maryland or Oriental tobaccos, or rare speciality tobaccos. -197. A cigarette as claimed in claim 6 in which the rare speciality tobaccos include Latikia or fire-cured tobaccos.

7. 8. A cigarette as claimed in claim 6 or claim 7 in which the material forming the blend of strong tobaccos includes expanded tobacco or minor amounts of reconstituted tobacco sheet, processed stems or tobacco substitutes.

8. 9. A cigarette as claimed in claims 1 to 8 in which the milder blend of tobaccos include flue-cured, Burley, Maryland or Oriental tobaccos or rare speciality tobaccos of the milder varieties.

9. 10. A cigarette as claimed in claim 9 in which the milder blend of tobaccos include expanded tobaccos, reconstituted tobaccos, processed stems or tobacco substitutes.

10. 11. A cigarette as claimed in claim 10 in which the expanded tobacco, reconstituted tobacco processed stems or tobacco substitute form a majority part of the blend.

11. 12. A cigarette as claimed in claims 1 to 11 in which the filter comprises a filter element of fibrous material, the fibres of which extend longitudinally between a first end which is for attachment to the tobacco rod and a second end, and which surrounds a longitudinally extending tube member, one end of which is closed and is located at the first end of the filter element and the open end of which extends to the second end of the element, the wall of the tube being provided with one or more radially extending apertures adjacent to its closed end to promote radial flow through the fibres of the filter element adjacent the aperture or apertures and being dimensioned so that they remain open to allow flow communication through the wall· of the tube throughout the period that the cigarette is smoked. -2013. A cigarette as claimed in claim 12 in which said filter is assembled to the tobacco rod in the reverse configuration with the open end of the tube in abutment with the tobacco.

12. 14. A cigarette as claimed in claim 12 or claim 13 in which the interior of the tube is empty.

13. 15. A cigarette as claimed in claim 12 or claim 13 in which the interior of the tube is filled with a column of filter material.

14. 16. A cigarette as claimed in claim 12, claim 13, claim 14 or claim 15 in which the tube is formed by an impervious film .

15. 17. A cigarette as claimed in claims 1 to 11 in which the filter comprises a filter element having a flow path therethrough which includes a barrier in the form of a substantially planar disc made from a layer of micro-fine fibres with a diameter of between 0.5 and 10 microns, and provided with one or more flow openings in the range 0.1 mm to 3.0 mm in diameter with a combined total area of between 0.1 mm^ and 10 mm^ .

16. 18. A cigarette as claimed in claim 17 in which the disc is located between layers of porous material to form a laminate barrier.

17. 19. A cigarette as claimed in claims 1 to 11 in which the filter comprises a filter element which includes an axially extending barrier tube of micro-fine fibres with a diameter of between 0.5 and 10 microns and located so that at least part of the gas flow passes through the wall of the barrier. 2120. A cigarette as claimed in claim 19 in which said barrier tube is provided with one or more flow openings in the range of 0.1 mm to 3.0 mm in diameter with a combined 2 2 total area of between 0.1 mm and 10 mm .

18. 21. A cigarette as claimed in claim 19 or claim 20 in which said barrier tube is shaped to provide inner and outer co-axial passages through the filter element, one of which is closed at one end and the other of which is closed at the other end so that the flow path passes through the wall of the barrier tube.

19. 22. A cigarette as claimed in claim 21 in which the interior of the barrier tube is empty.

20. 23. A cigarette as claimed in claim 21 in which the interior of the barrier tube is filled with a column of filter material.

21. 24. A cigarette as claimed in claims 1 to 11 in which the filter comprises an annulus of conventional filter material surrounding a cylinder of micro-fine fibres , a smoke flow directing element ensuring that all the smoke drawn from the cigarette enters the annulus of conventional filter material and a low resistance filtered smoke path is provided at the interior of the cylinder of micro-fine fibres .

22. 25. A cigarette according to any preceding claim substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. Dated this the 12th day of July, 1990. F. R. KELLY & CO. BY ______ EXECUTIVE

23. 2 7 Clyde Roaji, Bailsbridge, Dublin 4. AGENTS FOR THE APPLICANTS. ROTHMANS INTERNATIONAL TOBACCO (UK) LIMITED 2 Sheets TRUE COPY Sheet 1 2 10 Fig. 6 KA. A Co, ROTHMANS INTERNATIONAL TOBACCO (UK) LIMITED 2 Sheets TRUE COPY Sheet 2 12 7 13 2 FlG.7