U.S. patent application number 12/735515 was filed with the patent office on 2011-02-03 for tobacco smoke filter.
Invention is credited to Daniel S. Araujo, Paul Francis Clarke.
Application Number | 20110023900 12/735515 |
Document ID | / |
Family ID | 40547459 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110023900 |
Kind Code |
A1 |
Clarke; Paul Francis ; et
al. |
February 3, 2011 |
TOBACCO SMOKE FILTER
Abstract
A tobacco smoke filter or filter element comprising a
cylindrical plug of a substantially homogeneous filtering material
of circumference between 14.0 and 23.2 mm, wherein the
substantially homogeneous filtering material comprises a plurality
of randomly oriented staple fibres.
Inventors: |
Clarke; Paul Francis; (
Northumberland, GB) ; Araujo; Daniel S.; (Alot
Parana, PY) |
Correspondence
Address: |
FLYNN THIEL BOUTELL & TANIS, P.C.
2026 RAMBLING ROAD
KALAMAZOO
MI
49008-1631
US
|
Family ID: |
40547459 |
Appl. No.: |
12/735515 |
Filed: |
January 23, 2009 |
PCT Filed: |
January 23, 2009 |
PCT NO: |
PCT/GB2009/000215 |
371 Date: |
October 12, 2010 |
Current U.S.
Class: |
131/332 ;
131/331; 131/345 |
Current CPC
Class: |
A24D 3/0208 20130101;
A24D 3/04 20130101 |
Class at
Publication: |
131/332 ;
131/331; 131/345 |
International
Class: |
A24D 3/10 20060101
A24D003/10; A24D 3/06 20060101 A24D003/06; A24D 3/08 20060101
A24D003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2008 |
GB |
0801246.0 |
Dec 8, 2008 |
GB |
0822366.1 |
Claims
1. A tobacco smoke filter or filter element comprising a
cylindrical plug of a substantially homogeneous filtering material
of circumference between 14.0 and 23.2 mm, wherein the
substantially homogeneous filtering material comprises a plurality
of randomly oriented staple fibres.
2. A tobacco smoke filter or filter element according to claim 1
wherein the plug of substantially homogeneous filtering material is
of circumference between 16.0 and 23.2 mm.
3. A tobacco smoke filter or filter element according to claim 1
wherein the staple fibres are crimped.
4. A tobacco smoke filter or filter element according to claim 1
wherein the staple fibres are natural and/or synthetic fibres
and/or fibres formed from natural plant material(s).
5. A tobacco smoke filter or filter element according to claim 1
wherein the staple fibres are cellulose acetate fibres or
polypropylene fibres.
6. A tobacco smoke filter or filter element according to claim 1
including two or more types of staple fibres.
7. A tobacco smoke filter or filter element according to claim 1
further comprising a liquid additive or a particulate additive.
8. A tobacco smoke filter or filter element according to claim 1
wherein the staple fibres are of length between 4 mm and 20 mm.
9. A tobacco smoke filter or filter element according to claim 1
wherein the staple fibres are formed from a tow of total denier of
between 14,000 g and 55,000 g per 9,000 m length.
10. A tobacco smoke filter or filter element according to claim 1
including staple fibres which are plasticised.
11. A tobacco smoke filter or filter element according to claim 1
including cellulose acetate staple fibres plasticized with
triacetin, triethyleneglycol diacetate (TEGDA), or polyethylene
glycol (PEG).
12. A tobacco smoke filter or filter element according to claim 1
wherein the circumference of the cylindrical plug is between 16.2
mm and 23.2 mm.
13. A tobacco smoke filter or filter element according to claim 1
further comprising a wrapper or plugwrap.
14. A tobacco smoke filter or filter element according to claim 1
including a particulate additive on the wrapper or plugwrap.
15. A tobacco smoke filter or filter element according to claim 1
further comprising a water soluble binder material.
