U.S. patent application number 12/870166 was filed with the patent office on 2010-12-23 for ventilated smoking article.
Invention is credited to Horst Grzonka, Adolf Schluter.
Application Number | 20100319718 12/870166 |
Document ID | / |
Family ID | 8179494 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100319718 |
Kind Code |
A1 |
Schluter; Adolf ; et
al. |
December 23, 2010 |
Ventilated smoking article
Abstract
The invention concerns a smoking article filter plug (16) for a
cigarette, the filter plug being cylindrical and having a plug wrap
(18), grooves (20) being impressed into the plug wrap, and a
tipping paper (22) for the attachment of the filter plug to the
tobacco rod (12). Some grooves are axially extending with respect
to the axis of the filter plug and are open on the side of the
tobacco rod and extend continuously only over a part of the length
of the filter plug. All grooves are covered by a ventilated tipping
paper, which allows ventilating air into the axially extending
grooves only. In addition, the invention concerns the use of such a
filter for the reduction of the CO/tar ratio as a function of the
filter ventilation.
Inventors: |
Schluter; Adolf;
(Eckersdorf, DE) ; Grzonka; Horst; (Mistelgau,
DE) |
Correspondence
Address: |
MIDDLETON & REUTLINGER
2500 BROWN & WILLIAMSON TOWER, (401 S. 4th Street, Suite 2500)
LOUISVILLE
KY
40202
US
|
Family ID: |
8179494 |
Appl. No.: |
12/870166 |
Filed: |
August 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10499281 |
Jun 18, 2004 |
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PCT/GB02/05603 |
Dec 11, 2002 |
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12870166 |
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Current U.S.
Class: |
131/334 ;
131/336 |
Current CPC
Class: |
A24D 3/043 20130101 |
Class at
Publication: |
131/334 ;
131/336 |
International
Class: |
A24D 3/12 20060101
A24D003/12; A24D 1/04 20060101 A24D001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 2001 |
EP |
01129382.6 |
Claims
1. A smoking article incorporating a filter (14) for the reduction
of the CO/tar, ratio delivered during smoking comprising a
cylindrical filter plug (16) of filtration material; a plug wrap of
air-impermeable material (18) around the filter plug (16); the
filter comprising a first section having circumferentially spaced
grooves (20) extending longitudinally along the first section of
the filter plug (16) and also impressed into the plug wrap (18);
and a ventilated tipping paper, connecting the filter plug (16) to
a tobacco rod (12); and all of said grooves (20) being open to the
tobacco rod (12) of said smoking article and extending continuously
only over about 60% of the length of the filter plug (16) and
separated from the mouth end of the filter (16); and wherein all
grooves (20) are covered with the ventilated tipping paper (22)
such that ventilating air entering said grooves (20) through said
ventilated tipping paper (22) flows toward the tobacco rod and into
said filter plug during smoking, wherein the grooves (20) do not
connect with each other, the filter further comprising a second
section aligned with the first and receiving air from the first
section during smoking, wherein the second section comprises
particles of activated carbon, and the first section does not
contain particles of activated carbon.
2. A smoking article in accordance with claim 1, wherein the
filtration material of filter plug (16) is homogeneous over the
full length of the first section of the filter plug (16).
3. A smoking article in accordance with claim 1, wherein two to ten
grooves (20) are provided.
4. A smoking article in accordance with claim 3, wherein three to
five grooves are provided.
5. A smoking article in accordance with claim 4, wherein four
grooves are provided.
6. A smoking article in accordance with claim 1, wherein the
grooves (20) are distributed symmetrically over the circumference
of the filter plug (16).
7. A smoking article in accordance with claim 1 wherein the grooves
(20) are V-shaped or U-shaped.
8. A smoking article in accordance with claim 1, wherein the
grooves have a depth from 0.5 to 2 mm.
9. A smoking article in accordance with claim 1, wherein the
grooves (20) at the circumference have a width of 1 to 3 mm.
10. A smoking article in accordance with claim 9, wherein the
grooves (20) at the circumference have a width of from 1.5 to 2.5
mm.
