[0001] The present invention relates to an aerosol-forming substrate. In particular, the
present invention relates to an aerosol-forming substrate for use in an aerosol generating
system, the aerosol-forming substrate comprising a first particulate material and
a second particulate material, and a process for manufacturing such an aerosol-forming
substrate.
[0002] Aerosol generating systems for delivering an aerosol to a user typically comprise
an atomiser configured to generate an inhalable aerosol from an aerosol-forming substrate.
Some known aerosol generating systems comprise a thermal atomiser such as an electric
heater or an inductive heating device. The thermal atomiser is configured to heat
and vaporise the aerosol-forming substrate to generate an aerosol. Typical aerosol-forming
substrates for use in aerosol generating systems are nicotine formulations, which
may be liquid nicotine formulations comprising an aerosol former such as glycerine
and propylene glycol. Alternatively, aerosol-forming substrates for use in aerosol
generating systems may comprise solid components. For example, aerosol-forming substrates
may comprise particulate material having a certain size.
[0003] WO2018122095 A1 relates to a sheet comprising: cellulosic material comprising cellulose powder, wherein
the weight ratio of cellulose powder to total cellulosic material in the sheet on
a dry weight basis is greater than about 1:2; and one or more nicotine salts, wherein
at least about 20% by weight of the one or more nicotine salts are monoprotic.
[0004] WO2021094160 A1 relates to a tobacco flavoured dry powder formulation comprising a plurality of particles
comprising a base material and a tobacco flavouring composition, wherein a first ratio
by weight of (β-ionone + β-damascenone) to (phenol) in the tobacco flavoured dry powder
formulation is greater than 0.25. There is provided a method of producing one such
tobacco flavoured powder formulation comprising the steps of: preparing a tobacco
starting material; heating the tobacco starting material at an extraction temperature
of between 100 degrees Celsius and 160 degrees Celsius for at least 90 minutes; collecting
the volatile compounds released from the tobacco starting material during the heating
step; forming a liquid tobacco flavouring composition comprising the collected volatile
compounds; combining a base material and the liquid tobacco flavouring composition
to form tobacco flavoured particles.
[0005] WO2019/003118 A1 relates to a container containing a powder system including a first plurality of
particles having a particle size of about 10 micrometers or less, and a second plurality
of particles having a particle size of about 20 micrometers or greater, and a single
aperture extending through the container.
[0006] WO2005/104712 A2 relates to an inhalable dry powder formulation containing SAE-CD and an active agent
is provided. The average particle size of the SAE-CD is large enough to preclude (for
the most part) pulmonary deposition thereof.
[0007] However, it has been found that solid aerosol-forming substrates comprising particulate
material may be difficult to handle during manufacturing due to agglomerations of
the particulate material. In addition, aerosol-forming substrates comprising solid
particulate formed into sheets may exhibit defects such as stretch marks and slits.
It has also been found that such aerosol-forming substrates may not provide delivery
of aerosol for the whole duration of the user experience of the aerosol-forming substrate.
[0008] It would be desirable to provide an aerosol-forming substrate which is straightforward
to handle during manufacturing and which does not exhibit the defects observed in
the prior art. It would also be desirable to provide an aerosol-forming substrate
which provides acceptable delivery of an aerosol over the whole duration of the user
experience of the aerosol-forming substrate.
[0009] The present disclosure relates to an aerosol-forming substrate for use in an aerosol
generating system. The aerosol-forming substrate may be a solid unitary body. The
aerosol-forming substrate may comprise a first particulate material. The aerosol-forming
substrate may comprise a second particulate material. The first particulate material
may be formed from particles having a D50 size of between 2 micrometres and 20 micrometres.
The second particulate material may be formed from particles having a D50 size of
between 50 micrometres and 80 micrometres.
[0010] According to the present invention, there is provided an aerosol-forming substrate
for use in an aerosol generating system. The substrate comprising a first particulate
material, a second particulate material, the first particulate material being formed
from particles having a D50 size of between 2 micrometres and 20 micrometres, and
the second particulate material being formed from particles having a D50 size of between
50 micrometres and 80 micrometres.
[0011] According to the present invention, there is provided an aerosol-forming substrate
for use in an aerosol generating system wherein the aerosol-forming substrate is a
solid unitary body and comprises: a first particulate material, and a second particulate
material, the first particulate material being formed from particles having a D50
size of between 2 micrometres and 20 micrometres, and the second particulate material
being formed from particles having a D50 size of between 50 micrometres and 80 micrometres.
[0012] As used herein with reference to the present invention, the term "solid unitary body"
refers to an aerosol-forming substrate comprising the first particulate material and
the second particulate material held together in a single solid agglomeration.
[0013] According to the present invention, there is also provided a process for manufacturing
an aerosol-forming substrate, the process comprising: providing a first particulate
material, the first particulate material being formed from particles having a D50
size of between 2 micrometres and 20 micrometres; providing a second particulate material,
the second particulate material being formed from particles having a D50 size of between
50 micrometres and 80 micrometres; mixing the first particulate material and the second
particulate in an aqueous solution to form a slurry; casting the slurry; and drying
the cast slurry to form a solid substrate.
[0014] The inventors of the present invention have identified that an aerosol-forming substrate
comprising particles having a D50 size of between 2 micrometres and 20 micrometres,
or 'small' particles, may disadvantageously exhibit agglomeration during manufacturing
and processing. In addition, where the aerosol-forming substrate is formed as a thin
sheet, the sheet may exhibit defects including stretch marks and slits. However, aerosol-forming
substrates comprising particles having a D50 size between 2 micrometres and 20 micrometres
result in high density aerosol-forming substrates. This may advantageously provide
enhanced aerosol generation over the whole duration of the user experience of the
aerosol-forming substrate.
[0015] On the other hand, the inventors of the present invention have identified that an
aerosol-forming substrate comprising particles having a D50 size of between 50 micrometres
and 80 micrometres, or 'large' particles, may advantageously be more straightforward
to handle during manufacture and processing since the particles do not exhibit agglomeration
to the same extent. In addition, where the aerosol-forming substrate is formed as
a sheet, the sheet may be less likely to exhibit defects, allowing the particles to
be more readily formed into a thin sheet. However, aerosol-forming substrates comprising
particles having a D50 size of between 50 micrometres and 80 micrometres result in
lower density aerosol-forming substrates which exhibit a drop or fading of aerosol
delivery over the experience of the aerosol-forming substrate.
