Note: Descriptions are shown in the official language in which they were submitted.
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FILTER FOR A SMOKING ARTICLE
The present invention relates to filters for smoking articles.
It is well known that filtration of smoke in a smoking article, such as a
cigarette
may affect the taste and flavour characteristics of a product when smoked.
Filters commonly include adsorbent materials, such as activated carbon, to
reduce certain components of the smoke during smoking. However, activated
carbon in a filter can adversely affect the taste and/or flavour
characteristics of a
cigarette.
Therefore, in a first aspect, there is provided a filter element for a smoking
article, the filter element comprising a plug of filter material, and a
tobacco
thread, wherein the tobacco thread extends substantially longitudinally
through
the plug of filter material.
The inventors have found that the provision of the substantially longitudinal
tobacco thread significantly improves the flavour of smoke (which comprises
gas
and particulate matter) that is inhaled by a smoker.
Preferably, the tobacco thread extends substantially longitudinally between
mutually opposing end faces of the plug of filter material. Preferably, the
tobacco thread extends in a direction which is substantially parallel to a
side face
of the plug of filter material, which side face is preferably substantially
perpendicular to one or both end faces. Preferably, the tobacco thread extends
through an inner portion of, and is surrounded by, the filter material.
Preferably, the tobacco thread extends through substantially the centre of the
plug of filter material.
Advantageously, the tobacco thread is disposed in close proximity with the
path
of the gaseous flow as it moves through the filter element, and is therefore
able
to affect various characteristics of the gaseous flow before the flow reaches
the
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smoker's mouth. Furthermore, because the tobacco thread is disposed
substantially longitudinally within the plug of filter material, it does not
adversely
affect the direction or rate of gaseous flow, and so the smoker does not
detect a
significant difference in the resistance to draw therethrough.
The tobacco thread may comprise shredded tobacco, powdered tobacco,
reconstituted tobacco and/or cut tobacco. However, preferably the tobacco
thread comprises tobacco fibres and/or tobacco sheet. The tobacco thread may
be prepared using technology known in the art. By way of example only, a
slurry
comprising tobacco particles (e.g. tobacco dust and/or tobacco stems), and
preferably a suitable binding agent, may be prepared. The slurry may be spread
on to a support surface, such as a conveyer, to thereby form a wet tobacco
sheet.
The wet sheet may then be heated, for example, by an oven, such that the
slurry
dries, thereby forming a tobacco sheet. The tobacco sheet may then be cut to
form the thread having appropriate dimensions.
The tobacco thread may be between about 0.2mm and 5mm in diameter, and is
preferably between about 0.4mm and 3mm in diameter.
Once prepared, the tobacco thread may then be encased by filter material to
form the filter element of the first aspect. The plug of filter material may
comprise any suitable filter media, which will be known to the skilled
technician.
A preferred filter material comprises cellulose acetate. The diameter of the
plug
of filter material may be between about 5mm and 15mm, preferably between
6mm and 12mm, more preferably between 7mm and 11mm, and most preferably
between 8mm and 10mm. The diameter of the plug may be between 5 and
10mm.
Preferably, the ratio of the diameter of the plug of filter material to the
diameter
of the tobacco thread is between 2:1 and 25:1, and is more preferably between
4:1 and 10:1.
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The filter element may comprise a flavourant. In embodiments where a
flavourant is used, the flavourant may be incorporated in the plug of filter
material. However, preferably the flavourant is incorporated in the tobacco
thread. Once formed, the thread may be dipped into a vessel containing the
flavourant. However, preferably the flavourant is included in the slurry from
which the thread is prepared.
It will be appreciated that the filter element according to the first aspect
may be
used in the manufacture of a filter, for use in a smoking article.
Hence, according to a second aspect of the invention, there is provided a
filter
for a smoking article, the filter comprising a filter element according to the
first
aspect.
The filter of the second aspect may comprise a plurality of filter elements
according to
the first aspect, in which a tobacco thread extends through a plug of filter
material. For
example, the filter may comprise 2, 3, 4, 5 or more filter elements of the
first aspect, in
which adjacent filter elements may either be connected to each other, or which
elements may be separated from each other by other filter elements (which may
not be
in accordance with the first aspect).
