RU2772453C2 - Aerosol generating product with isolated heat source - Google Patents

Abstract

FIELD: tobacco industry.

SUBSTANCE: group of inventions relates to an aerosol generating product and its formation method. The aerosol generating product contains aerosol forming substrate, a combustible heat source, at least one ceramic paper layer surrounding at least part of the length of the combustible heat source, where at least one ceramic paper layer contains a binder based on cellulose derivatives. Ceramic paper contains at least one of: bio-soluble fibers, fibers with low bio-persistency and fibers containing at least one of: silicon dioxide, calcium oxide and magnesium oxide.

EFFECT: reduced temperature of the surface near the heat source is provided; creation of the aerosol generating product is provided, which generates suitable aerosol both during the first puffs and during the last puffs.

13 cl, 6 dwg

Description

The present invention relates to an aerosol-generating article that contains an aerosol-generating substrate and a combustible heat source, and to a method for making such an aerosol-generating article.

The prior art provides a number of aerosol generating products in which tobacco is heated rather than burned. US 5,065,776 A describes a smoking article that includes a short carbonaceous combustible element in heat exchange communication with a physically separate aerosol generating means. In this case, an insulating wrapper formed from layers of tobacco and glass surrounds the combustible element. US 4,915,117 A describes a cigarette containing a thin sheet for retaining tobacco. Such a thin sheet is formed from a ceramic sheet by thermally decomposing a ceramic fiber woven or non-woven material at a high temperature at which no harmful substances are produced during heat generation when smoking a cigarette. Document RU 2236801 C2 describes a smoking article containing a wrapper that surrounds a tobacco smoking material, the wrapper containing a ceramic material. EP 245732 A2 describes a smoking article that is capable of producing a significant amount of aerosol without significant thermal decomposition of the substance to form an aerosol.

One of the purposes of such "heated" aerosol generating products is to reduce the levels of known harmful smoke constituents that result from the combustion and pyrolytic degradation of tobacco in combustible cigarettes. In a heated aerosol generating article of one known type, an aerosol is generated by the transfer of heat from a combustible heat source to an aerosol generating substrate that is adjacent to the combustible heat source. In aerosol generation, volatile compounds are released from the aerosol-generating substrate by heat transfer from a combustible heat source and are entrained in air drawn through the aerosol-generating article. When the released compounds are cooled, they condense to form an aerosol that is inhaled by the user.

The combustion temperature of a combustible heat source intended for use in an aerosol generating heated article should not be so high as to result in combustion or thermal degradation of the aerosol generating substrate during use of the aerosol generating heated article. However, the combustion temperature of the combustible heat source must be high enough to generate enough heat to release enough volatile compounds from the aerosol forming substrate to create a suitable aerosol, especially during the first puffs.

The prior art to which the present invention relates provides a number of combustible heat sources for use in aerosol generating heated articles. The combustion temperature of combustible heat sources for use in aerosol generating heated articles typically ranges from about 600°C to about 800°C.

It is known to wrap an insulating member around the periphery of a combustible heat source of an aerosol-generating heated article in order to reduce the surface temperature of the aerosol-generating heated article. However, it has been found that such insulating members can reduce the temperature of the combustible heat source during combustion of the combustible heat source, potentially reducing the efficiency of the heat source in heating the aerosol generating substrate to generate the aerosol. This effect is particularly noticeable when the insulating element substantially increases the length of the combustible heat source. Such insulating members can also prevent steady combustion of the combustible heat source, thereby reducing the burning time of the combustible heat source.

It would be desirable to provide an aerosol generating article that has a reduced surface temperature in the vicinity of a heat source, an acceptable appearance, and can be assembled easily and efficiently. It would also be desirable to provide an aerosol generating article that generates a suitable aerosol during both the first puffs and the last puffs.

According to a first aspect of the present invention, there is provided an aerosol generating article comprising an aerosol generating substrate, a combustible heat source, and at least one layer of ceramic paper surrounding at least a portion of the length of the combustible heat source. At least one layer of ceramic paper contains a cellulose derivative.

In use, the combustible heat source may be ignited by an external heat source such as a lighter and may start to burn. The combustible heat source can heat the aerosol-generating substrate, so that the volatile compounds of the aerosol-generating substrate are vaporized. When a user takes a puff on the aerosol-generating article, air may be drawn into the aerosol-generating article and mixed with vapor from the heated aerosol-generating substrate to form an aerosol. An aerosol may be drawn from an aerosol generating article and delivered to a user for inhalation by the user.

At least one layer of ceramic paper surrounding at least part of the length of the combustible heat source can insulate the combustible heat source. This can reduce the surface temperature of the aerosol generating article in the combustible heat source. The at least one layer of ceramic paper may also allow sufficient air to pass through the layer so as not to substantially impede the combustion of the combustible heat source.

In the context of this document, the term "paper" is used to describe a thin mat or sheet of fibers. Typically, the papers described herein are made from pulp compressed into a thin sheet or mat. The paper of the present invention may contain woven fibers. However, as a rule, the paper of the present invention contains non-woven fibers. The fibers of the paper of the present invention can be randomly interlaced. The types of paper described in this document are usually thin. In other words, the thickness or depth of the mat or sheet of fibers is substantially less than other dimensions of the mat or sheet, such as the length and width of the mat or sheet. As a rule, the types of paper described in this document are flexible. In other words, the papers described herein can be folded or shaped to wrap around the circumference of the combustible heat source such that the paper surrounds at least a portion of the combustible heat source.

In the context of this document, the term "ceramic paper" is used to describe paper containing a ceramic material. In other words, the term "ceramic paper" is used to describe a thin mat or sheet of fibers containing a ceramic material. In the context of this document, the terms "ceramic paper" and "ceramic fiber paper" are used interchangeably.

The ceramic paper of the present invention contains fibers of a ceramic material. The ceramic paper may contain woven fibers of the ceramic material. The ceramic paper may contain non-woven fibers of the ceramic material. The ceramic paper may comprise a fibrous ceramic material comprising at least one of ceramic fiber wadding, ceramic fiber wadding, and ceramic fiber wadding. In some embodiments, the implementation of the ceramic paper may contain only fibers of the ceramic material. In other words, in some embodiments, the implementation of ceramic paper may not contain fibers from non-ceramic material.

The ceramic paper may contain other forms of ceramic material, including particulate ceramic material. The ceramic paper may contain more than one form of ceramic material, such as fibrous ceramic material and particulate ceramic material.

The ceramic material may include any suitable ceramic material. The ceramic material may include crystalline ceramic materials. The ceramic material may include semi-crystalline ceramic materials. The ceramic material may include non-crystalline ceramic materials. The ceramic material may be amorphous. The ceramic material may be semi-crystalline. The ceramic material may be crystalline.

In the context of this document, the term "ceramic material" includes glasses. In the context of this document, the term "glass" is used to describe materials whose glass transition occurs at the glass transition temperature. Typically, the term "glass" in the context of this document is used to describe non-crystalline or amorphous solid materials. However, the term "glass" also includes materials containing crystalline components and non-crystalline components. Glass materials containing both crystalline and non-crystalline components may be referred to as "glass-ceramic" materials.

The properties of the glass materials of the present invention can be determined by the glass formation method. In the context of this document, the term "glass" includes glasses formed by any suitable method. Suitable methods for making glasses include: melt tempering; physical vapor deposition; solid phase reactions, including thermochemical and mechanochemical reactions; liquid phase reactions such as the sol-gel method; irradiation of crystalline solids, for example, radiation amorphization; as well as pressure amorphization (i.e. formation under high pressure).

In some embodiments, the implementation of the ceramic material may include glass. The ceramic material may be glass. The glass may be a glass-ceramic material. Ceramic paper may contain fiberglass. Ceramic paper may contain glass-ceramic fibers.

In some embodiments, the implementation of the ceramic material may not include glass. In other words, the ceramic material may include any ceramic material other than glasses. The ceramic material may not be a glass material. The ceramic material may not contain fiberglass. In these embodiments, the ceramic material typically includes crystalline ceramic materials.

The ceramic material may contain at least one of an oxide, a carbide, a boride, a nitride, and a silicide. For example, the ceramic material may contain a metal oxide. Ceramic paper may contain at least one of silicon dioxide (SiO ₂ ), calcium oxide (CaO), magnesium oxide (MgO), alumina (Al ₂ O ₃ ), and zirconia (ZrO ₂ ), all of which are considered ceramic materials. . For example, the ceramic paper may comprise at least one of alkaline earth metal silicate wadding, aluminosilicate wadding, or polycrystalline wadding. The ceramic paper may contain at least one of iron oxide (Fe ₂ O ₃ ), potassium oxide (K ₂ O), sodium oxide (Na ₂ O), all of which are considered ceramic materials.

The ceramic paper may contain any suitable amount of fibrous material. The ceramic paper may contain at least about 40 weight percent ceramic material; at least about 50 weight percent ceramic material, or at least about 60 weight percent ceramic material. The ceramic paper may contain less than about 99.99 weight percent ceramic paper material; or less than about 95 percent by weight of the ceramic material. For example, ceramic paper may contain from about 50 weight percent ceramic material to about 99.99 weight percent ceramic material.

Ceramic paper may contain non-fibrous material. The non-fibrous material may include water.