[0016] By providing an aerosol-forming substrate comprising a first particulate material
comprising particles having a D50 size between 2 micrometres and 20 micrometres, and
a second particulate material comprising particles having a D50 size of between 50
micrometres and 80 micrometres, the inventors have found that the advantageous properties
of both particle sizes may be realised. At the same time, the disadvantageous properties
of each particle size may be mitigated.
[0017] In other words, the inventors have found that the provision of an aerosol-forming
substrate comprising a first particulate material being formed from particles having
a D50 size of between 2 micrometres and 20 micrometres, and a second particulate material
being formed from particles having a D50 size of between 50 micrometres and 80 micrometres
may advantageously be straightforward to handle during manufacturing and processing
and may exhibit good aerosol generation over the whole duration of the user experience
of the aerosol-forming substrate.
[0018] As used herein with reference to the present invention, the term "D50 size" refers
to the median particle size of the particulate material. The D50 size is the particle
size which splits the distribution in half, where half of the particles are larger
than the D50 size and half of the particles are smaller than the D50 size. The particle
size distribution may be determined by laser diffraction. For example, the particle
size distribution may be determined by laser diffraction using a Malvern Mastersizer
3000 laser diffraction particle size analyser in accordance with the manufacturer's
instructions.
[0019] In use, the aerosol-forming substrate may form part of an aerosol generating article
which may be inserted into an aerosol generating device. The aerosol generating device
may include a heater which heats the aerosol-forming substrate to release an aerosol
which may be delivered to a user. The aerosol-forming substrate may release an aerosol
when it is heated to at least about 100 degrees Celsius, at least about 200 degrees
Celsius, at least about 250 degrees Celsius, at least about 350 degrees Celsius, or
at least about 500 degrees Celsius. For example, the aerosol-forming substrate may
release an aerosol when it is heated to between about 100 degrees Celsius and about
850 degrees Celsius, between about 200 degrees Celsius and about 600 degrees Celsius,
or between about 250 degrees Celsius about 400 degrees Celsius. For example, the aerosol-forming
substrate may release an aerosol when it is heated to about 260 degrees Celsius.
[0020] As used herein with reference to the present invention, the term "aerosol-forming
substrate" refers to a substrate that is capable of producing upon heating volatile
compounds, which can form an aerosol. The aerosol generated from aerosol-forming substrate
may be visible to the human eye 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.
[0021] The second particulate material may be formed from particles having a D50 size which
is at least 10 micrometres greater than the D50 size of the first particulate material.
For example, the second particulate material may be formed from particles having a
D50 size which is at least 10 micrometres greater, 15 micrometres greater, 20 micrometres
greater, 30 micrometres greater, 40 micrometres greater, or 50 micrometres greater
than the D50 size of the first particulate material.
[0022] The second particulate material may be formed from particles having a D50 size which
is no more than 100 micrometres greater than the D50 size of the first particulate
material. For example, the second particulate material may be formed from particles
having a D50 size which is no more than 90 micrometres greater, 80 micrometres greater,
70 micrometres greater, 60 micrometres greater, 55 micrometres greater, or 50 micrometres
greater than the D50 size of the first particulate material.
[0023] The first particulate material and the second particulate material may be bonded
together using a binder to form the aerosol-forming substrate.
[0024] The first particulate material and the second particulate material may be bonded
together using pressure to form the aerosol-forming substrate.
[0025] The first particulate material and the second particulate material may be bonded
together using a pressing process, an extrusion process or a cast process.
[0026] The aerosol-forming substrate may have a large surface area.
[0027] The aerosol-forming substrate may be a sheet, a strip, a rod or a pellet.
[0028] The aerosol-forming substrate may be manufactured by any method. The aerosol-forming
substrate may be manufactured using a pressing process. The aerosol-forming substrate
may be manufactured using an extrusion process. The aerosol-forming substrate may
be manufactured using a cast process. The process may include steps of forming a slurry
of the first and second particulate materials in an aqueous solution. The aqueous
solution may further comprise a binder. The slurry may then be cast, for example using
a continuous casting process. The cast slurry may then be dried to form a solid unitary
body comprising the first particulate material and the second particulate material.
The cast slurry may be dried to form a solid unitary body having any desired geometry
through use of an appropriate mould. In some examples, the cast slurry may be dried
to form a sheet. The sheet may be crimped and folded to form the finished aerosol-forming
substrate. In some examples, the sheet may be over-crimped to sever the sheet into
a plurality of strips. In other examples, the cast slurry may be dried to form a strip,
a rod or a pellet.
[0029] The aerosol-forming substrate may include any proportion of the first particulate
material and the second particulate material. The ratio of the mass of the first particulate
material to the mass of the second particulate material in the aerosol-forming substrate
may be greater than 1. In other words, by mass, the aerosol-forming substrate may
comprise more of the first particulate material than the second particulate material.
[0030] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be no more than 1. In other
words, by mass, the aerosol-forming substrate may comprise more of the second particulate
material than the first particulate material.
[0031] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be no more than 5:1. For
example, the ratio of the mass of the first particulate material to the mass of the
second particulate material in the aerosol-forming substrate may be no more than 3:1,
no more than 1.
[0032] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be no more than 1:2. In
other words, by mass, there is at least twice as much of the second particulate material
as the first particulate material.
[0033] The inventors have found that where more than one third by mass of the particulate
material in the aerosol-forming substrate comprises the first particulate material,
being formed from particles having a D50 size of between 2 micrometres and 20 micrometres,
the aerosol-forming substrate may exhibit defects such as cracking or slits.
[0034] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be at least 1:10. For example,
the ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be at least 1:8, at least
1:5, or at least 1:3.
[0035] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be between 1:10 and 5:1,
between 1:8 and 3:1, between 1:5 and 1, between 1:5 and 1:2, between 1:3 and 1:2.
The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate may be about 1:2.
