Note: Descriptions are shown in the official language in which they were submitted.
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Enhancing the Disintegration and/or Degradation of a Smoking Article
Description
The invention relates to enhancing the disintegration and/or degradation of
used
smoking articles, and particularly, but not exclusively, to enhancing the
disintegration and/or degradation of the filter of such smoking articles.
A problem with currently available tobacco smoke filters, particularly
cigarette
filters, is that they can be difficult to dispose of after use.
During smoking most of the tobacco rod and its circumscribing paper wrapper
are
converted to gases and ash in an incineration process. The remaining
components
of the spent smoking article include a small portion of ash, part of the
original
tobacco rod and wrapper, and the filter which is made up of the filter plug,
plugwrap, and tipping paper wrapped about the tobacco rod and filter. There
are
also adhesives present that secure these components together. Spent smoking
articles are generally completely dissociated into their individual
constituent parts
within a relatively short period of time when exposed to moisture, and/or
mechanical abrasion. The individual components of the spent smoking articles
are
thus subsequently able to disperse and degrade.
The plug of filter material, however, typically does not readily disperse or
degrade.
With limited exceptions, filters are presently formed from highly crimped
cellulose
acetate fibres bonded at their contact points using plasticizers to provide a
significant volume of interstitial space for the passage of smoke. The bonded
contact points of such filter elements degrade very slowly under normal
environmental conditions. The cellulose acetate fibres are themselves
generally
poorly biodegradable.
Despite the developments to date towards improving the biodegradability of
filter
plugs, there is interest in improved techniques for producing filters having
an
enhanced biodegradation rate. At the same time, there is also a need to retain
the
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filtration chemistry, smoke characteristics and consumer acceptability
provided by
currently available smoking article filters.
In order to produce smoking articles, including filter cigarettes, which are
more
easily disintegrated or dispersed and are more biodegradable, it is desirable
to
provide a smoking article displaying a relatively rapid dissociation of the
individual
components of the spent smoking article followed by a good rate of dispersion
and
biodegradation of the individual components. In other words, increasing the
rate of
dissociation of a spent smoking article enhances the rate of degradation by
increasing the exposure of the individual components to natural elements such
as
moisture, sunlight, mechanical abrasion, and aerobic biodegradation.
One approach that has previously been used to improve the dissociation of
spent
smoking article filters involves the incorporation of water expandable gels in
the
filter material to swell the filter upon contact with moisture and thereby
break open
the filter tipping paper to expose the filter material to the elements.
It has also been suggested to manufacture the components of a smoking article
filter, including the filtration material, the filter plugwrap, and the
tipping paper,
from a moisture disintegrative paper. The use of water soluble adhesives for
securing the filter plug and tipping paper wrappings is also known.
All of these approaches to improving the degradation of smoking article
filters
require the presence of water, such as moisture from rain, snow, dew, or
residual
moisture from those elements, for example, moist soil. However, in arid
countries
with little rainfall, such approaches ate unlikely to be effective.
A further problem is that the cellulose acetate tow commonly used as filter
material
is not readily degradable or biodegradable. Thus, despite efforts to promote
the
dissociation of the spent smoking article, the filter material itself will not
subsequently degrade. Therefore, much of the effort expended to reduce the
environmental burden of spent smoking articles or to make such spent smoking
articles more environmentally compatible has been directed to improving the
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biodegradability of the cellulose acetate fibres. Water soluble polymers have
been
used instead of triacetin which solvent bonds the cellulose acetate fibres
typically
used to make filters. Alternatively, soluble polymeric materials such as
polyvinyl
alcohol and ethylene vinyl alcohol copolymers may be used in place of
cellulose
acetate. Meanwhile, a tobacco smoke filter made of a creped paper manufactured
from a wood pulp sheet and a tobacco filter made from a regenerated cellulose
fibre
bundle are also known. Compared with a filter comprising a cellulose acetate
fibre
bundle, these filters disintegrate slightly more readily when exposed to
moisture.
While there are clearly environmentally preferable alternatives to cellulose
acetate,
degradability again generally depends on the presence of moisture, which as
mentioned previously, may be scarce in some areas.
In light of the above, at least one embodiment of the invention provides a
smoking
article having enhanced disintegration, dispersion and/or degradation. In
particular,
at least one embodiment of the invention provides a filter for a smoking
article
which is capable of degrading in the absence of environmental water.
