Abstract
There is provided an aerosol generating article (2). The aerosol generating article comprises a combustible heat source (4) having a longitudinal outer surface, an aerosol-forming substrate (10) downstream of the combustible heat source, and a retaining wrap (35). The retaining wrap comprises a an upstream portion (31) extending at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source. The upstream portion of the retaining wrap comprises at least one opening (41, 42) overlaying at least about 30 percent of the longitudinal outer surface of the combustible heat source. The retaining wrap further comprises a downstream portion (33) circumscribing at least a portion of the aerosol-forming substrate.
Claims
1. An aerosol generating article comprising: a combustible heat source having a longitudinal outer surface; an aerosol-forming substrate downstream of the combustible heat source; and a retaining wrap comprising: an upstream portion extending at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source, and comprising at least one opening, the at least one opening overlaying at least about 30 percent of the longitudinal outer surface of the combustible heat source, and a downstream portion circumscribing at least a portion of the aerosol-forming substrate.
2. The aerosol generating article according to claim 1, wherein the upstream portion of the retaining wrap extends to the upstream end of the combustible heat source, or extends beyond the upstream end of the combustible heat source.
3. The aerosol generating article according to claim 1, wherein the at least one opening of the upstream portion of the retaining wrap has a total area of at least about 45 millimetres squared.
4. The aerosol generating article according to claim 1, wherein the upstream portion of the retaining wrap is adhered to the surface of the combustible heat source.
5. The aerosol generating article according to claim 1, wherein the retaining wrap comprises a metallic foil.
6. The aerosol generating article according to claim 1, wherein the retaining wrap comprises paper.
7. The aerosol generating article according to claim 6 wherein the paper comprises at least one of paper co-laminated with a metal or metalized paper.
8. The aerosol generating article according to claim 1, wherein the retaining wrap has a maximum thickness of no more than about 190 micrometres.
9. The aerosol generating article according to claim 1, wherein the at least one opening in the retaining wrap comprises an opening surrounded on all sides by the retaining wrap.
10. The aerosol generating article according to claim 9, wherein the upstream edge of the at least one opening is disposed at least about 1 millimetre from the upstream end of the combustible heat source.
11. The aerosol generating article according to claim 1, wherein the at least one opening extends to the upstream end of the retaining wrap such that the at least one opening in the retaining wrap is not surrounded on all sided by the retaining wrap.
12. The An aerosol generating article according to claim 1, wherein the upstream portion of the retaining wrap extends to the upstream end of the combustible heat source, the retaining wrap comprising both metallic foil, and paper co-laminated with a metal or metalized paper, and the at least one opening overlays between about 50 percent and about 90 percent of the longitudinal outer surface of the combustible heat source.
13. A method for forming an aerosol generating article, the method comprising: providing a combustible heat source and an aerosol-forming substrate, providing a portion of wrapping material, cutting at least one opening in the portion of wrapping material to form a retaining wrap, applying the retaining wrap to the combustible heat source and the aerosol-forming substrate such that, an upstream portion of the retaining wrap extends at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source, the at least one opening being in the upstream portion of the retaining wrap, the at least one opening overlays at least about 30 percent of the longitudinal outer surface of the combustible heat source, and a downstream portion of the retaining wrap circumscribes at least a portion of the aerosol-forming substrate.
14. The method according to claim 13, wherein the step of providing a portion of wrapping material comprises: providing a portion of paper co-laminated with a metal, or metallized paper; providing a portion of metallic foil; and affixing the portion of metallic foil to the portion of paper.
15. The method according to claim 14, wherein the step of cutting at least one opening in the portion of wrapping material comprises cutting a single opening through both; the portion of paper co-laminated with a metal, or metallized paper, and the portion of metallic foil.
Description
[0174] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:
[0175] FIG. 1 shows a schematic longitudinal cross-sectional view of an aerosol generating article according to the present invention.
[0176] FIG. 2 shows a perspective view of the upstream end of an aerosol generating article according to the present invention.
[0177] FIG. 3 shows a perspective view of the upstream end of a further aerosol generating article according to the present invention.
[0178] FIG. 4 shows a perspective view of the upstream end of a further aerosol generating article according to the present invention.
[0179] FIGS. 5 to 9 show schematic plan views of the upstream end of aerosol generating articles according to the present invention.
[0180] FIGS. 10 to 12 show temperature profiles for various smoking articles, including the smoking articles shown in FIGS. 5 to 9.