16. (canceled)
17. A filter cigarette including a filter according to claim 1, or
a filter which includes a filter element, joined to a wrapped
tobacco rod.
18. A multiple rod comprising a plurality of filters or filter
elements according to claim 1 integrally joined end-to-end.
19. Use of a tobacco smoke filter or filter element comprising a
cylindrical plug of a substantially homogeneous filtering material
comprising a plurality of randomly oriented staple fibres for
selectively reducing one or more phenolic compounds in tobacco
smoke.
20. Use of a cylindrical plug of a substantially homogeneous
filtering material comprising a plurality of randomly oriented
stable fibres as, or in the manufacture of, a filter or filter
element having enhanced degradability.
Description
[0001] The present invention relates to filters and filter elements
for smoking articles such as cigarettes, in particular slim
cigarettes.
[0002] Conventional cigarettes have a circumference around 24.5
mm--`slim` cigarettes (circumference around 21-23.2 mm) and
`superslim` cigarettes (circumference around 16-18 mm) are also
known. It is also possible to manufacture cigarettes with even
narrower circumferences, e.g. in the range 14-16 mm, although these
are not generally commercially available. In the context of this
document, the term `slim` should be construed as including all
cigarettes and/or cigarette filters with a circumference between
around 14.0 and 23.2 mm.
[0003] Selective filtration occurs when the yield of selected
chemicals in cigarette smoke is proportionally reduced to a greater
extent than the majority of compounds in smoke (e.g. tar). Phenolic
compounds--for example phenol, cresols, catechol and
resorcinol--are known constituents of cigarette smoke. They are
toxic compounds--in particular, phenol and catechol are included on
the so-called "Hoffmann" list of the most hazardous compounds found
in cigarette smoke. It is considered desirable to potentially
selectively reduce the quantities of these compounds delivered to
the smoker.
[0004] The usual filtering material used in cigarette filters is a
continuous tow of filamentary cellulose acetate plasticised with
triacetin, which is gathered together in rod form to form the
filter or filter element. In such a continuous tow (and in filters
and filter elements formed therefrom) the filaments of cellulose
acetate tow are predominantly aligned in the longitudinal
direction. It is well known that cellulose acetate exhibits a
selective filtering action towards phenolic compounds. A filter for
a "slim" cigarette will naturally include a reduced volume of
cellulose acetate filtering material compared to a standard filter;
any selective filtering effect may be reduced as there is less
material available to act upon a similar quantity of smoke. It is
desirable, therefore, to provide a slim filter which potentially
selectively reduces the quantities of phenolic compounds delivered
to the smoker of a slim cigarette.
[0005] The specification of a filter tow is described in terms of
the denier per filament (dpf); total denier; and the fibre
cross-sectional shape. The filament denier is defined as the weight
in grams of 9000 metres of a single filament; the total denier is
then simply the dpf multiplied by the number of filaments in the
tow. Thus, for example, a 5Y30,000 tow describes a material with a
filament with a dpf of 5 grams per 9000 metres in the shape of a Y,
comprising 6,000 filaments giving a total denier of 30,000 grams
per 9000 metre length. In order to manufacture a standard cellulose
acetate ("monoacetate") cigarette filter having a low circumference
(i.e. a slim monoacetate filter), it is necessary to use a
cellulose acetate tow with a low total denier because there are
limitations on the amount of material than can be packed into the
slim product. It is well known in the industry that low total
denier tows are more expensive (per unit weight) than higher total
denier tows and there is also limited commercial availability of
low total denier tows. It is desirable, therefore, to provide a
slim filter, which can be made from a wider range of total denier
of cellulose acetate tows than conventional slim or superslim
monoacetate filters.
[0006] According to the present invention there is provided a
tobacco smoke filter or filter element comprising a cylindrical
plug of a substantially homogeneous filtering material of
circumference between 14.0 and 23.2 mm (for example, between 16 and
23.2 mm), wherein the substantially homogeneous filtering material
comprises a plurality of randomly oriented staple fibres.
