AEROSOL GENERATING ARTICLE WITH VENTILATION ZONE

Abstract

An aerosol generating article is provided, including a combustible heat source; an aerosol forming substrate downstream of the combustible heat source; and a wrapper circumscribing at least a rear portion of the combustible heat source and at least a front portion of the aerosol forming substrate, wherein a plurality of weakness formations are provided on a region of the wrapper overlying the combustible heat source, and wherein the wrapper is rupturable at the plurality of weakness formations and is configured to form a ventilation zone comprising a plurality of apertures extending through the wrapper.

Claims

1.-16. (canceled)

17. An aerosol generating article, comprising: a combustible heat source; an aerosol forming substrate downstream of the combustible heat source; and a wrapper circumscribing at least a rear portion of the combustible heat source and at least a front portion of the aerosol forming substrate, wherein a plurality of weakness formations are provided on a region of the wrapper overlying the combustible heat source, and wherein the wrapper is rupturable at the plurality of weakness formations and is configured to form a ventilation zone comprising a plurality of apertures extending through the wrapper.

18. The aerosol generating article according to claim 17, wherein at least one of the weakness formations is defined by one or more lines of weakness.

19. The aerosol generating article according to claim 17, wherein at least one of the weakness formations is defined by two or more intersecting lines of weakness.

20. The aerosol generating article according to claim 17, wherein the plurality of weakness formations are formed from a local reduction in thickness of the wrapper.

21. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a circumferential dimension of at least about 0.5 mm.

22. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a circumferential dimension of from about 0.5 mm to about 2.6 mm.

23. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a circumferential dimension of from about 0.8 mm to about 1.8 mm.

24. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a length of at least about 0.1 mm.

25. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a length of from about 0.1 mm to about 2.1 mm.

26. The aerosol generating article according to claim 17, wherein each weakness formation of the plurality of weakness formations has a length of from about 0.2 mm to about 1.8 mm.

27. The aerosol generating article according to claim 17, wherein adjacent weakness formations among the plurality of weakness formations are separated in a circumferential direction by a circumferential separation of at least about 0.5 mm.

28. The aerosol generating article according to claim 17, wherein adjacent weakness formations among the plurality of weakness formations are separated in a longitudinal direction by a longitudinal separation of at least about 0.4 mm.

29. The aerosol generating article according to claim 17, wherein the plurality of weakness formations are provided in a regular pattern.

30. The aerosol generating article according to claim 17, wherein the plurality of weakness formations are arranged such that the plurality of apertures have a total area of at least about 0.09 millimetres squared.

31. The aerosol generating article according to claim 17, wherein the weakness formations of the plurality of weakness formations are arranged such that the plurality of apertures form indicia on an outer surface of the wrapper.

32. The aerosol generating article according to claim 17, wherein the wrapper is formed from a heat conductive material.

33. The aerosol generating article according to claim 17, wherein the wrapper is substantially impermeable to air.

34. The aerosol generating article according to claim 17, wherein the wrapper circumscribes the combustible heat source along at least about 50 percent of a length of the combustible heat source.

35. The aerosol generating article according to claim 34, wherein the weakness formations of the plurality of weakness formations are provided on the wrapper such that a ventilation zone extends along at least about 50 percent of the length of the combustible heat source.

36. The aerosol generating article according to claim 17, wherein the wrapper is in direct contact with an outer surface of the combustible heat source.

Description

[0089] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0090] FIG. 1 shows a schematic longitudinal cross-sectional view of a first embodiment of smoking article according to the present invention;

[0091] FIGS. 2A and 2B show a schematic side perspective view of a multi-segment component of the smoking article of FIG. 1 having a wrapper with a plurality of weakness formations according to a first example;

[0092] FIG. 2C shows an enlarged view of the wrapper of the multi-segment component of FIGS. 2A and 2B;

[0093] FIG. 3 shows a schematic side perspective view of the smoking article of FIG. 1, in which the cap has been removed and the wrapper is ruptured to form a ventilation zone;

[0094] FIG. 4A shows an enlarged view of a wrapper for the smoking article of FIG. 1, the wrapper having a plurality of weakness formations according to a second example;

[0095] FIG. 4B shows an enlarged view of the wrapper of FIG. 4A in which the wrapper is ruptured at the weakness formations to form a ventilation zone.

