AU2008337827A1 - Recessed ventilation for smoking articles - Google Patents

Description

WO 2009/077244 PCT/EP2008/064343 TITLE OF THE INVENTION RECESSED VENTILATION FOR SMOKING ARTICLES 5 BACKGROUND OF THE INVENTION The present invention relates to the provision of recessed ventilation for smoking articles. Conventionally, smoking articles such as cigarettes comprise a tobacco rod in the form of a cylinder 10 of tobacco or tobacco-based material wrapped in a paper wrapper, which may be provided with a filter unit. In its basic form, the filter unit is a cylindrical element formed from acetate tow, optionally including features to modify the smoke flow and filter function, such as recesses and gaps, and additives such as particulate carbon. The tow may be wrapped in a layer of plug wrap or filter wrap, which is commonly porous. The filter unit is joined to the tobacco rod using a tipping 15 paper, which is an outer paper layer wrapped around the filter unit and overlapping the join between the filter unit and tobacco rod. The tipping paper is glued in place. The tipping paper is generally non-porous. Often, it is desired to dilute the smoke delivered to the smoker from the burning tobacco rod. This can be achieved by providing ventilation in the filter 20 unit, comprising apertures (holes) or perforations in the tipping paper. When the smoker draws on the lit smoking article, air enters the filter unit through the ventilation holes and mixes with the smoke as it passes through the filter unit, thereby diluting the smoke before it reaches the smoker. The ventilation holes are arranged in a circumferential zone comprising one or more rows of holes. They may be pre-perforated in the tipping paper before the tipping paper is applied to the filter unit 25 and tobacco rod, or may be made after the smoking article is assembled using on-line perforation, in which a focused laser beam is used to burn small holes through the tipping paper. The position, arrangement and quantity of ventilation holes may be carefully selected by the smoking article manufacturer to achieve a particular filtering and dilution effect, resulting in a 30 specific smoking experience. It is therefore desirable that the ventilation remain fully operable throughout smoking of the smoking article. However, the smoker may inadvertently or deliberately WO 2009/077244 PCT/EP2008/064343 2 cover one or more of the ventilation holes with his lips or fingers while smoking, and hence reduce the ventilation level below its intended amount. The normal methods of adding ventilation to cigarettes using either of the methods mentioned 5 above, namely pre-perforation (before the smoking article is assembled) or via laser (after the smoking article is assembled) result in ventilation levels that decrease with increasing flow through the cigarette. This change in ventilation with flow means that smoke yields can increase more than expected during puffing, and that the delivery of some volatile components in smoke, for example carbon monoxide (CO) are higher than expected. 10 The present invention seeks to address these problems. SUMMARY OF THE INVENTION 15 Accordingly, a first aspect of the present invention is directed to a smoking article comprising a tobacco rod, a filter unit having a circumferential ventilation zone, and a tipping paper joining the tobacco rod and the filter unit, at least one side of the ventilation zone being bounded by a circumferential element having a greater outer diameter than the outer diameter of the ventilation zone. 20 The circumferential element or elements provide a degree of protection for the ventilation zone by creating or defining a recess in which the ventilation zone is situated. A recessed ventilation zone, located below the surface of the surrounding parts of the filter unit, has a reduced chance of being blocked during smoking, because the surrounding raised ground makes it more difficult for the fingers or lips of the smoker to come into direct contact with the ventilating apertures of the 25 ventilation zone. Both deliberate and accidental covering of the ventilation zone is made more difficult or unlikely. The smoking article according to the invention exhibits a number of important advantages compared with smoking articles having conventional ventilation systems. Firstly, smoking articles according 30 to the invention allow a more consistent ventilation level to be maintained as flow (puff volume) increases, hence resulting in lower smoke yields than expected at puff volumes representative of WO 2009/077244 PCT/EP2008/064343 3 consumer smoking. Secondly, the flow upstream of the ventilation zone is reduced. This creates a greater residence time of smoke within the tobacco rod and enabling greater diffusion of key components, such as carbon monoxide, out of the tobacco rod. This also creates a greater residence time of smoke within the tobacco rod end of the filter and enabling greater adsorption / reduction of 5 key components via materials such as carbon held within the filter column. Thirdly, by adding an additional area of the cigarette where diffusion can occur, the level of components such as carbon monoxide can be reduced. In some embodiments, both sides of the ventilation zone may be bounded by a circumferential 10 element with a greater outer diameter. Two circumferential elements may be considered to best protect the ventilation zone, and barriers for both the lips and the fingers are thereby provided. For example, the circumferential elements may be formed by the tipping paper, the tipping paper being divided into two portions spaced apart by a circumferential gap that coincides with the 15 ventilation zone. This allows the invention to be implemented with no additional components beyond those of a conventional filter-tipped ventilated smoking article. Therefore, in a preferred embodiment, the smoking article of the present invention comprises a tobacco rod, a filter unit having a substantially circumferential ventilation zone, and a tipping paper, 20 the tipping paper being divided into two portions spaced apart by a substantially circumferential gap which defines the ventilation zone. In this embodiment, the gap preferably extends around the entire circumference of the smoking article, so that the tipping paper is completely divided into two portions either side of the gap. 25 However, embodiments wherein a narrow strip of tipping paper (or other material, eg plug wrap) extends across the gap thereby linking the two portions, though covering an area not sufficient to affect the above favourable ventilation properties of the smoking article, are also contemplated to be within the scope of the present invention. 