Aerosol-generating article having an aerosol-generating substrate with a double plug

Abstract

To provide a novel arrangement of an aerosol-generating substrate for an aerosol-generating article which provides greater control over the properties of the aerosol-generating substrate and the puff profile of the aerosol-generating article.SOLUTION: A heated aerosol-generating article 10 comprises a rod of an aerosol-generating substrate 12, wherein the rod of the aerosol-generating substrate 12 comprises: a first plug 26 of homogenised tobacco material; and a second plug 28 of homogenised tobacco material. The first plug 26 and the second plug 28 are coaxially aligned, the first plug 26 being provided downstream of the second plug 28, and the first plug 26 and the second plug 28 differ from each other in at least one property of the homogenised tobacco material such that upon heating of the aerosol-generating substrate 12, the first plug 26 releases aerosol after a shorter time than the second plug 28.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an aerosol-generating article comprising a rod of aerosol-generating substrate comprising dual plugs of homogenized tobacco material that differ from each other in at least one characteristic, and a method for making such a rod of aerosol-generating substrate. [Background technology]

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

[0003] Numerous prior art documents disclose aerosol generating devices for consuming or smoking heated aerosol-generating articles. Such devices include, for example, electrically heated aerosol generating devices in which the aerosol is generated by heat transfer from one or more electric heating elements of the aerosol generating device to the aerosol-generating substrate of the heated aerosol-generating article. One advantage of such electrically heated aerosol generating devices is that they significantly reduce sidestream smoke.

[0004] Substrates for heated aerosol-generating articles have typically been produced using randomly oriented pieces, strands, or strips of tobacco material. It is also known to manufacture substrates for heated aerosol-generating articles from homogenized tobacco material sheets. For example, International Patent Application No. WO-A-2012 / 164009 discloses a rod for heated aerosol-generating articles formed from an assembly of homogenized tobacco material sheets. The rod disclosed in WO-A-2012 / 164009 has longitudinal porosity that allows air to be drawn through the rod. In effect, the folds in the assembly of tobacco material sheets define longitudinal channels through the rod.

[0005] It would be desirable to provide new arrangements of aerosol-generating substrates for aerosol-generating articles that offer better control over the properties of the aerosol-generating substrate and the smoke draw profile of the aerosol-generating article. It would be particularly desirable to provide such aerosol-generating substrates that provide more consistent and improved aerosol delivery over time. It would also be desirable to provide such aerosol-generating substrates that can be manufactured efficiently and rapidly.

[0006] According to a first aspect of the present invention, there is provided a heated aerosol-generating article comprising a rod of aerosol-generating substrate, the rod of aerosol-generating substrate comprising a first plug of homogenized tobacco material and a second plug of homogenized tobacco material, the first plug and the second plug being coaxially aligned, the first plug being provided downstream of the second plug, and the first plug and the second plug differing from each other in at least one property of the homogenized tobacco material such that upon heating of the aerosol-generating substrate, the first plug releases an aerosol after a shorter time than the second plug.

[0007] According to a second aspect of the present invention, there is provided an aerosol-generating system comprising an aerosol-generating article as defined above in relation to the first aspect of the present invention, and an aerosol-generating device adapted to receive the aerosol-generating article, the aerosol-generating device comprising a heater element configured to heat both the first and second plugs of homogenized tobacco material during use, such that upon heating of the aerosol-generating substrate by the heater element, the first plug releases an aerosol more quickly than the second plug of homogenized tobacco material.

[0008] According to a third aspect of the present invention, there is provided a method of at least partially making a rod of aerosol-generating substrate for an aerosol-generating article as defined in the preceding claims, the method comprising the steps of: providing a first plug of homogenized tobacco material; providing a second plug of homogenized tobacco material, the first plug differing from the second plug in at least one property of the homogenized tobacco material such that the first plug releases an aerosol in a shorter time than the second plug upon heating of the aerosol-generating substrate; combining the first plug and the second plug so that they are coaxially aligned and the first plug is disposed downstream of the second plug; and packaging the combined first and second plugs to form the rod of aerosol-generating substrate.

[0009] According to a fourth aspect of the present invention, there is provided a rod for use as an aerosol-generating substrate in an aerosol-generating article, the rod comprising a first plug of homogenized tobacco material and a second plug of homogenized tobacco material downstream of the first plug of aerosol-generating material, the first plug and the second plug being coaxially aligned, the first plug being provided downstream of the second plug, and the first plug and the second plug differ from each other in at least one property of the homogenized tobacco material such that, during use, upon heating of the rod, the first plug releases an aerosol after a shorter time than the second plug.

[0010] Any reference below to preferred features or aspects of the rod of the aerosol-generating substrate of the aerosol-generating article according to the invention should be considered as applicable to all aspects of the invention.

[0011] As used herein, the term "heated aerosol-generating article" refers to an aerosol-generating article for aerosol production that includes an aerosol-generating substrate that is intended to be heated, rather than combusted, to release volatile compounds capable of forming an aerosol.

[0012] As used herein, the term "aerosol-generating substrate" refers to a substrate capable of releasing, upon heating, volatile compounds capable of forming an aerosol. The aerosol generated from the aerosol-generating substrate of the aerosol-generating articles described herein may be visible or invisible and may include vapor (e.g., fine particles of a substance in a gaseous state that is normally a liquid or solid at room temperature) and liquid droplets of the gas and condensed vapor.

