Note: Descriptions are shown in the official language in which they were submitted.
WO 2013/12-1475 eA 02863465 2014-07-31
PCT/EP2013/053654
Tobacco Smoke Filter
The present invention relates to filters and filter elements for smoking
articles such
as cigarettes.
There is a widespread desire to reduce the problems associated with the
environmental impact of cigarette butt litter. The vast majority of current
cigarette filters are
constructed using conventional cellulose acetate filamentary tow, for which
the rate of
biodegradation is very slow. This causes issues when butts are discarded on
the ground
such that the filters can remain clearly identifiable for prolonged periods of
time. In addition,
current cellulose acetate filters do not disperse when discarded into
waterways and their
characteristic size and shape is retained even after lengthy immersion in
water. This
causes problems in waste water treatment plants where used butts have to be
removed
from the water stream during the treatment process. Of course, many butts that
are
originally discarded on land will ultimately end up in water treatment plants
after they have
been swept away down drains following rainfall. Thus, there is a need for a
cigarette filter
that is made from readily biodegradable materials and which disperses rapidly
when
immersed in water. In addition, the filter material must satisfy numerous
other criteria, in
particular being in a form suitable for high speed conversion into cigarette
filters; provide
suitable characteristics (e.g. filtration efficiency, hardness, lack of
variability, etc) to the
finished filter; be economically viable; and enable acceptable subjective
characteristics
(notably taste and appearance) in the final cigarette.
This is not a new problem and researchers have been endeavouring to find a
suitable biodegradable cigarette filter material for decades. Numerous patent
applications
have been filed over this time for materials that are claimed to address these
requirements
but as yet none have gained any significant market acceptance. There remains,
therefore,
a need for a tobacco smoke filtering material which is readily biodegradable,
disintegrating
very rapidly when immersed in water.
According to the present invention in a first aspect there is provided a
tobacco smoke filter
or filter element including a nonwoven fabric, wherein the nonwoven fabric
comprises: a
sheet of staple fibres; and a water soluble binder; wherein the water soluble
binder is
uniformly coated on at least one face of the sheet of staple fibres.
According to the present invention in another aspect there is provided a
tobacco
smoke filter or filter element including a nonwoven fabric, wherein the
nonwoven fabric
comprises: staple fibres (e.g. a sheet of staple fibres); and a water soluble
binder; wherein
the water soluble binder is applied to the staple fibres in aqueous form.
Nonwoven fabrics may be defined as sheet or web structures bonded together by
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entangling fibres or filaments (and by perforating films) mechanically,
thermally or
chemically. They may be made directly from separate fibres (or from molten
plastic or
plastic film). Herein, the term "nonwoven fabric" expressly does not include
paper or base
paper.
Preferably the non woven fabric is a wet laid non woven fabric. The nonwoven
fabric may have basis weight of 25 to 42 gsm, for example 27 to 40 gsm.
The staple fibres are preferably of a biodegradable material. The staple
fibres may
be regenerated cellulosic fibres, e.g. Viscose or Tencel, both of which are
available from
Lenzing AG. Other biodegradable fibres, such as Polyvinyl Alcohol (PVOH),
Polylactic Acid
(PLA), Polyglycolic acid (PGA) or cotton may also be used. It is possible to
use less
degradable or non biodegradable fibres, e.g. cellulose acetate fibres,
cellulosic ester fibres,
but these are not preferred. Preferably, the staple fibres are not cellulose
acetate fibres or
cellulose ester fibres.
Preferably the filter/filter element and/or nonwoven fabric and/or staple
fibres have
the 'Ready Biodegradability' level of biodegradability as measured according
to OECD
301B 'Ready Biodegradability' method (modified Sturm test), which is well
known in the art.
The staple fibres may be staple fibres of cut length 4 mm to 10 mm, for
example 4
to 6 mm. The staple fibres may be of diameter 1.7 dtex to 3.3 dtex. The staple
fibres may
be of any cross-section (e.g. round, trilobal, etc). It will be appreciated
that staple fibres of
any cut length and diameter suitable for use in a wet laid nonwoven fabric may
be used
and that a blend of different fibres, fibre lengths or fibre diameters may be
used in the
fabric.