Summary of the Invention
According to a first aspect of the invention, there is provided a filter for a
smoking
article comprising a vehicle containing a liquid for enhancing at lest one of
disintegration and degradation of the smoking article, and wherein the filter
comprises filter material which is one of soluble, swellable and dispersible
in water.
The vehicle, which can be a capsule, may be broken or otherwise actuated to
release
the liquid immediately prior to disposal of the smoking article, or may be
broken or
otherwise actuated at a later time following disposal. Generally the vehicle
is
arranged to be actuated to release the liquid after the smoking article has
been
smoked.
The vehicle can be arranged to be actuated by a longitudinal or bending force
acting
on the filter, such that, for instance, the action of 'stubbing out' the
smoking article
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acts to release the liquid. The process of actuation of the vehicle to release
the liquid
may substantially deform the filter.
The liquid may enhance the degradation of the smoking article in one or more
of the
following ways. Firstly, the various components of the smoking article may be
induced by the liquid to dissociate, resulting in their increased exposure to
the
environment and accelerated dispersion and biodegradation. Secondly, the
degradation of one or more of the components of the smoking article may be
directly enhanced by the liquid. For example, the filter may comprise a filter
material
which may be degraded by the liquid carried in the vehicle. Thus, for
instance, when
a capsule containing the liquid is broken, the liquid is released, and the
degradation
of the filter material is enhanced.
According to a third aspect of the present invention, the use of a capsule
containing
a liquid for enhancing the disintegration and/ or degradation of a smoking
article is
provided.
According to a fourth aspect of the present invention, there is provided a
method of
enhancing at least one of disintegration and degradation of a smoking article
wherein
the smoking article comprises a filter and a vehicle containing a liquid for
enhancing
at least one of disintegration and degradation of the smoking article, and
wherein the
filter comprises filter material which is one of soluble, swellable and
dispersible in
water.
Brief Description of the Drawings
For a fuller understanding of the invention, reference is made to the
accompanying
schematic drawings which each illustrate a longitudinal cross-section of an
individual
filter cigarette comprising a filter according to embodiments of the invention
(not to
scale).
Figure 1 shows a filter according to one embodiment of the present invention.
Figure 2 shows a filter according to an alternative embodiment of the present
invention.
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Detailed Description
The present invention provides a filter for use in a smoking article,
comprising a
vehicle containing a liquid capable of enhancing the disintegration,
dispersion
and/or degradation of the smoking article. The vehicle is preferably resistant
to
manipulation during use of the smoking article, and is intended to be actuated
upon
disposal of the smoking article to release the liquid contents into the
filter. The
disintegration and degradation of the filter may occur directly, for example,
by the
dissolution or dispersion of one or more of the components of the filter, such
as
the filter material, in the liquid. Alternatively, the enhancement of
degradation may
be indirect, for example, as a result of increased environmental exposure
resulting
from the accelerated dissociation of the filter by the liquid.
Figure 1 shows a smoking article 1 comprising a filter 2. The filter 2
comprises two
sections of substantially cylindrical filter plug 3, separated by a cavity 6.
The filter
plug and cavity are wrapped in a plugwrap 4. A capsule 5 comprising a liquid
is
situated within the cavity 6 of the filter 2. The smoking article further
comprises a
cylindrical rod of smokeable material 7 aligned with the filter 2 such that
the end of
the smokeable material rod 7 abuts the end of the filter 2. The rod is wrapped
in a
paper wrapper 8, and is joined to the filter 2 by tipping paper 9 in a
conventional
manner.
Figure 2 shows an alternative embodiment in which corresponding features have
the
same reference numerals. This embodiment differs from that shown in Figure 1
in
that the capsule 15 is elongate in shape. In addition, rather than being
positioned
23 with a cavity within the filter 2, the capsule 15 is embedded within the
material of
the filter plug 13.
The liquid held within the capsule is capable of enhancing the degradation of
the
smoking article. Consequently, the selection of the liquid is dependent upon
the
composition of the materials comprising the remainder of the smoking article
and
vice-versa. In a preferred embodiment of the invention, the liquid is water
and
various components of the smoking article are water-dispersible or wet-
degradable
to some extent as outlined below. In this way, the degradation of the smoking
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article is enhanced relative to an identical smoking article lacking a water-
containing
capsule.