[0181] The aerosol generating article 2 according to the first embodiment of the invention is shown in FIG. 1. The aerosol generating article 2 comprises a blind combustible heat source 4 having a front face 6 and an opposed rear face 8, and an aerosol-forming substrate 10. The combustible heat source 4 is substantially cylindrical and comprises a longitudinal outer surface extending between the front face 6 and opposed rear face 8. The aerosol generating article 2 further comprises a transfer element 12 downstream of the aerosol-forming substrate 10, an aerosol-cooling element 14 downstream of the transfer element 12, a spacer element 16 downstream of the aerosol-cooling element 14, and a mouthpiece 18 downstream of the spacer element 16.
[0182] The blind combustible heat source 4 is a blind carbonaceous combustible heat source and is located at the upstream end of the aerosol generating article 2. As shown in FIG. 1, a non-combustible substantially air impermeable barrier 22 in the form of a disc of aluminium foil is provided between the rear face 8 of the blind combustible heat source 4 and the aerosol-forming substrate 10. The barrier 22 is applied to the rear face 8 of the blind combustible heat source 4 by pressing the disc of aluminium foil onto the rear face 8 of the blind combustible heat source 4 and abuts the rear face 8 of the combustible carbonaceous heat source 4 and the aerosol-forming substrate 10.
[0183] In other embodiments of the invention (not shown), the non-combustible substantially air impermeable barrier 22 between the rear face 8 of the blind combustible heat source 4 and the aerosol-forming substrate 10 may be omitted.
[0184] The aerosol-forming substrate 10 is located immediately downstream of the barrier 22 applied to the rear face 8 of the blind combustible heat source 4. The aerosol-forming substrate 10 comprises a cylindrical plug of homogenised tobacco-based material 24 including an aerosol former such as, for example, glycerine, wrapped in plug wrap 26.
[0185] The transfer element 12 is located immediately downstream of the aerosol-forming substrate 10 and comprises a cylindrical open-ended hollow cellulose acetate tube 28.
[0186] The aerosol-cooling element 14 is located immediately downstream of the transfer element 12 and comprises a gathered sheet of biodegradable polymeric material such as, for example, polylactic acid.
[0187] The spacer element 16 is located immediately downstream of the aerosol-cooling element 14 and comprises a cylindrical open-ended hollow paper or cardboard tube 30.
[0188] The mouthpiece 18 is located immediately downstream of the spacer element 16. As shown in FIG. 1, the mouthpiece 18 is located at the proximal end of the aerosol generating article 2 and comprises a cylindrical plug of suitable filtration material 32 such as, for example, cellulose acetate tow of very low filtration efficiency, wrapped in filter plug wrap 34.
[0189] As shown in FIG. 1, the aerosol generating article 2 further comprises a retaining wrap 35. The retaining wrap 35 comprises an upstream portion 31 which extends the full length of the combustible heat source 4 on the longitudinal outer surface of the combustible heat source 4. The upstream portion 31 of the retaining wrap 35 comprises a first 41 and second 42 opening. The first and second openings 41, 42 pass completely through the retaining wrap 35 to expose a portion of the combustible heat source 4 which the first and second openings 41, 42 overlay. The first and second openings 41, 42 overlay at least about 30 percent of the longitudinal outer surface of the combustible heat source 4. The first and second openings 41, 42 are both the same size and are substantially rectangular. The first and second openings 41, 42 are evenly spaced about the combustible heat source 4. The first and second openings 41, 42 are defined on all sides by the retaining wrap 35, this results in a ring of retaining wrap 35 at the upstream end of the combustible heat source 4. The upstream edge of the first and second openings 41, 42 are disposed about 1 millimetre from the upstream end of the combustible heat source 4 such that the ring of retaining wrap 35 at the upstream end of the combustible heat source 4 is about 1 millimetre long.
[0190] The retaining wrap 35 further comprises a downstream portion 33 which circumscribes a portion of the aerosol-forming substrate 10. In the aerosol generating article 2 shown, the retaining wrap 35 circumscribes only a portion of the aerosol-forming substrate 10, extending from the upstream end of the aerosol-forming substrate 10 towards the downstream end of the aerosol-forming substrate 10. However, it will be appreciated that the retaining wrap 35 may circumscribe a larger or smaller amount of the aerosol-forming substrate 10. For example, the retaining wrap 35 may circumscribe the entire longitudinal surface of the aerosol-forming substrate 10.
[0191] The retaining wrap 35 comprises a layer of aluminium foil 36 disposed nearest to the combustible heat source 4 and the aerosol-forming substrate 10. The layer of aluminium foil 36 has a thickness of about 20 micrometres. The layer of aluminium foil 36 acts as a heat-conducting element. The retaining wrap 35 further comprises a layer of paper co-laminated with a metal 37. The layer of paper co-laminated with a metal 37 has a thickness of about 50 micrometres. The layer of aluminium foil 36 is attached to the layer of paper co-laminated with a metal 37. The retaining wrap 35 is adhered to the combustible heat source 4 using a silicate glue.
