Aerosol-generating article having a wrapper to reduce crystallization

Abstract

The present invention relates to an aerosol-generating article. The aerosol-generating article comprises an aerosol-forming substrate having a pH value of less than 5 and containing an aerosol former content of at least 5 weight percent on a dry weight basis. The aerosol-generating article comprises a wrapper at least partially enclosing the aerosol-forming substrate. The wrapper has a calcium carbonate content of less than 45 weight percent. The present invention also relates to an aerosol-generating system.

Description

[Technical Field]

[0001] The present disclosure relates to aerosol-generating articles. The present disclosure further relates to aerosol-generating systems. [Background technology]

[0002] It is known to provide aerosol-generating devices for producing inhalable vapors. Such devices may heat an aerosol-forming substrate contained in an aerosol-generating article without burning the aerosol-forming substrate. The aerosol-generating article may have a rod shape for insertion into a heating chamber of the aerosol-generating device.

[0003] The aerosol-generating device may include a heating arrangement. The heating arrangement may include one or more resistive heating elements. The heating arrangement may be an induction heating arrangement and may include an induction coil configured to inductively heat the susceptor. The susceptor may be part of the device or part of the aerosol-generating article.

[0004] Aerosol-generating articles are known in the art in which an aerosol-generating substrate is provided in the form of a gel or film containing nicotine. It is also known that the inclusion of an acid in such a substrate advantageously enables the production of inhalable aerosols with improved sensory properties. The inclusion of an acid in such a substrate may advantageously enable the production of inhalable aerosols that provide an improved nicotine satisfaction to the user.

[0005] However, it has been observed that aerosol-generating substrates containing acids, e.g., organic acids such as lactic acid and fumaric acid, tend to form deposits on the outer surface of the wrapper of the aerosol-generating article, especially when the wrapper surrounds the aerosol-forming substrate. It has been observed that the formation of such deposits can be particularly severe when the aerosol-generating article is stored in a high temperature environment, a high humidity environment, or both. The formation of deposits on the outer surface of the wrapper can adversely affect the visual appearance of the article. The formation of deposits on the outer surface of the wrapper can adversely affect the stability of nicotine in the aerosol-forming substrate of the article. The formation of deposits on the outer surface of the wrapper over time can adversely affect the shelf life of the article.

[0006] It would be desirable to provide an aerosol-generating article that reduces or prevents the formation of deposits on the exterior surface of the aerosol-generating article, particularly when the aerosol-generating substrate within the aerosol-generating article comprises an acid. Summary of the Invention

[0007] According to an embodiment of the present invention, there is provided an aerosol-generating article. The aerosol-generating article may include an aerosol-forming substrate. The aerosol-forming substrate may have a pH value of less than 5. The aerosol-forming substrate may have an aerosol former content of at least 5 weight percent on a dry weight basis. The aerosol-generating article may include a wrapper at least partially enclosing the aerosol-forming substrate. The wrapper may have a calcium carbonate content of less than 45 weight percent.

[0008] According to an embodiment of the present invention, there is provided an aerosol-generating article. The aerosol-generating article comprises an aerosol-forming substrate. The aerosol-forming substrate has a pH value of less than 5. The aerosol-forming substrate has an aerosol former content of at least 5 weight percent on a dry weight basis. The aerosol-generating article comprises a wrapper at least partially enclosing the aerosol-forming substrate. The wrapper has a calcium carbonate content of less than 45 weight percent.

[0009] An aerosol-generating article is provided that has reduced or no deposit formation on an outer wrapper surrounding an aerosol-generating substrate. An aerosol-generating article may be provided that has reduced change in visual appearance over time. An aerosol-generating article may be provided that has improved nicotine stability. An aerosol-generating article may be provided that has an extended shelf life.

[0010] Without wishing to be bound by theory, it is believed that the formation of deposits on the outer surface of the wrapper is caused by crystals that form when acid from the aerosol-forming substrate contacts and reacts with the wrapper that surrounds the aerosol-forming substrate and contains a large amount of filler material (especially if the filler material contains calcium carbonate). For example, if lactic acid is used in the aerosol-forming substrate, the crystals may be made from calcium lactate. For example, if fumaric acid is used in the aerosol-forming substrate, the crystals may be made from calcium fumarate.

[0011] As used herein, the term "filler material" generally refers to materials known to those skilled in the art to be suitable for use as filler materials in the paper industry. Filler materials are generally water-insoluble particulate materials in the size range of about 0.1 to 10 μm that are added to a slurry of cellulose fibers prior to paper formation. Typical filter materials may be China clay, calcium carbonate, talc, titanium dioxide, starch, calcium sulfate, gypsum (calcium sulfate dihydrate), barium sulfate, magnesium carbonate, bentonite, aluminum hydroxide (hydrated alumina), silicate minerals such as silica and silicate pigments, and niacin pigments.

[0012] The wrapper may have a calcium carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent. The calcium carbonate content may be based on the total weight of the wrapper. The wrapper may be calcium carbonate-free.

[0013] The combined calcium carbonate and magnesium carbonate content in the wrapper may be less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent. The combined calcium carbonate and magnesium carbonate content may be based on the total weight of the wrapper. The wrapper may be free of calcium carbonate and magnesium carbonate.

[0014] The wrapper may have an alkali metal carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent. The alkali metal carbonate content may be based on the total weight of the wrapper. The wrapper may be free of alkali metal carbonate.

[0015] The wrapper may have a metal carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent. The metal carbonate content may be based on the total weight of the wrapper. The wrapper may be free of metal carbonate.

[0016] The wrapper may have a total content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent of one or more filler materials selected from china clay, calcium carbonate, talc, titanium dioxide, starch, calcium sulfate, gypsum (calcium sulfate dihydrate), barium sulfate, magnesium carbonate, bentonite, aluminum hydroxide (hydrated alumina), silicate minerals such as silica and silicate pigments, and zinc pigments. The wrapper may be free of filler materials selected from china clay, calcium carbonate, talc, titanium dioxide, starch, calcium sulfate, gypsum (calcium sulfate dihydrate), barium sulfate, magnesium carbonate, bentonite, aluminum hydroxide (hydrated alumina), silicate minerals such as silica and silicate pigments, and zinc pigments.

[0017] The wrapper may have a total filler material content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent. The total filler material content may be based on the total weight of the wrapper. The wrapper may be free of filler material.

[0018] The ratio of weight percentage of calcium carbonate to other fillers in the wrapper may be 0-10, preferably 0-1, more preferably 0-0.5, more preferably 0-0.3, more preferably 0-0.2, more preferably 0-0.1.

[0019] The ratio of calcium carbonate to titanium dioxide contained in the wrapper may be 0-10, preferably 0-1, more preferably 0-0.5, more preferably 0-0.3, more preferably 0-0.2, more preferably 0-0.1.

[0020] The wrapper may include one or more fillers other than calcium carbonate, and the sum of the weight percentages of the one or more fillers other than calcium carbonate in the wrapper may be at least equal to the weight percentage of calcium carbonate in the wrapper.

[0021] The wrapper may include titanium dioxide, and the weight percentage of titanium dioxide in the wrapper may be at least equal to the weight percentage of calcium carbonate in the wrapper.

[0022] The wrapper may include both titanium dioxide and calcium carbonate. The wrapper may include titanium dioxide and no calcium carbonate.

[0023] The wrapper may comprise at least 5 weight percent titanium dioxide, preferably at least 10 weight percent, more preferably at least 15 weight percent, more preferably at least 20 weight percent, more preferably at least 25 weight percent, more preferably at least 30 weight percent, more preferably at least 35 weight percent, and more preferably at least 40 weight percent titanium dioxide. The titanium dioxide content may be based on the total weight of the wrapper.

[0024] The wrapper may comprise at least 70 weight percent, preferably at least 75 weight percent, more preferably at least 80 weight percent, more preferably at least 85 weight percent, more preferably at least 90 weight percent, more preferably at least 95 weight percent, more preferably at least 97 weight percent, more preferably at least 98 weight percent, more preferably at least 99 weight percent, and more preferably at least 99.5 weight percent cellulose fibers.

[0025] The wrapper may comprise at least 70 weight percent, preferably at least 75 weight percent, more preferably at least 80 weight percent, more preferably at least 85 weight percent, more preferably at least 90 weight percent, more preferably at least 95 weight percent, more preferably at least 97 weight percent, more preferably at least 98 weight percent, more preferably at least 99 weight percent, and more preferably at least 99.5 weight percent cellulose fiber on a dry weight basis. The cellulose fiber content may be based on the total weight of the wrapper.

[0026] The wrapper at least partially surrounding the aerosol-forming substrate and containing less than 45 weight percent calcium carbonate may be a tipping wrapper surrounding multiple components of the article, including the portion containing the aerosol-forming substrate. The tipping wrapper, or at least a portion thereof, may form the outermost layer of the aerosol-generating article.

[0027] The wrapper at least partially surrounding the aerosol-forming substrate and containing less than 45 percent by weight of calcium carbonate may be a single-component wrapper surrounding only the aerosol-forming substrate.

[0028] The basis weight of the wrapper may be from 30 grams per square meter to 100 grams per square meter, preferably from 50 grams per square meter to 90 grams per square meter, and more preferably from 60 grams per square meter to 80 grams per square meter.

[0029] The thickness of the wrapper may be from 50 micrometers to 90 micrometers, preferably from 60 micrometers to 80 micrometers, and more preferably from 65 micrometers to 75 micrometers.

[0030] The wrapper may have a basis weight of 55 grams per square meter to 65 grams per square meter, a thickness of 65 micrometers to 75 micrometers, and optionally, the wrapper may be free of fillers.

[0031] The wrapper may exhibit a wrapper permeability of less than 100 Coresta units, less than 80 Coresta units, less than 50 Coresta units, less than 40 Coresta units, or less than 30 Coresta units. The wrapper may exhibit a wrapper permeability of less than 20 Coresta units, less than 10 Coresta units, less than 8 Coresta units, less than 6 Coresta units, or less than 5 Coresta units. The wrapper may exhibit a wrapper permeability of 1 to 10 Coresta units, preferably 1 to 5 Coresta units, more preferably 2 to 4 Coresta units, and more preferably about 3 Coresta units.

[0032] The permeability of the wrapper may be determined using the international standard test method ISO 2965:2009, and the results may be presented as cubic centimeters per minute per square centimeter, and may be referred to as "Cholesta units."

[0033] The wrapper may or may not be embossed. The wrapper may be both perforated and embossed.

[0034] The term "embossment" is used herein to refer to protrusions formed on the surface of a wrapper. These protrusions may be engraved, molded, or stamped into the wrapper. A portion of a wrapper with such embossment is said to be embossed.

[0035] The wrapper may include an embossed portion. The embossed portion of the wrapper may have a single embossment. The embossed portion of the wrapper may have multiple embossments. The one or more embossments may have a depth of 0.07 mm to 0.21 mm, preferably 0.10 mm to 0.18 mm, and more preferably 0.12 mm to 0.16 mm. Each embossment may also have a pitch of 0.2 mm to 0.4 mm, preferably 0.25 mm to 0.35 mm, and more preferably 0.275 mm to 0.325 mm.

[0036] The wrapper may have a roughness of about 50 Bekk seconds to about 1000 Bekk seconds, preferably about 100 Bekk seconds to about 200 Bekk seconds. Roughness, expressed in Bekk seconds, can be measured by a standard test using a BEKK Smoothness Tester, which generates a vacuum and measures the time it takes for the vacuum to drop from 50.66 kPa to 48.00 kPa. This test is recognized by international standard ISO 5627.

[0037] The thickness of the wrapper may be determined in accordance with ISO 534:2011. The thickness of the wrapper may be determined in accordance with ASTM E252-06(2021)e1. Generally, for an embossed wrapper, the local thickness at the embossed location may be less than the thickness at a non-embossed location. As used herein, for an embossed wrapper, the thickness of the wrapper refers to the thickness at a non-embossed location. For an embossed wrapper, the thickness of the wrapper may be determined before the wrapper is embossed.

[0038] Unless otherwise defined, all measurements described herein are performed after sample conditioning according to ISO standard 3402:1999.

[0039] The wrapper may be in direct physical contact with the aerosol-forming substrate, in which case there is no layer of material between the wrapper and the aerosol-forming substrate.

[0040] The wrapper may comprise one or more of cardboard, plastic, and metal foil.

[0041] The wrapper may comprise one or more cellulosic materials, such as paper, wood, textiles, natural fibers, and man-made fibers. The wrapper may comprise a paper layer. The wrapper may be made from one or more cellulosic materials, such as paper, wood, textiles, natural fibers, and man-made fibers. The wrapper may be a paper wrapper. The wrapper may be made of paper. The wrapper may be made of a paper layer. The wrapper may be made of a single paper sheet.

[0042] The wrapper may comprise a laminate sheet. The wrapper may be made of a single laminate sheet. The laminate sheet may be a laminate of a paper layer and an aluminum layer.

[0043] The wrapper may be formed from a laminate material including multiple layers. The wrapper may be formed from a metal co-laminate sheet, for example, an aluminum co-laminate sheet. The metal layer of the co-laminate sheet may have a basis weight of 12 grams per square meter to 25 grams per square meter, preferably 15 grams per square meter to 20 grams per square meter. The metal layer of the co-laminate sheet may have a thickness of 2 micrometers to 15 micrometers, preferably 3 micrometers to 12 micrometers, and more preferably 5 micrometers to 10 micrometers.

[0044] The wrapper may be a paper wrapper containing PVOH (polyvinyl alcohol) or silicon (or polysiloxane). The addition of PVOH (polyvinyl alcohol) or silicon (or polysiloxane) may improve the grease barrier properties of the wrapper.

[0045] The wrapper may include a flame retardant composition comprising one or more flame retardant compounds. The term "flame retardant compound" is used herein to describe compounds that, when added to or otherwise incorporated into a carrier substrate, such as a paper or plastic compound, provide varying degrees of flammability protection to the carrier substrate.

[0046] Many suitable flame retardant compounds are known to those skilled in the art. In particular, several flame retardant compounds and formulations suitable for treating cellulosic materials are known and disclosed and may find use in the manufacture of wrappers for aerosol-generating articles according to the present invention.

[0047] In a particularly preferred embodiment, in addition to the wrapper at least partially surrounding the aerosol-forming substrate and containing less than 45 weight percent calcium carbonate as described herein, one or more of the components of the aerosol-generating article may each be individually surrounded by its own single-component wrapper.

[0048] Preferably, at least one of the components of the aerosol-generating article is enclosed in a hydrophobic wrapper.

[0049] The term "hydrophobicity" refers to a surface that exhibits water-repellent properties. One useful way to determine this is to measure the water contact angle. The "water contact angle" is the angle traditionally measured through a liquid where the liquid / vapor interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via Young's equation. Hydrophobicity or water contact angle may be determined by utilizing the TAPPI T558 test method, and the results are expressed as interfacial contact angles, reported in degrees, which can range from approximately zero to approximately 180 degrees.

[0050] In preferred embodiments, the hydrophobic wrapper comprises a paper layer having a water contact angle of about 30 degrees or greater, preferably about 35 degrees or greater, or about 40 degrees or greater, or about 45 degrees or greater.

[0051] By way of example, the paper layer may comprise PVOH (polyvinyl alcohol) or silicon. The PVOH may be applied to the paper layer as a surface coating, or the paper layer may comprise a surface treatment that includes PVOH or silicon.

[0052] The wrapper at least partially enclosing the aerosol-forming substrate and containing less than 45 weight percent calcium carbonate may comprise alkaline paper having a pH value greater than 7. The wrapper may have a pH value greater than 8. The wrapper may have a pH value less than 7.8. The wrapper may have a pH value greater than 7 but less than 7.8.

[0053] The aerosol-forming substrate may have a pH value of 3.5 to 4.9, preferably 3.6 to 4.9, more preferably 3.7 to 4.9, more preferably 3.8 to 4.9.

[0054] The pH value of the wrapper may be measured by ISO protocol ISO 6588-1. The pH value of the wrapper is preferably measured by test method A, as described herein. The pH value of the aerosol-forming substrate may be measured by test method B, as described herein.

[0055] Test Method A - Determine the pH value of the wrapper: Step 1: The sample is cut or torn with a knife or cutter into pieces approximately 1 square centimeter in size.

