Combustible heat source containing ignition aids and binders

Abstract

A combustible heat source for an aerosol-generating article, comprising: carbon; an alkaline earth metal peroxide ignition aid; and a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether, preferably selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.

Description

[Technical Field]

[0001] The present invention relates to a combustible heat source for an aerosol-generating article, and to an aerosol-generating article comprising a combustible heat source and an aerosol-forming substrate downstream of the combustible heat source. [Background technology]

[0002] A number of aerosol-generating articles have been proposed in the industry in which tobacco material is heated rather than burned. One purpose of these "heat-and-burn" aerosol-generating articles is to reduce known harmful smoke components of the type produced by the combustion and thermal decomposition of tobacco in conventional cigarettes.

[0003] In heated aerosol-generating articles, the aerosol is typically generated by heat transfer from a heat source, e.g., a chemical, electrical, or combustible heat source, to a physically separate aerosol-forming substrate that may be located within, around, or downstream from the heat source.

[0004] In one type of heated aerosol-generating article, an aerosol is generated by heat transfer from a combustible carbonaceous heat source to a physically separate aerosol-forming substrate containing tobacco material located downstream of the combustible carbonaceous heat source. During use, volatile compounds are released from the tobacco material by heat transfer from the combustible carbonaceous heat source to the aerosol-forming substrate and become entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user.

[0005] Heat can be transferred from the combustible carbonaceous heat source to the aerosol-forming substrate by one or both of forced convection and conduction.

[0006] To ensure sufficient conductive heat transfer from the combustible carbonaceous heat source to the aerosol-forming substrate to obtain an acceptable aerosol, it is known to include a heat-conducting element around and in direct contact with at least a rear portion of the combustible carbonaceous heat source and at least a front portion of the aerosol-forming substrate of a heated aerosol-generating article. For example, WO2009 / 022232A2 discloses a smoking article comprising a combustible carbonaceous heat source, an aerosol-forming substrate downstream of the combustible heat source, and a heat-conducting element around and in contact with the rear portion of the combustible carbonaceous heat source and the adjacent front portion of the aerosol-forming substrate. During use, the heat generated during the combustion of the combustible carbonaceous heat source is transferred to the periphery of the front portion of the aerosol-forming substrate by conduction through the adjacent downstream end of the combustible carbonaceous heat source and the heat-conducting element.

[0007] The combustion temperature of a combustible heat source for use in a heated aerosol-generating article should not be so high as to result in combustion or thermal decomposition of the aerosol-forming substrate during use of the heated aerosol-generating article, but should be high enough to generate enough heat to release enough volatile compounds from the aerosol-forming substrate to produce an acceptable aerosol, particularly during the first draw.

[0008] A variety of combustible carbonaceous heat sources are known in the art for use in heated aerosol-generating articles.

[0009] When used in heated aerosol-generating articles, known combustible carbonaceous heat sources often do not generate enough heat after ignition to produce an acceptable aerosol during the first draw.

[0010] When used in heated aerosol-generating articles, known combustible carbonaceous heat sources are often difficult to ignite. Failure to properly ignite a combustible carbonaceous heat source in a heated aerosol-generating article can result in an unacceptable aerosol being delivered to the user.

[0011] Inclusion of oxidizers and other additives in combustible carbonaceous heat sources has been proposed to improve their ignition and combustion characteristics. For example, WO 2012 / 164077 A1 discloses a combustible heat source for a smoking article comprising carbon and at least one ignition aid selected from the group consisting of metal nitrates, chlorates, peroxides, thermic materials, intermetallic materials, magnesium, zirconium, and combinations thereof, having a thermal decomposition temperature of less than about 600 degrees Celsius.

[0012] Some ignition aids used in known combustible carbonaceous heat sources have been found to decompose upon exposure to environmental conditions during transportation and storage of the combustible carbonaceous heat source. For example, some ignition aids used in known combustible carbonaceous heat sources have been found to decompose upon exposure to atmospheric moisture during transportation and storage of the combustible carbonaceous heat source. Decomposition of the ignition aid during transportation and storage can disadvantageously make it more difficult to ignite known carbonaceous combustible heat sources that include the ignition aid source.

[0013] It would be desirable to provide a combustible carbonaceous heat source that includes an ignition aid that exhibits rapid ignition and mechanical integrity, even after exposure to environmental conditions.

[0014] It would be desirable to provide a combustible carbonaceous heat source containing an ignition aid that exhibits improved combustion characteristics compared to known combustible carbonaceous heat sources containing ignition aids. Summary of the Invention

[0015] The present invention relates to a combustible heat source for an aerosol-generating article. The combustible heat source may include carbon. The combustible heat source may include an ignition aid. The ignition aid may be an alkaline earth metal peroxide. The combustible heat source may include a binder. The binder may include carboxymethyl cellulose. The binder may include at least one additional cellulose ether. The binder may include a combination of carboxymethyl cellulose and at least one additional cellulose ether.

[0016] In accordance with the present invention, there is provided a combustible heat source for an aerosol-generating article, comprising carbon, an alkaline earth metal peroxide ignition aid, and a binder comprising at least one cellulose ether, wherein the binder is free of non-combustible inorganic sheet silicate binders.

[0017] According to the present invention, there is provided a combustible heat source for an aerosol-generating article, comprising carbon, an alkaline earth metal peroxide ignition aid, and a binder containing at least one cellulose ether selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose, wherein the binder is free of non-combustible inorganic sheet silicate binders.

[0018] According to the present invention, there is provided a combustible heat source for an aerosol-generating article, the combustible heat source comprising carbon, an alkaline earth metal peroxide ignition aid, and a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether.

[0019] The present invention further provides an aerosol-generating article comprising a combustible heat source according to the present invention and an aerosol-forming substrate downstream of the combustible heat source.

[0020] Surprisingly, it has been found that by including a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in a combustible heat source according to the present invention, decomposition of the alkaline earth metal peroxide ignition aid as a result of exposure to environmental conditions can be advantageously reduced.

[0021] In particular, it has surprisingly been found that by including a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in a combustible heat source according to the present invention, decomposition of the alkaline earth metal peroxide ignition aid as a result of exposure to high humidity can be reduced.

[0022] Without wishing to be bound by theory, it is believed that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether reduces the overall hydrophilicity and hygroscopicity of the combustible heat source according to the present invention.

[0023] By reducing the decomposition of the alkaline earth metal peroxide ignition aid, the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether may advantageously improve the chemical and physical stability of the combustible heat source according to the present invention during transportation and storage of the combustible heat source.

[0024] It has also surprisingly been found that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in combination with an alkaline earth metal peroxide ignition aid can advantageously significantly improve the combustion characteristics of the combustible heat source according to the present invention.

[0025] In particular, it has been surprisingly found that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in combination with an alkaline earth metal peroxide ignition aid can advantageously significantly improve the ignition propagation rate of a combustible heat source according to the present invention.

[0026] Without wishing to be bound by theory, it is believed that the binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether provides energy during ignition of the combustible heat source according to the present invention, which, without wishing to be bound by theory, is believed to improve the ignition propagation rate of the combustible heat source according to the present invention.

[0027] It has also surprisingly been found that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether can advantageously improve the mechanical properties of the combustible heat source according to the present invention.

[0028] Without wishing to be bound by theory, it is believed that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether modifies the aggregation of the carbon and alkaline earth metal peroxide ignition aid during the formation of the combustible heat source according to the present invention, which, without wishing to be bound by theory, is believed to affect the mechanical properties of the combustible heat source according to the present invention.

[0029] As used herein in connection with embodiments of the present invention, the terms "distal," "upstream," and "forward," as well as "proximal," "downstream," and "rearward," are used to describe the relative positions of components, or portions of components, of an aerosol-generating article according to the present invention. An aerosol-generating article according to the present invention comprises a proximal end through which aerosol exits the aerosol-generating article for delivery to a user during use. The proximal end of the aerosol-generating article may also be referred to as the mouth end of the aerosol-generating article. During use, a user draws on the proximal end of the aerosol-generating article to inhale the aerosol generated by the aerosol-generating article.

[0030] The aerosol-generating article according to the present invention has a distal end. The combustible heat source is located at or proximate to the distal end of the aerosol-generating article. The mouth end of the aerosol-generating article is downstream of the distal end of the aerosol-generating article. The proximal end of the aerosol-generating article may also be referred to as the downstream end of the aerosol-generating article, and the distal end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article. Components or portions of components of the aerosol-generating article according to the present invention may be described as being upstream or downstream of each other based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article.

[0031] The combustible heat source according to the present invention has a front end surface and a rear end surface. The front end surface of the combustible heat source is at the upstream end of the combustible heat source. The upstream end of the combustible heat source is the end of the combustible heat source that is farthest from the proximal end of the aerosol-generating article. The rear end surface of the combustible heat source is at the downstream end of the combustible heat source. The downstream end of the combustible heat source is the end of the combustible heat source that is closest to the proximal end of the aerosol-generating article.

[0032] As used herein in connection with the present invention, the term "longitudinal" is used to describe the direction between the upstream and downstream ends of a combustible heat source according to the present invention and an aerosol-generating article according to the present invention.

[0033] The term "transverse direction" as used herein in connection with the present invention is used to describe a direction perpendicular to the longitudinal axis, i.e., perpendicular to the direction between the upstream and downstream ends of a combustible heat source according to the present invention and an aerosol-generating article according to the present invention.

