U.S. patent application number 13/696296 was filed with the patent office on 2013-05-30 for filter additive.
This patent application is currently assigned to BRITISH AMERICAN TOBACCO (INVESTMENTS) LIMITED. The applicant listed for this patent is David Rushforth, John Sampson. Invention is credited to David Rushforth, John Sampson.
Application Number | 20130137561 13/696296 |
Document ID | / |
Family ID | 42334676 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130137561 |
Kind Code |
A1 |
Sampson; John ; et
al. |
May 30, 2013 |
Filter Additive
Abstract
The present invention relates to a method of producing a filter
element for inclusion in a smoking article, the method comprising
applying an additive to filter material, the additive being solid
at room temperature and the method involving heating the additive
so that it melts.
Inventors: |
Sampson; John; (London,
GB) ; Rushforth; David; (London, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sampson; John
Rushforth; David |
London
London |
|
GB
GB |
|
|
Assignee: |
BRITISH AMERICAN TOBACCO
(INVESTMENTS) LIMITED
London
GB
|
Family ID: |
42334676 |
Appl. No.: |
13/696296 |
Filed: |
May 11, 2011 |
PCT Filed: |
May 11, 2011 |
PCT NO: |
PCT/GB2011/050899 |
371 Date: |
February 12, 2013 |
Current U.S.
Class: |
493/39 |
Current CPC
Class: |
A24D 3/0212 20130101;
A24D 3/048 20130101; A24D 3/02 20130101 |
Class at
Publication: |
493/39 |
International
Class: |
A24D 3/02 20060101
A24D003/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 2010 |
GB |
1007946.5 |
Claims
1. A method for making a smoking article filter element comprising
sheet material and an additive, wherein the method comprises the
steps of: i) applying an additive which is solid at room
temperature to the filter material; ii) heating the additive so as
to melt it; and iii) forming the filter material and additive into
a filter element, wherein the steps of the method may be carried
out in any order.
2. A method as claimed in claim 1, wherein the additive material is
applied to the filter material before formation of the filter
element and subsequent heating of the additive.
3. A method as claimed in claim 1, wherein the additive is heated
and applied to the filter material as a liquid, before the
formation of the filter element.
4. A method according to any one of the preceding claims, wherein
the additive comprises a high molecular weight polyethylene glycol
which is solid at room temperature.
5. A method according to claim 4, wherein the polyethylene glycol
is PEG 1000.
6. A method according to any one of the preceding claims, wherein
the additive is included in the filter element in an amount of up
to about 50% by weight of the filter element.
7. A method according to any one of the preceding claims, wherein
the filter material is a non-woven sheet material or paper.
8. A method according to any one of claims 1-6, wherein the filter
material is a fibrous tow.
9. A method according to any one of the preceding claims, wherein
the filter element further comprises at least one adsorbent
material.
10. A filter element for a smoking article, comprising filter
material and an additive which is solid at room temperature,
wherein the filter element is obtained or obtainable by a method as
claimed in any one of the preceding claims.
11. A filter for a smoking article, comprising a filter element as
claimed in claim 10.
12. A smoking article comprising a filter element as claimed in
claim 10 and/or a filter as claimed in claim 11, and a rod of
smokeable filler material.
13. A smoking article according to claim 12, wherein the article is
a cigarette.
Description
[0001] The invention relates to methods for making filter elements
and filters for smoking articles, the filter elements and filters
comprising an additive material. In particular, the invention
relates to methods of incorporating an additive which is solid at
room temperature into filter material, the method comprising the
step of melting the additive material.
[0002] A wide variety of materials have been used as filter
materials for tobacco smoke. The most commonly used filter material
is cellulose acetate tow. However, whilst cellulose acetate has an
excellent capacity to filter tobacco smoke, it has the drawback
that it is slower to degrade than other materials and can therefore
be disadvantageous environmentally.