30 The filter unit within the recessed ventilation zone may have an outer layer of plug wrap over which the tipping paper is provided. The plug wrap can be porous, in which case ventilation is achieved by WO 2009/077244 PCT/EP2008/064343 4 using the natural porosity of the material of the plugwrap to provide the permeability. This permeability may be increased by providing one or more apertures (eg perforations) in the plug wrap in the gap between the two portions of the tipping paper. This may be achieved in a conventional manner: for example, by making perforations in the plug wrap before the smoking article is 5 assembled (e.g. by pre-perforation of the filter wrap material or using pre-perforation of the filter rod), or by making perforations using a focused laser beam after the smoking article is assembled. Alternatively, the plug wrap may be non-porous. In this case, ventilation may be provided by one or more apertures (eg perforations) in the plug wrap in the gap between the two portions of the tipping 10 paper. This may be similarly be achieved in a conventional manner: for example, by making perforations in the plug wrap before the smoking article is assembled (e.g. by pre-perforation of the filter wrap material or using pre-perforation of the filter rod), or by making perforations using a focused laser beam after the smoking article is assembled. 15 In alternative embodiments, the filter covering may be any wrapping material suitable to effectively wrap the filter. In an alternative embodiment, the filter material may be non-wrapped. The level of ventilation achieved may be controlled by the width to the gap in conjunction with the permeability for naturally porous materials, or by the level of pre-perforation used for non-porous 20 materials, or by a combination of the gap and the level of pre-perforation for naturally porous materials. Typically, the perforations have a diameter in the range from 0.05 to 1.0 mm. Preferably, the gap has a width in the range from 1 to 20 mm, more preferably in the range from 1 to 15 mm. The precise gap width depends on various factors, such as the filter length and the degree of 25 ventilation desired. In one embodiment, the gap width is in the range 2-75%, preferably 5-60% of the length of the filter. For a conventional filter of length 27 mm, using a minimum mouth end tipping section of 8 mm and a minimum joining section at the tobacco rod end of 4 mm (4 mm overlap of the filter), would preferably result in a maximum gap of 15mm. 30 The arrangement where the plug wrap is porous, and the ventilation is provided primarily by the permeability of the plug wrap and the gap between the two portions of the tipping paper is an WO 2009/077244 PCT/EP2008/064343 5 approach wholly distinct from that of conventional ventilation holes in the tipping paper. The ventilation level can be tailored by choosing the width of the gap in conjunction with the permeability of the plug wrap, giving greater and finer control over the total ventilation provided, and also giving different ventilation effects from those of standard ventilation holes in tipping paper. 5 However, holes may be used to supplement the ventilation, giving further flexibility in designing ventilation. Hence, additionally, the ventilation zone may further comprise one or more apertures (eg perforations) in the plug wrap in the gap between the two portions of the tipping paper. A further aspect of the present invention is to apply additional material to either or both ends of the 10 split tipping. This arrangement is particularly advantageous in that it deepens the recess where ventilation occurs, making ventilation blocking even more difficult. Therefore, the invention provides in one embodiment a smoking article as described above, either in its broadest aspect or a preferred aspect, having a further circumferential element with a greater 15 outer diameter, the circumferential element being divided into two parts disposed either side of the ventilation zone. In an alternative embodiment, the invention provides a smoking article as described above, either in its broadest aspect or a preferred aspect, having a further circumferential element with a greater 20 outer diameter, the circumferential element extending from the mouth end of the smoking article towards the ventilation zone. Preferably, such a circumferential element extends partially over the ventilation zone to thereby overlap with the ventilation zone (partially covering the gap). 25 Suitably, the circumferential element described above comprises a web material, which may be of paper or fabric, and is preferably an outer paper wrapper applied over the tipping paper. The outer paper wrapper applied over the tipping paper may extend from the mouth end of the smoking article 30 to the ventilation zone. The thickness of the outer wrapper defines the height of the barrier/depth of the recess, and can be chosen accordingly. Preferably, the outer paper wrapper has a thickness equal WO 2009/077244 PCT/EP2008/064343 6 to or greater than the thickness of the tipping paper. The outer paper wrapper may have a thickness substantially one to ten times the thickness of the tipping paper. The ventilation zone may comprise one or more perforations in the tipping paper. 5 A yet further aspect of the invention is to use additional wrapping material at either or both ends of the split tipping such that the additional layer overlaps the recessed ventilation zone. In this case, the overlap is not adhered to the filter or filter wrap in the recess and provides additional protection for potential blocking. 10 Further, the ventilation zone may be provided in a circumferential groove in the filter unit. A groove allows the difference in the surface diameters of the ventilation zone and the circumferential elements to be increased further, hence providing a deeper recess and more protection for the ventilation zone. One or more grooves may be provided. The or each groove may be provided in a longitudinal or transverse direction. 15 In still further embodiments, the or each circumferential element may comprise a ridge extending above the surface of the tipping paper. This offers circumferential elements that are confined to the neighbourhood of the ventilation zone, which gives an appearance and feel that may be preferred by the smoker. 20 The ridge may comprise a band of material applied to the surface of the tipping paper. For example, the material may be paper or cardboard. Alternatively, the material may be a material that is applied as a liquid and which rapidly solidifies, such as a hot-melt adhesive. Alternatively, the ridge may be formed in and from the tipping paper. These various alternatives can be chosen accordingly to ease 25 or cost of manufacture, availability of materials, and the desired appearance and feel of the finished smoking article. Embodiments using ridges are readily adapted to provide a boundary or barrier on either side of the ventilation zone. Hence, both sides of the ventilation zone may be bounded by a ridge, or only one 30 side of the ventilation zone may be bounded by a ridge. The ventilation zone may comprise one or more perforations in the tipping paper.