Hence, the filter may comprise a plurality of filter elements, at least one of
which is a
filter element according to the first aspect of the invention. For example, it
is envisaged
that, in one embodiment, in addition to comprising one or more filter elements
according to the first aspect (ie. containing the tobacco thread), the filter
of the second
aspect may also comprise an adsorbent filter element, which element comprises
an
adsorbent material. The adsorbent filter element is provided to adsorb and,
hence,
reduce certain components of the smoke during smoking. The adsorbent filter
element
may comprise a plug of filter material in which the adsorbent material is
dispersed. The
filter material may be cellulose acetate. A preferred adsorbent material is
activated
carbon. The activated carbon may be in the form of granular activated carbon,
which is
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preferably distributed substantially throughout the volume of the plug of
filter material.
Preferably, the adsorbent filter element does not include a tobacco thread.
In another embodiment, in addition to comprising one or more filter elements
according to the first aspect (ie. containing the tobacco thread), the filter
of the second
aspect may also comprise a filter element, which comprises filter material
(such as,
cellulose acetate), and which does not include a tobacco thread or adsorbent
material.
The filter may comprise at least two, and preferably at least three filter
elements,
9o provided that at least one filter element is in accordance with the first
aspect.
Preferably, the filter comprises a filter element according to the first
aspect, an
adsorbent filter element comprising adsorbent, and a filter element, which
does not
include adsorbent or a tobacco thread. Preferably, multiple filter elements
are arranged
longitudinally of one another with the end face of one filter element abutting
the end
face of an adjacent filter element. It is preferred that the filter elements
have
substantially similar diameters. It should be appreciated that the various
filter elements
may be in any order in the filter, as illustrated in Figures 3 and 4.
The filter element of the first aspect, or the filter of the second aspect,
may be
incorporated into a smoking article.
Hence, according to a third aspect of the invention, there is provided a
smoking article
comprising a filter element according to the first aspect, or a filter
according to the
second aspect.
The smoking article preferably comprises a section of smokeable material, such
as
tobacco. As used herein, the term "smoking article" includes smokeable
products such
as cigarettes, cigars and cigarillos whether based on tobacco, tobacco
derivatives,
expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-
not-burn
products.
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The section of smokeable material and the filter may be attached by tipping
paper.
According to a fourth aspect of the invention, there is provided a method of
manufacturing a filter element for a smoking article, the method comprising
providing a tobacco thread through a plug of filter material, wherein the
tobacco
thread extends substantially longitudinally through the plug of filter
material.
1o The method preferably comprises a step of introducing the tobacco thread
into
substantially the centre of the filter material. The method may comprise using
guide means to guide the tobacco thread as a tow of filter material is formed
therearound. The guide means may comprise a guide tube through which the
thread is entrained. As the thread exits the guide means, it is preferably
surrounded by filter material.
All of the features described herein (including any accompanying claims,
abstract and
drawings), and/or all of the steps of any method or process so disclosed, may
be
combined with any of the above aspects in any combination, except combinations
where at least some of such features and/or steps are mutually exclusive.
For a better understanding of the invention, and to show how embodiments of
the
same may be carried into effect, reference will now be made, by way of
example, to the
accompanying Figures, in which:-
Figure 1 shows a perspective view of a smoking article, including a rod of
smokeable
material, a filter in accordance with the invention, and tipping paper
attaching the rod
and filter together;
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Figure 2 shows a cross-sectional side view of a first embodiment of the filter
according to the invention;
Figure 3 shows a cross-sectional side view of a second embodiment of the
filter;
and
Figure 4 shows a cross-sectional side view of a third embodiment of the
filter.
9o Referring to Figure 1, there is shown a smoking article 2, in the form of a
cigarette, which includes a filter 4 in accordance with the invention. Even
though the Figures show the smoking article 2 as a cigarette, it should be
appreciated that the smoking article 2 may take other forms, such as cigars
and
cigarillos etc, which may also include the filter 4 according to the
invention.
Referring to Figure 1, the smoking article 2 comprises a generally cylindrical
paper-wrapped rod 6 of smokeable material, such as tobacco, which is co-
axially
attached to the filter 4 by tipping paper 8, which is glued around one end of
the
rod 6 and the filter 4.