[0003] Filter materials made from non-woven sheet material and
paper are known. Suitable sheet materials include polyvinyl
alcohol, reconstituted tobacco, starch, and polylactic acid. These
materials are much more readily degradable than cellulose acetate
tow, however, they have drawbacks. In particular, in order to
attain the desired structural rigidity when constructing a filter
element from non-woven sheet materials and paper, the filter
material is generally densely packed and this means that these
filter elements have quite different properties to those made of
cellulose acetate. They exhibit a greater resistance to the flow of
smoke, resulting in a pressure drop which is higher than that of a
conventional cellulose acetate (CA) filter, requiring the user to
draw harder on the smoking article. Perhaps more significantly, the
smoke drawn through such filter material has been found to have
different taste characteristics compared to the smoke drawn through
conventional cellulose acetate filter material. What is more,
filter elements comprising non-woven sheet materials or paper as
the filter material have been shown to exhibit significantly less
selective removal of semi-volatile compounds than conventional
cellulose acetate tow filter materials.
[0004] It is known to use additives such as triacetin (glycerin
triacetate), TEC (triethyl citrate) and PEG 400 (low molecular
weight polyethylene glycol) in cellulose acetate filters. These
additives function as plasticizers and they are generally used in
cellulose acetate filters to give the filter rods sufficient
hardness for cigarette manufacture and use. Some plasticizers have
the additional advantage of providing cellulose acetate tow with an
improved capacity to selectively remove semi-volatile compounds
such as phenol, o-cresol, p-cresol and m-cresol from tobacco
smoke.
[0005] These plasticizers are in liquid form at room temperature
and they are sprayed on to cellulose acetate tow. The plasticizer
coats the individual fibres within the tow and, with time, they
bind or fuse adjacent fibres together at their points of contact,
thereby increasing the hardness or rigidity of the filter material,
to give the core of the filter the desired structural strength. The
mode of action of the plasticizers does, however, mean that there
is an upper limit to the amount that may be incorporated into
cellulose acetate tow filter material. When above about 7% of
plasticizer by weight of the filter is included, the plasticizer
starts to have a detrimental effect on the cellulose acetate tow,
forming holes which compromises its filtration properties.
[0006] Whilst inclusion of plasticizers such as triacetin, TEC or
PEG 400 in CA filters is relatively common, their inclusion in
non-woven sheet and paper filter materials is less attractive.
Firstly, the plasticizers are used in CA filters to bind fibres and
the plasticizer would clearly not have this advantageous effect
when added to non-woven sheet material or paper (in which the
fibres are already bound within the sheet structure). Secondly,
these commonly used plasticizers are liquids and their application
to non-woven sheet and paper filter materials will be limited as
they will cause these materials to become soggy and to lose their
structural integrity. Paper, the most commonly used sheet filter
material, may start to disintegrate when moist, and will therefore
have a reduced acceptability to the user. Furthermore, many sheet
materials, including polyvinyl alcohol and polylactic acid, are
soluble and therefore the addition of aqueous additives may result
in the partial dissolution of the material.
[0007] It is therefore an object of the invention to provide a
method of constructing a filter element which is more readily
degradable than filter elements comprising a conventional cellulose
acetate tow as the filter material. Preferably, the method will
also result in a filter element which exhibits an improved capacity
to selectively remove semi-volatile compounds and which provides
smoke having similar taste characteristics to that provided by
conventional cellulose acetate filters.
SUMMARY OF THE INVENTION
[0008] According to a first aspect of the present invention, a
method for making a smoking article filter element is provided. The
method comprises the steps of: [0009] i) applying an additive which
is solid at room temperature to the filter material; [0010] ii)
heating the additive so as to melt it; and [0011] iii) forming the
filter material and additive into a filter element.
[0012] The steps of the method may be carried out in any order,
although in some embodiments, step i) is preferably carried out
before step iii).
[0013] According to a second aspect of the present invention, a
filter element for a smoking article is provided. The filter
element comprises filter material and an additive which is solid at
room temperature, the filter element being obtained or obtainable
by the method according to the first aspect of the present
invention.
[0014] According to a third aspect of the present invention, a
filter for a smoking article is provided, comprising a filter
element according to the second aspect.
[0015] According to a fourth aspect of the present invention, there
is provided a smoking article comprising a filter element according
to the second aspect and/or a filter according to the third aspect,
attached to a rod of smokeable filler material. The smokeable
filler material may comprise tobacco and the smoking article may be
a cigarette.
[0016] 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.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention relates to a method of producing a
filter element for inclusion in a smoking article, the method
comprising applying an additive to filter material, the additive
being solid at room temperature and the method involving heating
the additive so that it melts.
