Aerosol-generating article comprising a flame retardant wrapper

Abstract

The present invention relates to an aerosol-generating article comprising an aerosol-generating substrate and adapted to produce an inhalable aerosol upon heating.SOLUTION: An aerosol-generating article (10,110) for generating an inhalable aerosol upon heating is provided. The aerosol-generating article (10,110) comprises a rod (12) of aerosol-generating substrate extending from a proximal rod end to a distal rod end upstream of the proximal rod end, a downstream section (14) at a position downstream of the rod (12) of aerosol-generating substrate, and a wrapper (70) circumscribing at least the rod (12) of aerosol-generating substrate, the wrapper (70) comprising a wrapping substrate having a basis weight. At least a treated portion (72) of the wrapper (70) extending between the proximal rod end and the distal rod end comprises a flame retardant composition comprising one or more flame retardant compounds. Thus, the treated portion (72) of the wrapper (70) has an overall basis weight that is greater than the basis weight of the wrapping substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aerosol-generating article that includes an aerosol-generating substrate and is adapted to generate an inhalable aerosol upon heating. [Background technology]

[0002] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than combusted are known in the art.

[0003] In a traditional cigarette, the consumer lights a flame at the distal end of the cigarette while drawing air through the proximal end. Heat generated locally by the flame and oxygen in the air drawn through the cigarette ignites the distal end of the cigarette, and combustion of the tobacco rod and surrounding wrapper generates inhalable smoke. In contrast, in a heated aerosol-generating article, the aerosol is generated by the more gentle transfer of heat from a heat source to a physically separated aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] Numerous prior art documents disclose aerosol generating devices for consuming aerosol-generating articles. These devices include, for example, electrically heated aerosol generating devices in which an aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generating device to an aerosol-generating substrate of the heated aerosol-generating article. For example, electrically heated aerosol generating devices have been proposed that include an internal heater blade adapted to be inserted into the aerosol-generating substrate. Alternatively, inductively heated aerosol-generating articles have also been proposed that include an aerosol-generating substrate and a susceptor disposed within the aerosol-generating substrate.

[0005] Aerosol-generating articles in which a tobacco-containing substrate is heated rather than combusted present several challenges not encountered with conventional smoking articles. The tobacco-containing substrate is typically heated to a significantly lower temperature compared to the temperature reached by the combustion front of a conventional cigarette. However, the heating temperature should not be too low, which can affect nicotine release from the tobacco-containing substrate and nicotine delivery to the consumer. Furthermore, to maximize heat transfer efficiency, it is generally desirable for the heat source to be positioned as close as possible to the aerosol-generating substrate, preferably in contact with it.

[0006] Thus, in existing aerosol-generating articles designed to be heated by a heater blade inserted into the aerosol-generating substrate or by a susceptor disposed within the aerosol-generating substrate, the aerosol-generating substrate is typically surrounded by a wrapper that combines a metal foil, such as aluminum foil, with a paper layer. Thus, the metal layer sandwiched between the aerosol-generating substrate and the paper wrapper acts as a heat shield, preventing the paper wrapper from scorching or carbonizing during use.

[0007] This is desirable because it enhances the safety of the aerosol-generating article and prevents the delivery of paper combustion or pyrolysis products to the consumer during use. However, the inclusion of one such metal shield makes the manufacturing process more complex and expensive and can increase the environmental impact of the aerosol-generating article when it is disposed of after use. Furthermore, because the original visual impact of the aerosol-generating article is substantially maintained during use, it can be difficult to determine whether the aerosol-generating article is being used effectively.

[0008] It is therefore desirable to provide new and improved aerosol-generating articles that are easier to dispose of and have a reduced impact on the environment, while at the same time being adapted to prevent scorching or charring of the article during use. Secondly, there is a generally felt need for new and improved aerosol-generating articles that substantially prevent misuse of the article, such that the article can only be properly used in an aerosol-generating device adapted to heat an aerosol-generating substrate, and not used as a conventional cigarette. Furthermore, it is also desirable to provide one such aerosol-generating article that can be manufactured efficiently and rapidly, preferably without requiring extensive modification of existing equipment.

[0009] It would therefore be desirable to provide new and improved aerosol-generating articles adapted to achieve at least one of the above-mentioned desirable results. Summary of the Invention

[0010] The present disclosure relates to an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article comprising a rod of aerosol-generating substrate extending from a proximal end of the rod to a distal end upstream of the proximal end of the rod. The aerosol-generating substrate may include at least one aerosol former. The aerosol-generating article may comprise a downstream section downstream of the rod of aerosol-generating substrate. The aerosol-generating article may comprise a wrapper surrounding at least the rod of aerosol-generating substrate. The wrapper may comprise a wrapping substrate having a basis weight. At least a treated portion of the wrapper extending between the proximal end and the distal end of the rod may comprise a flame-retardant composition including one or more flame-retardant compounds, such that the treated portion of the wrapper has a total basis weight greater than the basis weight of the wrapping substrate. The treated portion may extend over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrate.

[0011] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article comprising: a rod of aerosol-generating substrate extending from a proximal end of the rod to a distal end upstream of the proximal end of the rod; a downstream section located downstream of the rod of aerosol-generating substrate; and a wrapper surrounding at least the rod of aerosol-generating substrate, the wrapper comprising a wrapping substrate having a basis weight. At least a treated portion of the wrapper extending between the proximal end and the distal end of the rod comprises a flame-retardant composition including one or more flame-retardant compounds, such that the treated portion of the wrapper has a total basis weight greater than the basis weight of the wrapping substrate. The treated portion extends over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrate.

[0012] The present disclosure further relates to a method of manufacturing an aerosol-generating article for generating an inhalable aerosol upon heating. The method may include providing a continuous rod of aerosol-generating substrate. The method may include the further step of surrounding the continuous rod of aerosol-generating substrate with a wrapper, the wrapper comprising a wrapping substrate having a dry basis weight. In addition, the method may include treating at least a portion of the wrapper with a flame-retardant composition comprising one or more flame-retardant compounds, e.g., providing the treated portion of the wrapper with a total dry basis weight greater than the dry basis weight of the wrapping substrate. The method may further include cutting the treated and wrapped continuous rod of aerosol-generating substrate into individual rods, each individual rod extending from a proximal end of the individual rod to a distal end of the individual rod upstream of the proximal end of the individual rod, such that the treated portion of the individual rod extends over at least about 80% of the outer surface area of ​​the individual rod.

[0013] According to the present invention, there is further provided a method of manufacturing an aerosol-generating article for producing an inhalable aerosol upon heating, the method comprising: providing a continuous rod of aerosol-generating substrate; surrounding the continuous rod of aerosol-generating substrate with a wrapper, the wrapper comprising a wrapping substrate having a dry basis weight; treating at least a portion of the wrapper with a flame-retardant composition comprising one or more flame-retardant compounds to provide a treated portion of the wrapping having a total dry basis weight greater than the dry basis weight of the wrapping substrate; and cutting the treated, wrapped continuous rod of aerosol-generating substrate into individual rods, the individual rods extending from proximal ends of the individual rods to distal ends of the individual rods upstream of the proximal ends of the individual rods, such that the treated portions of the individual rods extend across at least about 80 percent of the outer surface area of ​​the individual rods.

[0014] The present disclosure also relates to an aerosol-generating system comprising an electrically operated aerosol-generating device and an aerosol-generating article as described above. The aerosol-generating device may include means for heating the rod of the aerosol-generating substrate to a temperature sufficient to generate an aerosol from the aerosol-generating substrate.

[0015] According to the present invention, there is further provided an aerosol generating system comprising the electrically operated aerosol generating device and an aerosol-generating article as described above, the aerosol generating device including means for heating the rod of the aerosol-generating substrate to a temperature sufficient to generate an aerosol from the aerosol-generating substrate.

[0016] As briefly described above, the present invention provides an aerosol-generating article for generating an inhalable aerosol upon heating, the article including a rod of aerosol-generating substrate extending from a proximal end of the rod to a distal end of the rod upstream of the proximal end of the rod, and a downstream section of the aerosol-generating substrate located downstream of the rod. More particularly, the present invention provides an aerosol-generating article for generating an inhalable aerosol upon heating at a temperature of from about 100° C. to about 800° C., preferably from about 150° C. to about 500° C., and more preferably from about 200° C. to about 300° C.

[0017] These temperatures are significantly lower than those reached by conventional cigarettes when a tobacco-containing substrate is burned, and are even significantly lower than the temperatures reached by commercially available cigarette lighters, which range from about 1000 degrees Celsius to 2000 degrees Celsius and even higher.

[0018] The aerosol-generating article further includes a wrapper surrounding at least the rod of aerosol-generating substrate, the wrapper comprising a wrapping substrate having a certain basis weight. In contrast to existing aerosol-generating articles, at least a treated portion of the wrapper extending between the rod proximal end and the rod distal end comprises a flame-retardant composition including one or more flame-retardant compounds. Thus, the treated portion of the wrapper has a total basis weight greater than the basis weight of the wrapping substrate. The treated portion extends over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrate.

[0019] The inventors have discovered that by surrounding an aerosol-generating substrate with a wrapper, the treated portion of the wrapper comprising a flame-retardant composition, and the treated portion extending over a majority of the outer surface area of ​​the rod of the aerosol-generating substrate, the wrapper and underlying aerosol-generating substrate can be advantageously prevented from scorching or burning during use. In other words, combustion and thermal decomposition of components of the aerosol-generating article according to the invention can be advantageously substantially prevented.

[0020] In the aerosol-generating article of the present invention, this is desirably achieved without the need for an additional layer of metal foil or other heat-shielding material to be included in the aerosol-generating article. This simplifies the manufacturing process and therefore reduces manufacturing costs. Furthermore, when a used aerosol-generating article is discarded, it is easier to dispose of the aerosol-generating article of the present invention because there is no need to separate and recover valuable recyclable materials, such as aluminum foil. Furthermore, the inventors discovered that by enclosing the aerosol-generating substrate in the wrapper described above, when the aerosol-generating substrate is exposed to temperatures ranging from about 100°C to about 800°C during use, the aerosol-generating article undergoes significant discoloration, with the surface of the wrapper turning dark brown or black. This allows consumers to immediately know whether the aerosol-generating article has been used and should be discarded.

[0021] By adjusting the amount of flame retardant compound in the wrapper (e.g., amount per square meter of surface area of ​​the treated portion), the extent to which the surface of the wrapper is treated with the flame retardant composition within the ranges described above, and the formulation of the flame retardant composition (i.e., the nature of the flame retardant compound), it is possible to advantageously improve the flame retardant properties of the wrapper and the aerosol-generating article as a whole.

[0022] Thus, the present invention provides an improved aerosol-generating article that can substantially prevent scorching and charring of the aerosol-generating substrate and wrapper during use because, by providing one or more flame-retardant compounds on or within the wrapper, or both, the heat supplied to the article to generate the aerosol can be substantially prevented from causing thermal decomposition or combustion of the wrapper substrate.

[0023] Aerosol-generating articles according to the present invention advantageously facilitate disposal and reduce environmental impact because the article does not need to include a metal foil layer, as is common with existing aerosol-generating articles.

[0024] Furthermore, aerosol-generating articles according to the present invention have the added benefit of only being able to be used correctly as intended, i.e., in combination with a device adapted to heat the aerosol-generating substrate. Indeed, unlike conventional cigarettes, aerosol-generating articles according to the present invention are essentially unable to light and sustain a burn like conventional cigarettes.

[0025] According to the present invention, an aerosol-generating article is provided for generating an inhalable aerosol upon heating.

[0026] The term "aerosol-generating article" is used herein to mean an article in which an aerosol-generating substrate is heated to generate an inhalable aerosol for delivery to a consumer. As used herein, the term "aerosol-generating substrate" means a substrate capable of generating an aerosol by releasing a volatile compound upon heating.

[0027] A conventional cigarette is lit when a user applies a flame to one end of the cigarette and draws air through the other end. Localized heat provided by the flame and oxygen in the air drawn through the cigarette ignites the end of the cigarette, and the resulting combustion produces inhalable smoke. In contrast, in heated aerosol-generating articles, the aerosol is generated by heating a flavor-generating substrate (such as tobacco). Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which the aerosol is generated by the transfer of heat from a combustible fuel element or heat source to a physically separated aerosol-forming material. For example, the aerosol-generating article according to the present invention finds particular application in aerosol-generating systems comprising an electrically heated aerosol generator having an internal heater blade adapted to be inserted into a rod of the aerosol-generating substrate. Aerosol-generating articles of this type are described in the prior art, for example, in EP 0 822 670.

[0028] As used herein, the term "aerosol-generating device" refers to a device that includes a heater element that interacts with an aerosol-generating substrate of an aerosol-generating article to generate an aerosol.

[0029] As used herein in connection with the present invention, the term "rod" is used to denote a generally cylindrical element of substantially circular, oval or elliptical cross section.

[0030] As used herein, the term "longitudinal" refers to a direction corresponding to a major longitudinal axis of the aerosol-generating article extending between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms "upstream" and "downstream" describe the relative positions of elements (or portions of elements) of the aerosol-generating article with respect to the direction in which aerosol is transported through the aerosol-generating article during use.

[0031] In use, air is drawn longitudinally through the aerosol-generating article. The term "transverse" refers to a direction perpendicular to the longitudinal axis. Any reference to a "cross section" of an aerosol-generating article or a component of an aerosol-generating article refers to a transverse cross section, unless otherwise specified.

[0032] The term "length" refers to the dimension of a component of an aerosol-generating article in the longitudinal direction. For example, it may be used to refer to the dimension of a rod or elongated tubular element in the longitudinal direction.

[0033] An aerosol-generating article according to the present invention comprises a rod of aerosol-generating substrate, the rod of aerosol-generating substrate extending from a proximal end of the rod to a distal end upstream of the proximal end of the rod, and a downstream section located downstream of the rod of aerosol-generating substrate.

[0034] In an aerosol-generating article according to the invention, at least the rod of aerosol-generating substrate is surrounded by a wrapper, which means that in an aerosol-generating article according to the invention, the same wrapper surrounding the rod of aerosol-generating substrate may also surround at least a part of the downstream section of the aerosol-generating article, or at least a part of any additional components, or both, provided in a position upstream of the rod of aerosol-generating substrate.

[0035] The aerosol-generating article may have a total length of from about 35 millimeters to about 100 millimeters.

[0036] Preferably, the overall length of an aerosol-generating article according to the present invention is at least about 38 millimeters. More preferably, the overall length of an aerosol-generating article according to the present invention is at least about 40 millimeters. Even more preferably, the overall length of an aerosol-generating article according to the present invention is at least about 42 millimeters.

[0037] In some embodiments, the overall length of an aerosol-generating article according to the present invention is preferably 80 millimeters or less. More preferably, the overall length of an aerosol-generating article according to the present invention is 70 millimeters or less. Even more preferably, the overall length of an aerosol-generating article according to the present invention is 60 millimeters or less. Most preferably, the overall length of an aerosol-generating article according to the present invention is 50 millimeters or less.

[0038] In preferred embodiments, the total length of the aerosol-generating article is between about 38 millimeters and about 70 millimeters, more preferably between about 40 millimeters and about 70 millimeters, and even more preferably between about 42 millimeters and about 70 millimeters. In other embodiments, the total length of the aerosol-generating article is between about 38 millimeters and about 60 millimeters, more preferably between about 40 millimeters and about 60 millimeters, and even more preferably between about 42 millimeters and about 60 millimeters. In further embodiments, the total length of the aerosol-generating article is between about 38 millimeters and about 50 millimeters, more preferably between about 40 millimeters and about 50 millimeters, and even more preferably between about 42 millimeters and about 50 millimeters. In an exemplary embodiment, the total length of the aerosol-generating article is about 45 millimeters.

[0039] In other embodiments, the overall length of the aerosol-generating article according to the present invention is preferably at least about 40 millimeters, more preferably about 50 millimeters, and even more preferably about 60 millimeters. In these embodiments, the overall length of the aerosol-generating article is preferably no more than about 95 millimeters, more preferably no more than about 90 millimeters, even more preferably no more than about 85 millimeters, and most preferably no more than about 80 millimeters.