[0013] As used herein, the term "rod" refers to a generally cylindrical element of substantially polygonal cross-section, and preferably circular, oval, or elliptical. As used herein, the term "plug" refers to a separate, individual element of homogenized tobacco material that forms a component of the rod. As used herein, the term "sheet" refers to a layered element having a width and length that is substantially greater than its thickness. As used herein, the term "web" refers to a layered material having a length that is substantially greater than its width. Typically, as used herein, the term "web" refers to a continuous layer of material from which a sheet is formed.

[0014] As used herein, the term "homogenized tobacco material" encompasses any tobacco material formed by agglomeration of particles of tobacco material. A sheet or web of homogenized tobacco material is formed by agglomerating particulate tobacco obtained by grinding or otherwise pulverizing one or both of tobacco lamina and tobacco stems. Additionally, homogenized tobacco material may contain one or more small amounts of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. A sheet of homogenized tobacco material may be produced by casting, extrusion, a papermaking process, or any other suitable process known in the art.

[0015] As used herein, the terms "upstream" and "downstream" describe the relative position of an element (or part of an element) of an aerosol-generating article with respect to the direction in which aerosol is transported through the aerosol-generating article during use.

[0016] In the following, the terms "fast-release" and "sustained-release" are used to distinguish between the first and second plugs, respectively, that form the rod of the aerosol-generating substrate, and to indicate how quickly aerosol is released from each plug upon heating compared to other plugs when the plugs are heated under the same conditions in the same apparatus. Summary of the Invention

[0017] As described above, the aerosol-generating article of the present invention incorporates a rod comprising a first plug (hereinafter also referred to as a "rapid-release plug") and a second plug (hereinafter also referred to as a "slow-release plug") that are adapted to differ in at least one characteristic such that, upon heating, the rapid-release plug begins to release a measurable amount of aerosol in a shorter time than the slow-release plug. The use of these two different plugs provides greater control over the overall rod characteristics. By providing the rapid-release plug downstream of the slow-release plug, arranging these two plugs in coaxial alignment, and tailoring the plugs to have at least one mutually different characteristic, the smoking experience provided by the rod can be more precisely tuned and controlled to vary the aerosol release profile from the rod. This effect can advantageously be achieved by heating both plugs using a single heater element, eliminating the need to adapt the device for heating the aerosol-generating article.

[0018] As a result of their different properties, the rapid-release plug and the sustained-release plug exhibit different aerosol release profiles, or puff profiles, which correspond to the amount of aerosol released from the plug during each puff over the consumption period. In the arrangement of the present invention, the rapid-release plug releases aerosol within a shorter time period after the onset of heating of the rod than the sustained-release plug. This is because the rapid-release plug typically has a lower activation temperature than the sustained-release plug, where the activation temperature corresponds to the minimum temperature at which a measurable amount of aerosol is released from the plug. Thus, the rapid-release plug's lower activation temperature shortens the time to the consumer's first puff, and the rapid-release plug releases a higher amount of aerosol during the beginning of the puff profile than the sustained-release plug.

[0019] On the other hand, the sustained-release plug takes longer to begin releasing aerosol after heating, but continues to release aerosol after the aerosol release from the quick-release plug has ended. Thus, the sustained-release plug releases a higher amount of aerosol during puffs toward the end of the puff profile than the quick-release plug. Thus, in combination, the quick-release plug and the sustained-release plug can provide highly consistent aerosol delivery over time during consumption of the aerosol-generating article.

[0020] Providing a double plug within a rod of aerosol-generating substrate does not affect the overall structure of the rod or the aerosol-generating article, and therefore a rod of aerosol-generating substrate comprising a double plug of homogenized tobacco material can advantageously be incorporated into existing high-speed production lines for the manufacture of heated smoking articles without requiring significant modifications of equipment or technology.

[0021] The aerosol-generating article according to the present invention is suitable for use in an aerosol-generating system comprising an electrically heated aerosol generator having an internal heater element for heating the aerosol-generating substrate. For example, the aerosol-generating article according to the present invention finds particular application in an aerosol-generating system comprising an electrically heated aerosol generator having an internal heater blade adapted to be inserted into the rod of the aerosol-generating substrate. Aerosol-generating articles of this type are described in the prior art, for example, in EP-A-0 822 670. Alternatively, the aerosol-generating article according to the present invention may find application in an aerosol-generating system comprising an external heater element that surrounds and heats the rod of the aerosol-generating substrate from the outside.

[0022] Preferably, the rod of the aerosol-generating substrate is adapted so that both the rapid-release plug and the sustained-release plug can be heated by the same heater element of the aerosol-generating device. This advantageously allows a rod with dual plugs to be heated in an existing aerosol-generating device without requiring modification of the heater element. However, it will be appreciated that in alternative embodiments, the aerosol-generating device can be adapted to provide a different heater element for each plug, allowing different heating profiles to be provided for each plug.

[0023] 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.

[0024] Alternatively, the aerosol-generating article according to the invention may be provided with a combustible carbon heat source for heating the aerosol-generating substrate during use. Aerosol-generating articles of this type are described in the prior art, for example in International Patent Application No. WO-A-2009 / 022232.

