U.S. patent application number 16/066179 was filed with the patent office on 2019-01-17 for aerosol generating article with ventilation zone.
This patent application is currently assigned to Philip Morris Products S.A.. The applicant listed for this patent is Philip Morris Products S.A.. Invention is credited to Rui Nuno BATISTA, Andrea CARRARO.
Application Number | 20190014813 16/066179 |
Document ID | / |
Family ID | 55027621 |
Filed Date | 2019-01-17 |
![](/patent/app/20190014813/US20190014813A1-20190117-D00000.png)
![](/patent/app/20190014813/US20190014813A1-20190117-D00001.png)
![](/patent/app/20190014813/US20190014813A1-20190117-D00002.png)
![](/patent/app/20190014813/US20190014813A1-20190117-D00003.png)
![](/patent/app/20190014813/US20190014813A1-20190117-D00004.png)
![](/patent/app/20190014813/US20190014813A1-20190117-D00005.png)
United States Patent
Application |
20190014813 |
Kind Code |
A1 |
CARRARO; Andrea ; et
al. |
January 17, 2019 |
AEROSOL GENERATING ARTICLE WITH VENTILATION ZONE
Abstract
An aerosol generating article is provided, including a
combustible heat source; an aerosol forming substrate downstream of
the combustible heat source; and a wrapper circumscribing at least
a rear portion of the combustible heat source and at least a front
portion of the aerosol forming substrate, wherein a plurality of
weakness formations are provided on a region of the wrapper
overlying the combustible heat source, and wherein the wrapper is
rupturable at the plurality of weakness formations and is
configured to form a ventilation zone comprising a plurality of
apertures extending through the wrapper.
Inventors: |
CARRARO; Andrea; (Ins,
CH) ; BATISTA; Rui Nuno; (Morges, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Philip Morris Products S.A. |
Neuchatel |
|
CH |
|
|
Assignee: |
Philip Morris Products S.A.
Neuchatel
CH
|
Family ID: |
55027621 |
Appl. No.: |
16/066179 |
Filed: |
December 19, 2016 |
PCT Filed: |
December 19, 2016 |
PCT NO: |
PCT/EP2016/081783 |
371 Date: |
June 26, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A24F 47/006 20130101;
A24D 3/043 20130101; A24D 1/025 20130101; A24D 1/02 20130101; A24D
1/027 20130101 |
International
Class: |
A24D 1/02 20060101
A24D001/02; A24F 47/00 20060101 A24F047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 2015 |
EP |
15203245.4 |
Claims
1.-16. (canceled)
17. An aerosol generating article, comprising: a combustible heat
source; an aerosol forming substrate downstream of the combustible
heat source; and a wrapper circumscribing at least a rear portion
of the combustible heat source and at least a front portion of the
aerosol forming substrate, wherein a plurality of weakness
formations are provided on a region of the wrapper overlying the
combustible heat source, and wherein the wrapper is rupturable at
the plurality of weakness formations and is configured to form a
ventilation zone comprising a plurality of apertures extending
through the wrapper.
18. The aerosol generating article according to claim 17, wherein
at least one of the weakness formations is defined by one or more
lines of weakness.
19. The aerosol generating article according to claim 17, wherein
at least one of the weakness formations is defined by two or more
intersecting lines of weakness.
20. The aerosol generating article according to claim 17, wherein
the plurality of weakness formations are formed from a local
reduction in thickness of the wrapper.
21. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a circumferential dimension of at least about 0.5 mm.
22. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a circumferential dimension of from about 0.5 mm to about 2.6
mm.
23. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a circumferential dimension of from about 0.8 mm to about 1.8
mm.
24. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a length of at least about 0.1 mm.
25. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a length of from about 0.1 mm to about 2.1 mm.
26. The aerosol generating article according to claim 17, wherein
each weakness formation of the plurality of weakness formations has
a length of from about 0.2 mm to about 1.8 mm.
27. The aerosol generating article according to claim 17, wherein
adjacent weakness formations among the plurality of weakness
formations are separated in a circumferential direction by a
circumferential separation of at least about 0.5 mm.
28. The aerosol generating article according to claim 17, wherein
adjacent weakness formations among the plurality of weakness
formations are separated in a longitudinal direction by a
longitudinal separation of at least about 0.4 mm.
29. The aerosol generating article according to claim 17, wherein
the plurality of weakness formations are provided in a regular
pattern.
30. The aerosol generating article according to claim 17, wherein
the plurality of weakness formations are arranged such that the
plurality of apertures have a total area of at least about 0.09
millimetres squared.
31. The aerosol generating article according to claim 17, wherein
the weakness formations of the plurality of weakness formations are
arranged such that the plurality of apertures form indicia on an
outer surface of the wrapper.
32. The aerosol generating article according to claim 17, wherein
the wrapper is formed from a heat conductive material.
33. The aerosol generating article according to claim 17, wherein
the wrapper is substantially impermeable to air.
34. The aerosol generating article according to claim 17, wherein
the wrapper circumscribes the combustible heat source along at
least about 50 percent of a length of the combustible heat
source.
35. The aerosol generating article according to claim 34, wherein
the weakness formations of the plurality of weakness formations are
provided on the wrapper such that a ventilation zone extends along
at least about 50 percent of the length of the combustible heat
source.
36. The aerosol generating article according to claim 17, wherein
the wrapper is in direct contact with an outer surface of the
combustible heat source.
Description
[0001] The present invention relates to an aerosol generating
article, such as a heated smoking article. In particular, examples
of the present invention relate to an aerosol generating article
comprising a combustible heat source, an aerosol-forming substrate
downstream of the combustible heat source and a wrapper
circumscribing at least a rear portion of the combustible heat
source and at least a front portion of the aerosol-forming
substrate.
[0002] A number of smoking articles in which tobacco is heated
rather than combusted have been proposed in the art. An 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 a physically
separate 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.
[0003] It is known to include a heat-conducting element around at
least a rear portion of the combustible heat source and at least a
front portion of the aerosol-forming substrate of the heated
smoking article in order to ensure conductive heat transfer from
the combustible heat source to the aerosol-forming substrate to
obtain an aerosol. 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 heat-conducting
element and the aerosol-forming substrate are circumscribed by an
outer wrapper of paper. In use, the front portion of the
aerosol-forming substrate is heated by conduction through the
abutting rear portion of the combustible heat source and the
heat-conducting element.
[0004] In smoking articles in which tobacco is heated rather than
combusted, the temperature attained in the aerosol-forming
substrate has a significant impact on the ability to generate a
sensorially acceptable aerosol. It is typically desirable to
maintain the temperature of the aerosol-forming substrate within a
certain range in order to optimise the aerosol delivery to a user.
In smoking articles comprising a combustible heat source and an
aerosol-forming substrate located downstream of the combustible
heat source, movement of the combustible heat source relative to
the aerosol-forming substrate during use of the smoking article may
cause the temperature of the aerosol-forming substrate to drop
outside of a desired range, thereby impacting the performance of
the smoking article. If the temperature of the aerosol-forming
substrate drops too low, for instance, it may adversely impact the
consistency and the amount of aerosol delivered to a user.