[0034] As used herein in connection with the present invention, the term "length" is used to describe the greatest dimension along the longitudinal axis of a combustible heat source according to the present invention and an aerosol-generating article according to the present invention.

[0035] As used herein in connection with the present invention, the term "diameter" is used to describe the largest transverse dimension of a combustible heat source according to the present invention and an aerosol-generating article according to the present invention.

[0036] The combustible heat source according to the present invention is a carbonaceous heat source.

[0037] As used herein in connection with the present invention, the term "carbonaceous" is used to describe a combustible heat source that contains carbon.

[0038] The combustible heat source according to the present invention comprises carbon as a fuel.

[0039] The combustible heat source may include at least about 25 weight percent carbon.

[0040] Unless otherwise specified, the weight percentages of the components of the combustible heat source listed herein are based on the total dry weight of the combustible heat source.

[0041] Preferably, the combustible heat source comprises at least about 30 weight percent carbon.

[0042] More preferably, the combustible heat source comprises at least about 35 weight percent carbon.

[0043] The combustible heat source may include at least about 40 weight percent carbon.

[0044] The combustible heat source may include up to about 60 weight percent carbon.

[0045] Preferably, the combustible heat source comprises no more than about 55 weight percent carbon.

[0046] More preferably, the combustible heat source comprises no more than about 50 weight percent carbon.

[0047] The combustible heat source may include up to about 45 weight percent carbon.

[0048] The combustible heat source may include about 25 weight percent to about 60 weight percent carbon, about 25 weight percent to about 55 weight percent carbon, about 25 weight percent to about 50 weight percent carbon, or about 25 weight percent to about 45 weight percent carbon.

[0049] Preferably, the combustible heat source comprises about 30 weight percent to about 60 weight percent carbon, about 30 weight percent to about 55 weight percent carbon, about 30 weight percent to about 50 weight percent carbon, or about 30 weight percent to about 45 weight percent carbon.

[0050] More preferably, the combustible heat source comprises between about 35 weight percent and about 60 weight percent carbon, between about 35 weight percent and about 55 weight percent carbon, between about 35 weight percent and about 50 weight percent carbon, or between about 35 weight percent and about 45 weight percent carbon.

[0051] The combustible heat source may include about 40 weight percent to about 60 weight percent carbon, about 40 weight percent to about 55 weight percent carbon, about 40 weight percent to about 50 weight percent carbon, or about 40 weight percent to about 45 weight percent carbon.

[0052] Combustible heat sources according to the present invention may be formed using one or more suitable carbonaceous materials. Advantageously, combustible heat sources according to the present invention include one or more carbonized materials. Suitable carbonaceous materials are known in the art and include, but are not limited to, carbon powder and charcoal powder.

[0053] The combustible heat source according to the present invention comprises an alkaline earth metal peroxide ignition aid.

[0054] As used herein in connection with the present invention, the term "alkaline earth metal peroxide ignition aid" is used to describe an alkaline earth metal peroxide that releases energy and / or oxygen during ignition of a combustible heat source, wherein the rate of release of energy and / or oxygen by the alkaline earth metal peroxide is not diffused into ambient oxygen. In other words, the rate of release of energy and / or oxygen by the alkaline earth metal peroxide during ignition of a combustible heat source is largely independent of the rate at which ambient oxygen can reach the alkaline earth metal peroxide.

[0055] The amount of energy and / or oxygen released by the alkaline earth metal peroxide ignition aid during ignition of a combustible heat source may be sufficient to cause the combustible heat source to undergo a two-stage combustion process.

[0056] In an initial first stage, a combustible heat source according to the present invention may experience a "boost" in temperature, and in a subsequent second stage, a combustible heat source according to the present invention may undergo sustained combustion at a lower "run" temperature.

[0057] An initial "boost" in the temperature of a combustible heat source according to the present invention may occur due to the very rapid propagation of heat throughout the combustible heat source upon ignition of a portion thereof. The very rapid propagation of heat may be the result of a chain reaction in which an ignited portion of the combustible heat source triggers the ignition of an adjacent unignited portion of the combustible heat source.

[0058] In use, in an aerosol-generating article according to the present invention, a rapid increase in temperature of the combustible heat source according to the present invention to the "boost" temperature can rapidly increase the temperature of the aerosol-forming substrate to a level at which volatile compounds are released from the aerosol-forming substrate. This can ensure that the aerosol-generating article according to the present invention produces a sensorially acceptable aerosol during the first draw. A subsequent decrease in temperature of the combustible heat source according to the present invention to the "run" temperature can ensure that the temperature of the aerosol-forming substrate does not reach a level at which combustion or thermal decomposition of the aerosol-forming substrate occurs.

[0059] Controlling the temperature of the combustible heat source according to the present invention in the manner described above may advantageously make it possible to provide an aerosol-generating article that not only produces a sensory acceptable aerosol during the first draw, but also substantially avoids combustion or thermal decomposition of the aerosol-forming substrate.

[0060] The amount of alkaline earth metal peroxide ignition aid that needs to be included to achieve the above-described two-stage process will vary depending on the particular alkaline earth metal peroxide ignition aid included in the combustible heat source.

[0061] Generally, the greater the amount of energy and / or oxygen released by the alkaline earth metal peroxide ignition aid per unit mass of the alkaline earth metal peroxide ignition aid, the less alkaline earth metal peroxide ignition aid needs to be included in the combustible heat source to achieve the two-stage combustion process described above.

[0062] The combustible heat source may include at least about 15 weight percent of an alkaline earth metal peroxide ignition aid.

[0063] Preferably, the combustible heat source comprises at least about 20 weight percent alkaline earth metal peroxide ignition aid.

[0064] More preferably, the combustible heat source comprises at least about 30 weight percent alkaline earth metal peroxide ignition aid.

[0065] The combustible heat source may include at least about 40 weight percent alkaline earth metal peroxide ignition aid.

[0066] The combustible heat source may include up to about 65 weight percent of an alkaline earth metal peroxide ignition aid.

[0067] The combustible heat source preferably includes up to about 60 weight percent alkaline earth metal peroxide ignition aid.

[0068] More preferably, the combustible heat source comprises up to about 55 weight percent alkaline earth metal peroxide ignition aid.

[0069] The combustible heat source may include up to about 50 weight percent of an alkaline earth metal peroxide ignition aid.

[0070] The combustible heat source may include about 15 weight percent to about 65 weight percent alkaline earth metal peroxide ignition aid, about 15 weight percent to about 60 weight percent alkaline earth metal peroxide ignition aid, about 15 weight percent to about 55 weight percent alkaline earth metal peroxide ignition aid, or about 15 weight percent to about 50 weight percent alkaline earth metal peroxide ignition aid.

[0071] Preferably, the combustible heat source comprises about 20 weight percent to about 65 weight percent alkaline earth metal peroxide ignition aid, about 20 weight percent to about 60 weight percent alkaline earth metal peroxide ignition aid, about 20 weight percent to about 55 weight percent alkaline earth metal peroxide ignition aid, or about 20 weight percent to about 50 weight percent alkaline earth metal peroxide ignition aid.

[0072] More preferably, the combustible heat source comprises about 30 weight percent to about 65 weight percent alkaline earth metal peroxide ignition aid, about 30 weight percent to about 60 weight percent alkaline earth metal peroxide ignition aid, about 30 weight percent to about 55 weight percent alkaline earth metal peroxide ignition aid, or about 30 weight percent to about 50 weight percent alkaline earth metal peroxide ignition aid.

[0073] The combustible heat source may include about 40 weight percent to about 65 weight percent alkaline earth metal peroxide ignition aid, 40 weight percent to about 60 weight percent alkaline earth metal peroxide ignition aid, about 40 weight percent to about 55 weight percent alkaline earth metal peroxide ignition aid, or about 40 weight percent to about 50 weight percent alkaline earth metal peroxide ignition aid.

[0074] Preferably, the alkaline earth metal peroxide ignition aid is calcium peroxide.

[0075] The combustible heat source may include at least about 15 weight percent calcium peroxide.

[0076] Preferably, the combustible heat source comprises at least about 20 weight percent calcium peroxide.

[0077] More preferably, the combustible heat source comprises at least about 30 weight percent calcium peroxide.

[0078] The combustible heat source may include at least about 40 weight percent calcium peroxide.

[0079] The combustible heat source may include up to about 65 weight percent calcium peroxide.

[0080] Preferably, the combustible heat source comprises up to about 60 weight percent calcium peroxide.

[0081] More preferably, the combustible heat source comprises up to about 55 weight percent calcium peroxide.

[0082] The combustible heat source may include up to about 50 weight percent calcium peroxide.

[0083] The combustible heat source may include about 15 weight percent to about 65 weight percent calcium peroxide, about 15 weight percent to about 60 weight percent calcium peroxide, about 15 weight percent to about 55 weight percent calcium peroxide, or about 15 weight percent to about 50 weight percent calcium peroxide.

[0084] Preferably, the combustible heat source comprises about 20 weight percent to about 65 weight percent calcium peroxide, about 20 weight percent to about 60 weight percent calcium peroxide, about 20 weight percent to about 55 weight percent calcium peroxide, or about 20 weight percent to about 50 weight percent calcium peroxide.