[0096] The smoking article 100 according to the first embodiment of the invention shown in FIG. 1 comprises a combustible heat source 102, an aerosol-forming substrate 104, a transfer element 106, an aerosol-cooling element 108, a spacer element 110 and a mouthpiece 112 in abutting coaxial alignment. The combustible carbonaceous heat source 102 has a front end face 114 and an opposed rear end face 116. As shown in FIG. 1, the combustible heat source 102, aerosol-forming substrate 104, transfer element 106, aerosol-cooling element 108, spacer element 110 and mouthpiece 112 are wrapped in an outer wrapper 118 of sheet material such as, for example, cigarette paper.

[0097] The combustible heat source 102 is a blind carbonaceous combustible heat source and is located at the distal end of the smoking article 100. As shown in FIG. 1, a non-combustible substantially air impermeable barrier 120 in the form of a disc of aluminium foil is provided between the rear end face 116 of the combustible carbonaceous heat source 102 and the aerosol-forming substrate 104. The barrier 120 is applied to the rear end face 116 of the combustible heat source 102 by pressing the disc of aluminium foil onto the rear end face 116 of the combustible heat source 102. The barrier 120 and abuts the rear end face 116 of the combustible carbonaceous heat source 102 and the aerosol-forming substrate 104.

[0098] The aerosol-forming substrate 104 is located immediately downstream of the barrier 120 applied to the rear end face 116 of the combustible carbonaceous heat source 102. As shown in FIG. 1, the combustible heat source 102 and the aerosol-forming substrate 104 are in abutting coaxial alignment. The aerosol-forming substrate 104 comprises a cylindrical plug of homogenised tobacco-based material 122 including an aerosol former such as, for example, glycerine, wrapped in plug wrap 124.

[0099] The transfer element 106 is located immediately downstream of the aerosol-forming substrate 104 and comprises a cylindrical open-ended hollow cellulose acetate tube 128.

[0100] The aerosol-cooling element 108 is located immediately downstream of the transfer element 106 and comprises a gathered sheet of biodegradable polymeric material such as, for example, polylactic acid.

[0101] The spacer element 110 is located immediately downstream of the aerosol-cooling element 108 and comprises a cylindrical open-ended hollow paper or cardboard tube.

[0102] The mouthpiece 112 is located immediately downstream of the spacer element 110. As shown in FIG. 1, the mouthpiece 112 is located at the proximal end of the smoking article 100 and comprises a cylindrical plug of suitable filtration material 130 such as, for example, cellulose acetate tow of very low filtration efficiency, wrapped in filter plug wrap 132. The smoking article 100 may further comprise a band of tipping paper (not shown) circumscribing a downstream end portion of the outer wrapper 118.

[0103] As shown in FIG. 1, the smoking article 100 further comprises a wrapper 126 circumscribing at least a rear portion of the combustible heat source 102 and at least a front portion of the aerosol forming substrate 104. The wrapper 126 is wrapped tightly around the combustible heat source 102 and the aerosol forming substrate 104 to maintain the correct position of the combustible heat source 102 relative to the aerosol forming substrate. In this example, the wrapper 126 is formed from a heat conductive material such as, for example, aluminium foil, such that it forms a heat conducting element. Thus, the wrapper 126 forms a thermal bridge between the combustible heat source 102 and the aerosol forming substrate to ensure sufficient conductive heat transfer from the combustible heat source 102 to the aerosol forming substrate 104. The wrapper 126 is substantially impermeable to air. Consequently, the wrapper 126 forms a barrier prior to rupture, for example to restrict the amount of moisture absorbed from the atmosphere by the combustible heat source 102 during transportation and storage. As moisture may hinder the heating performance of the heat source, restricting the amount of moisture absorbed by the heat source may have a positive impact on the performance of the smoking article 100. In other examples, the wrapper 126 may be formed from a heat insulative sheet material such as, for example, cigarette paper, of low air permeability, which is wrapped around the combustible heat source 102 and the aerosol-forming substrate 104.