[0005] A number of ways of retaining combustible heat sources in
position within heated smoking articles have been proposed. For
example, it is known to apply a layer of glue around the
combustible heat source, between the combustible heat source and
the wrapper. However, if the glue is combusted during use, the
combustible heat source may be held in place only by the wrapper.
This may lead to movement of the combustible heat source relative
to the aerosol forming substrate if the holding force applied by
the wrapper is insufficient.
[0006] It has also been proposed to wrap the wrapper tightly around
the combustible heat source, or to extend the wrapper such that it
circumscribes the entire length of the combustible heat source.
However, in both cases, the wrapper may adversely affect combustion
of the heat source by restricting the air supply, which may lead to
a drop in the temperature of the aerosol-forming substrate and an
adverse impact on the consistency and the amount of aerosol
delivered to a user. Additionally, the pressure generated by
combustion gases produced by the combustible heat source may build
up behind a tightly wrapped wrapper. This may lead to the creation
of an air gap between the combustible heat source and the wrapper,
reducing the holding force applied during use by the wrapper and
possibly leading to movement of the combustible heat source
relative to the aerosol forming substrate. Where the wrapper
comprises a heat conducting element, air gaps between the
combustible heat source and the wrapper may adversely affect
conductive heat transfer from the combustible heat source to the
aerosol forming substrate by the heat conducting element and hence
the performance of the smoking article. In some cases, pressure
generated by combustion gases behind a tightly wrapped wrapper may
be sufficient to damage the wrapper or the combustible heat
source.
[0007] It would be desirable to provide an aerosol generating
article in which retention of the combustible heat source is
improved preferably with no or low adverse impact on conductive
heat transfer from the combustible heat source to the
aerosol-forming substrate and hence on the performance of the
aerosol generating article.
[0008] According to a first aspect of the present invention, there
is provided an aerosol generating article comprising: a combustible
heat source; an aerosol forming substrate downstream of the
combustible heat source; a wrapper circumscribing at least a rear
portion of the combustible heat source and at least a front portion
of the aerosol forming substrate; wherein a plurality of weakness
formations are provided on a region of the wrapper overlying the
combustible heat source, and wherein the wrapper is rupturable
during use at the plurality of weakness formations to form a
ventilation zone comprising a plurality of apertures extending
through the wrapper.
[0009] Advantageously, with this arrangement, the wrapper can be
applied tightly around the combustible heat source to hold it in
the correct position while still allowing a sufficient supply of
air to the combustible heat source and allowing combustion gases
generated by the heat source to escape through the plurality of
apertures during use. This ensures that the conductive heat
transfer from the heat source to the aerosol forming substrate, and
consequently the performance of the aerosol generating article, is
maintained. It may also remove the need for glue to be applied
around the combustible heat source, simplifying manufacture. In
some examples, the weakness formations are arranged such that the
wrapper ruptures at the weakness formations for example under the
pressure generated by combustion gases. This advantageously allows
the combustible heat source to be ventilated during use without
undue burden on the user. Additionally, by providing weakness
formations at which the wrapper is rupturable to form a plurality
of apertures, the wrapper forms a barrier prior to rupture, for
example to restrict the amount of moisture absorbed from the
atmosphere by the heat source during transportation and storage. As
moisture may hinder the heating performance of the heat source,
restricting the amount of moisture absorbed by the heat source may
have a positive impact on the performance of the aerosol generating
article.
[0010] As used herein, the term "weakness formations" refers to
structural weaknesses in the wrapper arranged to facilitate tearing
or breakage of the wrapper at predefined positions to form
apertures with predefined shapes and dimensions. The structural
weaknesses may be formed for example through removal or destruction
of some of the material in that portion for example laser ablation
or other method, or through mechanical pressing or rolling without
removing material. The term "weakness formations" includes lines of
weakness, along which the wrapper material has been weakened, and
areas of weakness across which the wrapper material has been
removed.
[0011] As used herein, the terms `upstream` and `front`, and
`downstream` and `rear`, are used to describe the relative
positions of components, or portions of components, of the aerosol
generating article in relation to the direction in which air flows
through the aerosol generating article during use thereof. Aerosol
generating articles according to the invention comprise a proximal
end through which, in use, an aerosol exits the article for
delivery to a user. The proximal end of the aerosol generating
article may also be referred to as the mouth end or the downstream
end. In use, a user draws on the mouth end of the aerosol
generating article. The mouth end is downstream of the distal end.
The combustible heat source is located at or proximate to the
distal end. The distal end of the aerosol generating article may
also be referred to as the upstream end. Components, or portions of
components, of the smoking article may be described as being
upstream or downstream of one another based on their relative
positions between the proximal end of the smoking article and the
distal end of the smoking article. The front of a component, or
portion of a component, of the aerosol generating article is the
portion at the end closest to the upstream end of the aerosol
generating article. The rear of a component, or portion of a
component, of the aerosol generating article is the portion at the
end closest to the downstream end of the aerosol generating
article. The rear portion of the combustible heat source is the
portion of the combustible heat source at the downstream end of the
combustible heat source. The front portion of the aerosol forming
substrate is the portion of the aerosol forming substrate at the
upstream end of the aerosol forming substrate.
[0012] In certain preferred embodiments, at least one of the
weakness formations is defined by one or more lines of weakness.
The plurality of weakness formations may each be defined by one or
more lines of weakness. The weakness formations may be defined by
an area of weakness, for example an area of the wrapper having a
local reduction in thickness. At least one of the weakness
formations may be defined by a single line of weakness extending
along the perimeter, or part of the perimeter, of the desired
aperture shape. In such examples, the line of weakness may have any
suitable shape, for example a straight line, a curved or uneven
line, a closed shape, or any combination thereof. In other
examples, at least one of the weakness formations may be defined by
two or more lines of weakness. The two or more lines of weakness
may extend along the perimeter, or part of the perimeter, of the
desired aperture shape. The two or more lines of weakness may
combine to define the perimeter, or part of the perimeter, of the
desired aperture shape. At least one of the weakness formations may
be defined by a plurality of lines of weakness that diverge from an
unweakened central region.
[0013] Where at least one of the weakness formations is defined by
two or more lines of weakness, the two or more lines of weakness
may have substantially the same dimensions. The dimensions of one
or more of the two or more lines of weakness may be different.
[0014] Where at least one of the weakness formations is defined by
one or more lines of weakness, the one or more lines of weakness
preferably do not extend through the thickness of the wrapper. With
such an arrangement, the wrapper may form a barrier prior to
rupture, even in the regions defined by the weakness formation.
[0015] As used herein, the term "line of weakness" refers to a line
in the wrapper along which the wrapper material has been weakened
to facilitate tearing or breakage of the wrapper along a desired
line.