[0192] The components of the aerosol generating article 2 are held together by an outer wrapper 20. The outer wrapper 20 extends over a portion of the combustible heat source 4, although it will be appreciated that in other aerosol generating articles 2, the outer wrapper 20 does not extend over the combustible heat source 4.
[0193] The aerosol generating article 2 comprises one or more air inlets 40 around the periphery of the aerosol-forming substrate 10.
[0194] As shown in FIG. 1, a circumferential arrangement of air inlets 40 is provided in the plug wrap 26 of the aerosol-forming substrate 10, the retaining wrap 35, and the outer wrapper 20 to admit cool air (shown by dotted arrows in FIG. 1) into the aerosol-forming substrate 10.
[0195] The multi-segment component 50 may further comprise a removable cap (not shown) at its distal end and directly adjacent to the heat source 4. 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 one or both of the outer wrapper 20 and the wrapper 38 and connected to the rest of that wrapper along a line of weakness comprising a plurality of perforations in the wrapper. In such examples, to use the aerosol generating article, the user removes the removable cap 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 to locally break the wrapper by which the cap is connected. 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 heat source is partially exposed which enables the user to light the aerosol generating article.
[0196] In use, a user ignites the blind combustible heat source 4 of the aerosol generating article 2 according to the first embodiment of the invention and then draws on the mouthpiece 18. When a user draws on the mouthpiece 18, air (shown by dotted arrows in FIGS. 1) is drawn into the aerosol-forming substrate 10 of the aerosol generating article 2 through the air inlets 40.
[0197] The front portion of the aerosol-forming substrate 10 is heated by conduction through the rear face 8 of the blind combustible heat source 4 and the barrier 22.
[0198] FIG. 2 is a perspective view of the upstream end of the aerosol generating article shown in FIG. 1. In FIG. 2, the front face 6 of the combustible heat source 4 is clearly exposed. The first and second openings 41, 42 in the retaining wrap 35 are clearly visible, as is the ring of retaining wrap 35 at the upstream end of the combustible heat source. The circumferential arrangement of air inlets 40 is also shown.
[0199] FIG. 3 is a perspective view of the upstream end of a further aerosol generating article. It will be appreciated that the aerosol generating article 2 of FIG. 3 includes all of the features described in relation to the aerosol generating article 2 of FIGS. 1 and 2, and differs only in the arrangement of the retaining wrap 35.
[0200] The aerosol generating article 2 of FIG. 3 includes a retaining wrap 35. The retaining wrap 35 comprises an upstream portion which extends the full length of the combustible heat source 4 on the longitudinal outer surface of the combustible heat source 4. The upstream portion of the retaining wrap 35 comprises at least a first 51, a second 52, and a third 53 opening. It will be appreciated that the retaining wrap 35 shown in FIG. 3 may include further openings, but that these may not be visible in the perspective view of FIG. 3.
[0201] The openings 51, 52, 53 extend to the upstream end of the retaining wrap 35. The openings 51, 52, 53 therefore extend to the upstream end of the combustible heat source 4. Accordingly, the upstream ends of the openings 51, 52, 53 are defined by the upstream edge of the retaining wrap 35. The openings 51, 52, 53 are therefore not fully enclosed by the retaining wrap 35 as is the case in FIG. 2. The retaining wrap 35 therefore comprises a plurality of fingers which extend towards to the upstream end of the combustible heat source 4.
[0202] FIG. 4 is a perspective view of the upstream end of a further aerosol generating article. It will be appreciated that the aerosol generating article 2 of FIG. 3 includes all of the features described in relation to the aerosol generating article 2 of FIG. 3, and differs only in the arrangement of the retaining wrap 35.
[0203] Unlike in FIG. 3, the aerosol generating article 2 of FIG. 4 includes a retaining wrap which does not extend to the upstream end of the combustible heat source. In other words, the upstream end of the upstream portion of the retaining wrap is spaced apart from the upstream end of the combustible heat source.
[0204] FIGS. 5 to 9 show schematic plan views of the upstream end of aerosol generating articles according to the present invention. Each of the aerosol generating articles 2 include a retaining wrap 35 comprises an upstream portion which extends the full length of the combustible heat source 4 on the longitudinal outer surface of the combustible heat source 4. The upstream portion of the retaining wrap includes two openings 41, 51, only one of which is visible in each of FIGS. 5 to 9. The second opening, not shown, has the same size and shape as the openings 41, 51 shown and is disposed on the opposite side of the combustible heat source 4.