[0085] More preferably, the combustible heat source comprises about 30 weight percent to about 65 weight percent calcium peroxide, about 30 weight percent to about 60 weight percent calcium peroxide, about 30 weight percent to about 55 weight percent calcium peroxide, or about 30 weight percent to about 50 weight percent calcium peroxide.

[0086] The combustible heat source may include about 40 weight percent to about 65 weight percent calcium peroxide, about 40 weight percent to about 60 weight percent calcium peroxide, about 40 weight percent to about 55 weight percent calcium peroxide, or about 40 weight percent to about 50 weight percent calcium peroxide.

[0087] The combustible heat source according to the present invention is a solid combustible heat source.

[0088] Preferably, the combustible heat source is a monolithic solid combustible heat source, i.e., a single piece of solid combustible heat source.

[0089] A combustible heat source according to the present invention comprises a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose.

[0090] As used herein in connection with the present invention, the term "binder" is used to describe a component of the combustible heat source that has the ability to bind together the carbon and alkaline earth metal peroxide ignition aid and any other components of the combustible heat source.

[0091] As used herein in connection with the present invention, the term "additional cellulose ether" is used to describe cellulose ethers other than carboxymethyl cellulose.

[0092] The combustible heat source may include at least about 3 weight percent binder.

[0093] Preferably, the combustible heat source comprises at least about 4 weight percent binder.

[0094] More preferably, the combustible heat source comprises at least about 5 weight percent binder.

[0095] The combustible heat source may include up to about 20 weight percent binder.

[0096] Preferably, the combustible heat source comprises no more than about 15 weight percent binder.

[0097] More preferably, the combustible heat source comprises no more than about 10 weight percent binder.

[0098] The combustible heat source may include between about 3 weight percent and about 20 weight percent binder, between about 3 weight percent and about 15 weight percent binder, or between about 3 weight percent and about 10 weight percent binder.

[0099] Preferably, the combustible heat source comprises between about 4 weight percent and about 20 weight percent binder, between about 4 weight percent and about 15 weight percent binder, or between about 4 weight percent and about 10 weight percent binder.

[0100] More preferably, the combustible heat source comprises between about 5 weight percent and about 20 weight percent binder, between about 5 weight percent and about 15 weight percent binder, or between about 5 weight percent and about 10 weight percent binder.

[0101] The binder includes carboxymethyl cellulose.

[0102] The combustible heat source may include at least about 1.5 weight percent carboxymethyl cellulose.

[0103] Preferably, the combustible heat source comprises at least about 2 weight percent carboxymethyl cellulose.

[0104] More preferably, the combustible heat source comprises at least about 3 weight percent carboxymethyl cellulose.

[0105] The combustible heat source may include up to about 15 weight percent carboxymethyl cellulose.

[0106] Preferably, the combustible heat source comprises up to about 12 weight percent carboxymethyl cellulose.

[0107] More preferably, the combustible heat source comprises up to about 8 weight percent carboxymethyl cellulose.

[0108] The combustible heat source may include about 1.5 weight percent to about 15 weight percent carboxymethyl cellulose, about 1.5 weight percent to about 12 weight percent carboxymethyl cellulose, or about 1.5 weight percent to about 8 weight percent carboxymethyl cellulose.

[0109] Preferably, the combustible heat source comprises from about 2 weight percent to about 15 weight percent carboxymethylcellulose, from about 2 weight percent to about 12 weight percent carboxymethylcellulose, or from about 2 weight percent to about 8 weight percent carboxymethylcellulose.

[0110] More preferably, the combustible heat source comprises from about 3 weight percent to about 15 weight percent carboxymethylcellulose, from about 3 weight percent to about 12 weight percent carboxymethylcellulose, or from about 3 weight percent to about 8 weight percent carboxymethylcellulose.

[0111] The binder includes at least one additional cellulose ether.

[0112] The combustible heat source may include at least about 0.2 weight percent of at least one additional cellulose ether.

[0113] The combustible heat source may include at least about 0.5 weight percent of at least one additional cellulose ether.

[0114] Preferably, the combustible heat source comprises at least about 0.75 weight percent of at least one additional cellulose ether.

[0115] More preferably, the combustible heat source comprises at least about 1 weight percent of at least one additional cellulose ether.

[0116] The combustible heat source may include up to about 6 weight percent of at least one additional cellulose ether.

[0117] Preferably, the combustible heat source comprises up to about 5 weight percent of at least one additional cellulose ether.

[0118] More preferably, the combustible heat source comprises up to about 4 weight percent of at least one additional cellulose ether.

[0119] The combustible heat source may include up to about 3 weight percent of at least one additional cellulose ether.

[0120] The combustible heat source may comprise from about 0.2 weight percent to about 6 weight percent of at least one additional cellulose ether, from about 0.2 weight percent to about 5 weight percent of at least one additional cellulose ether, from about 0.5 weight percent to about 4 weight percent of at least one additional cellulose ether, or from about 0.5 weight percent to about 3 weight percent of at least one additional cellulose ether.

[0121] The combustible heat source may comprise from about 0.5 weight percent to about 6 weight percent of at least one additional cellulose ether, from about 0.5 weight percent to about 5 weight percent of at least one additional cellulose ether, from about 0.5 weight percent to about 4 weight percent of at least one additional cellulose ether, or from about 0.5 weight percent to about 3 weight percent of at least one additional cellulose ether.

[0122] Preferably, the combustible heat source comprises between about 0.75 weight percent and about 6 weight percent additional cellulose ether, between about 0.75 weight percent and about 5 weight percent additional cellulose ether, between about 0.75 weight percent and about 4 weight percent additional cellulose ether, or between about 0.75 weight percent and about 3 weight percent additional cellulose ether.

[0123] More preferably, the combustible heat source comprises between about 1 weight percent and about 6 weight percent additional cellulose ether, between about 1 weight percent and about 5 weight percent additional cellulose ether, between about 1 weight percent and about 4 weight percent additional cellulose ether, or between about 1 weight percent and about 3 weight percent additional cellulose ether.

[0124] The binder comprises a combination of carboxymethyl cellulose and at least one additional cellulose ether.

[0125] Preferably, the binder comprises a combination of carboxymethyl cellulose and at least one additional cellulose ether selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose.

[0126] The ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source may be at least about 1:1.

[0127] Preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source is at least about 3:2.

[0128] More preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source can be at least about 2:1.

[0129] The ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source may be about 4:1 or less.

[0130] Preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source can be about 7:2 or less.

[0131] More preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source can be about 3:1 or less.

[0132] The ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source may be about 5:2 or less.

[0133] The ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source can be from about 1:1 to about 4:1, from about 1:1 to about 7:2, from about 1:1 to about 3:1, or from about 1:1 to about 5:2.

[0134] Preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source is from about 3:2 to about 4:1, from about 3:2 to about 7:2, from about 3:2 to about 3:1, or from about 3:2 to about 5:2.

[0135] More preferably, the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source is from about 2:1 to about 4:1, from about 2:1 to about 7:2, from about 2:1 to about 3:1, or from about 2:1 to about 5:2.

[0136] The binder may include a non-combustible inorganic sheet silicate binder.

[0137] As used herein in connection with the present invention, the term "non-flammable" is used to describe components that do not burn or decompose at temperatures reached during ignition or combustion of a combustible heat source.

[0138] As used herein in connection with the present invention, the term "non-combustible inorganic sheet silicate binder" is used to describe an inorganic sheet silicate binder that is stable at the temperatures to which the binder is subjected during ignition and combustion of a combustible heat source, and that remains substantially intact during and after combustion of the combustible heat source.

[0139] Suitable non-combustible inorganic sheet silicate binders include, but are not limited to, clays such as bentonite, montmorillonite, and kaolinite, mica, and serpentine.

[0140] As used herein in connection with the present invention, the term "clay" is used to describe an aluminum phyllosilicate material formed from two-dimensional sheets of silicate and aluminate ions, which form a distinct layered structure within the clay.

[0141] Advantageously, the binder may be free of non-combustible inorganic sheet silicate binders.

[0142] A combustible heat source according to the present invention may include one or more carboxylic acid combustion salts.

[0143] As used herein in connection with the present invention, the term "carboxylic acid combustion salt" is used to describe salts of carboxylic acids other than carbonic acid, i.e., the term "carboxylic acid combustion salt" as used herein in connection with the present invention does not include carbonates or bicarbonates.

[0144] One or more carboxylic acid combustion salts may advantageously promote the combustion of a combustible heat source.

[0145] The carboxylic acid combustion salts may include a monovalent, divalent, or trivalent cation and a carboxylate anion.

[0146] The carboxylic acid combustion salts may include monovalent, divalent, or trivalent cations and acetate, citrate, or succinate anions.

[0147] The carboxylic acid combustion salt may be an alkali metal carboxylic acid combustion salt, for example, the carboxylic acid combustion salt may be a sodium carboxylic acid combustion salt or a potassium carboxylic acid combustion salt.

[0148] The carboxylic acid combustion salt may be an alkali metal acetate, an alkali metal citrate, or an alkali metal succinate.

[0149] Most preferably, the carboxylic acid combustion salt is potassium citrate.

[0150] The combustible heat source may include a single carboxylic acid combustion salt.