[0040] In a preferred embodiment, the total length of the aerosol-generating article is from about 40 millimeters to about 95 millimeters, preferably from about 40 millimeters to about 90 millimeters, more preferably from about 40 millimeters to about 85 millimeters, and even more preferably from about 40 millimeters to about 80 millimeters. In another embodiment, the total length of the aerosol-generating article is from about 50 millimeters to about 95 millimeters, preferably from about 50 millimeters to about 90 millimeters, more preferably from about 50 millimeters to about 85 millimeters, and even more preferably from about 50 millimeters to about 80 millimeters. In a further embodiment, the total length of the aerosol-generating article is from about 60 millimeters to about 95 millimeters, preferably from about 60 millimeters to about 90 millimeters, more preferably from about 60 millimeters to about 85 millimeters, and even more preferably from about 60 millimeters to about 80 millimeters. In still further embodiments, the overall length of the aerosol-generating article is from about 70 millimeters to about 95 millimeters, preferably from about 70 millimeters to about 90 millimeters, more preferably from about 70 millimeters to about 85 millimeters, and even more preferably from about 70 millimeters to about 80 millimeters. In an exemplary embodiment, the overall length of the aerosol-generating article is about 75 millimeters.

[0041] Aerosol-generating articles according to the present invention may have an outer diameter of at least 4 millimeters. Preferably, the aerosol-generating article has an outer diameter of at least 5 millimeters. More preferably, the aerosol-generating article has an outer diameter of at least 6 millimeters. Even more preferably, the aerosol-generating article has an outer diameter of at least 7 millimeters.

[0042] Preferably, the aerosol-generating article has an outer diameter of about 12 millimeters or less. More preferably, the aerosol-generating article has an outer diameter of about 10 millimeters or less. Even more preferably, the aerosol-generating article has an outer diameter of about 8 millimeters or less.

[0043] In some embodiments, the aerosol-generating article has an outer diameter of about 4 millimeters to about 12 millimeters, preferably about 5 millimeters to about 12 millimeters, more preferably about 6 millimeters to about 12 millimeters, and even more preferably about 7 millimeters to about 12 millimeters. In other embodiments, the aerosol-generating article has an outer diameter of about 4 millimeters to about 10 millimeters, preferably about 5 millimeters to about 10 millimeters, more preferably about 6 millimeters to about 10 millimeters, and even more preferably about 7 millimeters to about 10 millimeters. In further embodiments, the aerosol-generating article has an outer diameter of about 4 millimeters to about 8 millimeters, preferably about 5 millimeters to about 8 millimeters, more preferably about 6 millimeters to about 8 millimeters, and even more preferably about 7 millimeters to about 8 millimeters.

[0044] The rod of the aerosol-generating substrate may have a length of from about 5 millimeters to about 100 mm.

[0045] In some embodiments, the aerosol-generating substrate rod preferably has a length of at least about 6 millimeters, and more preferably at least about 7 millimeters. In these embodiments, the aerosol-generating substrate rod may have a length of less than about 90 millimeters, preferably less than about 70 millimeters, more preferably less than about 65 millimeters, more preferably less than about 50 millimeters, and most preferably less than 40 millimeters. In particularly preferred embodiments, the aerosol-generating substrate rod has a length of less than about 35 millimeters, more preferably less than 25 millimeters, and even more preferably less than about 20 millimeters. In one embodiment, the aerosol-generating substrate rod may have a length of about 10 millimeters. In one preferred embodiment, the aerosol-generating substrate rod has a length of about 12 millimeters. This may be combined with the overall length of the aerosol-generating article being about 45 millimeters.

[0046] In other embodiments, the aerosol-generating substrate rod preferably has a length of at least about 10 millimeters, more preferably at least about 20 millimeters, and even more preferably at least about 30 millimeters. In these embodiments, the aerosol-generating substrate rod preferably has a length of no more than about 60 millimeters, more preferably no more than about 50 millimeters, and even more preferably no more than about 40 millimeters.

[0047] In a preferred embodiment, the length of the aerosol-generating substrate rod is about 10 mm to about 60 mm, preferably about 20 mm to about 60 mm, and more preferably about 30 mm to about 60 mm. In another embodiment, the length of the aerosol-generating substrate rod is about 10 mm to about 50 mm, preferably about 20 mm to about 50 mm, and more preferably about 30 mm to about 50 mm. In a further embodiment, the length of the aerosol-generating substrate rod is about 10 mm to about 40 mm, preferably about 20 mm to about 40 mm, and more preferably about 40 mm to about 60 mm. In one exemplary embodiment, the length of the aerosol-generating substrate rod is about 35 mm. This may be combined with a total length of about 75 mm for the aerosol-generating article.

[0048] Preferably, the rod of aerosol-generating substrate has a substantially uniform cross section along the length of the rod, and it is particularly preferred that the rod of aerosol-generating substrate has a substantially circular cross section.

[0049] In aerosol-generating articles according to the invention, the density of the aerosol-generating substrate is preferably greater than about 300 milligrams per cubic centimeter. As used herein, with reference to an aerosol-generating substrate of an aerosol-generating article according to the invention, the term "density" refers to the "apparent density" or "volume density" of the substrate, and is equal to the total mass of a given volume of the body of the aerosol-generating substrate (which may be the mass of homogenized plant material, aerosol former, etc., or the mass of a given volume of gel composition) divided by said given volume of the rod of aerosol-generating substrate.

[0050] Thus, for example, the density of the aerosol-generating substrate determines the mass of a given volume of homogenized tobacco material and the efficiency of packaging a given surface area of ​​the homogenized tobacco material. The density of the homogenized tobacco material is usually determined in large part by the type of process used to produce it. Numerous reconstitution processes for producing homogenized tobacco material are known in the art. These include, but are not limited to, papermaking processes of the type described in U.S. Pat. No. 5,724,998, casting processes of the type described in U.S. Pat. No. 5,724,998, dough reconstitution processes of the type described in U.S. Pat. No. 3,894,544, and extrusion processes of the type described in British Patent No. 983,928.

[0051] Generally, the density of homogenized tobacco material produced by the extrusion and soft mass reconstitution processes is greater than the density of homogenized tobacco material produced by the casting process. The density of homogenized tobacco material produced by the extrusion process may be greater than the density of homogenized tobacco material produced by the soft mass reconstitution process.

[0052] By way of example, the density of the aerosol-generating substrate is at least about 310 milligrams per cubic centimeter, or at least about 320 milligrams per cubic centimeter, or at least about 330 milligrams per cubic centimeter.

[0053] In some embodiments, the density of the aerosol-generating substrate is preferably at least about 350 milligrams per cubic centimeter. More preferably, the density of the aerosol-generating substrate is at least about 400 milligrams per cubic centimeter. Even more preferably, the density of the aerosol-generating substrate is at least about 450 milligrams per cubic centimeter. In particularly preferred embodiments, the density of the aerosol-generating substrate is at least about 500 milligrams per cubic centimeter. Preferably, the density of the aerosol-generating substrate is not more than about 1000 milligrams per cubic centimeter, more preferably not more than about 900 milligrams per cubic centimeter, and even more preferably not more than about 800 milligrams per cubic centimeter. As an example, the density of the aerosol-generating substrate may be from about 350 milligrams per cubic centimeter to about 1000 milligrams per cubic centimeter, preferably from about 400 milligrams per cubic centimeter to about 1000 milligrams per cubic centimeter, more preferably from about 450 milligrams per cubic centimeter to about 1000 milligrams per cubic centimeter, even more preferably from about 500 milligrams per cubic centimeter to about 1000 milligrams per cubic centimeter. As another example, the density of the aerosol-generating substrate may be from about 350 milligrams per cubic centimeter to about 900 milligrams per cubic centimeter, preferably from about 400 milligrams per cubic centimeter to about 900 milligrams per cubic centimeter, more preferably from about 450 milligrams per cubic centimeter to about 900 milligrams per cubic centimeter, even more preferably from about 500 milligrams per cubic centimeter to about 900 milligrams per cubic centimeter.By way of further example, the density of the aerosol-generating substrate may be from about 350 milligrams per cubic centimeter to about 800 milligrams per cubic centimeter, preferably from about 400 milligrams per cubic centimeter to about 800 milligrams per cubic centimeter, more preferably from about 450 milligrams per cubic centimeter to about 800 milligrams per cubic centimeter, and even more preferably from about 500 milligrams per cubic centimeter to about 800 milligrams per cubic centimeter.

[0054] In other embodiments, the density of the aerosol-generating substrate is at least about 600 milligrams per cubic centimeter, preferably at least about 700 milligrams per cubic centimeter, more preferably at least about 800 milligrams per cubic centimeter, and even more preferably at least about 900 milligrams per cubic centimeter. In some particularly preferred embodiments, the density of the aerosol-generating substrate is at least about 1 gram per cubic centimeter, preferably at least about 1.1 grams per cubic centimeter, more preferably at least about 1.2 grams per cubic centimeter, and even more preferably at least about 1.3 grams per cubic centimeter. Preferably, the density of the aerosol-generating substrate is not more than about 2.0 grams per cubic centimeter, more preferably not more than about 1.9 grams per cubic centimeter, and even more preferably not more than about 1.8 grams per cubic centimeter. In preferred embodiments, the density of the aerosol-generating substrate is not more than about 1.7 grams per cubic centimeter, more preferably not more than about 1.6 grams per cubic centimeter, and even more preferably not more than about 1.5 grams per cubic centimeter.

[0055] As an example, the density of the aerosol-generating substrate is from about 1 gram per cubic centimeter to about 1.7 grams per cubic centimeter, preferably from about 1.1 grams per cubic centimeter to about 1.7 grams per cubic centimeter, more preferably from about 1.2 grams per cubic centimeter to about 1.7 grams per cubic centimeter, and even more preferably from about 1.3 grams per cubic centimeter to about 1.7 grams per cubic centimeter. As another example, the density of the aerosol-generating substrate is from about 1 gram per cubic centimeter to about 1.6 grams per cubic centimeter, preferably from about 1.1 grams per cubic centimeter to about 1.6 grams per cubic centimeter, more preferably from about 1.2 grams per cubic centimeter to about 1.6 grams per cubic centimeter, and even more preferably from about 1.3 grams per cubic centimeter to about 1.6 grams per cubic centimeter. By way of further example, the density of the aerosol-generating substrate may be from about 1 gram per cubic centimeter to about 1.5 grams per cubic centimeter, preferably from about 1.1 grams per cubic centimeter to about 1.5 grams per cubic centimeter, more preferably from about 1.2 grams per cubic centimeter to about 1.5 grams per cubic centimeter, and even more preferably from about 1.3 grams per cubic centimeter to about 1.5 grams per cubic centimeter.

[0056] The aerosol-generating substrate may be a solid aerosol-generating substrate.

[0057] In certain preferred embodiments, the aerosol-generating substrate comprises homogenized plant material, preferably homogenized tobacco material.

[0058] As used herein, the term "homogenized plant material" encompasses any plant material formed by agglomeration of plant particles. For example, a sheet or web of homogenized tobacco material for an aerosol-generating substrate of the present invention may be formed by agglomerating particles of tobacco material obtained by grinding, crushing, or comminuting plant material and, optionally, one or more of tobacco lamina and tobacco stems. Homogenized plant material may be produced by casting, extrusion, a papermaking process, or any other suitable process known in the art.

[0059] The homogenized plant material may be provided in any suitable form. For example, the homogenized plant material may be in the form of one or more sheets. As used herein with respect to the present invention, the term "sheet" describes a laminar element having a width and length that is substantially greater than its thickness.

[0060] Alternatively, or additionally, the homogenized plant material may be in the form of a plurality of pellets or granules.

[0061] Alternatively, or additionally, the homogenized plant material may be in the form of a plurality of strands, pieces, or fragments. As used herein, the term "strand" describes an elongated element of material having a length substantially greater than its width and thickness. The term "strand" is intended to encompass pieces, fragments, and any other homogenized plant material having a similar morphology. Strands of homogenized plant material may be formed from a sheet of homogenized plant material, for example, by cutting or chopping, or by other methods, such as extrusion methods.

[0062] In some embodiments, the strands may be formed in situ within the aerosol-generating substrate as a result of splitting or cracking of the sheet of homogenized plant material during the formation of the aerosol-generating substrate, e.g., as a result of crimping. The strands of homogenized plant material within the aerosol-generating substrate may be separated from one another. Alternatively, each strand of homogenized plant material within the aerosol-generating substrate may be at least partially connected to adjacent strands along its length. For example, adjacent strands may be connected by one or more fibers. This may occur, for example, when strands are formed due to splitting of the sheet of homogenized plant material during the manufacture of the aerosol-generating substrate, as described above.

[0063] The aerosol-generating substrate is preferably in the form of one or more sheets of homogenized plant material. In various embodiments of the present invention, the one or more sheets of homogenized plant material may be produced by a casting process. In various embodiments of the present invention, the one or more sheets of homogenized plant material may be produced by a papermaking process. The one or more sheets described herein may each individually have a thickness of 100 micrometers to 600 micrometers, preferably 150 micrometers to 300 micrometers, and most preferably 200 micrometers to 250 micrometers. Individual thickness refers to the thickness of an individual sheet, while combined thickness refers to the total thickness of all sheets comprising the aerosol-generating substrate. For example, if the aerosol-generating substrate is formed from two individual sheets, the combined thickness is the thickness of the two individual sheets, or the sum of the measured thicknesses of the two sheets, stacked within the aerosol-generating substrate.

[0064] One or more of the sheets described herein may each individually have a weight of about 100 g / m 2 ~about 300g / m 2 The sheet may have a basis weight of 1000 gram.

[0065] One or more of the sheets described herein may each individually have a density of about 0.3 g / cm 3 ~Approx. 1.3g / cm3 and may have a density of about 0.7 g / cm 3 ~Approx. 1.0g / cm 3 It is preferred that the density of the granular material is 0.05 to 0.15.

[0066] In embodiments of the invention in which the aerosol-generating substrate comprises one or more sheets of homogenized plant material, the sheets are preferably in the form of an assembly of one or more sheets. As used herein, the term "assembly" means that the sheets of homogenized plant material are coiled, folded, or otherwise compressed or contracted in a direction substantially transverse to the cylindrical axis of the plug or rod.

[0067] One or more sheets of homogenized plant material may be gathered transversely to their longitudinal axes and surrounded by a wrapper to form a continuous rod or plug.

[0068] One or more sheets of homogenized plant material may be advantageously crimped or similarly treated. As used herein, the term "crimped" refers to a sheet having a plurality of substantially parallel ridges or corrugations. Alternatively or additionally to being crimped, one or more sheets of homogenized plant material may be embossed, debossed, perforated, or otherwise deformed to provide texture to one or both sides of the sheet.

[0069] Preferably, each sheet of homogenized plant material may be crimped to have a plurality of ridges or corrugations substantially parallel to the cylindrical axis of the plug. This process advantageously facilitates assembling the crimped sheets of homogenized plant material to form a plug. Preferably, one or more sheets of homogenized plant material may be assembled. Of course, the crimped sheets of homogenized plant material may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that form acute or obtuse angles with respect to the cylindrical axis of the plug. The sheet may be crimped to an extent that the integrity of the sheet is interrupted at the plurality of parallel ridges or corrugations, causing separation of the material and resulting in the formation of fragments, strands, or pieces of homogenized plant material.

[0070] Alternatively, one or more sheets of homogenized plant material may be cut into strands, as mentioned above. In such embodiments, the aerosol-generating substrate includes multiple strands of homogenized plant material. The strands can be used to form plugs. Typically, the width of such strands is about 5 millimeters, about 4 millimeters, about 3 millimeters, about 2 millimeters, or less. The length of the strands may be greater than about 5 millimeters, about 5 millimeters to about 15 millimeters, about 8 millimeters to about 12 millimeters, or even about 12 millimeters. Preferably, the strands have substantially the same length as each other. The length of the strands may be determined by the manufacturing process by which the rod is cut into shorter plugs, and the length of the strands corresponds to the length of the plugs. Strands are fragile and may break, especially during transport. In such cases, the length of some of the strands may be shorter than the length of the plugs.

[0071] The strands preferably extend substantially longitudinally along the length of the aerosol-generating substrate, aligned with the longitudinal axis, and are therefore preferably aligned substantially parallel to one another.