11. A smoking article in accordance with claim 1, wherein the
filter plug (16) comprises filter tow made of cellulose
acetate.
12. A smoking article in accordance with claim 1, wherein the
filter plug (16) contains additives selected from the group
consisting of activated charcoal, zeolites, Duolite, flavor
modifiers or combinations thereof.
13. A smoking article in accordance with claim 1, wherein the
tipping paper (22) is porous.
14. A smoking article in accordance with claim 1, wherein the
tipping paper (22) is provided with ventilation openings (24) by
mechanical or electrostatic means or by laser beams.
15. A smoking article in accordance with claim 1, wherein the plug
wrap of air-impermeable material is provided with ventilation
openings.
16. A smoking article in accordance with claim 15, wherein the
ventilation openings are provided by on-line machine
perforation.
17. A smoking article in accordance with claim 1, wherein the
degree of ventilation provided to the smoking article by the
tipping paper lies between 30% and 80%.
18. A smoking article in accordance with claim 1 wherein the degree
of ventilation provided to the smoking article by the tipping paper
lies between 40% and 70%.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This current application is a divisional patent application
that claims priority to and benefit from, currently pending, U.S.
patent application Ser. No. 10/499,281, filed on Jun. 18, 2004,
which is a 35 U.S.C. .sctn.371 PCT 30 Month National Stage filing
of PCT/GB02/05603, filed on Dec. 11, 2002, which claims priority to
and benefit from European Patent Application Serial Number EP
01129382.6, filed on Dec. 18, 2001.
DESCRIPTION OF THE INVENTION
[0002] The invention relates to a smoking article, in particular
but not exclusively a cigarette, incorporating a filter in which
grooves are pressed into the circumference of the filter.
[0003] Various forms of embodiment of such filters are known. Thus
U.S. Pat. No. 4,406,294 discloses a cigarette filter with a
cylindrical filter plug, with an air-permeable plug wrap for the
filter plug and with grooves impressed into the circumference of
the filter plug extending over a part of the filter length from the
mouth end of the filter. The grooves are, however, impermeable. The
cylindrical filter plug and hence also the grooves are attached by
an air-permeable tipping paper provided with ventilation openings.
The filter has an uncomplicated structure and achieves an
essentially normal drop in pressure over the cigarette.
[0004] U.S. Pat. No. 4,256,122 discloses a cigarette filter with a
similar structure, where, however, the circumferential surface of
the filter plug, including the walls of the grooves, are
impermeable by virtue of an impermeable plug wrap. Here, though,
some of the grooves are open at the mouth end of the filter plug.
FIGS. 2, 3 and 5 show embodiments which also include grooves which
are still open on the tobacco end. With this filter a strong
tobacco-flavoured cigarette is obtained which retains, the high
reduction of the unwanted smoke constituents and the good
processability on standard cigarette machines. However, some of
these embodiments require precise registration of the perforated
tipping wrapper with circumferential grooves, giving manufacturing
and quality problems.
[0005] U.S. Pat. No. 4,649,943 shows a further modification of such
a filter, in which the grooves are open at the mouth end of the
filter. In addition, at least one perforation is provided in the
area of the grooves intended for the introduction of air through
the plug wrap into the filter plug, thereby providing the filter
with an improved air distribution in the filter rod. In addition a
tipping wrapper of impermeable material which has an air-permeable
region contributes to this. The lining paper (plug wrap) is
impermeable but provided with ventilation openings.
[0006] Further, DE-PS 21 07 850 discloses a filter tip, the
circumference of which is provided with longitudinal grooves. A
plug wrap is not mentioned and the grooves are preferentially open
at the mouth end of the filter.
[0007] U.S. Pat. No. 4,362,171 discloses a cigarette filter with
grooves which are open neither at the tobacco end nor at the mouth
end and thus extend only over the centre of the filter plug. Each
groove is provided with an opening, so that ventilation air is
guided longitudinally along the filter rod in the direction of the
mouth end. Thus outside air is introduced at high velocity in a
simple manner into the cigarette filter, without the danger of a
blockage due to lip pressure and/or a loss of pressure.