The amount of water soluble binder may be 0.1 % to 5%, for example 0.5 to 3 %,
for example 1%, expressed as percentage of the solids level content in the
finished
nonwoven fabric. The water soluble binder may be carboxymethyl cellulose
(CMC),
polyvinyl alcohol (PVOH), hydroxycellulose, polyethylene oxide, natural
starch, a modified
starch, a cationic starch, guar gum, or a derivative of the above. The binder
can be applied
by any known method suitable for the application of liquid binders such as
curtain coating,
size press, mangle padding, spray, etc. Preferably the nonwoven fabric does
not include
an alkaline compound.
The filters and element of the invention include a nonwoven fabric which
comprises
(e.g. short cut biodegradable) staple fibres (e.g. regenerated cellulosic
fibres) and a water-
soluble binder. Preferably, the water soluble binder is applied (to the
fibres) in an aqueous
form. Preferably, the water soluble binder is applied (to the fibres) in an
aqueous form and
subsequently dried.
The specific nonwoven fabric material is preferably manufactured by a wet laid
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process. Nonwovens can be prepared by a variety of different well known
manufacturing
routes (e.g. dry laid or 'carded', spunbound, wet laid, air laid, etc). The
present applicants
have found that wet laid fabrics are best suited to meeting the demanding tip-
to-tip
pressure drop reproducibility criteria required for cigarette filters, which
is a vital
prerequisite for a viable tobacco smoke filtering material (regardless of its
dispersability
characteristics). The pressure drop is related to the weight of fabric used
per tip. The basis
weight of papers and nonwovens is measured using a standard method that
quantifies the
weight of an area at least 20 x 25 cm. The quantity used in a typical
cigarette filters uses
only around 10% of this quantity, so data based on the weight variability of
such larger test
specimens can be misleading as to their suitability to meet the
reproducibility criteria for
cigarette filters. By measuring the weight variability of fabric strips of 2cm
x 30cm, the
applicants determined that wet laid nonwovens were best suited to meeting the
required
weight variability requirements of not greater than around 1%.
A wet laid fabric made from 100% staple fibre is extremely weak and does not
have
sufficient mechanical integrity to withstand processing on filter-making
machinery. Thus, a
binder is needed to provide sufficient strength to the fabric. Prior art wet
laid fabrics often
incorporate a thermoplastic binder fibre as part of the fibre furnish; these
binder fibres are
then activated during the drying stage of fabric manufacture. However, the
present
applicants have found that fabrics that incorporate binder fibres are
unsuitable for this
application because they do not readily disperse in cold water (see
Comparative Example 3
below). The applicants have found that the use of a (e.g. liquid) water
soluble binder with
the staple fibres results may enable rapid dispersion in cold water.
The non woven fabric may be a fabric having a dispersibility wherein 95% or
more,
for example 96% or more, of the nonwoven fabric passes through 6.3mm aperture
screens
after being subjected to EDANA Standard FG511.1 Tier 1 Dispersability Shake
Flask Test
(using screens of 1.6, 3.15, 6.3 and 12.5 mm aperture). This test is well
known in the art,
and this dispersibility indicates ready and effective dispersion in cold water
(high
dispersibility).
The end appearance and hardness characteristics of filters according to the
invention are also similar to those of cellulose acetate, again enhancing
their commercial
acceptability.
Advantageously, the nonwoven fabrics used in filters according to this
invention
may be processed (e.g. embossed) using standard equipment which is used for
making
paper-based cigarette filters. Paper filters give greater tar retention than
cellulose acetate
filters of the same pressure drop. This means that it is not possible for the
cigarette
producer to simply replace a cellulose acetate filter with a paper filter,
because either the
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length of the filter would need to change (to maintain the same pressure drop
or tar
delivery) or the cigarette tar delivery would decrease and pressure drop
increase (for a
constant filter length). The present applicants have found that the tar
retention of filters and
filter elements according to the invention are much closer to those of
cellulose acetate
rather than paper. The present applicants also found that the more open and
inherently
porous the fabric structure, the lower the tar retention of the filter
incorporating that
material. Thus, the porosity of the nonwoven fabric may be engineered by
controlling the
constituent fibre properties such as polymer type, fibre cross-section, fibre
crimp and fibre
dimensions, to provide filters and filter elements of desirable tar retention
and pressure
drop. This means that the filters/elements of the invention find further
advantage because
they may be used as a simple replacement for cellulose acetate filters.