[0072] The homogenized plant material may contain up to about 95 weight percent plant particles on a dry weight basis, preferably up to about 90 weight percent plant particles, more preferably up to about 80 weight percent plant particles, more preferably up to about 70 weight percent plant particles, more preferably up to about 60 weight percent plant particles, and even more preferably up to about 50 weight percent plant particles on a dry weight basis.

[0073] For example, the homogenized plant material can contain, on a dry weight basis, from about 2.5 weight percent to about 95 weight percent plant particles, or from about 5 weight percent to about 90 weight percent plant particles, or from about 10 weight percent to about 80 weight percent plant particles, or from about 15 weight percent to about 70 weight percent plant particles, or from about 20 weight percent to about 60 weight percent plant particles, or from about 30 weight percent to about 50 weight percent plant particles.

[0074] In certain embodiments of the present invention, the homogenized plant material is a homogenized tobacco material comprising tobacco particles. The sheets of homogenized tobacco material used in such embodiments of the present invention may have a tobacco content of at least about 40 weight percent on a dry weight basis, more preferably at least about 50 weight percent on a dry weight basis, even more preferably at least about 70 weight percent on a dry weight basis, and most preferably at least about 90 weight percent on a dry weight basis.

[0075] For purposes of the present invention, the term "tobacco particles" describes particles of any plant material of the Nicotiana species. The term "tobacco particles" encompasses ground or powdered tobacco lamina, ground or powdered tobacco stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. In preferred embodiments, the tobacco particles are derived substantially entirely from tobacco lamina. In contrast, isolated nicotine and nicotine salts, although tobacco-derived compounds, are not considered tobacco particles for purposes of the present invention and are not included in the proportion of particulate plant material.

[0076] The tobacco particles may be prepared from one or more tobacco plant varieties. Any type of tobacco may be used in the blend. Examples of types of tobacco materials that may be used include, but are not limited to, sun-cured tobacco, flue-cured tobacco, burley tobacco, Maryland tobacco, Orient tobacco, Virginia tobacco, and other specialty tobaccos.

[0077] Flame-curing is a tobacco curing method used specifically with Virginia tobacco. During the flue-curing process, heated air is circulated through tightly packed tobacco. During the first stage, the tobacco leaves yellow and wither. During the second stage, the leaf lamina dries completely. During the third stage, the leaf stem dries completely.

[0078] Burley tobacco plays an important role in many tobacco blends. It has a unique flavor and aroma and the ability to absorb large amounts of casing.

[0079] Orient is a type of tobacco with small leaves and high aromatic qualities. However, Orient tobacco has a milder flavor than, for example, Burley. Therefore, Orient tobacco is generally used in relatively small proportions in tobacco blends.

[0080] Kasturi, Madura, and Jatim are subtypes of sun-cured tobacco that can be used. Preferably, Kasturi and flue-cured tobaccos are blended to produce tobacco particles. Thus, the tobacco particles in the particulate plant material can comprise a blend of Kasturi and flue-cured tobaccos.

[0081] The tobacco particles may have a nicotine content of at least about 2.5 weight percent on a dry weight basis, more preferably at least about 3 weight percent, even more preferably at least about 3.2 weight percent, even more preferably at least about 3.5 weight percent, and most preferably at least about 4 weight percent on a dry weight basis.

[0082] In certain other embodiments of the present invention, the homogenized plant material comprises tobacco particles in combination with non-tobacco plant flavor particles. Preferably, the non-tobacco plant flavor particles are selected from one or more of ginger particles, eucalyptus particles, clove particles, and star anise particles. Preferably, in these embodiments, the homogenized plant material comprises, on a dry weight basis, at least about 2.5 weight percent of non-tobacco plant flavor particles, with the remaining plant particles being tobacco particles. Preferably, the homogenized plant material comprises, on a dry weight basis, at least about 4 weight percent of non-tobacco plant flavor particles, more preferably at least about 6 weight percent of non-tobacco plant flavor particles, more preferably at least about 8 weight percent of non-tobacco plant flavor particles, and more preferably at least about 10 weight percent of non-tobacco plant flavor particles. Preferably, the homogenized plant material comprises, on a dry weight basis, at most about 20 weight percent of non-tobacco plant flavor particles, more preferably at most about 18 weight percent of non-tobacco plant flavor particles, and more preferably at most about 16 weight percent of non-tobacco plant flavor particles.

[0083] The weight ratio of non-tobacco plant flavor particles to tobacco particles in the particulate plant material forming the homogenized plant material can vary depending on the desired flavor characteristics and composition of the aerosol generated from the aerosol-generating substrate during use. Preferably, the homogenized plant material comprises, on a dry weight basis, at least a 1:30 weight ratio of non-tobacco plant flavor particles to tobacco particles, more preferably at least a 1:20 weight ratio of non-tobacco plant flavor particles to tobacco particles, more preferably at least a 1:10 weight ratio of non-tobacco plant flavor particles to tobacco particles, and most preferably at least a 1:5 weight ratio of non-tobacco plant flavor particles to tobacco particles.

[0084] Alternatively, or in addition to including tobacco particles in the homogenized plant material of the aerosol-generating substrate according to the present invention, the homogenized plant material may include cannabis particles. The term "cannabis particles" refers to particles of cannabis plants, such as Cannabis sativa, Cannabis indica, and Cannabis ruderalis.

[0085] The homogenized plant material preferably comprises no more than 95 weight percent particulate plant material on a dry weight basis. Accordingly, the particulate plant material is typically combined with one or more other ingredients to form the homogenized plant material.

[0086] The homogenized plant material may further comprise a binder for modifying the mechanical properties of the particulate plant material, wherein the binder is included in the homogenized plant material during production as described herein. Suitable exogenous binders known to those skilled in the art are known in the art and include, but are not limited to, gums such as guar gum, xanthan gum, gum arabic, and locust bean gum; cellulose binders such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose; polysaccharides such as starch, organic acids such as alginic acid, sodium alginate, agar, and conjugate base salts of organic acids such as pectin, and combinations thereof. Preferably, the binder comprises guar gum.

[0087] The binder may be present in an amount of about 1 weight percent to about 10 weight percent based on the dry weight of the homogenized plant material, preferably in an amount of about 2 weight percent to about 5 weight percent based on the dry weight of the homogenized plant material.

[0088] Alternatively, or additionally, the homogenized plant material may further comprise one or more lipids to enhance the diffusion rate of the volatile components (e.g., aerosol formers, gingerol, and nicotine), where the lipids are included in the homogenized plant material during the processes described herein. Suitable lipids for inclusion in the homogenized plant material include, but are not limited to, medium chain triglycerides, cocoa butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil, cottonseed oil, coconut oil, hydrogenated coconut oil, candelilla wax, carnauba wax, shellac, sunflower wax, sunflower oil, rice bran, and Revel A, and combinations thereof.

[0089] Alternatively, or additionally, the homogenized plant material may further comprise a pH adjuster.

[0090] Alternatively, or in addition, the homogenized plant material may further comprise fibers to alter the mechanical properties of the homogenized plant material, where the fibers are included in the homogenized plant material during the processes described herein. Suitable exogenous fibers for inclusion in the homogenized plant material are known in the art and include fibers formed from non-tobacco and non-ginger materials, including, but not limited to, cellulose fibers, soft wood fibers, hard wood fibers, jute fibers, and combinations thereof. Exogenous fibers derived from tobacco and / or ginger may also be added. Any fibers added to the homogenized plant material are not considered to form part of the "particulate plant material" defined above. Prior to inclusion in the homogenized plant material, the fibers may be processed by a suitable process known in the art, including, but not limited to, mechanical pulping, refining, chemical pulping, bleaching, sulfate pulping, and combinations thereof. Typically, the fibers have a length greater than their width.

[0091] Suitable fibers are typically greater than 400 micrometers and have a length of 4 millimeters or less, with lengths in the range of 0.7 millimeters to 4 millimeters being preferred. The fibers are preferably present in an amount of about 2 weight percent to about 15 weight percent, most preferably about 4 weight percent, based on the dry weight of the substrate.

[0092] Alternatively, or in addition, the homogenized plant material may further comprise one or more aerosol formers. Upon volatilization, the aerosol formers can carry other vaporized compounds, such as nicotine and flavorants, that are released from the aerosol-generating substrate upon heating. Suitable aerosol formers for inclusion in the homogenized plant material are known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol mono-, di-, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and tetradecanedioate).

[0093] The homogenized plant material may have an aerosol former content of from about 5 weight percent to about 30 weight percent on a dry weight basis, such as from about 10 weight percent to about 25 weight percent on a dry weight basis, or from about 15 weight percent to about 20 weight percent on a dry weight basis.

[0094] For example, when the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, the aerosol former content may preferably be about 5 weight percent to about 30 weight percent on a dry weight basis.When the substrate is intended for use in an aerosol-generating article for an electrically-operated aerosol-generating system having a heating element, the aerosol former is preferably glycerol.

[0095] In other embodiments, the homogenized plant material may have an aerosol former content of about 1 percent to about 5 percent by weight on a dry weight basis. For example, if the substrate is intended for use in an aerosol-generating article in which the aerosol former is held in a reservoir separate from the substrate, the substrate may have an aerosol former content of greater than 1 percent and less than about 5 percent. In such embodiments, the aerosol former volatilizes upon heating, and the aerosol former stream contacts the aerosol-generating substrate in a manner that incorporates flavors from the aerosol-generating substrate into the aerosol.

[0096] In other embodiments, the homogenized plant material may have an aerosol former content of about 30 weight percent to about 45 weight percent. This relatively high level of aerosol former is particularly suitable for aerosol-generating substrates intended to be heated at temperatures below 275 degrees Celsius. In such embodiments, the homogenized plant material preferably further comprises, on a dry weight basis, about 2 weight percent to about 10 weight percent of a cellulose ether and, on a dry weight basis, about 5 weight percent to about 50 weight percent of additional cellulose. The use of a combination of a cellulose ether and additional cellulose has been found to result in particularly effective aerosol delivery when used in aerosol-generating substrates having an aerosol former content of 30 weight percent to 45 weight percent.

[0097] Suitable cellulose ethers include, but are not limited to, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, hydroxyl ethyl cellulose, hydroxyl propyl cellulose, ethyl hydroxyl ethyl cellulose and carboxymethyl cellulose (CMC). In a particularly preferred embodiment, the cellulose ether is carboxymethyl cellulose.

[0098] As used herein, the term "additional cellulose" encompasses any cellulose material incorporated into the homogenized plant material that is not derived from the non-tobacco plant particles or tobacco particles provided therein. Thus, the additional cellulose is incorporated into the homogenized plant material as a separate and distinct cellulose source in addition to the non-tobacco plant material or tobacco material, relative to any cellulose inherently provided within the non-tobacco plant particles or tobacco particles. The additional cellulose is typically derived from a plant different from the non-tobacco plant particles or tobacco particles. Preferably, the additional cellulose is in the form of an inert cellulose material that is sensorily inert and therefore does not substantially affect the sensory properties of the aerosol generated from the aerosol-generating substrate. For example, the additional cellulose is preferably a tasteless and odorless material.

[0099] The additional cellulose may include cellulose powder, cellulose fiber, or a combination thereof.

[0100] The aerosol former may act as a wetting agent in the aerosol-generating substrate.

[0101] In certain preferred embodiments of the present invention, the aerosol-generating substrate comprises a gel composition comprising an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound, hi particularly preferred embodiments, the aerosol-generating substrate comprises a gel composition comprising nicotine.

[0102] Preferably, the gel composition comprises an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound, an aerosol former, and at least one gelling agent. Preferably, the at least one gelling agent forms a solid medium, the glycerol is dispersed in the solid medium, and the alkaloid or cannabinoid is dispersed in the glycerol. Preferably, the gel composition is in a stable gel phase.

[0103] Advantageously, the stable gel composition comprising nicotine provides a predictable composition shape upon storage or during transition from manufacture to consumer. The stable gel composition comprising nicotine substantially maintains its shape. The stable gel composition comprising nicotine does not substantially release a liquid phase upon storage or during transition from manufacture to consumer. The stable gel composition comprising nicotine may provide a simple consumable design. The consumable may not need to be designed to contain a liquid, and therefore a wider range of materials and container configurations may be contemplated.

[0104] The gel compositions described herein may be combined with an aerosol generating device to provide nicotine aerosol to the lungs at inhalation or airflow rates within those of traditional smoking. The aerosol generating device may continuously heat the gel composition. The consumer may take multiple inhalations or "puffs," with each "puff" delivering a quantity of nicotine aerosol. Upon heating, the gel composition may deliver a high-nicotine / low total particulate matter (TPM) aerosol to the consumer, preferably in a continuous manner.

[0105] The phrase "stable gel phase" or "stable gel" refers to a gel that substantially maintains its shape and mass when exposed to various environmental conditions. A stable gel cannot substantially release or absorb water (sweat) when exposed to standard temperatures and pressures while varying relative humidity from about 10 percent to about 60 percent. For example, a stable gel can substantially maintain its shape and mass when exposed to standard temperatures and pressures while varying relative humidity from about 10 percent to about 60 percent.

[0106] The gel composition may contain an alkaloid compound, or a cannabinoid compound, or both an alkaloid compound and a cannabinoid compound. The gel composition may contain one or more alkaloids. The gel composition may contain one or more cannabinoids. The gel composition may contain a combination of one or more alkaloids and one or more cannabinoids.

[0107] The term "alkaloid compound" refers to any class of naturally occurring organic compounds containing one or more basic nitrogen atoms. Generally, alkaloids contain at least one nitrogen atom in an amine-type structure. This or another nitrogen atom within the molecule of an alkaloid compound can be active as a base in an acid-base reaction. Most alkaloid compounds have one or more of their nitrogen atoms as part of a ring system, such as a heterocycle. In nature, alkaloid compounds are found primarily in plants and are particularly common in certain families of flowering plants. However, some alkaloid compounds are found in animal species and fungi. In this disclosure, the term "alkaloid compound" refers to both naturally occurring and synthetically produced alkaloid compounds.

[0108] The gel composition preferably comprises an alkaloid compound selected from the group consisting of nicotine, anatabine, and combinations thereof.

[0109] Preferably, the gel composition comprises nicotine.

[0110] The term "nicotine" refers to nicotine and nicotine derivatives (eg, free base nicotine, nicotine salts, and the like).

[0111] The term "cannabinoid compounds" refers to any one of a class of naturally occurring compounds found in parts of the cannabis plant, including Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Cannabinoid compounds are particularly concentrated in the female flower heads. Cannabinoid compounds that occur naturally in cannabis plants include cannabidiol (CBD) and tetrahydrocannabinol (THC). In this disclosure, the term "cannabinoid compounds" is used to describe both naturally occurring and synthetically produced cannabinoid compounds.

[0112] The gel may comprise a cannabinoid compound selected from the group consisting of cannabidiol (CBD), tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), cannabichromene (CBC), cannabicyclol (CBL), cannabivarin (CBV), tetrahydrocannabivarin (THCV), cannabidivarin (CBDV), cannabichromevarin (CBCV), cannabigerovarin (CBGV), cannabigerol monomethyl ether (CBGM), cannabielsoin (CBE), cannabicitran (CBT), and combinations thereof.

[0113] The gel composition may preferably comprise a cannabinoid compound selected from the group consisting of cannabidiol (CBD), THC (tetrahydrocannabinol) and combinations thereof.

[0114] The gel may preferably contain cannabidiol (CBD).

[0115] The gel composition may include nicotine and cannabidiol (CBD).

[0116] The gel composition may include nicotine, cannabidiol (CBD), and THC (tetrahydrocannabinol).

[0117] The gel composition preferably contains about 0.5 to about 10 weight percent alkaloid compounds, or about 0.5 to about 10 weight percent cannabinoid compounds, or a total of about 0.5 to about 10 weight percent alkaloid and cannabinoid compounds. The gel composition may contain about 0.5 to about 5 weight percent alkaloid compounds, or about 0.5 to about 5 weight percent cannabinoid compounds, or a total of about 0.5 to about 5 weight percent alkaloid and cannabinoid compounds. The gel composition preferably contains about 1 to about 3 weight percent alkaloid compounds, or about 1 to about 3 weight percent cannabinoid compounds, or a total of about 1 to about 3 weight percent alkaloid and cannabinoid compounds. The gel composition may preferably contain about 1.5 weight percent to about 2.5 weight percent alkaloid compounds, or about 1.5 weight percent to about 2.5 weight percent cannabinoid compounds, or a total amount of about 1.5 weight percent to about 2.5 weight percent alkaloid compounds and cannabinoid compounds. The gel composition may preferably contain about 2 weight percent alkaloid compounds, or about 2 weight percent cannabinoid compounds, or a total amount of about 2 weight percent alkaloid compounds and cannabinoid compounds. The alkaloid compound component of the gel formulation may be the most volatile component of the gel formulation. In some embodiments, water may be the most volatile component of the gel formulation, and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation. The cannabinoid compound component of the gel formulation may be the most volatile component of the gel formulation. In some embodiments, water may be the most volatile component of the gel formulation, and the alkaloid compound component of the gel formulation may be the second most volatile component of the gel formulation.