[0018] In one embodiment of the invention, the additive is applied
to the filter material in solid form, for example in the form of a
powder, prior to formation of the filter rod. The formed filter rod
may then be heated to melt the additive whilst it remains in
contact with the filter material. When the additive material
subsequently cools and re-solidifies, it provides the filter
material and the filter element formed with one or more of:
stability and rigidity; improved smoke taste characteristics; and
improved selective removal of semi-volatile compounds.
[0019] In an alternative embodiment of the invention, the additive
is melted and applied to the filter material in molten or liquid
form, prior to formation of the filter rod. When the additive
material subsequently cools and re-solidifies, it provides the
filter material and the filter element formed with one or more of:
stability and rigidity; improved smoke taste characteristics; and
improved selective removal of semi-volatile compounds.
[0020] The methods according to the present invention may be used
to add an additive to any type of filter material, including
fibrous filter material or tows, such as conventional cellulose
acetate tow which is currently widely used in smoking article
filters. However, the method is considered to be particularly
effective when it is used to add an additive to alternative filter
materials, such as those constructed from a sheet material, for
example non-woven sheet materials or paper.
[0021] Paper filter material usually comprises gathered, pleated,
crimped, crepe or even shredded paper. Paper filter materials tend
to have a low air permeability, exhibit a basic pH, and can be
gathered or formed easily to form the filter element. A preferred
filter material for filter elements of the present invention is a
gathered or pleated paper. Examples of suitable papers are
Puracel.TM. and Myria.TM. papers (Filtrona plc, United
Kingdom).
[0022] Other, non-woven sheet materials may be used as filter
materials. Non-woven materials are broadly defined as sheet or web
structures bonded together by entangling fibres or filaments
mechanically, thermally or chemically, or by a combination of two
or more of these. They tend to be flat, porous sheets that are made
directly from separate fibers. They are not made by weaving or
knitting and do not require converting the fibers to yarn. The
non-woven sheet materials used in the present invention are
preferably ones which are readily biodegradable. Examples of
materials include polyvinyl alcohol (PVOH), polylactic acid or
polylactide (PLA), poly(.epsilon.-caprolactone) (PCL), poly(1-4
butanediol succunate) (PBS) and poly(butylene
adipate-co-terephthalate) (PBAT). Other suitable filter materials
include starch fibres and calcium alginate.
[0023] Non-woven sheet materials and paper are more readily
biodegradable than cellulose acetate tow. However, they currently
have drawbacks when used as filter materials. In order to attain
the desired structural rigidity when constructing a filter element
from non-woven sheet materials and paper, the filter material must
be very densely packed and this means that these filter elements
have quite different properties to those made of cellulose acetate.
They exhibit a greater resistance to the flow of smoke, resulting
in a pressure drop which is higher than that of a conventional
cellulose acetate filter, requiring the user to draw harder on the
smoking article.
[0024] The sheet material used in the method of the invention may
comprise paper, polyvinyl alcohol, reconstituted tobacco, starch,
or polylactic acid. Preferably the sheet filter material is
paper.
[0025] Preferred non-woven sheet materials have a thickness greater
than about 0.05 mm, preferably from about 0.06 mm to about 0.08 mm.
The paper filter materials may comprise paper having a basis weight
of about 15 g/m.sup.2 to about 40 g/m.sup.2, preferably about 20
g/m.sup.2 to about 35 g/m.sup.2.
[0026] The sheet material used in the method of the invention may
additionally or alternatively comprise polyvinyl alcohol (PVOH).
PVOH is unique in being the only biodegradable, carbon-carbon
backbone polymer that can completely biodegrade to small molecules,
e.g., carbon dioxide and water.
[0027] The method may comprise the use of the sheet material
polylactic acid. The lactate from which PLA is produced can be
derived from the fermentation of agricultural by-products.
[0028] However, because of the hygroscopicity of PVOH and PLA,
prior art attempts to process such materials have resulted in
filter rods which are too soft to be efficiently handled in high
speed cigarette manufacturing machines. Furthermore, cigarette
filter elements formed from PVOH and PLA have failed to provide a
sufficiently stable porous matrix to permit proper draw
characteristics and avoid collapse in use. Using the method of the
present invention to apply additive, the qualities of these sheet
materials may be modified to make them suitable for use in filter
elements.
