RU2779532C1 - Aerosol-generating article containing a heat-conducting element, and surface treatment - Google Patents

Abstract

FIELD: smoking devices.

SUBSTANCE: group of inventions relates to the tobacco industry, namely to an aerosol-generating article and to a method for manufacturing an aerosol-generating article. Aerosol-generating article comprises a heat source, an aerosol-forming substrate in heat contact with the heat source, and a heat-conducting component placed around at least part of the aerosol-forming substrate. The heat-conducting component comprises an outer surface constituting at least part of the outer surface of the aerosol-generating article. At least part of the outer surface of the heat-conducting component comprises a surface treatment and exhibits an emittance coefficient of less than 0.6.

EFFECT: improved control of heating of the substrate due to the temperature being maintained within the desired range.

25 cl, 11 dwg

Description

The present invention relates to an aerosol-generating article that comprises a heat source, an aerosol-generating substrate in thermal contact with the heat source, and a thermally conductive component provided around at least a portion of the aerosol-generating substrate and comprising a surface coating. In some examples, the thermally conductive component comprises two or more thermally conductive elements.

A number of smoking articles have been proposed in the prior art in which tobacco is heated rather than burned. One of the objectives of such "heated" smoking articles is to reduce the content of harmful smoke constituents, which are formed as a result of combustion and pyrolytic degradation of tobacco in conventional cigarettes. In one known type of heated smoking article, the aerosol is generated by transferring heat from a combustible heat source to an aerosol-forming substrate downstream of the combustible heat source. During smoking, volatile compounds are released from the aerosol-forming substrate by heat transfer from the combustible heat source and are entrained in the airflow drawn through the smoking article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user. Typically, air is drawn into these prior art heated smoking articles through one or more airflow paths passing through the combustible heat source, and heat transfer from the combustible heat source to the aerosol generating substrate occurs by convection and conduction.

For example, WO-A-2009/022232 discloses a smoking article comprising a combustible heat source, an aerosol forming substrate downstream of the combustible heat source, and a thermal conductive member surrounding and in contact with the rear of the combustible heat source and adjacent the front part of the substrate that forms the aerosol.

The heat transfer element in the smoking article according to WO-A-2009/022232 conducts the heat generated by the combustion of the heat source into the aerosol-forming substrate by conduction. The removal of heat by heat transfer by conduction substantially lowers the temperature of the rear of the combustible heat source so that the temperature of the rear of the combustible heat source is maintained substantially below its autoignition temperature.

In aerosol-generating articles in which the aerosol-generating substrate is heated, such as smoking articles in which tobacco is heated, the temperature obtained in the aerosol-generating substrate significantly affects the aerosol-generating ability perceived by the senses. It is generally desirable to maintain the temperature of the aerosol generating substrate within a certain range in order to optimize the delivery of the aerosol to the user. In some cases, radiative heat loss from the outer surface of the heat transfer element can cause the temperature of the combustible heat source or aerosol generating substrate to drop outside the desired range, thereby affecting the performance of the smoking article. If the temperature of the aerosol generating substrate falls too low, for example, the consistency and amount of aerosol delivered to the user can be adversely affected.

Certain heated aerosol generating articles involve convective heat transfer from the combustible heat source to the aerosol generating substrate in addition to heat transfer by conduction. For example, in some prior art smoking articles, at least one longitudinal airflow passage extends through a combustible heat source to provide convective heating to the aerosol generating substrate. In such smoking articles, the aerosol-forming substrate is heated by a combination of conduction heating and convective heating.

In other heated smoking articles, it may be preferable to provide a combustible heat source without airflow passages through the heat source. In such smoking articles, there may be limited convective heating of the aerosol-forming substrate, and heating of the aerosol-forming substrate is achieved primarily by conduction heat transfer from the heat transfer element. When the aerosol-forming substrate is heated primarily by conduction heat transfer, the temperature of the aerosol-forming substrate may become more sensitive to changes in the temperature of the thermally conductive element. This means that any cooling of the heat transfer element due to heat loss to radiation may have a greater effect on aerosol formation than in smoking articles where convective heating of the aerosol generating substrate is also available.

It would be desirable to provide a heated smoking article comprising a heat source and an aerosol generating substrate located downstream of the heat source, which provides improved smoking quality. In particular, it would be desirable to provide a heated smoking article having improved heat control by conduction of the aerosol generating substrate in order to assist in maintaining the temperature of the aerosol generating substrate within a desired temperature range during smoking.

It would also be desirable to provide a novel means of achieving the desired appearance of such smoking articles that does not impair the internal temperature profile of the smoking article during use. For example, it may be desirable to provide a novel means by which a consumer can distinguish from one another such smoking articles containing different flavors provided in the aerosol forming substrate and delivered to the consumer during smoking.

According to an aspect of the invention, an article is provided that generates an aerosol containing a combustible heat source. The product additionally contains an aerosol-forming substrate in thermal contact with a combustible heat source. The thermally conductive component is placed around at least a portion of the aerosol generating substrate, wherein the thermally conductive component comprises an outer surface constituting at least a portion of the outer surface of the aerosol generating article. At least a portion of the outer surface of the thermally conductive component contains a surface coating and has an emissivity of less than about 0.6.

In some examples, it is preferred that the outer surface emissivity of the thermally conductive component be less than about 0.5. In some examples, the emissivity may be less than about 0.4, less than about 0.3, less than about 0.2, or less than about 0.15. Preferably, the emissivity is greater than about 0.1, greater than about 0.2, or greater than about 0.3.

Emissivity, which is a measure of the efficiency of a surface in terms of emitting energy in the form of radiant heat, is measured in accordance with ISO 18434-1, as detailed in this document in the section Method for Determining Emissivity.

In this context, the term "aerosol-forming substrate" is used to describe a substrate capable of releasing volatile compounds when heated, which can form an aerosol. The aerosol generated by aerosol-forming substrates may be visible or invisible and may contain vapors (for example, fine particles of substances that are in a gaseous state and are usually liquid or solid at room temperature), as well as gases and liquid droplets of condensed vapors.

It has been found that by providing a surface coating on at least a portion of the thermally conductive component, it is possible in some instances to control the thermal properties of the aerosol generating article. In particular, in examples of the invention, the thermally conductive component can influence the transfer of heat from a combustible heat source. The transfer of heat from an article through a thermally conductive component and the management of heat in the article can be affected by the presence of a surface coating.

The surface coating preferably contains a filler or pigment material. The filler material may contain organic or inorganic material. Preferably, the surface coating contains an inorganic filler material. Preferably, the filler material is heat resistant up to at least about 300 degrees Celsius, or at least about 400 degrees Celsius. The filler material preferably contains a pigment. Examples of the filler material include graphite, metal carbonate and metal oxide. For example, the filler material may contain one or more metal oxides selected from titanium oxide, alumina, and iron oxide. The filler may contain calcium carbonate.

The thermally conductive component may extend around and be in contact with a downstream portion of the heat source. The thermally conductive component may comprise a first thermally conductive element placed around and in contact with the downstream portion of the heat source and adjacent to the upstream portion of the aerosol-forming substrate, and a second thermally conductive element placed around at least a portion of the first thermally conductive element and containing an outer surface constituting at least a portion of the outer surface of the aerosol generating article. At least part of the outer surface of the second heat-conducting element contains a surface coating and has an emissivity less than 0.6.

The second heat-conducting element may be radially separated from the first heat-conducting element by at least one layer of heat-insulating material that extends around at least a portion of the first heat-conducting element between the first and second heat-conducting elements.

At least a portion of the outer surface of the thermally conductive component may comprise a surface treatment, where the surface treatment preferably comprises at least one of the following: embossing, blind embossing, and combinations thereof.

In embodiments of the invention, the aerosol-forming substrate is located downstream of the heat source.

In accordance with a further aspect of the present invention, an aerosol generating article is provided, comprising a heat source and an aerosol generating substrate. The aerosol generating substrate may be downstream of the heat source. The aerosol generating article further comprises a thermally conductive component around and in contact with the downstream portion of the heat source and adjacent the upstream portion of the aerosol generating substrate. The heat-conducting component contains an outer surface constituting at least a part of the outer surface of an aerosol-generating article. At least a portion of the outer surface of the thermally conductive component contains a surface treatment, such as a surface coating, and has an emissivity of less than about 0.6.