The nonwoven fabric may further comprise wood pulp. Herein, the term wood pulp
includes a pulp comprising a naturally occurring cellulose fibre (e.g.
obtained from a soft
wood or hard wood by conventional method such as Sulfite method or Kraft
method) which
may have been beaten (as is well known in the art) e.g. with the use of a
conventional
beating machine or refining machine. Wood pulp may enhance the tensile
strength of the
nonwoven fabric. If wood pulp is included it is preferred that it is present
in an amount of
0.1 to 20%, for example 5 to 10%, by weight of the non-woven fabric. In a
preferred
example, wood pulp is included in an amount of up to 9.5%, for example 1 to
9%, for
example 5 to 9%, by weight of the non-woven fabric. The applicants have
surprisingly
found that the non-woven fabric including this rather small amount of wood
pulp (in addition
to the water soluble binder) is sufficiently strong to be formed into
filters/filter elements. In
a different, preferred example, wood pulp is included in an amount of up to
20%, for
example 1 to 20%, by weight of the non-woven fabric; and the water soluble
binder is
present in an amount of 0.1% to 5%, expressed as percentage of the solids
level content in
the finished non-woven fabric.
Thus, according to the present invention in an aspect there is provided a
tobacco
smoke filter or filter element including a nonwoven fabric, wherein the
nonwoven fabric
comprises: a sheet of staple fibres; woodpulp; and a water soluble binder;
wherein the
water soluble binder is uniformly coated on at least one face of the sheet of
staple fibres;
and wherein up to 9.5% by weight of the non-woven fabric is wood pulp.
According to the present invention in another aspect there is provided a
tobacco
smoke filter or filter element including a nonwoven fabric, wherein the
nonwoven fabric
comprises: a sheet of staple fibres; woodpulp; and a water soluble binder;
wherein the
water soluble binder is uniformly coated on at least one face of the sheet of
staple fibres;
wherein the non-woven fabric comprises wood pulp in an amount of up to 20% by
weight of
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the non-woven fabric, and the amount of binder is 0.1 to 5% expressed as
percentage of
the solids level content in the finished non-woven fabric. Preferably, the
staple fibres are
not cellulose acetate fibres or cellulose ester fibres.
The tobacco smoke filter or filter element may further comprise a flavour
enhancing
additive. The flavour enhancing additive may be an additive as disclosed in WO
2010/136751for use in paper filters. The flavour enhancing additive may be an
alicyclic
lactone, an aromatic lactone, an aromatic ketone, or secondary alcohol or
ester thereof, a
phthalide, x-Valerolactone, x-Hexalactone, 8-Hexalactone, x-Heptalactone, x-
Octalactone,
6-Octalactone, 4-Hydroxy-3-pentenoic acid lactone, 5-Hydroxy-2-decenoic acid 8-
lactone,
4,4-Dibutyl-x-butyrolactone, Mintlactone, Dehydromenthofurolactone, 3-
Butylidenephthalide, 3-n-Butylphthalide, Whiskey lactone or sedanenolide.
The tobacco smoke filter or filter element may comprise a longitudinally
extending
core of tobacco smoke filtering material. The tobacco smoke filtering material
may include,
or be, the nonwoven fabric. The longitudinally extending core of tobacco smoke
filtering
material may be substantially cylindrical.
A tobacco smoke filter or filter element according to the invention may be of
circumference 14 to 28 mm, for example 16 to 26 mm, for example 16 to 17 mm or
24 to 25
mm. A tobacco smoke filter of the invention may be of length 10 to 40 mm, e.g.
15 to 35
mm, e.g. 20 to 30 mm. A tobacco smoke filter element of the invention may be
of length 5
to 30mm, e.g. 6 to 20mm, e.g. 8 to 15 mm, e.g. 10 to 12 mm.
The tobacco smoke filter or filter element of the invention may further
comprise a
wrapper of e.g. plugwrap. The wrapper is preferably engaged around the tobacco
smoke
filter or filter element (e.g. around the longitudinally extending core of
tobacco smoke
filtering material). The wrapper (e.g. plugwrap) is preferably held in place
with a water
soluble adhesive (e.g. by means of a lapped and stuck seam as is known in the
art). The
water soluble adhesive advantageously facilitates the opening of the filter on
contact with
water to expose the filter material (nonwoven fabric) contained therein,
thereby facilitating
break down of the filter (nonwoven fabric) after use.