[0056] Step 2: Weigh 2.5 grams ± 0.1 grams of sample conditioned for 40 hours in air at 22.5 degrees Celsius ± 2.5 degrees Celsius and 50 percent ± 5 percent relative humidity into a 250 milliliter flask.

[0057] Step 3: Add 22.5 grams of deionized water.

[0058] Step 4: Ensure all pieces are immersed. Seal the flask with a ground glass stopper and leave at a temperature of 22.5°C + / - 2.5°C for 10 hours. Shake the flask at least once during this time.

[0059] Step 5: The extract is filtered through a coarse glass filter into a small beaker.

[0060] Step 6: Measure the pH value using a pH meter with a glass electrode and a calomel electrode, or a pH meter with a combination electrode that reads to at least 0.05 pH units. Operate the pH meter according to the manufacturer's instructions. After calibrating the pH meter, rinse the electrode several times with deionized water and once with a small amount of the extract. Ensure the temperature of the extract is 22.5°C + / - 2.5°C. Immerse the electrode in the extract. Record the pH value when there is no measurable drift within 30 seconds.

[0061] Before measuring the next sample, carefully rinse the electrode with deionized water to remove any traces of sample or buffer. At the end of the series of measurements, check the electrode with the same buffer. The results for both solutions should agree with the correct value to within 0.1 pH units. If not, repeat the procedure.

[0062] Step 7: Measure the pH value twice according to step 6 and calculate the average of the duplicate measurements. Individual results should not differ by more than 0.2 pH units. If not, repeat the measurement with two additional extracts and report the average and range of all measurements.

[0063] Test Method B - Measuring the pH value of the aerosol-forming substrate: Step 1: If the aerosol-forming substrate is provided in the form of a sheet-like structure, cut the sample with a knife or cutter or tear it into pieces approximately 1 square centimeter in size. If the aerosol-forming substrate is provided as loose material, proceed with the loose sample as is.

[0064] Proceed to steps 2 and 3 as defined in Test Method A.

[0065] Step 4: The material is ground in a disperser (e.g., an "IKA T 18" device). The flask is sealed with a ground glass stopper and left to stand at a temperature of 22.5°C + / - 2.5°C for 10 hours. Shake the flask at least once during this time.

[0066] Perform steps 5 through 7 defined in Test Method A.

[0067] As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may be in solid or liquid form. The aerosol-forming substrate may be solid or liquid, or may contain both solid and liquid components. The aerosol-forming substrate may be part of an aerosol-generating article. The terms "aerosol" and "vapor" are used interchangeably.

[0068] The aerosol-forming substrate may comprise one or more of tobacco, nicotine, an aerosol-forming film, a gel composition, and a flavoring agent.

[0069] The aerosol-forming substrate may comprise a total aerosol-former content of at least 10 weight percent, preferably at least 15 weight percent, more preferably at least 20 weight percent, more preferably at least 25 weight percent, more preferably at least 30 weight percent, more preferably at least 35 weight percent, more preferably at least 40 weight percent, more preferably at least 45 weight percent, more preferably at least 50 weight percent, more preferably at least 55 weight percent on a dry weight basis.

[0070] The aerosol-forming substrate may comprise at least 35 percent by weight of one or more aerosol formers. The aerosol-forming substrate may comprise at least 35 percent by weight of one or more aerosol formers, based on the dry weight of the aerosol-forming substrate. Unless otherwise specified, all weight percentages stated herein are on a dry weight basis. The content of aerosol formers may be based on the total dry weight of the aerosol-forming substrate.

[0071] The aerosol former can be any suitable known compound or mixture of compounds that promotes the formation of a dense, stable aerosol during use. The aerosol former can promote the aerosol to be substantially resistant to thermal decomposition at temperatures typically encountered during use of the aerosol-generating article. Suitable aerosol formers include, for example, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, propylene glycol, glycerin, etc.), esters of polyhydric alcohols (e.g., glycerol mono-, di-, or triacetate, etc.), aliphatic esters of mono-, di-, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.), and combinations thereof. Preferably, the one or more aerosol formers comprise one or both of glycerol and propylene glycol. The one or more aerosol formers may consist of one or both of glycerol and propylene glycol. Preferably, the aerosol-forming substrate comprises glycerol. The terms "glycerin" and "glycerol" are used interchangeably herein.

[0072] The aerosol-forming substrate may comprise 80 percent or less by weight of the aerosol former, based on the dry weight of the aerosol-forming substrate. The aerosol-forming substrate may comprise 60 percent or less by weight of the aerosol former, based on the dry weight of the aerosol-forming substrate. The aerosol-forming substrate may comprise 40 percent or less by weight of the aerosol former, based on the dry weight of the aerosol-forming substrate.

[0073] The aerosol-forming substrate may comprise from 35 weight percent to 80 weight percent, or from 35 weight percent to 60 weight percent, or from 35 weight percent to 55 weight percent, or from 35 weight percent to 50 weight percent, or from 35 weight percent to 40 weight percent of the aerosol former, based on the dry weight of the aerosol-forming substrate.

[0074] The total aerosol-forming substance content of the aerosol-forming substrate may be at least 40 weight percent, preferably at least 45 weight percent, more preferably at least 50 weight percent, more preferably at least 55 weight percent. The total aerosol-forming substance content of the aerosol-forming substrate may be 35 weight percent to 75 weight percent, preferably 40 weight percent to 60 weight percent, more preferably 45 weight percent to 55 weight percent.

[0075] The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise one or more carboxylic acids. The aerosol-forming substrate may comprise nicotine, one or more cellulosic agents, one or more aerosol formers, and one or more carboxylic acids.

[0076] The one or more carboxylic acids may be selected from fumaric acid, maleic acid, and malic acid. The one or more carboxylic acids may be selected from fumaric acid and maleic acid. The one or more carboxylic acids may be fumaric acid. The one or more carboxylic acids may have a pKa in water of 3.5 or less at 25°C. The aerosol-forming substrate may comprise one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid, and levulinic acid.

[0077] The aerosol-forming substrate may comprise, on a dry weight basis, from 0.1 to 8 weight percent of one or more carboxylic acids, preferably from 0.5 to 6 weight percent, more preferably from 0.5 to 5 weight percent, more preferably from 0.5 to 4 weight percent, more preferably from 1.5 to 4 weight percent, more preferably from 2 to 4 weight percent. The carboxylic acid content may be based on the total dry weight of the aerosol-forming substrate.

[0078] The aerosol-forming substrate may comprise one or more carboxylic acids that contain no non-carboxylic hydroxyl groups.

[0079] In one preferred embodiment of the invention, the aerosol-forming substrate comprises fumaric acid and the wrapper may be free of filler material.

[0080] The aerosol-forming substrate may comprise nicotine and one or more carboxylic acids, and the molar ratio of total carboxylic acids to nicotine may be from 0.5:1 to 5:1, preferably from 1:1 to 4:1, more preferably from 2:1 to 3.5:1, more preferably from 0 to 0.3, more preferably from 0 to 0.2, more preferably from 0 to 0.1.

[0081] The aerosol-forming substrate may comprise, on a dry weight basis, from 0.5 to 5 weight percent, preferably from 0.5 to 3 weight percent, more preferably from 1 to 2 weight percent fumaric acid.

[0082] The aerosol-forming substrate may comprise, on a dry weight basis, from 0.5 to 5 weight percent, preferably from 0.5 to 3 weight percent, more preferably from 1 to 2 weight percent maleic acid.

[0083] The aerosol-forming substrate may contain one or both of fumaric acid and maleic acid, and the total amount of fumaric acid and maleic acid contained in the aerosol-forming substrate may be 0.5 to 5 weight percent, preferably 0.5 to 3 weight percent, and more preferably 1 to 2 weight percent, on a dry weight basis.

[0084] The aerosol-forming substrate may comprise less than 6 weight percent, preferably less than 4 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent malic acid on a dry weight basis.

[0085] The aerosol-forming substrate may have a total cellulosic agent content of about 35 to 50 percent by weight. The aerosol-forming substrate may include one or more cellulosic film-forming agents selected from carboxymethyl cellulose and hydroxypropyl methyl cellulose. The aerosol-forming substrate may include one or more cellulosic reinforcing agents selected from cellulose fibers, microcrystalline cellulose, and cellulose powder. The total cellulosic agent content may be based on the total dry weight of the aerosol-forming substrate.

[0086] The aerosol-forming substrate can be an aerosol-forming film. The aerosol-forming substrate can be a solid aerosol-forming film. The solid aerosol-forming film can be solid at room temperature. The solid aerosol-forming film can remain solid when heated to a temperature of between 180 degrees Celsius and 350 degrees Celsius.

[0087] The aerosol-forming substrate may be provided in the form of a gel.

[0088] The aerosol-forming substrate may comprise a tobacco content of less than 75 weight percent, preferably less than 70 weight percent, more preferably less than 65 weight percent, more preferably less than 60 weight percent, more preferably less than 55 weight percent, more preferably less than 50 weight percent, more preferably less than 45 weight percent, more preferably less than 40 weight percent, more preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent on a dry weight basis. The tobacco content may be based on the total dry weight of the aerosol-forming substrate.

[0089] The aerosol-forming substrate may be substantially tobacco-free.The aerosol-forming substrate may be tobacco-free.

[0090] The aerosol-forming substrate may comprise one or more carboxylic acids, and the aerosol-forming substrate may have a total carboxylic acid content of 0.5 weight percent or greater. The aerosol-forming substrate may be free of iota-carrageenan or kappa-carrageenan.

[0091] The aerosol-forming substrate may be a solid aerosol-forming substrate. As used herein with respect to the present invention, the term "solid" is used to describe an aerosol-forming substrate that has a stable size and shape and does not flow at room temperature, which is about 23 degrees Celsius.

[0092] For example, the aerosol-forming substrate may remain solid when heated to a temperature of from 180°C to 350°C, from 200°C to 320°C, from 220°C to 300°C, or from 240°C to 280°C.

[0093] The aerosol-forming substrate may be an aerosol-forming film.

[0094] The term "film" as used herein is used to describe a solid layered element having a thickness smaller than its width or length. The film can be self-supporting. In other words, even if the film is obtained by casting a film-forming formulation on a support surface, it can have cohesive and mechanical properties that allow it to be separated from the support surface. Alternatively, the film can be placed on a support or sandwiched between other materials. This can enhance the mechanical stability of the film.

[0095] The solid aerosol-forming substrate may be a solid aerosol-forming film.

[0096] The aerosol-forming film may include one or more aerosol formers described herein; preferably, the aerosol former includes or is glycerin. The aerosol-forming film may have an aerosol-former content of at least 35 percent by weight on a dry weight basis. Preferably, the aerosol-forming film has an aerosol-former content of at least 40 percent by weight on a dry weight basis. More preferably, the aerosol-forming film has an aerosol-former content of at least 45 percent by weight on a dry weight basis. More preferably, the aerosol-forming film has an aerosol-former content of at least 50 percent by weight on a dry weight basis.

[0097] Preferably, the aerosol-forming film has an aerosol-former content of 80 weight percent or less on a dry weight basis. More preferably, the aerosol-forming film has an aerosol-former content of 75 weight percent or less on a dry weight basis. More preferably, the aerosol-forming film has an aerosol-former content of 70 weight percent or less on a dry weight basis.

[0098] The aerosol-forming substrate may be in the form of an aerosol-forming film comprising a cellulosic film-forming agent, nicotine, and an aerosol former. The aerosol-forming film may further comprise a cellulosic reinforcement agent. The aerosol-forming film may further comprise water, preferably up to about 30 weight percent water.

[0099] As used herein with respect to the present invention, the term "thickness" is used to describe the smallest dimension between opposing substantially parallel surfaces of a solid aerosol-forming film.

[0100] The solid aerosol-forming film may have a thickness of 0.05 millimeters or more, 0.1 millimeters or more, 0.2 millimeters or more, or 0.3 millimeters or more. The solid aerosol-forming film may have a thickness of 1.2 millimeters or less, 1 millimeter or less, 0.8 millimeters or less, 0.6 millimeters or less, or 0.4 millimeters or less.

[0101] The solid aerosol-forming film can have a basis weight of 85 grams per square meter or more, 100 grams per square meter or more, 120 grams per square meter or more, or 140 grams per square meter or more. The solid aerosol-forming film can have a basis weight of 300 grams per square meter or less, 280 grams per square meter or less, or 260 grams per square meter or less.

[0102] The solid aerosol-forming film can be formed by any suitable method, for example, the solid aerosol-forming film can be formed by batch casting, continuous casting, or extrusion.

[0103] The solid aerosol-forming film may be self-supporting, that is, the properties of the solid aerosol-forming film may be such that the solid aerosol-forming film can be separated from a support surface, even if the solid aerosol-forming film is formed by casting a slurry onto the support surface.

[0104] The solid aerosol-forming film may be deposited on a support, or may be sandwiched between other materials, which may enhance the mechanical stability of the solid aerosol-forming film. For example, the solid aerosol-forming film may be deposited on a layered support.

[0105] The solid aerosol-forming film may be cut or otherwise divided into a plurality of strips or pieces that may be wrapped to form the aerosol-forming portion that is enclosed by the wrapper.

[0106] The solid aerosol-forming film may be assembled before being inserted into the aerosol-forming portion. The solid aerosol-forming film may be textured, which facilitates assembly of the solid aerosol-forming film before being inserted into the aerosol-forming portion.

[0107] As used herein in connection with the present invention, the term "textured" is used to describe a solid aerosol-forming film that is crimped, embossed, debossed, perforated, or otherwise modified. A textured solid aerosol-forming film may include a plurality of spaced apart indentations, protrusions, perforations, or a combination thereof.

[0108] The solid aerosol-forming film may be crimped.

[0109] The term "crimped" as used herein in connection with the present invention is intended to be synonymous with the term "crinkled" and is used to describe a solid aerosol-forming film having a plurality of substantially parallel ridges or corrugations.

[0110] The solid aerosol-forming film may be incorporated directly into the aerosol-forming portion.

[0111] The solid aerosol-forming film can be applied to a layered support before being incorporated into the aerosol-forming portion. For example, the solid aerosol-forming film can be applied to the surface of a sheet material. Sheet materials suitable for use as a layered support include, but are not limited to, paper, cardboard, and homogenized plant material. For example, the solid aerosol-forming film can be applied to a paper sheet, an aluminum-coated paper sheet, or a polyethylene-coated paper sheet.

[0112] The layered substrate to which the solid aerosol-forming film is applied can be cut or otherwise divided into a plurality of strips or pieces, as described above.

[0113] The layered substrate to which the solid aerosol-forming film is applied can be assembled as described above.

[0114] The layered substrate to which the solid aerosol-forming film is applied may be textured as described above.

[0115] As used herein with respect to the present invention, the term "aerosol former" is used to describe a compound that, in use, facilitates the formation of an aerosol and that is preferably substantially resistant to thermal decomposition at the operating temperatures of the aerosol-generating article or aerosol-generating system comprising the solid aerosol-forming substrate.

[0116] Examples of suitable aerosol formers include polyhydric alcohols (such as 1,3-butanediol, glycerin, 1,3-propanediol, propylene glycol, and triethylene glycol), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate).

[0117] The aerosol-forming substrate may have a total aerosol-former content of 35 weight percent or more. The aerosol-forming substrate may have a total aerosol-former content of 40 weight percent or more, or 45 weight percent or more, or 50 weight percent or more.

[0118] As used herein with respect to the present invention, the term "total aerosol former content" is used to describe the combined content of all aerosol formers in an aerosol-forming substrate.

[0119] The solid aerosol-forming substrate may have a total aerosol-former content of 46 weight percent or more, 48 weight percent or more, 50 weight percent or more, or 52 weight percent or more.

[0120] The solid aerosol-forming substrate may have a total aerosol-former content of 62 weight percent or less, 60 weight percent or less, 58 weight percent or less, 56 weight percent or less, or 54 weight percent or less.

[0121] The solid aerosol-forming substrate may have a total aerosol-former content of 42 weight percent to 62 weight percent, 46 weight percent to 60 weight percent, 46 weight percent to 58 weight percent, 46 weight percent to 56 weight percent, or 46 weight percent to 54 weight percent.

[0122] Preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols.