[0016] In certain preferred embodiments, at least one of the
weakness formations is defined by two or more intersecting lines of
weakness. This may allow a sufficiently large aperture to be
defined by the lines of weakness without significantly impacting on
the strength of the wrapper prior to use of the aerosol generating
article. The plurality of weakness formations may each be defined
by two or more intersecting lines. In such examples, the lines of
weakness may have any suitable shape, for example a straight line,
a curved or uneven line, a closed shape, or any combination
thereof. The two or more intersecting lines may intersect each
other at any suitable position along their respective lengths. This
may depend on the desired shape of aperture to be formed by the
rupture of the wrapper at the weakness formation. Preferably, the
two or more intersecting lines of weakness are arranged such that
the resulting weakness formation has an open shape. That is, the
two or more intersecting lines do not combine to completely enclose
any part of the wrapper. With this arrangement, the ruptured
portions of wrapper may remain connected to the aerosol generating
article after the plurality of apertures have been formed. By this,
the creation of debris can be avoided.
[0017] The plurality of weakness formations may be formed from a
local reduction in thickness of the wrapper. In such embodiments,
the local reduction in thickness may be achieved through removal of
material, such as by laser ablation. The local reduction in
thickness may be achieved through mechanical deformation of the
wrapper, such as by rolling or scoring.
[0018] The weakness formations may be defined by a plurality of
perforations.
[0019] The weakness formations may have any suitable
dimensions.
[0020] In certain embodiments, one or more of the weakness
formations may have a circumferential dimension of at least about
0.5 mm, preferably from about 0.5 mm to about 2.6 mm, more
preferably from about 0.8 mm to about 1.8 mm. Preferably, each of
the weakness formations has a circumferential dimension of at least
about 0.5 mm, preferably from about 0.5 mm to about 2.6 mm, more
preferably from about 0.8 mm to about 1.8 mm.
[0021] In certain embodiments, one or more of the weakness
formations may have a length of at least about 0.1 mm, preferably
from about 0.1 mm to about 2.1 mm, more preferably from about 0.2
mm to about 1.8 mm. Preferably, each weakness formation has a
length of at least about 0.1 mm, preferably from about 0.1 mm to
about 2.1 mm, more preferably from about 0.2 mm to about 1.8
mm.
[0022] Preferably the length of each weakness formation is less
than its circumferential dimension. This may help to improve the
resistance of the wrapper to rupture due to tension in the
circumferential direction of the wrapper in comparison to a
weakness formation having a length which is greater than its
circumferential dimension.
[0023] The weakness formations may be separated in the
circumferential direction by any suitable circumferential
separation. In certain embodiments, adjacent weakness formations
are separated in the circumferential direction by a circumferential
separation of at least about 0.5 mm, preferably from about 0.5 mm
to about 2.5 mm, more preferably from about 0.7 mm to about 1.5
mm.
[0024] The weakness formations may be separated in the longitudinal
direction by any suitable longitudinal separation. In certain
embodiments, adjacent weakness formations are separated in the
longitudinal direction by a longitudinal separation of at least
about 0.4 mm, preferably from about 0.4 mm to about 1.8 mm, more
preferably from about 0.5 mm to about 1.3 mm.
[0025] As used herein, the terms "circumferential separation" and
"longitudinal separation" are used to denote the minimum distance
between two adjacent weakness formations in the circumferential
direction and in the longitudinal direction, respectively.
[0026] The plurality of weakness formations may be arranged in an
irregular manner. In certain preferred embodiments, the plurality
of weakness formations are provided in a regular pattern. With this
arrangement, when the wrapper is ruptured along the plurality of
weakness formations, the resulting plurality of apertures are
arranged in a regular pattern. This advantageously may lead to
homogeneous venting of the combustible heat source. Homogeneous
venting of the combustible heat source may prevent sharp localised
increases in gas pressure. It may also prevent sharp localised
increases in heat source temperature.
[0027] As used herein, the term "regular pattern" is used to denote
a pattern comprising a consistently spaced array of weakness
formations. For example, the weakness formations may be provided on
the wrapper in a regular striped pattern, a regular checked or
square pattern, a regular brick pattern, a regular dotted or
spotted pattern, a regular honeycomb or hexagonal pattern or any
other regular alphanumeric, pictographic or geometric pattern.
[0028] In certain preferred embodiments, the plurality of weakness
formations are arranged such that the plurality of apertures have a
total area of at least about 0.09 millimetres squared, preferably
from about 0.09 millimetres squared to about 40 millimetres
squared, more preferably from about 0.4 millimetres squared to
about 30 millimetres squared. This arrangement has been found to
provide sufficient venting of the combustible heat source without
having a significant impact on the strength of the wrapper.
[0029] In certain embodiments, the weakness formations may be
arranged such that the plurality of apertures form visible indicia
on an outer surface of the wrapper. As used herein, the term
"visible indicia" refers to a discrete element, or repeating
elements or patterns that provide an aesthetically pleasing, or
informative, representation. The indicia may be in the form of
text, images, letters, words, logos, or a combination thereof. The
indicia may comprise a brand or manufacturer logo that allows the
consumer to identify the type or origin of the aerosol-generating
article. The indicia may provide information to the user, for
example informing the user that the aerosol generating article is
ready for use. Light emitted from the combustible heat source
during use may be visible through the plurality of apertures. This
may increase the visibility of the indicia.
[0030] The wrapper may comprise any suitable material. In certain
embodiments, the wrapper may comprise a heat conductive material.
The wrapper may be formed from a heat conductive material. In such
embodiments, the wrapper may form a heat conducting element
extending between the combustible heat source and the aerosol
forming substrate. The heat conducting element improves conductive
heat transfer from the combustible heat source to the aerosol
forming substrate.
[0031] As used herein, the term "heat conductive material" is used
to describe a material having a bulk thermal conductivity of at
least about 10 W per metre Kelvin (W/(m K)) at 23 degrees Celsius
and a relative humidity of 50 percent as measured using the
modified transient plan source (MTPS) method. In preferred
embodiments, the wrapper is formed from a heat conductive material
having a bulk thermal conductivity of at least about 50 W per metre
Kelvin, more preferably at least about 100 W per metre Kelvin, most
preferably at least about 150 W per metre Kelvin.
[0032] The wrapper may be air restricting prior to rupture of the
weakness formations. In other words, the wrapper may inhibit or
resist the passage of air through the wrapper prior to use.
[0033] In certain preferred embodiments, the wrapper is
substantially impermeable to air. That is, the wrapper is formed
from one or more materials that are substantially impermeable to
air. With such an arrangement, the wrapper forms a substantially
airtight barrier around the combustible heat source. This may
substantially prevent absorption of moisture from the atmosphere by
the combustible heat source through the wrapper.
[0034] The wrapper circumscribes at least a rear portion of the
combustible heat source. Preferably, the wrapper circumscribes the
combustible heat source along at least about 50 percent of the
length of the combustible heat source. For example, the wrapper may
circumscribe the combustible heat source along at least about 60
percent of the length of the combustible heat source, at least
about 70 percent of the length of the combustible heat source, at
least about 80 percent of the length of the combustible heat
source, or at least about 90 percent of the length of the
combustible heat source. By extending along a greater amount of the
length of the combustible heat source, the wrapper may mechanically
protect the combustible heat source and may retain the combustible
heat source in position relative to the aerosol forming substrate.
Due to the presence of the weakness formations at which the wrapper
is rupturable during use to form a ventilation zone comprising a
plurality of apertures extending through the wrapper, the wrapper
can extend further along the length of the combustible heat source
than might otherwise be possible without adversely effecting the
performance of the aerosol generating article.