At least one layer of ceramic material according to the present invention contains a binder based on cellulose derivatives. Binders are used in some ceramic papers to hold the ceramic material together. Providing a binder can also improve the mechanical properties of the ceramic paper. For example, a binder can make ceramic paper less brittle and more flexible. This may advantageously allow at least one layer of ceramic paper to be wrapped around at least a portion of the combustible heat source.

In the context of this document, the term "cellulose derivative binder" is used to describe a binder containing a cellulose derivative. In particular, the cellulose derivative binder may contain a cellulose derivative that is created by adding a specific side group to the cellulose.

Suitable cellulose derivatives include, without limitation, carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEC), hydroxyethyl cellulose, cellulose acetate, cellulose ester, and cellulose ether. Preferably, the cellulose derivative binder contains carboxymethyl cellulose.

The cellulose derivative binder may be dispersed in a liquid, such as water, at a concentration of from about 0.01 percent by weight to about 20 percent by weight.

It has been found that the use of ceramic paper containing cellulose derivative binders advantageously holds the ceramic fibers together and provides the advantageous mechanical properties described above. In addition, it has been found that the use of ceramic paper containing cellulose derivative binders does not cause an unpleasant odor if a combustible heat source is ignited and burned.

At least one layer of ceramic paper may contain any amount of binder based on cellulose derivatives. At least one layer of ceramic paper may contain at least about 0.01 weight percent cellulose derivative binder, at least about 1 weight percent cellulose derivative binder, at least about 5 weight percent binder. cellulose derivatives or at least about 10 percent by weight of a cellulose derivative binder. In some embodiments, at least one ply of ceramic paper may contain no more than about 40 weight percent cellulose derivative binder, no more than about 30 weight percent cellulose derivative binder, or no more than about 15 weight percent binder. based on cellulose derivatives. At least one layer of ceramic paper may contain from about 0.01 weight percent to about 40 weight percent by weight of a binder based on cellulose derivatives. Ceramic paper may contain non-ceramic material. The non-ceramic material may include a polymeric material. The non-ceramic material may include organic material. The non-ceramic material may include an inorganic material.

Ceramic paper can be further reinforced by additional means such as particulate reinforcement. For example, ceramic paper can be reinforced with carbon black particles. The ceramic paper may further include any other suitable constituents, including, but not limited to, titanium dioxide, aluminum trihydrate, and pigments, which may contain iron and manganese.

The ceramic paper may contain any suitable amount of non-ceramic material. In some embodiments, the implementation of ceramic paper may contain only ceramic material. In other words, in some embodiments, the implementation of ceramic paper may not contain any non-ceramic materials. Ceramic paper may contain approximately 0 percent by weight of non-ceramic material. The ceramic paper may contain from 0 weight percent non-ceramic material to about 25 weight percent non-ceramic material. The ceramic paper may contain: at least about 0.5 percent by weight of a non-ceramic material; at least about 2 percent by weight non-ceramic material; at least about 10 percent by weight non-ceramic material; at least about 20 percent by weight non-ceramic material; at least about 30 percent by weight non-ceramic material; or at least about 40 weight percent non-ceramic material; or at least about 50 weight percent non-ceramic material. Ceramic paper may contain less than about 40 percent by weight of non-ceramic material; less than about 30 weight percent non-ceramic paper material; or less than about 15 weight percent non-ceramic material.

In some embodiments, the implementation of ceramic paper may contain fibers with low biopersistence. In some specific embodiments, the implementation of the fibrous material of the ceramic paper may consist of fibers with low biopersistence.

In the context of this document, the term "biopersistence" refers to the period of time during which the fiber remains unchanged in the lung and pleura (thorax) of the human respiratory system.

Suitable short term tests to measure biopersistence include short term inhalation experiments. An exemplary short term inhalation experiment involves exposing rodents to a specific fiber type at a known concentration for 6 hours per day for 5 days followed by periodic sacrifices to determine lung fiber loading. Such a procedure is described in Bernstein, D.M., C. Morscheidt, H.–G. Grimm, P. Thevenaz, and U. Teichert. 1996. Evaluation of soluble fibers using the inhalation biopersistence model, a nine–fiber comparison. Inhalation Toxicol. 8(4):345–385. Alternative suitable short term experiments to measure biopersistence include intratracheal infusion experiments involving dosing rodents by intratracheal infusion of a known amount of fiber in saline and intermittent sacrifices to determine lung fiber loading.

The results of both short term inhalation methods and intratracheal infusion methods can be expressed as the suspended matter elimination half-life (WT½) or as the time required to remove 90% of the fibers from the lung (T90).

Fibers may be considered "low biopersistence" or "low biopersistence" if a short-term inhalation biopersistence test demonstrates that fibers longer than 20 micrometers have a suspended solids half-life of 10 days or less, or a short-term biopersistence test by intratracheal infusion demonstrated that fibers longer than 20 micrometers have a suspended solids half-life of 40 days or less, as specified in Annex Q of European Commission Directive 97/69/EC of 5 December 1997. Fibers can also be considered as having "low biopersistence" or being "Low biopersistent" if the half-life after intratracheal infusion of 2 mg fine suspension for a fiber with a length of 5 μm, a diameter of less than 3 μm and a length to diameter ratio of more than 3:1 (WHO-fibres) is not more than 40 days to it, as specified in Annex Q2 of European Commission Decision 1999/836/EC of 26 October 1999 in relation to the national standards for mineral wool laid down by Germany derogating from Directive 97/69/EC.

Material with low biopersistence can be removed or cleared from the human respiratory system by a mechanism. One exemplary mechanism for removing material from the respiratory system is physical transport, such as by mucociliary transport. Another illustrative mechanism for removing material from the respiratory system is chemical dissolution. If the solubility of the material in the solvent present in the respiratory system is high enough, then the material can be considered "biosoluble".

In some embodiments, the implementation of ceramic paper may contain biosoluble fibers. In some specific embodiments, the implementation of the fibrous material of the ceramic paper may consist of biosoluble fibers.

In the context of this document, the term "biosoluble" is used to describe a material that is soluble in a biological system; in particular, it is used to describe a material that is soluble in the human respiratory system. The biosolubility of the material in the human respiratory system can differ significantly from the solubility of the material in water. In the context of this document, biosoluble fibers are considered to be fibers of low biopersistence.

For the purposes of this document, a substance may be considered "biosoluble" if the results of an in vitro static solubility test indicate that at least 0.1 g of the substance is soluble in 100 ml of solvent present in the human respiratory system. Similarly, a substance cannot be considered biosoluble if the results of a static dissolution test indicate that less than 0.1 g of the material is soluble in 100 ml of solvent present in the human respiratory system.

A suitable in vitro static dissolution test involves exposing a sample of the substance to be tested to a suitable solvent at 37° C. for 24 hours. After 24 hours, the degree of dissolution can be measured by determining the composition of the liquid for dissolution or the weight of the remaining sample. For example, elemental analysis using inductively coupled plasma mass spectrometry on a dissolution liquid can be used to calculate the total mass of a dissolved sample in the dissolution liquid.

Suitable solvents for use as the human respiratory solvent in in vitro static dissolution tests include physiological saline and human respiratory solvent surrogates such as known simulated lung fluids (SLFs). Known suitable SLFs include artificial lysosomal fluid (ALF) with a pH of approximately 4.5, similar to the fluid in which inhaled particles would come into contact after phagocytosis by alveolar and interstitial macrophages in the lung, and Gamble's solution with a pH of approximately 7.4, similar interstitial fluid deep in the lung.

For the purposes of this document, a substance may also be considered “biosoluble” if in vitro dynamic solubility tests indicate that the substance has a constant dissolution rate of at least 150 nanograms per square centimeter per hour (ng/cm² h) in solvent present in the human respiratory system.

Suitable in vitro dynamic dissolution tests include slowly flowing a suitable solvent through a sample of the test substance and measuring fiber dissolution over time. The test was carried out over a long period of time, such as at least three weeks, to determine whether the dissolution of the sample is uniform over a long period of time. More specifically, a suitable solvent is slowly pumped through the fiber sample, which has been normalized to its surface area, so that fresh solution is continuously supplied to the sample. A particular suitable in vitro dynamic dissolution test involves flowing a suitable solvent at 37 degrees Celsius through the sample to be tested at a rate of 5 ml per hour for a period of 1000 hours. The solution was collected and analyzed for the concentration of elements leached from the fiber sample. The solution was collected several times during the test period, for example twice a week, to determine if the dissolution of the sample is uniform or constant over time.

The degree of dissolution can be measured by determining the composition of the liquid for dissolution or the weight of the remaining sample. For example, elemental analysis using inductively coupled plasma mass spectrometry on a dissolution liquid can be used to calculate the total mass of a dissolved sample in the dissolution liquid at specific time intervals. Since the sample surface area and solvent consumption are known and the leachate concentration is determined from the dissolution measurements, these values can be used to determine the dissolution rate using known methods. The dissolution rate can be expressed in nanograms per square centimeter per hour (ng/cm²h).

Suitable solvents for use as the human respiratory solvent in in vitro dynamic dissolution testing include physiological saline and SLF as described above for in vitro static dissolution testing.

A specific suitable in vitro dynamic solubility test is described in BD Law, WB Bunn & TW Hesterberg (2008) Solubility of Polymeric Organic Fibers and Manmade Vitreous Fibers in Gambles Solution, Inhalation Toxicology, 2:4, 321–339, DOI: 10.3109/08958379009145261 .