In the embodiment shown in the Figure 2, the capsule 15 is enclosed within the
filter material 13. In some embodiments, the filter may be a composite filter
comprising multiple filter segments. For example, the filter shown in Figure 1
comprises two sections of filter material 3 separated by a cavity 6, which
contains
the capsule. In further embodiments, the capsule may be located in a cavity
formed
between the filter material and the rod of smokeable material, or the filter
may
comprise more than two filter sections, and may even include multiple
cavities.
In the embodiments shown in the figures, the smoking article comprises a
single
capsule. In alternative embodiments, however, more than one capsule may be
used,
and in such embodiments, the capsules will generally be held within a cavity
section
formed in a multi-section filter.
The capsule may be inserted into the filter using any suitable method, and
various
methods of capsule insertion will be known to the skilled person. Suitable
apparatus
may, for example, include a means for supplying a continuous stream of filter
material from a source of such material (e.g., a bale, bobbin, or the like).
The
apparatus may further include a capsule insertion unit for inserting or
depositing the
individual capsules at predetermined intervals within the filter material. The
filter
material having capsules deposited therein may then be received into a rod-
making
means for providing a continuous rod which may subsequently be subdivided into
the desired length at predetermined intervals to form the individual filters
of the
invention.
Generally, prior art disclosures of capsules for use in smoking article
filters are
concerned with providing encapsulation methods aimed at releasing the
encapsulated material before smoking occurs. The capsules are designed to
resist
breakage only during transport and storage, when the filter is not generally
subject
to significant external pressure. The capsule is subsequently intended to be
ruptured
immediately prior to use of the smoking article, and since this is the first
exposure
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of the smoking article to significant manipulation and external pressure, the
capsule
is not necessarily required to be particularly robust.
In contrast, capsules for use in the invention are intended to be broken after
the
3 smoking article has been smoked, and thus are preferably capable of
tolerating a
significant degree of manipulation as the smoking article is smoked.
Consequently,
the capsule of the present invention should be more robust than those
generally
described in the prior art. It is important that the capsule is not
accidentally
ruptured before the smoking article is ready to be discarded. Such premature
rupture could lead to the filtration characteristics of the smoking article
being
changed and deliveries being thereby altered compared to what is expected.
On the other hand, it is important that the capsule is not overly robust as it
should
be easily breakable after smoking ceases, during the manual extinguishing
process or
13 'stubbing out'. The capsule for use in the present invention may, for
example, have a
crush strength of between 1.5 and 2.5kp, preferably between 1.7 and 2kp.
The capsule may be designed and inserted into the filter in such a way that
the
capacity to rupture is dependent upon the nature of the pressure exerted.
Pressure
exerted by the user during smoking will predominantly be exerted by the
fingers and
mouth to the circumferential surface of the smoking article ("transverse"
pressure).
In some embodiments of the invention, the capsule is to be relatively
resistant to
transverse pressure to prevent premature rupture. On the other hand, the
stubbing
out process is likely to involve the application of "longitudinal" pressure
along the
23 length of the smoking article, and consequently the capsule should
demonstrate a
relatively reduced resistance to breakage in response to longitudinal
pressure.
This directional capsule resilience may be achieved in a number of ways. For
example, the capsule may be elliptical or ovoid and consequently demonstrate
an
increased resistance to rupture when pressure is exerted in one direction
versus
another. Alternatively, directional resilience may be achieved using a capsule
which
has been specifically strengthened in certain areas. Such a capsule may be
produced,
for example, having an increased shell thickness in selected areas. Naturally,
a
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similar effect may be achieved by weakening the capsule wall in certain areas,
to
facilitate breakage or rupture in response to force being applied in a
particular
manner or direction.
The stubbing out process can also involve bending of the filter. Therefore, in
some
embodiments the capsule is designed to demonstrate increased susceptibility to
rupture when the filter is bent or buckled. For example, a long cylindrical
capsule
may be used which may be ruptured by being snapped. Such elongate capsules
will
be positioned longitudinally within the filter, so that they are easily bent
and
ruptured when the filter of the smoking article is stubbed out and bent.
Various means of encapsulating substances, particularly liquids, for release
in
smoking article filters are known, and are generally suitable for use in the
invention.
Clearly, one of the primary considerations is that the capsule should
generally be
resistant to the degrading action of the intended contents. The capsule should
also
comprise material which has a melting point above the temperature of the smoke
within the filter.