[0035] Where the wrapper circumscribes the combustible heat source
along at least about 50 percent of the length of the combustible
heat source, the ventilation zone may extend along less than 50
percent of the length of the combustible heat source. In preferred
embodiments in which the wrapper circumscribes the combustible heat
source along at least about 50 percent of the length of the
combustible heat source, the weakness formations are provided on
the wrapper such that the ventilation zone also extends along at
least about 50 percent of the length of the combustible heat
source.
[0036] In any of the above embodiments, the weakness formations may
be provided on the wrapper such that the ventilation zone extends
along substantially the entire length of the region of the wrapper
overlying the combustible heat source.
[0037] The wrapper may be in indirect contact with an outer surface
of the combustible heat source via one or more intermediate
components. The wrapper may be in direct contact with an outer
surface of the combustible heat source. The wrapper may be in
direct contact with the outer surface of the combustible heat
source along substantially the entire length of the region of the
wrapper overlying the combustible heat source.
[0038] As used herein, the terms `longitudinal` and `axial` are
used to describe the direction between the opposed upstream and
downstream ends of the aerosol generating article, or of a
component of the aerosol generating article.
[0039] As used herein, the term `length` is used to describe the
maximum dimension in the longitudinal direction of a component of
the aerosol generating article, such as the combustible heat
source, or of the aerosol generating article itself. That is, the
maximum dimension in the direction between the opposed upstream and
downstream ends of the component, or of the aerosol generating
article itself.
[0040] As used herein, the terms `radial` and `transverse` are used
to describe the direction perpendicular to the longitudinal
direction. That is, the direction perpendicular to the direction
between the opposed upstream and downstream ends of a component of
the aerosol generating article, such as the combustible heat
source, or of the aerosol generating article itself.
[0041] As used herein, the terms "inner surface" and "outer
surface" refer to the radially inner and radially outer surfaces,
respectively, of a component of the aerosol generating article.
[0042] As used herein, the term `diameter` denotes the maximum
dimension in the transverse direction of a component of the aerosol
generating article, such as the combustible heat source, or of the
aerosol generating article itself.
[0043] Aerosol generating articles according to the present
invention comprise a combustible heat source for heating the
aerosol forming substrate. The combustible heat source is
preferably a solid heat source, and may comprise any suitable
combustible fuel including, but not limited to, carbon and
carbon-based materials containing aluminium, magnesium, one or more
carbides, one or more nitrides and combinations thereof. Solid
combustible heat sources for heated smoking articles and methods
for producing such heat sources are known in the art and described
in, for example, U.S. Pat. No. 5,040,552 and U.S. Pat. No.
5,595,577. Typically, known solid combustible heat sources for
heated smoking articles are carbon-based, that is they comprise
carbon as a primary combustible material.
[0044] The combustible heat source may be a combustible
carbonaceous heat source.
[0045] The combustible heat source is preferably a blind
combustible heat source.
[0046] As used herein, the term `blind` describes a heat source
that does not comprise any airflow channels extending from the
front end face to the rear end face of the combustible heat source.
As used herein, the term `blind` is also used to describe a
combustible heat source including one or more airflow channels
extending from the front end face of the combustible heat source to
the rear end face of the combustible heat source, wherein a
combustible substantially air impermeable barrier between the rear
end face of the combustible heat source and the aerosol-forming
substrate barrier prevents air from being drawn along the length of
the combustible heat source through the one or more airflow
channels.
[0047] The inclusion of one or more closed air passageways
increases the surface area of the blind combustible heat source
that is exposed to oxygen from the air and may advantageously
facilitate ignition and sustained combustion of the blind
combustible heat source.
[0048] Aerosol generating articles according to the invention
comprising blind combustible heat sources comprise one or more air
inlets downstream of the rear end face of the combustible heat
source for drawing air into one or more airflow pathways through
the aerosol generating article. Aerosol generating articles
according to the invention comprising non-blind combustible heat
sources may also comprise one or more air inlets downstream of the
rear end face of the combustible heat source for drawing air into
one or more airflow pathways through the aerosol generating
article.
[0049] In some embodiments, aerosol generating articles according
to the invention comprising blind combustible heat sources comprise
one or more air inlets located proximate to the downstream end of
the aerosol-forming substrate.
[0050] In use, air drawn along the one or more airflow pathways of
aerosol generating articles according to the invention comprising a
blind combustible heat source does not pass through any airflow
channels along the blind combustible heat source. The lack of any
airflow channels through the blind combustible heat source
advantageously substantially prevents or inhibits activation of
combustion of the blind combustible heat source during puffing by a
user. This substantially prevents or inhibits spikes in the
temperature of the aerosol-forming substrate during puffing by a
user. By preventing or inhibiting activation of combustion of the
blind combustible heat source, and so preventing or inhibiting
excess temperature increases in the aerosol-forming substrate,
combustion or pyrolysis of the aerosol-forming substrate under
intense puffing regimes may be advantageously avoided. In addition,
the impact of a user's puffing regime on the composition of the
mainstream aerosol may be advantageously minimised or reduced.
[0051] The inclusion of a blind combustible heat source may also
advantageously substantially prevent or inhibit combustion and
decomposition products and other materials formed during ignition
and combustion of the blind combustible heat source from entering
air drawn through aerosol generating articles according to the
invention during use thereof. This is particularly advantageous
where the blind combustible heat source comprises one or more
additives to aid ignition or combustion of the blind combustible
heat source.
[0052] In aerosol generating articles according to the invention
comprising a blind combustible heat source, heat transfer from the
blind combustible heat source to the aerosol-forming substrate
occurs primarily by conduction. Heating of the aerosol-forming
substrate by forced convection is minimised or reduced. This may
advantageously help to minimise or reduce the impact of a user's
puffing regime on the composition of the mainstream aerosol of
articles according to the invention.
[0053] In aerosol generating articles according to the invention
comprising a blind combustible heat source, it is particularly
important to optimise the conductive heat transfer between the
combustible heat source and the aerosol-forming substrate. As
described further below, the inclusion of one or more
heat-conducting elements around at least a rear portion of the
combustible carbonaceous heat source and at least a front portion
of the aerosol-forming substrate is particularly preferred in
aerosol generating articles according to the invention including
blind heat sources, where there is little if any heating of the
aerosol-forming substrate by forced convection.
[0054] In certain embodiments of the invention, the combustible
heat source comprises at least one longitudinal airflow channel,
which provides one or more airflow pathways through the heat
source. The term "airflow channel" is used herein to describe a
channel extending along the length of the heat source through which
air may be drawn through the aerosol generating article. Such heat
sources including one or more longitudinal airflow channels are
referred to herein as "non-blind" heat sources.
[0055] The diameter of the at least one longitudinal airflow
channel may be between about 1.5 mm and about 3 mm, more preferably
between about 2 mm and about 2.5 mm. The inner surface of the at
least one longitudinal airflow channel may be partially or entirely
coated, as described in more detail in WO-A-2009/022232.
[0056] 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 aerosol generating 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.