[0007] Herein, the term "substantially homogeneous filtering
material" means a filtering material which has substantially
uniform physical characteristics throughout any cross-section
therethrough.
[0008] Herein, the term "staple fibres" means individual, discrete,
fibres of specific length. The staple fibres may be randomly
oriented with reference to one another. The substantially
homogeneous filtering material may comprise a plurality of randomly
oriented staple fibres wherein a portion of the randomly oriented
staple fibres generally extend transversely to the longitudinal
axis of the cylindrical plug. The substantially homogeneous
filtering material may comprise a plurality of randomly oriented
staple fibres at least 10% (for example, 20%, 30%, 40%, 50%, 60%,
70%, 80% or 90%) of which by weight extend substantially
transversely to the longitudinal axis of the cylindrical plug.
[0009] The term randomly oriented staple fibres means that the
staple fibres are randomly oriented in three dimensions (in the
filter or filter element). The term randomly oriented staple
fibres, herein, is not intended to (and does not) mean a continuous
cellulose acetate tow, the individual strands of which are
predominantly aligned in the longitudinal direction (although it
will be appreciated that staple fibres may be formed from such
tows, as discussed below). The term randomly oriented staple
fibres, herein, is not intended to (and does not) mean a web or
sheet of filtering material which is formed (from e.g. pulp and/or
fibres) and then shaped as a whole or substantially whole web or
sheet into rod form (by e.g. wrapping). The term randomly oriented
staple fibres does not mean a two dimensional paper-like artefact
which is taken up in a roll form. The term randomly oriented staple
fibres, herein, is not intended to (and does not) mean a web or
sheet of filtering material which is formed (from e.g. pulp and/or
fibres) and then shredded and then shaped into rod form. Sheets or
webs may have random orientation in two dimensions but (even when
shredded) undergo processes (such as embossing) so they retain some
integrity when drawn through a filter making machine. Thus, the
fibres in a filter or filter element made from a sheet or web (even
a shredded sheet or web) will be predominantly aligned along the
longitudinal axis of the filter or filter element, and are
therefore not randomly oriented (in three dimensions) staple
fibres.
[0010] The plurality of randomly oriented staple fibres may form a
porous matrix providing a labyrinth of passages--these may act as
passages for smoke when utilised as a cigarette filter. The
applicants have found that the performance of the filter or filter
element of the invention may be comparable to existing products
(e.g. a "monoacetate" product formed of a continuous tow of
longitudinally oriented filaments of cellulose acetate tow
plasticised with triacetin gathered together in rod form), but the
applicants have found that 20-30% less filtering material (e.g.
cellulose acetate) is required when it is used in the form of
randomly oriented staple fibres. In addition to the requirement for
less filtering material per filter, there is the further advantage
that it is possible to use much higher total denier cellulose
acetate tows than for a conventional superslim product. Thus, in
addition to the cost benefits of the weight saving arising due to
the applicant's invention (because less filtering material is
required), the unit cost of the tow used itself may also be
cheaper, because there is no longer the need to use (expensive and
less readily available) low total denier tows.
[0011] The applicants have unexpectedly found that tobacco smoke
filters or filter elements of the invention may provide enhanced
removal of phenols from tobacco smoke (in a slim cigarette),
compared to e.g. a standard monoacetate filter or filter element
(which does not comprise randomly oriented staple fibres). The
unexpected reduction in phenolic compounds by filters and filter
elements of the invention is even more significant when the lower
weight of filtering material (cellulose acetate) is taken into
account. The applicants have also unexpectedly found that tobacco
smoke filter or filter elements of the invention may be more
readily and swiftly degraded under e.g. environmental conditions,
compared to e.g. a standard monoacetate filter or filter
element.