The biosoluble material may be any suitable biosoluble material. Suitable biosoluble materials include alkaline earth metal silicate based materials and high alumina low silica materials.

In some preferred embodiments, the fibrous material comprises alkaline earth metal silicate fibers. In some particularly preferred embodiments, the implementation of the fibrous material essentially consists of fibers based on alkaline earth metal silicate. In some particularly preferred embodiments, the fibrous material is comprised of alkaline earth metal silicate fibers.

In some embodiments of the present invention, the ceramic paper may contain approximately 99.99 percent by weight of an alkaline earth metal silicate fibrous material, such as an alkaline earth metal silicate wadding.

In some embodiments of the present invention, the ceramic paper may comprise: from about 50 weight percent alkaline earth metal silicate fibrous material and about 99.99 weight percent alkaline earth metal silicate fibrous material.

In some embodiments of the present invention, the ceramic paper may contain from about 60 weight percent silica to about 70 weight percent silica; about 15 weight percent calcium oxide to about 35 weight percent calcium oxide; from about 4 weight percent magnesium oxide to about 20 weight percent magnesium oxide.

In some embodiments of the present invention, the ceramic paper may contain: less than about 40 weight percent alumina; less than about 10 weight percent organic material; and less than about 1 weight percent moisture.

The compositions indicated above refer to the percentage by weight of the various components after the combustion of the ceramic paper.

Examples of ceramic papers containing biosoluble ceramic fibers that are currently commercially available include: Superwool® Fiber Paper, Superwool® Fiber Flex Wrap, Superwool® HT Fiber, Superwool® Plus Fiber and Superwool® Plus 332-E; all of which are available from Morgan Advanced Materials, plc. Unbonded ceramic papers such as Rescor 300 BL from Final Advanced Materials, or DL-Thermal's unbonded biosoluble fibrous paper may also be suitable. Certain unbonded ceramic papers containing at least one of: biosoluble fibers may be suitable; fibers with low biopersistence; and fibers containing at least one of silicon dioxide, calcium oxide, and magnesium oxide. Certain unbonded ceramic papers containing alkaline earth metal silicate fibers may be suitable.

In some embodiments, the implementation of the ceramic paper may contain one or more of biosoluble fibers and fibers with low biopersistence. Examples of suitable materials that are at least one of biosoluble and low biopersistence include, but are not limited to, silica, calcium oxide, and magnesium oxide. Particularly suitable materials that are at least one of biosoluble and low biopersistence include alkaline earth metal silicates.

Ceramic paper may have low thermal conductivity. In other words, ceramic paper can be a good thermal insulator. For example, ceramic paper may have a thermal conductivity of about 0.5 to 2 W/mK at about 23°C. This low thermal conductivity is observed in particular if the ceramic paper contains a woven or non-woven fibrous ceramic material. This may be due to the relatively open, highly porous structure of the ceramic paper containing the fiber ceramic material, which reduces heat transfer by conduction.

Ceramic paper can have high air permeability. This may be due to the relatively open, highly porous structure. The at least one layer of ceramic paper may be sufficiently breathable to allow the combustion of the combustible heat source to be substantially unimpeded. For example, at least one layer of ceramic paper may have an air permeability greater than about 4000 (cm ³ /(min * cm ² ).

At least one layer of ceramic paper surrounds at least part of the length of the combustible heat source. At least one ceramic paper layer of the present invention may surround substantially the entire length of the combustible heat source. This can provide the aerosol generating product with the advantage of the insulating properties of the ceramic paper, the decrease in surface temperature near the heat source during use, and the advantage of the breathability of the ceramic paper, allowing sufficient ambient air to reach the combustible heat source so that the combustible heat source is substantially unobstructed. ignited and burned.

Ceramic paper may have advantageous mechanical properties. For example, ceramic paper may be flexible and machinable due to the reinforcing effect of the ceramic material, in particular ceramic fibers, if present. The ceramic paper may be machinable, which facilitates the formation of a layer of ceramic paper surrounding at least part of the length of the heat source.

In the context of this document, the term "layer" is used to describe a body of material, generally corresponding to the shape of a combustible heat source. The at least one layer of ceramic paper may be any suitable type of layer located around the circumference of the heat source. Suitable types of layers include but are not limited to wraps and covers. In the context of this document, the term "coating" is used to describe a layer of material that covers and adheres to a heat source.

At least one layer of ceramic paper may be in direct contact with a combustible heat source. At least one layer of ceramic paper may be located at a distance from the combustible heat source.

At least one layer of ceramic paper surrounds at least part of the length of the combustible heat source. For example, at least one layer of ceramic paper may surround approximately half the length of the combustible heat source. At least one layer of ceramic paper may surround more than half the length of the combustible heat source. The at least one layer of ceramic paper may surround from about 60 percent to about 100 percent of the length of the combustible heat source. At least one layer of ceramic paper may surround at least about 70 percent of the length of the combustible heat source. At least one layer of ceramic paper may surround at least about 80 percent of the length of the combustible heat source. At least one layer of ceramic paper may surround at least about 90 percent of the length of the combustible heat source. The at least one layer of ceramic paper may surround substantially the length of the combustible heat source.

At least one layer of ceramic paper may surround the entire length of the combustible heat source. In the context of this document, the term "length" is used to describe the size of a component or part of an aerosol generating article in the longitudinal direction of the aerosol generating article.

At least one layer of ceramic paper may surround approximately half the length of the aerosol forming substrate. Advantageously, the at least one layer of ceramic paper surrounding the aerosol generating substrate can lower the surface temperature of the aerosol generating article in the aerosol generating substrate.

The at least one layer of ceramic paper may surround the combustible heat source at the downstream end of the combustible heat source. This can advantageously reduce the surface temperature of the aerosol generating article in the part of the combustible heat source closest to the user during normal operation of the aerosol generating article.

The at least one layer of ceramic paper may surround the combustible heat source at the upstream end of the combustible heat source.

The at least one layer of ceramic paper may surround the combustible heat source at the upstream end and at the downstream end.

Uncovered parts of the combustible heat source may be referred to herein as "exposed" parts. At least one layer of ceramic paper of the present invention may be provided to cover or surround "exposed" or uncovered portions of the combustible heat source.

In some embodiments, a portion of the combustible heat source may be surrounded by at least one additional layer at the upstream end. At least one additional layer may be a cigarette paper layer. In these embodiments, the upstream portion of the combustible heat source is the exposed portion. In other words, the upstream portion of the combustible heat source is not covered by at least one additional layer. In these embodiments, at least one layer of ceramic paper may surround the upstream portion of the combustible heat source. At least one layer of ceramic paper may surround the combustible heat source from the upstream end of at least one additional layer surrounding the upstream portion of the combustible heat source to or around the downstream end of the combustible heat source. Thus, in these embodiments, the combustible heat source can be surrounded substantially along its length by a combination of at least one additional layer at the upstream end and at least one layer of ceramic paper at the upstream end. In some embodiments, at least one layer of ceramic paper and at least one additional layer may overlap along the length of the combustible heat source.

The combustible heat source, the aerosol generating substrate, and at least one layer of ceramic paper may be configured to substantially prevent or suppress the temperature of the aerosol generating substrate from rising above about 375° C. during combustion of the combustible heat source. For example, the combustible heat source, the aerosol-generating substrate, and at least one layer of ceramic paper can be selected in terms of shape, size, and location to substantially prevent or suppress the temperature of the aerosol-generating substrate from rising above about 375°C during burning time of a combustible heat source. This can preserve the integrity of the aerosol generating substrate. For example, if the aerosol-forming substrate contains one or more aerosol-forming agents, then the aerosol-forming materials may be pyrolyzed at temperatures above about 375°C. At even higher temperatures, and if the aerosol-forming substrate contains tobacco, for example, tobacco can burn.

The combustible heat source, the aerosol-forming substrate, and at least one layer of ceramic paper may be configured such that, when the combustible heat source is combusted, the temperature of the aerosol-forming substrate, 2 mm from the inner surface of the aerosol-forming substrate, is at least at least about 100°C for a period of at least about 6 minutes.

The at least one layer of ceramic paper may be of any suitable thickness. Typically, at least one layer of ceramic paper is a thin layer. The thickness of at least one layer of ceramic paper may be at least about 0.25 millimeters or at least about 0.5 millimeters. The thickness of at least one layer of ceramic paper may be less than about 10 millimeters or less than about 5 millimeters. The at least one layer of ceramic paper may have a thickness of from about 0.25 millimeters to about 10 millimeters, or from about 0.5 millimeters to about 5 millimeters.

The at least one ceramic paper layer may further comprise one or more air inlets, such as one or more perforations. The one or more air inlets may further increase the breathability of the at least one ceramic paper layer.

In some embodiments of the present invention, the aerosol generating article further comprises one or more airflow passages through which air can be drawn through the aerosol generating article for inhalation by the user. When a user takes a puff on the aerosol generating product, air may be drawn into the aerosol generating product along one or more airflow passages.

The at least one layer of ceramic paper may be separated from one or more airflow passages such that, in use, air drawn through the aerosol generating article along one or more airflow passages does not directly contact the at least one layer. ceramic paper.

In some embodiments, at least one layer of ceramic paper may be separated from one or more airflow passages such that air drawn through the aerosol generating article along one or more airflow passages does not directly contact at least one layer of ceramic paper.

