AEROSOL GENERATING ARTICLE INCLUDING A HEAT-CONDUCTING ELEMENT AND A SURFACE TREATMENT

Abstract

There is provided an aerosol-generating article including a combustible heat source; an aerosol-forming substrate disposed in thermal communication with the combustible heat source; and a heat-conducting component disposed around at least a portion of the aerosol-forming substrate, the heat-conducting component including an outer surface forming at least part of an outer surface of the aerosol-generating article, wherein at least a portion of the outer surface of the heat-conducting component includes a surface coating and has an emissivity of less than about 0.6. A method of manufacturing the aerosol-generating article is also provided.

Claims

1.-15. (canceled)

16. An aerosol-generating article, comprising: a combustible heat source; an aerosol-forming substrate disposed in thermal communication with the combustible heat source; and a heat-conducting component disposed around at least a portion of the aerosol-forming substrate, the heat-conducting component comprising an outer surface forming at least part of an outer surface of the aerosol-generating article, wherein at least a portion of the outer surface of the heat-conducting component comprises a surface coating and has an emissivity of less than about 0.6.

17. The aerosol-generating article according to claim 16, wherein the emissivity of the outer surface of the heat-conducting component is less than about 0.5.

18. The aerosol-generating article according to claim 16, wherein the emissivity of the outer surface of the heat-conducting component is greater than about 0.1.

19. The aerosol-generating article according to claim 16, wherein the surface coating comprises a filler material comprising one or more materials selected from graphite, metal oxides, and metal carbonates.

20. The aerosol-generating article according to claim 16, wherein the surface coating is discontinuous.

21. The aerosol-generating article according to claim 16, wherein the heat conducting component further comprises a first heat-conducting element disposed around and in contact with a downstream portion of the combustible heat source and an adjacent upstream portion of the aerosol-forming substrate, and a second heat-conducting element disposed around at least a portion of the first heat-conducting element and comprising an outer surface forming at least part of the outer surface of the aerosol-generating article.

22. The aerosol-generating article according to claim 21, wherein the second heat-conducting element is radially separated from the first heat-conducting element by at least one layer of a heat-insulating material extending around at least a portion of the first heat-conducting element between the first and second heat-conducting elements.

23. The aerosol-generating article according to claim 16, wherein at least a portion of the outer surface of the heat-conducting component comprises a surface treatment, and wherein the surface treatment comprises at least one of embossing, debossing, and combinations thereof.

24. The aerosol-generating article according to claim 16, wherein the surface coating comprises at least one pigment.

25. The aerosol-generating article according to claim 16, wherein the surface coating comprises a translucent material.

26. The aerosol-generating article according to claim 16, wherein the surface coating comprises at least one of metal particles, metal flakes, or both the metal particles and the metal flakes.

27. The aerosol-generating article according to claim 16, wherein the heat-conducting component comprises a metal foil.

28. A method of manufacturing an aerosol-generating article comprising a combustible heat source, an aerosol-forming substrate disposed in thermal communication with the combustible heat source, and a heat-conducting component disposed around at least a portion of the aerosol-forming substrate, the heat-conducting component comprising an outer surface forming at least part of an outer surface of the aerosol-generating article, the method comprising applying a coating composition to at least a portion of the outer surface of the heat-conducting component such that a coated portion of the heat-conducting component has an emissivity of less than about 0.6.

29. The method according to claim 28, wherein the coating composition includes a filler material, a binder, and a solvent.

30. The method according to claim 29, wherein the filler material comprises one or more materials selected from graphite, metal oxides, and metal carbonates.

Description

EMBODIMENTS AND EXAMPLES

[0140] The invention will now be further described, by way of example only, with reference to the accompanying Figures in which:

[0141] FIG. 1 shows a cross-sectional view of an aerosol generating article in accordance with the present invention;

[0142] FIG. 2 shows a test apparatus for determining the effect of different second heat-conducting elements on thermal loss from an aerosol generating article;

[0143] FIG. 3 shows a graph of outer surface temperature against time for different second heat-conducting element materials when tested on the apparatus of FIG. 2;

[0144] FIG. 4 shows a graph of internal temperature against time for different second heat-conducting element materials when tested on the apparatus of FIG. 2;

[0145] FIG. 5 shows a graph of internal temperature against time for second heat-conducting elements when tested on the apparatus of FIG. 2 to show the effect of different embossing patterns;

[0146] FIG. 6 shows a graph of internal temperature against time for second heat-conducting elements when tested on the apparatus of FIG. 2 to show the effect of different surface coatings;

[0147] FIG. 7 shows a summary of the measured emissivity values for the different embossing patterns and the different surface coatings used in the tests of FIGS. 5 and 6;

[0148] FIGS. 8 and 9 show test data for aerosol generating articles comprising second heat-conducting elements having the different surface coatings of FIG. 6 and smoked according to the Health Canada Intense smoking regime; and

[0149] FIGS. 10 and 11 show comparative test data for aerosol generating articles comprising second heat-conducting elements having a surface coating of calcium carbonate and smoked according to the Health Canada Intense smoking regime.