[0118] Preferably, nicotine is included in the gel composition. Nicotine can be added to the composition in free base or salt form. The gel composition contains about 0.5 weight percent to about 10 weight percent nicotine, or about 0.5 weight percent to about 5 weight percent nicotine. Preferably, the gel composition contains about 1 weight percent to about 3 weight percent nicotine, or about 1.5 weight percent to about 2.5 weight percent nicotine, or about 2 weight percent nicotine. The nicotine component of the gel formulation can be the most volatile component of the gel formulation. In some embodiments, water can be the most volatile component of the gel formulation, and the nicotine component of the gel formulation can be the second most volatile component of the gel formulation.

[0119] The gel composition includes an aerosol former. Ideally, the aerosol former is substantially resistant to thermal degradation at the operating temperature of the associated aerosol-generating device. Suitable aerosol formers include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate). The polyhydric alcohol or mixture thereof can be one or more of triethylene glycol, 1,3-butanediol, and glycerin (glycerol or propane-1,2,3-triol) or polyethylene glycol. The aerosol former is preferably glycerol.

[0120] The gel composition comprises a majority of the aerosol former. The gel composition may comprise a mixture of water and aerosol former, with the aerosol former forming a majority (by weight) of the gel composition. The aerosol former may form at least about 50 weight percent of the gel composition. The aerosol former may form at least about 60 weight percent, or at least about 65 weight percent, or at least about 70 weight percent of the gel composition. The aerosol former may form about 70 weight percent to about 80 weight percent of the gel composition. The aerosol former may form about 70 weight percent to about 75 weight percent of the gel composition.

[0121] The gel composition may comprise a majority of glycerol. The gel composition may comprise a mixture of water and glycerol, with glycerol forming the majority (by weight) of the gel composition. Glycerol may form at least about 50 weight percent of the gel composition. Glycerol may form at least about 60 weight percent, or at least about 65 weight percent, or at least about 70 weight percent of the gel composition. Glycerol may form about 70 weight percent to about 80 weight percent of the gel composition. Glycerol may form about 70 weight percent to about 75 weight percent of the gel composition.

[0122] The gel composition preferably includes at least one gelling agent. The gel composition preferably includes a total amount of gelling agents ranging from about 0.4 weight percent to about 10 weight percent. More preferably, the composition includes gelling agents in a range of about 0.5 weight percent to about 8 weight percent. More preferably, the composition includes gelling agents in a range of about 1 weight percent to about 6 weight percent. More preferably, the composition includes gelling agents in a range of about 2 weight percent to about 4 weight percent. More preferably, the composition includes gelling agents in a range of about 2 weight percent to about 3 weight percent.

[0123] The term "gelling agent" refers to a compound that, when homogeneously added in an amount of about 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture, forms a solid medium or support matrix leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond cross-linking gelling agents and ionic cross-linking gelling agents.

[0124] The gelling agent may comprise one or more biopolymers, which may be formed from polysaccharides.

[0125] Examples of biopolymers include gellan gum (natural gellan gum, low acyl gellan gum, high acyl gellan gum, and low acyl gellan gum are preferred), xanthan gum, alginate (alginic acid), agar, and guar gum. It may be preferable for the composition to include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include two biopolymers in substantially equal amounts by weight. The composition may include three biopolymers in substantially equal amounts by weight.

[0126] Preferably, the gel composition contains at least about 0.2 weight percent of the hydrogen-bond cross-linked gelling agent. Alternatively, or additionally, the gel composition preferably contains at least about 0.2 weight percent of the ionic cross-linked gelling agent. Most preferably, the gel composition contains at least about 0.2 weight percent of the hydrogen-bond cross-linked gelling agent and at least about 0.2 weight percent of the ionic cross-linked gelling agent. The gel composition may contain from about 0.5 weight percent to about 3 weight percent of the hydrogen-bond cross-linked gelling agent and from about 0.5 weight percent to about 3 weight percent of the ionic cross-linked gelling agent, or from about 1 weight percent to about 2 weight percent of the hydrogen-bond cross-linked gelling agent and from about 1 weight percent to about 2 weight percent of the ionic cross-linked gelling agent. The hydrogen-bond cross-linked gelling agent and the ionic cross-linked gelling agent may be present in substantially equal amounts in the gel composition.

[0127] The term "hydrogen-bond cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links via hydrogen bonds. Hydrogen bonds are not covalent bonds to hydrogen atoms, but rather a type of electrostatic dipole-dipole attraction between molecules. They result from the attraction between a hydrogen atom covalently bonded to another extremely electronegative atom, such as an N, O, or F atom, and another extremely electronegative atom.

[0128] The hydrogen-bond cross-linking gelling agent may comprise one or more of galactomannan, gelatin, agarose, or konjac gum, or agar. Preferably, the hydrogen-bond cross-linking gelling agent comprises agar.

[0129] The gel composition preferably contains from about 0.3 weight percent to about 5 weight percent of the hydrogen-bond cross-linking gelling agent. Preferably, the composition contains from about 0.5 weight percent to about 3 weight percent of the hydrogen-bond cross-linking gelling agent. Preferably, the composition contains from about 1 weight percent to about 2 weight percent of the hydrogen-bond cross-linking gelling agent.

[0130] The gel composition may contain galactomannan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the galactomannan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the galactomannan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the galactomannan may be in the range of about 1 weight percent to about 2 weight percent.

[0131] The gel composition may contain gelatin in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the gelatin may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the gelatin may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the gelatin may be in the range of about 1 weight percent to about 2 weight percent.

[0132] The gel composition may contain agarose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the agarose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the agarose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the agarose may be in the range of about 1 weight percent to about 2 weight percent.

[0133] The gel composition may contain konjac gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the konjac gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the konjac gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the konjac gum may be in the range of about 1 weight percent to about 2 weight percent.

[0134] The gel composition may contain agar in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the agar may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the agar may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the agar may be in the range of about 1 weight percent to about 2 weight percent.

[0135] The term "ionically cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links through ionic bonds. Ionic cross-linking involves the association of polymer chains through non-covalent interactions. A cross-linked network is formed when multivalent molecules with opposite charges are electrostatically attracted to each other, resulting in a cross-linked polymer network.

[0136] The ionic cross-linking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. Preferably, the ionic cross-linking gelling agent may include low acyl gellan.

[0137] The gel composition may comprise an ionically cross-linked gelling agent in the range of about 0.3 weight percent to about 5 weight percent. Preferably, the composition comprises an ionically cross-linked gelling agent in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the composition comprises an ionically cross-linked gelling agent in the range of about 1 weight percent to about 2 weight percent.

[0138] The gel composition may contain low acyl gellan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the low acyl gellan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the low acyl gellan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the low acyl gellan may be in the range of about 1 weight percent to about 2 weight percent.

[0139] The gel composition may comprise pectin in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the pectin may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the pectin may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the pectin may be in the range of about 1 weight percent to about 2 weight percent.

[0140] The gel composition may comprise kappa carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the kappa carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the kappa carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the kappa carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0141] The gel composition may comprise iota carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the iota carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the iota carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the iota carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0142] The gel composition may comprise alginate in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the alginate may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the alginate may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the alginate may be in the range of about 1 weight percent to about 2 weight percent.

[0143] The gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 3:1 to about 1:3. Preferably, the gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 2:1 to about 1:2. Preferably, the gel composition may contain a hydrogen-bond cross-linking gelator and an ionic cross-linking gelator in a ratio of about 1:1.

[0144] The gel composition may further comprise a thickening agent. The thickening agent in combination with the hydrogen-bond cross-linking gelling agent and the ionic cross-linking gelling agent surprisingly appears to support a solid medium and maintain the gel composition even when the gel composition contains high levels of glycerol.

[0145] The term "thickener" refers to a compound that, when uniformly added in an amount of 0.3 weight percent into a 50 weight percent water / 50 weight percent glycerol mixture at 25°C, increases the viscosity without resulting in the formation of a gel, and the mixture remains or becomes fluid. Preferably, the thickener, when uniformly added in an amount of 0.3 weight percent into a 50 weight percent water / 50 weight percent glycerol mixture at 25°C, increases the viscosity of the mixture without resulting in the formation of a gel, and the mixture remains or becomes fluid. -1Preferably, the thickener, when homogeneously added in an amount of 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture at 25° C., increases the viscosity by 0.1 s at a shear rate of 0.3 weight percent, preferably at least 500 cPs, preferably at least 1000 cPs, without causing the formation of a gel, and the mixture remains fluid. -1 refers to a compound that increases the viscosity of a mixture at a shear rate of at least 2, at least 5, at least 10, or at least 100 times greater than before addition, and that causes the mixture to become or remain fluid.

[0146] The viscosity values ​​recited herein may be measured using a Brookfield RVT viscometer with a disc type RV#2 spindle rotating at 25° C. at a speed of 6 revolutions per minute (rpm).

[0147] The gel composition preferably comprises a thickening agent in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the composition comprises a thickening agent in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the composition comprises a thickening agent in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the composition comprises a thickening agent in the range of about 1 weight percent to about 2 weight percent.

[0148] The thickening agent may comprise one or more of xanthan gum, carboxymethylcellulose, microcrystalline cellulose, methylcellulose, gum arabic, guar gum, lambda carrageenan, or starch. Preferably, the thickening agent may comprise xanthan gum.

[0149] The gel composition may contain xanthan gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the xanthan gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the xanthan gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the xanthan gum may be in the range of about 1 weight percent to about 2 weight percent.

[0150] The gel composition may contain carboxymethylcellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the carboxymethylcellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0151] The gel composition may contain microcrystalline cellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the microcrystalline cellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0152] The gel composition may contain methylcellulose in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the methylcellulose may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the methylcellulose may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the methylcellulose may be in the range of about 1 weight percent to about 2 weight percent.

[0153] The gel composition may include gum arabic in the range of about 0.2 weight percent to about 5 weight percent. Preferably, gum arabic may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, gum arabic may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, gum arabic may be in the range of about 1 weight percent to about 2 weight percent.

[0154] The gel composition may contain guar gum in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the guar gum may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the guar gum may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the guar gum may be in the range of about 1 weight percent to about 2 weight percent.

[0155] The gel composition may comprise lambda carrageenan in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the lambda carrageenan may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the lambda carrageenan may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the lambda carrageenan may be in the range of about 1 weight percent to about 2 weight percent.

[0156] The gel composition may comprise starch in the range of about 0.2 weight percent to about 5 weight percent. Preferably, the starch may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the starch may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the starch may be in the range of about 1 weight percent to about 2 weight percent.

[0157] The gel composition may further comprise a divalent cation. Preferably, the divalent cation comprises calcium ions, such as calcium lactate in solution. The divalent cation (e.g., calcium ions) may aid in gel formation in compositions that include a gelling agent, such as an ionically crosslinking gelling agent. Ionic effects may aid gel formation. The divalent cation may be present in the gel composition in a range of about 0.1 to about 1 weight percent, or about 0.5 weight percent.

[0158] The gel composition may further comprise an acid. The acid may comprise a carboxylic acid. The carboxylic acid may comprise a ketone group. Preferably, the carboxylic acid may comprise a ketone group having less than about 10 carbon atoms, such as levulinic acid or lactic acid, or less than about 6 carbon atoms, or less than about 4 carbon atoms. Preferably, the carboxylic acid has three carbon atoms (such as lactic acid). Lactic acid surprisingly improves the stability of the gel composition over similar carboxylic acids. The carboxylic acid may aid in gel formation. The carboxylic acid may reduce changes in the alkaloid compound concentration, or cannabinoid compound concentration, or both the alkaloid compound concentration and the cannabinoid compound concentration in the gel composition during storage. The carboxylic acid may reduce changes in the nicotine concentration in the gel composition during storage.

[0159] The gel composition may include a carboxylic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the carboxylic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the carboxylic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the carboxylic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0160] The gel composition may contain lactic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the lactic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the lactic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the lactic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0161] The gel composition may include levulinic acid in the range of about 0.1 weight percent to about 5 weight percent. Preferably, the levulinic acid may be in the range of about 0.5 weight percent to about 3 weight percent. Preferably, the levulinic acid may be in the range of about 0.5 weight percent to about 2 weight percent. Preferably, the levulinic acid may be in the range of about 1 weight percent to about 2 weight percent.

[0162] The gel composition preferably contains some water. When the composition contains some water, the gel composition is more stable. The gel composition preferably contains at least about 1 weight percent, or at least about 2 weight percent, or at least about 5 weight percent water. The gel composition preferably contains at least about 10 weight percent or at least about 15 weight percent water.

[0163] The gel composition preferably contains about 8 weight percent to about 32 weight percent water. The gel composition preferably contains about 15 weight percent to about 25 weight percent water. The gel composition preferably contains about 18 weight percent to about 22 weight percent water. The gel composition preferably contains about 20 weight percent water.

[0164] Preferably, the aerosol-generating substrate contains about 150 mg to about 350 mg of the gel composition.

[0165] Preferably, the aerosol-generating substrate comprises a porous medium loaded with a gel composition. An advantage of a porous medium loaded with a gel composition is that the gel composition is retained within the porous medium, which may aid in the manufacture, storage, or transportation of the gel composition. This may help maintain the desired shape of the gel composition, particularly during manufacture, transportation, or use.

[0166] The porous medium can be any suitable porous material capable of holding or retaining the gel composition. Ideally, the porous medium can allow the gel composition to move within it. In certain embodiments, the porous medium comprises natural, synthetic, or semi-synthetic materials, or a combination thereof. In certain embodiments, the porous medium comprises a sheet material, a foam, or a fiber, e.g., loose fiber, or a combination thereof. In certain embodiments, the porous medium comprises a woven fabric, a nonwoven fabric, or an extruded material, or a combination thereof. Preferably, the porous medium comprises cotton, paper, viscose, PLA, or cellulose acetate, or a combination thereof. Preferably, the porous medium comprises a sheet material, e.g., cotton or cellulose acetate. In a particularly preferred embodiment, the porous medium comprises a sheet made from cotton fibers.

[0167] The porous media used in the present invention may be crimped or chopped. In a preferred embodiment, the porous media is crimped. In an alternative embodiment, the porous media comprises chopped porous media. The crimping or chopping process can be before or after loading the gel composition.

[0168] Crimping the sheet material has the advantage of improving the structure and allowing passageways through the structure. The passageways through the crimped sheet material aid in gel loading, gel retention, and fluid passage through the crimped sheet material. Therefore, there are advantages to using crimped sheet materials as porous media.

[0169] The shredding provides the medium with a high surface area to volume ratio so that it can readily absorb the gel.

[0170] In certain embodiments, the sheet material is a composite material. Preferably, the sheet material is porous. The sheet material may aid in the manufacture of the tubular element containing the gel. The sheet material may aid in the introduction of an active agent into the tubular element containing the gel. The sheet material may help stabilize the structure of the tubular element containing the gel. The sheet material may aid in the transportation or storage of the gel. The use of the sheet material allows or aids in adding structure to the porous medium, for example, by crimping the sheet material.

[0171] The porous medium can be a thread. The thread can include, for example, cotton, paper, or acetate tow. The thread can also be loaded with a gel, like any other porous medium. An advantage of using thread as the porous medium is that it can aid in ease of manufacturing.

[0172] The thread may be loaded with gel by any known means. The thread may simply be coated with gel, or the thread may be impregnated with gel. In manufacturing, the thread may be impregnated with gel and stored ready to be used for inclusion in the assembly of tubular elements.