In some embodiments, one or more portions of at least one layer of ceramic paper may be covered, coated, or encapsulated in a material substantially impervious to fibers and particles. One or more portions of at least one layer of ceramic paper that are closed, coated or encapsulated in a material substantially impervious to fibers and particles may be located proximate the air drawn through the aerosol generating article along one or more airflow passages. By closing, covering or sealing, it is possible to isolate the air drawn through the aerosol generating article along one or more airflow passages from the fibers and particles of the at least one layer of ceramic paper.

In some embodiments, one or more portions of at least one layer of ceramic paper may be covered with a layer of paper to isolate the at least one layer of ceramic paper from one or more airflow passages. The paper layer may be located on at least one of the inner surface of at least one ceramic paper layer and the outer surface of at least one ceramic paper layer. The paper layer may be located on both the inner and outer surfaces of at least one ceramic paper layer. The paper layer may comprise laminated paper. The paper layer may be in a multilayer configuration with at least one ceramic paper layer. The paper layer may be located only on a portion of at least one ceramic paper layer adjacent to the air flow passage.

The at least one layer of ceramic paper may be substantially flame resistant. In the context of this document, the term "burn-resistant" is used to describe a material that remains substantially intact during the ignition and combustion of a combustible heat source. Providing at least one layer of fire-resistant ceramic paper surrounding at least part of the length of the combustible heat source can advantageously prevent fire or smoke from being emitted from the layer. This can substantially prevent or suppress unwanted emissions or odors emitted from the bed when the combustible heat source is burned.

In some embodiments of the present invention, the aerosol generating article further comprises one or more non-combustible, substantially airtight baffles between the combustible heat source and the aerosol generating substrate. One or more non-combustible, substantially airtight baffles between the combustible heat source and the aerosol generating substrate isolate the combustible heat source from one or more air flow passages such that, in use, air drawn through the aerosol generating article along one or more passages for air flow, does not come into direct contact with a combustible heat source.

The aerosol generating article of the present invention comprises an aerosol generating substrate. In the context of this document, the term "aerosol-forming substrate" is used to describe a substrate that has the ability to release volatile compounds when heated, which can form an aerosol. The aerosols generated from the aerosol-forming substrates in the aerosol-generating articles of the present invention may be visible or invisible and may contain vapors (e.g., fine particles of substances in the gaseous state, which at room temperature are usually liquid or solid), as well as gases and liquid droplets of condensed vapors.

The aerosol forming substrate may be solid. The aerosol-forming substrate may be solid at room temperature.

The aerosol-forming substrate contains at least one aerosol-forming agent and at least one material capable of responding to heat by emitting volatile compounds.

The at least one aerosol generating agent may be any suitable known compound or mixture of compounds that, when used, promotes the formation of a dense and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the aerosol generating article. Suitable aerosol forming agents are well known in the art and include, for example, polyhydric alcohols, polyhydric alcohol esters such as glycerol mono-, di-, or triacetate, and aliphatic mono-, di-, or polycarboxylic acid esters, such as dimethyl dodecanedioate and dimethyltetradecanedioate. Exemplary aerosol generating agents for use in aerosol generating articles of the present invention are polyhydric alcohols or mixtures thereof such as triethylene glycol, 1,3-butanediol and glycerin.

The material capable of releasing volatile compounds in response to heating may be a plant material filler, such as a homogenized plant material filler. For example, an aerosol-forming substrate may comprise one or more plant-derived materials including, but not limited to: tobacco; tea, such as green tea; peppermint; laurel; eucalyptus; basil; sage; verbena and tarragon. The botanical material may contain additives including, but not limited to, humectants, flavors, binders, and mixtures thereof. The plant material may consist primarily of tobacco material, optionally of homogenized tobacco material.

The aerosol generating articles of the present invention may contain aerosol generating substrates containing nicotine. For example, the aerosol generating articles of the present invention comprise aerosol generating substrates containing tobacco.

The aerosol forming substrate may be surrounded by a filter ficell.

The aerosol generating article of the present invention comprises a combustible heat source positioned to heat the aerosol generating substrate and separated from one or more airflow passages.

The combustible heat source may comprise a body of combustible material. The combustible material body may have a substantially constant diameter. The combustible material body may have a constant diameter along its length. This can advantageously simplify the processes involved in the manufacture of a combustible heat source and an aerosol generating article. In some embodiments, the combustible material body may form a substantially circular cylindrical body having a substantially constant diameter along its length.

The combustible heat source may be a carbonaceous combustible heat source. In the context of this document, the term "carbonaceous" is used to describe a combustible heat source containing carbon. Preferably, the carbonaceous combustible heat sources for use in the aerosol generating articles of the present invention have a carbon content of at least about 35 percent, more preferably at least about 40 percent, most preferably at least about 45 percent, on a dry weight basis. 30 combustible heat source.

The combustible heat source according to the present invention may be a carbon-based combustible heat source. In the context of this document, the term "carbon-based heat source" is used to describe a heat source containing primarily carbon.

Carbon based combustible heat sources for use in aerosol generating articles of the present invention may have a carbon content of at least about 50 percent, preferably at least about 60 percent, more preferably at least about 70 percent, most preferably at least about 70 percent. at least about 80 percent based on the dry weight of the carbon-based combustible heat source.

The combustible heat source of the present invention is separate from one or more airflow passages through the aerosol generating article. In the context of this document, the term "airflow passage" is used to describe the route along which air can be drawn through an aerosol generating article for inhalation by a user. In the context of this document, the terms "upstream" and "downstream" are used to describe the relative directions and positions of the components of an aerosol generating article with respect to the direction of airflow through one or more airflow passages when a user puffs on aerosol generating product.

Isolating the combustible heat source from one or more airflow passages of the aerosol generating article can substantially prevent or suppress the activation of combustion of the combustible heat source during a puff performed by the user. This can substantially prevent or reduce the likelihood of peaks in the temperature of the aerosol forming substrate during puffs by the user. This can substantially prevent or suppress combustion or pyrolysis of the aerosol-forming substrate during heavy puffing patterns. This can substantially prevent or suppress changes in the composition of the aerosol generated by the aerosol generating article due to the user's puffing pattern.

Isolating the combustible heat source from one or more airflow passages can also substantially prevent or suppress combustion and decomposition products and other materials generated by ignition and combustion of the combustible heat source from entering air drawn through the aerosol generating article along one or more more passages for air flow.

The separated combustible heat source of the present invention may comprise a continuous heat source. In the context of this document, the term "continuous" is used to describe a combustible heat source in which air drawn through an aerosol generating article for inhalation by a user does not pass through airflow channels along the combustible heat source. As such, the heat exchange between the continuous combustible heat source and the aerosol-forming substrate occurs predominantly by conductive heat transfer.

Due to the absence of airflow channels through the combustible heat source, convective heat exchange between the combustible heat source and the aerosol-forming substrate is reduced or minimized. By reducing convective heat exchange between the combustible heat source and the aerosol-generating substrate, temperature spikes in the aerosol-generating substrate during a user puff can be substantially prevented or suppressed. This can substantially prevent or suppress combustion or pyrolysis of the aerosol-forming substrate during heavy puffing patterns. This can substantially prevent or suppress changes in the composition of the aerosol generated by the aerosol generating article due to the user's puffing pattern. It can also substantially prevent or suppress combustion and decomposition products and other materials generated by ignition and combustion of the combustible heat source from entering the air drawn through the aerosol generating article along one or more airflow passages.

The separated combustible heat source of the present invention may comprise a discontinuous heat source. In the context of this document, the term "discontinuous" is used to describe a heat source in which air drawn through an aerosol generating article for inhalation by a user passes through one or more airflow channels along the heat source. As such, heat exchange between the discontinuous combustible heat source and the aerosol-forming substrate may occur by both conductive heat exchange and convective heat exchange along one or more airflow channels.

In the context of this document, the term "airflow duct" is used to describe a duct running along the length of the combustible heat source through which air can be drawn in a downstream direction for inhalation by the user. As such, the aerosol generating article of the present invention may not include one or more airflow channels.

The one or more non-combustible, substantially airtight baffles between the combustible heat source and the aerosol generating substrate may include a first baffle that is adjacent to one or both of the proximal end of the combustible heat source and the distal end of the aerosol generating substrate. The first baffle may assist in isolating the combustible heat source from one or more airflow passages of the aerosol generating article. The first baffle can reduce the maximum temperature to which the aerosol generating substrate is exposed during ignition or combustion of the combustible heat source and can substantially prevent or suppress thermal degradation or combustion of the aerosol generating substrate during use of the aerosol generating article.

In the context of this document, the term "non-combustible" is used to describe a material that is essentially non-combustible at the temperatures reached by a combustible heat source during its combustion and ignition.

In the context of this document, the term "airtight" is used to describe a material that essentially prevents or inhibits the passage of air through it.

The first baffle may be adjacent to one or both of the proximal end of the combustible heat source and the distal end of the aerosol generating substrate. The first septum may be glued or otherwise attached to one or both of the proximal end of the combustible heat source and the distal end of the aerosol generating substrate.

The first baffle may include a first barrier coating provided on the inner surface of the combustible heat source. In such embodiments, the first baffle may comprise a first barrier coating provided on at least substantially the entire interior surface of the combustible heat source. The first baffle may include a first barrier coating provided over the entire inner surface of the combustible heat source. The first barrier coating may be formed and applied to the inner surface of the combustible heat source by any suitable method, such as those described in WO-A1-2013120855.