The capsule may exhibit brittleness under stress and/or may comprise a line of
weakness, such as a scored line, a brittle point, or a weak section.
Alternatively, a
piercing means may be incorporated within the filter.
In preferred embodiments, the capsule is constructed from a frangible
material. In
one embodiment the capsule is composed of a low solubility, high molecular
weight
polyvinyl alcohol. A number of suitable alternative materials are known, and
by way
of example, capsules typically utilized in the pharmaceutical industry may be
used.
Such capsules may be gelatin based, for example, or may be formed from a
polymeric material, such as modified cellulose. One type of modified cellulose
which may be used is hydroxypropylmethyl cellulose. Many biodegradable
materials
are known which may be suitable for use in the production of capsules and
these
include high molecular weight polyethylene glycols, polylactic acid, plastarch
material, polycaprolactone, polyglycolide, a polyhydroxyalkanoate such as poly-
3-
hydroxybutytate, and zein-derived bioplastics.
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Alternatively, the capsule may comprise a length of thin-walled glass tubing,
the
ends of which may be sealed by heating or with a material capable of
withstanding
manual handling prior to and during smoking, yet which can be fractured after
smoking. Other suitable materials include thin-walled aluminium tubing or
hollow
foodstuff material, such as, for example, pasta, or extruded hollow tubing of
reconstituted tobacco material. The inner walls of the capsule material may
advantageously be coated with a varnish or waterproof material, such as
silicone, to
preserve the rigidity of the capsule material by preventing absorption of, or
degradation by, the liquid contents over a prolonged period.
The capsule may alternatively be comprised of a wax, resin, natural or
synthetic
gum, latex or plastic material which retains its shape and strength at room
temperature and at smoking temperature but which fractures to release the
liquid
contents upon pressure applied to extinguish the smoking article. Examples of
suitable waxes include beeswax, candelilla, carnauba, Shellac wax, caranday,
sugarcane wax, myrtle wax and petroleum wax.
Suitable resins include epoxy resins, terpene resins, petroleum resins, ester
gum,
phenolic resins and rosin based resins. Preferred gums include gum arabic,
locust
bean, guar, alginates, carrageenan and pectin.
Preferably the substances comprising the capsule have no effect on the taste
of the
mainstream smoke as smoking occurs.
The capsule may be formed in a variety of physical formations including
singular
part or multipart capsules, large capsules, small capsules, microcapsules,
etc. A
number of different capsule configurations are suitable for use in the
invention; for
example, the capsule may be generally spherical (as shown in Figure 1), ovoid,
ellipsoidal (as shown in Figure 2), cylindrical, or may approximate to a
polygonal
prism in shape.
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The capsule may be coloured. For example, the capsule may comprise a colouring
agent. The colouring agent may be used to render more easily the location of
the
capsule within the filter during the manufacturing process. Alternatively or
additionally, the colouring agent may provide an interesting and attractive
appearance to the smoking article, particularly if the capsule or capsules are
intended to be only partially enclosed within the filter material, or if the
tipping
paper is intended to have a transparent window portion.
Alternatively or in addition, the liquid held in the capsule may be coloured.
This
would give the user an additional, visual indication that the liquid has been
successfully released and that degradation of the spent smoking article will
be
enhanced. A coloured liquid also has the added benefit that it could act as an
indicator when the capsule is accidentally ruptured before smoking. The colour
would be a warning to the smoker that the smoking article has been damaged and
should not be smoked.
The size of the capsule is clearly dependent on the volume of liquid required,
but
consideration should be given to the fact that the presence of the capsule in
the
filter should not have an adverse effect on the filtration or draw
characteristics of
the filter.
In one preferred embodiment, the capsule is 5mm in diameter. Generally, the
diameter of the capsule may be up to 80% of the diameter of the smoking
article.
Preferably the capsule diameter is up to 70%, up to 60%, or up to 50% of the
diameter of the smoking article. For example, the diameter of the capsule may
be
between 2 and 7mm, and preferably the diameter is between 4 and 6mm.
The capsule should be large enough to accommodate sufficient contents to
enhance
the degradation of the smoking article. The volume required will vary
according to
the nature of the liquid held within the capsule, the composition of the
remainder of
the smoking article and the associated capacity of the liquid to enhance the
degradation of the smoking article. The volume of the capsule may be up to
60%,
up to 50%, up to 40%, or up to 30% of the total volume of the filter. The
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requirement for a large volume of liquid should be balanced, however, with the
need
to retain sufficient filter material within the filter to provide the required
degree of
filtration.