[0151] The combustible heat source may include a combination of two or more different carboxylic acid fuel salts. The two or more different carboxylic acid fuel salts may include different carboxylic acid anions. The two or more different carboxylic acid fuel salts may include different anions. For example, the combustible heat source may include a combination of an alkali metal citrate and an alkaline earth metal succinate.

[0152] The combustible heat source may include at least about 0.1 weight percent of one or more carboxylic acid combustion salts.

[0153] The combustible heat source may include at least about 0.5 weight percent of one or more carboxylic acid combustion salts.

[0154] The combustible heat source preferably comprises at least about 1 weight percent of one or more carboxylic acid combustion salts.

[0155] The combustible heat source may include up to about 4 weight percent of one or more carboxylic acid combustion salts.

[0156] Preferably, the combustible heat source comprises up to about 3 weight percent of one or more carboxylic acid combustion salts.

[0157] The combustible heat source may include from about 0.1 weight percent to about 4 weight percent of one or more carboxylic acid combustion salts, or from about 0.1 weight percent to about 3 weight percent of one or more carboxylic acid combustion salts.

[0158] The combustible heat source may include from about 0.5 weight percent to about 4 weight percent of one or more carboxylic acid combustion salts, or from about 0.5 weight percent to about 3 weight percent of one or more carboxylic acid combustion salts.

[0159] Preferably, the combustible heat source comprises from about 1 weight percent to about 4 weight percent of one or more carboxylic acid combustion salts, or from about 1 weight percent to about 3 weight percent of one or more carboxylic acid combustion salts.

[0160] Combustible heat sources according to the present invention are preferably substantially homogeneous in composition.

[0161] A combustible heat source according to the present invention may have any desired length.

[0162] A combustible heat source according to the present invention may have a length of from about 5 millimeters to about 20 millimeters.

[0163] Combustible heat sources according to the present invention preferably have a length of from about 7 millimeters to about 17 millimeters.

[0164] More preferably, combustible heat sources according to the present invention have a length of from about 7 millimeters to about 15 millimeters.

[0165] Most preferably, combustible heat sources according to the present invention have a length of from about 7 millimeters to about 13 millimeters.

[0166] Combustible heat sources according to the present invention may have any desired diameter.

[0167] Combustible heat sources according to the present invention may have a diameter of from about 5 millimeters to about 15 millimeters.

[0168] Combustible heat sources according to the present invention preferably have a diameter of about 5 millimeters to about 10 millimeters.

[0169] More preferably, combustible heat sources according to the present invention have a diameter of about 7 millimeters to about 8 millimeters.

[0170] Combustible heat sources according to the present invention may be tapered such that the diameter of the rear portion of the combustible heat source is greater than the diameter of the front portion of the combustible heat source.

[0171] Combustible heat sources according to the present invention are preferably of substantially constant diameter.

[0172] Combustible heat sources according to the present invention are preferably of substantially circular transverse cross-section.

[0173] Combustible heat sources according to the present invention are preferably substantially cylindrical.

[0174] A combustible heat source according to the present invention may have a mass of about 300 milligrams to about 500 milligrams. For example, a combustible heat source according to the present invention has a mass of about 400 milligrams to about 450 milligrams.

[0175] Combustible heat sources according to the present invention may have an apparent density of from about 0.6 grams per cubic centimeter to about 1.0 grams per cubic centimeter.

[0176] Combustible heat sources according to the present invention may have a porosity of from about 20 percent to about 80 percent as measured, for example, by mercury porosimetry or helium pycnometry.

[0177] For example, a combustible heat source according to the present invention may have a porosity of about 20 percent to about 60 percent, about 50 percent to about 70 percent, or about 50 percent to about 60 percent, as measured, for example, by mercury porosimetry or helium pycnometry.

[0178] The desired porosity can be readily achieved during production of the combustible heat source of the present invention using conventional methods and techniques.

[0179] A combustible heat source according to the present invention may be formed by combining one or more carbon materials, an alkaline earth metal peroxide ignition aid, a binder, and any other components of the combustible heat source to form a mixture and forming the mixture into a desired shape.

[0180] Combustible heat sources according to the present invention are preferably formed by combining one or more carbon materials, alkaline earth metal peroxide ignition aids, binders, and any other components of the combustible heat source to form a granular mixture, and forming the granular mixture into a desired shape.

[0181] Advantageously, the binder is dispersed in intergranular and intragranular locations in the granular mixture.

[0182] One or more carbonaceous materials, alkaline earth metal peroxide ignition aids, binders, and any other components of the combustible heat source may be combined to form a mixture using any suitable known method, such as, for example, dry granulation, wet granulation, high shear mixing, spheronization, or extrusion.

[0183] Preferably, the one or more carbonaceous materials, alkaline earth metal peroxide ignition aid, binder, and any other components of the combustible heat source are combined to form a granular mixture by wet granulation.

[0184] The mixture can be formed into the desired shape using any suitable known ceramic forming method, such as, for example, slip casting, extrusion, injection molding, die compaction or pressing.

[0185] The mixture is preferably formed into the desired shape by pressing.

[0186] After formation, the desired shape is preferably dried to reduce its moisture content. The desired shape may be dried using any suitable known method. For example, the desired shape may be dried in an oven at a temperature of about 85 degrees Celsius to about 105 degrees Celsius.

[0187] The combustible heat source may be a non-blind combustible heat source.

[0188] As used herein in connection with the present invention, the term "non-blind" is used to describe a combustible heat source that includes at least one airflow channel extending along the length of the combustible heat source through which air may be drawn for inhalation by a user.

[0189] When the combustible heat source is a non-blind combustible heat source, a non-combustible, substantially impermeable barrier may be provided between the non-blind combustible heat source and the at least one airflow channel.

[0190] As used herein in connection with the present invention, the term "non-combustible barrier" is used to describe a barrier that is substantially non-combustible at temperatures reached by a combustible heat source during its ignition and combustion.

[0191] By including a non-combustible, substantially impermeable barrier between the non-blind combustible heat source and the at least one airflow channel, in use, combustion and decomposition products formed during ignition and combustion of the non-blind combustible heat source can advantageously be substantially prevented or inhibited from entering air drawn through the at least one airflow channel.

[0192] In use, the inclusion of a non-flammable, substantially impermeable barrier between the non-blind, combustible heat source and the at least one airflow channel can advantageously substantially prevent or inhibit activation of combustion of the non-blind, combustible heat source during a puff by a user. When used in an aerosol-generating article according to the present invention, this can advantageously substantially prevent or inhibit a spike in the temperature of the aerosol-forming substrate of the aerosol-generating article during a puff by a user.

[0193] The barrier between the non-blind combustible heat source and the at least one airflow channel may have a low thermal conductivity or a high thermal conductivity.

[0194] The thickness of the barrier between the non-blind combustible heat source and the at least one airflow channel can be selected to achieve good performance.

[0195] The barrier between the non-blind combustible heat source and the at least one airflow channel may be formed from one or more suitable materials that are substantially thermally stable and non-combustible at temperatures achieved by the non-blind combustible heat source during ignition and its combustion. Suitable materials are known in the art and include, but are not limited to, clays, metal oxides (such as iron oxide, alumina, titania, silica, silica-alumina, zirconia, and ceria), zeolites, zirconium phosphate, and other ceramic materials and combinations thereof.

[0196] The barrier between the non-blind combustible heat source and the at least one airflow channel may be glued or otherwise affixed to the inside surface of the at least one airflow channel of the non-blind combustible heat source.

[0197] Suitable methods for adhering or affixing a barrier to the inner surface of at least one airflow channel of a non-blind combustible heat source are known in the art and include, but are not limited to, methods described in U.S. Pat. No. 5,040,551 and WO 2009 / 074870 A2.

[0198] The barrier between the non-blind combustible heat source and the at least one airflow channel may comprise a liner inserted within the at least one airflow channel.

[0199] Preferably, the combustible heat source is a blind combustible heat source.

[0200] As used herein in connection with the present invention, the term "blind" is used to describe a combustible heat source that does not include any airflow channels extending along the length of the combustible heat source through which air may be drawn for inhalation by a user.

[0201] Blind combustible heat sources according to the present invention, and non-blind combustible heat sources according to the present invention, may include one or more closed or blocked channels through which air cannot be drawn for inhalation by a user.

[0202] For example, the combustible heat source may include one or more closed channels that extend only partway along the length of the combustible heat source.

[0203] The inclusion of one or more closed channels can increase the surface area of ​​the combustible heat source exposed to oxygen from the air, which can advantageously facilitate ignition and sustained combustion of the combustible heat source.

[0204] An aerosol-generating article according to the present invention comprises a combustible heat source according to the present invention and an aerosol-forming substrate.

[0205] The term "aerosol-forming substrate" as used herein in connection with the present invention is used to describe a substrate comprising an aerosol-forming material capable of releasing, upon heating, a volatile compound capable of forming an aerosol. The aerosol generated from an aerosol-forming substrate of an aerosol-generating article according to the present invention may or may not be visible and may comprise vapor (e.g., fine particles of a substance in a gaseous state, such as a substance that is normally liquid or solid at room temperature) and droplets of gas and condensed vapor.

[0206] The aerosol-forming substrate may be in the form of a plug or segment comprising a material capable of releasing a volatile compound in response to heating, which can be surrounded by a wrapper to form an aerosol. When the aerosol-forming substrate is in the form of such a plug or segment, the entire plug or segment, including the wrapper, is considered to be the aerosol-forming substrate.