Filters or filter elements of the invention may be used as single filter tips,
as filter
rods, as one or more segments within a multi-segment filter etc. Thus, a
filter element
according to the invention may be used as a segment of a dual, triple, or
other multi
component (multiple segment), filter. Dual and other multiple component
filters are known
in the art.
Filters according to the invention may be used in machine made cigarettes
(e.g. those mass produced and packaged). Filters according to the invention
may also be
used as a filter tip for use with an individually rolled cigarette (e.g. a
hand rolled cigarette)
or a Roll Your Own or Make-Your-Own product.
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According to the present invention in a further aspect, there is provided a
filter
cigarette which includes a tobacco smoke filter or filter element according to
the invention.
In a filter cigarette according to the invention, a filter of the invention
(or a filter which
includes a filter element of the invention) is joined to a wrapped tobacco rod
with one end
toward the tobacco. The filter may, for example, be joined to the wrapped
tobacco rod by
ring tipping (which engages around just the adjacent ends of a [wrapped]
filter and rod to
leave much of the filter wrapper exposed) or by a full tipping overwrap (which
engages
around the full filter length and adjacent end of the tobacco rod). Preferably
the plug
wrap/overwrap and/or tipping paper includes a water soluble lap adhesive. The
water
soluble adhesive advantageously facilitates the opening of the filter on
contact with water to
expose the filter material (nonwoven fabric) contained therein, thereby
facilitating break
down of the filter (nonwoven fabric) after use.
Any filter or filter cigarette according to the invention may be unventilated,
or may
be ventilated by methods well known in the art, e.g. by use of a pre-
perforated or air-
permeable plugwrap, and/or laser perforation of plugwrap and tipping overwrap.
The filters or filter elements according to the invention may be made (by
methods
known in the art) as continuous rods. The continuous rod as it issues
continuously from
the production machine outlet is cut into finite lengths for subsequent use.
This cutting may
be into individual filters or filter elements as defined and described above,
each of which is
then attached to an individual wrapped tobacco rod to form a filter cigarette.
More usually,
however the continuously issuing rod of filters is first cut into double or
higher multiple
(usually quadruple or sextuple) lengths for subsequent use; when the initial
cut is into
quadruple or higher lengths, then the latter are subsequently cut into double
lengths for the
filter cigarette assembly - in which the double length filter rod is assembled
and joined (by
ring tipping or full tipping overwrap) between a pair of wrapped tobacco rods
with the
combination then being severed centrally to give two individual filter
cigarettes. Similar
techniques are used with e.g. double length filter elements which are combined
to make
dual or multiple filters, as is known in the art. The invention includes
double and higher
multiple length filter rods (and/ or filter element rods).
According to the present invention in a further aspect there is provided a
nonwoven
fabric, wherein the nonwoven fabric comprises: a sheet of staple fibres; and a
water soluble
binder; wherein the water soluble binder is uniformly coated on at least one
face of the
sheet of staple fibres. According to the present invention in another aspect
there is
provided a nonwoven fabric, wherein the nonwoven fabric comprises: staple
fibres (e.g. a
sheet of staple fibres); and a water soluble binder; wherein the water soluble
binder is
applied to the staple fibres in aqueous form. Preferably the non woven fabric
is a wet laid
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non woven fabric. The nonwoven fabric of the invention comprises (e.g. short
cut
biodegradable) staple fibres and a water-soluble binder. Preferably, the water
soluble
binder is applied (to the fibres) in an aqueous form. The staple fibres may be
staple fibres
of cut length 4 mm to 10 mm, for example 4 to 6 mm. The staple fibres may be
of diameter
1.7 dtex to 3.3 dtex. The staple fibres may be of any cross-section (e.g.
round, trilobal,
etc). It will be appreciated that staple fibres of any cut length and diameter
suitable for use
in a wet laid nonwoven fabric may be used and that a blend of different
fibres, fibre lengths
or fibre diameters may be used in the fabric.