While it is preferable for the volume of the capsule to be as large as
possible, as the
size of the capsule is increased, the risk of premature breakage of the
capsule is also
increased. Furthermore, the larger the capsule, the greater is the obstruction
to the
smoke flow path. Consequently, to accommodate the required amount of liquid,
it
may be preferable for the filter to comprise two, three, four or more
capsules.
Multiple capsules may be positioned, for example, at regularly spaced
intervals along
the length of the filter. Alternatively, multiple capsules may be situated as
a cluster
within the filter, for example within a cavity formed between two sections of
filter
material.
Alternatively, long cylindrical or ellipsoidal capsules (or tubes) may be
used, having
a length equal to a significant proportion of the length of the filter, or
even equal to
the entire length of the filter. Such capsules may be up to 5mm in diameter.
Multiple capsules may be used comprising different liquids.
In some embodiments, the capsule or capsules may be further encapsulated in a
second capsule, or a sheath, or the like. This may allow greater protection
from
accidental or premature breakage, or incidental leakage. In this way, single
wall or
multi-wall capsules may be used to tailor capsule stability, strength, rupture
resistance, processing ease in filter making, etc.
The capsule may be manufactured using any suitable method, the method of
manufacture of the capsule clearly being dependent on the precise composition
and
make-up required. Various methods of capsule manufacture will be known to the
skilled person, including techniques such as co-extrusion, spin coating,
coacervation, interfacial polymerization, solvent evaporation, and annular jet
forming.
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In some embodiments in which the capsule is a seamless capsule, the capsule
may
be produced using a co-extrusion process. The co-extrusion process is a
synchronous extrusion of the two liquids that will subsequently form the shell
and
the capsule contents (or "core"). The first (co-extrusion) step involves
forming a
droplet having the liquid core material inside the liquid shell material.
After the co-
extrusion step, the "capsule" is solidified by cooling or by immersion in a
curing
agent, for example. The capsules may then be subjected to various treatments,
such
as washing, removal of surplus liquid, colouring, application of additional
coatings,
etc.
Alternatively, an annular jet forming technique may be used. This method
utilises
two concentric jets to eject an inner jet of liquid core material and an outer
jet of
liquid shell material. The fluid stream breaks into droplets and the liquid
shell
material solidifies by phase transition induced by the presence of cross-
linking ions,
pH differences, temperature changes, etc.
In some embodiments in which the capsule comprises a wax capsule, the capsule
may be formed, for example, by a method comprising freezing a solution of the
liquid core material until small crystals are formed. According to this
method, the
crystals are then dropped into molten wax and removed by spatula after a wax
coat
has formed around the cold crystals. The frozen cote material gradually
becomes
liquid as the coated capsule reaches room temperature.
In alternative embodiments, the capsule may be manufactured in situ. For
example,
in embodiments in which the capsule comprises a long cylindrical capsule
extending
the entire length of the filter, the capsule may be constructed by crimping a
continuous tube into filter-length fragments as part of the filter
manufacturing
process.
The liquid held within the capsule may be any liquid capable of enhancing the
degradation of one or mote of the materials comprising the remainder of the
smoking article. Clearly the nature of the liquid is dependent upon the
composition
of the materials of the smoking article and vice-versa.
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The disintegration and/or degradation of the smoking article may be enhanced
in
one or more of the following ways. Firstly, the dissociation of the smoking
article
may be enhanced, resulting in the individual components having greatly
increased
exposure to the environment and thus being susceptible to accelerated
degradation.
Secondly, the degradation of one or more of the individual components may be
directly enhanced, for example one or more of the components may be soluble or
otherwise reactive with the liquid held within the capsule.
Smoking articles generally comprise a number of different papers (tipping
paper,
plugwrap, and tobacco wrapping paper) which bind the various components of the
smoking article and hold them together. In some embodiments, the dispersion of
the adhesive which binds these papers, and/or the papers themselves is
enhanced by
the action of the liquid in the capsule. In one preferred embodiment the
liquid is
water, the adhesive is a water-soluble or a water-dispersible adhesive, and
the
plugwrap and tipping papers comprise moisture disintegrative papers. Thus,
when
the capsule is ruptured, the water acts on the adhesive, the plugwrap, and the
tipping paper, enhancing the dissociation of the smoking article and
accelerating the
environmental degradation of the various components of the smoking article.