[0207] The aerosol-forming substrate is downstream of the combustible heat source, i.e., the aerosol-forming substrate is between the combustible heat source and the distal end of the aerosol-generating article.

[0208] The aerosol-forming substrate may be in contact with a combustible heat source.

[0209] The aerosol-forming substrate may be longitudinally spaced from the combustible heat source.

[0210] Advantageously, the aerosol-forming substrate comprises an aerosol-forming material that includes an aerosol former.

[0211] The aerosol former may be any suitable compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and that is substantially resistant to thermal decomposition at the operating temperature of the aerosol-generating article. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, propylene glycol, 1,3-butanediol, and glycerin), 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).

[0212] Advantageously, the aerosol former comprises one or more polyhydric alcohols.

[0213] More advantageously, the aerosol former comprises glycerin.

[0214] The aerosol-forming substrate is preferably a solid aerosol-forming substrate. The aerosol-forming substrate may comprise both solid and liquid components.

[0215] The aerosol-forming substrate may comprise a plant-derived material.The aerosol-forming substrate may comprise a homogenized plant-derived material.

[0216] The aerosol-forming substrate may comprise nicotine.

[0217] The aerosol-forming substrate may comprise a tobacco material.

[0218] As used herein in connection with the present invention, the term "tobacco material" is used to describe any material containing tobacco, including, but not limited to, tobacco leaves, tobacco ribs, tobacco stems, tobacco trunks, tobacco dust, expanded tobacco, reconstituted tobacco material, and homogenized tobacco material.

[0219] The tobacco material may be in the form of, for example, powder, granules, pellets, shreds, threads, strips, sheets, or any combination thereof.

[0220] Advantageously, the aerosol-forming substrate comprises homogenized tobacco material.

[0221] As used herein in connection with the present invention, the term "homogenized tobacco material" is used to describe a material formed by agglomerating particulate tobacco.

[0222] In certain embodiments, the aerosol-forming substrate advantageously comprises a plurality of strands of homogenized tobacco material.

[0223] Advantageously, the multiple strands of homogenized tobacco material may be aligned substantially parallel to one another within the aerosol-forming substrate.

[0224] In certain embodiments, the aerosol-forming substrate advantageously comprises an assemblage of sheets of homogenized tobacco material.

[0225] The aerosol-forming substrate may comprise a rod comprising an assemblage of sheets of homogenized tobacco material.

[0226] As used herein in connection with the present invention, the term "rod" is used to describe a substantially cylindrical element of substantially circular, oval or elliptical cross section.

[0227] As used herein in connection with the present invention, the term "sheet" is used to describe a thin element having a width and length that is substantially greater than its thickness.

[0228] As used herein in connection with the present invention, the term "assembly" is used to describe a sheet that is rolled, folded, or otherwise compressed or contracted substantially transverse to the longitudinal axis of the aerosol-generating article.

[0229] The aerosol-forming substrate may include an aerosol-forming material and a wrapper surrounding and in contact with the aerosol-forming material.

[0230] The wrapper may be formed from any suitable sheet material that can be wrapped around the aerosol-forming material to form the aerosol-forming substrate.

[0231] In certain embodiments, the aerosol-forming substrate may include a rod including an assemblage of sheets of homogenized tobacco material and a wrapper surrounding and in contact with the tobacco material.

[0232] In certain embodiments, the aerosol-forming substrate advantageously comprises an assemblage of textured sheets of homogenized tobacco material.

[0233] As used herein in connection with the present invention, the term "textured sheet" is used to describe a sheet that has been crimped, embossed, debossed, perforated, or otherwise modified.

[0234] The use of textured sheets of homogenized tobacco material may advantageously facilitate assembling the homogenized tobacco material sheets to form the aerosol-forming substrate.

[0235] The aerosol-forming substrate may comprise an assembly of a textured sheet of homogenized tobacco material containing a plurality of spaced indentations, protrusions, perforations or any combination thereof.

[0236] The aerosol-forming substrate may comprise an assemblage of crimped sheets of homogenized tobacco material.

[0237] As used herein in connection with the present invention, the term "crimped sheet" is used to describe a sheet having a plurality of substantially parallel ridges or corrugations.

[0238] Advantageously, when an aerosol-generating article including the aerosol-forming substrate is assembled, the substantially parallel ridges or corrugations extend along or parallel to the longitudinal axis of the aerosol-generating article, which facilitates assembly of the crimped sheet of homogenized tobacco material to form the aerosol-forming substrate.

[0239] However, it will be appreciated that a crimped sheet of homogenized tobacco material for inclusion in an aerosol-forming substrate of an aerosol-generating article according to the present invention may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that are disposed at acute or obtuse angles to the longitudinal axis of the aerosol-generating article when the aerosol-generating article is assembled.

[0240] The aerosol-forming substrate is preferably substantially cylindrical.

[0241] The aerosol-forming substrate may have a length of from about 5 millimeters to about 20 millimeters.

[0242] The aerosol-forming substrate preferably has a length of from about 6 millimeters to about 15 millimeters.

[0243] More preferably, the aerosol-forming substrate has a length of from about 7 millimeters to about 12 millimeters.

[0244] The aerosol-forming substrate may have a diameter of from about 5 millimeters to about 15 millimeters.

[0245] The aerosol-forming substrate preferably has a diameter of about 5 millimeters to about 10 millimeters.

[0246] More preferably, the aerosol-forming substrate has a diameter of about 7 millimeters to about 8 millimeters.

[0247] An aerosol-generating article according to the present invention may comprise a combustible heat source according to the present invention, an aerosol-forming substrate downstream of the combustible heat source, and one or more other components.

[0248] The combustible heat source, the aerosol-forming substrate, and, if included, one or more other components of the aerosol-generating article may be assembled within one or more wrappers to form an elongated rod having a proximal end and an opposed distal end. Thus, an aerosol-generating article according to the present invention may resemble a conventional cigarette with a lighting end.

[0249] The one or more other components may include one or more of a cap, a moving or spacer element, an aerosol cooling element, or a heat exchanger and a mouthpiece.

[0250] An aerosol-generating article according to the present invention may include a cap configured to at least partially cover a front portion of the combustible heat source. The cap may be removable so that the front portion of the combustible heat source is exposed prior to use of the aerosol-generating article. Advantageously, the cap may protect the combustible heat source prior to use of the aerosol-generating article.

[0251] As used herein in connection with the present invention, the term "cap" is used to describe a protective cover at the distal end of an aerosol-generating article that substantially encloses the forward portion of the combustible heat source.

[0252] For example, an aerosol-generating article according to the present invention may include a removable cap attached to the distal end of the aerosol-generating article at a line of weakness, the cap comprising a cylindrical plug of material surrounded by a wrapper, as described in WO 2014 / 086998 A1.

[0253] The aerosol-generating article according to the present invention may comprise a moving or spacer element downstream of the aerosol-forming substrate, i.e. the moving or spacer element is located between the aerosol-forming substrate and the proximal end of the aerosol-generating article.

[0254] The moving element may abut the aerosol-forming substrate, or alternatively, the moving element may be longitudinally spaced from the aerosol-forming substrate.

[0255] The inclusion of a moving element may advantageously allow for cooling of the generated aerosol by heat transfer from the combustible heat source to the aerosol-forming substrate.

[0256] The inclusion of a moving element may advantageously allow the overall length of the aerosol-generating article to be adjusted to a desired value by appropriate selection of the length of the moving element, for example, the inclusion of a moving element may advantageously allow the overall length of the aerosol-generating article to be adjusted to a length similar to that of a conventional cigarette.

[0257] The moving element may have a length of about 7 millimeters to about 50 millimeters. For example, the moving element may have a length of about 10 millimeters to about 45 millimeters, or about 15 millimeters to about 30 millimeters.

[0258] The transfer element may have other lengths depending on the desired overall length of the aerosol-generating article and the presence and lengths of other components within the aerosol-generating article.

[0259] The transfer element may comprise an open-ended tubular hollow body. In use, air drawn into the aerosol-generating article by a user may pass through the open-ended tubular hollow body as it passes downstream through the aerosol-generating article from the aerosol-forming substrate to the proximal end of the aerosol-generating article.

[0260] The open-ended hollow tubular body may be formed from one or more materials that are substantially thermally stable at the temperature of the aerosol generated by the transfer of heat from a combustible heat source to the aerosol-forming substrate. Suitable materials are known in the art and include, but are not limited to, paper, cardboard, thermoplastics, cellulose acetate, and ceramics.

[0261] The aerosol-generating article according to the present invention may comprise an aerosol-cooling element or heat exchanger downstream of the aerosol-forming substrate, i.e., the aerosol-cooling element or heat exchanger is located between the aerosol-forming substrate and the proximal end of the aerosol-generating article.

[0262] The aerosol cooling element may advantageously cool the aerosol generated by heat transfer from a combustible heat source to an aerosol-forming substrate.

[0263] The aerosol cooling element may include a plurality of longitudinally extending channels.

[0264] The aerosol cooling element may comprise an assembly of sheets of material selected from the group consisting of metal foil, polymeric material, and substantially non-porous paper or cardboard.

[0265] The aerosol cooling element may comprise an assembly of sheets of 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.

[0266] The aerosol cooling element may comprise an assembly of sheets of biodegradable polymeric material such as polylactic acid (PLA) or Mater-Bi® grades (a commercially available family of starch-based copolyesters).