[0008] U.S. Pat. No. 4,343,319 discloses a similar cigarette filter
with a smoke-impermeable wrapper for the filter plug and with a
central tube, extending axially through the filter plug, which is
located in flow connection with the opening in the grooves. In this
way the smoke leaving the tobacco rod is divided into two parts.
One part flows through the central pipe and the other part flows
through the filter material. The presence of tubes and
interconnecting passages adds to the complexity of the filter
manufacture.
[0009] Further, a cigarette filter with an air-impermeable wrapper
for the filter core and with grooves in the circumference of the
filter core and which extend over the whole length of the filter
core is disclosed in DE 30 48 905 A1. This filter can be
manufactured more easily, since it is not necessary to change the
production direction.
[0010] A filter for tobacco smoke provided with grooves in its
circumference which are produced by a corrugated material around
the actual filter is known from GB 2102271. The plug wrap
surrounding the filtration material is smoke-impermeable. Grooves
are provided between the plug wrap and the corrugated material, and
also between the tipping wrapper and the corrugated material. The
tipping wrapper is provided with ventilation openings. This filter
element should be versatile and flexibly usable.
[0011] GB 2 089 641 A discloses a filter for a cigarette with a
central, hollow tube, which extends from one end of the filter into
the filter material. The filter core is surrounded by a non-porous
wrapper and the filter plug and the wrapper have at least one
groove, which extends longitudinally from one end of the filter
plug. In this way a normal decrease of pressure through the
cigarette is achieved for a filter with low to moderate efficiency.
Formation of a hollow tube adds to the manufacturing
requirements.
[0012] Further, GB 2 136669 A shows a cigarette filter with a
filter plug which is surrounded by a smoke-permeable material. The
filter has longitudinal corrugations which form grooves outside of
the smoke-permeable wrapper which are open at one end of the filter
and extend in longitudinal direction from this end towards the
other end but not over the entire length of the filter plug. The
smoke permeable wrapper carries means, i.e. a coating, which makes
it smoke-impermeable over a region which extends over only a part
of the length of the grooves and separates from the corresponding
end of the filter a grooved region of the wrapper which is smoke
permeable.
[0013] GB 2 095 093 A discloses a filter with a filter plug with a
non-porous wrapper and with grooves which extend from one end of
the filter a certain distance in the direction of the other end of
the filter. The grooves can be open to the atmosphere and so
aligned that they extend up to the mouth end of the filter or to
the tobacco end of the filter. It is also possible to have an
alternating arrangement of grooves which begin at the mouth end and
at the tobacco end. The filter is fastened to the tobacco rod by a
narrow strip of material in order to prevent disruption of the
entry of the ventilation openings to the grooves.
[0014] U.S. Pat. No. 3,752,165 shows a filter for a smokable
article with a filter plug which is wrapped in a thin, porous
wrapper paper. A plurality of grooves is formed in the wrapper
paper and into the filter material at one end of the filter. The
grooves extend from one end of the filter to a point shortly before
the opposite end and are surrounded by a smoke-impermeable plug
wrap. The grooves extend from one end of the filter to a point
which is some distance from the other end. A high efficiency for
the removal of the tar from the tobacco smoke with an acceptable
decrease of pressure can be achieved with this filter.
[0015] Further, a filter is known from U.S. Pat. No. 3,910,288 with
a filter plug provided around its circumference with grooves which
extend from the tobacco end of the filter up to a place before the
mouth end of the filter. The grooves are formed in a rigid plastic
wrapper which surrounds the filter material. At one end of every
groove an opening is provided which makes a connection to the
filter material possible. Filter ventilation is not provided.
[0016] This filter is very resistant to crushing, so that the
and/or each groove can remain open during the entire smoking of the
smokable article. By gradually changing the portion of the smoke
which flows through the groove from a previously defined value to a
value of 0, the filter achieves an almost homogeneous delivery of
particulate material per puff with a relatively constant increase
of the degree of efficiency of the filter.