In some examples, it is preferred that the outer surface emissivity of the thermally conductive component be less than about 0.5. In some examples, the emissivity may be less than about 0.4, less than about 0.3, less than about 0.2, or less than about 0.15. Preferably, the emissivity is greater than about 0.1, greater than about 0.2, or greater than about 0.3.

The thermally conductive component may comprise a first thermally conductive element placed around and in contact with the downstream portion of the heat source and adjacent to the upstream portion of the aerosol-forming substrate, and a second thermally conductive element placed around at least a portion of the first thermally conductive element and containing an outer surface constituting at least a portion of the outer surface of the smoking article. At least a portion of the outer surface of the second heat transfer element contains a surface treatment and has an emissivity of less than about 0.6. The second heat transfer element is preferably radially separated from the first heat transfer element by at least one layer of heat insulating material that extends around at least a portion of the first heat transfer element between the first and second heat transfer elements. That is, in some instances, the second heat transfer element may not be in direct contact with the heat source or aerosol generating substrate.

In the context of this document, the terms "upstream" and "downstream" are used to describe the relative positions of elements or parts of elements of an aerosol generating article relative to the direction in which a consumer puffs from an aerosol generating article during use. The aerosol generating articles described herein comprise a downstream end (ie, an end to the mouth) and an opposite upstream end. In use, the consumer puffs on the downstream end of the aerosol generating article. The downstream end is located downstream of the upstream end, which may also be described as the distal end.

In the context of this document, the term "direct contact" is used to refer to the contact between two components without any intermediate connecting material, so that the surfaces of the components are in contact with each other.

In the context of this document, the term "radially separated" is used to mean that at least part of the second thermal element is removed from the underlying first thermal element in the radial direction in such a way that there is no direct contact between this part of the second thermal element and the first thermal element. .

An aerosol generating article according to aspects of the present invention may include a second heat transfer element that covers at least a portion of the first heat transfer element. Preferably there is a radial spacing between the first and second heat transfer elements at one or more positions on the aerosol generating article.

Preferably all or substantially all of the second heat transfer element is radially separated from the first heat transfer element by at least one layer of heat insulating material such that there is substantially no direct contact between the first and second heat transfer elements to limit or eliminate heat transfer by conduction from the first heat transfer element. to the second heat-conducting element. As a result, the second heat transfer element can maintain a lower temperature than the first heat transfer element. Radiative heat loss from the outer surfaces of the aerosol generating article can be reduced compared to an aerosol generating article that does not include a second heat transfer element around at least a portion of the first heat transfer element.

The second heat transfer element can advantageously reduce heat loss from the first heat transfer element. The second heat transfer element may be formed from a heat transfer material, the temperature of which will rise when the aerosol generating article is smoked as heat is generated by the heat source. The increased temperature of the second heat transfer element can reduce the temperature difference between the first heat transfer element and the overlying material so that heat loss from the first heat transfer element can be controlled, for example, reduced.

By adjusting the heat loss from the first heat transfer element, the second heat transfer element can advantageously help to better maintain the temperature of the first heat transfer element within a desired temperature range. The second heat transfer element can advantageously facilitate more efficient use of heat from the heat source to heat the aerosol-forming substrate to a desired temperature range. As an additional advantage, the second thermally conductive element may help to maintain the temperature of the aerosol generating substrate at a higher level. In turn, the second heat transfer element can improve the generation of an aerosol from an aerosol-forming substrate. Advantageously, the second heat transfer element can increase the overall delivery of the aerosol to the user. In particular, in embodiments where the aerosol forming substrate contains a source of nicotine, it can be seen that nicotine delivery can be significantly improved by adding a second heat transfer element.

Additionally, it has been found that the second heat transfer element advantageously increases the duration of smoking of the aerosol generating article so that more puffs can be achieved.

By providing a surface treatment to at least a portion of the thermally conductive component, such as at least a portion of the second thermally conductive element, further temperature control of the aerosol generating article is possible.

The present inventors have also determined that it is possible to provide a surface treatment on the outer surface of a thermally conductive component, such as a second thermally conductive element, to provide the desired appearance of an aerosol generating article, provided that the surface treatment maintains or maintains an emissivity of less than about 0.6 . In particular, maintaining or providing an emissivity of less than about 0.6 on those portions of the thermally conductive component or second thermally conductive element on which surface treatment is provided allows for the control of radiative heat loss from the aerosol generating article by the thermally conductive component or second thermally conductive element.

A surface coating or other surface treatment may be provided on one or more portions of the outer surface of the thermally conductive component or the second thermally conductive element. A surface coating or other surface treatment may be provided on substantially the entire outer surface of the thermally conductive component or second thermally conductive element.

The surface treatment may comprise at least one of the following: embossing, blind embossing, and combinations thereof.

In both aspects of the invention, suitable surface coatings include coatings containing at least one pigment that changes the perceived color of the substrate forming the thermally conductive component or the second thermally conductive element. For example, the coating may contain colored inks.

Additionally or alternatively, the surface coating may comprise a translucent material. The term "translucent" as used herein means a material that transmits at least about 20 percent of the light incident on the material of at least one wavelength of visible light, more preferably at least about 50 percent, most preferably at least about 80 percent. That is, for at least one wavelength of visible light, at least about 20 percent of the light incident on the translucent material is neither reflected nor absorbed by the material, preferably at least about 50 percent, most preferably at least about 80 percent. The term "visible light" is used to refer to the visible part of the electromagnetic radiation spectrum with a wavelength of about 390 to about 750 nanometers.

Translucency is measured using the ISO 2471 method. An opacity of less than about 80 percent indicates that the material is translucent. That is, for a material with an opacity of less than about 80 percent, at least about 20 percent of the light incident on the material is neither reflected nor absorbed by the material. Therefore, translucent materials have an opacity of less than about 80 percent, preferably less than about 50 percent, most preferably less than about 20 percent.

A translucent material can transmit light uniformly across the entire visible spectrum, so that the translucent material appears colorless. Alternatively, the translucent material may absorb at least 80 percent of incident light of one or more wavelengths such that the translucent material appears tinted or colored.

In any of those embodiments where the surface coating comprises a translucent material, the translucent material may be a transparent material. Transparency is a particular type of translucency, and the term "transparent" is used herein to refer to a translucent material that transmits light incident on the material without substantially scattering. That is, light falling on a transparent material passes through the material in accordance with Snell's law. Transparent materials are a kind of translucent materials.

In addition to, or alternatively to, any of the surface coatings described herein, the surface coating may comprise at least one metallic material to impart a metallic appearance to the outer surface of the thermally conductive component or second thermally conductive element. For example, the surface coating may contain metal particles, metal plates, or both. The metallic material may contain from about 10 percent to 100 percent metal by weight, preferably from about 20 percent to about 50 percent metal by weight. In some embodiments, the implementation of the metallic material may be applied in the form of a metallic paint.

In any of the embodiments described herein where the surface treatment comprises a surface coating, the surface coating may consist of a single layer. For example, the surface coating may consist of a colored or tinted transparent material. Alternatively, the surface coating may comprise several layers. In these embodiments, several layers may be the same or different. Preferably several layers are different layers. For example, the surface coating may comprise a base layer containing at least one of a pigment and a metallic material, and a transparent top layer overlying the base layer, all as described herein.

In any of the embodiments described herein where the surface treatment comprises a surface coating, the outer surface of the surface coating preferably has a smooth surface which gives a good glossy effect. For example, in some embodiments, the roughness of the surface coating, measured with a Parker-Print-Surface roughness meter according to ISO 8791-4, is from about 0.1 micrometer to about 1 micrometer, preferably less than about 0.6 micrometer.

The surface coating may be a substantially continuous coating on a portion of the thermally conductive component. In some examples, the surface coating is a discontinuous coating. For example, a coverage may include several distinct coverage areas, such as a plurality of coverage points. The percentage of area occupied by the coating may differ from one area of the covered portion to another area of the covered portion. The coating may contain different coating materials in different areas of the thermally conductive component. One or more areas of coverage may have a textured surface. Thus, additional heat management in the aerosol generating article becomes possible.

In any of the embodiments described herein where the surface treatment comprises a surface coating, the particular surface coating is selected to provide an emissivity on the outer surface of the thermally conductive component or second thermally conductive element of less than about 0.6. The inventors of the present invention have determined that some coating materials may not be suitable to provide an emissivity value within this range. For example, some surface coatings containing a significant amount of black pigment may have an emissivity of substantially greater than 0.6 and therefore give an unacceptable level of heat loss to radiation from a smoking article when applied to the outer surface of a thermally conductive component or second thermally conductive element. Therefore, coating materials and combinations of coating materials that give an emissivity greater than 0.6 are not within the scope of at least some aspects of the present invention. The skilled artisan can select suitable coating materials to provide an emissivity of less than about 0.6.