WO 2009/077244 PCT/EP2008/064343 7 The outer circumference of the or each circumferential element may be 0.1-2mm greater than the outer circumference of the ventilation zone. Hence, the depth by which the ventilation zone is recessed below the adjacent surface of the filter unit can be chosen as desired, according to the level 5 of protection desired, and the appearance and feel of the completed smoking article. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention and to show how the same may be carried into effect 10 reference is now made by way of example to the accompanying drawings in which: Figs. 1 and la show a longitudinal and cross-sectional view of a conventional filter-tipped smoking article having a ventilation zone in its filter unit; Figs. 2, 2a, 3, 3a, 4 and 4a show longitudinal and cross-sectional views of examples of a first embodiment of the invention, in which a tipping paper divided into two portions is used to create a 15 protective recess for the ventilation zone; Figs. 5, 5a, 6 and 6a show longitudinal and cross-sectional views of examples of a further embodiment of the invention, in which additional material is added to one or both ends of the tipping paper divided into two portions hence creating a deeper recess; Figs. 7, 8, 9 and 10 show longitudinal and cross-sectional views of examples of a third embodiment 20 of the invention, in which one or more circumferential ridges are applied over the tipping at one or both boundaries of the ventilation zone; Fig. 11 is an ISO smoking data comparison graph for the split-tipping cigarettes of the present invention shown in Figs. 2 and 2a compared with an on-machine laser (OML)-ventilated control (with 2 standard deviation error bars: 950% confidence level); 25 Fig. 12 is an Intensive Smoking Data comparison graph for the split-tipping cigarettes of the present invention shown in Figs. 2 and 2a compared with an OML-ventilated control (with 2 standard deviation error bars: 95% confidence level); Fig. 13 is an Actual Ventilation vs Flow Comparison graph for the split-tipping cigarettes of the present invention shown in Figs. 2 and 2a compared with an OML-ventilated control; and 30 Fig. 14 is a Normalised Ventilation vs Flow Graph for the split-tipping cigarettes of the present invention shown in Figs. 2 and 2a compared with an OML-ventilated control.