[0267] When the aerosol-generating article according to the invention comprises a moving element downstream of the aerosol-forming substrate and an aerosol-cooling element downstream of the aerosol-forming substrate, the aerosol-cooling element is preferably downstream of the moving element, i.e., the aerosol-cooling element is preferably located between the moving element and the proximal end of the aerosol-generating article.

[0268] An aerosol-generating article according to the present invention may comprise a mouthpiece downstream of the aerosol-forming substrate, i.e. the mouthpiece is located between the aerosol-forming substrate and the proximal end of the aerosol-generating article.

[0269] Aerosol-generating articles according to the present invention preferably include a mouthpiece located at the proximal end of the aerosol-generating article.

[0270] The mouthpiece may have low or very low filtering efficiency.

[0271] The mouthpiece may be a single segment mouthpiece.

[0272] The mouthpiece may be a multi-segment mouthpiece.

[0273] The mouthpiece may include one or more segments containing filtering material.

[0274] Suitable filter materials are well known in the art and include, but are not limited to, cellulose acetate and paper.

[0275] The mouthpiece may include one or more segments that include absorbent material.

[0276] The mouthpiece may include one or more segments that include absorbent material.

[0277] Suitable absorbent materials and suitable absorbent materials are known in the art and include, but are not limited to, activated carbon, silica gel, and zeolites.

[0278] Aerosol-generating articles according to the present invention may include one or more aerosol modifiers downstream of the aerosol-forming substrate. For example, if included, one or more of the mouthpiece, transfer element, and aerosol-cooling element of an aerosol-generating article according to the present invention may include one or more aerosol modifiers.

[0279] As used herein in connection with the present invention, the term "aerosol modifier" is used to describe any agent that, when used, modifies one or more characteristics or properties of the aerosol generated by the aerosol-forming substrate of the aerosol-generating article.

[0280] Suitable aerosol modifiers include, but are not limited to, flavoring agents, and chemosensory agents.

[0281] As used herein in connection with the present invention, the term "chemosensory agent" is used to describe an agent that, when used, is perceived in the oral or nasal cavity of a user by means other than, or in addition to, perception via taste or olfactory receptor cells. Perception of chemosensory agents is typically via a "trigeminal response" (either the trigeminal nerve, glossopharyngeal nerve, vagus nerve, or some combination thereof). Chemosensory agents are typically perceived as having a hot, savory, cooling, or calming sensation.

[0282] Aerosol-generating articles according to the present invention may include one or more aerosol modifiers downstream of the aerosol-forming substrate that are both flavorants and chemosensory agents. For example, if included, one or more of the mouthpiece, transfer element, and aerosol-cooling element of an aerosol-generating article according to the present invention may include menthol or another flavorant that provides a cooling chemosensory effect.

[0283] Aerosol-generating articles according to the present invention may further comprise one or more thermally conductive elements.

[0284] Preferably, the aerosol-generating article according to the invention comprises a thermally conductive element around at least a portion of the aerosol-forming substrate, the thermally conductive element being advantageously capable of transferring heat to the periphery of the aerosol-forming substrate by conduction.

[0285] More preferably, the aerosol-generating article according to the invention comprises a thermally conductive element surrounding and in contact with at least a portion of the aerosol-forming substrate, which may advantageously facilitate conductive heat transfer to the periphery of the aerosol-forming substrate.

[0286] The thermally conductive element may be around the entire length of the aerosol-forming substrate, i.e. the thermally conductive element may be on the entire length of the aerosol-forming substrate.

[0287] Preferably, the thermally conductive element is not around the rear portion of the aerosol-forming substrate, i.e. the aerosol-forming substrate advantageously extends longitudinally in the downstream direction beyond the thermally conductive element.

[0288] Preferably, the aerosol-forming substrate extends longitudinally in a downstream direction beyond the thermally conductive element for at least about 3 millimeters.

[0289] Preferably, an aerosol-generating article according to the present invention comprises a thermally conductive element around at least a portion of the combustible heat source and around at least a portion of the aerosol-forming substrate.

[0290] More preferably, an aerosol-generating article according to the present invention comprises a heat-conductive element around at least a rear portion of the combustible heat source and around at least a front portion of the aerosol-forming substrate.

[0291] Most preferably, an aerosol-generating article according to the present invention comprises a thermally conductive element around and in contact with at least a rear portion of the combustible heat source and around and in contact with at least a front portion of the aerosol-forming substrate.

[0292] The thermally conductive element may provide a thermal link between the combustible heat source of the aerosol-generating article and the aerosol-forming substrate, which may advantageously help promote adequate heat transfer from the combustible heat source to the aerosol-forming substrate to produce an acceptable aerosol.

[0293] The rear portion of the heat source in contact with the thermally conductive element is preferably between about 2 millimeters and about 8 millimeters in length.

[0294] More preferably, the rear portion of the heat source in contact with the thermally conductive element is between about 3 millimeters and about 5 millimeters in length.

[0295] The thermally conductive element is preferably non-flammable.

[0296] The thermally conductive element may be oxygen-restrictive, in other words, the thermally conductive element may inhibit or prevent the passage of oxygen through the thermally conductive element.

[0297] The thermally conductive element may be formed from any suitable thermally conductive material or combination of materials.

[0298] The thermally conductive element preferably comprises one or more thermally conductive materials having a bulk thermal conductivity of between about 10 Watts per meter per Kelvin (W / (m·K)) and about 500 Watts per meter per Kelvin (W / (m·K)) at 23 degrees Celsius and 50 percent relative humidity, as measured using the Modified Transient Plane Source (MTPS) method, and between about 15 Watts per meter per Kelvin (W / (m·K)) and about 400 Watts per meter per Kelvin (W / (m·K)).

[0299] Advantageously, the thermally conductive element comprises one or more metals, one or more alloys, or a combination of one or more metals and one or more alloys.

[0300] Suitable thermally conductive materials are well known in the art and include, but are not limited to, metal foils such as aluminum foil, iron foil and copper foil, and alloy foils such as steel foil.

[0301] Advantageously, the thermally conductive element comprises aluminium foil.

[0302] Aerosol-generating articles according to the present invention may comprise a non-flammable, substantially impermeable barrier between the rear end face of the combustible heat source and the aerosol-forming substrate.

[0303] By including a non-flammable, substantially impermeable barrier between the rear end face of the combustible heat source and the aerosol-forming substrate, the temperature to which the aerosol-forming substrate is exposed during ignition and combustion of the combustible heat source may be advantageously reduced, which may help to avoid or reduce thermal decomposition or combustion of the aerosol-forming substrate during use of the aerosol-generating article.

[0304] By including a non-flammable, substantially impermeable barrier between the rear end face of the combustible heat source and the aerosol-forming substrate, migration of components of the aerosol-forming substrate towards the combustible heat source can advantageously be substantially prevented or inhibited during storage and use of the aerosol-generating article.

[0305] The barrier may be adjacent to one or both of the rear end face of the combustible heat source and the aerosol-forming substrate, or the barrier may be longitudinally spaced from one or both of the rear end face of the combustible heat source and the aerosol-forming substrate.

[0306] Advantageously, the barrier is glued or otherwise affixed to the rear end face of the combustible heat source.

[0307] Suitable methods for adhering or affixing a barrier to the rear end face of a combustible heat source are known in the art and include, but are not limited to, spray painting, vapor deposition, dipping, material transfer (e.g., brushing or gluing), electrostatic deposition, or any combination thereof.

[0308] The barrier between the back end face of the combustible heat source and the aerosol-forming substrate may have a low or high thermal conductivity. For example, the barrier may be formed from a material with a bulk thermal conductivity of about 0.1 Watts per meter Kelvin (W / (m·K)) to about 200 Watts per meter Kelvin (W / (m·K)) at 23 degrees Celsius and 50 percent relative humidity when measured using the modified transient plane heat source (MTPS) method.

[0309] The thickness of the barrier between the back face of the combustible heat source and the aerosol-forming substrate can be selected to achieve good performance, for example, the thickness of the barrier can be from about 10 micrometers to about 500 micrometers.

[0310] The barrier between the back end face of the combustible heat source and the aerosol-forming substrate may be formed from one or more suitable materials that are substantially thermally stable and non-flammable at temperatures reached by the combustible heat source during ignition and combustion. Suitable materials are known in the art and include, but are not limited to, clays (such as, for example, bentonite and kaolinite), glasses, minerals, ceramic materials, resins, metals, or any combination thereof.

[0311] Preferably, the barrier comprises aluminum foil.

[0312] The aluminum foil barrier may be applied to the rear end face of the combustible heat source by gluing or pressing it onto the combustible heat source. The barrier may be cut or otherwise machined so that the aluminum foil covers and adheres to at least substantially the entire rear end face of the combustible heat source. Advantageously, the aluminum foil covers and adheres to the entire rear end face of the combustible heat source.

[0313] An aerosol-generating article according to the present invention may comprise a non-blind combustible heat source according to the present invention.

[0314] Where the combustible heat source is a non-blind combustible heat source, in use, air drawn through the aerosol-generating article for inhalation by a user passes through at least one airflow channel along the length of the combustible heat source.

[0315] When the combustible heat source is a non-blind combustible heat source, heating of the aerosol-forming substrate occurs by conduction and forced convection.