[0036] The aerosol-forming substrate may have a first particulate material content of greater
than 1 weight percent.
[0037] As used herein with reference to the invention, all weight percentages are given
on a dry weight basis.
[0038] The aerosol-forming substrate may have a first particulate material content of greater
than 5 weight percent, greater than 8 weight percent, greater than 10 weight percent,
or greater than 13 weight percent.
[0039] The aerosol-forming substrate may have a first particulate material content of no
more than 30 weight percent. For example, the aerosol-forming substrate may have a
first particulate material content of no more than 25 weight percent, no more than
20 weight percent, or no more than 17 weight percent.
[0040] The aerosol-forming substrate may have a first particulate material content of between
5 weight percent and 30 weight percent. For example, the aerosol-forming substrate
may have a first particulate material content of between 5 weight percent and 25 weight
percent, between 5 weight percent and 20 weight percent, or between 5 weight percent
and 17 weight percent.
[0041] The aerosol-forming substrate may have a first particulate material content of between
8 weight percent and 30 weight percent. For example, the aerosol-forming substrate
may have a first particulate material content of between 10 weight percent and 30
weight percent, or between 13 weight percent and 30 weight percent.
[0042] The aerosol-forming substrate may have a first particulate material content of between
8 weight percent and 25 weight percent. For example, the aerosol-forming substrate
may have a first particulate material content of between 10 weight percent and 20
weight percent, or between 13 weight percent and 17 weight percent.
[0043] The aerosol-forming substrate may have a first particulate material content of about
15 weight percent.
[0044] The aerosol-forming substrate may have a second particulate material content of greater
than 2 weight percent.
[0045] The aerosol-forming substrate may have a second particulate material content of greater
than 10 weight percent, greater than 16 weight percent, greater than 20 weight percent,
or greater than 26 weight percent.
[0046] The aerosol-forming substrate may have a second particulate material content of no
more than 60 weight percent. For example, the aerosol-forming substrate may have a
second particulate material content of no more than 50 weight percent, no more than
40 weight percent, or no more than 34 weight percent.
[0047] The aerosol-forming substrate may have a second particulate material content of between
10 weight percent and 60 weight percent. For example, the aerosol-forming substrate
may have a second particulate material content of between 10 weight percent and 50
weight percent, between 10 weight percent and 40 weight percent, or between 10 weight
percent and 34 weight percent.
[0048] The aerosol-forming substrate may have a second particulate material content of between
16 weight percent and 60 weight percent. For example, the aerosol-forming substrate
may have a second particulate material content of between 20 weight percent and 60
weight percent, or between 26 weight percent and 60 weight percent.
[0049] The aerosol-forming substrate may have a second particulate material content of between
20 weight percent and 40 weight percent. For example, the aerosol-forming substrate
may have a first particulate material content of between 26 weight percent and 34
weight percent.
[0050] The aerosol-forming substrate may have a second particulate material content of about
30 weight percent.
[0051] The aerosol-forming substrate may further comprise one or more aerosol formers.
[0052] The provision of one or more aerosol formers advantageously helps the aerosol-forming
substrate to generate an aerosol when the aerosol-forming substrate is heated.
[0053] The one or more aerosol formers may comprise glycerine. The one or more aerosol formers
may comprise propylene glycol. The one or more aerosol formers may include a combination
of glycerine and propylene glycol.
[0054] The aerosol-forming substrate may have an aerosol former content of greater than
0.5 weight percent. The aerosol-forming substrate may have an aerosol former content
of greater than 10 weight percent. The aerosol-forming substrate may have an aerosol
former content of greater than 20 weight percent weight percent. The aerosol-forming
substrate may have an aerosol former content of greater than 30 weight percent. The
aerosol-forming substrate may have an aerosol former content of greater than 40 weight
percent.
[0055] The aerosol-forming substrate may have an aerosol former content of no more than
80 weight percent. The aerosol-forming substrate may have an aerosol former content
of no more than 70 weight percent. The aerosol-forming substrate may have an aerosol
former content of no more than 60 weight percent. The aerosol-forming substrate may
have an aerosol former content of no more than 50 weight percent. The aerosol-forming
substrate may have an aerosol former content of no more than 42 weight percent.
[0056] In some instances, it has been found that aerosol-forming substrates having an aerosol
former content of more than about 42 weight percent were difficult to manufacture.
[0057] The first particulate material may be formed from particles having a D50 size of
between 2 micrometres and 20 micrometres, between 5 micrometres and 20 micrometres,
between 10 micrometres and 20 micrometres, or between 15 micrometres and 20 micrometres.
[0058] The first particulate material may be formed from particles having a D50 size of
between 2 micrometres and 15 micrometres, between 2 micrometres and 10 micrometres,
or between 2 micrometres and 5 micrometres.
[0059] The first particulate material may be formed from particles having a D50 size of
between 5 micrometres and 15 micrometres. The first particulate material may be formed
from particles having a D50 size of about 10 micrometres.
[0060] The second particulate material may be formed from particles having a D50 size of
between 50 micrometres and 80 micrometres, between 60 micrometres and 80 micrometres,
between 70 micrometres and 80 micrometres, or between 75 micrometres and 80 micrometres.
[0061] The second particulate material may be formed from particles having a D50 size of
between 50 micrometres and 75 micrometres, between 50 micrometres and 70 micrometres,
or between 50 micrometres and 60 micrometres.
[0062] The second particulate material may be formed from particles having a D50 size of
between 55 micrometres and 65 micrometres. The second particulate material may be
formed from particles having a D50 size of about 59 micrometres.
[0063] The first particulate material may be formed from particles having a D50 size of
10 micrometres, and the second particulate material may be formed from particles having
a D50 size of 59 micrometres.
[0064] It has been found that the provision of an aerosol-forming substrate comprising a
first particulate material and a second particulate material having these D50 sizes
may advantageously exhibit both improved handling during manufacture, as well as good
delivery of aerosol during use.
[0065] The first particulate material may be formed from particles having a D95 size of
at least 10 micrometres.
[0066] As used herein with reference to the present invention, the term "D95 size" is the
size at which the proportion by mass of particles with sizes below this value is 95
percent.