[0173] The porous medium loaded with the gel composition is preferably provided within a tubular element that forms part of the aerosol-generating article. The term "tubular element" is used to describe a component suitable for use in an aerosol-generating article. Ideally, the tubular element has a longitudinal length greater than its width, but this is not necessary, as the tubular element may be part of a multi-component item whose longitudinal length is ideally greater than its width. Typically, the tubular element is cylindrical, but this is not necessarily the case. For example, the tubular element may have an elliptical, polygonal, such as triangular or rectangular, or irregular cross-section.

[0174] The tubular element preferably includes a first longitudinal passage. The tubular element is preferably formed from a wrapper that defines the first longitudinal passage. The wrapper is preferably a water-resistant wrapper. This water-resistant property of the wrapper can be achieved by using a water-resistant material or by treating the wrapper material. This can be achieved by treating one or both sides of the wrapper. Being water-resistant helps to prevent loss of structure, rigidity, or stiffness. This can also help prevent leakage of gel or liquid, especially if a fluid-structured gel is used.

[0175] In some embodiments, the rod of aerosol-generating substrate further comprises a susceptor element disposed within the aerosol-generating substrate. Indeed, in some embodiments of aerosol-generating articles according to the invention, the susceptor element, e.g., an elongated susceptor, is disposed substantially on the rod of the aerosol-generating substrate such that the susceptor element is in thermal contact with the aerosol-generating substrate.

[0176] As used herein with respect to the present invention, the term "susceptor" refers to a material capable of converting electromagnetic energy into heat. When located within a varying electromagnetic field, induced eddy currents in the susceptor cause the susceptor to heat. The elongated susceptor is located in thermal contact with an aerosol-generating substrate, which is heated by the susceptor.

[0177] The susceptor elements are preferably in the form of elongated susceptors. When used to describe a susceptor, the term "elongated" means that the susceptor has a length dimension that is greater than its width or its thickness, for example, greater than twice its width or its thickness.

[0178] The elongated susceptor is preferably disposed substantially longitudinally within the rod, meaning that the length dimension of the elongated susceptor is aligned approximately parallel to the longitudinal direction of the rod, for example, within ±10 degrees of parallel to the longitudinal direction of the rod. In a preferred embodiment, the elongated susceptor may be positioned at a radially central location within the rod, extending along the longitudinal axis of the rod.

[0179] Preferably, the elongated susceptor extends all the way to the downstream end of the rod of aerosol-generating articles. In some embodiments, the susceptor may extend all the way to the upstream end of the rod of aerosol-generating articles. In particularly preferred embodiments, the susceptor has substantially the same length as the rod of aerosol-generating substrate, extending from the upstream end of the rod to the downstream end of the rod.

[0180] The susceptor is preferably in the form of a pin, rod, strip or blade.

[0181] The susceptor preferably has a length of about 5 millimeters to about 15 millimeters, such as, for example, about 6 millimeters to about 12 millimeters, or about 8 millimeters to about 10 millimeters.

[0182] The ratio between the length of the susceptor and the overall length of the aerosol-generating article may be from about 0.2 to about 0.35.

[0183] In some embodiments, the ratio between the length of the susceptor and the overall length of the aerosol-generating article is at least about 0.22, more preferably at least about 0.24, and even more preferably at least about 0.26. The ratio between the length of the susceptor and the overall length of the aerosol-generating article is preferably less than about 0.34, more preferably less than about 0.32, and even more preferably less than about 0.3. In other embodiments, the ratio between the length of the susceptor and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.34, more preferably from about 0.24 to about 0.34, and even more preferably from about 0.26 to about 0.34. In further embodiments, the ratio between the length of the susceptor and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.32, more preferably from about 0.24 to about 0.32, and even more preferably from about 0.26 to about 0.32. In still further embodiments, the ratio between the length of the susceptor and the overall length of the aerosol-generating article is preferably from about 0.22 to about 0.3, more preferably from about 0.24 to about 0.3, and even more preferably from about 0.26 to about 0.3.

[0184] In a particularly preferred embodiment, the ratio between the length of the susceptor and the overall length of the aerosol-generating article is about 0.27.

[0185] The susceptor preferably has a width of about 1 mm to about 5 mm.

[0186] The susceptor generally has a thickness of about 0.01 millimeters to about 2 millimeters, for example, about 0.5 millimeters to about 2 millimeters. In some embodiments, the susceptor preferably has a thickness of about 10 micrometers to about 500 micrometers, more preferably about 10 micrometers to about 100 micrometers.

[0187] When the susceptor has a constant cross section, for example a circular cross section, it has a preferred width or diameter of about 1 millimeter to about 5 millimeters.

[0188] When the susceptor is in the form of a strip or blade, the strip or blade preferably has a rectangular shape with a width of about 2 to about 8 millimeters, more preferably about 3 to about 5 millimeters. As an example, a susceptor in the form of a blade strip may have a width of about 4 millimeters.

[0189] When the susceptor is in the form of a strip or blade, the strip or blade preferably has a rectangular shape and a thickness of about 0.03 millimeters to about 0.15 millimeters, more preferably about 0.05 millimeters to about 0.09 millimeters. As an example, a susceptor in the form of a blade strip may have a thickness of about 0.07 millimeters.

[0190] In a preferred embodiment, the elongated susceptor is provided in the form of a strip or blade, preferably having a rectangular shape and a thickness of about 55 micrometers to about 65 micrometers.

[0191] More preferably, the elongated susceptor has a thickness of about 57 micrometers to about 63 micrometers. Even more preferably, the elongated susceptor has a thickness of about 58 micrometers to about 62 micrometers. In a particularly preferred embodiment, the elongated susceptor has a thickness of about 60 micrometers.

[0192] While not wishing to be bound by theory, the inventors believe that, overall, the selection of a given susceptor thickness is also influenced by the constraints set by the selected length and width of the susceptor, as well as the constraints set by the geometry and dimensions of the rod of the aerosol-generating substrate. As an example, the length of the susceptor is preferably selected to match the length of the rod of the aerosol-generating substrate. The width of the susceptor should preferably be selected to prevent displacement of the susceptor within the substrate, while also allowing for easy insertion during manufacturing.

[0193] The inventors have found that susceptors having thicknesses within the above-mentioned ranges are advantageous in aerosol-generating articles that are provided to inductively supply heat during use, generating and distributing heat throughout the aerosol-generating substrate in a particularly effective and efficient manner. Without wishing to be bound by theory, the inventors believe that this is because such susceptors are adapted to provide optimal heat generation and heat transfer due to the susceptor's surface area and inductive force. In contrast, thinner susceptors may be too easily deformed to maintain the desired shape and orientation within the aerosol-generating substrate rod during manufacture of the aerosol-generating article, resulting in less uniform and finely tuned heat distribution during use. At the same time, thicker susceptors may be more difficult to cut to precise and consistent lengths, which may also affect how the susceptor is accurately provided in longitudinal alignment within the aerosol-generating substrate rod, and therefore the uniformity of heat distribution within the rod. These beneficial effects are particularly noticeable when the susceptor extends all the way to the downstream end of the rod of the aerosol-generating article. This is believed to be because there is no aerosol-generating substrate within the rod downstream of the susceptor that could contribute to the resistance to draw (RTD), essentially minimizing the RTD downstream of the susceptor. This is particularly effective in embodiments in which the aerosol-generating article includes a downstream section that includes a hollow middle section. One such hollow middle section does not substantially contribute to the overall RTD of the aerosol-generating article and does not directly contact the downstream end of the susceptor.

[0194] Without wishing to be bound by theory, the inventors believe that the most downstream portion of the rod of the aerosol-generating substrate may, to some extent, act as a filter for the more upstream portions of the rod of the aerosol-generating substrate. Thus, the inventors believe that it would be desirable to be able to uniformly heat the most downstream portion of the rod of the aerosol-generating substrate as well, so that it actively participates in the release of volatile aerosol species, contributing to the overall generation and delivery of the aerosol, and that any filtering effects that may interfere with the delivery of the aerosol to the consumer are actively counteracted by the release of volatile aerosol species throughout the aerosol-generating substrate.

[0195] The elongated susceptor preferably has a length that is the same as or shorter than the length of the aerosol-generating substrate.The elongated susceptor preferably has the same length as the aerosol-generating substrate.

[0196] The susceptor may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferred susceptors include metal or carbon.

[0197] A preferred susceptor may include or consist of a ferromagnetic material (e.g., a ferromagnetic alloy, ferritic iron, or ferromagnetic steel or stainless steel). A suitable susceptor may be or include aluminum. A preferred susceptor may be formed from 400 series stainless steel, such as grade 410, or grade 420, or grade 430 stainless steel. Different materials dissipate different amounts of energy when placed in electromagnetic fields having similar values ​​of frequency and field strength.

[0198] Thus, the susceptor parameters, such as material type, length, width, and thickness, may all be modified to provide the desired power dissipation within a known electromagnetic field. Preferred susceptors may be heated to temperatures in excess of 250 degrees Celsius.

[0199] Suitable susceptors may include a non-metallic core having a metal layer disposed thereon, e.g., a metal track formed on the surface of a ceramic core. The susceptor may have a protective outer layer encapsulating the susceptor, e.g., a protective ceramic or glass layer. The susceptor may include a protective coating formed of glass, ceramic, or an inert metal formed over a core of susceptor material.

[0200] The susceptor is positioned in thermal contact with the aerosol-generating substrate. Thus, as the temperature of the susceptor increases, the aerosol-generating substrate is heated and an aerosol is formed. Preferably, the susceptor is positioned in direct physical contact with the aerosol-generating substrate, for example, within the aerosol-generating substrate.

[0201] The susceptor may be a multi-material susceptor and may include a first susceptor material and a second susceptor material. The first susceptor material is disposed in close physical contact with the second susceptor material. The second susceptor material preferably has a Curie temperature below 500 degrees Celsius. The first susceptor material is preferably primarily used to heat the susceptor when it is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum or an iron-based material such as stainless steel. The second susceptor material is preferably primarily used to indicate when the susceptor has reached a specific temperature (the Curie temperature of the second susceptor material). The Curie temperature of the second susceptor material can be used to regulate the temperature of the entire susceptor during operation. Therefore, the Curie temperature of the second susceptor material should be below the ignition point of the aerosol-generating substrate. Suitable materials for the second susceptor material may include nickel and certain nickel alloys.

[0202] By providing a susceptor having at least first and second susceptor materials with a second susceptor material having a Curie temperature and a first susceptor material without a Curie temperature, or by providing first and second susceptor materials with different first and second Curie temperatures, the heating of the aerosol-generating substrate and the temperature control of the heating can be separated. The first susceptor material is preferably a magnetic material having a Curie temperature greater than 500°C. From the standpoint of heating efficiency, it is desirable that the Curie temperature of the first susceptor material exceed any maximum temperature to which the susceptor can be heated. The second Curie temperature may be selected to be preferably lower than 400°C, preferably lower than 380°C, or even lower than 360°C. The second susceptor material is preferably a magnetic material selected to have a second Curie temperature substantially the same as the desired maximum heating temperature. That is, the second Curie temperature is preferably approximately the same as the temperature to which the susceptor must be heated to generate an aerosol from the aerosol-generating substrate. The second Curie temperature may be, for example, within the range of 200°C to 400°C, or within the range of 250°C to 360°C. The second Curie temperature of the second susceptor material may be selected, for example, so that the overall average temperature of the aerosol-generating substrate does not exceed 240°C when heated by a susceptor having a temperature equal to the second Curie temperature.

[0203] As briefly described above, in an aerosol-generating article according to the present invention, the wrapper surrounding at least the rod of aerosol-generating substrate comprises a wrapping substrate having a certain basis weight. At least a treated portion of the wrapper extending between the rod proximal end and the rod distal end comprises a flame-retardant composition including one or more flame-retardant compounds, such that the treated portion of the wrapper has a total basis weight greater than the basis weight of the wrapping substrate. In practice, the wrapper surrounding at least the rod of aerosol-generating substrate comprises a wrapping substrate, and the flame-retardant composition is applied onto the wrapping substrate, or the wrapping substrate is impregnated with the flame-retardant composition, or both. The treated portion extends over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrate.

[0204] As used herein, the term "flame retardant composition" means a composition that includes one or more flame retardant compounds.

[0205] The term "flame retardant compound" is used herein to describe a compound that, when added to or otherwise incorporated into a substrate, such as a paper or plastic compound, provides varying degrees of flammability protection to the substrate. In practice, flame retardant compounds may be activated by the presence of an ignition source and are adapted to prevent or delay the further development of ignition by a variety of different physical and chemical mechanisms.

[0206] The flame retardant composition may typically further comprise one of a number of non-flame retardant compounds, i.e., one or more compounds, such as solvents, excipients, fillers, etc., that do not actively contribute to providing flammability protection to the substrate, but that are used to facilitate application of the flame retardant compound onto and / or in the wrapper.

[0207] Some of the non-flame retardant compounds of the flame retardant composition, such as solvents, are volatile and can evaporate from the wrapper as it dries after the flame retardant composition is applied onto or into the wrapping substrate, or both. Thus, while these non-flame retardant compounds form part of the formulation of the flame retardant composition, they are no longer present, or can only be detected in trace amounts, in the wrapper of the aerosol-generating article according to the present invention.

[0208] To incorporate the flame retardant composition into a paper-based or polymer-based wrapper, the flame retardant composition may be added to the pulp or polymer mixture during the wrapper manufacturing process, or may be added to the wrapper at a later stage by an application process based on size pressing, spraying, printing, coating, etc. The flame retardant composition may be applied, for example, as a coating layer, to one side of the wrapper, or to both sides of the wrapper.

[0209] Many suitable flame retardant compounds are known. Some flame retardant compounds, such as mineral flame retardants, mainly act as additive flame retardants and do not chemically bond to the surrounding system. Most organohalogen compounds and organophosphate compounds also do not react permanently and adhere to the surroundings. Reactive flame retardant compounds, such as certain non-halogenated products, are reactive in that they can be incorporated into the surrounding system without losing their flame retardant efficiency. This advantageously prevents these materials from being released into the environment.

[0210] The wrapping substrate of the wrapper surrounding at least the rod of aerosol-generating substrate may be a paper wrapping substrate or a non-paper wrapping substrate. In a preferred embodiment, the wrapping substrate of the wrapper surrounding at least the rod of aerosol-generating substrate comprises paper. Suitable paper wrapping substrates for use in certain embodiments of the present invention are known in the art and include, but are not limited to, cigarette paper and filter plug wrap. Suitable non-paper wrapping substrates for use in certain embodiments of the present invention are known in the art and include, but are not limited to, sheets of homogenized tobacco material and sheets of certain polymeric materials. In certain embodiments, the wrapping substrate may be formed from a laminate material comprising multiple layers.

[0211] As an example, the wrapping substrate may have a basis weight of at least about 20 grams per square meter. Preferably, the wrapping substrate has a basis weight of at least about 25 grams per square meter. More preferably, the wrapping substrate has a basis weight of at least 30 grams per square meter. More preferably, the wrapping substrate has a basis weight of at least about 40 grams per square meter, or even more preferably, at least about 50 grams per square meter. In some embodiments, the wrapping substrate has a basis weight of at least about 70 grams per square meter.

[0212] The wrapping substrate may have a basis weight of up to about 220 grams per square meter. Preferably, the wrapping substrate has a basis weight of about 200 grams per square meter or less. More preferably, the wrapping substrate has a basis weight of about 180 grams per square meter or less. Even more preferably, the wrapping substrate has a basis weight of about 160 grams per square meter or less.

[0213] In a preferred embodiment, the wrapping substrate has a basis weight of about 150 grams per square meter or less, preferably about 140 grams per square meter or less, even more preferably about 130 grams per square meter or less, and most preferably about 120 grams per square meter or less.

[0214] In some embodiments, the wrapping substrate may have a basis weight of about 30 grams per square meter to about 220 grams per square meter, preferably about 40 grams per square meter to about 220 grams per square meter, more preferably about 50 grams per square meter to about 220 grams per square meter, and even more preferably about 60 grams per square meter to about 220 grams per square meter. In other embodiments, the wrapping substrate may have a basis weight of about 30 grams per square meter to about 200 grams per square meter, preferably about 40 grams per square meter to about 200 grams per square meter, more preferably about 50 grams per square meter to about 200 grams per square meter, and even more preferably about 60 grams per square meter to about 200 grams per square meter. In further embodiments, the wrapping substrate may have a basis weight of about 30 grams per square meter to about 180 grams per square meter, preferably about 40 grams per square meter to about 180 grams per square meter, more preferably about 50 grams per square meter to about 180 grams per square meter, and even more preferably about 60 grams per square meter to about 180 grams per square meter. In still other embodiments, the wrapping substrate may have a basis weight of about 30 grams per square meter to about 160 grams per square meter, preferably about 40 grams per square meter to about 160 grams per square meter, more preferably about 50 grams per square meter to about 160 grams per square meter, and even more preferably about 60 grams per square meter to about 160 grams per square meter.