[0057] The aerosol-forming substrate may be a solid aerosol-forming
substrate. Alternatively, the aerosol-forming substrate may
comprise both solid and liquid components. The aerosol-forming
substrate may comprise a tobacco-containing material containing
volatile tobacco flavour compounds, which are released from the
substrate upon heating. Alternatively, the aerosol-forming
substrate may comprise a non-tobacco material. The aerosol-forming
substrate may further comprise one or more aerosol formers.
Examples of suitable aerosol formers include, but are not limited
to, glycerine and propylene glycol.
[0058] The aerosol-forming substrate may be a rod comprising a
tobacco-containing material.
[0059] If the aerosol-forming substrate is a solid aerosol-forming
substrate, the solid aerosol-forming substrate may comprise, for
example, one or more of: powder, granules, pellets, shreds,
spaghetti strands, strips or sheets containing one or more of: herb
leaf, tobacco leaf, fragments of tobacco ribs, reconstituted
tobacco, homogenised tobacco, extruded tobacco and expanded
tobacco. The solid aerosol-forming substrate may be in loose form,
or may be provided in a suitable container or cartridge. For
example, the aerosol-forming material of the solid aerosol-forming
substrate may be contained within a paper or other wrapper and have
the form of a plug. Where an aerosol-forming substrate is in the
form of a plug, the entire plug including any wrapper is considered
to be the aerosol-forming substrate.
[0060] Optionally, the solid aerosol-forming substrate may contain
additional tobacco or non-tobacco volatile flavour compounds, to be
released upon heating of the solid aerosol-forming substrate. The
solid aerosol-forming substrate may also contain capsules that, for
example, include the additional tobacco or non-tobacco volatile
flavour compounds and such capsules may melt during heating of the
solid aerosol-forming substrate.
[0061] Optionally, the solid aerosol-forming substrate may be
provided on or embedded in a thermally stable carrier. The carrier
may take the form of powder, granules, pellets, shreds, spaghetti
strands, strips or sheets. The solid aerosol-forming substrate may
be deposited on the surface of the carrier in the form of, for
example, a sheet, foam, gel or slurry. The solid aerosol-forming
substrate may be deposited on the entire surface of the carrier, or
alternatively, may be deposited in a pattern in order to provide a
non-uniform flavour delivery during use.
[0062] The aerosol-forming substrate may be in the form of a plug
or segment comprising a material capable of emitting volatile
compounds in response to heating circumscribed by a paper or other
wrapper. Where an aerosol-forming substrate is in the form of such
a plug or segment, the entire plug or segment including any wrapper
is considered to be the aerosol-forming substrate.
[0063] The aerosol-forming substrate preferably has a length of
between about 5 mm and about 20 mm. In certain embodiments, the
aerosol-forming substrate may have a length of between about 6 mm
and about 15 mm or a length of between about 7 mm and about 12
mm.
[0064] The aerosol-forming substrate may comprise a plug of
tobacco-based material wrapped in a plug wrap. In preferred
embodiments, the aerosol-forming substrate comprises a plug of
homogenised tobacco-based material wrapped in a plug wrap.
[0065] In any of the above embodiments, the combustible heat source
and the aerosol-forming substrate may be in abutting coaxial
alignment. As used herein, the terms "abutting" and "abut" are used
to describe a component, or a portion of a component, being in
direct contact with another component, or portion of a component.
This includes embodiments in which the combustible heat source
comprises a non-combustible barrier between its rear face and the
aerosol forming substrate, the non-combustible barrier being in
direct contact with the aerosol forming substrate.
[0066] Aerosol generating articles according to the invention may
comprise a heat-conducting element around and in direct contact
with both at least a rear portion of the combustible heat source
and at least a front portion of the aerosol-forming substrate. In
such embodiments, the heat-conducting element provides a thermal
link between the combustible heat source and the aerosol-forming
substrate of aerosol generating articles according to the invention
and advantageously helps to facilitate adequate heat transfer from
the combustible heat source to the aerosol-forming substrate to
provide an acceptable aerosol.
[0067] Aerosol generating articles according to the invention may
comprise a heat-conducting element spaced apart from one or both of
the combustible heat source and the aerosol-forming substrate, such
that there is no direct contact between the heat-conducting element
and one or both of the combustible heat source and the
aerosol-forming substrate.
[0068] Where the aerosol generating article comprises a
heat-conducting element around at least a rear portion of the
combustible heat source and at least a front portion of the
aerosol-forming substrate, the heat-conducting element may be
formed by the wrapper. For example, the wrapper may comprise one or
more layers of heat conductive material which form the one or more
heat-conducting elements.
[0069] The heat-conducting element is preferably non-combustible.
In certain embodiments, the heat-conducting element may be oxygen
restricting. In other words, the one or more heat-conducting
elements may inhibit or resist the passage of oxygen through the
heat-conducting element.
[0070] Suitable heat-conducting elements include, but are not
limited to: metal foil wrappers such as, for example, aluminium
foil wrappers, steel wrappers, iron foil wrappers and copper foil
wrappers; and metal alloy foil wrappers.
[0071] Aerosol generating articles according to the invention may
comprise a transfer element, or spacer element, downstream of the
aerosol-forming substrate. Such an element may take the form of a
hollow tube that is located downstream of an aerosol-forming
substrate.
[0072] The transfer element may abut one or both of the
aerosol-forming substrate and a mouthpiece. Alternatively, the
transfer element may be spaced apart from one or both of the
aerosol-forming substrate and the mouthpiece.
[0073] The inclusion of a transfer element advantageously allows
cooling of the aerosol generated by heat transfer from the
combustible heat source to the aerosol forming substrate. The
inclusion of a transfer element also advantageously allows the
overall length of the aerosol generating article to be adjusted to
a desired value, for example to a length similar to that of a
conventional cigarette, through an appropriate choice of the length
of the transfer element.
[0074] The transfer element may have a length of between about 7 mm
and about 50 mm, for example a length of between about 10 mm and
about 45 mm or of between about 15 mm and about 30 mm. The transfer
element may have other lengths depending upon the desired overall
length of the aerosol generating article, and the presence and
length of other components within the aerosol generating
article.
[0075] Preferably, the transfer element comprises at least one
open-ended tubular hollow body. In such embodiments, in use, air
drawn into the aerosol generating article passes through the at
least one open-ended tubular hollow body as it passes downstream
through the aerosol generating article from the aerosol-forming
substrate to the distal end of the aerosol generating article.
[0076] The transfer element may comprise at least one open-ended
tubular hollow body formed from one or more suitable materials that
are substantially thermally stable at the temperature of the
aerosol generated by the transfer of heat from the combustible heat
source to the aerosol-forming substrate. Suitable materials are
known in the art and include, but are not limited to, paper,
cardboard, plastics, such a cellulose acetate, ceramics and
combinations thereof.
[0077] Aerosol generating articles according to the invention may
comprise an aerosol-cooling element or heat exchanger downstream of
the aerosol-forming substrate. The aerosol-cooling element may
comprise a plurality of longitudinally extending channels. Where
the aerosol generating article comprises a transfer element
downstream of the aerosol-forming substrate, the aerosol-cooling
element is preferably downstream of the transfer element.