According to a further aspect of the invention, there is provided a method for manufacturing an aerosol generating article comprising a combustible heat source, an aerosol generating substrate in thermal contact with a combustible heat source, and a thermally conductive component around at least a portion of the aerosol generating substrate, wherein the thermally conductive component comprises an outer surface , constituting at least part of the outer surface of the product that generates the aerosol. The method includes the step of applying the coating composition to at least a portion of the outer surface of the thermally conductive component such that the coated portion of the thermally conductive component has an emissivity of less than about 0.6.

The coating composition may contain a filler material, a binder and a solvent. The filler material may contain one or more materials selected from graphite, metal oxides and metal carbonates. For example, the filler material may contain one or more metal oxides selected from titanium oxide, alumina, and iron oxide. The filler may contain calcium carbonate.

The binder may, for example, contain nitrocellulose, ethylcellulose or a cellulose binder, for example carboxymethylcellulose or hydroxyethylcellulose.

The solvent may, for example, contain water or another solvent, such as isopropanol.

An appropriate method can be used to coat the thermally conductive component before or after the assembly of the thermally conductive component into an aerosol generating article. For example, a printing method may be used for coating. Intaglio printing can be used for coating.

The amount of coating applied may be, for example, from about 0.5 to 2 g/m ² . The amount and thickness of the applied coating will be chosen, for example, so as to achieve the desired emissivity.

In any of the embodiments described herein, the thermally conductive component or each thermally conductive element may be made of a metal foil, such as, for example, aluminum foil, steel foil, iron foil, copper foil, or metal alloy foil. Preferably, the thermally conductive component or each thermally conductive element is made of aluminum foil. The thermally conductive component or each thermally conductive element may consist of a single layer of thermally conductive material. Alternatively, the thermally conductive component or each thermally conductive element may comprise multiple layers of thermally conductive materials. In these embodiments, multiple layers may contain the same thermal materials or different thermal materials.

Preferably, the thermally conductive component or each thermally conductive element is made from a material having a bulk thermal conductivity of from about 10 watts per meter Kelvin to about 500 watts per meter Kelvin, more preferably from about 15 watts per meter Kelvin to about 400 watts per meter Kelvin , at 23 degrees Celsius and 50 percent relative humidity, as measured by the modified transient flat source (MTPS) method.

Preferably, the thickness of the thermally conductive component or each thermally conductive element is from about 5 micrometers to about 50 micrometers, more preferably from about 10 micrometers to about 30 micrometers, and most preferably about 20 micrometers.

In those embodiments where the thermally conductive component or second thermally conductive element is made of metal foil and the surface treatment comprises a surface coating, the surface coating may comprise a metal oxide layer. The metal oxide layer may be in addition to or alternative to any of the surface coating materials described herein.

As described herein, the present inventors have determined that maintaining or providing an emissivity of less than about 0.6 when applying a surface treatment to the outer surface of a thermally conductive component or second thermally conductive element optimizes the thermal performance of an aerosol generating article by controlling heat loss. to radiation through the heat-conducting component or the second heat-conducting element. The present inventors have also determined that the effect of reducing radiant heat loss can be particularly significant when the emissivity of the outer surface of the thermal conductive component or the second thermal conductive element is less than about 0.5. Therefore, in any of the embodiments described herein, portions of the outer surface of the thermally conductive component or second thermally conductive element containing the surface treatment may have an emissivity of less than about 0.5, or less than about 0.4.

In accordance with a further aspect of the present invention, an aerosol generating article is provided, comprising a heat source and an aerosol generating substrate downstream of the heat source. The aerosol-generating article further comprises a first heat-conducting element placed around and in contact with the downstream part of the heat source and adjacent to the upstream part of the aerosol-generating substrate, and the second heat-conducting element placed around at least a part of the first heat-conducting element. element and containing the outer surface constituting at least part of the outer surface of the product that generates the aerosol. The second heat-conducting element is separated in the radial direction from the first heat-conducting element by at least one layer of heat-insulating material, which passes around at least a part of the first heat-conducting element between the first and second heat-conducting elements. The outer surface of the second thermal element may have an emissivity of less than about 0.6, and in some examples less than 0.5

The second heat transfer element may be made of a metal foil, such as, for example, aluminum foil, steel foil, iron foil, copper foil or metal alloy foil. Preferably, the second heat transfer element is made of aluminum foil. The second thermally conductive element may consist of a single layer of thermally conductive material. Alternatively, the second thermally conductive element may comprise multiple layers of thermally conductive materials. In these embodiments, multiple layers may contain the same thermal materials or different thermal materials.

Preferably, the second thermal element is made of a material having a volumetric thermal conductivity of from about 10 watts per meter Kelvin to about 500 watts per meter Kelvin, more preferably from about 15 watts per meter Kelvin to about 400 watts per meter Kelvin, at a temperature 23 degrees Celsius and 50 percent relative humidity, as measured by the modified transient flat source (MTPS) method.

Preferably, the thickness of the second thermally conductive element is from about 5 micrometers to about 50 micrometers, more preferably from about 10 micrometers to about 30 micrometers, and most preferably about 20 micrometers.

According to aspects of the invention and in any of the embodiments described herein, at least one layer of thermal insulation material may comprise one or more layers of paper. The paper preferably provides complete separation of the first and second heat transfer elements so that there is no direct contact between the surfaces of the heat transfer elements.

Particularly preferably, the first and second heat transfer elements are separated by a paper wrapper that extends along the entire length of the aerosol generating article. In such embodiments, a paper wrapper is wrapped around the first thermal element and then a second thermal element is placed over at least a portion of the paper wrapper.

The provision of a second heat transfer element over the paper wrapper provides additional benefits regarding the appearance of the aerosol generating articles according to aspects of the invention, and in particular regarding the appearance of the aerosol generating article during and after smoking. In certain cases, some discoloration of the paper wrapper in the area of the heat source is observed when the wrapper is exposed to heat from the heat source. In addition, the paper wrapper may become stained as a result of the transfer of the aerosol generating agent from the aerosol generating substrate into the paper wrapper. In aerosol generating articles according to aspects of the invention, a second heat transfer element may be provided over at least a portion of the heat source and an adjacent portion of the aerosol generating substrate such that discoloration or stains on the wrapper are covered and no longer visible. Therefore, the initial appearance of the aerosol generating article can be maintained during smoking.

Alternatively, or in addition to the intermediate layer of paper between the first and second heat transfer elements, at least a portion of the first and second heat transfer elements may be radially separated by an air gap such that at least one heat insulating material layer contains an air gap. An air gap can be provided by adding one or more spacer elements between the first heat transfer element and the second heat transfer element to maintain a certain spacing between them. This can be achieved, for example, by perforating, embossing or blind embossing of the second heat-conducting element. In such embodiments, the embossed or blind embossed parts of the second heat transfer element may be in contact with the first heat transfer element, and the non-embossed parts are separated from the first heat transfer element by an air gap, or vice versa. Alternatively, one or more separate separating elements may be provided between the heat-conducting elements.

Preferably, the first and second heat transfer elements are radially spaced from each other by at least 50 micrometers, more preferably at least 75 micrometers, and most preferably at least 100 micrometers. Where one or more paper layers are provided between the thermal elements as described herein, the radial spacing of the thermal elements will be determined by the thickness of the one or more paper layers.

As described herein, the thermally conductive component or first thermally conductive element of the aerosol generating articles according to aspects of the invention may be in contact with the downstream portion of the heat source and adjacent the upstream portion of the aerosol generating substrate. In embodiments with a combustible heat source, the thermally conductive component or first thermally conductive element is preferably resistant to combustion and limits the supply of oxygen.

In particularly preferred embodiments, the thermally conductive component or first thermally conductive element forms a continuous sleeve tightly surrounding the downstream portion of the heat source and the upstream portion of the aerosol generating substrate.

Preferably, the thermally conductive component or first thermally conductive element provides a substantially sealed connection between the heat source and the aerosol generating substrate. This advantageously prevents the combustion gases from the heat source from being easily drawn into the aerosol-forming substrate through its periphery. Such a connection also minimizes or substantially prevents convective heat transfer from the heat source to the aerosol-forming substrate via hot air drawn in along the periphery.