[0123] The solid aerosol-forming substrate may have a total polyhydric alcohol content of 45 weight percent or greater, 46 weight percent or greater, 48 weight percent or greater, 50 weight percent or greater, or 52 weight percent or greater.

[0124] Preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols selected from 1,3-butanediol, glycerin, 1,3-propanediol, propylene glycol, and triethylene glycol.

[0125] More preferably, the solid aerosol-forming substrate comprises one or more polyhydric alcohols selected from glycerin and propylene glycol. Most preferably, the solid aerosol-forming substrate comprises glycerin.

[0126] The solid aerosol-forming substrate may comprise one or more carboxylic acids having a pKa in water at 25°C of 3.5 or less.

[0127] As used herein in connection with the present invention, the term "carboxylic acid having a pKa in water of 3.5 or less at 25°C" is used to describe monobasic carboxylic acids having a pKa in water of 3.5 or less at 25°C, and polybasic carboxylic acids having a pKa in water of 3.5 or less at 25°C.

[0128] As used herein in connection with the present invention, the term "total carboxylic acid content" is used to describe the combined content of all carboxylic acids in a solid aerosol-generating substrate. For example, if a solid aerosol-generating substrate contains carboxylic acids consisting of benzoic acid and fumaric acid, the term "total carboxylic acid content" describes the combined benzoic acid and fumaric acid content of the solid aerosol-generating substrate.

[0129] The solid aerosol-generating substrate may have a total carboxylic acid content of 1 weight percent or greater, 1.5 weight percent or greater, or 2 weight percent or greater.

[0130] The solid aerosol-generating substrate may have a total carboxylic acid content of 8 weight percent or less, 6 weight percent or less, or 4 weight percent or less.

[0131] The solid aerosol-generating substrate may have a total carboxylic acid content of from 0.5 weight percent to 8 weight percent, from 0.5 weight percent to 6 weight percent, or from 0.5 weight percent to 4 weight percent.

[0132] The solid aerosol-generating substrate may have a total carboxylic acid content of from 1 weight percent to 8 weight percent, from 1 weight percent to 6 weight percent, or from 1 weight percent to 4 weight percent.

[0133] The solid aerosol-generating substrate may have a total carboxylic acid content of from 1.5 weight percent to 8 weight percent, from 1.5 weight percent to 6 weight percent, or from 1.5 weight percent to 4 weight percent.

[0134] The solid aerosol-generating substrate may have a total carboxylic acid content of from 2 weight percent to 8 weight percent, from 2 weight percent to 6 weight percent, or from 2 weight percent to 4 weight percent.

[0135] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be 0.5:1 or greater, 1:1 or greater, 1.5:1 or greater, or 2:1 or greater.

[0136] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be 5:1 or less, 4.5:1 or less, 4:1 or less, or 3.5:1 or less.

[0137] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 0.5:1 to 5:1, from 0.5:1 to 4.5:1, from 0.5:1 to 4:1, or from 0.5:1 to 3.5:1.

[0138] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 1:1 to 5:1, from 1:1 to 4.5:1, from 1:1 to 4:1, or from 1:1 to 3.5:1.

[0139] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 1.5:1 to 5:1, from 1.5:1 to 4.5:1, from 1.5:1 to 4:1, or from 1.5:1 to 3.5:1.

[0140] The molar ratio of total carboxylic acids to nicotine in the solid aerosol-generating substrate may be from 2:1 to 5:1, from 2:1 to 4.5:1, from 2:1 to 4:1, or from 2:1 to 3.5:1.

[0141] The solid aerosol-generating substrate may have a fumaric acid content of 0.5 weight percent or more, 1 weight percent or more, 1.5 weight percent or more, or 2 weight percent or more.

[0142] The solid aerosol-generating substrate may have a fumaric acid content of 8 weight percent or less, 6 weight percent or less, or 4 weight percent or less.

[0143] The solid aerosol-generating substrate may have a fumaric acid content of from 0.5 weight percent to 8 weight percent, from 0.5 weight percent to 6 weight percent, or from 0.5 weight percent to 4 weight percent.

[0144] The solid aerosol-generating substrate may have a fumaric acid content of from 1 weight percent to 8 weight percent, from 1 weight percent to 6 weight percent, or from 1 weight percent to 4 weight percent.

[0145] The solid aerosol-generating substrate may have a fumaric acid content of 1.5 weight percent to 8 weight percent, 1.5 weight percent to 6 weight percent, or 1.5 weight percent to 4 weight percent.

[0146] The solid aerosol-generating substrate may have a fumaric acid content of from 2 weight percent to 8 weight percent, from 2 weight percent to 6 weight percent, or from 2 weight percent to 4 weight percent.

[0147] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 0.5:1 or greater, 1:1 or greater, 1.5:1 or greater, or 2:1 or greater.

[0148] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 4:1 or less, or 3.5:1 or less, 3:1 or less, or 2.5:1 or less.

[0149] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 0.5:1 to 4:1, 0.5:1 to 3.5:1, 0.5:1 to 3:1, or 0.5:1 to 2.5:1.

[0150] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 1:1 to 4:1, 1:1 to 3.5:1, 1:1 to 3:1, or 1:1 to 2.5:1.

[0151] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be from 1.5:1 to 4:1, from 1.5:1 to 3.5:1, from 1.5:1 to 3:1, or from 1.5:1 to 2.5:1.

[0152] The molar ratio of fumaric acid to nicotine in the solid aerosol-generating substrate may be 2:1 to 4:1, 2:1 to 3.5:1, 2:1 to 3:1, or 2:1 to 2.5:1.

[0153] The solid aerosol-forming substrate may comprise one or more cellulosic agents.

[0154] As used herein in connection with the present invention, the term "cellulosic agent" is used to describe a cellulose-based material. The term "cellulosic film former" may be used to describe a cellulose polymer that has the ability to form a continuous film by itself or in the presence of an auxiliary thickener.

[0155] Examples of cellulosic agents include cellulosic film formers, cellulosic reinforcing agents, and cellulosic binders.

[0156] The term "total cellulosic agent" as used herein in connection with the present invention is used to describe the total content of all cellulosic agents in a solid aerosol-forming substrate. For example, if a solid aerosol-forming substrate contains multiple cellulosic agents consisting of a cellulosic film-forming agent, a cellulosic reinforcing agent, and a cellulosic binder, the term "total cellulosic agent content" describes the combined cellulosic film-forming agent content, cellulosic reinforcing agent content, and cellulosic binder content of the solid aerosol-forming substrate.

[0157] The solid aerosol-forming substrate may have a total cellulosic agent content of 25 weight percent or more, or 30 weight percent or more. Preferably, the solid aerosol-forming substrate has a total cellulosic agent content of 35 weight percent or more. The solid aerosol-forming substrate may have a total cellulosic agent content of 36 weight percent or more, 38 weight percent or more, or 40 weight percent or more.

[0158] The solid aerosol-forming substrate may have a total cellulosic agent content of 52 weight percent or less, 50 weight percent or less, 48 ​​weight percent or less, 46 weight percent or less, or 44 weight percent or less.

[0159] The solid aerosol-forming substrate may have a total cellulosic agent content of 35 weight percent to 52 weight percent, 35 weight percent to 50 weight percent, 35 weight percent to 48 weight percent, 35 weight percent to 46 weight percent, or 35 weight percent to 44 weight percent.

[0160] The solid aerosol-forming substrate may comprise one or more cellulosic film-forming agents.

[0161] As used herein in connection with the present invention, the term "cellulosic film former" is used to describe a cellulose polymer that has the ability to form a continuous film by itself or in the presence of an auxiliary thickener.

[0162] Advantageously, the solid aerosol-forming substrate may comprise one or more cellulosic film-forming agents selected from carboxymethyl cellulose (CMC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose (HEMC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), and methyl cellulose (MC). Preferably, the solid aerosol-forming substrate comprises carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC).

[0163] Preferably, the cellulosic film former is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methylcellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof.

[0164] More preferably, the cellulosic film-forming agent is selected from the group consisting of hydroxypropylmethylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), and combinations thereof.

[0165] In a particularly preferred embodiment, the cellulosic film-forming agent is HPMC.

[0166] One or more cellulosic film-forming agents may act as binders for the solid aerosol-forming substrate.

[0167] The solid aerosol-forming substrate may have a total cellulosic film-forming agent content of 15 weight percent or more, 20 weight percent or more, or 25 weight percent or more.

[0168] The solid aerosol-forming substrate may have a total cellulosic film-forming agent content of 40 weight percent or less, 35 weight percent or less, or 30 weight percent or less.

[0169] The solid aerosol-forming substrate may have a total cellulosic film-forming agent content of 10 to 40 percent, 15 to 35 percent, or 15 to 30 percent by weight. The aerosol-forming film may have a cellulosic film-forming agent content of 10 to 40 percent, or 15 to 35 percent, or 20 to 30 percent by weight on a dry weight basis.

[0170] The solid aerosol-forming substrate may include one or more cellulosic reinforcing agents.

[0171] Inclusion of one or more cellulosic reinforcing agents in the solid aerosol-forming substrate can advantageously increase the tensile strength of the solid aerosol-forming substrate. In particular, when the solid aerosol-forming substrate is a solid aerosol-forming film, inclusion of one or more cellulosic reinforcing agents in the solid aerosol-forming substrate can advantageously increase the tensile strength of the solid aerosol-forming film. Solid aerosol-forming substrates with high tensile strength can advantageously be less likely to deteriorate or break during manufacture and storage.

[0172] Advantageously, the solid aerosol-forming substrate may comprise one or more cellulosic reinforcing agents selected from cellulose fibers, cellulose powder, and microcrystalline cellulose (MCC). Preferably, the cellulosic reinforcing agent is selected from the group consisting of cellulose fibers, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

[0173] Preferably, the solid aerosol-forming substrate comprises cellulose fibers, which can be particularly effective in increasing the tensile strength of the solid aerosol-forming substrate.

[0174] The aerosol-forming film may have a cellulosic reinforcing agent content of from 0.5 weight percent to 40 weight percent on a dry weight basis, or from 5 weight percent to 30 weight percent on a dry weight basis, or from 10 weight percent to 25 weight percent on a dry weight basis.

[0175] The solid aerosol-forming substrate may have a total cellulosic reinforcement content of 5 weight percent or more, 10 weight percent or more, or 15 weight percent or more.

[0176] As used herein in connection with the present invention, the term "total cellulosic reinforcing agent content" is used to describe the combined content of all cellulosic reinforcing agents in the solid aerosol-forming substrate.

[0177] The solid aerosol-forming substrate may have a total cellulosic reinforcing agent content of 30 weight percent or less, 25 weight percent or less, or 20 weight percent or less.

[0178] The solid aerosol-forming substrate may have a total cellulosic reinforcement agent content of from 5 weight percent to 30 weight percent, from 5 weight percent to 25 weight percent, or from 5 weight percent to 20 weight percent.

[0179] The aerosol-forming film may further comprise carboxymethylcellulose, preferably sodium carboxymethylcellulose.

[0180] The aerosol-forming film may have a carboxymethylcellulose content of from 1 weight percent to 15 weight percent, or from 2 weight percent to 12 weight percent, or from 4 weight percent to 10 weight percent, on a dry weight basis.

[0181] The solid aerosol-forming substrate may comprise water.

[0182] The solid aerosol-forming substrate may have a water content of 5 weight percent or more, 10 weight percent or more, 15 weight percent or more, or 17 weight percent or more, based on the total weight of the solid aerosol-forming substrate.

[0183] The solid aerosol-forming substrate may have a water content of 35 weight percent or less, 30 weight percent or less, or 25 weight percent or less, based on the total weight of the solid aerosol-forming substrate.

[0184] The solid aerosol-forming substrate may have a water content of 5 weight percent to 35 weight percent, 5 weight percent to 30 weight percent, or 5 weight percent to 25 weight percent, based on the total weight of the solid aerosol-forming substrate.

[0185] The solid aerosol-forming substrate may include one or more non-cellulosic thickeners.

[0186] As used herein in connection with the present invention, the term "non-cellulosic thickener" is used to describe a non-cellulosic substance that, when added to an aqueous or non-aqueous liquid composition, increases the viscosity of the liquid composition without substantially altering other properties of the liquid composition. One or more non-cellulosic thickeners may increase the stability and improve the suspension of ingredients in the liquid composition. A thickener may also be referred to as a "thickener" or "rheology modifier" or "viscosifying agent."

[0187] The solid aerosol-forming substrate may comprise one or more non-cellulosic thickeners selected from alginate, gellan gum, guar gum, gum arabic, locust bean gum, pectin, starch, and xanthan gum.

[0188] The solid aerosol-forming substrate may have a total cellulosic thickener content of 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more.

[0189] The solid aerosol-forming substrate may have a total non-cellulosic thickener content of 10 weight percent or less, 8 weight percent or less, or 6 weight percent or less.

[0190] The solid aerosol-forming substrate may have a total non-cellulosic thickener content of from 1 weight percent to 10 weight percent, from 1 weight percent to 8 weight percent, or from 1 weight percent to 6 weight percent.

[0191] The solid aerosol-forming substrate may include one or more flavoring agents.

[0192] Suitable flavoring agents are known in the art and include, but are not limited to, menthol.

[0193] As used herein in connection with the present invention, the term "menthol" is used to describe the compound 2-isopropyl-5-methylcyclohexanol in any of its isomeric forms.

[0194] The solid aerosol-forming substrate may have a total flavorant content of 0.5 weight percent or more, 1 weight percent or more, 2 weight percent or more, or 3 weight percent or more.

[0195] The solid aerosol-forming substrate may have a total flavorant content of 6 weight percent or less, 5 weight percent or less, or 4 weight percent or less.

[0196] The solid aerosol-forming substrate may have a total flavorant content of from 0.5 weight percent to 6 weight percent, from 0.5 weight percent to 5 weight percent, or from 0.5 weight percent to 4 weight percent.

[0197] The solid aerosol-forming substrate may have a total flavorant content of from 1 weight percent to 6 weight percent, from 1 weight percent to 5 weight percent, or from 1 weight percent to 4 weight percent.

[0198] The solid aerosol-forming substrate may be a substantially tobacco-free solid aerosol-forming substrate.

[0199] As used herein in connection with the present invention, the term "substantially tobacco-free solid aerosol-forming substrate" is used to describe a solid aerosol-forming substrate having a tobacco content of less than 1 weight percent. For example, the solid aerosol-forming substrate may have a tobacco content of less than 0.75 weight percent, less than 0.5 weight percent, or less than 0.25 weight percent.

[0200] The solid aerosol-forming substrate may be a tobacco-free aerosol-forming film.

[0201] As used herein in connection with the present invention, the term "tobacco-free solid aerosol-forming substrate" is used to describe a solid aerosol-forming substrate having zero percent tobacco content by weight.

[0202] Preferably, the aerosol-forming film comprises nicotine.

[0203] As used herein with respect to the present invention, the term "nicotine" is used to describe nicotine, nicotine base, or nicotine salts. In embodiments where the aerosol-forming film comprises nicotine base or nicotine salts, the amounts of nicotine recited herein are the amounts of free base nicotine or the amounts of protonated nicotine, respectively.

[0204] The aerosol-forming film may contain natural or synthetic nicotine.

[0205] The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix.

[0206] The aerosol-forming film may include one or more monobasic nicotine salts.

[0207] As used herein in connection with the present invention, the term "monobasic nicotine salt" is used to describe a nicotine salt of a monobasic acid.

[0208] Preferably, the aerosol-forming film comprises at least 0.5 weight percent nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises at least 1 weight percent nicotine on a dry weight basis. Even more preferably, the aerosol-forming film comprises at least 2 weight percent nicotine on a dry weight basis. Additionally, or alternatively, the aerosol-forming film preferably comprises less than 10 weight percent nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises less than 8 weight percent nicotine on a dry weight basis. More preferably, the aerosol-forming film comprises less than 6 weight percent nicotine on a dry weight basis.

[0209] For example, the aerosol-forming film may include, on a dry weight basis, from 0.5 weight percent to 10 weight percent nicotine, or from 1 weight percent to 8 weight percent nicotine, or from 2 weight percent to 6 weight percent nicotine.

[0210] The aerosol-forming film may be a substantially tobacco-free aerosol-forming film.