[0025] In the rod of aerosol-generating substrate of the aerosol-generating article according to the present invention, the immediate-release plug and the sustained-release plug are disposed coaxially relative to one another. Preferably, the immediate-release plug and the sustained-release plug are disposed in an adjacent end-to-end relationship. Alternatively, the immediate-release plug and the sustained-release plug may be longitudinally spaced apart from one another.

[0026] As briefly mentioned above, the first or rapid-release plug is downstream of the second or sustained-release plug. In such an arrangement, the rapid-release plug is provided closer to the mouth end of the aerosol-generating article so that the aerosol has to travel a shorter distance to reach the consumer. This can help further reduce the time it takes for the aerosol to be released after heating of the rod is initiated. Furthermore, this can reduce the risk of aerosol deposition from the rapid-release plug on subsequent downstream plugs, which can adversely affect aerosol delivery at the beginning of the puff profile. In an alternative embodiment, it may be preferable to provide the rapid-release plug upstream of the sustained-release plug.

[0027] As described above, the immediate-release plug and the sustained-release plug are adapted to differ in at least one property of the homogenized tobacco material to provide different release profiles from the plug. The immediate-release plug and the sustained-release plug may differ in the properties of the homogenized tobacco material forming the plug. Alternatively, or in addition, the immediate-release plug and the sustained-release plug may differ in the properties of the entire plug, which may be determined, for example, by the shape or arrangement of the homogenized tobacco material within the plug.

[0028] According to a first preferred embodiment of the present invention, the immediate-release plug and the sustained-release plug are adapted so that the sustained-release plug has a higher density than the immediate-release plug, which means that the sustained-release plug is provided with a higher amount of homogenized tobacco material per unit volume than the immediate-release plug.

[0029] The sustained-release plug having a higher density is preferably provided upstream of the rapid-release plug. Thus, the sustained-release plug can be provided at the upstream end of the rod of the aerosol-generating substrate. This arrangement provides the advantage, as described above, that the rapid-release plug is located near the mouth end of the aerosol-generating article. Additionally, if the aerosol-generating article is intended for use in an aerosol-generating device that includes a heater blade for insertion into the rod, positioning the higher-density plug at the upstream end of the rod advantageously allows for a more snug fit with the heater blade. Furthermore, this reduces the risk of tobacco being pulled from the rod by the heater blade when the aerosol-generating article is removed from the device, thereby reducing the need for cleaning the device.

[0030] Preferably, the density of the sustained release plug is at least about 10 percent higher than the density of the immediate release plug, more preferably at least about 15 percent higher, and even more preferably at least about 20 percent higher.

[0031] The density of the sustained release plug is preferably at least about 0.1 mg / cubic millimeter higher than the density of the immediate release plug, more preferably at least about 0.15 mg / cubic millimeter higher, and even more preferably at least about 0.2 mg / cubic millimeter higher.

[0032] The density of the sustained-release plug is preferably about 0.65 mg / cubic millimeter to about 0.85 mg / cubic millimeter, and more preferably about 0.7 mg / cubic millimeter to about 0.8 mg / cubic millimeter. The selection of the density of the sustained-release plug from within these ranges should be such that the desired difference in density between the immediate-release plug and the sustained-release plug, as defined above, is maintained.

[0033] The density of the immediate-release plug is preferably about 0.45 mg / cubic millimeter to about 0.65 mg / cubic millimeter, and more preferably about 0.5 mg / cubic millimeter to about 0.6 mg / cubic millimeter. Selection of the density of the immediate-release plug from within these ranges should be such that the desired difference in density between the immediate-release plug and the sustained-release plug, as defined above, is maintained.

[0034] The density of each plug can be easily adjusted by one skilled in the art to provide the necessary variation between plugs. For example, the density of the homogenized tobacco material forming the plugs may vary from plug to plug. Alternatively, or additionally, the arrangement of the homogenized tobacco material within the plugs may vary from plug to plug, such that the percentage of free space within the plug may vary from plug to plug.

[0035] Preferably, the sustained release plug has a higher resistance to withdrawal than the immediate release plug.

[0036] According to a second preferred embodiment of the present invention, the immediate-release plug and the sustained-release plug are adapted so that the homogenized tobacco material has a different aerosol-former composition for each plug. As used herein, the term "aerosol former" describes any suitable known compound or mixture of compounds that facilitates the formation of an aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the aerosol-generating article. Different aerosol formers provide different rates of aerosol release, so the type of aerosol former or the amount of a particular aerosol former (or both) can be adjusted for each plug to provide the required immediate-release and sustained-release profiles.

[0037] Both the sustained-release plug and the immediate-release plug preferably contain glycerol as an aerosol former, with the sustained-release plug having a higher amount of glycerol as an aerosol former than the immediate-release plug. The sustained-release plug preferably has at least about 2 weight percent more glycerol than the immediate-release plug, more preferably at least about 5 weight percent more, and even more preferably at least about 8 weight percent more.

[0038] In those embodiments in which the sustained-release plug contains a higher amount of glycerol, it is preferred that at least the immediate-release plug further contain propylene glycol as an aerosol former. It is particularly preferred that the immediate-release plug have at least about 2 weight percent more propylene glycol than the sustained-release plug. The sustained-release plug may contain a percentage of propylene glycol in addition to glycerol, or may be substantially free of propylene glycol.