[0078] The aerosol-cooling element may comprise a gathered sheet of
material selected from the group consisting of metallic foil,
polymeric material, and substantially non-porous paper or
cardboard. In certain embodiments, the aerosol-cooling element may
comprise a gathered sheet of material selected from the group
consisting of polyethylene (PE), polypropylene (PP),
polyvinylchloride (PVC), polyethylene terephthalate (PET),
polylactic acid (PLA), cellulose acetate (CA), and aluminium
foil.
[0079] In certain preferred embodiments, the aerosol-cooling
element may comprise a gathered sheet of biodegradable polymeric
material, such as polylactic acid (PLA) or a grade of Mater-Bi.RTM.
(a commercially available family of starch based copolyesters).
[0080] Preferably, the aerosol generating article comprises a
mouthpiece downstream of the aerosol-forming substrate and
positioned at the downstream end of the aerosol generating article.
The mouthpiece may comprise a filter. For example, the mouthpiece
may comprise a filter plug having one or more segments. Where the
mouthpiece comprises a filter plug, preferably the filter plug is a
single segment filter plug. The filter plug may comprise one or
more segments comprising cellulose acetate, paper or other suitable
known filtration materials, or combinations thereof. Preferably,
the filter plug comprises filtration material of low filtration
efficiency.
[0081] Aerosol-generating articles according to the present
invention may comprise a plurality of elements assembled in the
form of a rod.
[0082] As used herein, the term `aerosol-generating article` is
used to denote an article comprising an aerosol-forming substrate
that is capable of releasing volatile compounds that can form an
aerosol. An aerosol-generating article may be a non-combustible
aerosol-generating article, which is an article that releases
volatile compounds without the combustion of the aerosol-forming
substrate. An aerosol-generating article may be a heated
aerosol-generating article, which is an aerosol-generating article
comprising an aerosol-forming substrate that is intended to be
heated rather than combusted in order to release volatile compounds
that can form an aerosol. A heated aerosol-generating article may
comprise an onboard heating means forming part of the
aerosol-generating article, or may be configured to interact with
an external heater forming part of a separate aerosol-generating
device.
[0083] An aerosol-generating article may be a smoking article. An
aerosol-generating article may be a smoking article that generates
an aerosol that is directly inhalable into a user's lungs through
the user's mouth. An aerosol-generating article may resemble a
conventional smoking article, such as a cigarette. An
aerosol-generating article may comprise tobacco. An
aerosol-generating article may be disposable. An aerosol-generating
article may be partially-reusable and comprise a replenishable or
replaceable aerosol-forming substrate.
[0084] The aerosol generating article may be substantially
cylindrical in shape. The aerosol generating article may be
substantially elongate. The aerosol-forming substrate may be
substantially cylindrical in shape. The aerosol-forming substrate
may be substantially elongate. The aerosol-forming substrate may be
located in the aerosol generating article such that the length of
the aerosol-forming substrate is substantially parallel to the
airflow direction in the aerosol generating article.
[0085] The transfer section or element may be substantially
elongate.
[0086] The aerosol generating article may have any desired length.
For example, the aerosol generating article may have a total length
of between approximately 65 mm and approximately 100 mm. The
aerosol generating article may have any desired external diameter.
For example, the aerosol generating article may have an external
diameter of between approximately 5 mm and approximately 12 mm.
[0087] The aerosol generating article may be circumscribed by an
outer wrapper of, for example, cigarette paper, which has low air
permeability. Alternatively or in addition, the mouthpiece may be
circumscribed by tipping paper.
[0088] It should also be appreciated that particular combinations
of the various features described and defined in any aspects of the
invention can be implemented and/or supplied and/or used
independently.
[0089] The invention will be further described, by way of example
only, with reference to the accompanying drawings in which:
[0090] FIG. 1 shows a schematic longitudinal cross-sectional view
of a first embodiment of smoking article according to the present
invention;
[0091] FIGS. 2A and 2B show a schematic side perspective view of a
multi-segment component of the smoking article of FIG. 1 having a
wrapper with a plurality of weakness formations according to a
first example;
[0092] FIG. 2C shows an enlarged view of the wrapper of the
multi-segment component of FIGS. 2A and 2B;
[0093] FIG. 3 shows a schematic side perspective view of the
smoking article of FIG. 1, in which the cap has been removed and
the wrapper is ruptured to form a ventilation zone;
[0094] FIG. 4A shows an enlarged view of a wrapper for the smoking
article of FIG. 1, the wrapper having a plurality of weakness
formations according to a second example;
[0095] FIG. 4B shows an enlarged view of the wrapper of FIG. 4A in
which the wrapper is ruptured at the weakness formations to form a
ventilation zone.
[0096] The smoking article 100 according to the first embodiment of
the invention shown in FIG. 1 comprises a combustible heat source
102, an aerosol-forming substrate 104, a transfer element 106, an
aerosol-cooling element 108, a spacer element 110 and a mouthpiece
112 in abutting coaxial alignment. The combustible carbonaceous
heat source 102 has a front end face 114 and an opposed rear end
face 116. As shown in FIG. 1, the combustible heat source 102,
aerosol-forming substrate 104, transfer element 106,
aerosol-cooling element 108, spacer element 110 and mouthpiece 112
are wrapped in an outer wrapper 118 of sheet material such as, for
example, cigarette paper.
[0097] The combustible heat source 102 is a blind carbonaceous
combustible heat source and is located at the distal end of the
smoking article 100. As shown in FIG. 1, a non-combustible
substantially air impermeable barrier 120 in the form of a disc of
aluminium foil is provided between the rear end face 116 of the
combustible carbonaceous heat source 102 and the aerosol-forming
substrate 104. The barrier 120 is applied to the rear end face 116
of the combustible heat source 102 by pressing the disc of
aluminium foil onto the rear end face 116 of the combustible heat
source 102. The barrier 120 and abuts the rear end face 116 of the
combustible carbonaceous heat source 102 and the aerosol-forming
substrate 104.
[0098] The aerosol-forming substrate 104 is located immediately
downstream of the barrier 120 applied to the rear end face 116 of
the combustible carbonaceous heat source 102. As shown in FIG. 1,
the combustible heat source 102 and the aerosol-forming substrate
104 are in abutting coaxial alignment. The aerosol-forming
substrate 104 comprises a cylindrical plug of homogenised
tobacco-based material 122 including an aerosol former such as, for
example, glycerine, wrapped in plug wrap 124.
[0099] The transfer element 106 is located immediately downstream
of the aerosol-forming substrate 104 and comprises a cylindrical
open-ended hollow cellulose acetate tube 128.
[0100] The aerosol-cooling element 108 is located immediately
downstream of the transfer element 106 and comprises a gathered
sheet of biodegradable polymeric material such as, for example,
polylactic acid.
[0101] The spacer element 110 is located immediately downstream of
the aerosol-cooling element 108 and comprises a cylindrical
open-ended hollow paper or cardboard tube.
[0102] The mouthpiece 112 is located immediately downstream of the
spacer element 110. As shown in FIG. 1, the mouthpiece 112 is
located at the proximal end of the smoking article 100 and
comprises a cylindrical plug of suitable filtration material 130
such as, for example, cellulose acetate tow of very low filtration
efficiency, wrapped in filter plug wrap 132. The smoking article
100 may further comprise a band of tipping paper (not shown)
circumscribing a downstream end portion of the outer wrapper
118.