The thermally conductive component or first thermally conductive element may be made from any suitable heat resistant material or combination of materials with appropriate thermal conductivity. Preferably, the thermally conductive component or first thermally conductive element is made of a material having a bulk thermal conductivity of from about 10 watts per meter Kelvin to about 500 watts per meter Kelvin, more preferably from about 15 watts per meter Kelvin to about 400 watts per meter Kelvin , at 23 degrees Celsius and 50 percent relative humidity, as measured by the modified transient flat source (MTPS) method.

Suitable heat transfer components or first heat transfer elements for use in smoking articles according to aspects of the present invention include, but are not limited to, metal foil such as, for example, aluminum foil, steel foil, iron foil, and copper foil; and metal alloy foil. The thermally conductive component or the first thermally conductive element may consist of a single layer of thermally conductive material. Alternatively, the thermally conductive component or first thermally conductive element may comprise multiple layers of thermally conductive materials. In these embodiments, multiple layers may contain the same thermal materials or different thermal materials.

The first heat-conducting element may be made from the same material as the second heat-conducting element, or from a different material. Preferably, the first and second heat transfer elements are made of the same material, most preferably aluminum foil.

Preferably, the thickness of the first thermally conductive element is from about 5 micrometers to about 50 micrometers, more preferably from about 10 micrometers to about 30 micrometers, and most preferably about 20 micrometers. The thickness of the first heat transfer element may be substantially equal to the thickness of the second heat transfer element, or the heat transfer elements may have different thicknesses relative to each other. Preferably, both the first and second heat transfer elements are made of aluminum foil about 20 micrometers thick.

Preferably, the downstream portion of the heat source surrounded by the heat transfer component or first heat transfer element has a length of about 2 millimeters to about 8 millimeters, more preferably a length of about 3 millimeters to about 5 millimeters.

Preferably, the upstream portion of the heat source not surrounded by the heat transfer component or the first heat transfer element has a length of from about 5 millimeters to about 15 millimeters, more preferably a length of from about 6 millimeters to about 8 millimeters.

Preferably, the aerosol-forming substrate extends downstream of the thermally conductive component or first thermally conductive element by at least about 3 millimeters. In other embodiments, the aerosol generating substrate may extend downstream of the thermally conductive component or first thermally conductive element by less than 3 millimeters. In other embodiments, the entire length of the aerosol forming substrate may be surrounded by a thermally conductive component or a first thermally conductive element.

In certain preferred embodiments, the implementation of the second heat-conducting element may be made in the form of a separate element. Alternatively, the second thermally conductive element may form part of a multilayer or layered material containing the second thermally conductive element in combination with one or more thermally insulating layers. The layer forming the second heat-conducting element may be made from any of the materials mentioned here. In certain embodiments, the second thermally conductive element may be in the form of a laminate comprising at least one thermally insulating layer laminated to the second thermally conductive element, where the thermally insulating layer forms an inner layer of the laminate adjacent to the first thermally conductive element. Thus, the heat-insulating layer of the layered structure provides the desired separation in the radial direction of the first heat-conducting element and the second heat-conducting element.

The use of a laminate for the second thermally conductive element may be of additional benefit in the manufacture of the aerosol generating articles of the invention, since the thermally insulating layer may provide additional strength and rigidity. This allows the material to be processed more easily, with less risk of crushing or tearing the second thermal element, which can be relatively thin and brittle.

One example of a particularly suitable laminate for the second thermal element is a two-layer laminate that includes an outer layer of aluminum and an inner layer of paper.

The location and extent of the second heat transfer element with respect to the first heat transfer element and the underlying heat source, as well as the aerosol generating substrate, can be controlled in order to control the heating of the smoking article during smoking. The second thermally conductive element may be positioned on top of at least a portion of the aerosol generating substrate. Alternatively or in addition, the second heat transfer element may be located on top of at least part of the heat source. More preferably, the second heat transfer element is provided on top of both the aerosol forming substrate part and the heat source part, similar to the first heat transfer element.

The extent of the second heat transfer element relative to the first heat transfer element in the upstream and downstream directions can be adjusted depending on the desired performance of the aerosol generating article.

The second heat transfer element may cover substantially the same area of the aerosol generating article as the first heat transfer element such that the heat transfer elements extend the same length of the aerosol generating article. In such a case, the second heat transfer element preferably lies directly on top of the first heat transfer element and completely covers the first heat transfer element.

Alternatively, the second heat transfer element may extend beyond the first heat transfer element in an upstream direction, a downstream direction, or both upstream and downstream directions. Alternatively or in addition, the first heat transfer element may extend beyond the second heat transfer element in at least one of the upstream and downstream directions.

Preferably, the second heat transfer element does not extend beyond the first heat transfer element in the upstream direction. The second heat transfer element may extend to approximately the same position on the heat source as the first heat transfer element, thus the first and second heat transfer elements are substantially aligned on top of the heat source. Alternatively, the first heat transfer element may extend beyond the second heat transfer element in an upstream direction. This placement can reduce the temperature of the heat source.

Preferably, the second heat transfer element extends to at least the same position as the first heat transfer element in the downstream direction. The second thermal conductive element may extend to approximately the same position on the aerosol generating substrate as the first thermal conductive element, thus the first and second thermal conductive elements are substantially aligned on top of the aerosol generating substrate. Alternatively, the second thermal element may extend beyond the first thermal element in a downstream direction such that the second thermal element covers a greater portion of the length of the aerosol forming substrate than the first thermal element. For example, the second thermal element may extend at least 1 millimeter beyond the first thermal element, or at least 2 millimeters beyond the first thermal element. However, the aerosol generating substrate preferably extends at least 2 millimeters beyond the first thermal conductive element in a downstream direction such that the downstream portion of the aerosol generating substrate remains uncovered by both thermal conductive elements.

In aerosol generating articles according to all aspects of the invention, heat is generated by a heat source. The heat source may be, for example, a radiator, a chemical heat source, a combustible heat source, or an electrical heat source. The heat source is preferably a combustible heat source and contains any suitable combustible material including, but not limited to, coal, aluminum, magnesium, carbides, nitrites, and mixtures thereof.

Preferably, the heat source of the aerosol generating articles of the invention is a carbonaceous combustible heat source.

In the context of this document, the term "carbonaceous" is used to describe a heat source containing carbon. Preferably, the carbonaceous combustible heat sources of the 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 by dry weight of the combustible heat source.

In some embodiments, the heat source of the aerosol generating articles of the invention is 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 smoking articles of the 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 80 percent by weight. dry weight of the carbon-based combustible heat source.

The aerosol generating articles of the invention may comprise combustible carbonaceous heat sources formed from one or more suitable carbonaceous materials.

If necessary, one or more binders can be combined with one or more carbonaceous materials. Preferably, one or more of the binders are organic binders. Suitable known organic binders include, but are not limited to, gums (eg, guar gum), modified celluloses and cellulose derivatives (eg, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose), flours, starches, sugars, vegetable oils, and combinations thereof.

In one preferred embodiment, the combustible heat source is made from a mixture of coal powder, modified cellulose, flour and sugar.

Instead of or in addition to one or more binders, the combustible heat sources for use in smoking articles of the present invention may contain one or more additives to improve the properties of the combustible heat source. Suitable additives include, but are not limited to, additives to improve solidification of the combustible heat source (e.g., sintering aids), additives to improve ignition of the combustible heat source (e.g., oxidizing agents such as perchlorates, chlorates, nitrates, peroxides, permanganates, and/or zirconium) , additives for improving the combustion of a combustible heat source (for example, potassium and potassium salts such as potassium citrate) and additives for improving the decomposition of one or more gases formed as a result of the combustion of a combustible heat source (for example, catalysts such as CuO, Fe ₂ O ₃ and Al ₂ O ₃ ).

The combustible carbonaceous heat sources for use in aerosol generating articles of the invention are preferably formed by mixing one or more carbonaceous materials with one or more binders and other additives, if included, and preforming the mixture into a desired shape. The mixture of one or more carbonaceous materials, one or more binders, and optional other additives may be preformed into the desired shape using any suitable known ceramic shaping techniques such as, for example, slip casting, extrusion, injection molding, and stamping. In some preferred embodiments, the mixture is preformed into the desired shape by extrusion.

Preferably, the mixture of one or more carbonaceous materials, one or more binders and other additives is preformed into an elongated rod. However, it should be understood that the mixture of one or more carbonaceous materials, one or more binders, and other additives may be preformed into other desired shapes.