[0039] Preferably, sustained-release plugs contain greater than about 15 weight percent glycerol in combination with about 4 weight percent or less propylene glycol, and immediate-release plugs contain about 15 weight percent or less glycerol in combination with at least about 5 weight percent propylene glycol. The selection of the amounts of glycerol and propylene glycol from within these ranges for each plug should maintain the preferred difference in the amounts of glycerol and propylene glycol between immediate-release and sustained-release plugs, as defined above.

[0040] Preferably, the sustained-release plug contains about 17 to about 25 weight percent glycerol in combination with about 0 to about 4 weight percent propylene glycol, and the immediate-release plug contains about 5 to about 15 weight percent glycerol in combination with about 5 to about 15 weight percent propylene glycol. More preferably, the sustained-release plug contains about 18 to about 22 weight percent glycerol in combination with about 0 to about 2 weight percent propylene glycol, and the immediate-release plug contains about 8 to about 12 weight percent glycerol in combination with about 8 to about 12 weight percent propylene glycol. The selection of the amounts of glycerol and propylene glycol within these ranges for each plug should maintain the preferred difference in the amounts of glycerol and propylene glycol between the immediate-release plug and the sustained-release plug, as defined above.

[0041] Propylene glycol as an aerosol former has been found to provide a faster aerosol release than glycerol, so to control the release profile, the composition of the aerosol former in each plug was tailored so that the sustained release plugs had higher amounts of glycerol, while the fast release plugs had higher amounts of propylene glycol.

[0042] The total aerosol former content of each plug is preferably about 15 to about 25 weight percent, more preferably about 18 to about 22 weight percent. The sustained-release plug and the immediate-release plug preferably have substantially the same total aerosol former content, with the difference between the plugs being the ratio of glycerol to propylene glycol in the aerosol former.

[0043] According to a third embodiment of the present invention, the immediate-release plug and the sustained-release plug are adapted such that the sustained-release plug has a higher density than the immediate-release plug, as described above in connection with the first embodiment of the present invention, and the sustained-release plug and the immediate-release plug have different aerosol former compositions, as described above in connection with the second embodiment of the present invention.

[0044] As described above, each plug in the rod of aerosol-generating substrate is formed from homogenized tobacco material. The homogenized tobacco material in each plug can take a variety of forms. Preferably, at least one of the immediate-release plug and the sustained-release plug is formed from one or more sheets of homogenized tobacco material. Preferably, at least one of the immediate-release plug and the sustained-release plug is formed from one or more sheets of homogenized tobacco material that are gathered to form the plug.

[0045] One or more sheets of homogenized tobacco material may advantageously be 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 in addition to being crimped, one or more sheets of homogenized tobacco material may be embossed, debossed, perforated, or otherwise modified to provide texture to one or both sides of the sheet.

[0046] The sheets of homogenized tobacco material used in the rods of aerosol-generating articles according to the present invention preferably comprise particulate tobacco obtained by grinding or otherwise comminuted tobacco lamina. When multiple sheets are provided in one of the plugs, the sheets may all have substantially the same composition as one another. Alternatively, the multiple sheets may comprise sheets of at least two different compositions.

[0047] The sheets of homogenized tobacco material used in 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.

[0048] The sheets of homogenized tobacco material used in the present invention may include one or more intrinsic binders that are tobacco intrinsic binders, one or more extrinsic binders that are tobacco extrinsic binders, or a combination thereof, to aid in the aggregation of the particulate tobacco. Alternatively, or in addition, the sheets of homogenized tobacco material used in the aerosol-generating substrate may include other additives, including, but not limited to, tobacco and non-tobacco fibers, aerosol-forming agents, humectants, plasticizers, flavorants, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0049] Suitable extrinsic binders for inclusion in the sheets of homogenized tobacco material used in the present invention are well known in the art and include, but are not limited to, gums such as guar gum, xanthan gum, gum arabic, locust bean gum, and the like; cellulosic binders such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, and the like; polysaccharides such as starch, organic acids (e.g., alginic acid), conjugate base salts of organic acids (e.g., sodium alginate), agar, pectin, and the like; and combinations thereof.

[0050] Suitable non-tobacco fibers for inclusion in sheets of homogenized tobacco material for use in aerosol-generating substrates are well known in the art and include, but are not limited to, cellulose fibers, soft wood fibers, hard wood fibers, jute fibers, and combinations thereof. Prior to inclusion in sheets of homogenized tobacco material for use in aerosol-generating substrates, the non-tobacco fibers may be processed by any suitable process known in the art, including, but not limited to, mechanical pulping, refining, chemical pulping, bleaching, sulfate pulping, and combinations thereof.

[0051] Preferably, the sheet of homogenized tobacco material includes an aerosol former. The sheet of homogenized tobacco material may include a single aerosol former. Alternatively, the sheet of homogenized tobacco material may include a combination of two or more aerosol formers.

[0052] Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as propylene glycol, triethylene glycol, 1,3-butanediol, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.).

[0053] Preferably, the sheet of homogenized tobacco material has an aerosol former content of greater than 5 percent on a dry weight basis.

[0054] The homogenized tobacco material sheet may have an aerosol former content of from about 5 percent to about 30 percent on a dry weight basis.

[0055] In one preferred embodiment, the homogenized tobacco material sheet has an aerosol former content of approximately 20 percent on a dry weight basis.