[0017] Finally, U.S. Pat. No. 3,596,663 shows a filter for a
smokable article with a filter plug with grooves, the length of
which is not defined. The filter wrapper and the lining paper are
in each case porous and/or provided with perforations. The
air-permeable wrapper is corrugated in order to increase the size
of the air-permeable surface and thus to simplify the path of the
air which is allowed through the ventilated wrapping paper to the
filter material of the filter plug. Thus a ventilated filter is
produced that significantly reduces the restriction of the air
passage to the filtering medium.
[0018] It can thus be stated in summary that for many years
cigarette filters have been provided with grooves which permit
smoke and/or air to be directed differently as a function of the
position and the length of the grooves and the porosity and/or
ventilation of the tipping or filter-wrapping paper. In this way it
is possible to achieve a dilution of the smoke, turbulence of the
smoke in the mouth area, and the separate guidance of ventilation
air arid smoke, as well as some other effects.
[0019] In recent years attention has been directed to one smoke
component, i.e. carbon monoxide (CO), for which no effective,
economical filter is yet known. Particularly in view of the new
legal requirements which prescribe a maximum CO quantity in the
tobacco smoke of a cigarette, attempts are being made to reduce the
CO content of the smoke to below a given maximum value.
[0020] The object of the invention is to produce a filter for a
smoking article, in particular a cigarette, which enables an
effective, in particular adjustable, decrease of the CO content of
the smoke compared with other components, such as tar and
nicotine.
[0021] This is achieved in accordance with the invention by the
features of claim 1.
[0022] Appropriate embodiments are defined by the characteristics
of the subordinate claims.
[0023] Due to the flow mechanics in the filter of this invention,
the retention of the filter material is reduced because of the well
known dependency of the linear flow velocity retention decreases
with increasing flow velocity. Due to the fact that the CO level is
not affected by the filtering material, the CO/tar ratio
decreases.
[0024] If an air-impermeable plug wrap is used with the filter in
accordance with invention then the ventilating air flows over the
grooves toward the tobacco rod when smoking the cigarette and from
there back through the filtration material into the mouth of the
smoker.
[0025] As an alternative it is possible to employ a plug wrap which
is inherently porous or ventilated and hence provided with
ventilation openings. Some of the ventilation air then flows
through this path and hence through the permeable plug wrap into
the filter and to the mouth of the smoker. This portion can be
adjusted by appropriate adjustment of the inherent or artificial
porosity of the plug wrap, by which means the pressure drop/smoking
mechanics as well as the CO/tar ratio can also be influenced.
[0026] As a further alternative, porous or ventilated plastic
sheets or foils may be used as plug wrap material.
[0027] The use of on-machine laser perforation of tipping paper and
impermeable plugwrap is particularly useful for low delivery
products with a tar delivery of less than 3 mg, preferably less
than 1 mg. For such low delivery products it may be advantageous to
provide two rows of ventilation holes, one row located above the
axially extending grooves and another row located downstream of
those holes. On-line machine perforation perforates both the plug
wrap and the filtration material underneath, allowing the ingress
of ventilating air thereto. Thus, mixed ventilation occurs, i.e.
through grooves and filtration material.
[0028] Synthetic or thermoformable plugwraps such as those
described in British Patent Nos. 2058543, 2056841 or 2134365 may
also be especially suitable as heat mouldable plug wrap for the
present invention.
[0029] Experiments have shown that the CO/tar ratio attainable
changes as a function of the filter ventilation, i.e. the CO/tar
ratio is reduced by increasing the filter ventilation, providing a
further correcting variable for the CO/tar ratio.
[0030] In a preferred embodiment two to ten grooves are provided,
since the use of only one groove leads to a very asymmetrical
distribution of the ventilation air in the smoke which could impair
smoking enjoyment. More than ten grooves greatly complicate the
production process and also hardly leave enough space for adequate
flow cross-section of the individual grooves. Good results were
achieved with four grooves.
[0031] The grooves have a V-shaped or preferably a U-shaped cross
section, since this has manufacturing and rheological
advantages.
[0032] By choosing the appropriate number of grooves, their
appropriate depth, width and length it is possible to adjust the
filter properties to the target properties of the cigarette to be
produced.