[0012] The staple fibres may be made of filamentary material. The
staple fibres may be crimped, as is well known in the art. The
staple fibres may be, for example, cellulose acetate or
polypropylene fibres. The staple fibres may be made of (or formed
from) a fibre tow, for example cellulose acetate tow, polypropylene
tow. The staple fibres may be, for example, natural and/or
synthetic fibres; fibres formed from natural plant material(s) etc.
The staple fibres may be cellulose pulp fibres (e.g. which have
been fiberized via a hammermill). The staple fibres may be cut
herbs (e.g. cut tobacco leaf), or obtained from reconstituted
tobacco sheet. The staple fibres may impart flavouring and/or
filtration properties to the final product. The staple fibres may
be of substantially the same length (of substantially uniform
length). The staple fibres may be of a variety of different
lengths. The stable fibres may be for example of length between 4
mm and 20 mm, e.g. between 5 mm and 19 mm, e.g. between 6 mm and 18
mm, e.g. between 7 mm and 16 mm. The staple fibres may be made of,
or formed from, a fibre tow, for example cellulose acetate tow, of
total denier of from 14,000 g to 55,000 g per 9,000 m length, e.g.
from 20,000 g to 50,000 g per 9,000 m length, e.g. from 23,000 g to
45,000 g per 9,000 m length, e.g. from 25,000 g to 40,000 g per
9,000 m length.
[0013] The substantially homogeneous filtering material may
optionally include other material, for example a liquid additive
(such as a flavourant, e.g. menthol solution). The substantially
homogeneous filtering material comprising a plurality of randomly
oriented staple fibres may be formed from a plurality of staple
fibres, and may optionally include other material, for example a
plasticiser, a binder material or other additive. The staple fibres
may be bonded to each other (e.g. due to action of a plasticiser)
at a multiplicity of contact points.
[0014] The substantially homogeneous filtering material may
optionally include a binder material. The substantially homogeneous
filtering material may optionally include a water soluble binder
material. Examples of water soluble materials include water soluble
polymer materials such as polyvinyl alcohol, polyvinyl pyrrolidone,
polyvinyl ether, starches, polyethylene glycols and polypropylene
glycols; blends of water soluble binders with plasticisers such as
triacetin; and hot melt water soluble binders in particulate form.
The inclusion of a water soluble binder material may further
enhance the ability of the filter or filter element to be readily
and swiftly degraded e.g. under environmental conditions.
[0015] The filter or filter element may include one or more
particulate additives--e.g. within the body of the filter or filter
element. The (or each) particulate additive may be a powder (e.g.
particles of 50 to 150 .mu.m diameter) or granular (e.g. particles
of 0.15 to 1.0 mm diameter). Examples of suitable particulate
additives include flavourants or sorbents--e.g. activated carbon,
zeolite, ion exchange resin (e.g. a weakly basic anion exchange
resin), sepiolite, silica gel, alumina, molecular sieves,
carbonaceous polymer resins and diatomaceous earths.
[0016] The filter or filter element may include more than one type
of staple fibre. For example, staple fibres which are fibres (of
e.g. cellulose pulp) which have been fiberized via a hammermill may
be included in the filter in addition to (e.g. mixed with) staple
fibres formed from a filamentary tow.
[0017] The staple fibres (e.g. of fibre tow, e.g. cellulose acetate
tow) may be plasticised. In other words, the substantially
homogeneous filtering material may optionally include a
plasticiser. The formation of plasticised tow is well known in the
art. The plasticiser (which plasticises the staple fibres) may be,
for example, triacetin, triethyleneglycol diacetate (TEGDA) or
polyethylene glycol (PEG). The staple fibres may be fibres of
plasticised cellulose acetate tow. The staple fibres may be
cellulose acetate tow which has been plasticised with e.g.
triacetin.
[0018] The circumference of the cylindrical plug may be for example
between 14.0 mm and 23.2 mm, for example between 16 and 23.2 mm,
for example between 16.0 mm and 20 mm, for example between 16.2 mm
and 20 mm, for example between 16.2 mm and 17 mm.
