U.S. patent application number 12/577039 was filed with the patent office on 2011-04-14 for cigarette filter to reduce smoke deliveries in later puffs.
This patent application is currently assigned to Philip Morris USA Inc.. Invention is credited to Mike Braunshteyn, Roland W. Dwyer, Richard Jupe, San Li, Raquel Olegario.
Application Number | 20110083687 12/577039 |
Document ID | / |
Family ID | 43479473 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110083687 |
Kind Code |
A1 |
Olegario; Raquel ; et
al. |
April 14, 2011 |
CIGARETTE FILTER TO REDUCE SMOKE DELIVERIES IN LATER PUFFS
Abstract
A smoking article having a tobacco rod adapted to produce
mainstream smoke, and a filter having an upstream end portion and a
downstream end portion, and wherein the filter is arranged to
receive mainstream smoke at the upstream end portion. The filter
includes a first filter segment of low particulate efficiency at
the upstream end portion; a channeled flow segment adjacent to the
first filter segment, the channeled flow segment including a flow
channel establishing a substantial portion of a predetermined
resistance to draw of the smoking article; a mouthpiece filter
segment of low particulate efficiency at the downstream end
portion; and a tubular body segment at least partially defining a
portion of a cavity between the mouthpiece filter and the channeled
flow segment. Tipping paper attaches the filter with the tobacco
rod and includes an air-admissible ventilation zone at a location
along the tubular body segment.
Inventors: |
Olegario; Raquel; (Richmond,
VA) ; Li; San; (Midlothian, VA) ; Braunshteyn;
Mike; (Richmond, VA) ; Dwyer; Roland W.;
(Richmond, VA) ; Jupe; Richard; (Richmond,
VA) |
Assignee: |
Philip Morris USA Inc.
Richmond
VA
|
Family ID: |
43479473 |
Appl. No.: |
12/577039 |
Filed: |
October 9, 2009 |
Current U.S.
Class: |
131/328 ;
131/200 |
Current CPC
Class: |
A24D 3/045 20130101;
A24D 3/043 20130101 |
Class at
Publication: |
131/328 ;
131/200 |
International
Class: |
A24D 1/04 20060101
A24D001/04 |
Claims
1. A smoking article comprising: a tobacco rod adapted to produce
mainstream smoke; a filter having an upstream end portion and a
downstream end portion, the filter arranged to receive mainstream
smoke at the upstream end portion, the filter comprising: a first
filter segment of low particulate efficiency at the upstream end
portion; a channeled flow segment at a location downstream of the
first filter segment, the channeled flow segment including a flow
channel establishing a substantial portion of a predetermined
resistance to draw of the smoking article; a mouthpiece filter
segment of low particulate efficiency at the downstream end
portion; and a tubular body segment at least partially defining a
portion of a cavity between the mouthpiece filter and the flow
channel of the channeled flow segment; and tipping paper attaching
the filter with the tobacco rod and including an air-admissible
ventilation zone at a location along the tubular body segment.
2. The smoking article of claim 1, wherein the channeled flow
segment is spaced from the mouthpiece filter segment by a distance
sufficient to reduce impaction of a mainstream smoke component upon
an upstream end portion of the mouthpiece filter.
3. The smoking article of claim 1, wherein the air-admissible
ventilation zone comprises a row of perforations extending through
the tipping paper and the tubular body segment.
4. The smoking article of claim 1, wherein the ventilation zone is
spaced from the mouthpiece filter segment by a distance sufficient
to promote mixing of air drawn through the ventilation zone and
mainstream smoke drawn from the tobacco rod.
5. The smoking article of claim 1, wherein at least one of the
first filter segment and the mouthpiece filter segments comprises
cellulose acetate tow of low resistance to draw.
6. The smoking article of claim 1, wherein the flow channel is
coaxially positioned within the channeled flow segment.
7. The smoking article of claim 1, wherein the flow channel is in
an outer periphery of the channeled flow segment.
8. The smoking article of claim 1, wherein the flow channel has a
relatively constant diameter extending from an upstream end to a
downstream end of the channeled flow segment.
9. The smoking article of claim 1, wherein the flow channel is a
spiral channel.
10. The smoking article of claim 1, wherein the flow channel
includes a sintered porous plastic.
11. The smoking article of claim 1, wherein the channel flow
segment is a a plate having at least one orifice.
12. The smoking article of claim 11, wherein the plate has a
thickness of less than 2 mm and the at least one orifice has a
diameter of 0.2 mm to 0.6 mm.