The staple fibres are preferably of a biodegradable material. The staple
fibres may
be regenerated cellulosic fibres, e.g. Viscose or Tencel, both of which are
available from
Lenzing AG. Other biodegradable fibres, such as Polyvinyl Alcohol (PVOH),
Polylactic Acid
(PLA), Polyglycolic acid (PGA) or cotton may also be used. It is possible to
use less or non
biodegradable cellulose acetate fibres but these are not preferred.
The nonwoven fabric may further comprises wood pulp. Wood pulp may enhance
the tensile strength of the nonwoven fabric. If wood pulp is included it is
preferred that it is
present in an amount of 0.1 to 20%, for example 5 to 10%, by weight of the non-
woven
fabric.
The amount of water soluble binder may be 0.1 % to 5%, for example 0.5 to 3 %,
for example 1%, expressed as percentage of the solids level content in the
finished
nonwoven fabric. The water soluble binder may be carboxymethyl cellulose
(CMC),
polyvinyl alcohol (PVOH), hydroxycellulose, polyethylene oxide or starch. The
binder can
be applied by any known method suitable for the application of liquid binders
such as
curtain coating, size press, mangle padding, etc. Preferably the nonwoven
fabric does
not include an alkaline compound.
In a preferred example, wood pulp is included in an amount of up to 9.5%, for
example 1 to 9%, for example 5 to 9%, by weight of the non-woven fabric. The
applicants
have surprisingly found that the non-woven fabric having this rather small
amount of wood
pulp (in addition to water soluble binder) is sufficiently strong to be formed
into filters/filter
elements. In a different, preferred example, wood pulp is included in an
amount of up to
20%, for example 1 to 20%, by weight of the non-woven fabric; and the water
soluble
binder is present in an amount of 0.1% to 5%, expressed as percentage of the
solids level
content in the finished non-woven fabric.
Preferably, the staple fibres are not cellulose acetate fibres or cellulose
ester fibres.
According to the present invention in a further aspect there is provided a
tobacco
smoke filter or filter element comprising a filtering material which includes
a nonwoven
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fabric according to the invention.
The present invention will now be illustrated with reference to the following
Examples and the attached drawing in which FIGURE 1 shows a plot of
biodegradability
with time for "Viscose 2" and "Tencel 2", filter rods of the invention,
compared to a known
cellulose acetate filter rod "CA".
Example 1
Small scale wet laid fabrics of about 40 gsm were prepared using a Handsheet
Former in accordance with TAPPI standard T205. A fibre blend of 90% PVOH fibre
(2.8dtex, 4mm length) and 10% woodpulp was used. The tensile strength of these
sheets
was below 10N, i.e. fairly weak. CMC or PVOH water soluble binders were
subsequently
applied to these sheets using a padding machine ¨ the addition of 4% CMC
increased
tensile strength to 65N, whilst addition of 4.5% PVOH increased tensile
strength to 108N.
Thus the addition of liquid-based binders imparts sufficient strength to
enable such fabrics
to be processed on high speed cigarette filter making equipment. These
handsheet fabrics
were subjected to EDANA Standard FG511.1 Tier 1 Dispersability Shake Flask
Test (using
screens of 1.6, 3.15, 6.3 and 12.5 mm aperture) and it was found that over
99.5% passed
through the smallest 1.6mm screen, thereby demonstrating a very high level of
dispersability. It was also observed that the addition of binder to the
untreated sheet
improved the level of dispersability as measured by this test.
Example 1 demonstrates that nonwoven fabrics of the invention are suitable for
use
in tobacco smoke filters and filter elements (according to the invention), and
have excellent
levels of dispersability in cold water meaning they are highly biodegradable.
Example 2
Two types of wet laid fabric (labelled A and B) according to the invention
were prepared
using a pilot scale inclined wire hydroformer. Fabric A used 100% viscose
fibres of length
6mm and linear density 1.7dtex (supplied by Kelheim Fibres GmbH) and fabric B
used
100% tencel fibres of length 6mm and linear density 1.7dtex (supplied by
Lenzing AG). A
1% solution of water soluble CMC binder (Finnfix 700, manufactured by Noviant)
was
applied to both fabrics during manufacture via a curtain coating technique.