[0150] The aerosol generating article 2 shown in FIG. 1 comprises a combustible carbonaceous heat source 4, an aerosol-forming substrate 6, an airflow directing element 44, an elongate expansion chamber 8 and a mouthpiece 10 in abutting coaxial alignment. The combustible carbonaceous heat source 4, aerosol-forming substrate 6, airflow directing element 44, elongate expansion chamber 8 and mouthpiece 10 are overwrapped in an outer wrapper of cigarette paper 12 of low air permeability.

[0151] As shown in FIG. 1, a non-combustible, gas-resistant, first barrier coating 14 is provided on substantially the entire rear face of the combustible carbonaceous heat source 4. In an alternative embodiment, a non-combustible, substantially air impermeable first barrier is provided in the form of a disc that abuts the rear face of the combustible carbonaceous heat source 4 and the front face of the aerosol-forming substrate 6.

[0152] The combustible carbonaceous heat source 4 is a blind heat source so that air drawn through the aerosol generating article for inhalation by a user does not pass through any airflow channels along the combustible heat source 4.

[0153] The aerosol-forming substrate 6 is located immediately downstream of the combustible carbonaceous heat source 4 and comprises a cylindrical plug of tobacco material 18 comprising glycerine as an aerosol former and circumscribed by a filter plug wrap 20.

[0154] A heat-conducting component comprises a first heat-conducting element 22 consisting of a tube of aluminium foil surrounds and is in contact with a downstream portion 4b of the combustible carbonaceous heat source 4 and an abutting upstream portion 6a of the aerosol-forming substrate 6. As shown in FIG. 1, a downstream portion of the aerosol-forming substrate 6 is not surrounded by the first heat-conducting element 22.

[0155] An airflow directing element 44 is located downstream of the aerosol-forming substrate 6 and comprises an open-ended, substantially air impermeable hollow tube 56 made of, for example, cardboard, which is of reduced diameter compared to the aerosol-forming substrate 6. The upstream end of the open-ended hollow tube 56 abuts the aerosol-forming substrate 6. The downstream end of the open-ended hollow tube 56 is surrounded by an annular substantially air impermeable seal 58 of substantially the same diameter as the aerosol-forming substrate 6. The remainder of the open-ended hollow tube is embedded in a cylindrical plug of cellulose acetate tow 60 of substantially the same diameter as the aerosol-forming substrate 6.

[0156] The open-ended hollow tube 56 and cylindrical plug of cellulose acetate tow 60 are circumscribed by an air permeable inner wrapper 50. A circumferential row of air inlets 52 are provided in the outer wrapper 12 and the inner wrapper 50.

[0157] The elongate expansion chamber 8 is located downstream of the airflow directing element 44 and comprises a cylindrical open-ended tube of cardboard 24. The mouthpiece 10 of the aerosol generating article 2 is located downstream of the expansion chamber 8 and comprises a cylindrical plug of cellulose acetate tow 26 of very low filtration efficiency circumscribed by filter plug wrap 28. The mouthpiece 10 may be circumscribed by tipping paper (not shown).

[0158] The heat-conducting component further comprises a second heat-conducting element 30 consisting of a tube of aluminium foil surrounds and is in contact with the outer wrapper 12. The second heat-conducting element 30 is positioned over the first heat-conducting element 22 and is of the same dimensions as the first heat-conducting element 22. The second heat-conducting element 30 therefore directly overlies the first heat-conducting element 22, with the outer wrapper 12 between them. The outer surface of the second heat-conducting element 30 is coated with a surface coating, such as a glossy coloured coating, which yields an emissivity value of less than about 0.6, preferably less than about 0.2, for the outer surface of the second heat-conducting element 22.

[0159] In use, the user ignites the combustible carbonaceous heat source 4, which heats the aerosol-forming substrate 6 by conduction. The user then draws on the mouthpiece 10 so that cool air is drawn into the aerosol generating article 2 through the air inlets 52. The drawn air passes upstream between the exterior of the open-ended hollow tube 56 and the inner wrapper 50 through the cylindrical plug of cellulose acetate tow 60 to the aerosol-forming substrate 6. The heating of the aerosol-forming substrate 6 releases volatile and semi-volatile compounds and glycerine from the tobacco material 18, which are entrained in the drawn air as it reaches the aerosol-forming substrate 6. The drawn air is also heated as it passes through the heated aerosol-forming substrate 6. The heated drawn air and entrained compounds then pass downstream through the interior of the hollow tube 56 of the airflow directing element 44 to the expansion chamber 8, where they cool and condense. The cooled aerosol then passes downstream through the mouthpiece 10 of the aerosol generating article 2 into the mouth of the user.