13. A filter having an upstream end portion and a downstream end
portion and arranged to receive mainstream smoke at the upstream
end portion, the filter comprising: a first filter segment of low
particulate efficiency at the upstream end portion; a channeled
flow segment at a location downstream of the first filter segment,
the channeled flow segment including a flow channel establishing a
substantial portion of a predetermined resistance to draw of the
smoking article; a mouthpiece filter segment of low particulate
efficiency at the downstream end portion; and a tubular body
segment at least partially defining a portion of a cavity between
the mouthpiece filter and the flow channel of the channeled flow
segment.
14. The filter of claim 13, wherein the channeled flow segment is
spaced from the mouthpiece filter segment by a distance sufficient
to reduce impaction of a mainstream smoke component upon an
upstream end portion of the mouthpiece filter.
15. The filter of claim 13, wherein at least one of the first
filter segment and the mouthpiece filter segments comprises
cellulose acetate tow of low resistance to draw.
16. The filter of claim 13, wherein the flow channel is coaxially
positioned within the channeled flow segment.
17. The filter of claim 13, wherein the flow channel is in an outer
periphery of the channeled flow segment.
18. The filter of claim 13, wherein the flow channel has a
relatively constant diameter extending from an upstream end to a
downstream end of the channeled flow segment.
19. The filter of claim 13, wherein the flow channel is a spiral
channel.
20. The filter of claim 13, wherein the flow channel includes a
sintered porous plastic.
21. A method of reducing total FTC tar delivery of a smoking
article by drawing mainstream smoke during each puff through an
upstream, channeled filter segment and a downstream filter portion
having a ventilation zone, said upstream channeled filter segment
accumulating tar as smoking progresses through a puff count such
that delivered FTC tar is decreased in the later puffs of the puff
counts when compared to a conventional cigarette.
Description
WORKING ENVIRONMENT
[0001] Heretofore, cigarettes with high levels of ventilation have
usually had unacceptably low levels of resistance to draw (RTD)
unless some counter measure was in place to make up for the
shortfall in RTD. In the past, high-density cellulose acetate
filter segments were used to address the short fall. However such
filtered segments tended to reduce tar delivery (FTC), with little
or no effect upon gas phase components of mainstream tobacco smoke,
such as carbon monoxide (CO) and nitrogen oxide (NO). This solution
tended to worsen the CO to tar (FTC) ratios in filtered (FTC tar)
cigarettes.
[0002] Ventilation has a desirable attribute in that, when
operating alone, it will reduce both the particulate phase and the
gas phase of mainstream smoke. However, highly ventilated
cigarettes have drawbacks in resistance to draw (RTD) as previously
discussed. It can be appreciated that with a flow restricting
orifice in the cigarette filter, the mainstream smoke is forced to
flow through the orifice. With the filter ventilation introduced
downstream from this orifice, the ventilation level is dependent on
the overall resistance to draw (RTD) upstream from the ventilation
holes. For a given number of ventilation holes and size, the filter
ventilation level increases as the upstream RTD increases. At a
given filter efficiency, increased filter ventilation reduces the
smoke tar delivery.
[0003] In a conventional filtered cigarette, per puff tar delivery
increases as smoking progresses through the puff count. This is
mainly due to the combination of reduced filtration from the
tobacco rod, re-vaporization of tar build up on the tobacco rod
from previous puff(s), and a decreased filter ventilation
contribution as the puff (char line) progresses and the upstream
RTD reduces. The tar delivery of the last puff could be twice as
much as the first and/or second puffs. Reducing the degree of
change from early to later puffs in principle would permit for a
more consistent sensorial experience, and reducing the total tar
delivery, without significantly affecting the overall smoking
experience.
[0004] Accordingly, it would be desirable for a smoking article to
address the phenomena of inconsistent smoke deliveries from puff to
puff, since it is known that the delivered tar from earlier puffs
is less than the delivery of the later puffs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a cross-sectional view of a smoking article in
accordance with one embodiment.
[0006] FIG. 2 is a cross-sectional view of the smoking article of
FIG. 1 in accordance with another embodiment.
[0007] FIG. 3 is a cross-sectional view of a smoking article in
accordance with another embodiment.
[0008] FIG. 4 is a cross-sectional view of the smoking article of
FIG. 3, in accordance with a further embodiment.
[0009] FIG. 5 is a graph showing the puff by puff total particulate
matter (TPM) deliveries of a conventional cellulose acetate (CA)
filtered cigarette.
DETAILED DESCRIPTION
[0010] In accordance with one embodiment, a channeled flow segment
is designed such that during the process of smoking the cigarette,
the resistance to flow of smoke through a channel within the
segment increases as a result of tar accumulation or build-up
within the channel. The increased resistance, as smoking
progresses, causes the filter ventilation to increase and the
delivered tar is decreased in the later puffs. In accordance with
another embodiment, the increased resistance to draw (RTD) and
filter ventilation during the later puffs can also be designed so
that it is difficult to smoke the last few puffs (where tar per
puff can be twice as much as the first few puffs) thereby reducing
the total tar delivery without significantly impacting the overall
smoking experience. In addition, depending on the size (inner
diameter) and the length of the flow channel, a desired pressure
drop across the segment can be achieved.