Referring to Figure 2, there is shown a first embodiment of the filter 4
attached
to the rod of tobacco 6. In this embodiment, the filter 4 is made up of a
single,
filter element 12 about 27mm in length, which consists of a continuous plug of
filter material 20 (for example, cellulose acetate) having a diameter of 9mm.
The
filter element 12 has first and second generally circular end faces 22, 24,
and a
circumferential or longitudinally extending side surface 26 substantially
perpendicular to the first and second end faces 22, 24. As shown in Figure 2,
a
thin tobacco thread 10 having a diameter of 0.8mm extends between the two end
faces 22, 24 through the plug of filter material 20. The thread is
substantially
parallel with the longitudinally extending surface 26, and extends
substantially
3o through the centre of the plug of filter material 20, thereby forming a
core.
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The thread of tobacco 10 is prepared either from tobacco fibres and/or tobacco
sheet, using technology known in the art, and using materials which may be
obtained from LTR industries, France, or from Deli-HTL, Holland. For
example, a wet slurry of tobacco dust, cut tobacco stems, and a binding agent
is
initially prepared, and then rolled out on to a stainless steel conveyer to
form a
wet tobacco sheet. The conveyer is fed into an oven which heats the slurry
until
it dries, thereby forming a band cast reconstituted tobacco sheet. For
example,
suitable heating may be at about 70-100 C for about 6-8 minutes. The tobacco
sheet is then cut to the appropriate dimensions (0.8mm diameter) by cutters to
produce thread 10, which may then be fed on to a reel, ready for use.
Flavourant
may be added to the sheet, before being formed into the thread 10. Another
example for preparing the tobacco thread 10 is by tightly twisting tobacco
plant
fibres in a similar method to that used for preparing cotton.
The resultant thread 10 is approximately 0.8mm in diameter, which is then
introduced into the centre of the filter material 20. One method of
introducing
the tobacco thread 10 in to the plug of filter material 20 in the manufacture
of
the filter element 12 as follows. The method involves entraining the tobacco
thread 10 through the lumen of a guide tube having a diameter of about 1.5mm.
Simultaneously, a supply of fibrous filter material 20 (e.g. cellulose
acetate) is
passed through a series of blooming rollers so that it is de-crimped. A tow of
de-crimped filter material 20 is then formed around the thread 10 as it exits
the
guide tube, to thereby form a continuous rod of filter material 20 enclosing
the
thread 10. The rod may then be cut up in to sections to produce the completed
filter element 12 as shown in Figure 2. The length of the filter element 12
will
depend on the type of filter 4 required. For example, a standard cigarette
filter 4
is about 27mm in length. In the embodiment shown in Figure 2, the whole
27mm length of the filter 4 consists of the filter element 12, such that the
thread
10 extends all the way along. However, Figures 3 and 4 illustrate other
embodiments, in which the filter 4 comprises a shorter section of the filter
element 12 containing the thread 10 in combination with other sections, as
described below.
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Referring to Figure 3, there is a shown a second embodiment of the filter 4
attached to the rod of tobacco 6. The filter 4 comprises a plurality of
different
discrete filter elements 12, 14, 16, each of which may have a different
material
composition. In this embodiment, the filter 4 includes three different filter
elements 12, 14, 16. Each filter element 12, 14, 16 is generally cylindrical
in
shape having substantially equivalent diameters. Each filter element 12, 12,
16 is
wrapped by a layer of thin sheet material in the form of a wrapper known as
plugwrap (not shown), which may be formed of conventional paper materials.
9o The filter element 16 that is farthest from the tobacco rod 6 (and which
will be
closest to the smoker's mouth when in use) comprises a generally cylindrical
tow
of filter material 20, such as cellulose acetate. The filter material 20
provides a
filter through which smoke may pass as a smoker inhales on the cigarette. The
filter element 12 that is disposed adjacent element 16 contains a continuous
plug
of filter material 20 having the tobacco thread 10 extending substantially
longitudinally therethrough. This filter element 12 is similar to that shown
in
Figure 1, except that it does not extend along the entire length of the filter
4.