[0211] In preferred embodiments, the aerosol-forming film comprises an acid. More preferably, the aerosol-forming film comprises one or more organic acids. Even more preferably, the aerosol-forming film comprises one or more carboxylic acids. In particularly preferred embodiments, the acid is lactic acid, benzoic acid, fumaric acid, or levulinic acid.

[0212] Preferably, the aerosol-forming film comprises, on a dry weight basis, from 0.25 weight percent to 3.5 weight percent acid, or from 0.5 weight percent to 3 weight percent acid, or from 1 weight percent to 2.5 weight percent acid.

[0213] The aerosol-forming film may have a thickness of about 0.1 millimeter to about 1 millimeter, more preferably about 0.1 millimeter to about 0.75 millimeter, more preferably about 0.1 millimeter to about 0.5 millimeter. In particularly preferred embodiments, a layer of the film-forming composition is formed having a thickness of about 50 micrometers to 400 micrometers, more preferably about 100 micrometers to 200 micrometers.

[0214] The aerosol-forming film may optionally be provided on a suitable carrier element.

[0215] The aerosol-forming substrate may comprise a gel composition. The aerosol-forming substrate may comprise a gel composition comprising nicotine, at least one gelling agent, and an aerosol former. Preferably, the gel composition is substantially tobacco-free.

[0216] The preferred weight ranges of nicotine in the gel composition are the same as those defined above in connection with the aerosol-forming film.

[0217] The gel composition preferably comprises at least 50 weight percent aerosol former, more preferably at least 60 weight percent aerosol former, and more preferably at least 70 weight percent aerosol former, on a dry weight basis. The gel composition may comprise up to 80 weight percent aerosol former. The aerosol former in the gel composition is preferably glycerol.

[0218] The gel composition preferably includes at least one gelling agent in a total amount ranging from about 0.4 weight percent to about 10 weight percent, or from about 0.5 weight percent to about 8 weight percent, or from about 1 weight percent to about 6 weight percent, or from about 2 weight percent to about 4 weight percent, or from about 2 weight percent to about 3 weight percent.

[0219] The term "gelling agent" refers to a compound that, when homogeneously added in an amount of about 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture, forms a solid medium or support matrix leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond cross-linking gelling agents and ionic cross-linking gelling agents.

[0220] The term "hydrogen-bond cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links via hydrogen bonds.

[0221] The hydrogen-bond cross-linking gelling agent may comprise one or more of galactomannan, gelatin, agarose, or konjac gum, or agar. Preferably, the hydrogen-bond cross-linking gelling agent comprises agar.

[0222] The term "ionically cross-linking gelator" refers to a gelator that forms non-covalent or physical cross-links through ionic bonds.

[0223] The ionic cross-linking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. Preferably, the ionic cross-linking gelling agent may include low acyl gellan.

[0224] The gelling agent may comprise one or more biopolymers, which may be formed from polysaccharides.

[0225] Examples of biopolymers include gellan gum (natural gellan gum, low acyl gellan gum, high acyl gellan gum, and low acyl gellan gum are preferred), xanthan gum, alginate (alginic acid), agar, and guar gum. It may be preferable for the composition to include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include two biopolymers in substantially equal amounts by weight. The composition may also include three biopolymers in substantially equal amounts by weight.

[0226] The gel composition may further comprise a thickening agent. The thickening agent in combination with the hydrogen-bond cross-linking gelling agent and the ionic cross-linking gelling agent surprisingly appears to support a solid medium and maintain the gel composition even when the gel composition contains high levels of glycerol.

[0227] The term "thickener" refers to a compound that, when uniformly added in an amount of 0.3 percent by weight to a 50 percent by weight water / 50 percent by weight glycerol mixture at 25°C, increases the viscosity without resulting in the formation of a gel, and causes the mixture to remain in a fluid state or to remain fluid.

[0228] The gel composition preferably comprises a thickener in the range of about 0.2 weight percent to about 5 weight percent, or about 0.5 weight percent to about 3 weight percent, or about 0.5 weight percent to about 2 weight percent, or about 1 weight percent to about 2 weight percent.

[0229] The thickening agent may comprise one or more of xanthan gum, carboxymethylcellulose, microcrystalline cellulose, methylcellulose, gum arabic, guar gum, lambda carrageenan, or starch. Preferably, the thickening agent may comprise xanthan gum.

[0230] The gel composition may further comprise a divalent cation. Preferably, the divalent cation comprises calcium ions, such as calcium lactate in solution. The divalent cation (e.g., calcium ions) may aid in gel formation in compositions that include a gelling agent, such as an ionically crosslinking gelling agent. Ionic effects may aid gel formation. The divalent cation may be present in the gel composition in a range of about 0.1 to about 1 weight percent, or about 0.5 weight percent.

[0231] The gel composition may further comprise an acid. The acid may comprise a carboxylic acid. The carboxylic acid may comprise a ketone group. Preferably, the carboxylic acid may comprise a ketone group having less than about 10 carbon atoms, such as levulinic acid or lactic acid, or less than about 6 carbon atoms, or less than about 4 carbon atoms. Preferably, the carboxylic acid has three carbon atoms (such as lactic acid).

[0232] The gel composition preferably contains some water, as the gel composition is more stable if the composition contains some water.

[0233] Preferably, the gel composition comprises about 8 weight percent to about 32 weight percent water, or about 15 weight percent to about 25 weight percent water, or about 18 weight percent to about 22 weight percent water, or about 20 weight percent water.

[0234] Preferably, when a gel composition is used, the aerosol-forming substrate comprises a porous medium loaded with the gel composition. An advantage of a porous medium loaded with the gel composition is that the gel composition is retained within the porous medium, which may aid in the manufacture, storage, or transportation of the gel composition. This may help maintain the desired shape of the gel composition, particularly during manufacture, transportation, or use.

[0235] The term "porous" is used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material.

[0236] The porous medium can be any suitable porous material capable of holding or retaining the gel composition. Ideally, the porous medium can allow the gel composition to move within it. In certain embodiments, the porous medium comprises natural, synthetic, or semi-synthetic materials, or a combination thereof. In certain embodiments, the porous medium comprises a sheet material, a foam, or a fiber, e.g., loose fiber, or a combination thereof. In certain embodiments, the porous medium comprises a woven fabric, a nonwoven fabric, or an extruded material, or a combination thereof. Preferably, the porous medium comprises cotton, paper, viscose, PLA, or cellulose acetate, or a combination thereof. Preferably, the porous medium comprises a sheet material, e.g., cotton or cellulose acetate. In a particularly preferred embodiment, the porous medium comprises a sheet made from cotton fibers.

[0237] The porous media may be crimped or chopped. The porous media may be in the form of sheets, threads, or tubular elements.

[0238] The aerosol-forming substrate may be doped with a portion of plant material, for example tobacco material, so long as the aerosol-forming substrate content is less than 5 weight percent, preferably less than 35 weight percent.

[0239] The aerosol-forming substrate may include tobacco particles. In the context of the present invention, the term "tobacco particles" refers to particles of any plant material of the Nicotiana species. The term "tobacco particles" encompasses ground or powdered tobacco lamina, ground or powdered tobacco stems, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. In a preferred embodiment, the tobacco particles are substantially entirely derived from tobacco lamina. In contrast, isolated nicotine and nicotine salts, although compounds derived from tobacco, are not considered tobacco particles for purposes of the present invention and are not included in the proportion of particulate plant material.

[0240] The aerosol-forming substrate may comprise a plant material and an aerosol former. The plant material may be an alkaloid-containing plant material, more preferably a nicotine-containing plant material, and more preferably a tobacco-containing material.

[0241] Alkaloids are a class of natural nitrogen-containing organic compounds. They are mainly found in plants, but also in bacteria, fungi, and animals. Examples of alkaloids include, but are not limited to, caffeine, nicotine, theobromine, atropine, and tubocurarine. A preferred alkaloid is nicotine, which can be found in tobacco.

[0242] As used herein, the term "tobacco material" is used to describe any material containing tobacco, including, but not limited to, tobacco leaf, tobacco veins, tobacco stems, tobacco stems, tobacco dust, expanded tobacco, reconstituted tobacco material, and homogenized tobacco material.

[0243] As used herein, the term "flavoring agent" refers to a composition having organoleptic properties that provide a sensory experience to the user, for example, to enhance the flavor of the aerosol. Flavoring agents can be used, for example, to deliver a taste (taste), an odor (smell), or both taste and odor to the user upon inhaling the aerosol.

[0244] The aerosol-forming substrate may comprise, on a dry weight basis, an aerosol former content of at least 35 percent, a tobacco content of less than 35 percent, and 0.5 to 4 percent by weight of one or more carboxylic acids.The aerosol-forming substrate may comprise, on a dry weight basis, an aerosol former content of at least 35 percent, a tobacco content of less than 35 percent, 0.5 to 4 percent by weight of one or more carboxylic acids, and less than 4 percent by weight of nicotine.

[0245] The aerosol-forming substrate may be a solid aerosol-forming film having the composition shown in Table I below. [Table 1]

[0246] The solid aerosol-generating film is (1) mixing the ingredients shown in Table I with water with stirring to form a slurry; (2) casting a layer of the slurry onto a flat surface to form a film having a thickness of 600 to 1000 micrometers; (3) leaving the film on a flat surface to solidify; (3) drying the film by heating the film to 140 degrees Celsius for 8 minutes to form a solid aerosol-forming film.

[0247] The aerosol-forming substrate may also be a solid aerosol-forming film having the composition shown in Table I below, except that the fumaric acid may be partially or completely replaced by one or more other carboxylic acids. For example, the fumaric acid may be partially or completely replaced by one or more carboxylic acids selected from malic acid, maleic acid, lactic acid, and benzoic acid.

[0248] The aerosol-forming substrate may be provided in the form of a film or a gel.

[0249] The aerosol-forming substrate may be provided in the form of a film having a thickness of from about 0.1 millimeter to about 1 millimeter, preferably from about 0.05 millimeter to about 0.75 millimeter, more preferably from about 0.05 millimeter to about 0.5 millimeter, more preferably from 50 micrometer to 400 micrometer, more preferably from 100 micrometer to 200 micrometer.

[0250] The total mass of the aerosol-forming substrate in the aerosol-generating article may be from 200 milligrams to 400 milligrams, preferably from 240 milligrams to 340 milligrams, more preferably from 250 milligrams to 290 milligrams, more preferably from 260 milligrams to 280 milligrams.

[0251] The portion of the aerosol-generating article filled with the aerosol-forming substrate may be referred to as the aerosol-forming substrate portion.

[0252] The aerosol-forming substrate portion may define a substantially cylindrical shape, and the cylindrical shape of the aerosol-forming substrate portion may have a diameter in the range of about 3 mm to about 10 mm, preferably about 6 mm to about 8 mm, and more preferably about 6.5 mm to about 7.5 mm.

[0253] The aerosol-generating article may comprise one or more susceptor elements. The one or more susceptor elements may be contained within the aerosol-forming substrate portion. For example, one or more elongated susceptor elements may be disposed substantially longitudinally within the aerosol-forming substrate portion and in thermal contact with the aerosol-forming substrate.

[0254] As used herein, the terms "susceptor" and "susceptor element" refer to an element that heats when subjected to an alternating magnetic field. This may be the result of eddy currents induced in the susceptor element, hysteresis losses, or both eddy currents and hysteresis losses. During use, the susceptor element is positioned in thermal contact or thermal proximity with an aerosol-forming substrate received within an aerosol-generating device or cartridge. In this manner, the aerosol-forming substrate is heated by the susceptor, thereby forming an aerosol.

[0255] The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. Preferred susceptor elements comprise metal or carbon.

[0256] Preferred susceptor elements may include or consist of a ferromagnetic material, such as a ferromagnetic alloy, ferritic iron, or ferromagnetic steel or stainless steel, etc. Suitable susceptor elements may be or include aluminum.

[0257] Suitable susceptor elements may include a non-metallic core having a metal layer, such as a metal band formed on the surface of the ceramic core. The susceptor element may have a protective outer layer, such as a protective ceramic or glass layer, encapsulating the susceptor element. The susceptor element may include a protective coating formed of glass, ceramic, or an inert metal formed over a core of susceptor element material.

[0258] The susceptor element may be disposed in thermal contact with the aerosol-forming substrate of the aerosol-forming substrate portion in which the susceptor element is incorporated. Thus, as the temperature of the susceptor element increases, the aerosol-forming substrate is heated and an aerosol is formed. Preferably, the susceptor element is disposed in direct physical contact with the aerosol-forming substrate, for example, within the aerosol-forming substrate.

[0259] The aerosol-forming substrate portion may include a susceptor element. The susceptor element may be at least partially surrounded by the aerosol-forming substrate. The susceptor element may be completely surrounded by the aerosol-forming substrate. The susceptor element may extend along substantially the entire length of the aerosol-forming substrate portion. This may provide optimized heat distribution within the aerosol-forming substrate when the susceptor element is heated. The susceptor element may comprise a flat, planar portion. The susceptor element may be a flat, planar susceptor strip. The susceptor element may comprise a metal or an alloy. The susceptor element may comprise aluminum.

[0260] As used herein, the term "flat planar" refers to a generally cubic shape having a height that is significantly less than its width and length. For example, the width and length may each be at least twice the height of the cube. The height of a flat planar cube may also be referred to as the thickness of the susceptor element, or the thickness of the flat planar portion of the susceptor element.

[0261] The susceptor element may generally have a thickness of 0.01 millimeters to 2 millimeters, for example, 0.5 millimeters to 2 millimeters. In some embodiments, the susceptor element preferably has a thickness of 10 micrometers to 500 micrometers, more preferably 10 micrometers to 100 micrometers. The susceptor element may have a thickness of about 35 micrometers to about 85 micrometers. The susceptor element may have a thickness of about 45 micrometers to about 75 micrometers. The susceptor element may have a thickness of about 55 micrometers to about 65 micrometers.

[0262] The susceptor element may be an elongated susceptor disposed substantially longitudinally within the aerosol-forming substrate portion.

[0263] The term "elongated" when used to describe a susceptor element means that the susceptor element has a length dimension that is greater than its width dimension or its thickness dimension, for example, more than twice its width dimension or its thickness dimension.

[0264] The susceptor element may be disposed substantially longitudinally within the aerosol-forming substrate portion. This means that the length dimension of the elongated susceptor is disposed approximately parallel to the longitudinal axis of the aerosol-forming substrate, for example, within ±10 degrees of parallel to the longitudinal axis of the aerosol-forming substrate. The elongated susceptor may be positioned at a radially central position within the aerosol-forming substrate portion and may extend along the longitudinal axis of the aerosol-forming substrate portion.

[0265] The susceptor elements may be in the form of pins, rods, strips, or blades.

[0266] The susceptor elements may have a length of about 5 millimeters to about 15 millimeters, for example, about 6 millimeters to about 12 millimeters, more preferably about 8 millimeters to about 10 millimeters. The susceptor elements may have a length of about 11 millimeters.

[0267] The susceptor elements may have a width of at least about 1 millimeter, more preferably at least about 2 millimeters. Typically, the susceptor elements may have a width of up to 8 millimeters, preferably no more than about 6 millimeters.

[0268] When the susceptor element has a constant cross-section, for example, a circular cross-section, it can have a width or diameter of from about 1 millimeter to about 5 millimeters.

[0269] When the susceptor elements have the form of strips or blades, the strips or blades may have a rectangular cross section, preferably having a width of about 2 millimeters to about 8 millimeters, more preferably about 3 millimeters to about 6 millimeters. A susceptor element in the form of a strip of blade may have a width of about 4 millimeters.

[0270] The elongated susceptor may have a thickness of about 57 micrometers to about 63 micrometers. Even more preferably, the elongated susceptor may have a thickness of about 58 micrometers to about 62 micrometers. Most preferably, the elongated susceptor has a thickness of about 60 micrometers.

[0271] The aerosol-generating article may comprise a downstream section located downstream of the aerosol-forming substrate portion. The downstream section is preferably located immediately downstream of the aerosol-forming substrate portion. The downstream section of the aerosol-generating article preferably extends between the aerosol-forming substrate portion and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements, each of which is described in more detail within this disclosure.