[0033] All conventionally used filter materials may be employed as
filter material where one or several of these materials can be
used. Preferably a conventional filter tow of cellulose acetate is
used. For hardening the filters, conventional techniques are used,
for example adding triacetin or Tegda to the filter tow.
[0034] It is also possible to add additives, such as activated
charcoal, zeolites, flavour modifiers or an ion exchange resin,
such as that known as Duolite (see U.S. Pat. No. 3,716,500 or
3,943,832) which is a porous particulate salt of a weakly basic
anion exchange resin, to the filter in order to reduce other vapour
phase constituents.
[0035] Preferably the filtration material is homogeneous. As used
herein homogeneous as applied to filtration material means there
are no flow openings, tubes or other elements in the filtration
material. A homogeneous filtration material may, though, be
comprised of different filtration materials, such as in differing
filtration sections, should the filter be a multiple filter. A
homogeneous filtration material has benefits of simplicity in
manufacture.
[0036] Preferably the additive is located in a region of the filter
which does not have grooves. This prevents thermal decomposition of
the additive upon moulding to produce the grooves.
[0037] In accordance with a preferred embodiment the grooves extend
over less than 80% of the length of the filter, where good results
were obtained with about 60%.
[0038] The depth of the grooves should be within the range 0.5 to 2
mm, preferably about 1 mm, where suitable flow volumes are
achieved.
[0039] Taking this criterion into consideration the width of the
grooves, measured at the circumference of the filter, should lie
between 1 and 3 mm, preferentially between 1.5 and 2.5 mm.
[0040] The depth of the grooves along the rod axis may not
necessarily be constant it may for example increase towards the
open end, the tobacco side of the filter. The grooves may also be
non-linear, following for example a screwed or helical form around
the filter.
[0041] In some cases it may be necessary that a further groove is
added to the filter, which runs radially around the filter
circumference. This groove shall connect the axial grooves. It is
useful that this radial groove is located directly below the
ventilation zone of the tipping paper, which enhances the
ventilation effect. In cases of larger ventilation zones it may
also be necessary to use two or more radial grooves.
[0042] The filter of this invention may obviously be included as
part of a dual or triple filtering device.
[0043] The tipping paper serving to attach the filter to the
tobacco rod may have a conventional structure, provided that it
permits ventilation. This can be achieved either by use of a
porous, therefore inherently air-permeable tipping paper or by
producing ventilation openings by mechanical or electrostatic means
or using laser beams.
[0044] In order that the invention may be clearly understood and
readily carried into effect, reference will now be made, by way of
example, to the following diagrammatic drawings, in which:
DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 shows a perspective view of a filter attached to a
tobacco rod with partly wrapped tipping paper,
[0046] FIG. 2 shows a curve plotting of the CO/tar ratio as a
function of the filter ventilation for a filter in accordance with
the invention and a comparison filter,
[0047] FIG. 3 shows an embodiment of a filter with particulate
additive therein, and
[0048] FIG. 4 shows another embodiment of a filter with particulate
additive therein.
BRIEF DESCRIPTION OF THE EMBODIMENTS
[0049] FIG. 1 shows a perspective view of a part of a proposed
filter cigarette generally indicated by the reference symbol 10
with a conventional tobacco rod 12 and a filter element 14 appended
to one end of the tobacco rod 12. The filter element 14 consists of
a cylindrical filter plug 16 of cellulose acetate tow as filtration
material, which is homogeneously distributed over the entire volume
of the filter plug 14. Thus, no flow openings, tubes or other means
are provided in the filter plug 16. As used herein `homogeneous` as
applied to filtration material means there are no flow openings,
tubes or other elements in the filtration material. A homogeneous
filtration material may, though, be comprised of different
filtration materials, such as the differing filtration sections
described below with respect to FIG. 4, none of which incorporate
flow openings, tubes, etc.
[0050] The filter plug 16 is covered with a plug wrap 18 which is
air-impermeable, although in other embodiments (not shown) it can
be inherently porous and/or provided with ventilation openings
depending upon requirements, taking account particularly of the
tobacco taste desired.