[0019] The plurality of randomly oriented staple fibres may form a
porous matrix providing a labyrinth of passages in the filtering
material. The labyrinth passages may function as passages for smoke
when utilised as a cigarette filter.
[0020] The tobacco smoke filter or filter element may have
substantially uniform physical characteristics throughout any
cross-section thereof, rather than the more uneven structure that
results from formation from a sheet of filter material.
[0021] In filters and filter elements according to aspects of the
invention, the tobacco smoke filtering material may be over wrapped
with a wrapper or plugwrap, for example a wrapper of paper, for
example a wrapper of an air-permeable paper. Particulate additives
such as those discussed above may be applied to the wrapper or
plugwrap surrounding the filter material, for example as described
in GB 2261152.
[0022] According to the invention in a further aspect there is
provided a multiple rod comprising a plurality of filters or filter
elements as described above and/or herein integrally joined
end-to-end in a mirror image relationship.
[0023] A filter element according to the invention may be used as a
segment of a multi-segment slim filter, e.g. a dual, triple, other
multiple filter. Such filters are well known in the art. If the
filter element is used as or in a segment of a multi-segment
filter, it may be used at (or in) the mouth or buccal end segment
of the filter, or as (or in) any other segment of the filter. A
filter element according to the invention may be used on its own
e.g. as a single segment slim filter (e.g. in the same way as a
monoacetate filter). Such filters are well known in the art.
[0024] 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 of
the filter towards 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 wrap exposed] or by a full tipping
overwrap (which engages around the full filter length and the
adjacent end of the tobacco rod). 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.
[0025] According to the invention in a further aspect there is
provided the use of a tobacco smoke filter or filter element
comprising a cylindrical plug of a substantially homogeneous
filtering material comprising a plurality of randomly oriented
staple fibres for selectively reducing one or more phenolic
compounds in tobacco smoke. According to the invention in a further
aspect there is provided the use of a cylindrical plug of a
substantially homogeneous filtering material comprising a plurality
of randomly oriented staple fibres, as, or in the manufacture of, a
filter or filter element for selectively reducing one or more
phenolic compounds in tobacco smoke.
[0026] According to the invention in a further aspect there is
provided the use of a cylindrical plug of a substantially
homogeneous filtering material comprising a plurality of randomly
oriented staple fibres, as, or in the manufacture of, a filter or
filter element having enhanced degradability.
[0027] The present invention will now be illustrated with reference
to the following Examples and the attached drawings in which
[0028] FIG. 1 is a plan view, not to scale, of an individual filter
in an embodiment of the invention; and
[0029] FIG. 2 shows a cross-section of the filter of FIG. 1.
[0030] The filter 1 shown in FIG. 1 includes a porous elongated
cylindrical plug 2 of circumference 16.9 mm and length 27 mm, which
comprises a plurality of randomly oriented individual or staple
filamentary fibres 3 formed from a 5Y30,000 cellulose acetate tow
plasticised with triacetin. As shown in FIGS. 1 and 2 the staple
fibres 3 generally extend transversely to the longitudinal axis of
the element and tie back slightly to form a multiplicity of contact
points at which the staple fibres 3 are bonded to each other. The
bound fibres provide a substantially homogeneous filtering material
which forms the plug 2. The substantially homogeneous filtering
material so-formed may be described as a porous matrix, which
provides a labyrinth of smoke passages when used as a cigarette
filter. The filter element 1 has substantially uniform physical
characteristics throughout the cross-section.