[0272] The length of the downstream section may be at least 10 millimeters, or at least 20 millimeters, or at least 25 millimeters, or at least 30 millimeters.

[0273] The length of the downstream section may be less than 70 millimeters, or less than 60 millimeters, or less than 50 millimeters.

[0274] For example, the length of the downstream section can be between 20 millimeters and 70 millimeters, or between 25 millimeters and 60 millimeters, or between 30 millimeters and 50 millimeters.

[0275] The downstream section of the aerosol-generating article according to the present invention preferably comprises a hollow tubular cooling element provided downstream of the aerosol-forming substrate portion, which may advantageously provide the aerosol cooling element for the aerosol-generating article.

[0276] The hollow tubular cooling element may be provided immediately downstream of the aerosol-forming substrate portion. In other words, the hollow tubular cooling element may abut the downstream end of the aerosol-forming substrate portion. The hollow tubular cooling element may define the upstream end of the downstream section of the aerosol-generating article. The downstream end of the aerosol-generating article may coincide with the downstream end of the downstream section. In some embodiments, the downstream section of the aerosol-generating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element. In other embodiments, the downstream section comprises two or more hollow tubular elements, as described below.

[0277] As used throughout this disclosure, the term "hollow tubular element" generally refers to an elongated element that defines a lumen or airflow passage along its longitudinal axis. In particular, the term "tubular" is used hereinafter with reference to a tubular element that has a substantially cylindrical cross-section and defines at least one airflow conduit that establishes uninterrupted fluid communication between the upstream end of the tubular element and the downstream end of the tubular element. However, it will be appreciated that alternative shapes of the tubular element (e.g., alternative cross-sectional shapes) may be possible. A hollow tubular cooling element may be an individual, separate element of an aerosol-generating article, having a defined length and thickness.

[0278] In the context of the present invention, a hollow tubular cooling element provides an unrestricted flow channel, which means that the hollow tubular cooling element provides a negligible resistance to withdrawal (RTD). The term "negligible RTD" is used to indicate an RTD of less than 1 millimeter of water column per 10 millimeters of hollow tubular cooling element length, preferably less than 0.4 millimeters of water column per 10 millimeters of hollow tubular cooling element length, and more preferably less than 0.1 millimeters of water column per 10 millimeters of hollow tubular cooling element length.

[0279] Preferably, the RTD of the hollow tubular cooling element is 10 mm water column or less, or 5 mm water column or less, or 2.5 mm water column or less, or 2 mm water column or less, or 1 mm water column or less.

[0280] The RTD of the hollow tubular cooling element can be at least 0 millimeters of water column, or at least 0.25 millimeters of water column, or at least 0.5 millimeters of water column, or at least 1 millimeter of water column.

[0281] In an aerosol-generating article according to the present invention, the overall RTD of the article depends essentially on the RTD of the rod and, optionally, the RTD of downstream and / or upstream elements, since the hollow tubular cooling element is substantially empty and therefore makes only a substantially small contribution to the overall RTD of the aerosol-generating article.

[0282] Therefore, the flow channels should not include any components that would impede the longitudinal air flow. It is preferred that the flow channels are substantially empty, and it is particularly preferred that the flow channels are empty.

[0283] As described in more detail herein, the aerosol-generating article may include ventilation zones at locations along the downstream section. In some embodiments, the aerosol-generating article may include ventilation zones at locations along the hollow tubular cooling element. These or any ventilation zones may extend through the peripheral wall of the hollow tubular cooling element. In this manner, fluid communication is established between the flow channels internally defined by the hollow tubular cooling element and the external environment. Ventilation zones are described further herein.

[0284] The length of the hollow tubular cooling element can be at least 15 millimeters, or at least 20 millimeters, or at least 25 millimeters. The length of the hollow tubular cooling element can be less than 50 millimeters, or less than 45 millimeters, or less than 40 millimeters. For example, the length of the hollow tubular cooling element can be 15 millimeters to 50 millimeters, or 20 millimeters to 45 millimeters, or 20 millimeters to 40 millimeters, or 20 millimeters to 30 millimeters, or 25 millimeters to 40 millimeters.

[0285] The relatively long, hollow, tubular cooling element provides and defines a relatively long internal cavity within the aerosol-generating article and downstream of the aerosol-forming substrate portion. Providing an empty cavity downstream (preferably immediately downstream) of the aerosol-forming substrate enhances nucleation of aerosol particles generated by the substrate. Providing a relatively long cavity maximizes the benefits of such nucleation, thereby improving aerosol formation and cooling.

[0286] The wall thickness of the hollow tubular cooling element may be between 100 micrometers and 2 millimeters, or between 150 micrometers and 1.5 millimeters, or between 200 micrometers and 1.25 millimeters.

[0287] The hollow tubular cooling element preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

[0288] The hollow tubular cooling element can have an outer diameter of 5 millimeters to 10 millimeters, e.g., 5.5 millimeters to 9 millimeters, or 6 millimeters to 8 millimeters. In certain embodiments, the hollow tubular cooling element has an outer diameter of less than 7 millimeters.

[0289] The hollow tubular cooling element may have an inner diameter. Preferably, the hollow tubular cooling element has a constant inner diameter along the length of the hollow tubular cooling element. However, the inner diameter of the hollow tubular cooling element may vary along the length of the hollow tubular cooling element.

[0290] The hollow tubular cooling element may have an inner diameter of at least 2 millimeters. For example, the hollow tubular cooling element may have an inner diameter of at least 3 millimeters, at least 4 millimeters, or at least 5 millimeters.

[0291] Providing a hollow tubular cooling element with an inner diameter as set out above may advantageously provide the hollow tubular cooling element with sufficient stiffness and strength.

[0292] The hollow tubular cooling element may have an inner diameter of 10 millimeters or less. For example, the hollow tubular cooling element may have an inner diameter of 9 millimeters or less, 8 millimeters or less, or 7 millimeters or less.

[0293] Providing a hollow tubular cooling element with an inner diameter as set out above may advantageously reduce the resistance to drawing the hollow tubular cooling element.

[0294] The hollow tubular cooling element may have an inner diameter of 2 millimeters to 10 millimeters, 3 millimeters to 9 millimeters, 4 millimeters to 8 millimeters, or 5 millimeters to 7 millimeters.

[0295] The lumen or cavity of the hollow tubular cooling element may have any cross-sectional shape. The lumen of the hollow tubular cooling element may have a circular cross-sectional shape.

[0296] The hollow tubular cooling element may comprise a paper-based material. The hollow tubular cooling element may comprise at least one layer of paper. The paper may be a very stiff paper. The paper may be a crimped paper, such as crimped heat-resistant paper or crimped parchment paper.

[0297] Preferably, the hollow tubular cooling element may comprise cardboard. The hollow tubular cooling element may be a cardboard tube. The hollow tubular cooling element may be formed from cardboard. Advantageously, cardboard is a cost-effective material that provides a balance between being deformable to provide ease of insertion of an item into the aerosol generating device and being sufficiently rigid to provide proper engagement of the item with the interior of the device. Thus, a cardboard tube may provide adequate resistance to deformation or compression during use.

[0298] The hollow tubular cooling element can be a paper tube. The hollow tubular cooling element can be a tube formed from spirally wound paper. The hollow tubular cooling element can be formed from multiple layers of paper. The paper can have a basis weight of at least 50 grams per square meter, at least 60 grams per square meter, at least 70 grams per square meter, or at least 90 grams per square meter.

[0299] The hollow tubular cooling element may comprise a polymeric material. For example, the hollow tubular cooling element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular cooling element may comprise low-density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0300] When the hollow tubular cooling element comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of 2 to 4 and a total denier of 25 to 40.

[0301] Preferably, aerosol-generating articles according to the present invention comprise a ventilation zone located along the downstream section. More particularly, in those embodiments in which the downstream section comprises a hollow tubular cooling element, a ventilation zone may be provided along the hollow tubular cooling element. Alternatively or additionally, in those embodiments in which the downstream section comprises a downstream hollow tubular element, a ventilation zone may be provided along the downstream hollow tubular element.

[0302] Thus, a vented cavity is provided downstream of the aerosol-forming substrate portion, which offers several potential technical advantages. First, the inventors have found that one such vented hollow tubular cooling element provides particularly efficient cooling of the aerosol. Second, the inventors have surprisingly found that such rapid cooling of volatile species released upon heating of the aerosol-forming substrate enhances nucleation of aerosol particles.

[0303] A ventilation zone typically includes a plurality of perforations through the circumferential wall of the hollow tubular cooling element. Preferably, the ventilation zone includes at least one circumferential row of perforations. In some embodiments, the ventilation zone may include two circumferential rows of perforations. For example, the perforations may be formed online during the manufacture of the aerosol-generating article. Preferably, each circumferential row of perforations includes between 8 and 30 perforations.

[0304] Aerosol-generating articles according to the present invention may have a ventilation level of at least 40 percent. Increasing the ventilation level may increase the level of aerosol cooling. However, increasing the ventilation level may mean that less air enters the aerosol-generating article through the upstream end of the aerosol-generating article and then flows through the aerosol-forming substrate portion. The ventilation level may thereby be selected based on the desired temperature and composition of the aerosol delivered to the user.

[0305] The aerosol-generating article preferably has a breathability level of at least 45 percent, more preferably at least 50 percent, more preferably at least 60 percent, more preferably at least 70 percent.

[0306] Aerosol-generating articles according to the present invention may have breathability levels of 90 percent or less, more preferably 85 percent or less, more preferably 80 percent or less.

[0307] Therefore, aerosol-generating articles according to the present invention may have a breathability level of 45 to 90 percent, more preferably 45 to 85 percent, and even more preferably 45 to 80 percent. Aerosol-generating articles according to the present invention may have a breathability level of 50 to 90 percent, preferably 50 to 85 percent, and more preferably 50 to 80 percent. Aerosol-generating articles according to the present invention may have a breathability level of 60 to 90 percent, preferably 60 to 85 percent, and more preferably 60 to 80 percent. Aerosol-generating articles according to the present invention may have a breathability level of 70 to 90 percent, preferably 70 to 85 percent, and more preferably 70 to 80 percent.

[0308] For example, the aerosol-generating article may have a breathability level of about 75 percent.

[0309] As discussed in this disclosure, the downstream section may include a downstream filter segment. The downstream filter segment may extend to the downstream end of the downstream section. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article. The downstream filter segment may also be referred to as a mouth end filter.

[0310] The downstream filter segment may be located downstream of the hollow tubular cooling element, as described above, and may extend between the hollow tubular cooling element and the downstream end of the aerosol-generating article.

[0311] The downstream filter segment is preferably a solid plug, which may also be described as a "plain" plug, and is non-tubular. Thus, the filter segment preferably has a substantially uniform cross-section.

[0312] The downstream filter segment is preferably formed of a fibrous filter material. The fibrous filter material may be for filtering the aerosol generated from the aerosol-forming substrate. Suitable fibrous filter materials will be known to those skilled in the art. Particularly preferably, at least one downstream filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0313] In certain preferred embodiments, the downstream section comprises a single downstream filter segment. In alternative embodiments, the downstream section comprises two or more downstream filter segments axially aligned in end-to-end abutting relationship with one another.

[0314] The downstream filter segment may optionally include a flavoring agent, which may be provided in any suitable form, for example, the downstream filter segment may comprise one or more capsules, beads, or granules of flavoring agent, or one or more flavor-loaded threads or filaments.

[0315] The downstream filter segment preferably has a low particle filtration efficiency.

[0316] The downstream filter segment is preferably surrounded by plug wrap. The downstream filter segment is preferably non-vented so that air does not enter the aerosol-generating article along the downstream filter segment.

[0317] The downstream filter segment is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by a tipping wrapper.

[0318] The downstream filter segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The outer diameter of the downstream filter segment may be substantially the same as the outer diameter of the hollow tubular cooling element.

[0319] The outer diameter of the downstream filter segment can be between 5 and 10 millimeters, or between 5.5 and 9 millimeters, or between 6 and 8 millimeters. In certain embodiments, the outer diameter of the downstream filter segment is less than 7 millimeters.

[0320] Unless otherwise specified, the resistance to draw (RTD) of a component or aerosol-generating article is measured in accordance with ISO 6565-2015. RTD refers to the pressure required to force air through the entire length of the component. The terms "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw." Such terms generally refer to measurements in accordance with ISO 6565-2015 normally performed at a temperature of 22 degrees Celsius, a pressure of 101 kPa (approximately 760 Torr), and 60% relative humidity, with a volumetric flow rate of 17.5 milliliters per second at the output or downstream end of the measured component. Smoking conditions and smoking machine specifications are provided in ISO Standard 3308 (ISO 3308:2000). Conditioning and testing atmospheres are provided in ISO Standard 3402 (ISO 3402:1999).

[0321] Resistance to withdrawal (RTD) can be expressed in pressure units "millimeters of water column" (mmWG).

[0322] The resistance to drawing (RTD) of the downstream section may be at least 0 millimeters of water column. The RTD of the downstream section may be at least 3 millimeters of water column. The RTD of the downstream section may be at least 6 millimeters of water column. The RTD of the downstream section may be no greater than 12 millimeters of water column. The RTD of the downstream section may be no greater than 11 millimeters of water column. The RTD of the downstream section may be no greater than 10 millimeters of water column.

[0323] The resistance to draw (RTD) characteristics of the downstream section may be entirely or predominantly attributable to the RTD characteristics of the downstream filter segments of the downstream section. In other words, the RTD of the downstream filter segments of the downstream section may completely define the RTD of the downstream section.

[0324] The resistance to draw (RTD) of the downstream filter segment may be at least 0 millimeters of water column, or at least 3 millimeters of water column, or at least 6 millimeters of water column. The RTD of the downstream filter segment may be no more than 12 millimeters of water column, or no more than 11 millimeters of water column, or no more than 10 millimeters of water column.

[0325] As described above, the downstream filter segment can be formed from a fibrous filtration material. The downstream filter segment can be formed from a porous material. The downstream filter segment can be formed from a biodegradable material. The downstream filter segment can be formed from a cellulose material, such as cellulose acetate. For example, the downstream filter segment can be formed from a bundle of cellulose acetate fibers having 10-15 denier per filament. For example, the downstream filter segment can be formed from a relatively low density cellulose acetate tow, such as a cellulose acetate tow containing 12 denier fibers per filament.

[0326] The downstream filter segment may be formed of a polylactic acid-based material. The downstream filter segment may be formed of a bioplastic material, preferably a starch-based bioplastic material. The downstream filter segment may be fabricated by injection molding or extrusion. Bioplastic-based materials are advantageous because they can provide a downstream filter segment structure that is simple and inexpensive to manufacture due to a specific complex cross-sectional profile that may include multiple relatively large airflow channels extending through the downstream filter segment material, providing favorable RTD characteristics.

[0327] The length of the downstream filter segment can be at least 5 millimeters, or at least 10 millimeters. The length of the downstream filter segment can be less than 25 millimeters, or less than 20 millimeters. For example, the length of the downstream filter segment can be 5 millimeters to 25 millimeters, or 10 millimeters to 25 millimeters, or 5 millimeters to 20 millimeters, or 10 millimeters to 20 millimeters.

[0328] The downstream section may further comprise one or more additional hollow tubular elements.

[0329] In certain embodiments, the downstream section may comprise a hollow tubular support element upstream of the hollow tubular cooling element. Preferably, the hollow tubular support element abuts the downstream end of the aerosol-forming substrate portion. Preferably, the hollow tubular support element abuts the upstream end of the hollow tubular cooling element. Preferably, the hollow tubular support element and the hollow tubular cooling element are adjacent to each other and together provide a hollow tubular section within the downstream section.

[0330] The hollow tubular support element may be formed from any suitable material or combination of materials. For example, the support element may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the support element is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibers. In a preferred embodiment, the hollow tubular support element comprises a hollow acetate tube.

[0331] The hollow tubular support element preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

[0332] The hollow tubular support element can have an outer diameter of 5 to 10 millimeters, for example, 5.5 to 9 millimeters, or 6 to 8 millimeters. In a preferred embodiment, the hollow tubular support element has an outer diameter of less than 7 millimeters.

[0333] The hollow tubular support element may have a wall thickness of at least 1 millimeter, preferably at least 1.5 millimeters, and more preferably at least 2 millimeters.

