WO2014013054A2

WO2014013054A2 - Smoking article having reduced sidestream smoke

Info

Publication number: WO2014013054A2
Application number: PCT/EP2013/065282
Authority: WO
Inventors: John Faulkner; Sebastien LANASPEZE
Original assignee: Philip Morris Products S.A.
Priority date: 2012-07-19
Filing date: 2013-07-19
Publication date: 2014-01-23
Also published as: TW201410163A; WO2014013054A3; AR091833A1

Abstract

The present invention relates to a smoking article having reduced sidestream smoke. As such, a smoking article having a mouth-end and a distal-end is provided. The smoking article comprises: a combustible heat source; an aerosol-forming substrate; at least one air inlet downstream of the aerosol-forming substrate; and an airflow pathway extending between the at least one air inlet and the mouth-end of the smoking article, wherein the airflow pathway comprises a first portion extending upstream from the at least one air inlet towards the aerosol-forming substrate and a second portion extending longitudinally downstream from the first portion towards the mouth-end of the smoking article, wherein the first portion is configured such that it has a component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article. The invention also relates to a method for reducing the sidestream smoke produced by such a smoking article during use.

Description

SMOKING ARTICLE HAVING REDUCED SIDESTREAM SMOKE

The present invention relates to a smoking article having reduced sidestream smoke. In particular, the invention relates to smoking articles in which tobacco is heated rather than combusted. The invention also relates to a method for reducing the sidestream smoke produced by a smoking article during use.

A number of smoking articles in which tobacco is heated rather than combusted have been proposed in the art. One aim of such 'heated' smoking articles is to reduce known harmful smoke constituents of the type produced by the combustion and pyrolytic degradation of tobacco in conventional cigarettes. In one known type of heated smoking article, an aerosol is generated by the transfer of heat from a combustible heat source to an aerosol-forming substrate located 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 entrained in air drawn through the smoking article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user.

For example, WO-A2-2009/022232 discloses a smoking article comprising a combustible heat source, an aerosol-forming substrate downstream of the combustible heat source, and a heat-conducting element around and in direct contact with a rear portion of the combustible heat source and an adjacent front portion of the aerosol-forming substrate. The combustible heat source has a through hole to provide an airflow pathway through the heated aerosol-forming substrate to the mouth-end of the smoking article. However, providing such a through hole may result in the penetration of the lighter flame into the heat source during lighting of the smoking article. This may lead to combustion of the aerosol- forming substrate, which is undesired.

In smoking articles, particularly where the aerosol-forming substrate is heated between puffs, aerosol may form leading to visible sidestream smoke when the user is not puffing on the smoking article.

It would therefore be desirable to provide a heated smoking article with reduced sidestream smoke.

According to the present invention, there is provided a smoking article having a mouth- end and a distal-end. The smoking article comprises: a combustible heat source; an aerosol-forming substrate; at least one air inlet downstream of the aerosol-forming substrate; and an airflow pathway extending between the at least one air inlet and the mouth-end of the smoking article, wherein the airflow pathway comprises a first portion extending upstream from the at least one air inlet towards the aerosol-forming substrate and a second portion extending longitudinally downstream from the first portion towards the mouth-end of the smoking article, wherein the first portion is configured such that it has a component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article.

By providing an airflow pathway having such a first portion, a smoking article is provided that enables condensation and/or absorption of the aerosol released by the aerosol-forming substrate in between puffs, thus reducing the emission of sidestream smoke.

As used herein, the term 'airflow pathway' is used to describe a route along which air may be drawn through the smoking article for inhalation by a user. The terms 'upstream' and 'downstream' relate to the relative position along the 'airflow pathway'. The term 'front' relates to a relative position closer to the combustible heat source than the mouth-end of the smoking article, and the term 'rear' relates to a relative position closer to the mouth-end of the smoking article than the combustible heat source.

As used herein, the term 'longitudinal' refers to a direction from the mouth-end of the smoking article to the combustible heat source end of the smoking article. The term 'length' is used to describe the dimension in the longitudinal direction of the smoking article.

As used herein, the term 'aerosol-forming substrate' is used to describe a substrate capable of releasing upon heating volatile compounds, which can form an aerosol. The aerosols generated from aerosol-forming substrates of smoking articles according to the invention may be visible or invisible and may include vapours (for example, fine particles of substances, which are in a gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours.