[0031] The filter may be manufactured by known methods, for example
the method disclosed in U.S. Pat. No. 3,552,400. Thus, a raw tow of
the cellulose acetate is passed through a conventional banding
device so as to separate the individual filaments thereof, and a
further conventional banding device, which may be utilised to
spread the tow into a relatively thin filamentary layer. The
filamentary layer is then passed through a conventional
plasticising device wherein a suitable plasticiser (triacetin in
the present example) is sprayed by suitable jets onto one or both
sides of the filamentary layer to form a plasticised tow. A
conventional feeding means such as a pair of rollers is utilised to
deliver the plasticised tow to a processing apparatus for making
staple fibres and forming these into a continuous rod. A suitable
apparatus is described in full detail in U.S. Pat. No. 3,552,400
and shown in FIG. 1 of that document. The plasticised tow is fed
through a funnel to a chopper which severs the continuous tow into
a multiplicity of discrete staple fibres, the length of which
depends upon the relationship between the speed of the chopper and
the rate of the feed of the continuous tow into the chopper. The
staple fibres produced by the chopper are sucked from the chopper
by means of a turbulent air stream which disperses the staple
fibres (and provides or increases their random orientation) and
directs these through a porous frusto-conical screen, the smaller
or outlet end of which feeds onto a moving porous belt. Particulate
or other additives (not shown) may, if desired, be fed into the
turbulent air stream and dispersed throughout the filter material
at this stage. The porous enclosing means is tapered and slows the
speed of the staple fibres passing therethrough, and also tends to
dispose the staple fibres so the length of a portion of fibres is
disposed substantially transversely to the longitudinal axis of the
product filter rod. The staple fibres are fed onto the porous belt,
which moves the fibres longitudinally into a steam treating
chamber. A bore at the entrance to the steam-treating chamber forms
the longitudinal edges of the porous belt about the staple fibres
as the belt and fibres thereon are drawn longitudinally through the
bore. The drawing of the belt around the fibres thus completes the
formation of the staple fibres into a rod surrounded by the porous
belt. Steam is applied to the porous surface of the belt and passes
continuously and directly therethrough to treat the staple fibres
held therein. The bonding constituents of the staple fibres (e.g.
the triacetin) are thus activated by the steam while the fibres are
carried in cylindrical rod shaped form enclosed by the belt. It is
noted that this processing is well known in the art and is
described in the US patent mentioned above. The belt and staple
fibres entrained therein are then drawn through a cooling station
as is also well known in the art and thus the drying and cooling of
the element (and setting of the bonding constituents) takes place
in the cooling station. The cylindrical rod so-formed may be
wrapped in a plugwrap paper (not shown) and sealed with a lap
adhesive by means that are well-known in the prior art. The
resulting dried and cooled continuous cylindrical rod formed of
randomly oriented staple fibres is peeled from the belt as it
leaves the cooling station, [the belt being substantially flattened
and continuously orbited back to a position in the region of the
screen to gather further additional staple fibres from the screen
and draw these into the steam chamber]. The initial continuous
cylindrical rod formed of randomly oriented staple fibres as it
issues continuously from the machine outlet is cut into finite
lengths for subsequent use. It may be severed by cutting means for
example to form single filters (such as filter 1 of FIG. 1) each of
which is then attached to an individual wrapped tobacco rod to form
a filter cigarette, or to form individual filter elements. More
usually, however, the continuously issuing rod is first cut into
double or higher multiple (usually quadruple or sextuple) length
rods of filters 1 (or filter elements) for subsequent use. The
formation of multiple length filters (and their subsequent
incorporation into filter cigarettes) is well known in the art.
EXAMPLE 2
Phenol Reduction
[0032] The following Table 1 compares Sample A, a filter made
according to the method of U.S. Pat. No. 3,552,400, and which
includes a filtering material formed from a plurality of randomly
oriented staple fibres of plasticised cellulose acetate, with a
prior art monoacetate filter of the same dimensions. The hardness
values (defined as the compressed diameter of the filter rod as a
percentage of the initial rod diameter, the compression of the rod
being caused by a known weight applied through a circular foot for
a specific period of time) and pressure drop (PD) (expressed in mm
Water Gauge) were measured for the samples. The yields of phenolic
compounds were measured for all samples smoked under ISO
conditions; cresols are the combined yields of o-, m- and p-cresol,
whilst Di Hydroxy Phenols are the combined yields of Hydroquinone,
Resorcinol and Catechol. The tar yields from the cigarettes were
also measured in order that the changes in the ratios of phenols to
tar could be assessed. The values for Sample A are expressed as a %
value of that for the prior art monoacetate filter (i.e. the value
for the monoacetate filter is taken as 100, and that for Sample A
expressed as a percentage of that value).