[0103] As shown in FIG. 1, the smoking article 100 further
comprises a wrapper 126 circumscribing at least a rear portion of
the combustible heat source 102 and at least a front portion of the
aerosol forming substrate 104. The wrapper 126 is wrapped tightly
around the combustible heat source 102 and the aerosol forming
substrate 104 to maintain the correct position of the combustible
heat source 102 relative to the aerosol forming substrate. In this
example, the wrapper 126 is formed from a heat conductive material
such as, for example, aluminium foil, such that it forms a heat
conducting element. Thus, the wrapper 126 forms a thermal bridge
between the combustible heat source 102 and the aerosol forming
substrate to ensure sufficient conductive heat transfer from the
combustible heat source 102 to the aerosol forming substrate 104.
The wrapper 126 is substantially impermeable to air. Consequently,
the wrapper 126 forms a barrier prior to rupture, for example to
restrict the amount of moisture absorbed from the atmosphere by the
combustible heat source 102 during transportation and storage. As
moisture may hinder the heating performance of the heat source,
restricting the amount of moisture absorbed by the heat source may
have a positive impact on the performance of the smoking article
100. In other examples, the wrapper 126 may be formed from a heat
insulative sheet material such as, for example, cigarette paper, of
low air permeability, which is wrapped around the combustible heat
source 102 and the aerosol-forming substrate 104.
[0104] In this example, the wrapper 126 overlies the entire length
of the combustible heat source 102, with the exception of a front
portion adjacent to the front end face 114 of the combustible heat
source 102, and the entire length of the aerosol-forming substrate
104. In other embodiments of the invention (not shown), the
aerosol-forming substrate 104 may extend beyond the heat-conducting
element 126 in the downstream direction. That is the wrapper 126
may overlie only a front portion of the aerosol-forming substrate
104. It will be appreciated that in other embodiments of the
invention (not shown), one or more additional heat-conducting
elements may be provided that overlie the wrapper 126.
[0105] In this example, the smoking article 100 further comprises a
removable cap 134 at its distal end and directly adjacent to the
heat source 102. For example, the removable cap may comprise a
central portion including a desiccant, such as glycerine, to absorb
moisture as compared to the heat source, which is wrapped in a
portion of the outer wrapper 118 and connected to the rest of the
outer wrapper 118 along a line of weakness 136 comprising a
plurality of perforations in the outer wrapper that circumscribe
the smoking article. To use the smoking article, the user removes
the removable cap 134 by transversely compressing the cap by
pinching it between thumb and finger. By compressing the cap,
sufficient force is provided to the line of weakness 136 to locally
break the outer wrapper 118. The user then removes the cap by
twisting the cap to break the remaining portion of the line of
weakness. When the cap is removed, the front portion of the
combustible heat source 102 is exposed which enables the user to
light the smoking article 100.
[0106] The smoking article 100 comprises one or more air inlets 138
around the periphery of the aerosol-forming substrate 104. As shown
in FIG. 1, a circumferential arrangement of air inlets 138 is
provided in the plug wrap 126 of the aerosol-forming substrate 104
and the overlying outer wrapper 120 to admit cool air (shown by
dotted arrows in FIG. 1) into the aerosol-forming substrate
104.
[0107] In use, the user removes the cap 134 and ignites the
combustible heat source 102, which heats the aerosol-forming
substrate 104 to produce an aerosol. When the user inhales on the
mouthpiece 110, air (shown by dotted arrows in FIG. 1) is drawn
into the aerosol-forming substrate 104 through the air inlets
138.
[0108] The front portion of the aerosol-forming substrate 104 is
heated by conduction through the rear end face 116 of the
combustible carbonaceous heat source 102, through the barrier 120
and through the wrapper 126 which acts as a heat conducting
element.
[0109] The heating of the aerosol-forming substrate 104 by
conduction releases glycerine and other volatile and semi-volatile
compounds from the plug of homogenised tobacco-based material 122.
The compounds released from the aerosol-forming substrate 104 form
an aerosol that is entrained in the air drawn into the
aerosol-forming substrate 104 of the smoking article 100 through
the air inlets 138 as it flows through the aerosol-forming
substrate 104. The drawn air and entrained aerosol (shown by dashed
arrows in FIG. 1) pass downstream through the interior of the
cylindrical open-ended hollow cellulose acetate tube 128 of the
transfer element 106, the aerosol-cooling element 108 and the
spacer element 110, where they cool and condense. The cooled drawn
air and entrained aerosol pass downstream through the mouthpiece
112 and are delivered to the user through the proximal end of the
smoking article 100. The non-combustible substantially air
impermeable barrier 120 on the rear end face 116 of the combustible
heat source 102 isolates the combustible heat source 102 from air
drawn through the smoking article 100 such that, in use, air drawn
through the smoking article 100 does not come into direct contact
with the combustible heat source 102.
[0110] FIGS. 2A and 2B show a schematic side perspective view of a
multi-segment component 140 of the smoking article 100 of FIG. 1.
The multi-segment component 140 comprises the combustible heat
source 102, aerosol forming substrate 104 and wrapper 126 of the
smoking article 100 of FIG. 1. FIG. 2A shows the wrapper 126
circumscribing the combustible heat source 102 and the aerosol
forming substrate 104. FIG. 2B shows the wrapper 126 as partially
unravelled to allow the combustible heat source 102 and the
aerosol-forming substrate 104 to be viewed.
[0111] The multi-segment component 140 may be pre-assembled
separately to the remaining components of the smoking article for
subsequent assembly, or may be manufactured and assembled together
with one or more other components of the smoking article 100.
[0112] As shown in FIGS. 2A and 2B, a plurality of weakness
formations 150 according to a first example are provided on a
weakness region 160 of the wrapper 126 overlying the combustible
heat source 102. The wrapper 126 is rupturable at the weakness
formations 150 to form a ventilation zone corresponding to the
weakness region 160. The weakness formations 150 are arranged in a
regular pattern of aligned rows and columns on the wrapper 126 and
do not extend through the thickness of the wrapper.
[0113] FIG. 2C shows an enlarged view of the wrapper 126 of the
multi-segment component 140. In this example, the weakness
formations 150 are each defined by a plurality of lines of weakness
152 extending from a central unweakened region 154. The lines of
weakness 152 are oblique to the longitudinal direction of the
multi-segment component 140. In this example, each weakness
formation 150 is shown as including lines of weakness 152, the four
lines being grouped into two pairs of collinear lines that are
transverse to each other such that each weakness formation 150 is
approximately `X` shaped. As the lines are of similar length, the
weakness formations 150 will form approximately square shaped
apertures upon rupture.
[0114] Although each weakness formation 150 is shown as being
defined by four lines of weakness 152, it will be appreciated that
one or more of the weakness formations may be formed from fewer or
more than four lines of weakness. For example, one or more of the
weakness formations may be formed from three or more lines of
weakness extending from a central unweakened region. In other
examples, one or more of the weakness formations may comprise two
or more intersecting lines of weakness. In such examples, the lines
of weakness may intersect towards either end of one or more of the
lines of weakness. The intersecting lines of weakness may intersect
at a central region of the weakness formation. In yet further
examples, one or more weakness formations may be formed by one or
more lines of weakness extending along the perimeter, or part of
the perimeter, of the desired aperture shape.