[0067] The first particulate material may be formed from particles having a D95 size of
at least 15 micrometres, at least 20 micrometres, or at least 30 micrometres.
[0068] The first particulate material may be formed from particles having a D95 size of
no more than 60 micrometres, no more than 50 micrometres, or no more than 40 micrometres.
[0069] The first particulate material may be formed from particles having a D95 between
10 micrometres and 60 micrometres, between 15 micrometres and 50 micrometres, between
20 micrometres and 40 micrometres, or between 30 micrometres and 40 micrometres.
[0070] The second particulate material may be formed from particles having a D95 size of
at least 80 micrometres.
[0071] The second particulate material may be formed from particles having a D95 size of
at least 90 micrometres, at least 100 micrometres, or at least 110 micrometres.
[0072] The second particulate material may be formed from particles having a D95 size of
no more than 130 micrometres, no more than 125 micrometres, or no more than 120 micrometres.
[0073] The second particulate material may be formed from particles having a D95 between
80 micrometres and 130 micrometres, between 90 micrometres and 125 micrometres, between
100 micrometres and 120 micrometres, or between 110 micrometres and 120 micrometres.
[0074] The first particulate material may be formed from particles having a D95 size of
33 micrometres. The second particulate material may be formed from particles having
a D95 size of 116 micrometres.
[0075] The second particulate material may be formed from particles having a D95 size which
is at least 40 micrometres greater than the D95 size of the first particulate material.
For example, the second particulate material may be formed from particles having a
D95 size which is at least 50 micrometres greater, 60 micrometres greater, 70 micrometres
greater, or 80 micrometres greater than the D95 size of the first particulate material.
[0076] The second particulate material may be formed from particles having a D95 size which
is no more than 200 micrometres greater than the D95 size of the first particulate
material. For example, the second particulate material may be formed from particles
having a D95 size which is no more than 180 micrometres greater, 150 micrometres greater,
120 micrometres greater, 100 micrometres greater, 90 micrometres greater, or 80 micrometres
greater than the D95 size of the first particulate material.
[0077] The first particulate material may be formed from particles having a diameter of
at least 5 micrometres. For example, the first particulate material may be formed
from particles having a diameter of at least 10 micrometres, at least 20 micrometres,
or at least 30 micrometres.
[0078] As used herein with reference to the present invention, the term "diameter" refers
to a straight line distance between two points on the surface of a particle. Where
the straight line distance between the two most distant points on the surface of a
particle is 5 micrometres, it will be understood the particle has a diameter of at
least 5 micrometres. Use of the term "diameter" does not imply that the particles
being characterized are spherical. Where the particle is a fibre, the "diameter" will
correspond to the length of the fibre.
[0079] The first particulate material may be formed from particles having a diameter of
no more than 40 micrometres. For example, the first particulate material may be formed
from particles having a diameter of no more than 50 micrometres, no more than 40 micrometres,
or no more than 35 micrometres.
[0080] The first particulate material may be formed from particles having a diameter between
5 micrometres and 40 micrometres, between 10 micrometres and 35 micrometres, or between
20 micrometres and 30 micrometres.
[0081] The second particulate material may be formed from particles having a diameter of
at least 50 micrometres. For example, the second particulate material may be formed
from particles having a diameter of at least 80 micrometres, at least 100 micrometres,
or at least 125 micrometres.
[0082] The second particulate material may be formed from particles having a diameter of
no more than 250 micrometres. For example, the second particulate material may be
formed from particles having a diameter of no more than 225 micrometres, no more than
200 micrometres, or no more than 150 micrometres.
[0083] The second particulate material may be formed from particles having a diameter between
50 micrometres and 250 micrometres, between 80 micrometres and 225 micrometres, or
between 100 micrometres and 125 micrometres.
[0084] The first particulate material may be formed from particles having a diameter between
5 micrometres and 40 micrometres, and the second particulate material may be formed
from particles having a diameter of between 50 micrometres and 250 micrometres.
[0085] The first particulate material and the second particulate material may be formed
from different materials.
[0086] The first particulate material and the second particulate material may be formed
from the same material.
[0087] At least one of the first particulate material and the second particulate material
may comprise one or more of cellulose and microcrystalline cellulose (MCC).
[0088] The first particulate material may comprise cellulose. The first particulate material
may comprise microcrystalline cellulose. The second particulate material may comprise
cellulose. The second particulate material may comprise microcrystalline cellulose.
[0089] The cellulose or microcrystalline cellulose may advantageously increase the tensile
strength of the aerosol-forming substrate.
[0090] Both the first particulate material and the second particulate material may comprise
one or more of cellulose and microcrystalline cellulose (MCC).
[0091] The particles of the first and second particulate materials may be fibres. Where
this is the case, the first particulate material may be a first fibrous material and
the second particulate material may be a second fibrous material.
[0092] The particles of the first particulate material and the second particulate material
may form a bimodal size distribution, wherein a first peak of the bimodal size distribution
corresponds to the first particulate material and a second peak of the bimodal size
distribution corresponds to the second particulate material.
[0093] As used herein with reference to the present invention, a "bimodal size distribution"
refers to a particle size frequency distribution with two different modes or peaks.
The first peak corresponds to the first particulate material and the second peak corresponds
to the second particulate material.
[0094] The aerosol-forming substrate may be a strip.
[0095] The aerosol-forming substrate may be a rod.
[0096] The aerosol-forming substrate may be a pellet.
[0097] The aerosol-forming substrate may be a sheet.
[0098] As used herein with reference to the present invention, the term "sheet" denotes
a laminar element having a width and length substantially greater than the thickness
thereof.
[0099] The sheet may be a gathered sheet. As used herein with reference to the invention,
the term "gathered" denotes that the sheet is convoluted, folded, or otherwise compressed
or constricted. The sheet may be folded substantially transversely to a cylindrical
axis of the aerosol generating article.
[0100] Sheets according to the invention do not comprise flowable liquid. Consequently,
users of aerosol generating rods and aerosol generating articles according to the
invention are advantageously not required to handle liquid formulations.
[0101] E-cigarettes typically use a liquid formulation comprising free nicotine base. Nicotine
salts may be more stable than free nicotine base. Consequently, aerosol-forming substrate
according to the invention may advantageously have longer shelf lives than liquid
formulations typical used in e-cigarettes.