WO 2009/077244 PCT/EP2008/064343 8 DETAILED DESCRIPTION Figures 1 and la show a longitudinal cross-sectional view through a conventional filter-tipped 5 smoking article such as a cigarette. The smoking article 10 comprises a cylinder of tobacco 12 wrapped in a paper wrapper 14 (cigarette paper), together forming a tobacco rod 15. A filter unit 16 is joined to one end of the tobacco rod 15. The filter unit 16 comprises a cylindrical core 18 made from acetate tow which is wrapped in a layer of plug wrap or filter wrap 20, which may be porous. The plug wrap 20 maintains the shape and structure of the core 18, in particular for multi-segment 10 filters which comprise two or more cylindrical segments of different structure and/or composition arranged longitudinally. A tipping paper 22 is wrapped around the filter unit 16 such that it overlaps the end of the tobacco rod 15; this joins the filter unit 16 and the tobacco rod 15 together to form the complete smoking article 10. The filter unit 16 is provided with a ventilation zone 24 comprising a circumferential ring of ventilation holes 26 in the tipping paper 22 (illustrated more clearly in Fig. 15 1 a). The holes 26 may be pre-perforated in the tipping paper before it is applied around the filter unit 16 and the tobacco rod 15. Alternatively, the holes 26 may be made after the smoking article 10 is assembled, using a focussed laser beam in an on-line perforation machine to burn through the tipping paper 22 (and also a small distance into the plug wrap 20 and core 18). 20 As can be appreciated from Figure 1, the ventilation zone is completely exposed, and is thus liable to be deliberately or accidentally covered or blocked (wholly or partially) by the lips or fingers of a smoker consuming the smoking article. The present invention proposes to address this problem by providing a ventilation zone that is 25 protected in a recess. By having the surface of the ventilation zone lower than the surrounding surface and in preferred embodiments, having a very wide area over which the ventilation is applied such that the likelihood of the ventilation being blocked is reduced. Figures 2 and 2a show a longitudinal and cross-sectional view of the filter unit end of a smoking 30 article according to a first embodiment of the invention. In this example, a circumferential element is provided around the filter unit on each side of the ventilation zone. The smoking article 10 WO 2009/077244 PCT/EP2008/064343 9 comprises a tobacco rod 15 joined to a filter unit 16 having a plug wrap 20 by a tipping paper 22, as in the conventional smoking article of Figure 1. However, the tipping paper 22 is split around the smoking article 10 into two portions 22A and 22B. The portions 22A, 22B are spaced apart by a circumferential gap 28, which provides the ventilation zone. Thus, the ventilation zone 24 is not 5 covered by the tipping paper 22. One portion 22A is a downstream portion, extending from the mouth end of the filter unit to the downstream boundary of the ventilation zone 24. The other portion 22B is an upstream portion, extending between the upstream boundary of the ventilation zone 24 to a position overlapping the tobacco rod 15, to hold the tobacco rod 15 to the filter unit 16. Thus, the two portions 22A, 22B of the tipping paper 22 form the cylindrical elements that bound 10 the ventilation zone 24. The ventilation zone 24 comprises a plug wrap 20 which is porous, or may have no filter plug wrap at all. Thus, ventilating air enters the core 18 of the filter unit 16 through the naturally occurring holes 26 in the plug wrap 20 or directly into the filter 16, via the gap 28 in the tipping paper 22, as shown by arrows A. Volatile components in smoke, such as carbon monoxide, diffuse out of the core in the opposite direction as shown by arrows B. The plug wrap 20 15 must therefore be porous, so that the ventilation is provided wholly naturally. This provides a unique ventilating arrangement, in which the ventilation level is determined by the combination of the porosity of the plug wrap 20 and the width of the gap 28 in the tipping paper 22. These two factors can be varied to provide any desired amount of ventilation, by a mechanism 20 distinct from the conventional hole-based method of ventilation. For example, a ventilation level of approximately 10% can be achieved using a plug wrap with a permeability of 50 Coresta Units (CU) and a 5 mm gap. The same gap size with a 200 CU plug wrap gives approximately 20% ventilation. A 10mm gap with a 200 CU plug wrap gives approximately 25 80% ventilation. The gap may have a width in the range 1-20 mm, for example, with a width of 1-10 mm being preferred. However, the invention is not so limited, and other gap sizes may be employed. 30 A porous plug wrap forms a naturally permeable barrier around the filter core 18, and by combining this with a gap in the tipping paper, the ventilation is provided by a large area of ultrafine pores.