[0205] FIGS. 5 and 6 show aerosol generating articles 2 comprising a retaining wrap 35 which include openings 51 which extend all the way to the upstream end of the retaining wrap 35 as is the case in FIG. 3.
[0206] The opening 51 shown in FIG. 5 includes a narrow portion at the upstream end of the opening 51. The wider portion of the opening 51 shown in FIG. 4 has a length of 4.5 millimetres (shown by reference numeral 60), and a width of 10 millimetres (shown by reference numeral 61). The narrow portion of the opening 51 has a length of 1.5 millimetres (shown by reference numeral 62), and width of 2 millimetres (shown by reference numeral 63).
[0207] The opening 51 shown in FIG. 6 includes a narrow portion at the downstream end of the opening 51. The wider portion of the opening 51 shown in FIG. 6 has a length of 4.5 millimetres (shown by reference numeral 60), and a width of 10 millimetres (shown by reference numeral 61). The narrow portion of the opening 51 has a length of 1.5 millimetres (shown by reference numeral 62), and width of 2 millimetres (shown by reference numeral 63). The area of each of the openings 51 shown in both FIGS. 5 and 6 is 48 millimetres squared. Since each aerosol generating article 2 includes two identical openings 51, the total area of the combustible heat source 4 overlaid by the openings 51 in FIGS. 5 and 6 is 96 millimetres squared. In the aerosol generating articles 2 of FIGS. 5 and 6, the openings 51 in the retaining wrap overlay about 65 percent of the of the longitudinal outer surface of the combustible heat source 4.
[0208] FIGS. 7, 8, and 9 show aerosol generating articles 2 comprising a retaining wrap 35 which include openings 41 which do not extend all the way to the upstream end of the retaining wrap 35, but which are fully defined by the retaining wrap 35 to form a complete ring of retaining wrap 35 at the upstream end of the combustible heat source 4.
[0209] The openings 41 shown in both FIGS. 7 and 8 have a length of 4.5 millimetres (shown by reference numeral 70), and a width of 10 millimetres (shown by reference numeral 71).
[0210] The area of each of the openings 41 shown in both FIGS. 7 and 8 is 45 millimetres squared. Since each aerosol generating article 2 includes two identical openings 41, the total area of the combustible heat source 4 overlaid by the openings 41 in FIGS. 7 and 8 is 90 millimetres squared. In the aerosol generating articles 2 of FIGS. 7 and 8, the openings 41 in the retaining wrap overlay about 61 percent of the of the longitudinal outer surface of the combustible heat source 4.
[0211] The upstream end of the opening 41 of FIG. 7 is disposed 1.5 millimetres from the upstream end of the combustible heat source 4 (shown by reference numeral 72).
[0212] The upstream end of the opening 41 of FIG. 8 is disposed 2.5 millimetres from the upstream end of the combustible heat source 4 (shown by reference numeral 74).
[0213] The opening 41 shown in FIG. 9 has a length of 5.5 millimetres (shown by reference numeral 75), and a width of 10 millimetres (shown by reference numeral 71).
[0214] The area of the opening 41 shown in FIG. 9 is 55 millimetres squared. Since each aerosol generating article 2 includes two identical openings 41, the total area of the combustible heat source 4 overlaid by the openings 41 in FIG. 9 is 110 millimetres squared.
[0215] In the aerosol generating article 2 of FIG. 9, the openings 41 in the retaining wrap overlay about 65.8 percent of the of the longitudinal outer surface of the combustible heat source 4.
[0216] The upstream end of the opening 41 of FIG. 9 is disposed 1.5 millimetres from the upstream end of the combustible heat source 4 (shown by reference numeral 72).
[0217] The aerosol generating articles 2 shown in FIGS. 5, 6, and 7 include openings 41, the downstream ends of which are disposed about 3 millimetres upstream of the downstream end of the combustible heat source.
[0218] The aerosol generating articles 2 shown in FIGS. 8 and 9 include openings 41, the downstream ends of which are disposed about 2 millimetres upstream of the downstream end of the combustible heat source.
[0219] FIGS. 10 to 12 show temperature profiles of aerosol generating articles shown in each of FIGS. 5 to 9, taken at different points in the aerosol generating article.
[0220] The smoking articles shown in FIGS. 5 to 9 were manufactured according to the method of the present invention. Each smoking article was held at about 22 degrees Celsius, at about 45 percent relative humidity for 24 hours. The downstream ends of each smoking article were connected to a smoking machine, the combustible heat sources were ignited and each of the aerosol generating articles was subjected to the same puff cycle. The temperature of tobacco plug was measured using a thermocouple throughout the puff cycle to produce temperature profiles showing the temperature of the tobacco plug as a function of time. In the temperature profiles shown in FIGS. 10 to 12, the temperature is shown on the vertical axis 110 and is in degrees Celsius, and time is shown on the horizontal axis and is in seconds.