[0316] When an aerosol-generating article according to the present invention comprises a non-blind combustible heat source according to the present invention and a non-combustible, substantially non-permeable barrier between the rear end face of the combustible heat source and the aerosol-forming substrate, the barrier should allow air drawn through at least one airflow channel extending along the length of the combustible heat source to be drawn downstream through the aerosol-generating article.

[0317] Aerosol-generating articles according to the present invention preferably include a blind combustible heat source according to the present invention.

[0318] If the combustible heat source is a blind combustible heat source, then in use, air drawn through the aerosol-generating article for inhalation by a user does not pass through any airflow channels along the length of the blind combustible heat source.

[0319] If the combustible heat source is a blind combustible heat source, heating of the aerosol-forming substrate occurs primarily by conduction and heating of the aerosol-forming substrate by forced convection is minimized or reduced. In such embodiments, it is particularly important to optimize conductive heat transfer between the combustible heat source and the aerosol-forming substrate.

[0320] The lack of any airflow channels extending along the length of the combustible heat source through which air may be drawn for inhalation by the user can advantageously substantially prevent or inhibit activation of combustion of the blind combustible heat source during a puff by the user, which can advantageously substantially prevent or inhibit spikes in the temperature of the aerosol-forming substrate while the user is smoking.

[0321] By preventing or inhibiting activation of combustion of blind combustible heat sources and thus preventing or inhibiting excessive temperature rise in the aerosol-forming substrate, combustion or thermal decomposition of the aerosol-forming substrate under heavy puffing conditions can be advantageously avoided. Additionally, the impact of the user's puffing conditions on the composition of the mainstream aerosol can be advantageously minimized or reduced.

[0322] The inclusion of a blind combustible heat source can advantageously substantially prevent or inhibit combustion and decomposition products and other materials formed during ignition and combustion of the blind combustible heat source from entering the air drawn through the aerosol-generating article for inhalation by the user.

[0323] When the combustible heat source is a blind combustible heat source, the aerosol-generating article according to the present invention includes one or more air intakes downstream of the blind combustible heat source that draw air into the aerosol-generating article for inhalation by a user.

[0324] In such an embodiment, air drawn through the aerosol-generating article for inhalation by a user enters the aerosol-generating article through one or more air inlets rather than through the distal end of the aerosol-generating article.

[0325] Where the combustible heat source is a non-blind combustible heat source, the aerosol-generating article according to the present invention may also include one or more air intake ports downstream of the non-blind combustible heat source for drawing air into the aerosol-generating article for inhalation by a user.

[0326] Aerosol-generating articles according to the present invention may comprise one or more primary air inlets around the periphery of the aerosol-forming substrate.

[0327] In such embodiments, during a puff by the user, cool air is drawn into the aerosol-forming substrate of the aerosol-generating article through one or more air inlets around the periphery of the aerosol-forming substrate, which may advantageously reduce the temperature of the aerosol-forming substrate during a puff by the user, thereby substantially preventing or inhibiting spikes in the temperature of the aerosol-forming substrate.

[0328] As used herein in connection with the present invention, the term "cool air" is used to describe ambient air that is not significantly heated by a combustible heat source during puffing by a user.

[0329] By preventing or arresting spikes in the temperature of the aerosol-forming substrate, the inclusion of one or more air inlets around the periphery of the aerosol-forming substrate can advantageously help to avoid or reduce combustion or thermal decomposition of the aerosol-forming substrate under heavy smoking conditions.

[0330] By including one or more air inlets around the periphery of the aerosol-forming substrate, the effect of the user's puffing conditions on the composition of the mainstream aerosol of the aerosol-generating article may be advantageously minimized or reduced.

[0331] In certain preferred embodiments, aerosol-generating articles according to the present invention may comprise one or more air inlets located adjacent the downstream end of the aerosol-forming substrate.

[0332] Aerosol-generating articles according to the present invention may have any desired length.

[0333] Aerosol-generating articles according to the present invention may preferably have an overall length of from about 65 millimeters to about 100 millimeters.

[0334] Aerosol-generating articles according to the present invention may have any desired width.

[0335] Aerosol-generating articles according to the present invention may preferably have a width of from about 5 millimeters to about 12 millimeters.

[0336] Aerosol-generating articles according to the present invention may be assembled using known methods and machinery.

[0337] For the avoidance of doubt, where applicable, the features described above for combustible heat sources according to the present invention may also apply to aerosol-generating articles according to the present invention, and vice versa.

[0338] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0339] [Figure 1] FIG. 1 shows a schematic longitudinal cross-section of an aerosol-generating article according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a graph of calcium peroxide content as a function of time for a combustible heat source according to an embodiment of the present invention and a comparative combustible heat source not according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0340] An aerosol-generating article 2 according to an embodiment of the present invention shown in Figure 1 comprises a combustible heat source 4 according to the present invention and an aerosol-forming substrate 10 downstream of the combustible heat source 4. The combustible heat source 4 is a blind combustible heat source having a front end surface 6 and an opposite rear end surface 8, and is located at the distal end of the aerosol-generating article 2. The aerosol-generating article 2 further comprises a moving element 12, an aerosol-cooling element 14, a spacer element 16, and a mouthpiece 18. The combustible heat source 4, the aerosol-forming substrate 10, the moving element 12, the aerosol-cooling element 14, the spacer element 16, and the mouthpiece 18 are arranged in abutting, coaxial alignment. As shown in Figure 1, the aerosol-forming substrate 10, the moving element 12, the aerosol-cooling element 14, the spacer element 16, and the mouthpiece 18, as well as the rear portion of the blind combustible heat source 4, are wrapped in an outer wrapper 20 of a sheet material, such as cigarette paper.

[0341] 1, a non-combustible, substantially impermeable barrier 22 in the form of an aluminum foil disk is provided between the trailing end surface 8 of the combustible heat source 4 and the aerosol-forming substrate 10. The barrier 22 is applied to the trailing end surface 8 of the combustible carbonaceous heat source 4 by pressing the aluminum foil disk onto the trailing end surface 8 of the combustible heat source 4 so that it abuts the trailing end surface 8 of the combustible carbonaceous heat source 4 and the aerosol-forming substrate 10.

[0342] Combustible heat source 4 comprises carbon, an alkaline earth metal peroxide ignition aid, and a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose.

[0343] The aerosol-forming substrate 10 is located immediately downstream of a barrier 22 applied to the rear end surface 8 of the combustible heat source 4. The aerosol-forming substrate 10 includes a collection 24 of crimped sheets of homogenized tobacco material and a wrapper 26 surrounding and in direct contact with the collection 24 of crimped sheets of homogenized tobacco material. The collection 24 of crimped sheets of homogenized tobacco material includes a suitable aerosol former, such as, for example, glycerin.

[0344] The transfer element 12 is located immediately downstream of the aerosol-forming substrate 10 and comprises a cylindrical, open-ended, hollow cellulose acetate tube 28 .

[0345] The aerosol cooling element 14 is located immediately downstream of the moving element 12 and comprises an assembly of sheets of a biodegradable polymeric material, such as polylactic acid.

[0346] Spacer element 16 is located immediately downstream of aerosol cooling element 14 and comprises a cylindrical, open-ended, hollow paper or cardboard tube.

[0347] Mouthpiece 18 is located immediately downstream of spacer element 16. As shown in Figure 1, mouthpiece 18 is located at the proximal end of aerosol-generating article 2 and includes a cylindrical plug 30 of suitable filtration material, such as very low filtration efficiency cellulose acetate tow, encased in a filter plug wrap 32.

[0348] The aerosol-generating article may further include a band of tipping paper (not shown) surrounding the downstream end portion of the outer wrapper 20 .

[0349] As shown in FIG. 1 , the aerosol-generating article 2 further comprises a thermally conductive element 34 formed from a suitable thermally conductive material, such as aluminum foil, that surrounds and is in direct contact with the rear portion 4 b of the combustible heat source 4 and the front portion 10 a of the aerosol-forming substrate 10. In the aerosol-generating article 2 according to the embodiment of the present invention shown in FIG. 1 , the aerosol-forming substrate 10 extends downstream beyond the thermally conductive element 34. That is, the thermally conductive element 34 does not surround and is not in contact with the rear portion of the aerosol-forming substrate 10. However, it will be appreciated that in other embodiments of the present invention (not shown), the thermally conductive element 34 may surround and be in contact with the entire length of the aerosol-forming substrate 10. It will be appreciated that in other embodiments of the present invention (not shown), one or more additional thermally conductive elements may also be provided on top of the thermally conductive element 34.

[0350] The aerosol-generating article 2 according to the embodiment of the invention shown in Figure 1 comprises one or more air inlet openings 36 around the periphery of the aerosol-forming substrate 10. As shown in Figure 1, a circumferential arrangement of air inlet openings 36 is provided in the wrapper 26 and overlying outer wrapper 20 of the aerosol-forming substrate 10 to allow cool air (indicated by the dotted arrows in Figure 1) to enter the aerosol-forming substrate 10.

[0351] In use, a user ignites the combustible carbonaceous heat source 4. Once the combustible carbonaceous heat source 4 is ignited, the user draws air into the mouthpiece 18 of the aerosol-generating article 2. As the user draws air into the mouthpiece 18, cool air (indicated by the dotted arrow in FIG. 1 ) is drawn through the air inlet 36 and into the aerosol-forming substrate 10 of the aerosol-generating article 2.