[0102] The aerosol-forming substrate may further comprise a binder.
[0103] Inclusion of a binder may advantageously facilitate manufacture of the aerosol-forming
substrate.
[0104] Inclusion of a binder may advantageously improve the homogeneity of the aerosol-forming
substrate compared to an aerosol-forming substrate in which no binder is included.
[0105] The aerosol-forming substrate may comprise a gum binder.
[0106] The aerosol-forming substrate may comprise a natural gum binder. The aerosol-forming
substrate may comprise one or more natural gum binders selected from the group consisting
of guar gum, xanthan gum, natural gum, and gum arabic.
[0107] The aerosol-forming substrate may have a binder content of greater than 1 weight
percent. For example, the aerosol-forming substrate may have a binder content of greater
than 2 weight percent, or greater than 3 weight percent.
[0108] The aerosol-forming substrate may a have a binder content of no more than 10 weight
percent. For example, the aerosol-forming substrate may have a binder content of no
more than 8 weight percent, or no more than 6 weight percent.
[0109] The aerosol-forming substrate may have a binder content of between 1 weight percent
and 10 weight percent, between 1 weight percent and 8 weight percent, or between 1
weight percent and 6 weight percent.
[0110] The aerosol-forming substrate may have a binder content of between 2 weight percent
and 10 weight percent, between 2 weight percent and 8 weight percent, or between 2
weight percent and 6 weight percent.
[0111] The aerosol-forming substrate may have a binder content of between 3 weight percent
and 10 weight percent, between 3 weight percent and 8 weight percent, or between 3
weight percent and 6 weight percent.
[0112] The aerosol-forming substrate may have a binder content of about 5 weight percent.
[0113] The binder may comprise carboxymethyl cellulose (CMC).
[0114] Advantageously, carboxymethyl cellulose may provide quicker delivery of an aerosol
in aerosol-forming substrates comprising CMC. In particular, it has been found that
aerosol-forming substrates using CMC as a binder exhibit good aerosol delivery from
the first puff comparted to aerosol-forming substrates which use other binders.
[0115] The carboxymethyl cellulose may comprise sodium carboxymethyl cellulose. Advantageously,
the present inventors have found that sodium carboxymethyl cellulose is a carboxymethyl
cellulose that may be particularly effective at providing quick aerosol delivery from
early on in the user experience.
[0116] The aerosol-forming substrate may comprise nicotine.
[0117] The nicotine may comprise one or more nicotine salts. The one or more nicotine salts
may be selected from the list consisting of nicotine lactate, nicotine citrate, nicotine
pyruvate, nicotine bitartrate, nicotine benzoate, nicotine pectate, nicotine alginate,
and nicotine salicylate.
[0118] The nicotine may comprise an extract of tobacco.
[0119] The aerosol-forming substrate may have a nicotine content of greater than 0.5 weight
percent. For example, the aerosol-forming substrate may have a nicotine content of
greater than 1 weight percent, greater than 2 weight percent, greater than 3 weight
percent, greater than 5 weight percent, or 8 weight percent.
[0120] The aerosol-forming substrate may have a nicotine content of no more than 10 weight
percent. For example, the aerosol-forming substrate may have a nicotine content of
no more than 8 weight percent, no more than 5 weight percent, no more than 3 weight
percent, no more than 2 weight percent, or no more than 1 weight percent.
[0121] The aerosol-forming substrate may have a nicotine content of between 0.5 weight percent
and 10 weight percent. For example, the aerosol-forming substrate may have a nicotine
content of between 0.5 weight percent and 8 weight percent, between 0.5 weight percent
and 5 weight percent, between 0.5 weight percent and 3 weight percent, between 0.5
weight percent and 2 weight percent, or between 0.5 weight percent and 1 weight percent.
[0122] The aerosol-forming substrate may have a nicotine content of between 1 weight percent
and 5 weight percent. For example, the aerosol-forming substrate may have a nicotine
content of between 1 weight percent and 3 weight percent, or between 1 weight percent
and 2 weight percent. The aerosol-forming substrate may have a nicotine content of
about 1.5 weight percent.
[0123] The aerosol-forming substrate may comprise one or more carboxylic acids. Advantageously,
including one or more carboxylic acids in the aerosol-forming substrate may create
a nicotine salt.
[0124] The one or more carboxylic acids comprise one or more of lactic acid and levulinic
acid. Advantageously, the present inventors have found that lactic acid and levulinic
acid are particularly good carboxylic acids for creating nicotine salts.
[0125] The aerosol-forming substrate may have a carboxylic acid content of greater than
0.5 weight percent. For example, the aerosol-forming substrate may have a carboxylic
acid content of greater than 1 weight percent, greater than 2 weight percent, or greater
than 3 weight percent.
[0126] The aerosol-forming substrate may have a carboxylic acid content of no more than
15 weight percent. For example, the aerosol-forming substrate may have a carboxylic
acid content of no more than 10 weight percent, no more than 5 weight percent, or
no more than 3 weight percent.
[0127] The aerosol-forming substrate may have a carboxylic acid content of between 0.5 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a carboxylic acid content of between 0.5 weight percent and 10 weight percent, between
0.5 weight percent and 5 weight percent, or between 0.5 weight percent and 3 weight
percent.
[0128] The aerosol-forming substrate may have a carboxylic acid content of between 2 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a carboxylic acid content of between 2 weight percent and 10 weight percent, between
2 weight percent and 5 weight percent, or between 2 weight percent and 3 weight percent.
The aerosol-forming substrate may have a carboxylic acid content of about 2.5 weight
percent. The aerosol-forming substrate may have a lactic acid content of about 2.5
weight percent.
[0129] The aerosol-forming substrate may comprise one or more disaccharides such as lactose,
sucrose and trehalose, one or more sugar alcohols such as mannitol and sorbitol or
a combination of one or more disaccharides and one or more sugar alcohols.
[0130] The aerosol-forming substrate may have a disaccharide content of greater than 0.5
weight percent. For example, the aerosol-forming substrate may have a disaccharide
content of greater than 1 weight percent, greater than 2 weight percent, or greater
than 3 weight percent.