Depending on the desired properties and characteristics of the aerosol generating article, the first baffle may have a low thermal conductivity or a high thermal conductivity. In certain embodiments, the first baffle may have a thermal conductivity of from about 0.1 W/m⋅K to about 200 W/m⋅K.

The thickness of the first baffle can be suitably adjusted to provide good aerosol generation characteristics. In certain embodiments, the first septum may have a thickness of from about 10 microns to about 500 microns.

The first baffle may be made from one or more suitable materials that are substantially thermally stable and non-combustible at the temperatures reached by the combustible heat source during ignition and combustion. Suitable materials are known in the art and include, but are not limited to, clays (eg, such as bentonite and kaolinite), glasses, minerals, ceramics, resins, metals, and combinations thereof.

Materials from which the first baffle may be made include clays and glasses. More materials from which the first baffle can be made include copper, aluminium, stainless steel, alloys, aluminum oxide (Al ₂ O ₃ ), resins and mineral adhesives.

If the first baffle comprises a metal or alloy such as copper, aluminium, stainless steel, then the first barrier coating may advantageously act as a thermal bond between the combustible heat source and the aerosol generating substrate. This can improve conductive heat transfer from the combustible heat source to the aerosol generating substrate.

The aerosol generating article may further comprise one or more air inlets downstream of the proximal end of the combustible heat source. In some embodiments, one or more air inlets are located between the proximal end of the combustible heat source and the proximal end of the aerosol generating article. The one or more air inlets may be positioned such that air can be drawn into one or more airflow passages of the aerosol generating article through the one or more air inlets without being drawn through a combustible heat source. This can substantially prevent or suppress temperature spikes in the aerosol generating substrate during puffs by the user.

The one or more air inlets may include suitable air inlets through which air can be drawn into the aerosol generating article. For example, suitable air inlets include holes, slots, slots, or other openings. The number, shape, size and location of the air inlets can be suitably adjusted to provide good aerosol generating performance.

One or more air inlets may be located on the aerosol generating substrate. One or more air inlets may be located between the distal end of the aerosol generating substrate and the proximal end of the aerosol generating substrate. If one or more air inlets are located on the aerosol-forming substrate and the aerosol-forming substrate comprises a filter ficelle, then the filter ficelle may have one or more air inlets to pass air into the aerosol-forming substrate. The one or more openings may be slits, slots, or other suitable openings through which air may be drawn into the aerosol generating substrate. The number, shape, size and location of the openings can be suitably adjusted to provide good aerosol generation performance.

The combustible heat source may include one or more airflow channels. In other words, the combustible heat source may be a discontinuous combustible heat source. One or more air flow channels may extend along the length of the combustible heat source. The one or more airflow passages may form part of one or more airflow passages of the aerosol generating article.

If the combustible heat source comprises one or more airflow channels in the aerosol generating article, then one or more non-combustible, substantially airtight baffles between the combustible heat source and the aerosol generating substrate may further comprise a second baffle between the combustible heat source and one or more more channels for the air flow of the combustible heat source.

The second baffle may improve isolation of the combustible heat source from one or more airflow passages of the aerosol generating article. The second baffle may limit the maximum temperature to which the aerosol-generating substrate is exposed during ignition or combustion of the combustible heat source, and thus help prevent or reduce thermal degradation or combustion of the aerosol-generating substrate during use of the aerosol-generating article.

The second baffle may be glued or otherwise attached to the combustible heat source.

The second baffle may include a second barrier coating provided on the inner surface of one or more airflow channels. The second baffle may include a second barrier coating provided on at least substantially the entire inner surface of the one or more airflow channels. The second baffle may include a second barrier coating provided over the entire inner surface of the one or more airflow channels.

The second barrier coating may be provided by inserting a liner into one or more airflow channels. For example, if one or more airflow passages provide one or more airflow passages through the interior of the combustible heat source, then a non-combustible, substantially airtight hollow tube may be inserted into each of the one or more airflow passages.

The second baffle may advantageously substantially prevent or suppress the air drawn downstream along one or more airflow channels of combustion and decomposition products generated during the ignition and combustion of the combustible heat source of the aerosol generating articles of the present invention.

Depending on the desired properties and characteristics of the aerosol generating article, the second baffle may have a low thermal conductivity or a high thermal conductivity. The second baffle may have low thermal conductivity.

The thickness of the second septum can be suitably adjusted to provide good aerosol generating performance. In some embodiments, the second septum may have a thickness of from about 30 microns to about 200 microns. In one embodiment, the second septum has a thickness of from about 30 microns to about 100 microns.

The second baffle may be made from one or more suitable materials that are substantially thermally stable and non-combustible at the temperatures reached by the combustible heat source during ignition and combustion. Suitable materials are known in the art and include, without limitation, for example: clays; metal oxides such as iron oxide, alumina, titanium oxide, silicon dioxide, silica-alumina, zirconia and cerium oxide; zeolites; zirconium phosphate; and other ceramic materials or combinations thereof.

Materials from which the second baffle may be made include clays, glasses, aluminium, iron oxide, and combinations thereof. If desired, catalytic ingredients, such as ingredients that promote the oxidation of carbon monoxide to carbon dioxide, may be included in the second baffle. Suitable catalyst ingredients include, but are not limited to, for example, platinum, palladium, transition metals and their oxides.

If the aerosol generating articles of the present invention comprise a first baffle between the downstream end of the combustible heat source and the upstream end of the aerosol generating substrate, and a second baffle between the combustible heat source and one or more airflow channels along combustible heat source, the second baffle may be formed from the same material or materials as the first baffle or a different material or materials.

If the second baffle comprises a second barrier coating provided on the inner surface of the one or more airflow channels, then the second barrier coating may be applied to the inner surface of the one or more airflow channels by any suitable method, such as those described in US– A-5,040,551 and WO-A1-2013120855.

The aerosol generating article may further comprise one or more additional layers surrounding at least the proximal portion of the combustible heat source and the distal portion of the aerosol generating substrate. The one or more additional layers may comprise at least one of: a heat transfer element for transferring heat from a combustible heat source to an aerosol generating substrate; and a layer of cigarette paper.

The thermally conductive element may only surround the distal portion of the aerosol-forming substrate. The thermally conductive element may surround a substantially length of the aerosol forming substrate. The thermally conductive element may be in direct contact with at least one of a combustible heat source and an aerosol generating substrate. The thermally conductive element may not be in direct contact with both the combustible heat source and the aerosol generating substrate.

The heat transfer element may provide thermal communication between the combustible heat source and the aerosol generating substrate. The heat transfer element may be substantially flame resistant.

Suitable heat transfer elements may include: metal foil wraps or metal alloy foil wraps. Metal foil wraps can include: aluminum foil wraps, steel foil wraps, iron foil wraps, and copper foil wraps. The heat transfer element may comprise an aluminum tube.

The proximal part of the combustible heat source surrounded by the heat transfer element has a length of about 2 millimeters to about 8 millimeters, or a length of about 3 millimeters to about 5 millimeters.

The distal portion of the combustible heat source not surrounded by the heat transfer element has a length of about 4 millimeters to about 15 millimeters, or a length of about 4 millimeters to about 8 millimeters.

The cigarette paper layer may surround at least the proximal portion of the combustible heat source, the length of the aerosol generating substrate, and any other components of the aerosol generating article located proximate the aerosol generating substrate. The cigarette paper layer may surround substantially the length of the combustible heat source. If the cigarette paper layer surrounds a substantially length of the combustible heat source, then the cigarette paper layer may be provided with ventilation, such as perforations, holes, or slits, on the combustible heat source to allow air to pass through the cigarette paper layer to the combustible heat source. The number, shape, size and location of the holes can be suitably adjusted to provide good aerosol generation performance. The cigarette paper layer may be tightly wrapped around the combustible heat source and the aerosol generating substrate such that the cigarette paper layer captures and holds the combustible heat source and the aerosol generating substrate when the aerosol generating article is assembled.

At least one layer of ceramic paper may be a radially outer layer. If the aerosol generating article comprises one or more additional layers, then the radially outer ceramic paper layer may overlap at least a portion of the one or more additional layers. In other words, one or more additional layers may be located between the combustible heat source and at least one layer of ceramic paper. For example, if the aerosol generating article comprises an additional layer containing a heat transfer element, then the heat transfer element may be a radially inner layer, and at least one layer of ceramic paper may be a radially outer layer surrounding at least a portion of the heat transfer element.

In the context of this document, the terms "radially out" and "radially in" are used to indicate the relative distances of the components of the aerosol generating article from the longitudinal axis of the aerosol generating article. In the context of this document, the term "radial" is used to describe a direction perpendicular to the longitudinal axis of the aerosol generating article extending in the direction between the proximal end and the distal end of the aerosol generating article.

One or more additional layers may be radially outer layers. One or more additional layers may overlap at least a portion of at least one layer of ceramic paper.