[0334] The hollow tubular support element may have a length of at least 5 millimeters. Preferably, the support element has a length of at least 6 millimeters, more preferably at least 7 millimeters.

[0335] The hollow tubular support element may have a length of less than 15 millimeters. Preferably, the hollow tubular support element has a length of less than 12 millimeters, more preferably less than 10 millimeters.

[0336] In some embodiments, the hollow tubular support element has a length of 5 mm to 15 mm, preferably 6 mm to 15 mm, and more preferably 7 mm to 15 mm. In other embodiments, the hollow tubular support element has a length of 5 mm to 12 mm, preferably 6 mm to 12 mm, and more preferably 7 mm to 12 mm. In further embodiments, the support element has a length of 5 mm to 10 mm, preferably 6 mm to 10 mm, and more preferably 7 mm to 10 mm.

[0337] Alternatively or in addition to the hollow tubular support element, the downstream section may further comprise a downstream hollow tubular element downstream of the hollow tubular cooling element. The downstream hollow tubular element may be provided immediately adjacent to the hollow tubular cooling element. Alternatively and preferably, the downstream hollow tubular element is separated from the hollow tubular cooling element by at least one other component. For example, the downstream section may comprise a downstream filter segment between the hollow tubular cooling element and the downstream hollow tubular element.

[0338] The downstream hollow tubular element preferably extends to the downstream end of the downstream section. Thus, the downstream hollow tubular element preferably extends to the downstream end of the aerosol-generating article. When the downstream hollow tubular element extends to the downstream end of the aerosol-generating article, the downstream hollow tubular element may define a mouth-end cavity of the aerosol-generating article.

[0339] In certain embodiments, additional downstream hollow tubular elements may be provided such that the downstream section comprises two adjacent downstream hollow tubular elements downstream of the downstream filter segment.

[0340] The RTD of the downstream hollow tubular element may be 10 millimeters of water column or less, or 5 millimeters of water column or less, or 2.5 millimeters of water column or less, or 2 millimeters of water column or less. The RTD of the downstream hollow tubular element is preferably 1 millimeter of water column or less. The RTD of the downstream hollow tubular element may be at least 0 millimeters of water column, or at least 0.25 millimeters of water column, or at least 0.5 millimeters of water column, or at least 1 millimeter of water column.

[0341] Therefore, the air flow channel of the downstream hollow tubular element should not contain any components that would impede the longitudinal air flow. It is preferred that the flow channel is substantially empty, and it is particularly preferred that the flow channel is empty.

[0342] Preferably, the length of the downstream hollow tubular element may be at least 3 millimeters, more preferably at least 4 millimeters, more preferably at least 5 millimeters, more preferably at least 6 millimeters. The length of the downstream hollow tubular element is preferably less than 20 millimeters, more preferably less than 15 millimeters, more preferably less than 12 millimeters, more preferably less than 10 millimeters.

[0343] The lumen or cavity of the downstream hollow tubular element may have any cross-sectional shape. The lumen of the downstream hollow tubular element may have a circular cross-sectional shape.

[0344] The downstream hollow tubular element may comprise a paper-based material. The downstream hollow tubular element may comprise at least one paper layer. The paper may be very stiff paper. The paper may be crimped paper, such as crimped heat-resistant paper or crimped parchment paper. The downstream hollow tubular element may comprise cardboard. The downstream hollow tubular element may be a cardboard tube.

[0345] The downstream hollow tubular element can be a paper tube. The downstream hollow tubular element can be a tube formed from spirally wound paper. The downstream hollow tubular element can be formed from multiple layers of paper. The paper can have a basis weight of at least 50 grams per square meter, at least 60 grams per square meter, at least 70 grams per square meter, or at least 90 grams per square meter.

[0346] The downstream hollow tubular element may comprise a polymeric material. For example, the downstream hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The downstream hollow tubular element may comprise low-density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. Preferably, the downstream hollow tubular element comprises cellulose acetate tow. For example, in a preferred embodiment, the downstream hollow tubular element comprises a hollow acetate tube.

[0347] When the downstream hollow tubular element comprises cellulose acetate tow, the cellulose acetate tow may have a denier per filament of 2 to 4 and a total denier of 25 to 40.

[0348] If the downstream section further comprises an additional downstream hollow tubular element as described above, the additional downstream hollow tubular element may be formed from the same material as the downstream hollow tubular element, or from a different material.

[0349] In certain preferred embodiments, the downstream section may include a ventilation zone at the location of the downstream hollow tubular element. In one example, this ventilation zone at the location of the downstream hollow tubular element may be provided in place of the ventilation zone at the location of the hollow tubular cooling element. In another example, the ventilation zone at the location of the downstream hollow tubular element may be provided in addition to the ventilation zone provided at the location of the hollow tubular cooling element.

[0350] A ventilation zone at a location along the downstream hollow tubular element may include a plurality of perforations through the circumferential wall of the downstream hollow tubular element. Preferably, a ventilation zone at a location along the downstream hollow tubular element includes at least one circumferential row of perforations. In some embodiments, a ventilation zone may include two circumferential rows of perforations. For example, the perforations may be formed online during manufacture of the aerosol-generating article. Preferably, each circumferential row of perforations includes between 8 and 30 perforations.

[0351] The aerosol-generating article may comprise one or more hollow tubular elements. The one or more hollow tubular elements may form part of a downstream section of the aerosol-generating article disposed downstream of the aerosol-forming substrate portion. The one or more hollow tubular elements may comprise one or both of hollow acetate tubing (HAT) and fine hollow acetate tubing (FHAT). Such hollow tubes may be made from cellulose acetate and are cylindrical components provided with a centrally disposed axial hole. The dimensions of the hollow tube, such as the outer diameter of the hollow tube and the outer diameter or diameter of the hole, may vary and can be designed according to the requirements of each product.

[0352] The HAT may have a length of 6 to 10 millimeters, preferably 7 to 9 millimeters, and more preferably about 8 millimeters. The HAT may be disposed downstream of the aerosol-forming substrate portion, preferably downstream of and directly abutting the aerosol-forming substrate portion. The HAT may function as one or more of an airflow cooling element and an airflow accelerating element.

[0353] The FHAT may be disposed downstream of the HAT, preferably downstream of and directly abutting the HAT. The inner diameter of the FHAT may be larger than the inner diameter of the HAT. For example, the inner diameter of the FHAT may be approximately twice the inner diameter of the HAT. The FHAT may function as an airflow slowdown element.

[0354] The aerosol-generating article may include a mouth-end filter. The mouth-end filter may be disposed downstream of the aerosol-forming substrate portion. The mouth-end filter may be disposed at the proximal end of the aerosol-generating article. The mouth-end filter may be disposed downstream of the FHAT and may directly abut the FHAT.

[0355] The mouth end filter may include a filter material. The filter material may be a filament material, such as cellulose acetate. The denier per filament may be 12. The denier of the filter material may be 12Y28.

[0356] The length of the mouth end filter along the longitudinal axis of the aerosol-generating article may be between 10 mm and 14 mm, preferably between 11 mm and 13 mm, and more preferably about 12 mm.

[0357] The withdrawal resistance of the mouth-end filter may be 1 to 100 millimeters of water column, preferably 2 to 50 millimeters of water column, more preferably 5 to 40 millimeters of water column, more preferably 10 to 30 millimeters of water column, more preferably 16 to 20 millimeters of water column, more preferably 17 to 19 millimeters of water column, and more preferably about 18 millimeters of water column. The withdrawal resistance of the mouth-end filter per millimeter of length along the longitudinal direction of the aerosol-generating article may be 0.1 to 20 millimeters of water column, preferably 0.2 to 10 millimeters of water column, more preferably 0.5 to 5 millimeters of water column or more, more preferably 1 to 2 millimeters of water column or more, more preferably 1.3 to 1.7 millimeters of water column, more preferably 1.4 to 1.6 millimeters of water column, and more preferably about 1.5 millimeters of water column.

[0358] The aerosol-generating article according to the present disclosure further comprises an upstream section located upstream of the aerosol-forming substrate portion. The upstream section is preferably located immediately upstream of the aerosol-forming substrate portion. The upstream section preferably extends between the upstream end of the aerosol-generating article and the aerosol-forming substrate portion. The upstream section comprises one or more upstream elements located upstream of the aerosol-forming substrate portion.

[0359] The aerosol-generating article of the present invention preferably comprises an upstream element located upstream of and adjacent to the aerosol-forming substrate portion. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-forming substrate portion. Furthermore, the presence of the upstream element helps to prevent any loss of the substrate, which can be advantageous, for example, when the substrate contains particulate plant material.

[0360] Where the upstream segment of the aerosol-forming substrate portion includes shredded tobacco, such as tobacco cut filler, the upstream section or element thereof may additionally help to prevent loss of loose particles of tobacco from the upstream end of the article, which may be particularly important, for example, when the shredded tobacco has a relatively low density.

[0361] The upstream element may be a porous plug element. Preferably, the upstream element has a porosity of at least 50 percent along the longitudinal axis of the aerosol-generating article. More preferably, the upstream element has a porosity of between 50 percent and 90 percent along the longitudinal axis. The porosity of the upstream element along the longitudinal axis is defined as the ratio of the cross-sectional area of ​​the material forming the upstream element to the internal cross-sectional area of ​​the aerosol-generating article at the location of the upstream element.

[0362] The upstream element may be made of a porous material or may include a plurality of openings, which may be achieved, for example, by laser drilling, and the plurality of openings are preferably uniformly distributed across the cross section of the upstream element.

[0363] The porosity or permeability of the upstream element may advantageously be designed to provide an aerosol-generating article with a particular overall resistance to draw (RTD) without substantially affecting the filtration provided by other portions of the article.

[0364] The upstream element may be formed from a material that is impermeable to air. In such embodiments, the aerosol-generating article may be configured such that suitable venting means provided in the wrapper allows air to enter the aerosol-forming substrate portion.

[0365] In certain preferred embodiments of the present invention, it may be desirable to minimize the RTD of the upstream element. For example, this may be the case for an article intended to be inserted into the cavity of an aerosol-generating device, such that the aerosol-forming substrate is externally heated, as described herein. For such articles, it is desirable to provide the article with the lowest possible RTD, so that the majority of the consumer's RTD experience is provided by the aerosol-generating device, rather than the article.

[0366] The RTD of the upstream element may be less than 30 millimeters of water column, or less than 20 millimeters of water column, or less than 10 millimeters of water column, or less than 5 millimeters of water column, or less than 2 millimeters of water column. The RTD of the upstream element may be at least 0.1 millimeters of water column, or at least 0.25 millimeters of water column, or at least 0.5 millimeters of water column. Preferably, the upstream element has an RTD of less than 2 millimeters of water column per millimeter of length, more preferably less than 1.5 millimeters of water column per millimeter of length, more preferably less than 1 millimeter of water column per millimeter of length, more preferably less than 0.5 millimeters of water column per millimeter of length, more preferably less than 0.3 millimeters of water column per millimeter of length, and more preferably less than 0.2 millimeters of water column per millimeter of length.

[0367] Preferably, the combined RTD of the upstream section or upstream element thereof and the aerosol-forming substrate portion is less than 15 mm of water column, more preferably less than 12 mm of water column, more preferably less than 10 mm of water column.

[0368] In certain preferred embodiments, the upstream element is formed of a solid, cylindrical plug element having a filled cross-section. Such a plug element may be referred to as a "plain" element. The solid plug element may be porous as described above, but does not have a tubular configuration and therefore does not provide a longitudinal flow channel. Preferably, the solid plug element has a substantially uniform cross-section.

[0369] In other preferred embodiments, the upstream element is formed from a hollow tubular segment defining a longitudinal cavity that provides an unrestricted flow channel. In such embodiments, the upstream element may provide protection for the aerosol-forming substrate, as described above, while having a minimal effect on the overall resistance to draw (RTD) and filtration characteristics of the article.

[0370] Preferably, the diameter of the longitudinal cavity of the hollow tubular segment forming the upstream element is at least 3 millimeters, more preferably at least 3.5 millimeters, more preferably at least 4 millimeters, more preferably at least 4.5 millimeters. Preferably, the diameter of the longitudinal cavity is maximized to minimize the RTD of the upstream section or upstream element thereof.

[0371] Preferably, the wall thickness of the hollow tubular segment is less than 2 millimeters, more preferably less than 1.5 millimeters, more preferably less than 1 millimeter.

[0372] The upstream element of the upstream section may be made of any material suitable for use in an aerosol-generating article. The upstream element may be made of the same material as that used in one of the other components of the aerosol-generating article, such as, for example, the downstream filter segment or a hollow tubular cooling element. Suitable materials for forming the upstream element include filter material, ceramic, polymeric material, cellulose acetate, cardboard, zeolite, or an aerosol-forming substrate. The upstream element may include a plug of cellulose acetate. The upstream element may comprise a hollow acetate tube or a cardboard tube.

[0373] The upstream element is preferably formed from a heat resistant material, for example, a material that can withstand temperatures up to 350 degrees Celsius, to ensure that the upstream element is not adversely affected by the heating means for heating the aerosol-forming substrate.

[0374] The upstream section or upstream element thereof preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article, and preferably has an outer diameter of between 5 mm and 8 mm, more preferably between 5.25 mm and 7.5 mm, and even more preferably between 5.5 mm and 7 mm.

[0375] Preferably, the upstream section or element has a length of 2 to 10 mm, more preferably 3 to 8 mm, more preferably 2 to 6 mm, In a particularly preferred embodiment, the upstream section or element has a length of 5 mm.

[0376] The upstream section is preferably surrounded by a component wrapper, such as plug wrap, which is preferably a stiff plug wrap, for example, a plug wrap having a basis weight of at least 80 grams per square meter, or at least 100 grams per square meter, or at least 110 grams per square meter, to provide structural rigidity to the upstream section.

[0377] The upstream section is preferably connected to the aerosol-forming substrate portion, and optionally to at least part of the downstream section, by an outer wrapper.

[0378] The aerosol-generating article may comprise an upstream section including a front plug. The front plug may be disposed upstream of the aerosol-forming substrate portion and may directly abut the aerosol-forming substrate portion. The front plug may be disposed at the distal end of the aerosol-generating article. The front plug may comprise a filter material. The length of the front plug along the longitudinal axis of the aerosol-generating article may be 1 to 10 mm, preferably 3 to 7 mm, more preferably 4 to 6 mm, and more preferably about 5 mm. The front plug may be in the form of a complete cylinder.

[0379] The front plug may have a withdrawal resistance of 1 to 150 mm of water column, preferably 1 to 50 mm of water column, more preferably 1 to 20 mm of water column, more preferably 1 to 10 mm of water column. The front plug may have a withdrawal resistance of about 10 mm of water column or less.

[0380] The front plug may help maintain the cleanliness of the aerosol-generating device by trapping slurry within the consumable. The front plug may prevent the aerosol-forming substrate or heating element from falling out of the aerosol-generating article.

[0381] Aerosol-generating articles according to the invention may have an overall length of at least 40 millimeters, or at least 50 millimeters, or at least 60 millimeters.

[0382] The overall length of an aerosol-generating article according to the present invention may be 90 millimeters or less, or 85 millimeters or less, or 80 millimeters or less.

[0383] In some embodiments, the total length of the aerosol-generating article is preferably 50 millimeters to 90 millimeters, more preferably 60 millimeters to 90 millimeters, and even more preferably 70 millimeters to 90 millimeters. In other embodiments, the total length of the aerosol-generating article is preferably 50 millimeters to 85 millimeters, more preferably 60 millimeters to 85 millimeters, and even more preferably 70 millimeters to 85 millimeters. In further embodiments, the total length of the aerosol-generating article is preferably 50 millimeters to 80 millimeters, more preferably 60 millimeters to 80 millimeters, and even more preferably 70 millimeters to 80 millimeters. In an exemplary embodiment, the total length of the aerosol-generating article is 75 millimeters.

[0384] In some embodiments, the total length of the aerosol-generating article is preferably between 40 millimeters and 70 millimeters, more preferably between 45 millimeters and 70 millimeters. In other embodiments, the total length of the aerosol-generating article is preferably between 40 millimeters and 60 millimeters, more preferably between about 45 millimeters and about 60 millimeters. In further embodiments, the total length of the aerosol-generating article is preferably between 40 millimeters and 50 millimeters, more preferably between 45 millimeters and 50 millimeters. In an exemplary embodiment, the total length of the aerosol-generating article is about 45 millimeters.