WO 2009/077244 PCT/EP2008/064343 10 This provides benefits over the conventional ventilation arrangement of discrete holes in the tipping paper. For example, it allows gases in the smokestream to diffuse out from the filter unit at the ventilation zone, and it creates a more even relationship between smoke flow and ventilation such that the change in smoke yield due to any change in the flow rate is minimised, as described in more 5 detail below. Figures 3 and 3a show a similar example to that of Figure 2, with a split or divided tipping paper 22 providing the circumferential elements. In this example, however, the plug wrap 20 is non-porous and has added ventilation holes 26 (see Fig. 3a), so that ventilating air enters the filter core 18 10 through the added ventilation holes. Further flexibility in tailoring the ventilation level can be achieved by combining the examples of Figures 2 and 3, so that the smoking article includes ventilation holes in a porous plug wrap arranged in the gap between the two portions of the split. The ventilation zone thus comprises both 15 ventilation holes and the width of the plug wrap exposed by the gap. In the above example or the example of Figure 3, the ventilation holes are conveniently made in the assembled smoking article using on-line laser perforation. However, pre-perforated plug wrap may alternatively be used as may be non-wrapped filter materials. 20 Figures 4 and 4a show a further example of a smoking article utilising a spilt tipping paper. The smoking article 10 comprises the same components as that shown in Figure 2 or 3, so that the ventilation zone 24 is provided by the gap 28 and the porosity of the plug wrap 20 and/or added ventilation holes. Additionally, the filter unit 16 has a circumferential groove 30 formed in it (in 25 both the core 18 and the plug wrap 20) at the location of the gap 28 between the two portions 22A, 22B of the tipping paper 20. This groove 30 further increases the difference in the outer diameters of the circumferential elements (tipping paper portions 22A, 22B) and the ventilation zone 24, by recessing the ventilation zone 24 below the surface of the filter unit 16 and hence decreasing the diameter of the ventilation zone 24. Thus, the vulnerability of the ventilation zone 24 to covering is 30 reduced further. A smoking article according to this embodiment may also include ventilation holes in the plug wrap, like those of Figure 3; in such a case the plug wrap may be porous or non-porous.