At least one layer of ceramic paper may be fixed or attached to one or more other components or parts of the aerosol generating article. At least one layer of ceramic paper may be fixed to any suitable component of the aerosol generating article. For example, at least one layer of ceramic paper may be fixed to at least one of a combustible heat source, an aerosol generating substrate, and one or more additional layers. The at least one layer of ceramic paper may be fixed to one or more components of the aerosol generating article by any suitable means. At least one layer of ceramic paper can be fixed through the use of an adhesive. Suitable adhesives, such as silicate glue, may have high heat resistance. If one or more additional layers are radially outer layers, then one or more additional layers can be tightly wrapped around at least a portion of at least one layer of ceramic paper.

In some embodiments, the implementation of at least one layer of ceramic paper may be inseparable from the combustible heat source. In the context of this document, the term "inseparable" is used to describe a layer that is in direct contact with a combustible heat source and is attached to a combustible heat source without the aid of a foreign adhesive or other intermediate connecting material.

In some embodiments, at least one layer of ceramic paper may be formed from a strip of ceramic paper having opposite ends. A strip of ceramic paper may be wrapped around a combustible heat source such that opposite ends of the strip overlap. The overlapped opposite ends of the strip may be secured to each other by the use of an adhesive or any other suitable means. This can fix at least one layer of ceramic paper to the combustible heat source.

In some embodiments, an intermediate layer may be positioned between at least one layer of ceramic paper and at least one of a combustible heat source, an aerosol forming substrate, and one or more additional layers. The intermediate layer may be adjacent to at least one layer of ceramic paper. The intermediate layer may be in contact with at least one layer of ceramic paper. The intermediate layer may be located radially within at least one layer of ceramic paper.

The intermediate layer may be an adhesive layer. The adhesive layer may contain any suitable adhesive. Suitable adhesives, such as silicate glue, may have high heat resistance. The adhesive layer may be positioned between the at least one ceramic paper layer and the combustible heat source and may attach the at least one ceramic paper layer to the combustible heat source. The adhesive layer may be located between at least one layer of ceramic paper and one or more additional layers and may attach at least one layer of ceramic paper to one or more additional layers. The adhesive layer may be positioned between the at least one ceramic paper layer and the aerosol generating substrate and may attach the at least one ceramic paper layer to the aerosol generating substrate.

In some embodiments, at least one layer of ceramic paper may be formed from a strip of ceramic paper having opposite ends. A strip of ceramic paper may be wrapped around a combustible heat source such that opposite ends of the strip are butted but not overlapped. The adhesive layer may be on the side of the strip facing the combustible heat source, at least at opposite ends of the strip. The adhesive layer may attach the ceramic paper strip to a combustible heat source, at least at opposite ends of the strip.

The aerosol generating article may include a thermally conductive component positioned between the combustible heat source and the aerosol generating substrate. The thermally conductive component may be the first baffle as described above. The aerosol generating article may include a thermally conductive component and a first baffle. The thermally conductive component may be made of a material similar to that of the thermally conductive element. An aerosol generating article may include a thermally conductive component and a thermally conductive element. Providing at least one of a heat transfer element and a heat transfer component can improve conductive heat transfer between the combustible heat source and the aerosol generating substrate.

The aerosol generating article may additionally contain any other suitable components. For example, an aerosol generating article may comprise at least one of: a moving element; an aerosol cooling element; separating element; and mouthpiece. One or more additional components may be positioned coaxially with the combustible heat source and the aerosol generating substrate. One or more additional components may be located in the vicinity of the aerosol generating substrate. One or more additional components may be arranged in any suitable order. The aerosol generating article may further comprise: a transfer element adjacent to a proximal end of the aerosol generating substrate; an element that cools the aerosol adjacent to the proximal end of the moving element; a separating element adjacent to the proximal end of the aerosol cooling element; and a mouthpiece adjacent to the proximal end of the spacer element.

In the context of this document, the terms "near" and "far" are used to describe the relative positions of the components or parts of the components of the products that generate aerosol, according to the present invention. The proximal end of the aerosol generating article component is the end of that component closest to the mouth end of the aerosol generating article, and the distal end of the aerosol generating article component is the end of the component furthest from the mouth end , an aerosol generating product. Typically, a combustible heat source is located at the far end of the aerosol generating article.

According to a second aspect of the present invention, there is provided a method for forming an aerosol generating article according to the first aspect of the present invention. The method includes: positioning a combustible heat source for heating an aerosol-forming substrate; and surrounding at least part of the length of the combustible heat source with at least one layer of ceramic paper containing a binder based on cellulose derivatives.

In some embodiments, the step of surrounding at least a portion of the length of a combustible heat source with at least one layer of ceramic paper may include: providing a strip of ceramic paper containing a cellulose derivative binder having opposite ends; wrapping the strip around the combustible heat source such that the combustible heat source is surrounded by at least one layer of ceramic paper; overlapping opposite ends of the strip; and joining the overlapping ends to attach at least one layer of ceramic paper to a combustible heat source.

The overlapping ends of the ceramic paper strip may be secured to each other by any suitable means. For example, the overlapping ends of a ceramic paper strip can be bonded to each other using an adhesive. Suitable adhesives should have high temperature resistance and contain a silicate adhesive.

In some embodiments, the step of surrounding at least a portion of the length of a combustible heat source with at least one layer of ceramic paper may include: providing a strip of ceramic paper containing a cellulose derivative binder having opposite ends; applying an adhesive layer to one side of the strip, at least to each opposite end; the location of the strip with the adhesive layer facing the combustible heat source; wrapping the strip around the combustible heat source such that at least a portion of the length of the combustible heat source is surrounded by at least one layer of ceramic paper; joining opposite ends of the strip without overlapping opposite ends; and attaching the strip to the combustible heat source by means of the adhesive layer.

In some embodiments, the implementation of at least one layer of ceramic paper can be laminated with an additional layer, such as a layer of cigarette paper. The at least one ceramic paper layer may be laminated with an additional layer before the at least one ceramic paper layer is applied to the combustible heat source. A strip of laminated paper containing at least one layer of ceramic paper and an additional layer can be wrapped around a combustible heat source in the same manner as a strip of ceramic paper. In some embodiments, the implementation of the multilayer paper can be positioned so that at least one layer of ceramic paper faces a combustible heat source. In other words, at least one layer of ceramic paper can be positioned radially within the additional layer. In some embodiments, the laminated paper may be positioned such that the additional layer faces a combustible heat source.

Although the present invention relates to ceramic paper, a cellulose derivative binder can be used as a binder in other layers used to surround at least a portion of the length of the combustible heat source of the aerosol generating article. The binder based on cellulose derivatives can be used in the layer of any fibrous material. A binder based on cellulose derivatives can be used in a layer of fibrous material containing ceramic fibers.

A binder based on cellulose derivatives can be used in a fiber-reinforced airgel layer.

In the context of this document, the term "airgel" is used to describe open cell foam. The airgel may be of the mesoporous type. The term "mesoporous" refers to a material that has pores ranging in diameter from about 2 nanometers to about 50 nanometers. The airgel may contain a network of interconnected structures, and the network of interconnected structures may be nanostructures. The airgel may have a porosity of about 50 percent or more. The airgel may have a porosity of about 90 percent or more. An airgel can be created by extracting a liquid component from a conventional gel. Conventional gel will be understood as a semi-solid colloidal suspension of a solid suspension diluted in a liquid.

Aerogels generally have very low thermal conductivity. Without wishing to be limited by theory, conductive heat transfer in aerogels is slowed down due to their high porosity, while convective heat transfer in airgels is slowed down due to the small diameter of the pores. The small pore diameter limits the movement of air through the airgel.

In the context of this document, the term "fiber-reinforced airgel" refers to a composite material containing an airgel matrix reinforced with fibrous material.

The present invention will now be described solely by way of example, with reference to the accompanying drawings, in which:

in fig. 1 schematically shows a first embodiment of an aerosol generating article according to the present invention, which comprises a continuous combustible heat source;

in fig. 2 shows the temperature profiles of aerosol generating products like those shown in FIG. 1, in the first position in the products;

in fig. 3 shows the temperature profiles of aerosol generating products like those shown in FIG. 1, in the second position in the products;

in fig. 4 shows the temperature profiles of aerosol generating products like those shown in FIG. 1, in the third position in the products;

in fig. 5 shows temperature profiles of additional aerosol generating products like those shown in FIG. 1 in the third position in the articles, wherein one of the aerosol generating articles contains a ceramic paper containing biosoluble fibers based on alkaline earth metal silicate, and

in fig. 6 schematically shows a second embodiment of an aerosol generating article of the present invention comprising a non-continuous combustible heat source.

In FIG. 1 schematically shows an aerosol generating article 2. The aerosol generating article 2 contains a combustible heat source 3 . The combustible heat source 3 comprises a substantially round-cylindrical carbonaceous material body having a length of approximately 10 millimeters. The combustible heat source 3 is a continuous heat source. In other words, the combustible heat source 3 does not contain any air passages passing through it.

The aerosol generating article 2 further comprises an aerosol generating substrate 4. The aerosol forming substrate 4 is located at the proximal end of the combustible heat source 3 . The aerosol-forming substrate 4 comprises a substantially round-cylindrical rod of tobacco material 18 surrounded by a filter ficella 19.

A non-combustible, substantially airtight first baffle 6 is located between the proximal end of the combustible heat source 3 and the distal end of the aerosol generating substrate 4. The first baffle 6 contains an aluminum foil disc. The first baffle 6 also forms a heat-conducting component between the combustible heat source 3 and the aerosol-forming substrate 4 for conducting heat from the inner surface of the combustible heat source 3 to the outer surface of the aerosol-forming substrate 4.