There are a number of means by which the liquid may enhance the degradation of
the smoking article. When the capsule is ruptured, the liquid is released and
is able
to migrate throughout the smoking article. In some embodiments, the liquid
held
within the capsule is an aqueous solution, and one or more of the remaining
components of the smoking article are in some way water-degradable, for
example,
composed of water-soluble or water-dispersible material. In one embodiment,
the
liquid within the capsule is water, and the filter material is a water-soluble
or water-
dispersible material, such as polyvinyl alcohol.
In alternative embodiments, other liquids may be used in the capsule, and
clearly the
selection of liquid to be used is dependent on the composition of the other
components of the smoking article.
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Generally the preferred liquids for use in the capsule are aqueous solutions,
and the
most preferred liquid is water. Weak acidic or basic solutions may be used. In
general, any liquid may be used that is not potentially toxic or harmful to
the user.
In case of the accidental premature breakage of the capsule, it is also
important that
none of the other components of the smoking article degrade to yield products
which are potentially toxic or harmful to the user.
The liquid may be coloured. This may serve as a visible indication that the
capsule
has been ruptured, which may be important for two reasons. Firstly, this will
inform
the user if the capsule is prematurely broken, thus alerting the user that the
smoking
article should not be smoked. Secondly, when the user is attempting to break
the
capsule, this will serve as confirmation to the user that the capsule has
indeed been
satisfactorily ruptured. The interesting possibility of observing a coloured
liquid
may also serve as an incentive to encourage users to break the capsule upon
disposal
of the smoking article.
In some embodiments, the degradation of the smoking article is enhanced by
means
of a chemical reaction between the liquid and one or more of the remaining
components of the smoking article, such as the filter material. The chemical
contained within the capsule may be selected to react specifically with the
particular
component of the smoking article. Alternatively, the chemical may show a less
selective capacity to chemically react with and degrade the smoking article,
for
example the chemical may be a weakly acidic solution.
The filter may comprise two or more capsules containing different liquids. The
different liquids may react together or otherwise combine to form a liquid
capable
of enhancing the degradation of the smoking article. Alternatively, different
components of the smoking article may be subject to degradation by different
liquids.
In some embodiments, the capsule contains a solution which acts as an
attractant to
microorganisms, insects, or other organisms. Thus, the rate of degradation of
the
smoking article is effectively enhanced by the action of the living organisms.
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According to these embodiments, the capsule may contain an environmentally
acceptable aqueous solution of, for example, glucose (or other sugar
solution), salt
(as a saline solution), or starch (as a thin corn starch syrup). The skilled
person will
be aware that in all of these embodiments the selection of the materials
comprising
the reminder of the smoking article is important to promote the action of the
microorganisms.
The capsule is intended to be ruptured upon disposal of the smoking article,
and
frequently, spent smoking articles are associated with undesired odours.
Therefore,
in addition to the degrading action, the liquid may additionally possess
deodorising
qualities. Alternatively, individual degrading and deodorising liquids may be
incorporated into the filter in separate capsules, to be ruptured
simultaneously.
The deodorising agent may be a neutralising agent or a masking agent, or be a
combination of neutralising and masking agents.
Preferred deodorisers include 2-trans-3,7-dimethy1-2,6-octadien-8-ol (often
known
as geraniol), 1-carvone, 1-carveol, terpinyl acetate, geranyl propionate,
citronelly1
butyrate, citral, cis-3-hexenol, triacetin, benzyl benzoate, acetone, safrole,
terpinyl
propionate, methyl salicylate, hexyl cinnamic aldehyde, isopropyl alcohol,
triethylglycol diacetate (TEGDA), OdorGoneTm, methyl cinnamaldehyde, linalyl
propionate, acetic acid, citronellal, citronellyl formate, geranyl formate and
linalool.
Mixtures of these compounds are also suitable. Many other masking agents, such
as
perfumes, e.g. essential oils used in pot pourri, are also suitable compounds
for use
in the present invention.
The filter material used in the filters of the vast majority of currently
available
smoking articles is composed of cellulose acetate fibres and does not readily
disintegrate or biodegrade.