[0215] In particularly preferred embodiments, the wrapping substrate may have a basis weight of from about 70 grams per square meter to about 110 grams per square meter, more preferably from about 80 grams per square meter to about 110 grams per square meter. In even more preferred embodiments, the wrapping substrate may have a basis weight of from about 70 grams per square meter to about 100 grams per square meter, and even more preferably from about 80 grams per square meter to about 100 grams per square meter.

[0216] In other embodiments, the wrapping substrate may have a basis weight of about 20 grams per square meter to about 120 grams per square meter, preferably about 25 grams per square meter to about 120 grams per square meter, more preferably about 30 grams per square meter to about 120 grams per square meter, even more preferably about 40 grams per square meter to about 120 grams per square meter, and most preferably about 50 grams per square meter to about 120 grams per square meter. In further embodiments, the wrapping substrate may have a basis weight of about 20 grams per square meter to about 100 grams per square meter, preferably about 25 grams per square meter to about 100 grams per square meter, more preferably about 30 grams per square meter to about 100 grams per square meter, even more preferably about 40 grams per square meter to about 100 grams per square meter, and most preferably about 50 grams per square meter to about 100 grams per square meter. In still further embodiments, the wrapping substrate may have a basis weight of about 20 grams per square meter to about 80 grams per square meter, preferably about 25 grams per square meter to about 80 grams per square meter, more preferably about 30 grams per square meter to about 80 grams per square meter, even more preferably about 40 grams per square meter to about 80 grams per square meter, and most preferably about 50 grams per square meter to about 80 grams per square meter. In alternative embodiments, the wrapping substrate may have a basis weight of about 20 grams per square meter to about 70 grams per square meter, preferably about 25 grams per square meter to about 70 grams per square meter, more preferably about 30 grams per square meter to about 70 grams per square meter, even more preferably about 40 grams per square meter to about 70 grams per square meter, and most preferably about 50 grams per square meter to about 70 grams per square meter.

[0217] In other embodiments, the wrapping substrate may have a basis weight of from about 20 grams per square meter to about 50 grams per square meter, preferably from about 25 grams per square meter to about 50 grams per square meter, more preferably from about 30 grams per square meter to about 50 grams per square meter, and even more preferably from about 40 grams per square meter to about 50 grams per square meter.

[0218] The wrapper surrounding at least the rod of aerosol-generating substrate has a total dry basis weight that is the sum of the basis weight of the wrapping substrate and the weight of the flame-retardant composition components present on the surface of the wrapping substrate, within the wrapping substrate, or both. The weight of the flame-retardant composition components present on or within the wrapper is the sum of the total weight of the flame-retardant compounds and the weight of any residual non-flame-retardant compounds. Within the context of the present invention, the weight of the flame-retardant composition components is also expressed in grams of component per square meter of wrapping substrate.

[0219] The ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper can be taken as an indication of the concentration of the flame retardant compounds in the wrapper.

[0220] In the aerosol-generating article according to the present invention, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper can be at least about 0.02. Preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is at least about 0.03. More preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is at least about 0.04. Even more preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is at least about 0.05.

[0221] Preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is about 0.20 or less. More preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is about 0.15 or less. Even more preferably, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper is about 0.10 or less.

[0222] In some embodiments, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper can be about 0.02 to about 0.20, preferably about 0.03 to about 0.20, more preferably about 0.04 to about 0.20, and even more preferably about 0.05 to about 0.20. In other embodiments, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper can be about 0.02 to about 0.15, preferably about 0.03 to about 0.15, more preferably about 0.04 to about 0.15, and even more preferably about 0.05 to about 0.15. In further embodiments, the ratio of the total weight of the flame retardant compounds to the total dry basis weight of the wrapper can be about 0.02 to about 0.10, preferably about 0.03 to about 0.10, more preferably about 0.04 to about 0.10, and even more preferably about 0.05 to about 0.10.

[0223] In the aerosol-generating article according to the present invention, the flame retardant composition is provided in a treated portion of the wrapper, meaning that the flame retardant composition is applied onto or in a corresponding portion of the wrapping substrate, or both. Thus, in the treated portion, the wrapper has a total dry basis weight greater than the dry basis weight of the wrapping substrate.

[0224] As briefly discussed above, most preferably, the treated portion of the wrapper extends over at least about 80 percent of the outer surface area of ​​the rod of aerosol-generating substrate. Preferably, the treated portion of the wrapper extends over at least about 85 percent of the outer surface area of ​​the rod of aerosol-generating substrate. More preferably, the treated portion of the wrapper extends over at least about 90 percent of the outer surface area of ​​the rod of aerosol-generating substrate. Even more preferably, the treated portion of the wrapper extends over at least about 95 percent of the outer surface area of ​​the rod of aerosol-generating substrate. Most preferably, the treated portion of the wrapper extends over substantially the entire outer surface area of ​​the rod of aerosol-generating substrate.

[0225] The length of the treated region may be at least about 75 percent of the length of the aerosol-generating substrate rod. Preferably, the length of the treated region is at least about 80 percent of the length of the aerosol-generating substrate rod. More preferably, the length of the treated region is at least about 85 percent of the length of the aerosol-generating substrate rod. Even more preferably, the length of the treated region is at least about 90 percent of the length of the aerosol-generating substrate rod. Most preferably, the length of the treated region is at least about 95 percent of the length of the aerosol-generating substrate rod.

[0226] In certain preferred embodiments, the length of the treated area is most preferably substantially equal to the length of the rod of the aerosol-generating substrate.

[0227] At least about 10 grams of the flame retardant composition may be applied to the treated portion per square meter of the treated portion's surface area. Preferably, at least about 12 grams of the flame retardant composition is applied to the treated portion per square meter of the treated portion's surface area. More preferably, at least about 14 grams of the flame retardant composition is applied to the treated portion per square meter of the treated portion's surface area. Even more preferably, at least about 16 grams of the flame retardant composition is applied to the treated portion per square meter of the treated portion's surface area. In particularly preferred embodiments, at least about 18 grams, or at least about 20 grams of the flame retardant composition is applied to the treated portion per square meter of the treated portion's surface area.

[0228] Preferably, about 35 grams or less of the flame retardant composition is applied onto the treated portion per square meter of the surface area of ​​the treated portion. More preferably, about 30 grams or less of the flame retardant composition is applied onto the treated portion per square meter of the surface area of ​​the treated portion. Even more preferably, about 25 grams or less of the flame retardant composition is applied onto the treated portion per square meter of the surface area of ​​the treated portion.

[0229] In some embodiments, about 10 grams to about 35 grams of the flame retardant composition is applied to the treated portion per square meter of the surface area of ​​the treated portion. Preferably, about 12 grams to about 35 grams of the flame retardant composition is applied to the treated portion per square meter of the surface area of ​​the treated portion. More preferably, about 14 grams to about 35 grams of the flame retardant composition is applied to the treated portion per square meter of the surface area of ​​the treated portion. Even more preferably, about 16 grams to about 35 grams of the flame retardant composition is applied to the treated portion per square meter of the surface area of ​​the treated portion. In particularly preferred embodiments, about 18 grams to about 35 grams, or about 20 grams to about 35 grams of the flame retardant composition is applied to the treated portion per square meter of the surface area of ​​the treated portion.

[0230] In other embodiments, about 10 grams to about 30 grams of the flame retardant composition are applied to the treated portion per square meter of the surface area of ​​the treated portion. Preferably, about 12 grams to about 30 grams of the flame retardant composition are applied to the treated portion per square meter of the surface area of ​​the treated portion. More preferably, about 14 grams to about 30 grams of the flame retardant composition are applied to the treated portion per square meter of the surface area of ​​the treated portion. Even more preferably, about 16 grams to about 30 grams of the flame retardant composition are applied to the treated portion per square meter of the surface area of ​​the treated portion. In particularly preferred embodiments, about 18 grams to about 30 grams, or about 20 grams to about 30 grams of the flame retardant composition are applied to the treated portion per square meter of the surface area of ​​the treated portion.

[0231] In further embodiments, about 10 grams to about 25 grams of the flame retardant composition are applied onto the treated portion per square meter of the surface area of ​​the treated portion. Preferably, about 12 grams to about 25 grams of the flame retardant composition are applied onto the treated portion per square meter of the surface area of ​​the treated portion. More preferably, about 14 grams to about 25 grams of the flame retardant composition are applied onto the treated portion per square meter of the surface area of ​​the treated portion. Even more preferably, about 16 grams to about 25 grams of the flame retardant composition are applied onto the treated portion per square meter of the surface area of ​​the treated portion. In particularly preferred embodiments, about 18 grams to about 25 grams, or about 20 grams to about 25 grams of the flame retardant composition are applied onto the treated portion per square meter of the surface area of ​​the treated portion.

[0232] The treated portion of the wrapper may contain at least about 0.1 grams of flame retardant composition per square meter of surface area of ​​the treated portion. Preferably, the treated portion of the wrapper contains at least about 0.5 grams of flame retardant composition per square meter of surface area of ​​the treated portion. More preferably, the treated portion of the wrapper contains at least about 1.0 grams of flame retardant composition per square meter of surface area of ​​the treated portion. Even more preferably, the treated portion of the wrapper contains at least about 2.0 grams of flame retardant composition per square meter of surface area of ​​the treated portion. In particularly preferred embodiments, the treated portion of the wrapper contains at least about 3.0 grams of flame retardant compound per square meter of surface area of ​​the treated portion, or at least about 4.0 grams of flame retardant compound per square meter of surface area of ​​the treated portion, or at least about 5.0 grams of flame retardant compound per square meter of surface area of ​​the treated portion.

[0233] Preferably, the treated portion of the wrapper contains no more than about 12 grams of flame retardant composition per square meter of surface area of ​​the treated portion. More preferably, the treated portion of the wrapper contains no more than about 10 grams of flame retardant composition per square meter of surface area of ​​the treated portion. Even more preferably, the treated portion of the wrapper contains no more than about 8 grams of flame retardant composition per square meter of surface area of ​​the treated portion.

[0234] In some embodiments, the treated portion of the wrapper comprises from about 0.5 grams to about 12 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, preferably from about 1.0 grams to about 12 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, more preferably from about 2.0 grams to about 12 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, and even more preferably from about 3.0 grams to about 12 grams of the flame retardant composition per square meter of surface area of ​​the treated portion.

[0235] In other embodiments, the treated portion of the wrapper comprises from about 0.5 grams to about 10 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, preferably from about 1.0 grams to about 10 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, more preferably from about 2.0 grams to about 10 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, and even more preferably from about 3.0 grams to about 120 grams of the flame retardant composition per square meter of surface area of ​​the treated portion.

[0236] In a further embodiment, the treated portion of the wrapper comprises from about 0.5 grams to about 8 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, preferably from about 1.0 grams to about 12 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, more preferably from about 2.0 grams to about 8 grams of the flame retardant composition per square meter of surface area of ​​the treated portion, and even more preferably from about 3.0 grams to about 8 grams of the flame retardant composition per square meter of surface area of ​​the treated portion.

[0237] In the aerosol-generating article according to the present invention, the content of the flame-retardant compound in the treated portion is preferably such that the aerosol-generating article does not ignite when heated using a resistance heating coil at 500° C. for at least 5 seconds, preferably 30 seconds. As used herein, the term "does not ignite" particularly means that combustion of the wrapper surrounding the aerosol-generating substrate does not commence and no flame is detectable.

[0238] Preferably, an aerosol-generating article according to the present invention includes a pre-ignition step using a resistive heating coil and does not ignite when submitted to the Health Canada Intense Method under a puff regime of one puff of 55 milliliters and 2 seconds duration every 30 seconds with 100 percent of the ventilation zone (if present) on the aerosol-generating article blocked. ISO 3308:2000 (Routine analytical cigarette smoking machine - definitions and standard conditions) provides further details regarding "smoking" parameters and standard test conditions.

[0239] In some embodiments, the wrapper comprises a wrapping substrate, and a layer comprising a flame-retardant compound is provided on a surface of the wrapping substrate facing the aerosol-generating substrate. In other embodiments, the wrapper comprises a wrapping substrate and a layer comprising a flame-retardant compound provided on a surface of the wrapping substrate facing away from the aerosol-generating substrate. In further embodiments, the wrapper comprises a wrapping substrate, and a flame-retardant compound or layers comprising the compound are provided on both surfaces of the wrapping substrate.

[0240] Many suitable flame retardant compounds will be known to those skilled in the art. In particular, several flame retardant compounds and formulations suitable for the treatment of cellulosic materials are known and disclosed and may find use in the manufacture of wrappers for aerosol-generating articles according to the present invention.

[0241] In some embodiments, the flame retardant composition comprises a polymer and a mixed salt based on at least one mono-, di-, and / or tricarboxylic acid, at least one polyphosphoric acid, pyrophosphoric acid, and / or phosphoric acid, and a hydroxide or salt of an alkali or alkaline earth metal, wherein the at least one mono-, di-, and / or tricarboxylic acid and the hydroxide or salt forms a carboxylate salt, and the at least one polyphosphoric acid, pyrophosphoric acid, and / or phosphoric acid and the hydroxide or salt forms a phosphate salt.

[0242] Preferably, in such embodiments, the flame retardant composition further comprises a carbonate of an alkali or alkaline earth metal.

[0243] In another embodiment, the flame retardant composition comprises at least one C 10 The cellulose may be modified with any of the above fatty acids, such as tall oil fatty acid (TOFA), phosphorylated linseed oil, and phosphorylated corn oil. Preferably, the cellulose may be modified with at least one C 10 The fatty acids are selected from the group consisting of capric acid, myristic acid, palmitic acid, and combinations thereof.

[0244] As briefly mentioned above, the aerosol-generating article of the present invention further comprises a downstream section at a location downstream of the rod of the aerosol-generating substrate. The downstream section may comprise one or more downstream elements.

[0245] According to the present invention, the downstream section of the aerosol-generating article may in particular comprise a mouthpiece element positioned downstream of and longitudinally aligned with the rod of the aerosol-generating substrate.

[0246] The mouthpiece element is preferably located at the downstream or mouth end of the aerosol-generating article and extends all the way to the mouth end of the aerosol-generating article.

[0247] Preferably, the mouthpiece element comprises at least one mouthpiece filter segment of fibrous filtration material for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filtration materials will be known to those skilled in the art. Particularly preferably, the at least one mouthpiece filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0248] In certain preferred embodiments, the mouthpiece element comprises a single mouthpiece filter segment. In alternative embodiments, the mouthpiece element comprises two or more mouthpiece filter segments axially aligned in end-to-end relationship with one another.

[0249] In certain embodiments of the present invention, the downstream section may comprise a mouth-end recess at a downstream end downstream of the mouthpiece element as described above. The mouth-end recess may be defined by a hollow tubular element provided at the downstream end of the mouthpiece. Alternatively, the mouth-end recess may be defined by an outer wrapper of the mouthpiece element, the outer wrapper extending in a downstream direction from the mouthpiece element.

[0250] The mouthpiece element may optionally include a flavorant, which may be provided in any suitable form, for example, the mouthpiece element may include one or more capsules, flavorant beads or granules, or one or more flavor-loaded threads or filaments.

[0251] In certain preferred embodiments, the downstream section of the aerosol-generating article further comprises a support element located immediately downstream of the rod of the aerosol-generating substrate, with the mouthpiece element preferably located downstream of the support element.

[0252] The support element may be formed from any suitable material or combination of materials. For example, the support element may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the support element is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibers.

[0253] The support element may comprise a first hollow tubular segment. In a preferred embodiment, the support element comprises a hollow cellulose acetate tube.