[0131] The aerosol-forming substrate may have a disaccharide content of no more than 15
weight percent. For example, the aerosol-forming substrate may have a disaccharide
content of no more than 10 weight percent, no more than 8 weight percent, or no more
than 5 weight percent.
[0132] The aerosol-forming substrate may have a disaccharide content of between 0.5 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a disaccharide content of between 0.5 weight percent and 10 weight percent, between
0.5 weight percent and 8 weight percent, or between 0.5 weight percent and 5 weight
percent.
[0133] The aerosol-forming substrate may have a disaccharide content of between 3 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a disaccharide content of between 3 weight percent and 10 weight percent, or between
3 weight percent and 8 weight percent. The aerosol-forming substrate may have a disaccharide
content of about 2.5 weight percent. The aerosol-forming substrate may have a sucrose
content of about 2.5 weight percent.
[0134] The aerosol-forming substrate may comprise cellulose strengthening fibres.
[0135] The cellulose strengthening fibres may have a D50 size of at least 0.2 millimetres,
at least 0.5 millimetres, at least 0.7 millimetres, or at least 0.9 millimetres.
[0136] The cellulose strengthening fibres may have a D50 size of no more than 2.0 millimetres,
no more than 1.8 millimetres, no more than 1.6 millimetres, or no more than 1.4 millimetres.
[0137] For example, the cellulose strengthening fibres may have a D50 size of between 0.2
millimetres and 2.0 millimetres, between 0.5 millimetres and 1.8 millimetres, between
0.7 millimetres and 1.6 millimetres, or between 0.9 millimetres and 1.4 millimetres.
[0138] The cellulose strengthening fibres may have a D50 size of between 0.2 millimetres
and 1.8 millimetres, between 0.2 millimetres and 1.6 millimetres, or between 0.2 millimetres
and 1.4 millimetres.
[0139] The cellulose strengthening fibres may have a D50 size of between 0.5 millimetres
and 2.0 millimetres, between 0.5 millimetres and 1.6 millimetres, or between 0.5 millimetres
and 1.4 millimetres.
[0140] The cellulose strengthening fibres may have a D50 size of between 0.7 millimetres
and 2.0 millimetres, between 0.7 millimetres and 1.8 millimetres, or between 0.7 millimetres
and 1.4 millimetres.
[0141] Advantageously, the present inventors have found that cellulose fibres may act as
a strengthening agent that is particularly effective at increasing the tensile strength
of an aerosol-forming substrate. Accordingly, these cellulose fibres may be referred
to as cellulose strengthening fibres.
[0142] The cellulose strengthening fibres may have a particle diameter of at least 0.2 millimetres,
at least 0.5 millimetres, at least 0.7 millimetres, or at least 0.9 millimetres.
[0143] The cellulose strengthening fibres may have a particle diameter of no more than 2.0
millimetres, no more than 1.8 millimetres, no more than 1.6 millimetres, or no more
than 1.4 millimetres.
[0144] For example, the cellulose strengthening fibres may have a particle diameter of between
0.2 millimetres and 2.0 millimetres, between 0.5 millimetres and 1.8 millimetres,
between 0.7 millimetres and 1.6 millimetres, or between 0.9 millimetres and 1.4 millimetres.
[0145] The cellulose strengthening fibres may have a particle diameter of between 0.2 millimetres
and 1.8 millimetres, between 0.2 millimetres and 1.6 millimetres, or between 0.2 millimetres
and 1.4 millimetres.
[0146] The cellulose strengthening fibres may have a particle diameter of between 0.5 millimetres
and 2.0 millimetres, between 0.5 millimetres and 1.6 millimetres, or between 0.5 millimetres
and 1.4 millimetres.
[0147] The cellulose strengthening fibres may have a particle diameter of between 0.7 millimetres
and 2.0 millimetres, between 0.7 millimetres and 1.8 millimetres, or between 0.7 millimetres
and 1.4 millimetres.
[0148] The aerosol-forming substrate may have a cellulose strengthening fibre content of
greater than 0.5 weight percent. For example, the aerosol-forming substrate may have
a cellulose strengthening fibre content of greater than 1 weight percent, greater
than 2 weight percent, or greater than 3 weight percent.
[0149] The aerosol-forming substrate may have a cellulose strengthening fibre content of
no more than 15 weight percent. For example, the aerosol-forming substrate may have
a cellulose fibre content of no more than 10 weight percent, no more than 8 weight
percent, or no more than 5 weight percent.
[0150] The aerosol-forming substrate may have a cellulose fibre content of between 0.5 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a cellulose fibre content of between 0.5 weight percent and 10 weight percent, between
0.5 weight percent and 8 weight percent, or between 0.5 weight percent and 5 weight
percent.
[0151] The aerosol-forming substrate may have a cellulose fibre content of between 3 weight
percent and 15 weight percent. For example, the aerosol-forming substrate may have
a cellulose fibre content of between 3 weight percent and 10 weight percent, or between
3 weight percent and 8 weight percent. The aerosol-forming substrate may have a cellulose
fibre content of about 6 weight percent.
[0152] The aerosol-forming substrate may further comprise one or more of nicotine, lactic
acid, and sucrose.
[0153] The first particulate material may have any density. The first particulate material
may have a density of greater than 0.5 grams per centimetre cubed. For example, the
first particulate material may have a density of greater than 1.0 grams per centimetre
cubed, greater than 1.5 grams per centimetre cubed, greater than 3.0 grams per centimetre
cubed, or greater than 5.0 grams per centimetre cubed.
[0154] As set out above, the provision of a first particulate material having a relatively
high density may advantageously provide enhanced aerosol generation over the whole
duration of the user experience of the aerosol-forming substrate.
[0155] The second particulate material may have any density. The second particulate material
may have a density of greater than 0.1 grams per centimetre cubed. For example, the
first particulate material may have a density of greater than 0.3 grams per centimetre
cubed, greater than 0.5 grams per centimetre cubed, or greater than 0.6 grams per
centimetre cubed.