[0029] In contrast to the use of additives which are liquid at room
temperature (such as the plasticisers frequently used in
conventional cellulose acetate filters, including low molecular
weight PEG, triacetin and TEC), an additive which is solid at room
temperature may provide firmness and rigidity to the filter without
damaging the filter material by making it soggy.
[0030] Indeed, rather than weakening a non-woven sheet or paper
filter material, the method of the present invention uses a solid
additive which has been melted, but which re-solidifies at room
temperature and bonds parts of the filter material together.
Therefore, the additive has the benefit that it can actually
increase the structural integrity and rigidity of the filter
material. In the case of sheet filter materials, addition of a
solid additive by a method according to the present invention may
make it possible to use less of the filter material in the filter
element. This provides further flexibility when forming the filter
element with regard to the amount of filter material required to
achieve the desired hardness and rigidity. This in turn would allow
the manufacturer to adjust the pressure drop of the filter element.
This would allow a filter element according to the present
invention to be designed having properties which closely resemble
those of conventional CA filter elements.
[0031] Thus, the addition of a solid additive to the filter
material by the methods according to the present invention can
eliminate the shortcomings that are currently associated with the
use of sheet filter materials, by improving the rigidity of the
filter, improving the taste of the smoke, and increasing the
selective removal of semi-volatile compounds. Furthermore, the
combination of filter material and solid additive may provide
vastly improved disintegration, dispersion and/or biodegradability
of the filter element.
[0032] The methods of the invention allow the properties of
non-woven sheet and paper filter materials to be fine-tuned, so
that the performance of the filter element can more closely
resemble that of a cellulose acetate filter element. These
additives also give the use of sheet filter material much greater
flexibility, widening the range of its applicability whilst
retaining the beneficial biodegradable properties.
[0033] In one embodiment of the invention, the additive comprises a
high molecular weight polyethylene glycol which is solid at room
temperature. Suitable PEGs include PEG 600 and higher, and
preferably PEG 1000 and higher.
[0034] High molecular weight polyethylene glycol has the additional
advantage of providing selective removal of semi-volatile
compounds. This selective removal of semi-volatile compounds
provided by the addition of the PEG to the filter element is
proportional to the amount of PEG included. The methods of the
present invention, which involve the use a PEG which is solid at
room temperature (in contrast to the PEG previously used in
filters) provide flexibility which allows the addition of greater
amounts of PEG than would be possible if using a liquid PEG.
[0035] This means that the ability of the filter element to
selectively remove semi-volatile compounds may easily be adjusted
to a desirable level. This is in contrast to the situation where
low molecular weight PEG is added to cellulose acetate filters as a
plasticizer. Cellulose acetate filters are generally disclosed as
including less than 10% plasticizer because including higher levels
of plasticizer than this has a detrimental effect on the cellulose
acetate tow, causing holes to be formed. Consequently, the amount
of plasticizer available to provide selective removal of
semi-volatile compounds in cellulose acetate filters is
limited.
[0036] According to the method of the invention, PEG may be
included in the filter material of the filter element in an amount
of up to about 30%, preferably up to about 20%, and more preferably
about 5-10% by weight of the filter element.
[0037] As PEG is water-soluble, its inclusion in the filter
elements should not adversely affect the biodegradation of the
product. Indeed, it has been surprisingly found that the addition
of PEG to a filter element comprising a non-woven sheet material or
paper as the filter material actually enhances biodegradation.
[0038] A study was conducted to assess the effect of the use of a
paper filter material and additives on biodegradability.
Degradation of cigarette butts under environmental conditions was
assessed. The samples used included a filter with Puracel.TM. (7
mg) with no additive and a filter with Puracel.TM. with 7% PEG 400.
The results show that the inclusion of the PEG as an additive
significantly increased the rate of biodegradation of the butts on
a grass surface. It is speculated that this may have been due to
the presence of microorganisms, insects and the like, which fed on
the butts and the presence of the PEG additive made some butts more
attractive. It is anticipated that a similar effect will be
observed upon use of a high molecular weight PEG as an
additive.
[0039] Other additives which may be used in the methods of the
present invention include high molecular weight methoxypolyethylene
glycols (MPEGs), such as MPEG 750, 1000, 2000, 3000 and 5000; and
waxes which are solid at room temperature, including beeswax,
carnauba, shellac, castor wax, paraffin and various synthetic
waxes.