[0160] The non-combustible, substantially air impermeable, barrier coating 14 provided on the entire rear face of the combustible carbonaceous heat source 4 isolates the combustible carbonaceous heat source 4 from the airflow pathways through the aerosol generating article 2 such that, in use, air drawn through the aerosol generating article 2 along the airflow pathways does not directly contact the combustible carbonaceous heat source 4.

[0161] The second heat-conducting element 30 retains heat within the aerosol generating article 2 to help maintain the temperature of the first heat-conducting element 22 during smoking. This in turn helps maintain the temperature of the aerosol-forming substrate 6 to facilitate continued and enhanced aerosol delivery.

[0162] FIG. 2 shows a test apparatus 100 for simulating the heating of an aerosol generating article in accordance with the present invention, which is used for testing the performance of different second heat-conducting elements, including those having different surface treatments. The test apparatus 100 comprises a cylindrical aluminium body 102 around which a test material 104 is wrapped. The test material 104 simulates a second heat-conducting element in an aerosol generating article according to the invention.

[0163] During the test, a coil heater 106 embedded within the aluminium body 102 simulates the heating effect of a combustible heat source at the upstream end of an aerosol generating article. To enable measurement of the emissivity of the outer surface of the test material 104 in accordance with ISO 18434-1, the voltage across the coil heater 106 is increased in stages to provide periods of stabilised elevated temperature during the heating process. Specifically, the voltage across the coil heater 106 is increased incrementally to 6 volts, 11 volts, 14 volts, 17 volts, 19.5 volts, 21 volts, and 24 volts, with a delay of 10 minutes between each voltage increase to allow the temperature of the test material 104 to stabilise.

[0164] During the test procedure, first and second thermocouples 108 and 110 record the temperature at the outer surface of the test material 104 and the interior of the aluminium body 102 respectively. Each thermocouple 108, 110 is positioned 7 millimetres from the upstream end 112 of the aluminium body 102.

[0165] FIG. 3 shows a graph of surface temperature, measured using thermocouple 108, against time for different second heat-conducting element materials when tested on the apparatus of FIG. 2. The materials tested for the second heat-conducting element were: aluminium only; paper only; a paper-aluminium co-laminate with the aluminium layer forming the outer surface; and a paper-aluminium co-laminate with the paper layer forming the outer surface. The aluminium had a measured emissivity of 0.09 and the paper had a measured emissivity of 0.95. It is shown in FIG. 3 that the lower emissivity of the aluminium layer compared to the paper layer resulted in a higher outer surface temperature of the second heat-conducting element due to reduced radiative heat loss.

[0166] As shown in FIG. 4, which shows a graph of interior temperature against time, measured using thermocouple 110 during the same test as FIG. 3, the reduced radiative heat loss achieved by using a second heat-conducting element having a low emissivity at the outer surface also results in an increased internal temperature within the simulated aerosol generating article. Based on this data, the present inventors have recognised that utilising a second heat-conducting element having a low emissivity at its outer surface provides a more thermally efficient aerosol generating article and therefore a desirable increase in the internal temperature during smoking.

[0167] The heating test was repeated using three different paper-aluminium co-laminates each having a different embossment pattern, and in each case with the aluminium layer forming the outer surface of the second heat-conducting element. The test data is shown in FIG. 5, which shows the internal temperature measured with thermocouple 110 against time for all three test materials, as well as the data for the non-embossed co-laminate (for both aluminium and paper forming the outer surface) for reference. It is shown in the data in FIG. 5 that embossing the material forming the second heat conducting element has substantially no effect on the internal temperature of the simulated aerosol generating article during the heating test, which can be attributed to the embossing having substantially no effect on the emissivity at the outer surface of the second heat-conducting element. This is shown in the data in FIG. 7, which shows that the measured values of emissivity for the three embossing patterns were 0.092, 0.085 and 0.092, which are substantially the same as the emissivity value of 0.09 for the non-embossed co-laminate with the aluminium layer forming the outer surface.