WO 2009/077244 PCT/EP2008/064343 11 The circumferential groove or recess 30 may have any depth, since any decrease in the diameter of the ventilation zone increases its protection from blocking. Example depths are in the range up to 3 mm, and are preferably in the range 1-2mm. The groove 30 may be made by using heated former on 5 the filter rods (pre-cigarette fabrication) or on the filter post manufacture or may be made using any of the standard grooving methods known. Figures 5 and 5a show a further example of a smoking article utilising a spilt tipping paper. The smoking article 10 comprises the same components as that shown in Figure 2, so that the ventilation 10 zone 24 is provided by the gap 28 and the porosity of the plug wrap. Additionally, the depth of recess (24) has been further enhanced by the addition of another layer of tipping paper at the mouth (32A) and/or the tobacco rod end (32B). Figures 6 and 6a show a further example of a smoking article utilising a spilt tipping paper. The 15 smoking article 10 comprises the same components as that shown in Figure 5, so that the ventilation zone 24 is provided by the gap 28 and the porosity of the plug wrap. Additionally, the additional tipping materials added to the mouth end (32) are extended over, but not adhered to, the recess so as to provide even further protection against blockage of ventilation. In alternative embodiments (not shown), the additional tipping materials may extend over the recess at the tobacco rod end, as well 20 as (or instead of) at the mouth end. Embodiments of the invention that include a split tipping paper can be fabricated with only minor modifications to the fabrication process for a conventional smoking article. The tipping paper can be applied using conventional apparatus for this process, either as a separate stage for each of the two 25 portions, or simultaneously using two appropriately sized rolls of tipping paper spaced apart on a single dispenser by a distance corresponding to the intended width of the gap. As mentioned above, ventilation holes in the plug wrap (if included) can be pre-perforated or made on-line after the smoking article is wholly or partly assembled. 30 Figure 7 show an example of a smoking article according to another embodiment. Again, the smoking article 10 comprises a tobacco rod 15 joined to a filter unit 16 by a tipping paper 22 having WO 2009/077244 PCT/EP2008/064343 12 a ventilation zone 24 comprising one or more rings of ventilation holes 26 (pre-perforated or made on-line by laser). A plug wrap may be included in the filter unit 16. The smoking article 10 differs from a conventional smoking article such as that of Figure 1 in that it further comprises two circumferential ridges 34 disposed around the filter unit 16, over the tipping paper 22. There is one 5 ridge 34A on the downstream side of the ventilation zone 24, and one ridge 34B on the upstream side of the ventilation zone 24. The ridges 34 provide the circumferential elements with a greater diameter than that of the ventilation zone 24, which protect the ventilation zone 24 from being blocked. 10 The upstream ridge 34B provides a barrier or boundary that directs or guides the fingers of the smoker further upstream of the ventilation zone 24, so that the ventilation holes are not blocked. The downstream ridge 34A provides a barrier that inhibits the smoker from putting the filter unit 16 into his mouth by an amount that would produce blocking of the ventilation holes 26 by the lips. Also, the ridges 34 act together to make it more difficult to cover the ventilation holes 26 by deliberately 15 holding the smoking article over the ventilation zone, because the ridges 34 are close enough together to keep the fingers spaced above the underlying holes. The ridges 34 may be spaced apart by a distance in the range of 2-10mm, although the spacing will be chosen in part by reference to the width of the ventilation zone 24. Further, the height of the 20 ridges 34 may be in the range 0.2-2mm, for example Imm. Both ridges may be the same height, or ridges having different heights may be provided. The ridges may have widths in the range X-Y mm, and each ridge may have a different width. Dimensions outside the above example ranges may also be used. 25 In the example of Figure 7, the ridges 34 comprise bands of cardboard or paper that are applied over the tipping paper, and held in place by adhesive. The thickness of the cardboard or paper determines the height of the ridges 34, although more than one layers of cardboard or paper may be applied to increase the height. The bands may be applied to the tipping paper after the smoking article is assembled, for example using apparatus that wraps strips of material with pre-applied adhesive 30 around the filter unit. Alternatively, the ridge material can be stuck to the tipping paper before the tipping paper is used to assemble the smoking article, for example by applying continuous strips of WO 2009/077244 PCT/EP2008/064343 13 material to the tipping paper material before it is formed into the roll from which it is supplied to the assembly apparatus. Figure 8 show a similar example to that of Figure 7, but in this case the circumferential elements 5 comprise ridges 36A, 36B of a rapidly solidifying material, such as a hot-melt adhesive. This material is applied to the tipping paper in liquid form as a thin bead, which sets and hardens, bonding to the tipping paper as it does so. Each ridge may be applied separately, for example from two sequentially arranged nozzles on the production line, or a pair of appropriately spaced nozzles or other applicators may be used to apply both ridges simultaneously. The ridges can be applied to 10 the tipping paper after the smoking article is assembled. Alternatively, two beads of ridge material can be applied along the length of the tipping paper material before it is formed into a roll for use in the smoking article assembly apparatus. The ridge material may be applied to the tipping paper as a continuous bead to form an unbroken ridge. Alternatively, the ridges may be formed from a series of adjacent dots or lines of ridge material. 15 Figure 9 show a further example of an embodiment utilising ridges to protect the ventilation zone. In this example, the ridges 38A, 38B are integrally formed from the tipping paper, rather than being separate components applied to the tipping paper. The tipping paper has a pair of concertina folds, pleats or other suitable folds made in it before it is wrapped around the filter unit and the tobacco 20 rod to form the completed smoking article. The folded areas then stand proud of the surface of the tipping paper, to provide the ridges. Individual tipping papers may be folded before use, but it is more practical and efficient to form the folds in the continuous length of tipping paper that is then formed into a roll for supply to the assembly apparatus. The tipping paper may be pre-perforated, in which case a fold or folds is/are made on each side of the perforated zone. Alternatively, the 25 ventilation holes may be made on-line by laser after the tipping paper has been applied. Each of the examples of Figures 7, 8 and 9 include two spaced apart ridges so that the ventilation zone is bounded on both sides. However, a single ridge may alternatively be used, if this is likely to provide the desired amount of protection for the ventilation zone. The single ridge may be located 30 upstream of the ventilation zone, to inhibit blocking with fingers, or downstream of the ventilation zone to inhibit blocking with lips.