The first portion of the airflow pathway is configured to have component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article. By providing such a configuration of the first portion, the released aerosols follow a longer airflow pathway than would be provided by an airflow pathway having only a straight line from the air inlet to the aerosol- forming substrate, thereby providing more time for condensate to form and/or for absorption of the aerosol to occur, and reducing sidestream smoke when the user is not puffing on the smoking article.

To increase the time for condensate to form and/or for absorption to occur, the first portion may form a tortuous airflow pathway between the air inlet and the aerosol-forming substrate. As used herein, the term 'tortuous' connotes that the airflow pathway has repeated turns or bends, e.g. it winds or twists between the air inlet and the aerosol-forming substrate. In a preferred embodiment, the first portion forms a helical airflow pathway. Preferably, the axis of the helical pathway is substantially coincident with the longitudinal axis of the smoking article.

The first portion of the airflow pathway preferably at least partially surrounds the second portion of the airflow pathway. In this way, the first portion of the airflow pathway is preferably formed around the second portion of the airflow pathway. Thus, the first portion of the airflow pathway is preferably configured to extend along an outer portion of the smoking article from the air inlet to the aerosol-forming substrate, and the second portion is preferably configured to extend along an inner portion of the smoking article from the aerosol-forming substrate to the mouth-end of the smoking article. Thus, the first portion of the airflow pathway is preferably configured to be longer than the second portion of the airflow pathway.

The second portion of the airflow pathway preferably extends longitudinally from a location in, around, or near the aerosol-forming substrate substantially adjacent the combustible heat source to the mouth-end of the smoking article. Preferably, the second portion of the airflow pathway does not have a component of direction perpendicular to the longitudinal axis of the smoking article. Preferably, the second portion is linear. The second portion is preferably shorter than the first portion. The second portion of the airflow pathway is preferably configured to reduce the amount of condensation that occurs before the user inhales the aerosol.

Preferably, the smoking article comprises an airflow directing element to achieve an airflow pathway as described above. The airflow directing element is preferably downstream of the aerosol-forming substrate, and the element preferably defines the first portion of the airflow pathway and the second portion of the airflow pathway. The airflow directing element preferably comprises an open-ended, substantially air impermeable hollow body. The hollow body has a first end configured to be near or adjacent to the mouth-end of the smoking article, and a second end configured to be near or adjacent to the aerosol-forming substrate. The hollow body is preferably a right circular cylinder.

The second portion of the airflow pathway is preferably bounded by the inner surface of the hollow body. The first portion of the airflow pathway is preferably formed by a channel on the outer surface of the hollow body. An open channel is preferably formed by wrapping material around the outer surface of the hollow body. The material is preferably wrapped to form a helical shaped channel along the outer surface of the hollow body. The material is preferably elongate, and preferably has a thickness of between about 0.1 mm and about 0.4 mm, more preferably between about 0.2 mm and about 0.3 mm. The material preferably has a width between about 10 mm and about 15 mm. The material is preferably cardboard, or any other suitable material. The open channel is preferably closed by wrapping the hollow body and the elongate material in a wrapper material. Preferably, the wrapper material is substantially air impermeable.

The air inlets are preferably arranged circumferentially around the wrapper material.

As used herein, the term 'air inlet' is used to describe one or more holes, slits, slots or other apertures in the outer wrapper and any other materials circumscribing components of smoking articles according to the invention through which air may be drawn into the one or more airflow pathways. The air inlets are preferably holes in the wrapper material. The holes are preferably substantially equally spaced about the circumference of the airflow directing element. A collar is preferably provided around the first end of the hollow body. The collar is preferably substantially air impermeable, and is configured to substantially prevent air from flowing directly from the air inlets to the mouth-end without passing along the airflow pathway. The collar is preferably wrapped in the wrapper material.

The combustible heat source is preferably upstream from the aerosol-forming substrate. The heat source may be in the form of a blade that is configured to be inserted into the aerosol-forming substrate. Alternatively, the heat source may be configured to surround the aerosol-forming substrate, and as such may be in the form of a hollow cylinder, or any other such suitable form.

The combustible heat source is preferably a carbonaceous heat source. As used herein, the term 'carbonaceous' is used to describe a combustible heat source comprising carbon.