The third filter element 14 that is disposed between the filter element 12
containing the tobacco thread 10 and the tobacco rod 6 comprises a plug of
filter
material 20, in which an adsorbent, such as activated carbon 18, has been
dispersed. The activated carbon 18 may be in the form of granular activated
carbon 18, which is distributed evenly throughout the volume of the plug of
cellulose acetate 20 in a "Dalmatian" style, as is known in the art, and as
shown
in Figure 3. Alternatively, the activated carbon 18 may be sprinkled onto a
sticky
exterior surface 26 of the plug of cellulose acetate 20, or adhered to the
inner
surface of plugwrap surrounding the cellulose acetate, or adhered to a cotton
thread surrounded by the plug of cellulose acetate 20 (not shown). The
activated
carbon 18 could also be held in a cavity surrounded by the plug of cellulose
3o acetate 20. The activated carbon 18 is provided to improve the
characteristics of
the smoke that is inhaled by removing toxic chemicals.
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Referring to Figure 4, there is a shown a third embodiment of the filter 4
attached to the tobacco rod 6. In this embodiment, the filter 4 includes the
same
three filter elements 12, 14, 16 as in the second embodiment, as described
above,
except that the order of the elements has been changed. As shown in Figure 4,
the filter element 16 that is farthest from the tobacco rod 6 comprises filter
material 20, such as cellulose acetate, as in the second embodiment. However,
in
the third embodiment, the filter element 12 that is disposed adjacent element
16
contains a plug of filter material 20, in which particles of activated carbon
18
have been dispersed. Finally, the third filter element 12 disposed between
element 14 and the rod of tobacco 6 contains a continuous plug of filter
material
through which the tobacco thread 10 extends. Accordingly, the positions of
filter elements 12, 14 have been swapped in the second and third embodiments.
As shown in Figures 3 and 4, the filter elements 12, 14, 16 are arranged
15 longitudinally of one another with the end face 22, 24 of each filter
element 12,
14, 16 abutting the next. Although the three filter elements 12, 14, 16 are
shown
in Figures 3 and 4 as being substantially equal in length, it will be
appreciated
that they could have different lengths. For example, in Figures 3 and 4, the
filter
element 12 containing the tobacco thread 10 could be 12mm in length, and the
20 other elements 14, 16 could be 7.5mm each, such that the total length of
the
filter 4 is 27mm. In addition, it will be appreciated that the filter 4 may
comprise
only the two filter elements. For example, the filter 4 may comprise the
filter
element 12 containing the tobacco thread 10 (about 15mm long) and the filter
element 16 containing only filter material 20 (about 12mm long), in either
order.
Alternatively, the filter 4 may comprise the filter element 12 containing the
tobacco thread 10 and the filter element 14 containing activated carbon 18, in
either order.
Also, the filter 4 may comprise more than three filter elements 12, 14, 16.
For
3o example, the filter 4 may comprise first and second filter elements 16
composed
of cellulose acetate, a third filter element 14 comprising cellulose acetate
and
activated carbon 18, and a fourth filter element 12 comprising the
longitudinal
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tobacco thread 10 core, as described above. It will be appreciated that the
various filter elements 12, 14, 16 may be arranged in the filter 4 in a
variety of
alternative orders. However, in each embodiment, at least one filter element
12
containing the tobacco thread 10 is included in the filter 4.
Referring to Figure 1 once again, the filter 4 is located at a mouth-end of
the
smoking article 2 such that a gaseous flow, comprising smoke drawn from the
rod 6 of smokeable material, moves through the filter 4 before entering the
mouth of a smoker. The tobacco thread 10 is located in one or more filter
elements 12, and extends longitudinally between the end faces 22, 24 of a plug
of
filter material 20, as described in relation to Figure 2. In this way, the
tobacco
thread 10 is disposed in close proximity with the path of the gaseous flow as
it
moves through the filter 4, and is therefore able to affect various
characteristics
of the gaseous flow before the flow reaches the smoker's mouth.
The tobacco thread 10 may, for example, affect the overall properties of the
gaseous flow such that the taste and flavour of the gaseous flow are improved.
One application of the tobacco thread 10 is to replace a degree of the taste
and
flavour characteristics of the gaseous flow which may be lost as the gaseous
flow
moves through the filter material 20, or the activated carbon 18, which is
known
to affect the taste and flavour of tobacco smoke. The inventors have
surprisingly found that the arrangement of the thin thread of tobacco 10
extending longitudinally through the plug of filter material 20 improves the
flavour of the smoke without compromising the flow characteristics of the
smoke.
The invention also includes further modifications and variations falling
within
the scope of the claims.