[0385] Preferably, the aerosol-generating article has an outer diameter of at least about 5 millimeters. More preferably, the aerosol-generating article has an outer diameter of at least 5.25 millimeters. Even more preferably, the aerosol-generating article has an outer diameter of at least 5.5 millimeters.

[0386] Preferably, the aerosol-generating article has an outer diameter of 8 millimeters or less. More preferably, the aerosol-generating article has an outer diameter of 7.5 millimeters or less. Even more preferably, the aerosol-generating article has an outer diameter of 7 millimeters or less.

[0387] The aerosol-generating article may have an outer diameter of 5 mm to 8 mm, or 5 mm to 7.5 mm, or 5 mm to 7 mm, or 5.25 mm to 8 mm, or 5.25 mm to 7.5 mm, or 5.25 mm to 7 mm, or 5.5 mm to 8 mm, or 5.5 mm to 7.5 mm, or 5.5 mm to 7 mm.

[0388] The outer diameter of the aerosol-generating article may be substantially constant along the entire length of the article. Alternatively, different portions of the aerosol-generating article may have different outer diameters.

[0389] Preferably, the overall RTD of the aerosol-generating article is at least 10 millimeters of water column. For example, the overall RTD of the aerosol-generating article may be at least 20 millimeters of water column, at least 30 millimeters of water column, at least 35 millimeters of water column, or at least 40 millimeters of water column.

[0390] The overall RTD of the aerosol-generating article may be 70 millimeters of water column or less. For example, the overall RTD of the aerosol-generating article may be 65 millimeters of water column or less, 60 millimeters of water column or less, or 55 millimeters of water column or less, or 50 millimeters of water column or less.

[0391] The overall RTD of the aerosol-generating article may be between 10 millimeters of water column and 70 millimeters of water column. For example, the overall RTD of the aerosol-generating article may be between 20 millimeters of water column and 65 millimeters of water column, between 30 millimeters of water column and 60 millimeters of water column, between 35 millimeters of water column and 55 millimeters of water column, or between 40 millimeters of water column and 50 millimeters of water column.

[0392] The aerosol-generating article may include vent holes. The vent holes may promote aerosol nucleation. The vent holes may assist in cooling the airflow. The vent holes may be provided within the FHAT. The FHAT may include 11 vent holes, each having a diameter of 0.11 millimeters.

[0393] The total draw resistance of the aerosol-generating article may be from 5 mm to 200 mm of water column, preferably from 10 mm to 150 mm of water column, more preferably from 20 mm to 100 mm of water column, more preferably from 80 mm to 80 mm of water column, more preferably from 40 mm to 60 mm of water column, more preferably from 45 mm to 55 mm of water column, more preferably about 48 mm of water column.

[0394] The aerosol-generating article may have a cylindrical shape.The aerosol-forming substrate portion may have a cylindrical shape.

[0395] The aerosol-generating article may comprise, from the proximal end to the distal end of the article, a mouth-end filter, one or more intermediate elements, an aerosol-forming substrate portion, and optionally a front plug. The one or more intermediate elements may include one or more of a HAT, a FHAT, and a PLA plug. The overall length of the article may be about 45 millimeters, and the length of the aerosol-forming substrate portion may be about 11 millimeters. The wrapper may surround the entire article or only a portion of it.

[0396] The present invention further relates to a package comprising a plurality of aerosol-generating articles, each aerosol-generating article in the package being an aerosol-generating article as described herein.

[0397] The present invention further relates to an aerosol generation system comprising an aerosol-generating article as described herein and an aerosol-generating device. The aerosol-generating device may include a cavity configured to at least partially insert the aerosol-generating article into the cavity. The cavity may be a heating chamber. The aerosol-generating device may comprise an internal heating element arranged to be inserted into the aerosol-generating article when the aerosol-generating article is at least partially inserted into the heating chamber. The aerosol-generating device may comprise an inductor coil. The inductor coil may at least partially surround the periphery of the heating chamber. The inductor coil may be arranged to coaxially surround the heating chamber. The inductor coil may be arranged to inductively heat a susceptor element. The susceptor element may be part of the internal heating element of the aerosol-generating device. The susceptor element may be part of the aerosol-generating article. The inductor coil may be arranged to inductively heat a susceptor of the aerosol-generating article when the aerosol-generating article is at least partially inserted into the heating chamber.

[0398] As used herein, the term "aerosol-generating article" refers to an article comprising an aerosol-forming substrate capable of emitting a volatile compound capable of forming an aerosol. The aerosol-generating article may be disposable. An aerosol-generating article comprising an aerosol-forming substrate containing tobacco may be referred to herein as a tobacco stick.

[0399] As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-generating device may interact with one or both of an aerosol-generating article including the aerosol-forming substrate and a cartridge including the aerosol-forming substrate. In some examples, the aerosol-generating device may heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically operated aerosol-generating device may include an atomizer, such as an electric heater, for heating the aerosol-forming substrate to form an aerosol.

[0400] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device with an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of an aerosol-generating device with an aerosol-generating article. In an aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device work together to generate an aerosol.

[0401] As used herein, the term "tubular element" is used to mean an elongated element that defines a lumen or airflow passage along its longitudinal axis. Specifically, the term "tubular" is used herein to encompass any tubular element that has a substantially cylindrical cross-section and defines at least one airflow passage that establishes uninterrupted fluid communication between the upstream end of the tubular element and the downstream end of the tubular element. However, it will be appreciated that alternative geometric shapes for the tubular element may be possible.

[0402] As used herein, the terms "upstream" and "forward," as well as "downstream" and "rearward," are used to describe the relative positions of components or portions of components of an aerosol-generating article with respect to the direction of air flow through the aerosol-generating article during use. An aerosol-generating article according to the present invention has a proximal end from which aerosol exits the article during use. The proximal end of an aerosol-generating article may also be referred to as the mouth end or downstream end. The mouth end is downstream of the distal end. The distal end of an aerosol-generating article may also be referred to as the upstream end. Components or portions of components of an aerosol-generating article may be described as being upstream or downstream of one another based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article. The forward side of a component or portion of a component of an aerosol-generating article is the portion at the end closest to the upstream end of the aerosol-generating article. The rearward side of a component or portion of a component of an aerosol-generating article is the portion at the end closest to the downstream end of the aerosol-generating article.

[0403] As used herein, the term "longitudinal" refers to a direction corresponding to the major longitudinal axis of the aerosol-generating article extending between the upstream and downstream ends of the aerosol-generating article.

[0404] The term "length" refers to the dimension of a component of an aerosol-generating article in its longitudinal direction. For example, it may be used to refer to the dimension of a rod or elongated tubular element in its longitudinal direction.

[0405] As used herein in connection with the present invention, the term "transverse" is used to describe a direction perpendicular to the longitudinal axis. Unless otherwise specified, a "cross section" of an aerosol-generating article or a component of an aerosol-generating article refers to a cross section.

[0406] As used herein, the term "proximal" refers to the user or mouth end of the aerosol-generating article, and the term "distal" refers to the end opposite the proximal end.

[0407] Components of an aerosol-generating article according to the present invention may be described as being upstream or downstream of one another based on their relative location between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article.

[0408] An aerosol-generating device suitable for use with the aerosol-generating articles described herein may comprise a cavity for receiving at least a portion of the aerosol-generating article, and a heater for heating the aerosol-forming substrate portion of the aerosol-generating article when the aerosol-generating article is received within the cavity. The cavity may be a heating chamber.

[0409] At least 25 percent of the length of the downstream section may be inserted or received within the device cavity when the aerosol-generating article is received within the device. At least 30 percent of the length of the downstream section may be inserted or received within the device cavity when the aerosol-generating article is received within the device.

[0410] The aerosol-generating device may include a heater for heating the aerosol-generating article. The heater may be of any suitable type. In the present invention, the heater is preferably an external heater. Preferably, the heater externally heats the aerosol-forming substrate portion when the aerosol-generating article is received in the aerosol-generating device. Such an external heater may surround the aerosol-generating article when inserted or received in the aerosol-generating device.

[0411] In some embodiments, the heater is arranged to be inserted into the aerosol-forming substrate when the aerosol-forming substrate is received within the cavity.

[0412] The heater may be located within the device cavity or heating chamber.

[0413] The heater may include at least one heating element. The at least one heating element may be any suitable type of heating element. In some embodiments, the device includes only one heating element. In some embodiments, the device includes multiple heating elements.

[0414] The heater may include a resistive heating arrangement.

[0415] In some embodiments, the heater comprises an induction heating arrangement. The induction heating arrangement may comprise an inductor coil and a power source configured to provide a high-frequency oscillating current to the inductor coil. As used herein, high-frequency oscillating current means an oscillating current having a frequency of about 500 kHz to about 30 MHz. The heater may advantageously comprise a DC / AC inverter for converting DC current provided by a DC power source into alternating current. The inductor coil may be arranged to generate a high-frequency oscillating electromagnetic field upon receiving the high-frequency oscillating current from the power source. The inductor coil may be positioned to generate a high-frequency oscillating electromagnetic field within the device cavity. In some embodiments, the inductor coil may substantially surround the device cavity. The inductor coil may extend at least partially along the length of the device cavity.

[0416] The heater may include an induction heating element. The induction heating element may be a susceptor element. The susceptor element may be arranged so that when an aerosol-generating article is received within the cavity of the aerosol-generating device, an oscillating electromagnetic field generated by the inductor coil induces a current in the susceptor element, heating the susceptor element. In these embodiments, the aerosol-generating device is preferably capable of generating a fluctuating electromagnetic field having a magnetic field strength (H-field strength) of 1 to 5 kiloamperes per meter (kA / m), preferably 2 to 3 kA / m, e.g., about 2.5 kA / m. Electrically operated aerosol generators are preferably capable of generating a fluctuating electromagnetic field having a frequency of 1 to 30 MHz, e.g., 1 to 10 MHz, e.g., 5 to 7 MHz.

[0417] In these embodiments, the susceptor element is preferably positioned in contact with the aerosol-forming substrate. In some embodiments, the susceptor element is positioned within the aerosol-generating device. In these embodiments, the susceptor element may be positioned within a cavity. The aerosol-generating device may include only one susceptor element. The aerosol-generating device may include multiple susceptor elements. In some embodiments, the susceptor element is preferably arranged to heat the outer surface of the aerosol-forming substrate.

[0418] The susceptor element may be part of an aerosol-generating device. The susceptor element may be part of an aerosol-generating article.

[0419] The susceptor element of the device may comprise any suitable material as described above in relation to the susceptor element incorporated within the aerosol-forming substrate portion.

[0420] In use, the heater can be controlled to operate within a defined operating temperature range that is less than the maximum operating temperature. The operating temperature range within the heating chamber (or device cavity) is preferably from about 150 degrees Celsius to about 300 degrees Celsius. The operating temperature range of the heater may be from about 150 degrees Celsius to about 250 degrees Celsius.

[0421] The aerosol generating device may include a power source. The power source may be a DC power source. In some embodiments, the power source is a battery. The power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery (e.g., a lithium-cobalt, lithium iron phosphate, or lithium polymer battery). However, in some embodiments, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for the storage of sufficient energy for one or more user operations, such as one or more aerosol generation experiences.

[0422] The following provides a non-exhaustive list of non-limiting examples, any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein. [Example]