In a preferred embodiment, the combustible heat source is cylindrical. Preferably, the combustible heat source is isolated from the airflow pathway such that air drawn along the airflow pathway does not directly contact the combustible heat source. Such a heat source is referred to herein as a 'blind' heat source. The term blind' is used to describe a heat source of a smoking article according to the invention in which air drawn through the smoking article for inhalation by a user does not pass through any airflow channels along the heat source. In certain alternative embodiments, the heat source is 'non-blind'. As used herein, the term 'non-blind' is used to describe a combustible heat source of a smoking article according to the invention in which air drawn through the smoking article for inhalation by a user passes through one or more airflow channels along the combustible heat source.

The combustible heat source has opposed front and rear faces. In embodiments in which the combustible heat source is upstream from aerosol-forming substrate, the combustible heat source preferably has a non-combustible, substantially air impermeable first barrier provided on at least substantially the entire rear face of the combustible heat source. In certain preferred embodiments, the first barrier comprises a first barrier coating provided on a rear face of the combustible heat source. In such embodiments, preferably the first barrier comprises a first barrier coating provided on at least substantially the entire rear face of the combustible heat source. More preferably, the first barrier comprises a first barrier coating provided on the entire rear face of the combustible heat source. The barrier substantially isolates the heat source from the aerosol-forming substrate.

As used herein, the term 'isolated combustible heat source' is used to describe a combustible heat source that does not come into direct contact with air drawn through the smoking article along the one or more airflow pathways.

As used herein, the term 'direct contact' is used to describe contact between air drawn through the smoking article along the airflow pathway and a surface of the heat source.

In addition, the heat source is preferably provided with a barrier wrapped around the circumference of the heat source. A similar barrier may also be wrapped around at least a portion of the aerosol-forming substrate such that heat is more effectively conducted from the heat source to the aerosol-forming substrate.

Preferably, the above-described barrier is provided in the form of a heat-conducting element around and in contact with a rear portion of the heat source and a front portion of the aerosol-forming substrate. Preferably, the portion of the heat-conducting element around the front portion of the aerosol-forming substrate comprises at least one air transfer inlet. Preferably, the first portion of the airflow pathway is between the at least one external air inlet and the at least one air transfer inlet, and the second portion of the airflow pathway is between the at least one air transfer inlet and the mouth-end of the smoking article. Preferably the heat-conducting element is formed from aluminium, or any other suitable heat conducting material.

In one particularly preferred embodiment, the airflow directing element is partially formed by wrapping the elongate material around the hollow body to form the open channel. In addition, the collar is wrapped around the hollow body. The heat source and aerosol- forming substrate are connected together by the heat-conducting element in a separate operation. The partially formed airflow directing element, and the heat source and aerosol- forming substrate are connected together by wrapping both components in the outer wrapper material. In addition, the mouth-end element is connected to the airflow directing element by the wrapper material. In this way, a smoking article of the invention can be formed.

According to a further aspect of the present invention, there is provided, a method of reducing or eliminating smoke from an aerosol-forming substrate of a smoking article in between puffs, the method comprising providing a smoking article comprising: a combustible heat source; an aerosol-forming substrate; at least one external air inlet downstream of the aerosol-forming substrate; and an airflow pathway extending between the at least one external air inlet and the mouth-end of the smoking article, wherein the airflow pathway comprises a first portion extending upstream from the at least one external air inlet towards the aerosol-forming substrate and a second portion extending longitudinally downstream from the first portion towards the mouth end of the smoking article, wherein the first portion is configured such that it has a component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article, such that, in use and in between puffs, smoke generated by heating the aerosol-forming substrate condenses on the walls of the first portion of the airflow pathway as the smoke moves from the aerosol-forming substrate towards the at least one external air inlet.

In between puffs the aerosol (smoke) flows back up the first portion of the airflow pathway from the aerosol-forming substrate towards the external air inlet. The first portion of the airflow pathway is configured to increase condensation of the aerosol (smoke) constituents to reduce the aerosol (smoke) exiting the external air inlets. It is believed that the condensation may increase due to the increased surface area of the airflow pathway along the the increased length of the first portion as compared to a pathway that comprises a straight line between the aerosol-forming substrate and the external air inlets. Furthermore, it is believed that due to the non-linear form of the first portion of the airflow pathway, the condensation of the aerosol (smoke) may increase due to the increased likelihood of impaction of the smoke on the walls of the airflow pathway. Thus, preferably visible aerosol exiting the external air inlet may be reduced.