[0040] If desired, the method can further comprise the
incorporation into the sheet filter material of further additives
such as tobacco extracts, glycerine, menthol, carbon fibres, carbon
particles, and the like.
[0041] A further advantage of the method of the invention is that
filter elements to which additive has been applied using the
claimed method are more stable to the subsequent addition of
additives, including liquid additives. Other additives, including
liquid additives, which would otherwise have been difficult to
apply to sheet material without making it soggy, can be added to
the filter rod to adjust the properties of the filter as required,
or provide further qualities to the filter element, such as
flavourants for enhanced flavour.
[0042] Methods according to the present invention encompass
different ways of applying the additive to the filter material.
[0043] In one embodiment, the method involves applying the additive
to the filter material in liquid form. In order to do this, the
additive must be heated and is sprayed or otherwise applied to the
filter material before the filter material is formed into the
filter rod or core of the filter element.
[0044] This embodiment is attractive because it necessitates
relatively little modification of conventional filter-making
machinery. The only real change is the provision of means for
heating the additive so that it is in molten form and may be
applied to the filter material in that form. The application of the
heat is relatively easy to control and monitor. Also, the
application of heat is primarily just to the additive and so other
components of the filter element do not need to be exposed to
localised heat.
[0045] This method is applicable to both fibrous tow filter
materials as well as to non-woven sheet materials and paper.
Although such sheet materials are being fed under some tension, the
application of the liquid additive does not weaken the sheet
structure sufficiently to cause a problem.
[0046] In an alternative embodiment, the method involves applying
the additive to the filter material in solid form, for example in
the form of a powder, before the filter material is formed into the
filter rod or core of the filter element. Once formed, the filter
rod is heated to melt the additive. The additive melts and
subsequently re-solidifies, bonding the filter material without
making it soggy.
[0047] This method allows the additive to be applied to the filter
material in a controlled and uniform manner, and with minimal
wastage of additive material. It also avoids any potential
disadvantages associated with applying a liquid to the filter
material. For example, in the case of sheet filter materials, this
embodiment avoids the potential weakening of the sheet structure by
applying a liquid.
[0048] Where the solid additive is being applied to a sheet
material, such as the non-woven sheet materials and papers
discussed herein, steps will need to be taken to ensure that the
solid additive remains in contact with the sheet filter material
whilst the sheet is being fashioned into a filter rod. This may
require the application of some adhesive or special orientation of
the sheet material.
[0049] Filter elements comprising sheet materials are generally
manufactured using a process which comprises the steps of crimping
the sheet material and then gathering the sheet material to form a
cylindrical filter rod. The additive may be added prior to or
during the crimping process, or may be added to the sheet material
after it has been crimped. The additive may even be added to the
crimped material as it is gathered to form the filter rod, with the
effect that it is immediately contained within the rod and does not
need to be adhered.
[0050] The additive may be adhered to the filter material using any
suitable adhesive, for example, using liquid starch adhesives, or
EVA and PVA adhesives.
[0051] The solid additive may be applied to sheet filter material
as a powder or in larger pieces, such as in the form of flakes or
pellets.
[0052] The additive may be applied to the filter material by any
suitable method that is known to the skilled person. For example,
powdered additive may be sprayed on to the filter material, or it
may be applied by an applicator which may or may not be in direct
physical contact with the filter material. The additive may be
loosely applied to the filter material, for example by being
sprayed or sprinkled, or may be applied using a degree of force,
such as by being pressed or smeared on to the filter material.
[0053] In a particular embodiment, the filter material is formed
with the solid additive embedded in or on it. Applying the additive
which is solid at room temperature to the filter material in this
way can simplify the methods of the present invention. Once the
filter material has been formed into the filter rod, the rod may be
heated to melt the additive, and then allowed to re-solidify.
[0054] It is known to add various materials in or on sheet
materials such as non-woven sheet materials and paper. For example,
the additive may be applied to the sheet material during its
manufacture or as part of a post-manufacture processing step. In
this way, the additive may be incorporated within the sheet, or as
a coating on one or both sides of the sheet material. The additive
may be uniformly present within or on the surface of the sheet, or
may be present in discreet areas, such as in patches or strips on
the sheet material.
[0055] Fibrous filter material may also be prepared with particles
of solid additive material dispersed throughout the fibres. Such
particles may need to be adhered to the fibres. Alternatively, they
may become trapped between adjacent fibres if the fibrous material
is dense enough.