[0423] Example 1: An aerosol-generating article comprising: an aerosol-forming substrate having a pH value of less than 5 and containing an aerosol former content of at least 5 weight percent on a dry weight basis; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 2: 10. The aerosol-generating article of claim 1, wherein the aerosol-forming substrate comprises a total aerosol-former content of at least 10 weight percent, preferably at least 15 weight percent, more preferably at least 20 weight percent, more preferably at least 25 weight percent, more preferably at least 30 weight percent, more preferably at least 35 weight percent, more preferably at least 40 weight percent, more preferably at least 45 weight percent, more preferably at least 50 weight percent, and more preferably at least 55 weight percent on a dry weight basis. Example 3: 3. The aerosol-generating article of any one of Examples 1 to 2, wherein the aerosol-forming substrate comprises nicotine, one or more cellulosic agents, one or more aerosol formers, and one or more carboxylic acids. Example 4: 4. The aerosol-generating article of any one of Examples 1 to 3, wherein the aerosol-forming substrate comprises, on a dry weight basis, from 0.1 weight percent to 8 weight percent of one or more carboxylic acids, preferably from 0.1 weight percent to 6 weight percent, more preferably from 0.5 weight percent to 4 weight percent, more preferably from 1.5 weight percent to 4 weight percent, more preferably from 2 weight percent to 4 weight percent. Example 5: 5. An aerosol-generating article according to any one of Examples 1 to 4, wherein the aerosol-forming substrate comprises one or more carboxylic acids that are free of non-carboxylic hydroxyl groups. Example 6: 6. An aerosol-generating article according to any one of Examples 1 to 5, wherein the aerosol-forming substrate comprises nicotine and one or more carboxylic acids, and the molar ratio of total carboxylic acids to nicotine is from 0.5:1 to 5:1, preferably from 1:1 to 4:1, more preferably from 2:1 to 3.5:1, more preferably from 0 to 0.3, more preferably from 0 to 0.2, more preferably from 0 to 0.1. Example 7: 7. An aerosol-generating article according to any one of Examples 1 to 6, wherein the aerosol-forming substrate comprises one or more carboxylic acids, the one or more carboxylic acids being selected from fumaric acid, maleic acid, and malic acid, preferably the one or more carboxylic acids being selected from fumaric acid and maleic acid, more preferably the one or more carboxylic acids being fumaric acid. Example 8: 8. The aerosol-generating article of any one of Examples 1 to 7, wherein the aerosol-forming substrate comprises, on a dry weight basis, from 0.5 to 5 weight percent, preferably from 0.5 to 3 weight percent, more preferably from 1 to 2 weight percent fumaric acid. Example 9: 9. The aerosol-generating article of any one of Examples 1 to 8, wherein the aerosol-forming substrate comprises, on a dry weight basis, from 0.5 to 5 weight percent maleic acid, preferably from 0.5 to 3 weight percent, and more preferably from 1 to 2 weight percent. Example 10: An aerosol-generating article according to any one of Examples 1 to 9, wherein the aerosol-forming substrate comprises one or both of fumaric acid and maleic acid, and the total amount of fumaric acid and maleic acid contained in the aerosol-forming substrate is 0.5 to 5 weight percent, preferably 0.5 to 3 weight percent, and more preferably 1 to 2 weight percent, on a dry weight basis. Example 11: 11. The aerosol-generating article of any one of Examples 1 to 10, wherein the aerosol-forming substrate comprises, on a dry weight basis, less than 6 weight percent, preferably less than 4 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent malic acid. Example 12: the aerosol-forming substrate comprises one or more carboxylic acids selected from acetic acid, benzoic acid, lactic acid and levulinic acid, or 12. An aerosol-generating article according to any one of Examples 1 to 11, wherein the aerosol-forming substrate does not contain a carboxylic acid selected from acetic acid, benzoic acid, lactic acid, and levulinic acid. Example 13: 13. An aerosol-generating article according to any one of Examples 1 to 12, wherein the aerosol-forming substrate has a total cellulosic agent content of 35 weight percent to 50 weight percent. Example 14: 14. An aerosol-generating article according to any one of Examples 1 to 13, wherein the aerosol-forming substrate comprises one or more cellulosic film-forming agents selected from carboxymethylcellulose and hydroxypropylmethylcellulose. Example 15: 15. An aerosol-generating article according to any one of Examples 1 to 14, wherein the aerosol-forming substrate comprises one or more cellulosic reinforcing agents selected from cellulose fibers, microcrystalline cellulose, and cellulose powder. Example 16: 16. An aerosol-generating article according to any one of Examples 1 to 15, wherein the aerosol-forming substrate is a solid aerosol-forming film, preferably the solid aerosol-forming film remains solid when heated to a temperature of from 180 degrees Celsius to 350 degrees Celsius. Example 17: An aerosol-generating article according to any one of Examples 1 to 16, wherein the aerosol-forming substrate is provided in the form of a film or a gel. Example 18: 18. The aerosol-generating article of Example 17, wherein the aerosol-forming substrate is provided in the form of a film having a thickness of from about 0.1 millimeter to about 1 millimeter, preferably from about 0.05 millimeter to about 0.75 millimeter, more preferably from about 0.05 millimeter to about 0.5 millimeter, more preferably from 50 micrometer to 400 micrometer, more preferably from 100 micrometer to 200 micrometer. Example 19: An aerosol-generating article according to any one of Examples 1 to 18, wherein the total weight of the aerosol-forming substrate in the aerosol-generating article is 200 milligrams to 400 milligrams, preferably 240 milligrams to 340 milligrams, more preferably 250 milligrams to 290 milligrams, more preferably 260 milligrams to 280 milligrams. Example 20: 20. The aerosol-generating article according to any one of Examples 1 to 19, wherein the aerosol-forming substrate does not contain tobacco. Example 21: 21. An aerosol-generating article according to any one of Examples 1 to 20, wherein the wrapper has a calcium carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent, and more preferably no calcium carbonate. Example 22: An aerosol-generating article according to any one of Examples 1 to 21, wherein the combined content of calcium carbonate and magnesium carbonate in the wrapper is less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent; more preferably the wrapper contains neither calcium carbonate nor magnesium carbonate. Example 23: An aerosol-generating article according to any one of Examples 1 to 22, wherein the wrapper has an alkali metal carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent, and more preferably is metal carbonate-free. Example 24: An aerosol-generating article as described in Example 23, wherein the wrapper has a metal carbonate content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent, and more preferably contains no metal carbonate. Example 25: and more preferably, the wrapper has a total content of filler materials selected from one or more of China clay, calcium carbonate, talc, titanium dioxide, starch, calcium sulfate, gypsum (calcium sulfate dihydrate), barium sulfate, magnesium carbonate, bentonite, aluminum hydroxide (alumina hydrate), silicates or silicate minerals such as silicate pigments, and zinc pigments of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent; 25. The aerosol-generating article of any of Examples 1-24, wherein the wrapper does not contain any filler material selected from china clay, calcium carbonate, talc, titanium dioxide, starch, calcium sulfate, gypsum (calcium sulfate dihydrate), barium sulfate, magnesium carbonate, bentonite, aluminum hydroxide (alumina hydrate), silicates or silicate minerals such as silicate pigments, and zinc pigments. Example 26: An aerosol-generating article as described in Example 25, wherein the wrapper has a total filler material content of less than 40 weight percent, preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent, and more preferably no filler material. Example 27: 27. An aerosol-generating article according to any one of Examples 1 to 26, wherein the ratio of the weight percentage of calcium carbonate to other fillers contained in the wrapper is 0 to 10, preferably 0 to 1, more preferably 0 to 0.5, more preferably 0 to 0.3, more preferably 0 to 0.2, more preferably 0 to 0.1. Example 28: An aerosol-generating article according to any one of Examples 1 to 27, wherein the ratio of calcium carbonate to titanium dioxide contained in the wrapper is 0 to 10, preferably 0 to 1, more preferably 0 to 0.5, more preferably 0 to 0.3, more preferably 0 to 0.2, more preferably 0 to 0.1. Example 29: An aerosol-generating article described in any of Examples 1 to 28, wherein the wrapper comprises one or more fillers other than calcium carbonate, and the sum of the weight percentages of the one or more fillers other than calcium carbonate in the wrapper is at least equal to the weight percentage of calcium carbonate in the wrapper. Example 30: 29. The aerosol-generating article of any one of Examples 1 to 29, wherein the wrapper comprises titanium dioxide, and the weight percentage of titanium dioxide in the wrapper is at least equal to the weight percentage of calcium carbonate in the wrapper. Example 31: 31. An aerosol-generating article according to any one of Examples 1 to 30, wherein the wrapper comprises at least 5 weight percent titanium dioxide, preferably at least 10 weight percent, more preferably at least 15 weight percent, more preferably at least 20 weight percent, more preferably at least 25 weight percent, more preferably at least 30 weight percent, more preferably at least 35 weight percent, more preferably at least 40 weight percent. Example 32: An aerosol-generating article according to any one of Examples 1 to 31, wherein the wrapper has a pH value of less than 7.8 or the wrapper has a pH value of greater than 8. Example 33: An aerosol-generating article according to any one of Examples 1 to 32, wherein the wrapper forms the outermost layer of the aerosol-generating article. Example 34: An aerosol-generating article according to any one of Examples 1 to 33, wherein there is no intermediate layer of material between the wrapper and the aerosol-forming substrate. Example 35: 35. The aerosol-generating article of Example 34, wherein the wrapper is in direct physical contact with the aerosol-forming substrate. Example 36: An aerosol-generating article according to any one of Examples 1 to 35, wherein the wrapper has a basis weight of from 30 grams per square meter to 100 grams per square meter, preferably from 50 grams per square meter to 90 grams per square meter, and more preferably from 60 grams per square meter to 80 grams per square meter. Example 37: An aerosol-generating article according to any one of Examples 1 to 36, wherein the thickness of the wrapper is from 50 micrometers to 90 micrometers, preferably from 60 micrometers to 80 micrometers, more preferably from 65 micrometers to 75 micrometers. Example 38: 38. An aerosol-generating article according to any one of Examples 1 to 37, wherein the wrapper has a basis weight of 55 grams per square meter to 65 grams per square meter, a thickness of 65 micrometers to 75 micrometers, and the wrapper does not contain a filler. Example 39: An aerosol-generating article comprising: an aerosol-forming substrate comprising one or more acids, preferably organic acids, more preferably organic carboxylic acids; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 40: An aerosol-generating article comprising: an aerosol-forming substrate comprising one or more acids selected from fumaric acid, maleic acid, malic acid, acetic acid, benzoic acid, lactic acid, and levulinic acid; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 41: An aerosol-generating article comprising: an acidic aerosol-forming substrate having a pH value of less than 7; a wrapper at least partially surrounding the aerosol-forming substrate; 1. An aerosol-generating article, wherein the wrapper comprises alkaline paper having a pH value greater than 7 and a calcium carbonate content of less than 45 weight percent. Example 42: An aerosol-generating article comprising: an aerosol-forming substrate comprising nicotine, one or more cellulosic agents, one or more aerosol formers, and one or more carboxylic acids; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 43: An aerosol-generating article comprising: an aerosol-forming substrate provided in the form of a film or gel; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 44: An aerosol-generating article comprising: an aerosol-forming substrate comprising an aerosol former content of at least 5 weight percent on a dry weight basis, an acid content of at least 1 weight percent on a dry weight basis, and a tobacco content of less than 75 weight percent on a dry weight basis, preferably less than 70 weight percent, more preferably less than 65 weight percent, more preferably less than 60 weight percent, more preferably less than 55 weight percent, more preferably less than 50 weight percent, more preferably less than 45 weight percent, more preferably less than 40 weight percent, more preferably less than 35 weight percent, more preferably less than 30 weight percent, more preferably less than 25 weight percent, more preferably less than 20 weight percent, more preferably less than 15 weight percent, more preferably less than 10 weight percent, more preferably less than 5 weight percent, more preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, and more preferably less than 1 weight percent; a wrapper at least partially surrounding the aerosol-forming substrate; An aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 percent by weight. Example 45: An aerosol generating system comprising an aerosol-generating article according to any one of Examples 1 to 44 and an aerosol generating device having a cavity configured to at least partially insert the aerosol-generating article into the cavity, preferably the cavity being a heated chamber.

[0424] Features described with respect to one embodiment may be equally applied to other embodiments of the invention.

[0425] 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]

[0426] [Figure 1] 1a and 1b show an aerosol-generating article. DETAILED DESCRIPTION OF THE INVENTION

[0427] FIG. 1a shows an aerosol-generating article in cross section. The article of FIG. 1a comprises a mouth-end filter 10, a fine hollow acetate tube 38, a hollow acetate tube 40, an aerosol-forming substrate portion 16 containing an aerosol-forming substrate, and a front plug 42. The aerosol-forming substrate has a pH value of less than 5 and an aerosol-forming substance content of at least 5 weight percent on a dry weight basis. The aerosol-forming substrate may be an aerosol-forming substrate as described herein. The mouth-end filter 10, the fine hollow acetate tube 38, and the hollow acetate tube 40 form a downstream section downstream of the aerosol-forming substrate portion 16. The front plug 42 forms an upstream section upstream of the aerosol-forming substrate portion 16.

[0428] The aerosol-forming substrate may comprise from 0.1 to 8 weight percent, more preferably from 0.1 to 6 weight percent, more preferably from 0.5 to 5 weight percent, more preferably from 1.5 to 4 weight percent, and more preferably from 2 to 4 weight percent of one or more carboxylic acids on a dry weight basis. Preferably, the one or more carboxylic acids are fumaric acid. The aerosol-forming substrate may have an aerosol former content of at least 35 weight percent on a dry weight basis. The aerosol-forming substrate may have a glycerin content of at least 35 weight percent on a dry weight basis. The aerosol-forming substrate may comprise a tobacco content of less than 75 weight percent on a dry weight basis, preferably less than 70 weight percent, more preferably less than 65 weight percent, more preferably less than 60 weight percent, more preferably less than 55 weight percent, more preferably less than 50 weight percent, more preferably less than 45 weight percent, more preferably less than 40 weight percent, and more preferably less than 35 weight percent.

[0429] Preferably, the aerosol-forming substrate comprises, on a dry weight basis, an aerosol former content of at least 35 percent, a tobacco content of less than 35 percent, and from 0.5 percent to 4 percent by weight of one or more carboxylic acids. More preferably, the aerosol-forming substrate comprises, on a dry weight basis, a glycerin content of at least 35 percent, a tobacco content of less than 35 percent, and from 0.5 percent to 4 percent by weight of one or more carboxylic acids. More preferably, the aerosol-forming substrate comprises, on a dry weight basis, a glycerin content of at least 35 percent, a tobacco content of less than 35 percent, and from 0.5 percent to 4 percent by weight of fumaric acid.

[0430] The aerosol-forming substrate may be provided in the form of a film or a gel.

[0431] The aerosol-forming substrate portion 16 may include an optional susceptor 20. The front plug 42 may be a filter plug. The distal portion of the article including the aerosol-forming substrate portion 16 is surrounded by a tipping wrapper 18, and the proximal portion is surrounded by a mouthpiece wrapper 44. The tipping wrapper has a calcium carbonate content of less than 45 weight percent.

[0432] A row of circumferential ventilation holes 46 is provided in the area where the mouthpiece wrapper 44 overlaps the tipping wrapper 18. The ventilation holes 46 may be provided in one or both of the fine hollow acetate tube 38, the mouthpiece wrapper 44, and the tipping wrapper 18.

[0433] The outer diameter of the article may be about 7 millimeters, preferably 7.1 millimeters. The overall length of the article may be about 45 millimeters. In one embodiment, the mouth-end filter 10 is about 12 millimeters long, the fine hollow acetate tubing 38 is about 9 millimeters long, the hollow acetate tubing 40 is about 8 millimeters long, the aerosol-forming substrate portion 16 is about 11 millimeters long, and the front plug 42 is about 5 millimeters long.

[0434] Figure 1b shows an aerosol-generating article in cross-section. The article of Figure 1b differs from the article of Figure 1a in that the article of Figure 1b includes an additional substrate wrapper 24 surrounding the aerosol-forming substrate portion 16. Furthermore, the optional susceptor 20 is not present in the embodiment of Figure 1b.

[0435] The substrate wrapper 24 may have a calcium carbonate content of less than 45 weight percent. In embodiments in which the calcium carbonate content of the substrate wrapper 24 is less than 45 weight percent, the tipping wrapper 18 may also have a calcium carbonate content of less than 45 weight percent, or may have any calcium carbonate content.

Claims

1. An aerosol-generating article comprising: an aerosol-forming substrate having a pH value of less than 5 and comprising an aerosol former content of at least 5 weight percent on a dry weight basis; a wrapper at least partially surrounding the aerosol-forming substrate, The aerosol-generating article, wherein the wrapper has a calcium carbonate content of less than 45 weight percent.

2. 10. The aerosol-generating article of claim 1, wherein the aerosol-forming substrate comprises a total aerosol-former content of at least 30 weight percent, more preferably at least 35 weight percent, more preferably at least 40 weight percent, more preferably at least 45 weight percent, more preferably at least 50 weight percent, more preferably at least 55 weight percent, on a dry weight basis.

3. 3. The aerosol-generating article of claim 1 or claim 2, wherein the aerosol-forming substrate comprises, on a dry weight basis, from 0.1 to 8 percent by weight of one or more carboxylic acids, preferably from 0.1 to 6 percent by weight, more preferably from 0.5 to 4 percent by weight, more preferably from 1.5 to 4 percent by weight, more preferably from 2 to 4 percent by weight.

4. 4. The aerosol-generating article of claim 1, wherein the aerosol-forming substrate comprises one or more carboxylic acids selected from fumaric acid, maleic acid, and malic acid, preferably the one or more carboxylic acids selected from fumaric acid and maleic acid, and more preferably the one or more carboxylic acids are fumaric acid.

5. 5. The aerosol-generating article according to claim 1, wherein the aerosol-forming substrate is provided in the form of a film or a gel.

6. 6. An aerosol-generating article according to any one of claims 1 to 5, wherein the aerosol-forming substrate has a tobacco content of less than 5 weight percent, preferably less than 4 weight percent, more preferably less than 3 weight percent, more preferably less than 2 weight percent, more preferably less than 1 weight percent, on a dry weight basis; more preferably the aerosol-forming substrate is tobacco-free.

7. 7. An aerosol-generating article according to any preceding claim, wherein the wrapper has a calcium carbonate content of less than 15 percent by weight, more preferably less than 10 percent by weight, more preferably less than 5 percent by weight, more preferably less than 4 percent by weight, more preferably less than 3 percent by weight, more preferably less than 2 percent by weight, more preferably less than 1 percent by weight, and more preferably is calcium carbonate-free.

8. 8. An aerosol-generating article according to any preceding claim, wherein the wrapper has a total content of filler material of less than 40% by weight, preferably less than 35% by weight, more preferably less than 30% by weight, more preferably less than 25% by weight, more preferably less than 20% by weight, more preferably less than 15% by weight, more preferably less than 10% by weight, more preferably less than 5% by weight, more preferably less than 4% by weight, more preferably less than 3% by weight, more preferably less than 2% by weight, more preferably less than 1% by weight, and more preferably no filler material.

9. 9. An aerosol-generating article according to any one of claims 1 to 8, wherein the ratio of calcium carbonate to titanium dioxide contained in the wrapper is from 0 to 10, preferably from 0 to 1, more preferably from 0 to 0.5, more preferably from 0 to 0.3, more preferably from 0 to 0.2, more preferably from 0 to 0.

1.

10. 10. The aerosol-generating article of any one of claims 1 to 9, wherein the wrapper comprises one or more fillers other than calcium carbonate, and the sum of the weight percentages of the one or more fillers other than calcium carbonate in the wrapper is at least equal to the weight percentage of calcium carbonate in the wrapper.

11. 11. The aerosol-generating article of any preceding claim, wherein the wrapper comprises titanium dioxide, and the weight percentage of titanium dioxide in the wrapper is at least equal to the weight percentage of calcium carbonate in the wrapper.

12. 12. An aerosol-generating article according to any preceding claim, wherein the wrapper comprises at least 5 weight percent titanium dioxide, preferably at least 10 weight percent, more preferably at least 15 weight percent, more preferably at least 20 weight percent, more preferably at least 25 weight percent, more preferably at least 30 weight percent, more preferably at least 35 weight percent, more preferably at least 40 weight percent.

13. 13. The aerosol-generating article of any preceding claim, wherein the wrapper has a pH value of less than 7.8 or wherein the wrapper has a pH value of greater than 8.

14. 14. An aerosol-generating article according to any preceding claim, wherein the wrapper forms the outermost layer of the aerosol-generating article at a longitudinal position where the wrapper surrounds the aerosol-forming substrate.

15. 15. An aerosol generation system comprising an aerosol-generating article according to any one of claims 1 to 14 and an aerosol generating device having a cavity configured to at least partially insert the aerosol-generating article into the cavity, preferably the cavity being a heated chamber.

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