It will be appreciated that the above described features of the smoking article, where appropriate, may be used in conjunction with the above described method.

The disclosure extends to methods and apparatus substantially as herein described with reference to the accompanying drawings.

As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any feature in one aspect described in the disclosure herein may be applied to other features discussed herein, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some or all features in one aspect can be applied to any, some or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the various features can be implemented or supplied or used independently.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a smoking article according to the present invention; Figures 2(a) and (b) show the airflow pathway during puffing by a user, and when the user is not puffing, respectively;

Figure 3 shows a heat conducting element configured to conduct heat between the heat source and the aerosol-forming substrate; and

Figure 4 shows an example of the airflow directing element, and a means for forming the first and second portions of the airflow pathway.

Figure 1 shows a smoking article 100. The smoking article comprises a combustible heat source 102, an aerosol-forming substrate 104 between which is a heat conducting element 106. The smoking article further comprises a mouth-end element 108, such as a filter element. An airflow directing element 1 10 is provided between the aerosol-forming substrate 104 and the mouth-end element 108. External air inlet holes 1 12 are provided circumferentially around the outer wrapping of the airflow directing element 1 10. A first portion 1 14 of an airflow pathway is provided around the airflow directing element and is provided to guide air from the external air inlet holes 1 12 to the aerosol-forming substrate 104. The first portion is formed as a channel in a helical arrangement around the airflow directing element, and thus the length of the first portion of the airflow pathway is increased as compared to the straight line distance from the external air inlets to the aerosol-forming substrate. A second portion 1 16 of an airflow pathway is provided within the airflow directing element to guide air from the aerosol-forming substrate to the mouth-end of the smoking article. The second portion is formed by the wall of a hollow tube that forms the airflow directing element. As will be described in further detail below, the first portion of the airflow directing element is bounded by the outer surface of the wall forming the hollow tube of the airflow directing element. A substantially air impermeable collar 1 18 is provided between the section of the airflow directing element 1 10 forming the first portion 1 14 of the airflow directing element, and the mouth-end element 108. In use, the collar 1 18 substantially prevents air flowing directly from the external air inlets 1 12 to the mouth-end 108. Air transfer inlets 120 may be provided circumferentially around the heat conducting element 106 to facilitate passing air from the first portion 1 14 of the airflow pathway into the aerosol- forming substrate 104.

Further detail of the operation of the smoking article will now be described with reference to Figures 2. The user puffs on the mouth-end of the smoking article to draw in air which follows the airflow pathway 200 to the mouth-end of the smoking article. As can be seen in Figure 2(a), the air proceeds from the external air inlets 1 12 along the first portion of the airflow pathway 1 14, through the air transfer inlets 120, through the aerosol-forming substrate 104, and then through the second portion 1 16 of the airflow directing element to the mouth-end of the smoking article. Figure 2(b) shows the airflow when the user is not puffing on the smoking article. As can be seen, aerosol continues to be generated because the aerosol-forming substrate is continuously heated by the heat source once the heat source is ignited. As the aerosol proceeds along the first portion of the airflow pathway condensation of the aerosol, absorption or adsorption of the aerosol into the walls of the first portion channel may occur. The increased length of the first portion of the airflow pathway, as described above, provides increased time and surface area of the first portion channel for the aerosol to cool more, condense and/or be absorbed/adsorbed as the aerosol moves from the aerosol-forming substrate to the external air inlets. Thus, the amount of sidestream smoke exiting the external air inlets when the user is not puffing on the smoking article is reduced.

As described above, a heat conducting element is provided between the heat source and the aerosol-forming substrate. The combustible heat source is isolated from the one or more airflow pathways such that, in use, air drawn through the smoking article along the airflow pathway does not directly contact the combustible heat source. The heat conducting element will now be described in further detail with reference to Figure 3. The heat conducting element 106 comprises a first element 300 configured to wrap around the heat source, and a second element 302 configured to wrap around the aerosol-forming substrate. A third element (not shown) is provided between the first and second elements of the heat conducting element to form a barrier between the heat source and the aerosol-forming substrate. The air transfer inlets 120 are provided circumferentially around the second element 302, and in one example four such inlets are provided equally spaced about the circumference. The air transfer inlets may be about 0.5 mm is diameter. In one example, the first element 300 is approximately 8 mm in diameter and approximately 4 mm wide. The second element 302 is approximately 7.3 mm in diameter and approximately 5 mm wide. The heat conducting element may be manufactured from any suitable material but is preferably manufactured from aluminium.