[0056] As noted above, in the rods of aerosol-generating substrates of the aerosol-generating articles according to the second and third preferred embodiments of the present invention, the aerosol former in each plug comprises glycerol or a combination of glycerol and propylene glycol, with the ratio of glycerol to propylene glycol adjusted to provide the desired aerosol release profile for each plug.

[0057] The homogenized tobacco sheet used in the present invention preferably has a width of about 70 mm to about 250 mm, for example, about 120 mm to about 160 mm. The thickness of the homogenized tobacco material sheet is preferably about 50 micrometers to 300 micrometers, and more preferably about 150 micrometers to about 250 micrometers.

[0058] The homogenized tobacco sheets used in the aerosol-generating articles of the present invention may be made by methods well known in the art (for example, the method disclosed in International Patent Application No. WO-A-2012 / 164009 A2).

[0059] In one preferred embodiment, a homogenized sheet of tobacco material for use in an aerosol-generating article is formed by a casting process from a slurry containing particulate tobacco, guar gum, cellulose fibers, and glycerin.

[0060] In a preferred embodiment of the present invention, both the immediate-release plug and the second release plug are formed from one or more sheets of homogenized tobacco material, with the composition or arrangement of the sheets in each plug being adapted to provide a desired difference in aerosol release profile, as described above. Alternatively, one of the plugs may be formed from one or more sheets of homogenized tobacco material, while the other plug may be in a different form. For example, the other plug may be formed from extruded tobacco material or multiple longitudinal strands of tobacco material. Alternatively, both plugs may be formed from tobacco material that is not in sheet form (such as those described above).

[0061] The immediate-release plug and the sustained-release plug preferably have substantially the same length, but in some embodiments, they may have different lengths. The preferred length of each plug is about 3 mm to about 8 mm, and more preferably about 4 mm to about 6 mm. The rod of the aerosol-generating substrate comprising the double plug may have a length of about 7 mm to about 15 mm. In one embodiment, the rod of the aerosol-generating substrate may have a length of about 10 mm. In one preferred embodiment, the rod of the aerosol-generating substrate has a length of about 12 mm.

[0062] The rod of the aerosol-generating substrate preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

[0063] The aerosol-generating substrate rod preferably has an outer diameter of at least 5 millimeters. The aerosol-generating substrate rod may have an outer diameter of about 5 millimeters to about 12 millimeters, for example, about 5 millimeters to about 10 millimeters, or about 6 millimeters to about 8 millimeters. In one preferred embodiment, the aerosol-generating substrate rod has an outer diameter of 7.2 millimeters ±10 percent.

[0064] 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.

[0065] The rod of aerosol-generating substrate is preferably surrounded by a wrapper, which secures the plug of homogenized tobacco material together. The wrapper may be formed of a porous or non-porous sheet material. The wrapper may be formed of any suitable material or combination of materials. Preferably, the wrapper is a paper wrapper. The immediate-release plug and the sustained-release plug may optionally be wrapped individually before being packaged together as described above.

[0066] Aerosol-generating articles according to the present invention preferably comprise a rod of aerosol-generating substrate consisting solely of immediate-release and sustained-release plugs, although in alternative embodiments, additional plugs of homogenized tobacco material may be combined with the immediate-release and sustained-release plugs.

[0067] Aerosol-generating articles according to the present invention preferably comprise one or more elements in addition to the rod of aerosol-generating substrate, with the rod and one or more elements assembled within a substrate wrapper. For example, aerosol-generating articles according to the present invention may further comprise at least one of a mouthpiece, an aerosol-cooling element, and a support element such as a hollow acetate tube. For example, in one preferred embodiment, the aerosol-generating article comprises, in a linear, continuous arrangement, a rod of aerosol-generating substrate as described above, a support element located immediately downstream of the aerosol-forming substrate, an aerosol-cooling element located downstream of the support element, and an outer wrapper surrounding the rod, support element, and aerosol-cooling element.

[0068] An aerosol-generating system according to a second aspect of the present invention comprises an aerosol-generating article as described above in combination with an aerosol-generating device adapted to receive the aerosol-generating article and comprising a heating element configured to heat both the immediate-release plug and the sustained-release plug of homogenized tobacco material during use.

[0069] The heater element is preferably a heater blade adapted to be inserted into the rod of the aerosol-generating substrate so that the heater blade heats both the plug and the homogenized tobacco material from the inside. Alternatively, the heater element may be an external heater that at least partially surrounds the plug of homogenized tobacco material and heats both of them from the outside. An external heater element typically heats the plug of homogenized tobacco material through at least one wrapper surrounding the rod, which may or may not be in contact with the surface of the rod. In some devices, an induction heater element may be provided.

[0070] The heater element may provide a uniform heating profile along its length. Alternatively, the heater element may be configured to provide different heating profiles along its length, and the immediate-release plug and the sustained-release plug may be heated with different heating profiles. In this manner, the heating profile for each plug can be tailored separately to take into account the structure of the plug.

[0071] A rod of aerosol-generating substrate for use in an aerosol-generating article according to the present invention, as described in detail above, can be manufactured using the method according to the third aspect of the present invention, as defined above. In a first step of the method according to the present invention, an immediate-release plug of homogenized tobacco material and a sustained-release plug of homogenized tobacco material are provided, the immediate-release plug and the sustained-release plug differing in at least one property to provide different aerosol release profiles, as described above. The immediate-release plug and the sustained-release plug are combined such that the plugs are coaxially aligned and the combined plugs are packaged to form a rod.