TABLE-US-00001 TABLE 1 Parameter Sample A Monoacetate Tow Weight
77.5 100 Rod Hardness 99.9 100 Pressure Drop 100.6 100 Tar yield*
103.1 100 Nicotine yield* 95 100 CO yield* 103.8 100 Phenol yield*
78.1 100 Total Cresols yield* 78.5 100 Di Hydroxy Phenols yield*
95.9 100 Phenol + Cresols** 75.7 100 Di Hydroxy Phenols** (.mu.g
per mg of tar) 92.9 100 Phenol Reduction per unit weight tow 141
100 Total Cresols Reduction per unit weight 145 100 tow *based on
results expressed as "absolute" figures (i.e. mass/cigarette)
**based on results expressed as .mu.g per mg of tar
[0033] As indicated above, it is desirable to reduce the levels of
phenolic compounds in cigarette smoke. It is known that cellulose
acetate exhibits a selective filtration effect towards phenols, so
it would be expected that filters according to the invention which
include randomly oriented staple fibres of cellulose acetate would
be less effective in removing phenols than comparable monoacetate
filters of similar pressure drop and hardness, because the former
contain e.g. 20 to 30% less cellulose acetate. In fact, the results
show that, surprisingly, Sample A gave reduced yields of phenolic
compounds expressed on both an absolute basis and per mg of tar
than an equivalent monoacetate product. The reductions in phenolic
compounds in Sample A are even more significant when the lower
weight of cellulose acetate in Sample A (which includes the
filtering material formed from a plurality of randomly oriented
staple fibres of plasticised cellulose acetate) compared to the
monoacetate product is taken into account (Sample A includes 77.5%
by weight of the amount of tow of the monoacetate filter).
[0034] The results indicate that filters and filter elements of the
invention provide a surprising and marked selective reduction of
phenolic compounds.
EXAMPLE 3
Degradability
[0035] Different types of cigarette filters were placed in wire
mesh cages on a rooftop site and their weights monitored
periodically over a 12-month period. After 12-months, it was found
that the weight of standard monoacetate filters had reduced by
23-30%, whilst the weight of a dimensionally comparable filter
which includes a filtering material formed from a plurality of
randomly oriented staple fibres of plasticised cellulose acetate
had reduced by 46%. This is surprising because it would have been
expected that a similar weight loss would have occurred.
EXAMPLE 3
Type of Tow
[0036] The properties of two superslim multiple filter rods A and B
(each comprising four 27 mm length filters of the invention of
structure similar to the embodiment of FIGS. 1 and 2), and a
comparable standard monoacetate superslim product "Control" are
given below:
TABLE-US-00002 A B `Control` Tow Item 5Y30,000 4.2Y33,000 6Y17,000
Rod Length (mm) 108 108 108 Circumference (mm) 16.9 16.9 16.8 Rod
Weight (g) 0.291 0.281 0.416 Rod Hardness (%) 88 89 91 27 mm Tip
Pressure Drop (mm) 102 100 115 27 mm Tip Tar Retention (%) 29.4
30.5 33.6 27 mm Tip Nicotine Retn (%) 27.1 29.7 29.3
[0037] The tows used in samples A and B are the same as those used
in any standard (c. 24.5 mm) circumference product; whereas the
above monoacetate control superslim sample required a more
expensive low total denier tow. This example illustrates that
filters of the invention provide acceptable characteristics using
much higher total denier cellulose tows than for a conventional
superslim product.
* * * * *