[0051] Grooves 20 are stamped into the circumference of the filter
element 14, four grooves 20 in the embodiment shown, which are
distributed symmetrically over the circumference of the filter
element 14. The grooves 20 extend up to the tobacco rod end of the
filter element 14, where they are open so that there is a flow
connection between the grooves 20 and the tobacco rod 12.
[0052] The grooves 20 run over the circumference of the filter plug
16 in an axial direction and end at a rheologically adequate
distance from the mouth end of the filter element 14 and hence at a
distance at which neither air nor smoke from the grooves 20 can
directly reach the mouth end of the filter element 14.
[0053] Investigations have shown that the axial length of the
grooves 20 should be less than 80% of the length of the filter plug
14. About 60% is preferred.
[0054] The grooves 20 have a depth of approximately 1.5 mm and a
U-shaped cross section and a width of approximately 2 mm at the
circumference.
[0055] The filter element 14 is surrounded in the usual way by a
tipping paper 22, which is provided in the embodiment shown with
two circumferential parallel rows of ventilation holes 24. A larger
or smaller number of rows of ventilation holes can also be provided
or the tipping paper 22 can be inherently porous. It is only
necessary to ensure that the porosity and/or the number and size of
the ventilation openings 22 ensure the desired degree of
ventilation.
[0056] For the arrangement of the plug wrap 18 there are in
principle two possibilities, i.e. the use of an air-impermeable
paper or an air-permeable paper. In the case of use of an
air-impermeable paper as plug wrap 18, ventilation air flows
through the ventilation openings 24 when smoking the cigarette into
the grooves 20 and then from the grooves 20 toward tobacco rod,
where the direction is reversed and the ventilation air then flows,
together with the smoke from the tobacco rod 12, through the filter
plug 16 into the smoker's mouth.
[0057] If the plug wrap is air-permeable, either inherently porous
or provided with ventilation openings, then an adjustable portion
of ventilation air flows by this flow path through the
air-permeable plug wrap into the filter and to the mouth of the
smoker. This is in addition to the air flowing through the grooves
20. In this way the dilution of the smoke can be adjusted by air
ventilation in two places, i.e. firstly by ventilation through the
tipping paper 22 and along the grooves 20, and secondly by
ventilation air which enters directly through the plug wrap 18 into
the filter plug 16.
[0058] If necessary, further short grooves open only to the mouth
side of the filter 14 can be impressed into the exterior surface of
the tipping paper 22. These have no rheological function, since
they are not connected with the ventilation zone 24, but only alert
the smoker to the presence of grooves in the filter element 14.
[0059] FIG. 2 shows a graph of the effect of the filter ventilation
on the CO/tar ratio with a filter in accordance with the invention
from conventional cellulose acetate filter tow, an air-impermeable
plug wrap and four grooves 20 with the above dimensions, which are
symmetrically distributed over the circumference of the filter plug
16 and which, commencing from the tobacco end, extend over 60% of
the length of the filter element 14.
[0060] In experiments the ventilation of the filter element 14 was
varied, namely from zero to a maximum ventilation degree of 70%.
For products of 3 mg or less it is necessary, in order to obtain
the required ventilation level, to use additional on machine laser
perforation, as well as pre-perforated tipping. This increased
ventilation level also helps reduce cigarette pressure drop. The
reduction in CO/tar ratio obtained is balanced with the level of
ventilation used.
[0061] In FIG. 2 the full circles indicate the measured values for
a conventional filter made from monoacetate filter tow without
grooves, while the squares describe the measured values for a
filter element 14 in accordance with the invention with the
structure and the same dimensions as the comparison filter
described above.
[0062] One can recognize very well that the filter element 14 in
accordance with the invention reduces the CO content of the smoke
relative to the delivered tar and hence the CO/tar ratio from about
1.4 to about 0.7, while through ventilation alone, and hence
without use of grooves, the CO/tar ratio can be lowered to only to
about 1.12.
[0063] Thus the CO/tar ratio can be reduced to below the limit set
by the new regulations with the filter element 14 in accordance
with the invention by the appropriate selection of a suitable
degree of ventilation for the tipping paper 22.