Cigarette filters
were then manufactured from both types of fabric using equipment for the
manufacture of
paper-based cigarette filters, as is well-known in the art (see e.g. Example
4). An essential
aspect of this latter process is the longitudinal embossing of the fabric in
order to facilitate
its condensing into a cylindrical rod form. The bulk, tensile and stretch
characteristics of the
fabric are highly important in determining whether it is able to withstand the
embossing
process ¨ e.g. it must not break or block the rollers ¨ and the applicants
surprisingly found
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that both fabrics processed well on the filter-making equipment. The table
below gives test
results for the fabrics and for cigarette filters made from these fabrics.
PARAMETER FABRIC / FILTER 'A' FABRIC /
FILTER '13'
Fabric Weight (gsm) 39.4 36.9
Fabric Weight Variation CYO 0.76 0.88
Tensile Strength - Machine Direction (N) 37.2 32.3
Tensile Strength - Cross Direction (N) 28.5 20.9
Filter Rod Hardness (/0) 89 91
Filter Rod Pressure Drop C/V (%) 2.0 3.2
Filter Rod Weight C/V (%) 0.6 0.7
Filter Hardness (%) 89 91
27mm Filter Tip Pressure Drop (mm Water) 75 70
Filter Tip Tar Retention (/0) 59 57
Tar Retention Paper (Equivalent PD - %) 72 70
tar Retention Cellulose Acetate (Equivalent PD - %) 53 51
The dispersion characteristics of these filters were assessed by placing
filters from
which the plugwrap had been removed in a beaker of cold water. Filters A and B
both
completely dispersed in less than one minute with occasional gentle agitation.
This was
significantly faster than paper filters which showed no sign of dispersion
over the same
time frame. Samples of fabrics A and B were also subjected to EDANA Standard
FG511.1
Tier 1 Dispersability Shake Flask Test (using screens of 1.6, 3.15, 6.3 and
12.5 mm
aperture). It was found that 99% of fabric A and 97% of fabric B passed
through 6.3mm
aperture screens after being subjected to the conditions, indicating a high
level of
dispersability.
Example 2 demonstrates that nonwoven fabrics of the invention are suitable for
use
in tobacco smoke filters and filter elements (according to the invention), and
have excellent
levels of dispersability in cold water meaning they are highly biodegradable.
Comparative Example 3 (not of the Invention)
A further trial was conducted to prepare a third material ("Fabric C") using
the same
equipment and viscose fibres as Fabric A, but using 5% PVOH binder fibres
rather than 1%
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water soluble liquid binder ¨ i.e. it comprised 95% viscose and 5% PVOH fibre.
Fabric C
had a weight of 36gsm, a weight variation of 1.05%, a machine direction
tensile strength of
47N and a cross direction tensile of 33N, which were all close to the values
of Fabrics A
and B. However, the dispersion characteristics of Fabric C were markedly
inferior to those
of Fabrics A and B. There was no sign of rapid dispersion after the tip was
placed in water
and less than 10% passed through a screen of 6.3mm apertures after being
subjected to
the same Shake Flask Test as in Examples 1 and 2.
Comparative Example 3 demonstrates that for rapid dispersion the water soluble
binder should be applied to the nonwoven fabric as a uniform layer (e.g. by
application in
aqueous form), rather than as binder fibres within the nonwoven fabric.
EXAMPLE 4
Two types of wet laid fabric (again labelled A and B) according to the
invention were
prepared using a pilot scale inclined wire hydroformer, as with Example 2.
Fabric A used
100% viscose fibres of length 6mm and linear density 1.7dtex (supplied by
Kelheim Fibres
GmbH) and fabric B used 100% tencel fibres of length 6mm and linear density
1.7dtex
(supplied by Lenzing AG). A 1% solution of CMC binder (Finnfix 700,
manufactured by
Noviant) was applied to both fabrics during manufacture via a curtain coating
technique.
Cigarette filters were then manufactured from both types of fabric using
equipment for the
manufacture of paper-based cigarette filters, as is well-known in the art.
Sample filters were made from a cylindrical rod (of length 15 mm and
circumference
24.50 mm) formed from wet laid fabric A or B according to the method set out
in
GB2075328A.