WO 2009/077244 PCT/EP2008/064343 14 Figure 10 show an example having a single ridge positioned downstream of the ventilation zone, and formed from a band of cardboard or paper stuck around the tipping paper like the ridges in Figure 7. 5 Example 1 A cigarette as shown in Figs. 2 and 2a having plug wrap filter and split cork tipping (gap width 10 mm) was prepared. 10 A standard ventilated product, having ventilation added by OML, was prepared as a control. The cigarette of the present invention and the control had the physical data / specification shown in Table 1. Bound Filter Pressure Pressure Sample Ventilation Density Drop Drop Paper Code % mm/cc mmWG mmWG OML 79.1 200 169.4 113 CP50-23VGM2.OKCW Control 1700 CU 80.0 200 169.4 113 CP50-23VGM2.OKCW Invention 2400 CU 84.9 200 169.4 113 CP50-23VGM2.OKCW Invention 15 Table 1 The ISO and Intensive Smoke Yields of the cigarettes of the present invention were compared with those of the controls. The results are shown in Tables 2 and 3 below and in Figs. 11 and 12. 20 Sample Regime NFDPM Nic CO CO:TAR Mg/cig mg/cig mg/cig OML Control ISO 1.4 0.14 1.0 0.71 1700 CU Split-Tipping ISO 1.6 0.16 0.9 0.56 2400 CU Split-Tipping ISO 1.1 0.08 0.5 0.45 WO 2009/077244 PCT/EP2008/064343 15 Table 2 In Table 2, the (ISO) smoking regime is as follows: 35/2/60 = 35cc puff/ 2 second duration, 60 second interval between puffs 5 The data in Table 2 show that the split tipping products of the present invention have a change in CO: tar ratio compared to the control.