[0104] In this example, the wrapper 126 overlies the entire length of the combustible heat source 102, with the exception of a front portion adjacent to the front end face 114 of the combustible heat source 102, and the entire length of the aerosol-forming substrate 104. In other embodiments of the invention (not shown), the aerosol-forming substrate 104 may extend beyond the heat-conducting element 126 in the downstream direction. That is the wrapper 126 may overlie only a front portion of the aerosol-forming substrate 104. It will be appreciated that in other embodiments of the invention (not shown), one or more additional heat-conducting elements may be provided that overlie the wrapper 126.

[0105] In this example, the smoking article 100 further comprises a removable cap 134 at its distal end and directly adjacent to the heat source 102. For example, the removable cap may comprise a central portion including a desiccant, such as glycerine, to absorb moisture as compared to the heat source, which is wrapped in a portion of the outer wrapper 118 and connected to the rest of the outer wrapper 118 along a line of weakness 136 comprising a plurality of perforations in the outer wrapper that circumscribe the smoking article. To use the smoking article, the user removes the removable cap 134 by transversely compressing the cap by pinching it between thumb and finger. By compressing the cap, sufficient force is provided to the line of weakness 136 to locally break the outer wrapper 118. The user then removes the cap by twisting the cap to break the remaining portion of the line of weakness. When the cap is removed, the front portion of the combustible heat source 102 is exposed which enables the user to light the smoking article 100.

[0106] The smoking article 100 comprises one or more air inlets 138 around the periphery of the aerosol-forming substrate 104. As shown in FIG. 1, a circumferential arrangement of air inlets 138 is provided in the plug wrap 126 of the aerosol-forming substrate 104 and the overlying outer wrapper 120 to admit cool air (shown by dotted arrows in FIG. 1) into the aerosol-forming substrate 104.

[0107] In use, the user removes the cap 134 and ignites the combustible heat source 102, which heats the aerosol-forming substrate 104 to produce an aerosol. When the user inhales on the mouthpiece 110, air (shown by dotted arrows in FIG. 1) is drawn into the aerosol-forming substrate 104 through the air inlets 138.

[0108] The front portion of the aerosol-forming substrate 104 is heated by conduction through the rear end face 116 of the combustible carbonaceous heat source 102, through the barrier 120 and through the wrapper 126 which acts as a heat conducting element.

[0109] The heating of the aerosol-forming substrate 104 by conduction releases glycerine and other volatile and semi-volatile compounds from the plug of homogenised tobacco-based material 122. The compounds released from the aerosol-forming substrate 104 form an aerosol that is entrained in the air drawn into the aerosol-forming substrate 104 of the smoking article 100 through the air inlets 138 as it flows through the aerosol-forming substrate 104. The drawn air and entrained aerosol (shown by dashed arrows in FIG. 1) pass downstream through the interior of the cylindrical open-ended hollow cellulose acetate tube 128 of the transfer element 106, the aerosol-cooling element 108 and the spacer element 110, where they cool and condense. The cooled drawn air and entrained aerosol pass downstream through the mouthpiece 112 and are delivered to the user through the proximal end of the smoking article 100. The non-combustible substantially air impermeable barrier 120 on the rear end face 116 of the combustible heat source 102 isolates the combustible heat source 102 from air drawn through the smoking article 100 such that, in use, air drawn through the smoking article 100 does not come into direct contact with the combustible heat source 102.

[0110] FIGS. 2A and 2B show a schematic side perspective view of a multi-segment component 140 of the smoking article 100 of FIG. 1. The multi-segment component 140 comprises the combustible heat source 102, aerosol forming substrate 104 and wrapper 126 of the smoking article 100 of FIG. 1. FIG. 2A shows the wrapper 126 circumscribing the combustible heat source 102 and the aerosol forming substrate 104. FIG. 2B shows the wrapper 126 as partially unravelled to allow the combustible heat source 102 and the aerosol-forming substrate 104 to be viewed.

[0111] The multi-segment component 140 may be pre-assembled separately to the remaining components of the smoking article for subsequent assembly, or may be manufactured and assembled together with one or more other components of the smoking article 100.