The filter material of one embodiment of the invention is composed of
polyvinyl
alcohol. Polyvinyl alcohol is commercially available as a thermoplastic, water
soluble, solid polymer that is relatively inexpensive and non-toxic. Polyvinyl
alcohol
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is unique in being the only biodegradable, carbon-carbon backbone polymer
capable
of complete biodegradation under environmental conditions. Thus, in the
embodiment shown, when the spent smoking article is discarded, the user
ruptures
the capsule, for example by squeezing the filter, or by stepping on the spent
smoking article. This releases the water contained within the capsule, which
migrates throughout the filter, and promotes the degradation of the polyvinyl
alcohol filter material.
In alternative embodiments, other water-degradable substances may be used,
such
as starch, ethylene vinyl alcohol copolymers, polylactic acid, creped paper
manufactured from a wood pulp sheet, or a regenerated cellulose fibre bundle.
As described above, the liquid may not act to dissolve the filter material,
but may
enhance the degradation of the smoking article via some other mechanism. For
example, in some embodiments, the filter material may be cellulose acetate
which
has been manufactured using a water-soluble plasticizer to bind the cellulose
acetate
fibres. According to these embodiments, the liquid may be water, and other
components, such as the plugwrap, tipping paper, and/or adhesive, may also
preferably be water-soluble or water-dispersible. Consequently, rupture of the
capsule results in dissociation of the components of the filter, including
dispersion
or dissolution of the plasticizer. As a result, the cellulose acetate fibres
are no longer
bound to one another and the filter material disintegrates and the individual
cellulose acetate fibres are able to disperse. As an alternative to the use of
a water-
soluble plasticizer, non-woven or loose processed cellulose acetate fibres may
be
used.
In embodiments in which the liquid promotes the dissociation of the components
of the smoking article, the filter may further comprise a material or powder
which is
capable of expansion upon the action of the liquid. In this way, rupture of
the
capsule results in expansion of this substance and consequent rupture of the
filter.
Suitable materials capable of expansion will be known to the skilled person.
For
example, materials which will swell upon contact with water include
carboxymethyl
cellulose, water-dispersible starch, chemically modified starch, and super
absorbent
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polymers such as a cross-linked copolymer of acrylic acid and sodium acrylate
or a
cross-linked copolymer of acrylamide and potassium acrylate. These materials
may
be incorporated into the filter, for example in powder form, and will swell
when
exposed to water, for example water from the capsule of the invention. The
swelling action physically separates the components of the filter, enhancing
disintegration of the structure and dispersion of the components.
In other embodiments, the liquid may be an aqueous solution comprising
biological
agents capable of degrading the cellulose, such as cellulase enzymes.
In some embodiments, the filter material may comprise paper. The liquid may be
water, which will not dissolve paper but will nevertheless enhance its
disintegration
and degradation.
Filter materials may be used which are not biodegradable per se but may be
disintegrated or converted into a biodegradable form by the action of a
particular
chemical held within the capsule.
Many smoking articles are configured to entrain a flavourant within the smoke
that
is drawn along the smoking article by the user. This is frequently achieved by
the
incorporation of flavourant-containing capsules within the smoking article
filter. In
such smoking articles, encapsulation prevents the volatile flavourant from
evaporating prematurely, with the capsule being ruptured to release the
flavourant
prior to use of the smoking article. This method of flavouring smoking
articles is
not obviously compatible with the degradable smoking articles described
herein,
however. This is due to the abundance of capsules that would be required in
the
filter, and the fact that the flavourant capsules should be ruptured prior to
smoking,
whereas the capsules of degrading liquid should be broken upon disposal of the
spent smoking article.
Consequently, in some embodiments of the present invention, the filter may
comprise a thread passing along a longitudinal axis of the filter from the
tobacco
rod end to the mouth end. According to these embodiments, the threads are
loaded
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with aromatic or flavourant material. Thus, as smoke is drawn along the
smoking
article, flavourant held within the thread becomes entrained in the smoke. The
use
of a flavourant-enriched thread also provides a simple means of incorporating
flavourant into the smoking article filter, requiring minimal modification of
the
manufacturing process.