After molding, in particular after extrusion, the elongate rod or other desired shape is preferably dried to reduce moisture content and then subjected to pyrolysis in a non-oxidizing atmosphere at a temperature sufficient to carburize one or more binders, if any, and substantially remove any volatiles in an elongated rod or other form. The elongate rod or other desired shape is preferably pyrolyzed under a nitrogen atmosphere at a temperature of from about 700 degrees Celsius to about 900 degrees Celsius.

The combustible heat source preferably has a porosity of from about 20 percent to about 80 percent, more preferably from about 20 percent to 60 percent. Even more preferably, the combustible heat source has a porosity of from about 50 percent to about 70 percent, more preferably from about 50 percent to about 60 percent, as measured by, for example, mercury porosimetry or helium pycnometry. The required porosity can be easily achieved during the manufacture of the combustible heat source using conventional methods and technology.

Advantageously, combustible carbonaceous heat sources for use in aerosol generating articles of the invention have an apparent density of from about 0.6 grams per cubic centimeter to about 1 gram per cubic centimeter.

Preferably, the combustible heat source has a mass of from about 300 milligrams to about 500 milligrams, more preferably from about 400 milligrams to 450 milligrams.

Preferably, the combustible heat source has a length of from about 7 millimeters to about 17 millimeters, more preferably from about 7 millimeters to about 15 millimeters, most preferably from about 7 millimeters to about 13 millimeters.

Preferably, the combustible heat source has a diameter of from about 5 millimeters to about 9 millimeters, more preferably from about 7 millimeters to about 8 millimeters.

Preferably, the combustible heat source has a substantially constant diameter. However, the combustible heat source may alternatively be conical, so that the diameter of the rear of the combustible heat source is greater than the diameter of its front. Particularly preferred are combustible heat sources which are substantially cylindrical. The combustible heat source may, for example, be a cylinder or conical cylinder with a substantially circular cross section, or a cylinder or conical cylinder with a substantially elliptical cross section.

The aerosol generating articles of the invention will comprise one or more airflow paths along which air can be drawn through the aerosol generating article for inhalation by the user.

In some embodiments of the invention, the heat source may include at least one longitudinal air flow channel providing one or more air flow paths through the heat source. In the context of this document, the term "airflow duct" is used to describe a duct running along the length of the heat source through which air can be drawn through the aerosol generating article for inhalation by the user. Such heat sources containing one or more longitudinal airflow channels are referred to herein as "discontinuous" heat sources.

The diameter of the at least one longitudinal airflow passage may be from about 1.5 millimeters to about 3 millimeters, more preferably from about 2 millimeters to about 2.5 millimeters. The inner surface of at least one longitudinal air flow channel may be partially or completely covered, as described in more detail in document WO-A-2009/022232.

In alternative embodiments, there are no longitudinal airflow channels in the heat source so that air drawn through the aerosol generating article does not pass through any airflow channels along the heat source. Such heat sources are referred to herein as "solid" heat sources. Aerosol generating articles containing continuous heat sources define alternative airflow paths through the smoking article.

In the aerosol generating articles of the invention comprising continuous heat sources, heat transfer from the heat source to the aerosol generating substrate occurs primarily by conduction and heating of the aerosol generating substrate by convection is minimized or reduced. Therefore, with continuous heat sources, it is particularly important to optimize heat transfer by conduction between the heat source and the aerosol-forming substrate. It has been found that the use of a second heat transfer element has a particularly advantageous effect on the smoking quality of aerosol generating articles containing continuous heat sources if there is no or little compensatory heating effect due to convection.

In the aerosol generating articles of the invention comprising continuous heat sources, a non-combustible heat transfer element may be provided between the downstream end of the heat source and the upstream end of the aerosol generating substrate. The heat transfer element may be made from any of the heat transfer materials described herein in connection with the first and second heat transfer elements. Preferably, the heat transfer element is made of metal foil, most preferably aluminum foil. In addition to optimizing heat transfer by conduction from the heat source to the aerosol generating substrate, the heat transfer element can also reduce or prevent movement of particles and combustion gases from the heat source to the mouth end of the aerosol generating article.

Preferably, the aerosol-forming substrate comprises at least one aerosol-forming agent and at least one material capable of responding to heat by releasing volatile compounds.

The at least one aerosol forming agent may be any suitable known compounds or mixtures of compounds which, when used, promote the formation of a dense and stable aerosol. The aerosol generating agent is preferably 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. Preferred aerosol generating agents for use in the aerosol generating articles of the invention are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1,3-butanediol, and most preferably glycerol.

Preferably, the material capable of releasing volatile compounds when heated is a filler material of plant origin, more preferably a filler of homogenized material of plant origin. 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, fragrances, binders, and mixtures thereof. Preferably, the material of plant origin mainly consists of tobacco material, most preferably homogenized tobacco material.

Preferably, the aerosol forming substrate has a length of from about 5 millimeters to about 20 millimeters, more preferably from about 8 millimeters to 12 millimeters. Preferably, the front portion of the aerosol generating substrate, surrounded by the first thermally conductive element, has a length in the range of about 2 millimeters to about 10 millimeters, more preferably a length in the range of about 3 millimeters to about 8 millimeters, most preferably a length in the range of about 4 millimeters to approximately 6 millimeters. Preferably, the back portion of the aerosol generating substrate, not surrounded by the first thermally conductive element, has a length of from about 3 millimeters to about 10 millimeters. In other words, the aerosol-forming substrate preferably extends downstream of the first thermally conductive element in the range of about 3 millimeters to about 10 millimeters. More preferably, the aerosol-forming substrate extends downstream beyond the first heat transfer element by at least about 4 millimeters.

The heat source and the aerosol-generating substrate of the aerosol-generating articles of the invention can substantially abut each other. Alternatively, the heat source and the aerosol generating substrate of the aerosol generating articles according to the invention can be spaced apart in the longitudinal direction.

Preferably, the aerosol generating articles of the invention comprise an airflow guiding element located downstream of the aerosol generating substrate. The element for directing the air flow determines the path of the air flow through the product that generates the aerosol. The at least one air inlet is preferably provided between the downstream end of the aerosol generating substrate and the downstream end of the airflow guide element. The air flow guide member directs air from at least one inlet to the mouth end of the aerosol generating article.

The element for guiding the air flow may comprise a substantially airtight hollow body with open ends. In such embodiments, air drawn in through the at least one air inlet is first drawn upstream along the outside of the substantially airtight open-ended hollow body and then downstream through the interior of the substantially airtight open-ended hollow body.

The substantially airtight hollow body may be formed from one or more suitable airtight materials that are substantially thermally stable at the temperature of the aerosol generated by heat transfer from the heat source to the aerosol forming substrate. Suitable materials are known in the art and include, but are not limited to, cardboard, plastics, ceramics, and combinations thereof.

In one preferred embodiment, the substantially airtight hollow body with open ends is a cylinder, preferably a straight cylinder of circular cross section.

In another preferred embodiment, the substantially airtight hollow body with open ends is a truncated cone, preferably a truncated straight cone of circular cross section.

The substantially airtight hollow body with open ends may have a length of from about 7 millimeters to about 50 millimeters, for example, a length of from about 10 millimeters to about 45 millimeters, or from about 15 millimeters to about 30 millimeters. The air flow element may have other lengths depending on the desired length of the aerosol generating article and the presence and length of other components in the smoking article.

If the substantially airtight open-ended hollow body is a cylinder, then the cylinder may have a diameter of from about 2 millimeters to about 5 millimeters, such as a diameter of from about 2.5 millimeters to about 4.5 millimeters. The cylinder may have other diameters depending on the desired overall diameter of the smoking article.

If the substantially airtight open-ended hollow body is a frustocone, the upstream end of the frustocone may have a diameter of from about 2 millimeters to about 5 millimeters, such as a diameter of from about 2.5 millimeters to about 4.5 millimeters. The upstream end of the truncated cone may have other diameters depending on the desired overall diameter of the aerosol generating article.

If the substantially airtight open-ended hollow body is a frustocone, the downstream end of the frustocone may have a diameter of from about 5 millimeters to about 9 millimeters, for example, from about 7 millimeters to about 8 millimeters. The downstream end of the truncated cone may have other diameters depending on the desired overall diameter of the aerosol generating article. Preferably, the downstream end of the truncated cone is substantially the same diameter as the aerosol generating substrate.