[0156] The second particulate material may have a density of no more than 2.0 grams per
centimetre cubed. For example, the first particulate material may have a density of
no more than 1.5 grams per centimetre cubed, no more than 1.0 grams per centimetre
cubed, or greater than 0.8 grams per centimetre cubed.
[0157] The second particulate material may have a density of between 0.1 grams per centimetre
cubed and 2.0 grams per centimetre cubed. For example, the second particulate material
may have a density of between 0.3 grams per centimetre cubed and 1.5 grams per centimetre
cubed, between 0.5 grams per centimetre cubed and 1.0 grams per centimetre cubed,
or between 0.5 grams per centimetre cubed and 0.8 grams per centimetre cubed.
[0158] The second particulate material may have a density of between 0.6 grams per centimetre
cubed and 0.8 grams per centimetre cubed.
[0159] As set out above, the provision of a second particulate material having a relatively
low density may advantageously improve the physical properties of the aerosol-forming
substrate making it less prone to exhibit defects.
[0160] The aerosol-forming substrate may not comprise tobacco.
[0161] According to the present invention, there is also provided aerosol generating article
comprising an aerosol-forming substrate as described above.
[0162] As used herein, the term "aerosol generating article" refers to an article for producing
an aerosol. An aerosol generating article typically comprises an aerosol-forming substrate
that is suitable and intended to be heated or combusted in order to release volatile
compounds that can form an aerosol. A conventional cigarette is lit when a user applies
a flame to one end of the cigarette and draws air through the other end. The localised
heat provided by the flame and the oxygen in the air drawn through the cigarette causes
the end of the cigarette to ignite, and the resulting combustion generates an inhalable
smoke. By contrast, in "heated aerosol generating articles", an aerosol is generated
by heating an aerosol-forming substrate and not by combusting the aerosol-forming
substrate. Known heated aerosol generating articles include, for example, electrically
heated aerosol generating articles.
[0163] The aerosol generating article may include a hollow cellulose acetate tube. The aerosol
generating article may include a spacer element. The aerosol generating article may
include a mouthpiece filter. The aerosol-forming substrate, the hollow cellulose acetate
tube, the spacer element and the mouthpiece filter may be arranged sequentially. The
aerosol-forming substrate, the hollow cellulose acetate tube, the spacer element and
the mouthpiece filter may be arranged in a coaxial alignment.
[0164] The aerosol generating article may include a cigarette paper.
[0165] The aerosol-forming substrate, the hollow cellulose acetate tube, the spacer element
and the mouthpiece filter may be assembled by a cigarette paper.
[0166] The aerosol generating article may have a mouth-end and a distal end. In use, a user
may insert the mouth-end into their mouth.
[0167] The aerosol generating article may be suitable for use with an electrically-operated
aerosol generating device comprising a heater for heating the aerosol-forming substrate.
[0168] The aerosol-forming substrate may be provided in the form of a plug.
[0169] The aerosol generating article may comprise a susceptor. The susceptor may be a plurality
of susceptor particles which may be deposited on or embedded within the aerosol-forming
substrate. The susceptor particles may be immobilized by the aerosol-forming substrate
and remain at an initial position. The susceptor particles may be homogeneously distributed
in the aerosol- forming substrate. Due to the particulate nature of the susceptor,
heat may be produced according to the distribution of the particles in the aerosol-forming
substrate. Alternatively, the susceptor may be in the form of one or more sheets,
strips, shreds or rods that may be placed next to or embedded in the aerosol-forming
substrate. The aerosol-forming substrate may comprise one or more susceptor strips.
[0170] The invention is defined in the claims.
[0171] Examples will now be further described with reference to the figure in which:
Figure 1 illustrates an example of an aerosol generating article containing the aerosol-forming
substrate as described herein;
Figure 2 is a plot of glycerol delivery per puff as a function of puff number for
a three of aerosol generating articles each containing a different aerosol-forming
substrate;
Figure 3 is a plot of nicotine delivery per puff as a function of puff number for
a three of aerosol generating articles each containing a different aerosol-forming
substrate; and
Figure 4 is an illustrative plot of the particle size distribution of an aerosol-forming
substrate according to the present invention.
[0172] Figure 1 illustrates an example of an aerosol generating article 1000 containing
an aerosol-forming substrate as described herein.
[0173] In the example of Figure 1, the aerosol generating article 1000 includes four elements:
the aerosol-forming substrate 1020, a hollow cellulose acetate tube 1030, a spacer
element 1040, and a mouthpiece filter 1050. The four elements 1020, 1030, 1040, 1050
are arranged sequentially and in a coaxial alignment. The four elements 1020, 1030,
1040, 1050 are assembled by a cigarette paper 1060 to form the aerosol generating
article 1000.
[0174] In the example of Figure 1, the aerosol generating article 1000 has a mouth-end 1012
and a distal end 1013. A user may insert the mouth-end 1012 into their mouth during
use. The distal end 1013 is located at the opposite end of the aerosol generating
article 1000 to the mouth end 1012. The example of an aerosol generating article 1000
illustrated in Figure 1 is particularly suitable for use with an electrically-operated
aerosol generating device comprising a heater for heating the aerosol-forming substrate.
[0175] In one example, when assembled, the aerosol generating article 1000 is about 45 millimetres
in length and has an outer diameter of about 7.2 millimetres and an inner diameter
of about 6.9 millimetres.
[0176] In the example of Figure 1, the aerosol-forming substrate 1020 is provided in the
form of a plug made by crimping a sheet of aerosol-forming substrate. The sheet is
gathered, crimped and wrapped in a filter paper (not shown) to form the plug.
[0177] The aerosol-forming substrate 1020 comprises a first particulate material and a second
particulate material. The first particulate material is formed from particles having
a D50 size of about 10 micrometres and a D95 size of about 33 micrometres. The second
particulate material is formed from particles having a D50 size of about 59 micrometres
and a D95 size of about 116 micrometres.
[0178] The first particulate material is formed from particles having a diameter of between
5 micrometres and 40 micrometres, and the second particulate material is formed from
particles having a diameter of between 50 micrometres and 250 micrometres.
[0179] The ratio of the mass of the first particulate material to the mass of the second
particulate material in the aerosol-forming substrate is about 1:2.