The wet laid nonwoven fabric is formed on an inclined wire machine as set out
above. The longitudinally advancing finished web of nonwoven fabric is then
longitudinally
advanced between co-operating rolls having circumferentially-extending
corrugations (to
longitudinally emboss the fabric), and thereafter continuously gathered (while
longitudinally
advancing as a nonwoven fabric web) laterally into rod form. The resulting
continuously
produced rod is continuously cut transversely into finite lengths to give the
product filters or
filter rods, by methods which are also known in the art.
The filters/filter rods/filter segments may be included in filter cigarettes
my methods
well known in the art.
EXAMPLE 5
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The Fibre Biodegradability of filters of the invention was compared with known
cellulose acetate filters.
Sample filters according to the invention were made according to the method
set
out in Example 4 above. The "Viscose 2" filter was made from a fabric which
used 100%
viscose fibres of length 6mm and linear density 1.7dtex (supplied by Kelheim
Fibres
GmbH). The "Tencel 2" filter was made from a fabric which used 100% tencel
fibres of
length 6mm and linear density 1.7dtex (supplied by Lenzing AG). A 1% solution
of CMC
binder (Finnfix 700, manufactured by Noviant) was applied to both fabrics
during
manufacture via a curtain coating technique. The filters were then
manufactured from both
types of fabric using equipment for the manufacture of paper-based cigarette
filters, as is
well-known in the art.
The biodegradability was measured according to OECD 301B 'Ready
Biodegradability' method (modified Sturm test) by an independent laboratory.
The test
provides a measure of the biodegradability of a material (expressed as a
percentage) over
a 28 day period. Figure 1 shows the results for the Viscose 2 and Tencel 2
filters
according to the invention compared to 'CA' ¨ standard cellulose acetate
filter rods ¨ when
tested according to this method.
It is clear that the Viscose 2 and Tencel 2 filters (and materials) according
to the
invention degrade faster and more extensively than cellulose acetate.
Moreover, in
accordance with this test, materials can be assigned three levels of
biodegradability as
measured by their biodegradation over a 10 day period. The pass level of
biodegradability
is 'Ready Biodegradability' (gives greater than 60% biodegradability over the
defined 10
day period), but there other lesser levels of biodegradability depending on
the materials
performance in the test, for example 'Ultimate Biodegradability' and 'None'.
The Viscose 2
and Tencel 2 filters according to the invention were all certified as 'Ready
Biodegradability',
whereas 'CA' received the lesser certification of 'Ultimate biodegradability'.
These results confirm that the filters of the invention show superior
biodegradability
compared to cellulose acetate filters (and cellulosic ester filters).
Experiment 6
EP 0709037 refers to the advantages of cellulose ester fibres with modified
cross-section,
e.g. specific X, Y or I shapes. Comparative examples 1-5 therein refer to
fibres with more
regular fibre cross-sections, and are described as having "poor"
disintegratability in
comparison to "excellent" disintegratability from the modified cross-section
fibres.
11
WO 2013/124475 PCT/EP2013/053654
CA 02863465 2014-07-31
The EDANA Flask Shake test (see method described in Example 1) was performed
on a
number of handsheets of the invention, made with viscose fibres of different
cross-sections.
The viscose fibres used were Danufir and 'Galaxy' from Kelheim Fibres, which
have a
round cross-section, and a modified trilobal cross-section, respectively. The
results are
shown in the Table below. The results show that there is little difference
between the
dispersibility of sheets made using round and modified trilobal cross-
sections. This result is
entirely unexpected given the teaching of EP 0709037, which suggests that
(cellulose
ester) fibres with modified cross-section, e.g. specific X, Y or I shapes,
have "excellent"
disintegratability, while fibres with more regular fibre cross-sections have
"poor"
disintegratability. This demonstrates that the biodegradability of the filters
of the invention
which include staple fibres, a small amount of water soluble binder, and
(optionally) a small
amount of wood pulp, is remarkable. Further, these results show that,
surprisingly, in non-
woven fabrics (and filters) of the invention, the shape of the fibre cross
section is irrelevant
with regard to dipersibility.
Handsheet Type Total Fibre removed in Total Fibre removed
in
departing water (%) departing water + that
retained on smallest (1.6mm
Fibre Fibre Cross-
aperture) screen (%)
Composition section
100% Viscose Round 25 >95
+ CMC binder Trilobal 20 >95
100% Viscose Round 5 >95
+ PVOH binder Trilobal 7 >95
12