The substantially airtight hollow body with open ends can abut against an aerosol generating substrate. Alternatively, a substantially airtight hollow body with open ends may extend into the interior of the aerosol generating substrate. For example, in certain embodiments, the substantially airtight hollow body with open ends can extend up to 0.5L into the aerosol generating substrate, where L is the length of the aerosol generating substrate.

The upstream end of the substantially airtight hollow body has a reduced diameter compared to the aerosol generating substrate.

In certain embodiments, the downstream end of the substantially airtight hollow body has a reduced diameter compared to the aerosol generating substrate.

In other embodiments, the downstream end of the substantially airtight hollow body is substantially the same diameter as the aerosol generating substrate.

If the downstream end of the substantially airtight hollow body has a reduced diameter compared to the aerosol forming substrate, the substantially airtight hollow body may be surrounded by a substantially airtight seal. In these embodiments, a substantially airtight seal is located downstream of one or more air inlets. The substantially airtight seal may be substantially the same diameter as the aerosol generating substrate. For example, in some embodiments, the downstream end of the substantially airtight hollow body may be surrounded by a substantially impermeable rod or disk substantially the same diameter as the aerosol generating substrate.

The substantially airtight seal may be formed from one or more suitable impermeable materials that are substantially thermally stable at the temperature of the aerosol generated by heat transfer from the heat source to the aerosol generating substrate. Suitable materials are known in the art and include, but are not limited to, cardboard, plastic, wax, silicone, ceramic, and combinations thereof.

At least a portion of the length of the substantially airtight open-ended hollow body may be surrounded by an air-permeable nebulizer. The breathable atomizer may be substantially the same diameter as the aerosol generating substrate. The breathable atomizer may be formed from one or more suitable breathable materials that are substantially thermally stable at the temperature of the aerosol formed by transferring heat from a heat source to the aerosol forming substrate. Suitable breathable materials are well known in the art and include, but are not limited to, porous materials such as, for example, cellulose acetate, cotton, open-cell ceramic and polymeric foams, tobacco material, and combinations thereof.

In one preferred embodiment, the air flow element comprises a substantially airtight hollow tube with open ends of smaller diameter compared to the aerosol forming substrate and an annular substantially airtight seal of substantially the same outer diameter as the aerosol forming substrate, which surrounds the downstream end of the hollow tube.

The element for directing the air flow may further comprise an inner wrapper surrounding the hollow tube and an annular substantially airtight seal.

The open upstream end of the hollow tube may abut against the downstream end of the aerosol generating substrate. Alternatively, the open upstream end of the hollow tube may be inserted or otherwise extended into the downstream end of the aerosol generating substrate.

The airflow guiding element may further comprise an annular air-permeable atomizer of substantially the same outer diameter as the aerosol-forming substrate surrounding at least a portion of the length of the hollow tube upstream of the annular substantially airtight seal. For example, the hollow tube may be at least partially incorporated into a cellulose acetate fiber plug.

In yet another preferred embodiment, the air flow element comprises: a substantially airtight open-ended truncated hollow cone having an upstream end of smaller diameter compared to the aerosol generating substrate and a downstream end of substantially the same diameter , which is the substrate that forms the aerosol.

The open upstream end of the truncated hollow cone may abut against the downstream end of the aerosol generating substrate. Alternatively, the open upstream end of the truncated hollow cone may be inserted or otherwise extended into the downstream end of the aerosol generating substrate.

The element for directing the air flow may further comprise an annular air-permeable atomizer of essentially the same outer diameter as the aerosol-forming substrate surrounding at least part of the length of the truncated hollow cone. For example, the truncated hollow cone may be at least partially incorporated into the cellulose acetate fiber plug.

The aerosol generating articles according to the invention preferably further comprise an expansion chamber downstream of the aerosol generating substrate and downstream of the airflow guiding element, if present. The presence of the expansion chamber advantageously allows additional cooling of the aerosol generated by heat transfer from the heat source to the aerosol-forming substrate. The expansion chamber also advantageously allows the entire length of the aerosol generating articles according to the invention to be adjusted to the desired value, for example to a length similar to that of conventional cigarettes, by appropriately selecting the length of the expansion chamber. Preferably, the expansion chamber is an elongated hollow tube.

The aerosol generating articles of the invention may also further comprise a mouthpiece downstream of the aerosol generating substrate and downstream of the airflow guide and expansion chamber, if any. The mouthpiece may contain, for example, a filter made from cellulose acetate, paper, or other suitable known filter materials. Preferably, the mouthpiece has a low filtration efficiency, more preferably a very low filtration efficiency. Alternatively or in addition, the mouthpiece may contain one or more segments containing absorbents, adsorbents, flavors and other aerosol modifiers and additives used in traditional cigarette filters, or combinations thereof.

The assembly of the aerosol generating articles according to the invention can be carried out using known methods and equipment.

Method for determining the emissivity coefficient

The emissivity is measured in accordance with the test procedure detailed in ISO 18434-1. This test method uses a reference material with a known emissivity to determine the unknown emissivity of the sample material. Specifically, a reference material is applied over a portion of the sample material and both materials are heated to 100 degrees Celsius. The surface temperature of the reference material is then measured with an infrared camera and the camera system is calibrated using the known emissivity of the reference material. A suitable reference material is black PVC electrical tape, such as black Scotch® 33 electrical tape, which has an emissivity of 0.95. After calibrating the system using the reference material, the infrared camera is moved to measure the surface temperature of the sample material. The emissivity value in the system is corrected until the measured surface temperature of the sample material matches the actual surface temperature of the sample material, which is equal to the surface temperature of the reference material. The emissivity value at which the measured surface temperature matches the actual surface temperature is the true emissivity value for the sample material.

Embodiments and examples

The invention will now be described in more detail, by way of example only, with reference to the accompanying figures, in which:

in fig. 1 is a cross-sectional view of an aerosol generating article according to the present invention;

in fig. 2 shows a test setup for determining the effect of various second thermal conductive elements on heat loss from an aerosol generating article;

in fig. 3 shows the outer surface temperature as a function of time for different materials of the second heat-conducting element when tested on the setup shown in FIG. 2;

in fig. 4 shows the internal temperature as a function of time for different materials of the second thermal element when tested on the apparatus shown in FIG. 2;

in fig. 5 shows the internal temperature as a function of time for the second heat conductive elements when tested on the apparatus shown in FIG. 2 to show the effect of different embossing patterns;

in fig. 6 shows the internal temperature as a function of time for the second heat conductive elements when tested on the apparatus shown in FIG. 2 to show the effect of different surface treatments;

in fig. 7 summarizes the measured emissivity values for various embossing patterns and various surface coatings used in the tests, which are reflected in FIG. 5 and 6;

in fig. 8 and 9 show test data for the aerosol generating articles containing the second heat transfer elements with different surface coatings of FIG. 6, and smoked under Health Canada's heavy smoking regimen; and

in fig. Figures 10 and 11 compare test data for aerosol-generating products containing calcium carbonate surface-coated second heat-conducting elements smoked under a Health Canada heavy smoking regimen.

The aerosol generating article 2 shown in FIG. 1 comprises a combustible carbonaceous heat source 4, an aerosol forming substrate 6, an airflow guide element 44, an elongated expansion chamber 8 and a mouthpiece 10 which are adjacent to each other in coaxial alignment. The combustible carbonaceous heat source 4, the aerosol forming substrate 6, the airflow guide member 44, the expansion chamber 8 and the mouthpiece 10 are wrapped with a low air permeability cigarette paper 12 outer wrapper.

As shown in FIG. 1, a non-combustible, gas-resistant, first barrier coating 14 is provided on substantially the entire rear surface of the combustible carbonaceous heat source 4. In an alternative embodiment, the non-combustible, substantially air-tight first baffle is provided in the form of a disc abutting the rear surface of the combustible carbonaceous heat source 4 and the front surface of the aerosol generating substrate 6.

The combustible carbonaceous heat source 4 is a continuous heat source such that the air drawn through the aerosol generating article for inhalation by the user does not pass through any air flow channels along the combustible heat source 4 .

The aerosol generating substrate 6 is located immediately downstream of the combustible carbonaceous heat source 4 and comprises a cylindrical tobacco material stick 18 containing glycerol as an aerosol generating agent and surrounded by a filter plug wrap 20 .