[0072] The wrapped rod can then be combined with the other components of the aerosol-generating article using conventional assembly methods.

[0073] Preferably, a continuous alternating arrangement of immediate-release plugs and sustained-release plugs is provided, which is packaged to form a continuous rod. The continuous rod is then cut to form a plurality of individual rods. In some embodiments of the present invention, each individual rod comprises an arrangement of immediate-release plugs and sustained-release plugs to form a pair of aerosol-generating articles. In such an arrangement, the plug intended to be downstream is provided between the pair of upstream plugs, with the downstream plug having a length twice the length of the downstream plug in the assembled aerosol-generating article. Once the pair of aerosol-generating articles is assembled, the arrangement of plugs can be cut in the middle to form two separate aerosol-generating articles, each comprising a rod with a double plug.

[0074] The invention will now be further described with reference to the figures. [Brief explanation of the drawings]

[0075] [Figure 1] FIG. 1 shows a schematic longitudinal cross-section of an aerosol-generating article according to the present invention. [Figure 2] FIG. 2 shows an exploded view of a first embodiment of a rod of aerosol-generating substrate for use in the aerosol-generating article shown in FIG. [Figure 3] FIG. 3 shows an exploded view of a second embodiment of a rod of aerosol-generating substrate for use in the aerosol-generating article shown in FIG. [Figure 4] FIG. 4 shows a longitudinal cross-sectional view of an aerosol generating system comprising an electrically operated aerosol generating device and an aerosol-generating article as shown in FIG. 1 or 2. DETAILED DESCRIPTION OF THE INVENTION

[0076] The aerosol-generating article 10 shown in Figure 1 comprises a rod of aerosol-generating substrate 12, a hollow cellulose acetate tube 14, a spacer element 16, and a mouthpiece filter 18. These four elements are arranged in continuous, coaxial alignment and surrounded by a substrate wrapper 20 to form the aerosol-generating article 10. The aerosol-generating article 10 has a mouth end 22 and a distal end 24 located at the opposite end of the article from the mouth end 22. The aerosol-generating article 10 shown in Figure 1 is particularly suitable for use in an electrically operated aerosol generating device that includes a heater for heating the rod of aerosol-generating substrate.

[0077] The rod of aerosol-generating substrate 12 has a length of about 12 millimeters and a diameter of about 7 millimeters. The rod 12 is cylindrical in shape and has a substantially circular cross section.

[0078] A first embodiment of a rod of aerosol-generating substrate 12 for use in the aerosol-generating article 10 of Figure 1 is shown in Figure 2. The rod 12 comprises a double plug of homogenized tobacco material, an immediate-release plug 26 provided at the downstream end of the rod 12, and a sustained-release plug 28 provided at the upstream end of the rod 12. The immediate-release plug 26 and the sustained-release plug 28 are of substantially equal length to each other and are provided in adjacent end-to-end relationship in the assembled aerosol-generating article 10.

[0079] Each of the immediate-release plug 26 and the sustained-release plug 28 is formed from an assembly of a sheet of homogenized tobacco material. The sheet of homogenized tobacco material forming the sustained-release plug 28 is assembled such that the sustained-release plug 28 has a density that is at least 30 percent greater than the density of the immediate-release plug 26.

[0080] A second embodiment of a rod of aerosol-generating substrate 112 for use in the aerosol-generating article 10 of Figure 1 is shown in Figure 3. Similar to the rod of aerosol-generating substrate 12 shown in Figure 2, the rod 112 includes an immediate-release plug 126 provided at the downstream end of the rod 112 and a sustained-release plug 128 provided at the upstream end of the rod 112. The immediate-release plug 126 and the sustained-release plug 128 have substantially equal lengths and are provided in adjacent end-to-end relationship in the assembled aerosol-generating article 10.

[0081] Each of the immediate-release plug 126 and the sustained-release plug 128 is formed from an assembly of sheets of homogenized tobacco material, and the plugs have substantially the same density as each other. However, the sheets forming the immediate-release plug 126 and the sustained-release plug 128 have different compositions. In particular, the homogenized tobacco material of the immediate-release plug 126 has a different aerosol former composition than the homogenized tobacco material of the sustained-release plug 128. The aerosol former of the homogenized tobacco material of the immediate-release plug 126 includes a combination of glycerol and propylene glycol in a 1:1 ratio. The aerosol former of the homogenized tobacco material of the sustained-release plug 128 includes glycerol without propylene glycol. In each of the plugs, the total aerosol former content of the homogenized tobacco material is approximately 20 weight percent.

[0082] Figure 4 shows a portion of an electrically operated aerosol generating system 200 that utilizes a heater blade 210 to heat the rod of the aerosol-generating substrate 12 of the aerosol-generating article 10 shown in Figure 1. The heater blade 210 is mounted within an aerosol-generating article chamber within the housing of an electrically operated aerosol-generating device 212. The aerosol-generating device 212 defines a plurality of air holes 214, as shown by the arrows in Figure 4, for allowing air to flow through the aerosol-generating article 10. The aerosol-generating device 212 includes a power source and electronic components, which are not shown in Figure 6.