WO 2009/077244 PCT/EP2008/064343 16 Sample Regime NFDPM Nic CO CO:TAR Mg/cig mg/cig mg/cig OML Control 60/2/30 7.4 0.77 6.6 0.89 1700 CU Split-Tipping 60/2/30 5.6 0.60 4.1 0.73 2400 CU Split-Tipping 60/2/30 3.7 0.40 2.2 0.59 Table 3 5 In Table 3, the (intense) smoking regime is as follows: 60/2/30 = 60cc puff/ 2 second duration, 30 second interval between puffs The data in Table 3 show that the tar yields are reduced for the split tip products, and the CO: tar ratios are again reduced at puffing conditions that are more representative of average consumer 10 smoking behaviour.

Claims (24)

1. A smoking article comprising a tobacco rod, a filter unit having a substantially circumferential ventilation zone, and a tipping paper joining the tobacco rod and the filter unit, at 5 least one side of the ventilation zone being bounded by a substantially circumferential element having a greater outer diameter than the outer diameter of the ventilation zone.

2. A smoking article according to claim 1, wherein the tipping paper is divided into two portions spaced apart by a substantially circumferential gap which defines the ventilation zone. 10

3. A smoking article according to claim 2, in which the gap has a width in the range 1-20 mm.

4. A smoking article according to claim 3, in which the filter unit has an outer layer of plug wrap over which the tipping paper is applied. 15

5. A smoking article according to claim 4, in which the plug wrap is porous.

6. A smoking article according to claim 4, in which the plug wrap is non-porous. 20

7. A smoking article according to claim 5 or claim 6, further comprising one or more apertures in the plug wrap in the gap between the two portions of the tipping paper.

8. A smoking article according to claim 7, in which the apertures comprise perforations made in the plug wrap before the smoking article is assembled. 25

9. A smoking article according to claim 7, in which the apertures comprise perforations made using a focussed laser beam after the smoking article is assembled.

10. A smoking article according to any one of claims 1 to 9, the filter unit further having a 30 substantially circumferential groove in the ventilation zone. WO 2009/077244 PCT/EP2008/064343 18

11. A smoking article according to any one of claims 1 to 10, having a further circumferential element with a greater outer diameter, the circumferential element being divided into two parts disposed either side of the ventilation zone. 5

12. A smoking article according any one of claims 1 to 10, having a further circumferential element with a greater outer diameter, the circumferential element extending from the mouth end of the smoking article towards the ventilation zone.

13. A smoking article according to claim 12, in which the circumferential element extends 10 partially over the ventilation zone.

14. A smoking article according to any one of claims 11 to 13, in which the circumferential element comprises an outer paper wrapper applied over the tipping paper.

15 15. A smoking article according to claim 14, in which the outer paper wrapper has a thickness equal to or greater than the thickness of the tipping paper.

16. A smoking article according to claim 15, in which the outer paper wrapper has a thickness substantially 1 to 10 times the thickness of the tipping paper. 20

17. A smoking article according to claim 1, in which the or each circumferential element comprises a ridge extending above the surface of the tipping paper.

18. A smoking article according to claim 17, in which the ridge comprises a band of material 25 applied to the surface of the tipping paper.

19. A smoking article according to claim 18, in which the material is paper, fabric or cardboard.

20. A smoking article according to claim 18, in which the material is a rapidly solidifying liquid. 30 WO 2009/077244 PCT/EP2008/064343 19

21. A smoking article according to claim 17, in which the ridge is formed in and from the tipping paper.

22. A smoking article according to any one of claims 17 to 21, in which both sides of the 5 ventilation zone are bounded by a ridge.

23. A smoking article according to any one of claims 17 to 21, in which only one side of the ventilation zone is bounded by a ridge. 10

24. A smoking article according to any one of claims 17 to 23, in which the ventilation zone comprises one or more perforations in the tipping paper.