[0254] The support element is positioned substantially aligned with the rod, meaning that the length dimension of the support element is positioned approximately parallel to the longitudinal direction of the rod and article, for example, within ±10 degrees of parallel to the longitudinal direction of the rod. In a preferred embodiment, the support element extends along the longitudinal axis of the rod.

[0255] The support element preferably has an outer diameter approximately equal to the outer diameter of the rod of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0256] The peripheral wall of the support element may have a thickness of at least 1 millimeter, preferably at least about 1.5 millimeters, and more preferably at least about 2 millimeters.

[0257] The support element may have a length of from about 5 millimeters to about 15 millimeters.

[0258] Preferably, the support element has a length of at least about 6 millimeters, and more preferably at least about 7 millimeters.

[0259] In preferred embodiments, the support element has a length of less than about 12 millimeters, more preferably less than about 10 millimeters.

[0260] In some embodiments, the support element has a length of about 5 millimeters to about 15 millimeters, preferably about 6 millimeters to about 15 millimeters, and more preferably about 7 millimeters to about 15 millimeters. In other embodiments, the support element has a length of about 5 millimeters to about 12 millimeters, preferably about 6 millimeters to about 12 millimeters, and more preferably about 7 millimeters to about 12 millimeters. In further embodiments, the support element has a length of about 5 millimeters to about 10 millimeters, preferably about 6 millimeters to about 10 millimeters, and more preferably about 7 millimeters to about 10 millimeters.

[0261] In a preferred embodiment, the support element has a length of about 8 millimeters.

[0262] In some embodiments, the downstream section further comprises an aerosol cooling element located immediately downstream of the support element. The mouthpiece element is preferably located downstream of both the support element and the aerosol cooling element. Particularly preferably, the mouthpiece element is located immediately downstream of the aerosol cooling element. As an example, the mouthpiece element may abut the downstream end of the aerosol cooling element.

[0263] The aerosol cooling element is positioned substantially in alignment with the rod, meaning that the length dimension of the aerosol cooling element is positioned approximately parallel to the longitudinal direction of the rod and article, for example, within ±10 degrees of parallel to the longitudinal direction of the rod. In a preferred embodiment, the aerosol cooling element extends along the longitudinal axis of the rod.

[0264] The aerosol cooling element preferably has an outer diameter approximately equal to the outer diameter of the rod of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0265] In some embodiments, the aerosol cooling element is in the form of a hollow tubular segment defining a cavity extending entirely from the upstream end of the aerosol cooling element to the downstream end of the aerosol cooling element, with ventilation zones being provided at locations along the hollow tubular segment.

[0266] As used herein, the term "hollow tubular segment" is used generally to refer to an elongated element that defines a lumen or airflow passage along its longitudinal axis. In particular, the term "tubular" is used hereinafter with reference to a tubular element that has a substantially cylindrical cross-section and defines at least one airflow conduit that establishes uninterrupted fluid communication between the upstream end of the tubular element and the downstream end of the tubular element. However, it will be appreciated that alternative shapes (e.g., alternative cross-sectional shapes) of the tubular element may be possible.

[0267] The hollow tubular segment provides an unrestricted flow channel, meaning that it provides a negligible level of resistance to withdrawal (RTD). Therefore, the flow channel should not include any components that would obstruct longitudinal air flow. Preferably, the flow channel is substantially empty.

[0268] The term "elongated" when used to describe an aerosol cooling element means that the aerosol cooling element has a length dimension that is greater than its width dimension or its diameter dimension, for example, more than twice its width dimension or its diameter dimension.

[0269] The peripheral wall of the aerosol cooling element may have a thickness of less than about 2.5 millimeters, preferably less than about 1.5 millimeters, more preferably less than about 1250 micrometers, and even more preferably less than about 1000 micrometers. In particularly preferred embodiments, the peripheral wall of the aerosol cooling element has a thickness of less than about 900 micrometers, preferably less than about 800 micrometers.

[0270] The aerosol cooling element may have a length of between 5 millimeters and 15 millimeters.

[0271] Preferably, the aerosol cooling element has a length of at least about 6 millimeters, and more preferably at least about 7 millimeters.

[0272] In preferred embodiments, the aerosol cooling element has a length of less than about 12 millimeters, more preferably less than about 10 millimeters.

[0273] In some embodiments, the aerosol cooling element has a length of about 5 millimeters to about 15 millimeters, preferably about 6 millimeters to about 15 millimeters, and more preferably about 7 millimeters to about 15 millimeters. In other embodiments, the aerosol cooling element has a length of about 5 millimeters to about 12 millimeters, preferably about 6 millimeters to about 12 millimeters, and more preferably about 7 millimeters to about 12 millimeters. In further embodiments, the aerosol cooling element has a length of about 5 millimeters to about 10 millimeters, preferably about 6 millimeters to about 10 millimeters, and more preferably about 7 millimeters to about 10 millimeters.

[0274] In particularly preferred embodiments of the present invention, the aerosol cooling element has a length of less than 10 millimeters. For example, in one particularly preferred embodiment, the aerosol cooling element has a length of 8 millimeters. In such an embodiment, the aerosol cooling element therefore has a relatively short length compared to aerosol cooling elements of prior art aerosol-generating articles. The reduction in the length of the aerosol cooling element is possible due to optimization of the effectiveness of the hollow tubular segments forming the aerosol cooling element in aerosol cooling and nucleation. The reduction in the length of the aerosol cooling element advantageously reduces the risk of deformation of the aerosol-generating article due to compression during use, because the aerosol cooling element typically has lower resistance to deformation than the mouthpiece. Furthermore, the reduction in the length of the aerosol cooling element can provide cost benefits to manufacturers, because the cost of hollow tubular segments is typically higher per unit length than the cost of other elements, such as the mouthpiece element.

[0275] The ratio between the length of the aerosol-cooling element and the length of the rod of the aerosol-generating substrate may be from about 0.25 to about 1.

[0276] The aerosol cooling element may be formed from any suitable material or combination of materials. For example, the aerosol cooling element may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). Other suitable materials include polyhydroxyalkanoate (PHA) fibers.

[0277] In a preferred embodiment, the aerosol cooling element is formed from cellulose acetate.

[0278] The ventilation zone comprises a plurality of perforations through the peripheral wall of the aerosol cooling element. Preferably, the ventilation zone comprises at least one peripheral row of perforations. In some embodiments, the ventilation zone may comprise two peripheral rows of perforations. For example, the perforations may be formed online during manufacture of the aerosol-generating article. Preferably, each peripheral row of perforations comprises between 8 and 30 perforations.

[0279] Aerosol-generating articles according to the present invention may have a breathability level of at least about 5 percent.

[0280] The term "ventilation level" is used throughout this specification to mean the volume ratio of the airflow entering the aerosol-generating article via the ventilation zone (ventilation airflow) to the sum of the aerosol airflow and the ventilation airflow. The greater the ventilation level, the greater the dilution of the aerosol stream delivered to the consumer.

[0281] Preferably, the aerosol-generating article according to the present invention may have a ventilation level of at least about 10 percent, more preferably at least about 15 percent, and even more preferably at least about 20 percent. In a particularly preferred embodiment, the aerosol-generating article according to the present invention has a ventilation level of at least about 25 percent. Without wishing to be bound by theory, the inventors have discovered that the temperature reduction caused by admitting cooler ambient air into the hollow tubular segment through the ventilation zone can have a beneficial effect on the nucleation and growth of aerosol particles. The rapid cooling induced by admitting ambient air into the hollow tubular segment through the ventilation zone can be used to favor the nucleation and growth of aerosol droplets. However, at the same time, admitting ambient air into the hollow tubular segment has the direct disadvantage of diluting the aerosol stream delivered to the consumer. The inventors surprisingly discovered that the dilution effect on the aerosol (which can be assessed, in particular, by measuring the effect on the delivery of an aerosol former (such as glycerol) contained in the aerosol-generating substrate) is advantageously minimized when the ventilation level is within the aforementioned range.

[0282] In some embodiments, the aerosol-generating article may further comprise an additional cooling element defining multiple longitudinally extending channels, such as to make available a large surface area for heat exchange. In other words, one such additional cooling element is adapted to function substantially as a heat exchanger. The multiple longitudinally extending channels may be defined by a sheet material that has been pleated, gathered, or folded to form the channels. The multiple longitudinally extending channels may be defined by a single sheet that has been pleated, gathered, or folded to form the multiple channels. The sheet may also be crimped before being pleated, gathered, or folded. Alternatively, the multiple longitudinally extending channels may be defined by multiple sheets that have been crimped, pleated, gathered, or folded to form the multiple channels. In some embodiments, the multiple longitudinally extending channels may be defined by multiple sheets that have been crimped, pleated, gathered, or folded, i.e., two or more sheets that have been brought into an overlay arrangement and then crimped, pleated, gathered, or folded as one. As used herein, the term "sheet" means a laminar element having a width and length that is substantially greater than its thickness.

[0283] In other embodiments, the aerosol cooling element may be provided in the form of one such cooling element comprising a plurality of longitudinally extending channels.

[0284] One such additional cooling element may define and have a total surface area of ​​between about 300 square millimeters per millimeter of length and about 1000 square millimeters per millimeter of length.

[0285] The additional cooling element preferably comprises a sheet material selected from the group including metal foil, polymeric sheet, and substantially imperforate paper or cardboard. In some embodiments, the aerosol cooling element may comprise a sheet material selected from the group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), and aluminum foil. In a particularly preferred embodiment, the additional cooling element comprises a sheet of PLA.

[0286] The aerosol-generating article further comprises an upstream section located upstream of the rod of aerosol-generating substrate. The upstream section may comprise one or more upstream elements. In some embodiments, the upstream section may comprise an upstream element located immediately upstream of the rod of aerosol-generating substrate.

[0287] The aerosol-generating article of the present invention preferably includes an upstream element upstream of and adjacent to the aerosol-generating substrate, the upstream section including at least one upstream element. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-generating substrate. In particular, if the aerosol-generating substrate includes a susceptor element, the upstream element may prevent direct physical contact with the upstream end of the susceptor element. This helps to prevent displacement or deformation of the susceptor element during handling or transportation of the aerosol-generating article. This, in turn, helps to fix the shape and position of the susceptor element. Furthermore, the presence of the upstream element helps to prevent any loss of the substrate.

[0288] The upstream element may also provide an improved appearance to the upstream end of the aerosol-generating article. Additionally, if desired, the upstream element may be used to provide information about the aerosol-generating article, such as the brand, flavor, content, or details of the aerosol-generating device in which the article is intended to be used.

[0289] The upstream element may be a porous plug element. Preferably, the porous plug element does not alter the draw resistance of the aerosol-generating article. Preferably, the upstream element has a porosity of at least about 50 percent in the longitudinal direction of the aerosol-generating article. More preferably, the upstream element has a porosity of between about 50 percent and about 90 percent in the longitudinal direction. The longitudinal porosity of the upstream element is defined as the ratio of the cross-sectional area of ​​the material forming the upstream element to the internal cross-sectional area of ​​the aerosol-generating article at the location of the upstream element.

[0290] The upstream element may be made of a porous material or may comprise a plurality of openings, which may be achieved, for example, by laser drilling, and the plurality of openings are preferably homogeneously distributed across the cross section of the upstream element.

[0291] The porosity or permeability of the upstream element may be advantageously varied to provide a desired overall resistance to withdrawal of the aerosol-generating article.

[0292] Preferably, the RTD of the upstream element is at least about 5 millimeters of H2O. More preferably, the RTD of the upstream element is at least about 10 millimeters of H2O. Even more preferably, the RTD of the upstream element is at least about 15 millimeters of H2O. In a particularly preferred embodiment, the RTD of the upstream element is at least about 20 millimeters of H2O.

[0293] The RTD of the upstream element is preferably about 80 millimeters H2O or less. More preferably, the RTD of the upstream element is about 60 millimeters H2O or less. Even more preferably, the RTD of the upstream element is about 40 millimeters H2O or less.

[0294] In alternative embodiments, the upstream element may be formed from a material that is impermeable to air. In such embodiments, the aerosol-generating article may be configured to allow air to flow into the rod of aerosol-generating substrate via suitable venting means provided in the wrapper.

[0295] The upstream element may be made of any material suitable for use in an aerosol-generating article. The upstream element may be made of the same material as that used in one of the other components of the aerosol-generating article, such as the mouthpiece, cooling element, or support element. Suitable materials for the upstream element include filter material, ceramic, polymeric material, cellulose acetate, cardboard, zeolite, or an aerosol-generating substrate. The upstream element is preferably formed from a plug of cellulose acetate.

[0296] The upstream element is preferably formed from a heat resistant material, for example, a material that can withstand temperatures up to 350 degrees Celsius, to ensure that the upstream element is not adversely affected by the heating means for heating the aerosol-generating substrate.

[0297] The upstream element preferably has a diameter approximately equal to the diameter of the aerosol-generating article.

[0298] Preferably, the upstream element has a length of about 1 millimeter to about 10 millimeters, more preferably about 3 millimeters to about 8 millimeters, and even more preferably about 4 millimeters to about 6 millimeters. In a particularly preferred embodiment, the upstream element has a length of about 5 millimeters. The length of the upstream element can be advantageously varied to provide a desired overall length for the aerosol-generating article. For example, if it is desired to reduce the length of one of the other components of the aerosol-generating article, the length of the upstream element can be increased to maintain the same overall length for the article.

[0299] The upstream element is preferably surrounded by a wrapper that is preferably a stiff plug wrap, such as a plug wrap having a basis weight of at least about 80 grams per square meter (gsm), or at least about 100 gsm, or at least about 110 gsm, to provide structural rigidity to the upstream element.

[0300] Preferably, in the aerosol-generating article according to the present invention, the wrapper does not contain a metal. As used herein, the term "metal" refers to the content of metal in the zero oxidation state, i.e., the content of metal in the wrapper as an element in free form. Thus, for example, the content of metals such as alkali metals or alkaline earth metals that may be present in ionic form or that may be bound to another element in one or more flame retardant compounds of the flame retardant composition is not encompassed by the term "metal" as used herein.

[0301] In other words, the wrapper of the aerosol-generating article according to the present invention preferably does not contain metals in the zero oxidation state.

[0302] Thus, an aerosol-generating article according to the present invention advantageously does not include a metal foil acting as a heat shield element, and in particular the aerosol-generating substrate is not surrounded by one such metal foil heat shield element.

[0303] The aerosol-generating articles according to the present invention described above can be manufactured by a method including a first step of providing a continuous rod of aerosol-generating substrate. Such a method includes a second step of surrounding the continuous rod of aerosol-generating substrate with a wrapper, the wrapper including a wrapping substrate having a dry basis weight. The method further includes a third step of treating at least a portion of the wrapper with a flame-retardant composition including one or more flame-retardant compounds, so as to provide a treated portion of the wrapper having a total basis weight greater than the dry basis weight of the wrapping substrate. Furthermore, the method includes a fourth step of cutting the treated continuous rod of aerosol-generating substrate into individual rods, each extending from a proximal end of the individual rod to a distal end of the individual rod upstream of the proximal end of the individual rod. For each individual rod, the treated portion of the wrapper extends over at least about 80 percent of the outer surface area of ​​the individual rod.

[0304] The flame retardant composition may be applied to at least one side of the wrapping substrate of the wrapper by a size press, spraying, printing or coating based application process.

[0305] Aerosol-generating articles according to the present invention find particular use in aerosol-generating systems comprising an aerosol-generating article and an electrically operated aerosol-generating device, wherein the aerosol-generating device comprises a heater and an elongated heating chamber configured to receive the aerosol-generating article such that the aerosol-generating substrate of the article is heated within the heating chamber.

[0306] In some embodiments, the heater may be adapted to be inserted into the aerosol-generating substrate of the article when the article is received in the heating chamber. By way of example, the heater may be in the form of a heating rod or pin.

[0307] In other embodiments, the heater may comprise a substantially cylindrical, elongated heating element, and the heating chamber may be disposed around the circumferential longitudinal surface of the heater. As a result, during use, thermal energy supplied by the heater travels radially outward from the heater surface to the heating chamber and the aerosol-generating article. However, other shapes and configurations of the heater and heating chamber may alternatively be used. The heater may comprise multiple individual heating elements, with the various heating elements operable independently of one another so that different elements can be activated at different times to heat the aerosol-generating article. As an example, the heater may comprise multiple axially aligned heating elements providing multiple independent heating zones along the length of the heater. Each heating element may have a length significantly shorter than the overall length of the heater. Thus, when an individual heating element is activated, it supplies thermal energy to a portion of the aerosol-generating substrate radially positioned near the heating element, without substantially heating the remainder of the aerosol-generating substrate. Thus, different sections of the aerosol-generating substrate may be heated independently and at different times.