The heat-conducting component comprises a first heat-conducting element 22, consisting of an aluminum foil tube, surrounds and is in contact with the downstream portion 4b of the combustible carbon-containing heat source 4, and is also adjacent to the upstream portion 6a of the aerosol-forming substrate 6. As shown in FIG. 1, the downstream portion of the aerosol forming substrate 6 is not surrounded by the first heat transfer element 22.

The airflow guide element 44 is located downstream of the aerosol generating substrate 6 and comprises a substantially airtight hollow tube 56 with open ends, made of for example cardboard, having a smaller diameter compared to the aerosol generating substrate 6. The upstream end of the open-ended hollow tube 56 is adjacent to the aerosol generating substrate 6. The downstream end of the open-ended hollow tube 56 is surrounded by an annular, substantially air-tight seal 58 of substantially the same diameter as the aerosol-generating substrate 6. The remainder of the hollow tube with open ends is included in a cylindrical plug of cellulose acetate fiber 60 of substantially the same diameter as the aerosol forming substrate 6.

The open-ended hollow tube 56 and the cylindrical cellulose acetate fiber plug 60 are surrounded by a breathable inner wrap 50. The outer wrap 12 and the inner wrap 50 are provided circumferentially with a series of air inlets 52.

An elongated expansion chamber 8 is positioned downstream of the air flow guide element 44 and includes a cylindrical tube 24 of cardboard with open ends. The mouthpiece 10 of the aerosol generating article 2 is located downstream of the expansion chamber 8 and comprises a cylindrical plug 26 of very low filtering cellulose acetate tow surrounded by a filter plug wrap 28 . The mouthpiece 10 may be surrounded by rim paper (not shown).

The thermally conductive component further comprises a second thermally conductive element 30, consisting of an aluminum foil tube that surrounds and is in contact with the outer wrapper 12. The second thermally conductive element 30 is located on top of the first thermally conductive element 22 and has the same dimensions as the first thermally conductive element 22. Therefore, the second thermal element 30 lies directly on top of the first thermal element 22 with the outer wrapper 12 therebetween. The outer surface of the second thermal element 30 is covered with a surface coating, such as a glossy color coating, which gives an emissivity value of less than about 0.6, preferably less than about 0.2, for the outer surface of the second thermal element 22.

In use, the user ignites the combustible carbon-containing heat source 4, which heats the aerosol-forming substrate 6 by heat conduction. The user then puffs through the mouthpiece 10 so that cold air is drawn into the aerosol generating article 2 through the air inlets 52. The drawn air passes upstream between the outer portion of the hollow tube 56 with open ends and the inner wrap 50 through the cylindrical rod of cellulose acetate fiber 60 to the aerosol forming substrate 6. Heating the aerosol generating substrate 6 causes the release of volatile and semi-volatile compounds and glycerol from the tobacco material 18, which are entrained in the drawn air as it reaches the aerosol forming substrate 6. The drawn-in air is also heated as it passes through the heated aerosol-forming substrate 6. The heated intake air and entrained connections then pass downstream through the inside of the hollow tube 56 of the airflow element 44 to the expansion chamber 8 where they cool and condense. The cooled aerosol then passes downstream through the mouthpiece 10 of the aerosol generating article 2 into the user's mouth.

A non-combustible, substantially airtight barrier coating 14 provided on the entire rear surface of the combustible carbonaceous heat source 4 isolates the combustible carbonaceous heat source 4 from the airflow passages passing through the aerosol generating article 2 so that, in use, the air drawn through the article 2 , generating aerosol, through the air flow passages, does not directly come into contact with the combustible carbon-containing heat source 4 .

The second heat transfer element 30 retains heat within the aerosol generating article 2, helping to maintain the temperature of the first heat transfer element 22 during smoking. This, in turn, helps to maintain the temperature of the aerosol forming substrate 6, which contributes to a prolonged and improved delivery of the aerosol.

In FIG. 2 shows a test setup 100 for reproducing the heating of an aerosol generating article in accordance with the present invention, which is used to test the performance of various second thermal conductive elements, including those with different surface treatments. The test rig 100 includes a cylindrical aluminum body 102 around which the test material 104 is wrapped. The test material 104 reproduces the second thermally conductive element in the aerosol generating article of the invention.

During the test, a coil heater 106 built into the aluminum housing 102 reproduces the effect of heating a combustible heat source at the upstream end of the aerosol generating article. In order to be able to measure the emissivity of the outer surface of the test material 104 in accordance with ISO 18434-1, the voltage on the heater coil 106 is gradually increased, providing periods of stabilized elevated temperature during the heating process. In particular, the voltage at the coil heater 106 is gradually increased to 6 volts, 11 volts, 14 volts, 17 volts, 19.5 volts, 21 volts, and 24 volts with a delay of 10 minutes after each increase in voltage, so that the temperature of the test material 104 stabilizes.

During the test procedure, the first and second thermocouples 108 and 110 record the temperature on the outer surface of the test material 104 and inside the aluminum housing 102, respectively. Each thermocouple 108, 110 is located 7 millimeters from the upstream end 112 of the aluminum housing 102.

In FIG. 3 shows the surface temperature measured by thermocouple 108 versus time for different materials of the second thermal element when tested on the setup shown in FIG. 2. The materials tested for the second thermal element were: aluminum without additives; paper without additives; paper-aluminum colaminate, in which the aluminum layer forms the outer surface; and paper-aluminum colaminate, in which the paper layer forms the outer surface. The aluminum had a measured emissivity of 0.09 and the paper had a measured emissivity of 0.95. In FIG. 3 shows that the lower emissivity of the aluminum layer compared to the paper layer gave a higher external surface temperature of the second heat-conducting element due to reduced heat loss by radiation.

As shown in FIG. 4, which illustrates the internal temperature versus time measured with thermocouple 110 during the same test as in FIG. 3, the reduction in radiant heat loss achieved by using a second low emissivity heat transfer element on the outer surface also results in an increase in the internal temperature in the reproduced aerosol generating article. Based on these data, the present inventors have determined that the use of a second low emissivity heat transfer element on the outer surface provides a more thermally efficient aerosol generating article and therefore produces a desired increase in core temperature during smoking.

The heat test was repeated using three different paper-aluminum colaminates, each with a different embossing pattern, and in each case the aluminum layer formed the outer surface of the second heat transfer element. The test data is shown in Fig. 5, which shows the internal temperature measured by thermocouple 110 versus time for all three materials tested, and for comparison, data for unembossed colaminate (in both cases, aluminum and paper formed the outer surface). The data in FIG. 5 show that the embossing of the material constituting the second thermally conductive element does not substantially affect the internal temperature of the reproducible aerosol generating article in the heat test, which may be because the embossing does not substantially affect the emissivity on the outer surface of the second heat transfer element. This is shown by the data in Fig. 7 which shows that the measured emissivity values for the three embossing patterns were 0.092, 0.085 and 0.092, which is essentially the same as the emissivity value of 0.09 for an unembossed colaminate in which the aluminum layer forms the outer surface.

The heat test was repeated again using six different paper-aluminum colaminates, each having a different surface coating of colored paints applied over the outer surface of the aluminum layer, and in each case the aluminum layer formed the outer surface of the second thermal element. The six different surface finishes tested were: glossy gold; matte pink; glossy pink; matte green; glossy orange and matte black. The test data is shown in Fig. 6, which shows the internal temperature measured by thermocouple 110 versus time for all six tested materials, and for comparison, data for uncoated colaminate (in both cases, aluminum and paper formed the outer surface). In FIG. 6 shows that coating the aluminum layer with a matte black paint gave an internal temperature during the test which was the same as the temperature obtained when the colaminate paper layer formed the outer surface of the second heat transfer element. The remaining inks did not have a significant effect on the internal temperature of the reproducible aerosol generating article compared to the data obtained for the uncoated aluminum layer forming the outer surface of the second heat transfer element. Therefore, based on these data, the inventors of the present invention have determined that the application of a surface coating to the material forming the outer surface of the second thermal element can have a significant impact on the thermal performance of the second thermal element, depending on which particular surface coating is used.

In this regard, the emissivity of the various test materials that were used in the test in FIG. 6 and the resulting data is shown in FIG. 7. In FIG. 7 that although the color coating of the aluminum layer improves the emissivity compared to the uncoated aluminum layer, the effect was most significant when the coating was matte black. Accordingly, there is a direct relationship between the increase in the emissivity value resulting from the application of the color coating and the resulting decrease in the internal temperature of the reproducible aerosol generating article during the heat test. Accordingly, the inventors of the present invention have determined that when applying a surface coating to the outer surface of the second heat transfer element, the surface coating should be selected so as to maintain or provide a low value of emissivity in order to prevent an undesirable decrease, or achieve a desired increase, in the internal temperature of the article generating aerosol while smoking.