[0112] As shown in FIGS. 2A and 2B, a plurality of weakness formations 150 according to a first example are provided on a weakness region 160 of the wrapper 126 overlying the combustible heat source 102. The wrapper 126 is rupturable at the weakness formations 150 to form a ventilation zone corresponding to the weakness region 160. The weakness formations 150 are arranged in a regular pattern of aligned rows and columns on the wrapper 126 and do not extend through the thickness of the wrapper.

[0113] FIG. 2C shows an enlarged view of the wrapper 126 of the multi-segment component 140. In this example, the weakness formations 150 are each defined by a plurality of lines of weakness 152 extending from a central unweakened region 154. The lines of weakness 152 are oblique to the longitudinal direction of the multi-segment component 140. In this example, each weakness formation 150 is shown as including lines of weakness 152, the four lines being grouped into two pairs of collinear lines that are transverse to each other such that each weakness formation 150 is approximately X shaped. As the lines are of similar length, the weakness formations 150 will form approximately square shaped apertures upon rupture.

[0114] Although each weakness formation 150 is shown as being defined by four lines of weakness 152, it will be appreciated that one or more of the weakness formations may be formed from fewer or more than four lines of weakness. For example, one or more of the weakness formations may be formed from three or more lines of weakness extending from a central unweakened region. In other examples, one or more of the weakness formations may comprise two or more intersecting lines of weakness. In such examples, the lines of weakness may intersect towards either end of one or more of the lines of weakness. The intersecting lines of weakness may intersect at a central region of the weakness formation. In yet further examples, one or more weakness formations may be formed by one or more lines of weakness extending along the perimeter, or part of the perimeter, of the desired aperture shape.

[0115] Although the lines of weakness 152 are shown as being of similar length, in other examples, one or more of the lines of weakness may be of different length.

[0116] Adjacent weakness formations are separated in the circumferential direction by a circumferential separation 156 and in the longitudinal direction by a longitudinal separation 157. Preferably, the circumferential separation 156 is at least about 0.5 mm, preferably from about 0.5 mm to about 2.5 mm, more preferably from about 0.7 mm to about 1.5 mm. Preferably, the longitudinal separation 157 is at least about 0.4 mm, preferably from about 0.4 mm to about 1.8 mm, more preferably from about 0.5 mm to about 1.3 mm.

[0117] Each weakness formation has a circumferential dimension 158 and a length 159. Preferably, the circumferential dimension 158 is at least about 0.5 mm, preferably from about 0.5 mm to about 2.6 mm, more preferably from about 0.8 mm to about 1.8 mm. Preferably, the length 159 is at least about 0.1 mm, preferably from about 0.1 mm to about 2.1 mm, more preferably from about 0.2 mm to about 1.8 mm.

[0118] The weakness formations 150 are arranged so that the resulting plurality of apertures has a total aperture area which is sufficient to allow sufficient supply of air to the combustible heat source 102 and to allow sufficient venting of combustion gases from the combustible heat source 102. Preferably, the weakness formations 150 are arranged so that the resulting plurality of apertures has a total aperture area of at least about 0.09 millimetres squared, preferably from about 0.09 millimetres squared to about 40 millimetres squared, more preferably from about 0.4 millimetres squared to about 30 millimetres squared.

[0119] During use of the smoking article 100, pressure exerted on the wrapper 126 by combustion gases released by the combustible heat source 102 causes the wrapper 126 to rupture at the weakness formations 150 to form a ventilation zone comprising a plurality of apertures extending through the wrapper 126, as discussed below in relation to FIG. 3.

[0120] FIG. 3 shows a schematic side view of the smoking article 100 during use. As shown, the cap has been removed from the upstream end of the smoking article to allow the combustible heat source 102 to be lit by the user at its upstream end. When lit, the combustible heat source 102 generates heat and combustion gases which exert pressure on the wrapper 126. This causes the wrapper 126 to rupture at the weakness formations to form a ventilation zone 180 comprising a plurality of apertures 170 extending through the wrapper 126, with each aperture 170 corresponding to a weakness formation in the wrapper.