[0180] The first and second particulate materials are formed from microcrystalline cellulose
(MCC).
[0181] The first particulate material has a density greater than 1.0 grams per centimetre
cubed. The second particulate material has a density of between 0.5 grams per centimetre
cubed and 1.0 grams per centimetre cubed.
[0182] The aerosol-forming substrate 1020 comprises about 15 weight percent of the first
particulate material.
[0183] The aerosol-forming substrate 1020 comprises about 30 weight percent of the second
particulate material.
[0184] The aerosol-forming substrate 1020 further comprises about 30 weight percent glycerine
as an aerosol former.
[0185] The aerosol-forming substrate 1020 further comprises about 5 weight percent carboxymethyl
cellulose as a binder.
[0186] The aerosol-forming substrate 1020 further comprises about 6 weight percent cellulose
strengthening fibres.
[0187] The aerosol-forming substrate 1020 further comprises about 1.5 weight percent nicotine.
[0188] The aerosol-forming substrate 1020 further comprises about 2.5 weight percent lactic
acid.
[0189] The aerosol-forming substrate 1020 further comprises about 2.5 weight percent sucrose.
[0190] An aerosol generating article 1000 as illustrated in Figure 1 is designed to engage
with an aerosol generating device in order to be consumed. Such an aerosol generating
device includes means for heating the aerosol-forming substrate 1020 to a sufficient
temperature to form an aerosol. Typically, the aerosol generating device may comprise
a heating element that surrounds the aerosol generating article 1000 adjacent to the
aerosol-forming substrate 1020, or a heating element that is inserted into the aerosol-forming
substrate 1020.
[0191] Once engaged with an aerosol generating device, a user draws on the mouth-end 1012
of the smoking article 1000 and the aerosol-forming substrate 1020 is heated to a
temperature of about 260 degrees Celsius. At this temperature, volatile compounds
are evolved from the aerosol-forming substrate 1020. These compounds condense to form
an aerosol. The aerosol is drawn through the filter 1050 and into the user's mouth.
[0192] Figure 2 shows the result of a study to determine the delivery of glycerol per puff
as a function of the puff number for three aerosol generating articles each containing
a different aerosol-forming substrate.
[0193] The first aerosol-forming substrate is a reference substrate which was a heat stick
for use with an IQOS heating device manufactured by Philip Morris Products. The reference
substrate comprises cast leaf tobacco. The line corresponding to the first aerosol-forming
substrate is identified as 2003.
[0194] The second aerosol-forming substrate comprises about 13.3 weight percent of the first
particulate material and about 26.7 weight percent of the second particulate material.
Accordingly, in the second aerosol-forming substrate, the ratio of the mass of the
first (smaller) particulate material to the mass of the second (larger) particulate
material in the aerosol-forming substrate is about 1:2. The line corresponding to
the second aerosol-forming substrate is identified as 2004. The second aerosol-forming
substrate is in accordance with the present invention.
[0195] The third aerosol-forming substrate comprises about 40 weight percent of the second
(larger) particulate material. The third aerosol-forming substrate does not comprise
any amount of the first (smaller) particulate material. The line corresponding to
the third aerosol-forming substrate is identified as 2005.
[0196] The glycerol yield in micrograms per puff is plotted on the vertical axis, identified
as 2001. The puff number is plotted on the horizontal axis, identified as 2002.
[0197] As can be seen from the graph shown in Figure 2, it was found that the delivery of
glycerol was advantageously sustained over the full 12 puffs in the second aerosol-forming
substrate 2004 according to the present invention. Indeed, it was advantageously demonstrated
that the second aerosol-forming substrate 2004 according to the present invention
exhibited greater glycerol yield even than the first reference aerosol-forming substrate
2003.
[0198] By contrast, the third aerosol-forming substrate 2005 which does not contain a mixture
of the first and second particulate material exhibits significantly lower delivery
of glycerol over the 12 puffs.
[0199] The test also demonstrated that providing a ratio of the mass of the first (smaller)
particulate material to the mass of the second (larger) particulate material in the
aerosol-forming substrate of about 1:2 results is favourable glycerol delivery.
[0200] Figure 3 shows the result of a study to determine the delivery of nicotine per puff
as a function of the puff number for the same three aerosol generating articles each
containing the same aerosol-forming substrates described above in reference to Figure
2.
[0201] The first aerosol-forming substrate, which is a reference substrate, is identified
as 3003.
[0202] The second aerosol-forming substrate, which is according to the present invention,
is identified as 3004.
[0203] The third aerosol-forming substrate, which does not contain a mixture of the first
and second particulate material, is identified as 3005.
[0204] The nicotine yield in micrograms per puff is plotted on the vertical axis, identified
as 3001. The puff number is plotted on the horizontal axis, identified as 3002.
[0205] As can be seen from the graph shown in Figure 3, it was found that the delivery of
nicotine was advantageously sustained over the full 12 puffs in the second aerosol-forming
substrate 3004 according to the present invention when compared to the third aerosol-forming
substrate 3005, which does not contain a mixture of the first and second particulate
material.
[0206] Figure 4 is an illustrative plot of the particle size distribution of an aerosol-forming
substrate according to the present invention. The graph shown in Figure 4 is for illustrative
purposes only and is not based on actual data. Particle size is plotted on the horizontal
axis, identified as 4001. The frequency of a given particle size is plotted on the
vertical axis, identified as 4002.
[0207] As can be seen from Figure 4, the particle size distribution of an aerosol-forming
substrate according to the present invention exhibits a bimodal distribution pattern.
The lower peak corresponds to the first (smaller) particulate material. From the lower
peak, the D50
1 figure for the first particulate material may be determined and is identified on
the graph. The D95
1 figure for the first particulate material is also identified on the graph. From the
higher peak, the D50
2 figure for the second particulate material may be determined and is identified on
the graph. The D95
2 figure for the second particulate material is also identified on the graph.
[0208] The ratio of the mass of the first (smaller) particulate material to the mass of
the second (larger) particulate material in the aerosol-forming substrate is about
1:2. This is demonstrated in the distribution on Figure 4 since the peak corresponding
to the second particulate material is approximately twice as high as the first peak
corresponding to the first particulate material.