[0056] Where the additive is applied to the filter material in
liquid form, the heating step of the method of the invention
involves applying sufficient heat to the additive to ensure that
the additive is molten to the extent that it has a viscosity
suitable for the mode of application chosen. The molten or liquid
additive may be sprayed or printed, or the filter material may be
submerged in the liquid additive.
[0057] According to one embodiment, a system for applying molten or
liquid additive to filter material comprises a heated chamber in
which the additive is maintained in liquid form, a pump, and a hose
with one or more nozzles configured to spray droplets onto the
filter material prior to formation of the filter.
[0058] A number of application systems are known which are suitable
for applying molten or liquid additive to filter material. Such
systems are available, for example, from SPI Developments, C. B.
Kaymich & Co. Ltd, or Kohl Maschinenbau GmbH.
[0059] Where the additive is to be melted after the filter material
has been formed into a rod or core, sufficient heat needs to be
applied to ensure that all of the additive, which is dispersed
throughout the rod, is melted.
[0060] The application of heat to the formed filter rod must be
carried out with care, as it may have a detrimental effect on other
components of the filter rod, including the filter material and any
wrapper (which is likely to be paper and could be singed or
scorched by exposure to high temperatures).
[0061] Obviously, the temperature that the filter rod must be
heated to, and the duration of heating, is dependent upon the
melting point of the additive. A preferred additive, PEG 1000, has
a melting point of around 37.degree. C., and therefore in this
case, the filter rod is heated to a temperature exceeding
37.degree. C. The filter rod may be heated to a temperature
exceeding 40.degree. C., preferably exceeding 45.degree. C., and
most preferably exceeding 50.degree. C. In addition, the heat needs
to be applied for a period sufficient to ensure that the whole rod
is heated and not just the outer areas.
[0062] Heat may be applied using any suitable means. For example,
the filter rod or filter element may be brought into close
proximity with a heating element. Alternatively or additionally,
the filter rod or filter element may be heated by means of a
current of hot gas, such as hot air or steam, or via the
application of radiation, such as microwave radiation.
[0063] Heat may be applied to the filter rod as soon as it is
formed. In other words, heating of the filter rod may occur at some
stage between formation of the filter rod at the garniture and the
cut-off, where the filter rod is separated into sections. Heating
of the rod will generally be for a very brief period, such as less
than 1 second, due to the linear motion of the rod through the
machine. Clearly, since filter rods are currently formed without a
heating process, then concomitant forming and heating of the filter
rod may require expensive modification of the current
apparatus.
[0064] For this reason, the filter rod is preferably heated at a
later stage, and this may be achieved using a heater which is
essentially separate from the apparatus involved in forming the
filter rod. The heating is preferably carried out in a separate
conditioning step, where lengths of filter rod are kept at an
elevated temperature for an extended period of time to ensure that
all of the additive is melted and bonds to the filter material.
[0065] The method of the invention may further comprise wrapping
the filter rod in a suitable wrapper such as a plugwrap. In this
case the heat may be applied before the filter rod is wrapped.
Alternatively, the filter rod may be wrapped and then heated.
[0066] According to some embodiments, the assembled filter is
heated to melt the additive, although this approach can be
complicated by the insulating properties of the filter material. In
addition the speed of filter manufacture means that the time
available for heating the filter is limited. Having said that,
heating of the assembled filter may be achieved in various ways.
For example, the filter rod may be exposed to heat by conductance,
such as on a heated drum in the presence of hot air. Alternatively,
trays of filter rods (such as 4,000 filters per tray) may be passed
through a heated tunnel or similar arrangement, in the presence of
hot air. The filter trays may alternatively be heated by the
application of radiation such as microwave radiation. The methods
of the present invention may further comprise a step of
incorporating particulate material into the filter element.
Suitable particulate material includes sorbents (e.g. selected from
activated carbon, charcoal, silica gel, sepiolite, alumina, ion
exchange material etc.), pH modifiers (e.g. alkaline materials such
as Na.sub.2CO.sub.3, acidic materials), flavourants, other solid
additives and mixtures thereof.
[0067] Advantageously, the particulate material may be selected
from a group of relatively high surface area materials capable of
adsorbing smoke constituents without a high degree of specificity.