The heat-conducting element 9 surrounds the proximal part of the combustible heat source 3 and the distal part of the aerosol-forming substrate 4. The heat-conducting element 9 contains an aluminum foil tube. The heat-conducting element 9 is in direct contact with the proximal part of the combustible heat source 3 and the ficell 19 of the filter of the aerosol-forming substrate 4.

The aerosol generating article 2 further comprises various other components located in the vicinity of the aerosol generating substrate 4, including: a transfer element 11 located at the proximal end of the aerosol generating substrate 4; an element 12, cooling aerosol, located at the proximal end of the moving element 11; a separating element 13 located at the proximal end of the aerosol cooling element 11; and a mouthpiece 10 located at the proximal end of the separating element 13.

The components of the aerosol generating article 2 are wrapped in a layer of cigarette paper 7. The layer of cigarette paper 7 surrounds the heat transfer element 9 but does not extend beyond the distal end of the heat transfer element 9 along the distal portion of the combustible heat source 3.

According to the present invention, the aerosol generating article 2 further comprises a ceramic paper layer 5. The ceramic paper layer 5 surrounds substantially the length of the combustible heat source 3 and the distal portion of the cigarette paper layer 7, the heat transfer element 9 and the aerosol generating substrate 4. In other words, the ceramic paper layer 5 is the radially outer layer at the distal end of the aerosol generating article 2.

The ceramic paper layer 5 contains from about 60 weight percent silica to about 70 weight percent silica; about 16 weight percent calcium oxide to about 22 weight percent calcium oxide; and about 12 weight percent magnesium oxide to about 19 weight percent magnesium oxide. The ceramic paper layer 5 also contains alumina. The ceramic paper layer 5 also contains a binder based on cellulose derivatives. The cellulose derivative binder contains CMC dispersed in water at a concentration of 8 weight percent.

A plurality of air inlets 8 are located on the aerosol generating substrate 4, which allows ambient air to be drawn into the aerosol generating article 2. The air inlets 8 comprise a plurality of perforations in the cigarette paper layer 7 and the lower ficell layer 19 which surrounds the aerosol forming substrate 4. The air inlets 8 are located between the outer surface and the inner surface of the aerosol-forming substrate 4.

When the user puffs on the mouthpiece 10 of the aerosol generating article 2, ambient air can be drawn into the aerosol generating article 2 through the air inlets 8. The air drawn into the aerosol generating article 2 can pass along the airflow passage of the aerosol generating article 2 from the air inlets 8 through the aerosol generating substrate 4, the moving element 11, the cooling element 12 and the separating element 13 to the mouthpiece 10 , and exits the mouthpiece 10 for inhalation by the user. The main direction of air flow through the aerosol generating article 2 is indicated by arrows.

In use, the user can ignite the combustible heat source 3 by exposing the combustible heat source 3 to an external heat source such as a lighter. The combustible heat source 3 can ignite and burn, and heat can be transferred from the combustible heat source 3 to the aerosol-forming substrate 4 by passing through the heat-conducting component 6 and the heat-conducting element 9. Volatile compounds can be vaporized from the heated aerosol-forming substrate 4. The user can puff on the mouthpiece 10 of the aerosol generating article 2 by drawing ambient air into the airflow passage of the aerosol generating article 2 through the air inlets 8 . The vapor from the heated aerosol forming substrate 4 may be entrained by air drawn through the aerosol forming substrate 4 and may be drawn with the air towards the mouthpiece 10. When the vapor is drawn towards the mouthpiece 10, the vapor may be cooled to create an aerosol. The aerosol may be drawn from the mouthpiece 10 and delivered to the user for inhalation.

It will be appreciated that the substantially airtight first baffle 6 blocks air drawn through the combustible heat source 3 into the aerosol generating substrate 4. Thus, the first baffle 6 essentially isolates the air flow path of the aerosol generating article 2 from the combustible heat source 3 .

In this embodiment, the ceramic paper layer 5 extends over a small portion of the distal end of the aerosol forming substrate 4. Thus, the ceramic paper layer 5 is at a distance from the air inlets 8. This distance substantially insulates the ceramic paper layer 5 from the air inlets 8 such that the air drawn through the airflow passage of the aerosol generating article 2 does not come into contact with the ceramic paper layer 5.

It will be appreciated that in some embodiments, the ceramic paper layer may be in close proximity to the air inlets. In these embodiments, portions of the ceramic paper layer that are in close proximity to the air inlets may be coated with materials that are substantially impervious to fibers and particles. This can substantially isolate portions of the ceramic paper layer that are in close proximity to the air inlets such that air drawn through the airflow passage of the aerosol generating article does not come into contact with the ceramic paper layer.

Experimental data were collected to determine the temperature of combustible heat sources and aerosol generating substrates of various aerosol generating articles like the aerosol generating articles 2 shown in FIG. 1 for the burning period of the combustible heat source. Each of the aerosol generating articles tested contained a different layer of material surrounding substantially the length of the combustible heat source. During the experiment, holes 2 mm deep were formed in the aerosol-generating products; wherein two of the holes were formed in the combustible heat source at the positions T ₁ and T ₂ shown in FIG. 1 and one of the holes was formed in the aerosol-forming substrate at the T ₃ position shown in FIG. 1. A thermocouple was inserted into each hole to provide a temperature measurement at each position. In particular, experimental data was collected for aerosol generating articles containing a layer of ceramic paper surrounding substantially the length of the combustible heat source and not containing a layer of material surrounding essentially the length of the combustible heat source. In FIG. Figures 2–4 show graphs of experimental temperature measurements over a certain time in three different places of different products that generate aerosol.

In FIG. 2 shows the temperature measured at a position 2 millimeters from the distal end of the combustible heat source, which corresponds to the position T ₁ shown in FIG. 1. In other words, in FIG. 2 shows the temperature at the far end of a combustible heat source.

In FIG. 3 shows the temperature measured at a position 5 millimeters from the distal end of the combustible heat source, which corresponds to the position T ₂ shown in FIG. 1. In other words, in FIG. 3 shows the temperature at a position approximately midway along the length of the combustible heat source.

In FIG. 4 shows the temperature measured at a position 11 millimeters from the distal end of the combustible heat source, which corresponds to position T ₃ in FIG. 1. In other words, in FIG. 4 shows the temperature at the far end of the aerosol forming substrate.

All temperature profiles were measured using electronic temperature sensors embedded approximately 2 millimeters deep into the relevant components of the aerosol generating articles.

In FIG. 2, 3 and 4, the "SMAR" line, numbered 20, shows the temperature profile of an aerosol generating article with an "open" combustible heat source. In other words, "SMAR" line 22 shows the temperature profile of the aerosol generating article without a layer of material surrounding substantially the length of the combustible heat source.

In FIG. 2, 3 and 4, the "ceramic paper 1" line, numbered 21, shows the temperature profile of an aerosol generating article with a layer of ceramic paper surrounding a substantially length of the combustible heat source. The ceramic paper surrounding substantially the length of the combustible heat source in the "ceramic paper 1" test was Superwool® Plus Fiber available from Morgan Advanced Materials, plc.

In FIG. 2, 3 and 4, the "ceramic paper 2" line, referenced at 22, shows the temperature profile of an aerosol generating article with a layer of ceramic paper surrounding substantially the length of the combustible heat source. The ceramic paper surrounding the substantially length of the combustible heat source in the "Ceramic Paper 2" test was CFP Ceramic Fiber Paper available from Ningbo Firewheel Thermal Insulation & Sealing Co., Ltd.

In FIG. 2, 3 and 4, the "glass paper" line at 23 shows the temperature profile of an aerosol generating article with a layer of ceramic paper surrounding substantially the length of the combustible heat source. The ceramic paper surrounding substantially the length of the combustible heat source in the "glass paper" test was glass fiber-containing ceramic paper.

It is desirable that aerosol generating articles having a layer of material surrounding substantially the length of the aerosol generating article exhibit temperature profiles substantially similar to or greater than the temperature profile 20 of an aerosol generating article with an exposed combustible heat source without a layer of material surrounding substantially the length of the aerosol generating article. combustible heat source. If the combustible heat source has a similar or higher temperature than the exposed combustible heat source, this indicates that the layer of material surrounding a substantially length of the combustible heat source does not substantially suppress combustion of the combustible heat source.

Surprisingly, as shown in FIG. 2, 3, and 4, the temperature profiles 21, 22, 23 of an aerosol generating article having a layer of ceramic paper surrounding substantially the length of the combustible heat source are substantially similar to the temperature profile 20 of the aerosol generating article, with no layer of material surrounding substantially the length. combustible heat source at all three test locations of the aerosol generating article during most of the combustion time of the combustible heat source. Moreover, the temperature profiles 21 and 22 of an aerosol generating article having a layer of ceramic paper surrounding substantially the length of the combustible heat source actually exceed the temperature profile 20 of the aerosol generating article without a layer of material surrounding substantially the length of the combustible heat source, for some periods of time during an aerosol generating session.

This surprising result indicates that providing at least one layer of ceramic paper surrounding a substantially length of the combustible heat source advantageously does not substantially prevent combustion of the combustible heat source. In fact, the provision of the ceramic paper layer may increase the temperature of the combustible heat source for periods of time while the combustible heat source is burning.