As used herein, the term "flavour", "flavouring", and "flavourant" refer to
materials
which may be used to create a desired taste or aroma. Preferred flavourants
include
extracts (e.g., licorice, hydrangea, Japanese white bark magnolia leaf,
chamomile,
fenugreek, clove, menthol, Japanese mint, aniseed, cinnamon, herb,
wintergreen,
cherry, berry, peach, apple, Drambuie, bourbon, scotch, whiskey, spearmint,
peppermint, lavender, cardamon, celery, cascarilla, nutmeg, sandalwood,
bergamot,
geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, cassia,
caraway,
cognac, jasmine, ylang-ylang, sage, fennel, piment, ginger, anise, coriander,
coffee,
or a mint oil from any species of the genus Mentha), flavour masking agents,
bitterness receptor site blockers, receptor site enhancers, sweeteners (e.g.,
sucralose,
acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose,
glucose,
fructose, sorbitol, or mannitol), and other additives such as chlorophyll,
minerals,
botanicals, or breath freshening agents. They may be imitation, synthetic or
natural
ingredients or blends thereof.
The preferred material for the manufacture of the thread is cotton, although
other
materials such as cellulose acetate and rayon, or natural materials such as
plant
fibres, may also be used. According to these embodiments, the liquid held
within
the capsule may be capable of degrading the flavourant-enriched thread.
In some preferred embodiments of the present invention, moisture
disintegrative
papers are used as the plugwrap, tobacco wrapping paper and tipping paper.
Thus
when the capsule is ruptured, water is released, and the degradation of the
paper
wrappers is enhanced, promoting the dissociation of the smoking article.
In alternative embodiments, one or more of the papers used in the smoking
article
may not be disintegrated by water, but may be otherwise biodegradable. In
other
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embodiments, one or more of the papers are not biodegradable per se but may be
disintegrated by the action of a particular chemical held within the capsule,
such as a
weakly acidic solution, for example.
3 In order to produce an unusual visual effect, in some embodiments, the
filter
comprises a transparent window which allows visualisation of the filter
material
and/or capsule within the filter. In some such embodiments, the capsule is
held in a
cavity formed between two pieces of filter material and the transparent window
is
aligned with the cavity section of the filter material. In this way the user
is provided
with the unusual effect of being able to visualise the capsule within the
filter, and
this may serve as a reminder to break the capsule once the smoking article has
been
smoked. To produce the effect of a transparent window, the tipping paper may
comprise a single piece of transparent material, which can be, but is not
limited to,
one of polypropylene, polyvinyl chloride (PVC), cellulose acetate film,
polyethylene
13 terephthalate (PET), polyethylene oxide (PEOX), polyethylene,
cellophane,
NatureflexTm, polylactic acid, plastarch material, polycaprolactone,
polyglycolide, a
polyhydroxyalkanoate such as poly-3-hydroxybutyrate, and zein-derived
bioplastics.
The tipping paper has an opaque coating on certain portions to leave a
transparent
uncoated section which defines the window. Since the material will be in
contact
with moisture from the user's mouth and fingers, the transparent material used
is
either insoluble, or is treated with a water-resistant external coating.
According to
these embodiments comprising a transparent material, the liquid held within
the
capsule may be capable of degrading the transparent material.
23 Adhesive is generally used to bond the seams of the plugwrap, tipping
paper, and
cigarette paper of a smoking article. In preferred embodiments of the
invention,
water-soluble or water-dispersible adhesives are used. Water released from the
capsule when it is ruptured causes loss of the bonding between the various
components of the smoking article, resulting in the individual components
having
greatly increased exposure to the environment, and thus being susceptible to
accelerated disintegration and biodegradation.
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The preferred water soluble adhesives for the seam adhesives are liquid starch
adhesives. Hot melt adhesives, or EVA and PVA adhesives may also be used.
In some embodiments, one or more of the adhesives used are not water soluble.
In
this case, a solvent is held within the capsule which acts to soften or
solubilise the
adhesive, promoting disintegration of the smoking article.
Although the vehicle containing the liquid capable of enhancing the
disintegration
and/or dispersion of the smoking article has been generally described above as
being a capsule, other fluid-containing vehicles can be used. For instance,
pockets
or pouches formed directly within a filter material or from a separate
material such
as polyethylene could be used, to be ruptured once the smoking article has
been
smoked. Also, a sponge-like porous material such as a foamed plastic polymer
could be used to contain the fluid, which could be released via a squeezing or
twisting action once the smoking article has been smoked. Other suitable fluid-
containing arrangements would be evident to those skilled in the art.
Above is described what is believed to be the preferred embodiment of the
invention. However, those skilled in the art will recognise that changes and
modifications may be made without departing from the scope of the invention a
defined in the claims.