[0064] Additional investigations of cigarettes with filters
according to this invention showed that these results were
confirmed also for different tobacco blends in the tobacco section
of the cigarette. In Tables 1-3 the results are shown for the
tobacco column of three commercially available cigarettes to which
the filter of this invention was added. The corresponding
cigarettes with conventional filters gave tar levels of about 10
mg, 6 mg, and 3 mg respectively. The measurements were done
following DIN and ISO standards.
[0065] The filters used for these measurements had the following
parameters of the grooves: 4 grooves, 17 mm long, about 1.5 mm wide
and 0.5-1 mm deep. The plug wrap was air impermeable and not
additionally ventilated.
[0066] The findings show clearly that the filters of this invention
(named EF) made it possible to produce cigarettes with comparable
pressure drops to the cigarettes with standard filters (named SF)
by adjusting the ventilation level, but with clearly reduced CO/tar
ratios.
TABLE-US-00001 TABLE 1 SF EF EF EF EF EF Pressure drop 72 76 76 74
73 72 filter in mm(H.sub.20) Filter ventilation 22.6 0.0 12.0 51.8
57.2 62.1 tar in mg 10.25 12.4 11.7 8.8 7.2 5.7 CO in mg 11.21 13.3
12.1 6.7 4.5 2.9 Pressure drop 117 137 121 104 93 93 cigarette in
mm(H.sub.20) CO/tar 1.09 1.07 1.03 0.76 0.63 0.51
TABLE-US-00002 TABLE 2 SF EF EF EF EF Pressure drop 108 90 89 91 89
filter in mm(H.sub.20) Filter ventilation 43.0 0.0 50.6 58.3 69.1
tar in mg 5.6 11.4 7.8 6.1 4.3 CO in mg 6.7 13.1 5.8 3.5 1.8
Pressure drop 112 144 114 110 107 cigarette in mm(H.sub.20) CO/tar
1.19 1.15 0.74 0.57 0.42
TABLE-US-00003 TABLE 3 SF EF EF EF EF Pressure drop 124 100 98 99
98 filter in mm(H.sub.20) Filter ventilation 56.7 0.0 45.2 51.1
62.5 tar in mg 3.33 8.8 6.3 5.2 4.4 CO in mg 4.24 11.3 5.4 3.6 2.6
Pressure drop 107 144 125 121 120 cigarette in mm(H.sub.20) CO/tar
1.27 1.28 0.86 0.69 0.59
[0067] FIG. 3 shows in cross section a filter element 14 of the
invention, where like parts are labelled in accordance with FIG. 1,
attached to a tobacco rod 12. The plug wrap 18 used to overlie the
filter plug 16 includes a portion that has particulate activated
carbon adhered thereto in the region 26. Grooves 20 are formed in
the plug wrap 18 after the plug wrap is wrapped around the filter
plug 16. The filter element is thus an integral element.
[0068] An alternative embodiment along the same theme is shown in
FIG. 4. However, in this embodiment the filter element comprises
three sections: a grooved section in which grooves 20 are formed in
the surface thereof, a Dalmatian carbon section 28 comprising
particles of activated carbon dispersed in cellulose acetate tow,
and a conventional cellulose acetate tow section 30. The three
sections may be joined together by one plug wrap which is mouldable
to produce the grooves of the grooved section. Alternatively, the
grooves are formed in the surface of either a self-sustaining
non-wrapped acetate (NWA) section or a plug wrap enwrapping a
cellulose acetate section. The three sections are then aligned
together and then overwrapped with a further plug wrap (not
shown).
[0069] The embodiments of FIGS. 3 and 4 avoid the problem of having
to mould grooves into a filter section containing particulate
matter, during which moulding there may be adverse effects on the
particulate matter if contacted with heating elements. However, it
is possible to thermally form grooves in a carbon-containing
section, particularly if use is made of a thermoformable plugwrap,
and such is an option open to the cigarette designer.
[0070] In addition, the presence of additive material affects other
vapour phase, constitutents and can be particularly advantageous
for the selective removal of some of those compounds on the
Hoffmann analyte list (see Hoffmann, D., Hoffmann, I., "Tobacco
Smoke Components", Beitrage ziir Tabakforschung International 18
(1998) 49).
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