Suitable general adsorbents can be selected from the group
consisting of carbon, activated carbon, activated charcoal,
activated coconut carbon, activated coal-based carbon or charcoal,
zeolite, silica gel, meerschaum, aluminium oxide (activated or
not), carbonaceous resin or combinations thereof.
[0068] One type of particulate material which may be used in the
method of the invention is carbon, for instance activated carbon,
or charcoal or other carbonaceous absorbent material. The preferred
type of activated carbon is activated coconut carbon.
[0069] The particulate material may be incorporated into the filter
element in such a way that it is interspersed throughout the filter
element, or it may be interspersed in some parts (but not all) of
the filter element. The particulate material may be interspersed
over the full longitudinal length of the core. Alternatively, the
particulate material may be interspersed from one end of the core
to a section that is short of the other end. Alternatively, the
particulate material may be present in discrete areas that need not
extend from--or be present at--any end of the core.
[0070] Different areas may have different loadings of particulate
material and/or different types of particulate material.
[0071] The methods of the present invention may further comprise
wrapping the filter element in a suitable wrapper.
[0072] The wrapper of the filter element is preferably a paper
wrapper, and most preferably comprises conventional plugwrap, such
as plugwrap having a basis weight of between about 20 g/m.sup.2 and
about 35 g/m.sup.2, preferably about 27 g/m.sup.2. The plugwrap may
be porous or non-porous.
[0073] The method may comprise the use of a wrapper which includes
a particulate material adhered to one or more portions of its
surface. Preferably, the particulate material is adhered to two or
more portions of the wrapper, the portions being circumferentially
spaced from one another, with at least one of the portions
extending over the full longitudinal length of the wrapper.
[0074] The smoking article filter element produced according to the
method of the present invention may be incorporated into a smoking
article filter.
[0075] The smoking article filter may comprise a single filter
element of the method of the invention. Alternatively, the smoking
article filter may include two or more filter elements produced
according to the method of the invention. In other words, the
filter element may be part of a composite (or multi-component)
filter. Suitably the filter elements of the composite filter are
arranged longitudinally of one another with the end of each filter
element abutting the next. The composite filter may have 2, 3, 4 or
more distinct or discrete sections. In one embodiment the filter is
a triple-filter with three sections. In another embodiment the
filter is a dual-filter with two sections.
[0076] The filter sections of the composite filter may be
identical, or alternatively, one or more of the sections may have a
composition which is different to that of the other section or
sections. For example, in some embodiments, one or more of the
sections may optionally comprise: (i) cellulose acetate filter
material; (ii) a biodegradable filter material, such as crepe,
crimped or gathered paper material; (iii) one or more additives,
such as adsorbent or flavouring materials, which may be
encapsulated; and/or, (iv) a cavity, which may comprise granular
material such as adsorbent material.
[0077] The smoking article filter element produced according to the
method of the present invention may be incorporated into a smoking
article. The filter element may be in the form of a smoking article
filter as described above.
[0078] The filter element and/or filter comprising the filter
element may be attached to a wrapped smokeable filler material rod
(i.e. a wrapped tobacco rod, for instance) by conventional tipping
overwrap to form the smoking article, which may be a cigarette.
[0079] Suitably, the smokeable filler material may be tobacco
material or a tobacco substitute material. Preferably the smokeable
material is a tobacco material. Suitably the tobacco material
comprises one or more of stem, lamina, and tobacco dust. It is
preferred that the tobacco material comprises one or more of the
following types: Virginia or flue-cured tobacco, Burley tobacco,
Oriental tobacco, reconstituted tobacco. It is much by preference
that the smokeable material comprises a blend of tobacco
material.
[0080] The smokeable filler material may also comprise one or more
of the following: burn additive, ash improver, inorganic filler
material, organic filler, aerosol generating means, binder,
flavouring and/or colouring agents.
[0081] The tipping overwrap may be ventilating or non-ventilating
overwrap.
[0082] Various modifications and variations of the described
methods and system of the present invention will be apparent to
those skilled in the art without departing from the scope of the
present invention. Although the present invention has been
described in connection with specific preferred embodiments, it
should be understood that the invention as claimed should not be
unduly limited to such specific embodiments. Indeed, various
modifications of the described modes for carrying out the invention
which are obvious to those skilled in the art are intended to be
within the scope of the following claims.
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