[0115] Although the lines of weakness 152 are shown as being of
similar length, in other examples, one or more of the lines of
weakness may be of different length.
[0116] Adjacent weakness formations are separated in the
circumferential direction by a circumferential separation 156 and
in the longitudinal direction by a longitudinal separation 157.
Preferably, the circumferential separation 156 is at least about
0.5 mm, preferably from about 0.5 mm to about 2.5 mm, more
preferably from about 0.7 mm to about 1.5 mm. Preferably, the
longitudinal separation 157 is at least about 0.4 mm, preferably
from about 0.4 mm to about 1.8 mm, more preferably from about 0.5
mm to about 1.3 mm.
[0117] Each weakness formation has a circumferential dimension 158
and a length 159. Preferably, the circumferential dimension 158 is
at least about 0.5 mm, preferably from about 0.5 mm to about 2.6
mm, more preferably from about 0.8 mm to about 1.8 mm. Preferably,
the length 159 is at least about 0.1 mm, preferably from about 0.1
mm to about 2.1 mm, more preferably from about 0.2 mm to about 1.8
mm.
[0118] The weakness formations 150 are arranged so that the
resulting plurality of apertures has a total aperture area which is
sufficient to allow sufficient supply of air to the combustible
heat source 102 and to allow sufficient venting of combustion gases
from the combustible heat source 102. Preferably, the weakness
formations 150 are arranged so that the resulting plurality of
apertures has a total aperture area of at least about 0.09
millimetres squared, preferably from about 0.09 millimetres squared
to about 40 millimetres squared, more preferably from about 0.4
millimetres squared to about 30 millimetres squared.
[0119] During use of the smoking article 100, pressure exerted on
the wrapper 126 by combustion gases released by the combustible
heat source 102 causes the wrapper 126 to rupture at the weakness
formations 150 to form a ventilation zone comprising a plurality of
apertures extending through the wrapper 126, as discussed below in
relation to FIG. 3.
[0120] FIG. 3 shows a schematic side view of the smoking article
100 during use. As shown, the cap has been removed from the
upstream end of the smoking article to allow the combustible heat
source 102 to be lit by the user at its upstream end. When lit, the
combustible heat source 102 generates heat and combustion gases
which exert pressure on the wrapper 126. This causes the wrapper
126 to rupture at the weakness formations to form a ventilation
zone 180 comprising a plurality of apertures 170 extending through
the wrapper 126, with each aperture 170 corresponding to a weakness
formation in the wrapper.
[0121] Due to the presence of the ventilation zone 180, the supply
of air to the combustible heat source may be sufficient despite
tight wrapping of the wrapper 126 around the combustible heat
source 102. This ensures that there is no significant adverse
effect on the amount of heat generated by the combustible heat
source 102 during use, despite the extent to which the combustible
heat source 102 is covered by the wrapper 126. The ventilation zone
180 also allows combustion gases generated by the combustible heat
source 102 to escape through the plurality of apertures 170. This
prevents a build up of excessive pressure behind the wrapper 126
which may, given the amount of the combustible heat source 102
which is covered by the wrapper 126, lead to a radial gap being
formed between the wrapper 126 and the combustible heat source 102,
which could in turn lead to relative movement between the
combustible heat source 102 and the aerosol forming substrate 104.
The ventilation zone 180 thus ensures that the heat generation by
the combustible heat source 102, the conductive heat transfer from
the heat source 102 to the aerosol forming substrate 104, and
consequently the performance of the smoking article, is maintained,
despite the extent to which the combustible heat source 102 is
covered by the wrapper 126.
[0122] As shown in FIG. 3, the combustible heat source 102 has a
diameter 190 and extends upstream of the upstream end of the
wrapper 126 by an amount 192. The wrapper 126 extends upstream of
the outer wrapper 118 by an amount 194 and is overlapped at its
downstream by the outer wrapper 118 by an amount 196. Example
ranges for dimensions 190, 192, 194 and 196 are shown below in
Table 1.
TABLE-US-00001 EXAMPLE PREFERRED DIMENSION DIMENSION RANGE
DIMENSION RANGE 190 5-12 mm 7-8.1 mm 192 0-4 mm 1-2 mm 194 4-11 mm
5-8 mm 196 1-5 mm 2-4 mm
[0123] FIG. 4A shows an enlarged view of an alternative wrapper 426
for the smoking article 100 of FIG. 1, the wrapper 426 having a
plurality of weakness formations according to a second example. As
shown in FIG. 4A, each weakness formation 450 comprises a
circumferential line of weakness 452 and a longitudinal line of
weakness 453 intersecting at a central region 454. The weakness
formations 450 are arranged in a regular pattern of evenly spaced
rows, with adjacent rows being longitudinally offset and alternate
rows being longitudinally aligned. It will be appreciated that
other patterns of weakness formation are also envisaged.
[0124] Adjacent weakness formations 450 in longitudinally aligned
alternate rows are separated in the circumferential direction by a
circumferential separation 456. Adjacent weakness formations 450 in
each row are separated in the longitudinal direction by a
longitudinal separation 457. Preferably, the circumferential
separation 456 is at least about 0.5 mm, preferably from about 0.5
mm to about 2.5 mm, more preferably from about 0.7 mm to about 1.5
mm. Preferably, the longitudinal separation 457 is at least about
0.4 mm, preferably from about 0.4 mm to about 1.8 mm, more
preferably from about 0.5 mm to about 1.3 mm
[0125] Each weakness formation 450 has a circumferential dimension
458 and a length 459. As the weakness formations 450 are each
formed by a circumferential line of weakness 452 and a longitudinal
line of weakness 453, the circumferential dimension 458 corresponds
to the circumferential length of the circumferential line of
weakness 452 and the longitudinal dimension 459 corresponds to the
length of the longitudinal line of weakness 453. Preferably, the
circumferential dimension 458 is at least about 0.5 mm, preferably
from about 0.5 mm to about 2.6 mm, more preferably from about 0.8
mm to about 1.8 mm. Preferably, the length 459 is at least about
0.1 mm, preferably from about 0.1 mm to about 2.1 mm, more
preferably from about 0.2 mm to about 1.8 mm.
[0126] FIG. 4B shows an enlarged view of the wrapper 426 of FIG. 4A
in which the wrapper 426 has ruptured at the plurality of weakness
formations to form a ventilation zone 480 comprising a plurality of
apertures 470 through the wrapper 426. As shown, due to the
arrangement of the weakness formations, the plurality of apertures
470 are approximately diamond shaped and the ruptured portions 472
of wrapper have remained attached to the wrapper 426. This avoids
the creation of debris from the wrapper 426.
[0127] The specific embodiments and examples described above
illustrate but do not limit the invention. It is to be understood
that other embodiments of the invention may be made and the
specific embodiments and examples described herein are not
exhaustive.
* * * * *