[0168] The heating test was repeated again using six different paper-aluminium co-laminates each having a different surface coating of coloured ink applied over the outer surface of the aluminium layer, and in each case with the aluminium layer forming the outer surface of the second heat-conducting element. The six different surface coatings tested were: glossy gold colour; matt pink colour; glossy pink colour; matt green colour; glossy orange colour; and matt black colour. The test data is shown in FIG. 6, which shows the internal temperature measured with thermocouple 110 against time for all six test materials, as well as the data for the non-coated co-laminate (for both aluminium and paper forming the outer surface) for reference. It is shown in FIG. 6 that coating the aluminium layer in a matt black ink resulted in an internal temperature during the test that was similar to that obtained with the paper layer of the co-laminate forming the outer surface of the second heat-conducting element. The other inks had no significant effect on the internal temperature of the simulated aerosol generating article when compared with the data for the uncoated aluminium layer forming the outer surface of the second heat-conducting element. Therefore, based on this data, the present inventors have recognised that applying a surface coating to the material forming the outer surface of the second heat-conducting element may have a significant effect on the thermal performance of the second heat-conducting element, depending on the particular surface coating used.

[0169] In this regard, the emissivity of the different test materials used for the test in FIG. 6 was measured and the data is presented in FIG. 7. It is shown in FIG. 7 that, although applying a coloured coating to the aluminium layer increases the emissivity compared to the uncoated aluminium layer, the effect was most significant when the coating was a matt black colour. Accordingly, there is a direct correlation between the increase in the emissivity value as a result of applying a coloured coating and the resulting decrease in internal temperature of the simulated aerosol generating article during the heating test. Accordingly, the present inventors have recognised that, when applying a surface coating to the outer surface of the second heat-conducting element, the surface coating should be selected to maintain or provide a low emissivity value to prevent an undesirable reduction, or yield a desirable increase, in the internal temperature of the aerosol generating article during smoking.

[0170] Aerosol generating articles were constructed using the six coated co-laminates used for the tests in FIGS. 6 and 7, with the coated aluminium layer forming the outer surface of the second heat-conducting element in each case. For reference, an aerosol generating article was also constructed using a paper-aluminium co-laminate with an uncoated matt aluminium layer forming the outer surface of the second heat conducting element. In each case the co-laminate comprised a paper layer having a thickness of 73 micrometres and a basis weight of 45 grams per square metre laminated to an aluminium foil having a thickness of 6.3 micrometres. The aerosol generating articles were then smoked according to the Health Canada Intense smoking regime (55 cubic centimetres puff volume, 30 second puff frequency, 2 second puff duration) and the resulting data for delivery of glycerine, nicotine and total particulate matter (TPM) is shown in FIGS. 8 and 9.

[0171] FIGS. 8 and 9 show that the matt pink, matt green, glossy pink and glossy orange coatings resulted in similar glycerine, nicotine and TPM delivery compared to the reference uncoated matt aluminium article. The glossy gold coating resulted in reduced but acceptable delivery compared to the reference article. The matt black coating resulted in a significantly reduced and unacceptable delivery compared to the reference article. Based on the data in FIGS. 8 and 9 combined with the measured emissivity values in FIG. 7, the present inventors have recognised that when providing a surface treatment on the outer surface of a material forming a second heat-conducting element the surface treatment should be selected to maintain or provide an emissivity of less than about 0.6.

[0172] In a further example, aerosol-generating articles were constructed to examine the effect of a calcium carbonate coating on an outer surface of a second heat-conducting element. Sets of first and second reference articles were constructed, each having an uncoated second heat-conducting element, and then smoked according to the Health Canada Intense smoking regime (55 cubic centimetres puff volume, 30 second puff frequency, 2 second puff duration). The temperature profiles during smoking for the first and second reference articles are shown in FIGS. 10 and 11 (FIG. 10 shows temperature measured at the downstream end of the heat source, and FIG. 11 shows temperature measured at the upstream end of the aerosol-forming substrate). The second reference articles each include a heat source that provides a greater thermal output than the heat source of each of the first reference articles. As a result, the second reference articles exhibit a generally hotter temperature profile than the first reference articles.

[0173] For comparison, a set of third articles was constructed, each identical to the second reference articles except for the addition of a lacquer coating to the outer surface of the second heat-conducting elements, the lacquer comprising 60 percent calcium carbonate. The set of third articles was then smoked according to the same smoking regime and the results are shown in FIGS. 10 and 11. As shown in FIGS. 10 and 11, applying a calcium carbonate coating to the outer surface of the second heat-conducting elements of second reference articles modifies the temperature profiles of the second reference articles during smoking so that they approximate the temperature profiles of the first reference articles during smoking, despite the greater thermal output of the heat source in each second reference article compared to the thermal output of the heat source in each first reference article.

[0174] The embodiments and examples shown in FIGS. 1 to 11 and described herein illustrate but do not limit the invention. Other embodiments of the invention may be made without departing from the scope thereof, and it is to be understood that the specific embodiments described herein are not limiting.