[0083] The aerosol-generating article 10 shown in Figure 1 is designed to be engaged with an aerosol-generating device 212 shown in Figure 4 for consumption. A user inserts the aerosol-generating article 10 into the aerosol-generating device 212 so that the heater blade 210 is inserted through both the immediate-release plug 26 and the sustained-release plug 28 and into the rod of the aerosol-generating substrate 12. The mouthpiece filter 18 protrudes outward from the oral end of the device 212. After the aerosol-generating article 10 engages the aerosol-generating device 212, the dual plugs 26, 28 of the rod of the aerosol-generating substrate 12 are both simultaneously heated by the heater blade 210 to a temperature sufficient to generate an aerosol from the rod of the aerosol-generating substrate 12. The aerosol is drawn through the oral-end filter 18.

[0084] When the rod of aerosol-generating substrate 12 is heated during use, immediate-release plug 28 begins to release aerosol within a shorter time after heating begins than sustained-release plug 26. Therefore, immediate-release plug 28 has a lower activation temperature. As the temperature increases further, sustained-release plug 28 will also release aerosol.

[0085] It will be appreciated that an aerosol-generating article 10 incorporating the rod of aerosol-generating substrate 112 shown in Figure 3 may be consumed in a similar manner using the aerosol-generating device 212 shown in Figure 4. As described in relation to the rod of aerosol-generating substrate 12, when the rod of aerosol-generating substrate 52 is heated during use, the immediate-release plug 128 begins to release aerosol within a shorter time than the sustained-release plug 126 after heating begins.

[0086] Of course, the aerosol-generating article 10 shown in FIG. 1 may also be suitable for use in other types of aerosol-generating devices.

[0087] 1. A heated aerosol-generating article comprising a rod of aerosol-generating substrate, said rod of aerosol-generating substrate comprising: a first plug of homogenized tobacco material; and a second plug of homogenized tobacco material, wherein the first plug and the second plug are coaxially aligned, the first plug is provided downstream of the second plug, and the first plug and the second plug differ from each other in at least one property of the homogenized tobacco material such that upon heating of the aerosol-generating substrate, the first plug releases an aerosol after a shorter time than the second plug. 2. The heated aerosol-generating article described in 1, wherein the second plug has a higher density than the first plug. 3. The heated aerosol-generating article described in 2, wherein the density of the second plug is at least 10 percent higher than the density of the first plug, and more preferably 20 percent higher. 4. A heated aerosol-generating article according to 2 or 3, wherein the density of the second plug is at least 0.1 mg / cubic millimeter higher, and more preferably at least 0.2 mg / cubic millimeter higher, than the density of the first plug. 5. A heated aerosol-generating article according to 2, 3 or 4, wherein the density of the second plug is 0.65 mg / cubic millimeter to 0.85 mg / cubic millimeter, and the density of the first plug is 0.45 mg / cubic millimeter to 0.65 mg / cubic millimeter. 6. The heated aerosol-generating article according to any one of 1 to 5, wherein the second plug has a higher withdrawal resistance than the first plug. 7. The heated aerosol-generating article according to any one of 1 to 6, wherein the first plug and the second plug each contain an aerosol former, and the composition of the aerosol former in the first plug is different from the composition of the aerosol former in the second plug. 8. The heated aerosol-generating article described in 7, wherein the first plug and the second plug each contain an aerosol former including glycerol, and the glycerol content of the second plug is at least 2 weight percent higher, and more preferably at least 5 weight percent higher, than the glycerol content of the first plug on a dry weight basis. 9. The heated aerosol-generating article described in 7 or 8, wherein the aerosol former of at least the first plug further contains propylene glycol, and the propylene glycol content of the first plug is at least 2 weight percent higher on a dry weight basis than the propylene glycol content of the second plug. 10. The heated aerosol-generating article described in 8 or 9, wherein the second plug contains more than 15 weight percent glycerol and 4 weight percent or less propylene glycol on a dry weight basis, and the first plug contains 15 weight percent or less glycerol and at least 5 weight percent propylene glycol on a dry weight basis. 11. The heated aerosol-generating article described in 10, wherein the second plug contains 17 to 25 weight percent glycerol and 0 to 4 weight percent propylene glycol on a dry weight basis, and the first plug contains 5 to 15 weight percent glycerol and 5 to 15 weight percent propylene glycol on a dry weight basis. 12. A heated aerosol-generating article according to any one of 8 to 11, wherein each of the plugs of homogenized tobacco material comprises 15 to 25 weight percent of an aerosol former on a dry weight basis. 13. A heated aerosol-generating article according to any one of 1 to 12, wherein at least one of the plugs of homogenized tobacco material is formed from one or more sheets of homogenous tobacco material. 14. An aerosol generating system comprising: an aerosol-generating article according to any one of claims 1 to 13; an aerosol generating device adapted to receive the aerosol-generating article, the aerosol generating device comprising a heater element configured to heat both the first plug and the second plug of homogenized tobacco material during use, wherein upon heating of the aerosol-generating substrate by the heater element, the first plug releases an aerosol faster than the second plug of homogenized tobacco material. 15. The aerosol generation system described in 14, wherein the heater element is a heater blade configured to be inserted into the first plug and the second release plug during use. 16. A method for at least partially producing a rod of aerosol-generating substrate for an aerosol-generating article according to any one of claims 1 to 15, said method comprising: providing a first plug of homogenized tobacco material; providing a second plug of homogenized tobacco material, the second plug differing from the first plug in at least one property of the homogenized tobacco material such that the first plug releases an aerosol after a shorter time than the second plug upon heating of the aerosol-generating substrate; combining the first plug and the second plug so that the first plug and the second plug are coaxially aligned and the first plug is disposed downstream of the second plug; packaging the combined first and second plugs to form a rod of aerosol-generating substrate. 17. A rod for use as an aerosol-generating substrate in an aerosol-generating article, said rod comprising: a first plug of homogenized tobacco material; a second plug of homogenized tobacco material downstream of the first plug of aerosol-generating material, the first plug and the second plug being coaxially aligned, the first plug being provided downstream of the second plug, and the first plug and the second plug differ from each other in at least one property of the homogenized tobacco material such that upon heating of the rod during use, the first plug releases an aerosol after a shorter time than the second plug.