In FIG. 5 shows a plot of additional experimental data collected as described above for three specific aerosol generating products. As in FIG. 4 in FIG. 5 shows the temperature at the distal end of the aerosol forming substrate measured at a position 11 millimeters from the distal end of the combustible heat source, which corresponds to position T ₃ in FIG. 1. Temperature profiles were again measured using electronic temperature sensors embedded approximately 2 millimeters deep into the aerosol generating substrate of the aerosol generating articles.

In FIG. 5, the "SMAR" line at 30 shows the temperature profile of an aerosol generating article with an "open" combustible heat source. In other words, "SMAR" line 22 shows the temperature profile of the aerosol generating article without a layer of material surrounding substantially the length of the combustible heat source.

In FIG. 5, the "glass paper" line at 31 shows the temperature profile of an aerosol generating article with a layer of ceramic paper surrounding a substantially length of the combustible heat source. The ceramic paper surrounding substantially the length of the combustible heat source in the "glass paper" test was glass fiber-containing ceramic paper. The glass fiber-containing ceramic paper had a thickness of approximately 1 millimeter and a length of approximately 5.5 millimeters extending from the distal end of the combustible heat source along the entire length of the combustible heat source and the distal end of the aerosol forming substrate.

In FIG. 5, the "biosoluble fibers" line at 32 shows the temperature profile of an aerosol generating article with a layer of ceramic paper surrounding substantially the length of the combustible heat source. The ceramic paper surrounding substantially the length of the combustible heat source in the "biosoluble fiber" test was Superwool® Plus Fiber available from Morgan Advanced Materials, plc. Superwool® Plus Fiber contains biosoluble fibers based on alkaline earth metal silicate. Ceramic paper containing biosoluble fibers having a thickness of approximately 0.5 millimeters and a length of approximately 5.5 millimeters, extending from the distal end of the combustible heat source along the entire length of the combustible heat source and the distal end of the aerosol forming substrate.

Surprisingly, as shown in FIG. 5, it has been found that the temperature profile 32 of an aerosol generating article having a ceramic paper layer containing biosoluble alkaline earth metal silicate fibers indicates a higher temperature after a period of about 200 seconds than the temperature profile 30 of a product generating aerosol, without a layer of material surrounding substantially the length of the combustible heat source, and the temperature profile 31 of the aerosol generating article with the glass fiber-containing ceramic paper layer after a period of 200 seconds.

This surprising result indicates that smoking time can be increased by providing an aerosol generating article with a layer of ceramic paper containing alkaline earth metal silicate biosoluble fibers surrounding a substantially length of combustible heat source, even compared to articles having a layer ceramic paper containing glass fibers surrounding substantially the length of the combustible heat source.

The aerosol generating articles of the present invention were tested by observing their effect after placing them on sheets of Whatman paper after ignition of a heat source. For example, aerosol generating articles were subjected to conditions of approximately 23°C ± 3°C and 55% ± 5% relative humidity for 24 hours. The exposed aerosol generating articles were ignited using electric lighters and left to burn for a period of 2 minutes. After 2 minutes, the aerosol generating articles were placed on a stack of sheets of Whatman paper for a period of 10 minutes. After 10 minutes, the sheets of Whatman paper were examined and it was found that the aerosol-generating article having a layer of ceramic paper surrounding substantially the length of the combustible heat source did not form a hole in any sheet of Whatman paper, but left a small darkened area on the top sheet. paper. This result shows that the presence of a layer of ceramic paper surrounding a substantially length of the combustible heat source lowers the surface temperature in the vicinity of the heat source.

In FIG. 6 schematically shows a second embodiment of an aerosol generating article according to the present invention. The aerosol generating product 102 is substantially similar to the aerosol generating product 2 shown in FIG. 1. The aerosol generating article 102 comprises a combustible heat source 103, an aerosol generating substrate 104, a ceramic paper layer 105, and a cigarette paper layer 107 arranged similarly to those of the aerosol generating article 2 shown in FIG. 1. However, the combustible heat source 103 is a non-continuous combustible heat source. The discontinuous heat source 103 comprises an annular body 115 of carbonaceous material having a passage 116 extending between the far end surface and the near end surface. Passage 116 forms part of an airflow passage through the aerosol generating article and allows air to be drawn from the proximal end of the aerosol generating article through the combustible heat source 103 and into the aerosol generating substrate 104. The ceramic paper layer 105 is spaced away from the airflow passage through the aerosol generating article 102 such that air drawn through the airflow passage does not contact the ceramic paper layer 105.

A non-combustible, substantially airtight first baffle 106 is located between the proximal end of the combustible heat source 103 and the distal end of the aerosol generating substrate 104, and is similar to the first baffle 6 described above with respect to FIG. 1. However, unlike the first baffle 6 described above, the first baffle 106 includes an opening 120 aligned with the passage 116 to allow air to pass from the passage 116 into the aerosol forming substrate 104.

A non-combustible, substantially airtight second baffle 117 is provided on the inner surface of the passage 116. The second baffle 117 isolates the passage of air through the passage 116 from the combustible heat source 103 and combustion products of the combustible heat source.

Since the combustible heat source 103 is a non-continuous heat source, the aerosol generating article 102 does not include air inlets located on the aerosol generating substrate 104. When a user puffs on the mouthpiece of the aerosol generating article 102, ambient air may be drawn into the aerosol generating article 102 through the passage 116 through the heat source 103. The air drawn into the aerosol generating article 102 may pass along the airflow passage of the aerosol generating article 102 , generating aerosol, through the passage 116, through the substrate 104, forming an aerosol, moving element, cooling element and separation element to the mouthpiece, and from the mouthpiece to the user for inhalation. The main direction of air flow through the aerosol generating article 102 is indicated by arrows.

It will be appreciated that, in some embodiments, other air inlets in the aerosol generating article may also be provided in addition to the passage for air flow through the combustible heat source.

The specific embodiments described above are intended to illustrate the present invention. However, other embodiments may also be suggested without departing from the scope of the present invention as defined in the claims, and it should be understood that the specific embodiments described above are not intended to be limiting.

Claims (33)

1. An aerosol generating article, comprising: an aerosol-forming substrate; combustible heat source; at least one layer of ceramic paper surrounding at least part of the length of the combustible heat source, where at least one layer of ceramic paper contains a binder based on cellulose derivatives and where the ceramic paper contains at least one of: biosoluble fibers; fibers with low biopersistence and fibers containing at least one of silicon dioxide, calcium oxide and magnesium oxide. 2. The aerosol generating article of claim 1, wherein at least one ceramic paper layer contains 40 weight percent or less of a cellulose derivative binder. 3. An aerosol generating article according to claim 1 or 2, wherein the ceramic paper contains fibers containing alkaline earth metal silicate. 4. An aerosol generating article according to any one of the preceding claims, comprising one or more airflow passages along which air can be drawn through the aerosol generating article for inhalation by a user. 5. An aerosol generating article according to any one of the preceding claims, comprising one or more non-combustible airtight barriers between the combustible heat source and the aerosol generating substrate. 6. The aerosol generating article of claim 5, wherein the non-combustible airtight baffle between the combustible heat source and the aerosol generating substrate includes a first baffle that is adjacent to one or both of the proximal end of the combustible heat source and the distal end of the aerosol generating substrate. 7. An aerosol generating article according to any one of the preceding claims, wherein at least one layer of ceramic paper is separated from one or more air flow passages such that, in use, air drawn through the aerosol generating article along one or more passages for air flow, not in direct contact with at least one layer of ceramic paper. 8. An aerosol-generating article according to any one of the preceding claims, wherein the combustible heat source, the aerosol-generating substrate, and at least one layer of ceramic paper are arranged such that the temperature of the aerosol-generating substrate does not exceed 375° C. during combustion of the fuel. heat source. 9. An aerosol generating article according to any one of the preceding claims, wherein the ceramic paper contains at least 50 weight percent ceramic material. 10. An aerosol generating article according to any one of the preceding claims, wherein at least one layer of ceramic paper has a thickness of 0.5 to 5 mm. 11. The method of forming an aerosol generating product, according to paragraphs. 1-10, wherein the method includes: an arrangement of a combustible heat source configured to heat the aerosol generating substrate; and surrounding at least part of the length of the combustible heat source with at least one layer of ceramic paper containing a binder based on cellulose derivatives. 12. The method of forming an aerosol generating article according to claim 11, wherein surrounding at least a portion of the length of a combustible heat source with at least one layer of ceramic paper comprises: providing a strip of ceramic paper containing a binder based on cellulose derivatives, having opposite ends; wrapping the strip around the combustible heat source such that the combustible heat source is surrounded by at least one layer of ceramic paper; overlapping opposite ends of the strip; and joining the overlapped ends to attach at least one layer of ceramic paper to a combustible heat source. 13. The method of forming an aerosol generating article according to claim 11, wherein surrounding at least a portion of the length of a combustible heat source with at least one layer of ceramic paper comprises: providing a strip of ceramic paper containing a binder based on cellulose derivatives, having opposite ends; applying a layer of adhesive to one side of the strip at least at each of the opposite ends; the location of the strip with the adhesive layer facing the combustible heat source; wrapping the strip around the combustible heat source such that the combustible heat source is surrounded by at least one layer of ceramic paper; joining opposite ends of the strip without overlapping opposite ends and attaching the strip to a combustible heat source by means of an adhesive layer.

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