The airflow directing element 1 10 will now be described in further detail with reference to Figure 4. A hollow cylindrical tube 400 is provided which forms the second portion of the airflow pathway. The hollow tube has an external diameter 402 of between about 6 mm and about 7.2 mm and an internal diameter 404 of between about 5.4 mm and about 6.8 mm. The first portion of the airflow pathway is formed by wrapping a long and narrow strip 406 of material is wrapped around the hollow tube 400 in the form of a helix to form an open channel around the outer wall of the hollow tube. The strip 406 has a width 408 of between about 10 mm and about 15 mm. A substantially air impermeable wrapper (not shown) is then wrapped around the hollow tube to form a closed channel which forms the first portion of the air flow pathway. Finally, a plurality of holes are formed circumferentially around the wrapper to form the air inlet holes 1 12. The exemplary embodiments described above are not limiting. Other embodiments consistent with the exemplary embodiments described above will be apparent to those skilled in the art.

Claims

A smoking article having a mouth-end and a distal-end, the smoking article comprising:

a combustible heat source;

an aerosol-forming substrate;

at least one air inlet downstream of the aerosol-forming substrate; and an airflow pathway extending between the at least one air inlet and the mouth-end of the smoking article, wherein the airflow pathway comprises a first portion extending upstream from the at least one air inlet towards the aerosol-forming substrate and a second portion extending longitudinally downstream from the first portion towards the mouth-end of the smoking article, wherein the first portion is configured such that it has a component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article.

A smoking article according to Claim 1 , wherein the first portion forms a tortuous airflow pathway between the air inlet and the aerosol-forming substrate.

A smoking article according to Claim 1 or 2, wherein the first portion forms a helical airflow pathway.

A smoking article according to any of Claims 1 , 2 or 3, wherein the first portion of the airflow pathway at least partially surrounds the second portion of the airflow pathway.

A smoking article according to any of the previous claims, comprising:

an airflow directing element downstream of the aerosol-forming substrate, the airflow directing element defining the first portion of the airflow pathway and the second portion of the airflow pathway.

A smoking article according to Claim 5 wherein the airflow directing element comprises an open-ended, substantially air impermeable hollow body.

A smoking article according to Claim 6 wherein the hollow body is a right circular cylinder. A smoking article according to Claim 6 or 7, wherein the first portion of the airflow pathway is formed by a channel on the outer surface of the hollow body.

A smoking article according to any of Claims 6, 7 or 8, wherein the second portion of the airflow pathway is bounded by the inner surface of the hollow body.

A smoking article according to any of the preceding claims, wherein the combustible heat source is isolated from the airflow pathway such that air drawn along the airflow pathway does not directly contact the combustible heat source.

A smoking article according to any preceding claim further comprising:

a heat-conducting element around and in contact with a rear portion of the combustible heat source and a front portion of the aerosol-forming substrate.

A smoking article according to Claim 1 1 , wherein the portion of the heat-conducting element around the front portion of the aerosol-forming substrate comprises at least one air transfer inlet.

A smoking article according to Claim 12, wherein the first portion of the airflow pathway is between the at least one air inlet and the at least one air transfer inlet, and the second portion of the airflow pathway is between the at least one air transfer inlet and the mouth-end of the smoking article.

A method of reducing or eliminating smoke from an aerosol-forming substrate of a smoking article in between puffs, the method comprising providing a smoking article comprising:

a combustible heat source;

an aerosol-forming substrate;

at least one air inlet downstream of the aerosol-forming substrate; and an airflow pathway extending between the at least one air inlet and the mouth-end of the smoking article, wherein the airflow pathway comprises a first portion extending upstream from the at least one air inlet towards the aerosol-forming substrate and a second portion extending longitudinally downstream from the first portion towards the mouth end of the smoking article, wherein the first portion is configured such that it has a component of direction perpendicular to the longitudinal axis of the smoking article, and a component of direction parallel to the longitudinal axis of the smoking article, such that, in use and in between puffs, smoke generated by heating the aerosol- forming substrate condenses on the walls of the first portion of the airflow pathway as the smoke moves from the aerosol-forming substrate towards the at least one air inlet.