Claims

1. 1. A heated aerosol-generating article comprising a rod of an aerosol-generating substrate, the rod of the aerosol-generating substrate comprising: a first plug containing an aerosol former; a second plug containing an aerosol former; the first plug and the second plug are coaxially aligned, and the first plug is located downstream of the second plug; the second plug has a higher density than the first plug; the second plug contains a greater amount of glycerol than the first plug; Heated aerosol-generating products.

2. 2. The heated aerosol-generating article of claim 1, wherein the density of the second plug is at least 10 percent higher than the density of the first plug.

3. 3. The heated aerosol-generating article according to claim 1, wherein the density of the second plug is at least 15 percent higher than the density of the first plug.

4. 4. The heated aerosol-generating article according to claim 1, wherein the density of the second plug is at least 20 percent higher than the density of the first plug.

5. 5. The heated aerosol-generating article according to claim 1, wherein the density of the second plug is at least 0.1 mg per cubic millimeter higher than the density of the first plug.

6. 6. The heated aerosol-generating article according to claim 1, wherein the density of the second plug is less than 0.85 mg per cubic millimeter.

7. 7. The heated aerosol-generating article according to claim 1, wherein the density of the first plug is less than 0.65 mg per cubic millimeter.

8. 8. The heated aerosol-generating article according to claim 1, wherein the glycerol content of the second plug is at least 2% by weight greater, on a dry weight basis, than the glycerol content of the first plug.

9. 9. The heated aerosol-generating article according to claim 1, wherein the glycerol content of the second plug is at least 5% by weight greater, on a dry weight basis, than the glycerol content of the first plug.

10. 10. The heated aerosol-generating article of claim 1, wherein the glycerol content of the second plug is at least 8% by weight, on a dry weight basis, greater than the glycerol content of the first plug.

11. The heated aerosol-generating article according to any one of claims 1 to 10, wherein the second plug has a higher resistance to withdrawal than the first plug.

12. The heated aerosol-generating article according to any one of claims 1 to 11, wherein the first plug and the second plug have different lengths.

13. The heated aerosol-generating article according to any one of claims 1 to 12, wherein the first plug and the second plug are disposed in an end-to-end abutting relationship.

14. The heated aerosol-generating article according to any one of claims 1 to 13, wherein the first plug and the second plug are individually packaged.

15. 14. The heated aerosol-generating article according to claim 1, further comprising a hollow acetate tube located immediately downstream of the rod of the aerosol-generating substrate.

16. The heated aerosol-generating article according to any one of claims 1 to 15, wherein the first plug is a first plug of homogenized tobacco material.

17. The heated aerosol-generating article according to any one of claims 1 to 16, wherein the second plug is a second plug of homogenized tobacco material.

18. 18. The heated aerosol-generating article of any one of claims 1 to 17, wherein the first plug is a first plug of homogenized tobacco material, the second plug is a second plug of homogenized tobacco material, and the first plug and the second plug differ from each other in at least one property of the homogenized tobacco material.

19. 19. The heated aerosol-generating article according to claim 1, wherein the first plug and the second plug differ from each other in at least one property such that, upon heating of the aerosol-generating substrate, the first plug releases an aerosol after a shorter time than the second plug.

20. An aerosol-generating article according to any one of claims 1 to 19; an aerosol generating device adapted to receive the aerosol-generating article, the aerosol generating device including a heater element configured to heat both the first plug and the second plug during use.

21. 21. The aerosol generation system of claim 20, wherein the heater element is an external heater configured to at least partially surround the first plug and the second plug and heat both the first plug and the second plug from the outside.

22. A method for at least partially producing a rod of aerosol-generating substrate for an aerosol-generating article according to any one of claims 1 to 19, comprising the steps of: providing a first plug containing an aerosol former; providing a second plug comprising an aerosol former, said second plug having a higher density than said first plug and said second plug comprising a greater amount of glycerol than said first plug; combining the first plug and the second plug so that the first plug and the second plug are coaxially aligned and the first plug is disposed downstream of the second plug; packaging the combined first and second plugs to form a rod of aerosol-generating substrate.

23. 1. A rod for use as an aerosol-generating substrate in an aerosol-generating article, comprising: a first plug containing an aerosol former; a second plug containing an aerosol former; the first plug and the second plug are coaxially aligned, and the first plug is located downstream of the second plug; the second plug has a higher density than the first plug; the second plug contains a greater amount of glycerol than the first plug; rod.

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