[0308] Alternatively, or in addition, the heater may comprise a plurality of elongated, longitudinally extending heating elements at different locations around the longitudinal axis of the heater. Thus, when an individual heating element is activated, it supplies thermal energy to a longitudinal portion of the aerosol-generating substrate that is positioned substantially parallel to and adjacent to the heating element. This arrangement also allows for independent heating of the aerosol-generating substrate in separate portions.

[0309] In some of these embodiments including a heater element positioned peripherally relative to the heating chamber, the aerosol generation system may further comprise insulating means positioned between the heating chamber and the exterior of the device to reduce heat loss from the heated aerosol-generating substrate.

[0310] In a further embodiment, the aerosol-generating article comprises a susceptor disposed within the aerosol-generating substrate, the susceptor being in thermal contact with the aerosol-generating substrate, and the heater being in the form of an induction heating device comprising one or more induction coils, wherein electromagnetic energy emitted by the induction coils is absorbed by the susceptor, converted to heat, and then transferred to the aerosol-generating substrate primarily by conduction.

[0311] The invention will now be further described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0312] [Figure 1] FIG. 1 shows a schematic cross-sectional side view of an aerosol-generating article according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a schematic cross-sectional side view of another aerosol-generating article according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0313] 1 comprises a rod 12 of aerosol-generating substrate 12 and a downstream section 14 located downstream of the rod 12 of aerosol-generating substrate. Additionally, the aerosol-generating article 10 comprises an upstream section 16 located upstream of the rod 12 of aerosol-generating substrate. Thus, the aerosol-generating article 10 may extend from an upstream or distal end 18 to a downstream or oral end 20.

[0314] The aerosol-generating article has a total length of about 45 millimeters.

[0315] The downstream section 14 comprises a support element 22 located immediately downstream from the rod 12 of the aerosol-generating substrate, the support element 22 being longitudinally aligned with the rod 12. In the embodiment of Figure 1, the upstream end of the support element 18 abuts the downstream end of the rod 12 of the aerosol-generating substrate. The downstream section 14 further comprises an aerosol cooling element 24 located immediately downstream from the support element 22, the aerosol cooling element 24 being longitudinally aligned with the rod 12 and the support element 22. In the embodiment of Figure 1, the upstream end of the aerosol cooling element 24 abuts the downstream end of the support element 22. In the embodiment of Figure 1, the support element 22 and the aerosol cooling element 24 together define an intermediate hollow section 50 of the aerosol-generating article 10.

[0316] The support element 22 includes a first hollow tubular segment 26. The first hollow tubular segment 26 is provided in the form of a hollow cylindrical tube made from cellulose acetate. The first hollow tubular segment 26 defines an interior cavity 28 that extends entirely from an upstream end 30 of the first hollow tubular segment to a downstream end 32 of the first hollow tubular segment 26. The interior cavity 28 is substantially empty, thus permitting substantially unrestricted airflow along the interior cavity 28.

[0317] The first hollow tubular segment 26 has a length of about 8 millimeters, an outer diameter of about 7.25 millimeters, and an inner diameter of about 1.9 millimeters. Accordingly, the peripheral wall thickness of the first hollow tubular segment 26 is about 2.67 millimeters.

[0318] The aerosol cooling element 24 includes a second hollow tubular segment 34. The second hollow tubular segment 34 is provided in the form of a hollow cylindrical tube made from cellulose acetate. The second hollow tubular segment 34 defines an interior cavity 36 that extends entirely from an upstream end 38 of the second hollow tubular segment to a downstream end 40 of the second hollow tubular segment 34. The interior cavity 36 is substantially empty, thus permitting substantially unrestricted airflow along the interior cavity 36.

[0319] The second hollow tubular segment 34 has a length of approximately 8 millimeters, an outer diameter of approximately 7.25 millimeters, and an inner diameter of approximately 3.25 millimeters. Thus, the peripheral wall thickness of the second hollow tubular segment 34 is approximately 2 millimeters. Thus, the ratio between the inner diameter of the first hollow tubular segment 26 and the inner diameter of the second hollow tubular segment 34 is approximately 0.75.

[0320] The aerosol-generating article 10 includes a ventilation zone 60 provided along the second hollow tubular segment 34. More specifically, the ventilation zone is provided approximately 2 millimeters from the upstream end of the second hollow tubular segment 34. The ventilation level of the aerosol-generating article 10 is approximately 25 percent.

[0321] 1, downstream section 14 further comprises a mouthpiece element 42 located downstream of intermediate hollow section 50. More particularly, mouthpiece element 42 is positioned immediately downstream of aerosol cooling element 24. As shown in the drawing of FIG. 1, the upstream end of mouthpiece element 42 abuts downstream end 40 of aerosol cooling element 18.

[0322] Mouthpiece element 42 is provided in the form of a cylindrical plug of low density cellulose acetate, and has a length of approximately 12 millimeters and an outer diameter of approximately 7.25 millimeters.

[0323] The rod 12 contains an aerosol-generating substrate of one of the types described above, the density of which is approximately 600 milligrams per cubic centimeter.

[0324] The aerosol-generating substrate rod 12 has an outer diameter of about 7.25 millimeters and a length of about 12 millimeters.

[0325] The aerosol-generating article 10 further includes an elongated susceptor 44 within the rod 12 of the aerosol-generating substrate. More specifically, the susceptor 44 is disposed substantially longitudinally within the aerosol-generating substrate, generally parallel to the longitudinal direction of the rod 12. As shown in the drawing of FIG. 1 , the susceptor 44 is positioned at a radially central location within the rod and effectively extends along the longitudinal axis of the rod 12. More specifically, the susceptor 44 is in thermal contact with the aerosol-generating substrate. The susceptor 44 extends completely from the upstream end to the downstream end of the rod 12. In essence, the susceptor 44 has substantially the same length as the rod 12 of the aerosol-generating substrate.

[0326] In the embodiment of FIG. 1, the susceptor 44 is provided in the form of a strip, having a length of about 12 millimeters, a thickness of about 60 micrometers, and a width of about 4 millimeters.

[0327] The upstream section 16 includes an upstream element 46 located immediately upstream of the rod 12 of the aerosol-generating substrate, and the upstream element 46 is longitudinally aligned with the rod 12. In the embodiment of Figure 1, the downstream end of the upstream element 46 abuts the upstream end of the rod 12 of the aerosol-generating substrate. This advantageously prevents the susceptor 44 from becoming dislodged. Furthermore, this prevents a consumer from accidentally contacting the heated susceptor 44 after use.

[0328] The upstream element 46 is provided in the form of a cylindrical plug of cellulose acetate surrounded by a hard wrapper. The upstream hollow element 46 has a length of approximately 5 millimeters. The RTD of the upstream element 46 is approximately 30 millimeters HO.

[0329] As shown in the drawing of Figure 1, the aerosol-generating article 10 further comprises a wrapper 70 surrounding the rod of aerosol-generating substrate 12. The wrapper 70 comprises a wrapping substrate having a basis weight of about 90 grams per square meter. Additionally, the wrapper 70 comprises a flame retardant composition comprising one or more flame retardant compounds.

[0330] More specifically, the flame-retardant composition is provided at least in a treated portion 72 of the wrapper extending between the proximal and distal ends of the aerosol-generating substrate rod 12. The treated portion 72 includes approximately 3.5 grams of one or more flame-retardant compounds per square meter of surface area of ​​the treated portion 72. Thus, the treated portion 72 of the wrapper 70 has a total basis weight greater than the basis weight of the wrapping substrate. In the embodiment of Figure 1, the treated portion 72 has a length that substantially matches the length of the aerosol-generating substrate rod 12 and extends across substantially the entire outer surface area of ​​the aerosol-generating substrate rod 12.

[0331] The aerosol-generating article 110 shown in FIG. 2 has many features in common with the aerosol-generating article 10 of FIG. 1 and, to the extent that it differs from the aerosol-generating article 10, will be described below.

[0332] 2, the aerosol-generating article 110 comprises a rod 12 of aerosol-generating substrate 12 and a modified downstream section 114 of the aerosol-generating substrate located downstream of the rod 12. Additionally, the aerosol-generating article 110 does not include an upstream section.

[0333] Similar to the downstream section 14 of the aerosol-generating article 10, the modified downstream section 114 of the aerosol-generating article 110 comprises a support element 22 positioned immediately downstream of the rod 12 of the aerosol-generating substrate, the support element 22 being longitudinally aligned with the rod 12, and the upstream end of the support element 22 abutting the downstream end of the rod 12 of the aerosol-generating substrate.

[0334] Additionally, the modified downstream section 114 includes an aerosol cooling element 124 located immediately downstream of the support element 22, the aerosol cooling element 124 being longitudinally aligned with the rod 12 and the support element 22. More specifically, the upstream end of the aerosol cooling element 124 abuts the downstream end of the support element 22.

[0335] In contrast to the downstream section 14 of the aerosol-generating article 10, the aerosol cooling element 124 of the modified downstream section 114 comprises a plurality of longitudinally extending channels that provide low or substantially null resistance to the passage of air through the rod. More specifically, the aerosol cooling element 124 is preferably formed from an imperforate sheet material selected from the group including metal foil, polymeric sheet, and substantially imperforate paper or cardboard. In particular, in the embodiment illustrated in FIG. 2, the aerosol cooling element 124 is provided in the form of a crimped sheet and sheet assembly of polylactic acid (PLA). The aerosol cooling element 124 has a length of approximately 8 millimeters and an outer diameter of approximately 7.25 millimeters.

[0336] Similar to the embodiment of Figure 1, the aerosol-generating article 110 of Figure 2 further comprises a wrapper 70 surrounding the rod of aerosol-generating substrate 12. The wrapper 70 comprises a wrapping substrate having a basis weight of about 90 grams per square meter. Additionally, the wrapper 70 comprises a flame retardant composition comprising one or more flame retardant compounds.

[0337] More specifically, the flame-retardant composition is provided at least in a treated portion 72 of the wrapper extending between the proximal and distal ends of the aerosol-generating substrate rod 12. The treated portion 72 includes approximately 3.5 grams of one or more flame-retardant compounds per square meter of surface area of ​​the treated portion 72. Thus, the treated portion 72 of the wrapper 70 has a total basis weight greater than the basis weight of the wrapping substrate. In the embodiment of Figure 1, the treated portion 72 has a length that substantially matches the length of the aerosol-generating substrate rod 12 and extends across substantially the entire outer surface area of ​​the aerosol-generating substrate rod 12.

Claims

1. 1. An aerosol-generating article for producing an inhalable aerosol upon heating, said aerosol-generating article comprising: a rod of aerosol-generating substrate extending from a proximal rod end to a distal rod end upstream of said proximal rod end; a downstream section of the aerosol-generating substrate located downstream of the rod; and a wrapper surrounding at least the rod of aerosol-generating substrate, the wrapper comprising a wrapping substrate having a basis weight; at least a treated portion of the wrapper extending between the rod proximal end and the rod distal end comprises a flame retardant composition including one or more flame retardant compounds, such that the treated portion of the wrapper has a total basis weight greater than the basis weight of the wrapping substrate; an aerosol-generating article, wherein the treated portion extends over at least about 90 percent of the outer surface area of ​​the rod of the aerosol-generating substrate;

2. 2. The aerosol-generating article of claim 1, wherein the length of the treated portion is at least about 90 percent of the length of the rod of the aerosol-generating substrate.

3. 3. An aerosol-generating article according to claim 1, wherein the treated portion extends over substantially the entire outer surface area of ​​the rod of the aerosol-generating substrate.

4. 4. The aerosol-generating article of claim 1, wherein the ratio of the total weight of the one or more flame-retardant compounds to the total basis weight of the wrapper may be at least about 0.

02.

5. 5. The aerosol-generating article of claim 1, wherein the treated portion comprises at least about 10 grams of the flame retardant composition per square meter of surface area of ​​the treated portion.

6. 6. The aerosol-generating article of claim 1, wherein the treated portion comprises no more than about 35 grams of the flame-retardant composition per square meter of surface area of ​​the treated portion.

7. 7. The aerosol-generating article of any one of claims 1 to 6, wherein the treated portion comprises at least about 0.1 grams of the one or more flame retardant compositions per square meter of surface area of ​​the treated portion.

8. 8. The aerosol-generating article of claim 1, wherein the wrapping substrate has a basis weight of at least about 20 grams per square meter.

9. 9. The aerosol-generating article according to claim 1, wherein the wrapping substrate has a basis weight of about 40 grams per square meter or less.

10. 10. The aerosol-generating article of claim 1, wherein the wrapper comprises a layer comprising one or more flame-retardant compositions provided on a surface of the wrapping substrate facing the aerosol-generating substrate, a surface of the wrapping substrate facing away from the aerosol-generating substrate, or both.

11. 11. The aerosol-generating article of claim 1, wherein the flame-retardant composition comprises a polymer and a mixed salt based on at least one mono-, di-, and / or tricarboxylic acid, at least one polyphosphoric acid, pyrophosphoric acid, and / or phosphoric acid, and a hydroxide or a salt of an alkali or alkaline earth metal, wherein the at least one mono-, di-, and / or tricarboxylic acid and the hydroxide or salt forms a carboxylate salt, and the at least one polyphosphoric acid, pyrophosphoric acid, and / or phosphoric acid and the hydroxide or salt forms a phosphate salt.

12. 12. The aerosol-generating article of claim 11, wherein the flame retardant composition further comprises a carbonate of an alkali or alkaline earth metal.

13. The flame retardant composition comprises at least one C 10 11. The aerosol-generating article according to any one of claims 1 to 10, comprising cellulose modified with the above fatty acids, tall oil fatty acid (TOFA), phosphorylated linseed oil, and phosphorylated downstream corn oil.

14. 14. The aerosol-generating article of any one of claims 1 to 13, wherein the wrapper is metal-free.

15. 15. An aerosol-generating article according to any one of claims 1 to 14, wherein the rod of aerosol-generating substrate has a length of less than about 40 millimeters and an aerosol-former content of at least about 10 percent by dry weight.

16. 16. An aerosol-generating article according to any one of claims 1 to 15, wherein the rod of aerosol-generating substrate comprises an assembly of sheets of homogenized tobacco material or a gel composition, the gel composition comprising at least one gelling agent, at least one of an alkaloid compound and a cannabinoid compound, and an aerosol former.

17. 17. An aerosol-generating article according to any one of claims 1 to 16, wherein the rod of aerosol-generating substrate further comprises a susceptor element disposed within the aerosol-generating substrate.

18. 18. An aerosol-generating article according to any one of claims 1 to 17, wherein the content of the one or more flame-retardant compounds in the treated portion is such that the aerosol-generating article does not ignite when heated using a resistive heating coil at 500 degrees Celsius for at least 5 seconds, preferably 30 seconds.

19. 1. A method of making an aerosol-generating article for producing an inhalable aerosol upon heating, said method comprising: providing a continuous rod of aerosol-generating substrate; enclosing the continuous rod of aerosol-generating substrate in a wrapper, the wrapper comprising a wrapping substrate having a dry basis weight; treating at least a portion of the wrapper with a flame retardant composition comprising one or more flame retardant compounds so as to provide the treated portion of the wrapper with a total dry basis weight greater than the dry basis weight of the wrapping substrate; cutting the treated and packaged continuous rod of aerosol-generating substrate into individual rods, each individual rod extending from an individual rod proximal end to an individual rod distal end upstream of the individual rod proximal end, such that the treated portion extends over at least about 90% of the outer surface area of ​​the individual rod.

20. 20. The method of claim 19, wherein the layer of the flame retardant composition is applied onto at least one side of the wrapping substrate by a painting process based on size pressing, spraying, printing or coating.

21. 19. An aerosol-generating system comprising an electrically operated aerosol-generating device and an aerosol-generating article according to any one of claims 1 to 18, wherein the aerosol-generating device comprises means for heating the rod of the aerosol-generating substrate to a temperature sufficient to generate an aerosol from the aerosol-generating substrate.

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