[0352] The periphery of the front portion 10 a of the aerosol-forming substrate 10 is heated by conduction through the rear end face 8 of the combustible heat source 4 and the barrier 22 , and through the thermally conductive element 34 .

[0353] Heating of the aerosol-forming substrate 10 by conduction releases aerosol formers and other volatile and semi-volatile compounds from the assembly of crimped sheets of homogenized tobacco material 24. As the compounds released from the aerosol-forming substrate 10 flow through the aerosol-forming substrate 10, they form an aerosol that is entrained in air drawn into the aerosol-forming substrate 10 of the aerosol-generating article 2 through the air inlet 36. The drawn-in air and entrained aerosol (indicated by dashed arrows in FIG. 1 ) pass downstream through the cylindrical, open-ended, hollow cellulose acetate tube 28 of the transfer element 12, the aerosol cooling element 14, and the spacer element 16, where they cool and condense. The cooled drawn-in air and entrained aerosol flow downstream through the mouthpiece 18 and are delivered to the user through the proximal end of the aerosol-generating article 2. A non-combustible, substantially impermeable barrier 22 on the rear end face 8 of the combustible carbonaceous heat source 4 isolates the combustible heat source 4 from air drawn through the aerosol-generating article 2 so that, in use, the air drawn through the aerosol-generating article 2 does not come into direct contact with the combustible heat source 4.

[0354] The specific embodiments and examples described above illustrate but do not limit the invention, and it is understood that other embodiments of the invention may be made and that the specific embodiments and examples described herein are not exhaustive.

[0355] A combustible heat source according to the present invention was produced having the composition shown in Table 1. [Table 1]

[0356] The components in Table 1 were combined and wet granulated to form a granular mixture. Charcoal, calcium peroxide, and carboxymethyl cellulose were mixed to form a granular mixture. The granular mixture of charcoal, calcium peroxide, and carboxymethyl cellulose was air fluidized and sprayed with a liquid solution of potassium tricitrate hydrate and an aqueous solution of hydroxypropyl cellulose to form a granular mixture.

[0357] The granular mixture is formed into a cylindrical shape by pressing. Approximately 400 milligrams of the granular mixture is pressed into a single-cavity press to produce a cylindrical combustible heat source having a length of approximately 9 millimeters, a width of approximately 7.7 millimeters, and a density of approximately 0.9 grams per cubic centimeter. The cylindrical combustible heat source is removed from the single-cavity press and dried in a drying oven at a temperature of approximately 85 degrees Celsius to approximately 105 degrees Celsius for approximately 3 hours.

[0358] Comparative combustible heat sources not according to the present invention were also produced having the compositions shown in columns A, B, and C of Table 2. [Table 2]

[0359] The components in Table 2 were combined and wet granulated to form a granular mixture. Charcoal, calcium peroxide, and carboxymethyl cellulose were mixed to form a granular mixture. The granular mixture of charcoal, calcium peroxide, and carboxymethyl cellulose was air fluidized and sprayed with a liquid solution of potassium tricitrate hydrate and an aqueous solution of bentonite to form a granular mixture.

[0360] The granular mixture is formed into a cylindrical shape by pressing. Approximately 400 milligrams of the granular mixture is pressed into a single cavity press to produce a cylindrical combustible heat source having a length of approximately 9 millimeters, a width of approximately 7.7 millimeters, and a density of approximately 0.9 grams per cubic centimeter. The cylindrical combustible heat source is removed from the single cavity press and placed in a drying oven at a temperature of approximately 85 degrees Celsius to approximately 105 degrees Celsius for approximately 3 hours.

[0361] To simulate environmental conditions to which a flammable heat source may be exposed during shipping and storage, a flammable heat source according to the present invention and a comparative flammable heat source not according to the present invention are conditioned to approximately 30 degrees Celsius and approximately 75 percent relative humidity for seven days. The calcium peroxide content (weight percent) of the flammable heat source according to the present invention and the comparative flammable heat source not according to the present invention is measured as a function of time by titration with potassium permanganate (KMnO) solution. The results are shown in Figure 2. The upper line labeled I in Figure 2 shows the measured calcium peroxide content of the flammable heat source according to the present invention as a function of time, and the lower lines labeled A, B, and C in Figure 2 show the measured calcium peroxide content of the comparative flammable heat source not according to the present invention as a function of time. The values ​​shown in Figures 2 and 3 are the average of measurements of three replicates of each flammable heat source.

[0362] As shown in FIG. 2, the decomposition rate of calcium peroxide over time in a combustible heat source according to the present invention is advantageously significantly lower than the decomposition rate of calcium peroxide over time in a comparative combustible heat source not according to the present invention.

[0363] The ignition propagation speeds of ten flammable heat sources according to the present invention and ten comparative flammable heat sources not according to the present invention, having the compositions shown in column A of Table 2, were also measured. The results are shown in Table 3. The flammable heat sources according to the present invention and the comparative flammable heat sources not according to the present invention were conditioned for about 24 hours at about 22 degrees Celsius and about 50 percent relative humidity before measuring the ignition propagation speeds. To measure the ignition propagation speeds, thermocouples were inserted into the flammable heat sources according to the present invention and the comparative flammable heat sources not according to the present invention at two locations: a first location 1 millimeter from the front end face of the flammable heat source and a second location 8 millimeters from the front end face of the flammable heat source. The front end faces of the flammable heat sources according to the present invention and the comparative flammable heat sources not according to the present invention were ignited using an electric lighter. The difference in the time it takes to reach about 350 degrees Celsius, as measured by the thermocouples at the first and second locations, was measured. The ignition propagation times shown in Table 3 are the average times measured for ten combustible heat sources according to the invention and ten comparative combustible heat sources not according to the invention. [Table 3]

[0364] As shown in Table 3, the ignition propagation times of combustible heat sources according to the present invention are advantageously significantly shorter than the ignition propagation times of comparative combustible heat sources not according to the present invention.

[0365] The results in Figure 2 and Table 3 demonstrate the improved chemical and physical stability and combustion characteristics of the combustible heat source according to the present invention due to the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether.

[0366] The results in Figure 2 demonstrate that including a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in a combustible heat source according to the present invention advantageously significantly reduces the decomposition of the alkaline earth metal peroxide ignition aid as a result of exposure to environmental conditions. In particular, the results in Figure 2 demonstrate that including a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in a combustible heat source according to the present invention advantageously significantly reduces the decomposition of the alkaline earth metal peroxide ignition aid as a result of exposure to high humidity.

[0367] The results in Table 3 also demonstrate that the inclusion of a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether in a combustible heat source according to the present invention advantageously significantly improves the ignition propagation rate of the combustible heat source according to the present invention.

Claims

1. 1. A combustible heat source for an aerosol-generating article, said combustible heat source comprising: Carbon and an alkaline earth metal peroxide ignition aid; a binder comprising a combination of carboxymethyl cellulose and at least one additional cellulose ether selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose; the combustible heat source comprises carboxymethyl cellulose in an amount of at least 1.5 weight percent and at least 0.2 weight percent of the at least one additional cellulose ether; the ratio of the weight percent of the carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source is at least 1:1; Flammable heat source.

2. 10. The combustible heat source of claim 1, wherein the at least one additional cellulose ether is hydroxypropyl cellulose.

3. 3. The combustible heat source of claim 1, wherein the ratio of the weight percent of carboxymethyl cellulose to the weight percent of the at least one additional cellulose ether in the combustible heat source is from 2:1 to 4:

1.

4. The combustible heat source according to any one of claims 1 to 3, wherein the alkaline earth metal peroxide ignition aid is calcium peroxide.

5. The combustible heat source of any one of claims 1 to 4, wherein the combustible heat source comprises at least 15 weight percent of the alkaline earth metal peroxide ignition aid.

6. The combustible heat source of any one of claims 1 to 5, wherein the combustible heat source comprises 20 to 60 percent by weight of the alkaline earth metal peroxide ignition aid.

7. The combustible heat source of any one of claims 1 to 6, wherein the combustible heat source comprises at least 3 weight percent of the binder.

8. The combustible heat source of any one of claims 1 to 7, wherein the combustible heat source comprises 4 to 15 percent by weight of the binder.

9. The combustible heat source of any one of claims 1 to 8, wherein the combustible heat source comprises 0.75 weight percent to 5 weight percent of the at least one additional cellulose ether.

10. A combustible heat source described in any one of claims 1 to 9, wherein the combustible heat source comprises at least 1 weight percent of the at least one additional cellulose ether.

11. A combustible heat source described in any one of claims 1 to 10, wherein the combustible heat source comprises at least 3 weight percent of the at least one additional cellulose ether.

12. 12. The combustible heat source of any one of claims 1 to 11, wherein the combustible heat source comprises at least 25 weight percent carbon.

13. 13. The combustible heat source of any one of claims 1 to 12, wherein the combustible heat source comprises 30 to 55 percent by weight of carbon.

14. 14. The combustible heat source of claim 1, further comprising one or more carboxylic acid combustion salts.

15. A combustible heat source as described in any one of claims 1 to 11, wherein the binder does not contain a non-flammable inorganic silicate binder.

16. An aerosol-generating article comprising: A combustible heat source according to any one of claims 1 to 15; an aerosol-forming substrate downstream of the combustible heat source.

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