The aerosol generating articles were made using the six coated colaminates used in the tests in FIG. 6 and 7, in each case the coated aluminum layer forming the outer surface of the second heat transfer element. For comparison, an aerosol-generating article was also made using paper-aluminum colaminate, where the outer surface of the second heat-conducting element was formed by an uncoated matte aluminum layer. In each case, the colaminate contained a paper layer 73 micrometers thick and 45 grams per square meter, laminated to aluminum foil 6.3 micrometers thick. The aerosol-generating products were then smoked according to Health Canada's heavy duty smoking regimen (puff volume 55 cc, puff frequency 30 seconds, duration per puff 2 seconds), and data obtained from delivery of glycerol, nicotine, and total particulate matter ( TPM) are shown in FIG. 8 and 9.

In FIG. 8 and 9 show that matte pink, matte green, glossy pink and glossy orange finishes resulted in the same delivery of glycerine, nicotine and TPM as the reference uncoated brushed aluminum product. The glossy gold plating resulted in reduced but acceptable shipping compared to the reference product. The matte black finish resulted in a significantly reduced and unacceptable delivery compared to the reference product. Based on the data in FIG. 8 and 9 in combination with measured emissivity values in FIG. 7, the present inventors have determined that when providing a surface treatment on the outer surface of the material constituting the second thermally conductive element, the surface treatment should be chosen to maintain or provide an emissivity of less than about 0.6.

In an additional example, aerosol generating articles were made to study the effect of a calcium carbonate coating on the outer surface of a second heat transfer element. Sets of first and second reference articles were made, each containing an uncoated second thermal element, and then smoked according to Health Canada's heavy smoking regimen (puff volume 55 cc, puff frequency 30 seconds, single puff duration 2 seconds). ). Temperature profiles during smoking for the first and second reference articles are shown in FIG. 10 and 11 (FIG. 10 shows the temperature measured at the downstream end of the heat source and FIG. 11 shows the temperature measured at the upstream end of the aerosol forming substrate). Each of the second reference articles contains a heat source that provides for greater heat transfer than the heat source of each of the first reference articles. As a consequence, the second reference articles exhibit a generally hotter temperature profile than the first reference articles.

For comparison, a set of third products was made, where each product is identical to the second reference products with the difference that a lacquer coating is added to the outer surface of the second heat-conducting elements, and the lacquer contains 60 percent calcium carbonate. Then, a set of third articles were smoked according to the same smoking regime, and the results are shown in FIG. 10 and 11. As shown in FIG. 10 and 11, coating with calcium carbonate on the outer surface of the second heat-conducting elements of the second reference articles modifies the temperature profiles of the second reference articles during smoking so that they approach the temperature profiles of the first reference articles during smoking, despite the greater heat output of the heat source in each. from the second reference products compared with the heat output of the heat source in each of the first reference products.

The embodiments and examples shown in FIG. 1-11 and described in this document, explain the invention, but do not limit it. Other embodiments of the invention may be made without departing from its scope, and it should be understood that the specific embodiments described herein are not intended to be limiting.

Claims (30)

1. An aerosol generating article, comprising: heat source; an aerosol-forming substrate in thermal contact with a heat source; a thermally conductive component placed around at least a portion of the aerosol generating substrate, wherein the thermally conductive component comprises an outer surface constituting at least a portion of the outer surface of the aerosol generating article, wherein at least a portion of the outer surface of the thermally conductive component contains a surface treatment and has an emissivity of less than 0.6. 2. An aerosol generating article according to claim 1, characterized in that the heat source is a combustible heat source. 3. An aerosol generating article according to claim 1 or 2, characterized in that the emissivity of the outer surface of the heat-conducting component is at least one of less than 0.5 and more than 0.1. 4. Product that generates an aerosol, according to any one of paragraphs. 1-3, characterized in that the surface treatment comprises at least one of a surface coating, embossing, blind embossing, and combinations thereof. 5. Product that generates an aerosol, according to any one of paragraphs. 1-3, characterized in that the surface treatment contains a surface coating, and, if necessary, the surface coating contains a coating composition containing a filler material, a binder and a solvent. 6. An aerosol generating article according to claim 5, characterized in that the surface coating comprises a filler material containing one or more materials selected from graphite, metal oxides and metal carbonates. 7. An aerosol generating product according to claim 5 or 6, characterized in that the outer surface of the surface coating has a surface roughness, measured using a Parker-Print-Surface roughness measuring device according to ISO 8791-4, from 0, 1 micrometer to 1 micrometer. 8. Product that generates an aerosol, according to any one of paragraphs. 5-7, characterized in that the surface coating is discontinuous. 9. Product that generates an aerosol, according to any one of paragraphs. 5-8, characterized in that the surface coating contains at least one pigment or a translucent material, or metal particles, or metal plates, or both metal particles and metal plates, or metal foil. 10. An aerosol generating article according to any one of the preceding claims, characterized in that the thermally conductive component comprises a first thermally conductive element placed around and in contact with the downstream portion of the heat source and adjacent to the upstream portion of the aerosol generating substrate, and a second heat-conducting element placed around at least a part of the first heat-conducting element and containing an outer surface constituting at least a portion of the outer surface of the aerosol-generating article. 11. An aerosol-generating article according to claim 10, characterized in that the second heat-conducting element is radially separated from the first heat-conducting element by at least one layer of heat-insulating material that extends around at least part of the first heat-conducting element between the first and second heat-conducting elements. elements. 12. An aerosol generating article according to claim 10 or 11, characterized in that the second thermally conductive element is part of a multilayer or layered material containing the second thermally conductive element in combination with one or more thermally insulating layers. 13. Product that generates an aerosol, according to any one of paragraphs. 10-12, characterized in that the second heat-conducting element is made in the form of a layered material containing at least one heat-insulating layer layered on the second heat-conducting element, and the heat-insulating layer forms an inner layer of the laminated material adjacent to the first heat-conducting element. 14. Product that generates an aerosol, according to any one of paragraphs. 10-13, characterized in that the second heat-conducting element is a two-layer layered material, which includes an outer layer of aluminum and an inner layer of paper. 15. Product that generates an aerosol, according to any one of paragraphs. 10-14, characterized in that it additionally contains one or more separating elements between the first heat-conducting element and the second heat-conducting element to maintain a certain interval between them. 16. An aerosol generating article according to any one of the preceding claims, characterized in that it contains an aerosol generating agent and a material capable of reacting to heat by releasing volatile compounds. 17. A method of manufacturing an article that generates an aerosol containing a heat source, a substrate that forms an aerosol in thermal contact with a heat source, and a heat-conducting component placed around at least a portion of the substrate that generates an aerosol, and the heat-conducting component contains an outer surface that is at least a portion of the outer surface of the aerosol generating article, wherein the method includes the step of applying a surface treatment to at least a portion of an outer surface of the thermally conductive component such that the treated portion of the thermally conductive component has an emissivity of less than 0.6. 18. The method according to claim 17, characterized in that the heat source is a combustible heat source. 19. The method according to claim 17 or 18, characterized in that the emissivity of the outer surface of the heat-conducting component is at least one of less than 0.5 and more than 0.1. 20. The method according to any one of paragraphs. 17-19, characterized in that the surface treatment comprises at least one of surface coating, embossing, blind embossing, and combinations thereof. 21. The method according to any one of paragraphs. 17-19, characterized in that the surface treatment contains a surface coating, and the surface coating contains a coating composition containing a filler material, a binder and a solvent, and, if necessary, the filler material contains one or more materials selected from graphite, oxides metals and metal carbonates. 22. The method according to claim. 20 or 21, characterized in that the outer surface of the surface coating has a roughness of the surface coating, measured using a device for measuring the roughness "Parker-Print-Surface" according to ISO 8791-4, from 0.1 micrometer to 1 micrometer. 23. The method according to any one of paragraphs. 20-22, characterized in that the surface coating is discontinuous. 24. The method according to any one of paragraphs. 20-23, characterized in that the surface coating contains at least one pigment or a translucent material, or metal particles, or metal plates, or both metal particles and metal plates, or metal foil. 25. The method according to any one of paragraphs. 17-24, characterized in that the aerosol-forming substrate contains an aerosol-forming agent and a material capable of reacting to heat by releasing volatile compounds.

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