[0221] In the temperature profiles shown in FIGS. 10 to 12, line 101 is the temperature profile for the aerosol generating article shown in FIG. 5, line 103 is the temperature profile for the aerosol generating article shown in FIG. 6, line 104 is the temperature profile for the aerosol generating article shown in FIG. 7, line 104 is the temperature profile for the aerosol generating article shown in FIG. 8, and line 105 is the temperature profile for the aerosol generating article shown in FIG. 9.
[0222] A reference aerosol generating article was also tested under the same conditions. The reference aerosol generating article included the same features as those shown in FIGS. 5 to 9. However, the reference aerosol generating article did not include a retaining wrap having an upstream portion extending at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source and so was not according to the present invention. As a result, the combustible heat source of the reference aerosol generating article is considerably more exposed than the combustible heat sources of the aerosol generating articles shown in FIGS. 5 to 9. In the temperature profiles shown in FIGS. 10 and 11, line 106 is the temperature profile for the reference aerosol generating article.
[0223] FIG. 10 shows temperature profiles measured by a thermocouple in the aerosol generating substrate located about 2 millimetres downstream from the upstream end of the aerosol-forming substrate.
[0224] FIG. 11 shows the temperature profiles measured by a thermocouple in the aerosol generating substrate located about 1 millimetre downstream from the upstream end of the aerosol-forming substrate.
[0225] FIG. 12 shows the temperature profiles measured by a thermocouple in the aerosol generating substrate located about 7 millimetres downstream from the upstream end of the aerosol-forming substrate.
[0226] As can be seen from the temperature profiles shown in FIGS. 10 to 12, the temperature profiles of the aerosol generating articles shown in FIGS. 5 to 9 are similar to the temperature profiles for the reference aerosol generating article. Moreover, in all of FIGS. 10 to 12, the aerosol-forming substrates of the aerosol generating articles shown in FIGS. 5 to 9 are actually at a higher temperature than the aerosol-forming substrate of the reference aerosol generating article at least until about 200 seconds into the puff cycle. The maintenance of a high temperature in the aerosol-forming substrate is associated with improved generation of aerosol. The maintenance of a high temperature at the later time periods in the graph is associated with improved duration of aerosol generation from the aerosol generating substrate. Therefore, surprisingly it was found that the provision of a retaining wrap having an upstream portion extending at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source did not have a substantial negative effect of the performance of the combustible heat source such that the combustible heat source rendered non-functional the aerosol generating article.
[0227] Additionally, FIG. 12 shows that even at the far downstream end of the aerosol-forming substrate, at 7 millimetres from the upstream end of the aerosol-forming substrate, the aerosol generating articles of the present invention maintain similar temperatures to those of the reference aerosol generating article 106. This is particularly advantageous since it demonstrates that the aerosol-forming substrates of the present invention are being heated along their full length allowing aerosol to be generated over a high proportion of the aerosol-forming substrate.
[0228] Furthermore, it was concluded that of the aerosol generating articles shown in FIGS. 5 to 9, the aerosol generating article shown in FIG. 5, with the temperature profile shown by line 101, performed best. As can be seen from FIGS. 10 to 12, the aerosol forming substrate of the aerosol generating article shown in FIG. 5 was able to maintain the highest temperature for the longest time. In particular, both FIGS. 10 to 12 show that the temperature of the aerosol-forming substrate of the aerosol generating article shown in FIG. 5 is surprisingly higher at the end of the puff cycle than the temperatures the aerosol-forming substrates of the other aerosol generating articles according to the present invention.
[0229] There is also provided a method for manufacturing an aerosol generating article. The method comprises providing a length of paper. The paper is a paper co-laminated with a metal. In some embodiments, a patch of aluminium foil is then added to the paper. At least one opening is then cut through the aluminium patch and the paper to form a retaining wrap. The at least one opening is forms using a stamping process. The material (paper and aluminium foil) defined by the cut line is removed to form the opening. The retaining wrap is then applied to a combustible heat source and an aerosol-forming substrate such that an upstream portion of the retaining wrap extends at least about 50 percent of the way along the length of the combustible heat source on the longitudinal outer surface of the combustible heat source, the at least one opening being in the upstream portion of the retaining wrap, and a downstream portion of the retaining wrap circumscribes at least a portion of the aerosol-forming substrate.
[0230] 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.