[0121] Due to the presence of the ventilation zone 180, the supply of air to the combustible heat source may be sufficient despite tight wrapping of the wrapper 126 around the combustible heat source 102. This ensures that there is no significant adverse effect on the amount of heat generated by the combustible heat source 102 during use, despite the extent to which the combustible heat source 102 is covered by the wrapper 126. The ventilation zone 180 also allows combustion gases generated by the combustible heat source 102 to escape through the plurality of apertures 170. This prevents a build up of excessive pressure behind the wrapper 126 which may, given the amount of the combustible heat source 102 which is covered by the wrapper 126, lead to a radial gap being formed between the wrapper 126 and the combustible heat source 102, which could in turn lead to relative movement between the combustible heat source 102 and the aerosol forming substrate 104. The ventilation zone 180 thus ensures that the heat generation by the combustible heat source 102, the conductive heat transfer from the heat source 102 to the aerosol forming substrate 104, and consequently the performance of the smoking article, is maintained, despite the extent to which the combustible heat source 102 is covered by the wrapper 126.

[0122] As shown in FIG. 3, the combustible heat source 102 has a diameter 190 and extends upstream of the upstream end of the wrapper 126 by an amount 192. The wrapper 126 extends upstream of the outer wrapper 118 by an amount 194 and is overlapped at its downstream by the outer wrapper 118 by an amount 196. Example ranges for dimensions 190, 192, 194 and 196 are shown below in Table 1.

TABLE-US-00001 EXAMPLE PREFERRED DIMENSION DIMENSION RANGE DIMENSION RANGE 190 5-12 mm 7-8.1 mm 192 0-4 mm 1-2 mm 194 4-11 mm 5-8 mm 196 1-5 mm 2-4 mm

[0123] FIG. 4A shows an enlarged view of an alternative wrapper 426 for the smoking article 100 of FIG. 1, the wrapper 426 having a plurality of weakness formations according to a second example. As shown in FIG. 4A, each weakness formation 450 comprises a circumferential line of weakness 452 and a longitudinal line of weakness 453 intersecting at a central region 454. The weakness formations 450 are arranged in a regular pattern of evenly spaced rows, with adjacent rows being longitudinally offset and alternate rows being longitudinally aligned. It will be appreciated that other patterns of weakness formation are also envisaged.

[0124] Adjacent weakness formations 450 in longitudinally aligned alternate rows are separated in the circumferential direction by a circumferential separation 456. Adjacent weakness formations 450 in each row are separated in the longitudinal direction by a longitudinal separation 457. Preferably, the circumferential separation 456 is at least about 0.5 mm, preferably from about 0.5 mm to about 2.5 mm, more preferably from about 0.7 mm to about 1.5 mm. Preferably, the longitudinal separation 457 is at least about 0.4 mm, preferably from about 0.4 mm to about 1.8 mm, more preferably from about 0.5 mm to about 1.3 mm

[0125] Each weakness formation 450 has a circumferential dimension 458 and a length 459. As the weakness formations 450 are each formed by a circumferential line of weakness 452 and a longitudinal line of weakness 453, the circumferential dimension 458 corresponds to the circumferential length of the circumferential line of weakness 452 and the longitudinal dimension 459 corresponds to the length of the longitudinal line of weakness 453. Preferably, the circumferential dimension 458 is at least about 0.5 mm, preferably from about 0.5 mm to about 2.6 mm, more preferably from about 0.8 mm to about 1.8 mm. Preferably, the length 459 is at least about 0.1 mm, preferably from about 0.1 mm to about 2.1 mm, more preferably from about 0.2 mm to about 1.8 mm.

[0126] FIG. 4B shows an enlarged view of the wrapper 426 of FIG. 4A in which the wrapper 426 has ruptured at the plurality of weakness formations to form a ventilation zone 480 comprising a plurality of apertures 470 through the wrapper 426. As shown, due to the arrangement of the weakness formations, the plurality of apertures 470 are approximately diamond shaped and the ruptured portions 472 of wrapper have remained attached to the wrapper 426. This avoids the creation of debris from the wrapper 426.

[0127] The specific embodiments and examples described above illustrate but do not limit the invention. It is to be understood that other embodiments of the invention may be made and the specific embodiments and examples described herein are not exhaustive.