[0011] Referring to FIG. 1, a preferred embodiment provides a
smoking article 10 comprising a tobacco rod 20 and a filter 30
connected with the tobacco rod 20 by an outer wrapper or tipping
paper 28. Preferably, the filter 30 comprises a first filter
segment 40 at an upstream portion 32 of the filter 30, a second or
mouthpiece filter segment 50 at downstream end portion 34 of the
filter 30, and a channeled flow segment 60 situated between the
first and mouthpiece filter segments 40, 50. In accordance with a
preferred embodiment, the first and mouthpiece filter segments 40,
50 are low particulate efficiency filter segments constructed from
cellulose acetate tow.
[0012] As shown in FIG. 1, smoking articles 10 in the form of
cigarettes typically include a generally cylindrical rod 20 of
smokable material 22, contained in a circumscribing porous wrapping
material or paper wrapper 24. The rod 20 is typically referred to
as a "tobacco rod" and has a lit end or upstream end 12 and a
downstream or filter end 14. The smokable material 22 is preferably
a shredded tobacco or tobacco cut filler. However, any suitable
smokable material 22 can be used.
[0013] The filter 30 is adjacent to the filter end 14 of the
tobacco rod 20 such that the filter 30 and tobacco rod 20 are
axially aligned in an end-to-end relationship, preferably abutting
one another. The filter 30 preferably has a generally cylindrical
shape, and the diameter thereof is essentially equal to the
diameter of the tobacco rod 20. The ends (i.e., upstream end 16 and
downstream end 18 (i.e., mouth end or buccal end) of the filter 30
are open to permit the passage of air and smoke therethrough.
[0014] The filter 30 is preferably attached to the tobacco rod 20
by an outer wrapper or tipping paper 28, which circumscribes both
the entire length of the filter 30 and an adjacent region of the
tobacco rod 20. The tipping paper 28 is typically a paper like
product; however, any suitable material can be used.
[0015] As shown in FIG. 1, the channeled flow segment 60 is
adjacent to the first filter segment 50. In accordance with a
preferred embodiment, the channeled flow segment 60 including the
flow channel 62 establishes a substantial portion of a
predetermined resistance to draw of the smoking article 10. The
flow channel 62 is preferably coaxially or concentrically
positioned within the channeled flow segment 60. However, in an
alternative embodiment, one or more flow channels 62 can be
positioned on an outer periphery of the channeled flow segment 60.
In accordance with a preferred embodiment, the channeled flow
segment 60 and the flow channel 62 each have a length of about 1 mm
to 15 mm. The flow channel 62 also preferably has a diameter of
approximately .5 mm to 2 mm.
[0016] The channeled flow segment 60 may be constructed of paper, a
plastic or a metal and more preferably made of a paper product or a
biodegradable plastic or other suitable material having
degradability properties. In accordance with a preferred
embodiment, the flow channel 62 is generally straight, having a
relatively constant diameter such that the channel 62 extends in a
continuous direction without bending from an upstream end to a
downstream end of the channeled flow segment 60. Alternatively, the
flow channel can be a spiral channel, or other suitable
configuration.
[0017] In accordance with an embodiment, the flow channel 62 is at
least in part defined by a cylindrical tubular member 48, which is
constructed from a relatively heavy filter plug wrap or paper. The
tubular member 48 preferably extends from an upstream end to a
downstream end of the segment 60.
[0018] It can be appreciated that the channeled flow segment 60 is
preferably sized to contribute sufficient pressure drop such that
the smoking article 10 presents a resistance to draw of at least 50
mm water or greater, and more preferably in the range of 70-120 mm
water. It can be appreciated that as the channeled flow segments 60
becomes clogged, the resistance to draw and/or flow through the
flow channel 62 increases due to the tar build up. Preferably, the
channeled flow segment 60 has a diameter of approximately 7.0 to
8.0 mm, and more preferably approximately 7.4 to 7.8 mm.
[0019] In accordance with one embodiment, a tubular body segment 64
at least partially defining a portion of a cavity 66 is situated
between the mouthpiece filter 50 and the flow channel 62 of the
channeled flow segment 60. The filter 30 can also include a second
upstream tubular body portion (not shown) that spaces the channeled
flow segment 60 a predetermined distance apart from the first
filter segment 40.
[0020] The smoking article 10 also preferably includes a
ventilating zone 70 comprised of a first row (and optionally second
and possibly third rows) of ventilation holes or perforations 72,
each of which extend through the tipping paper 28, the plug wrap 26
and the tubular body segment 64.
[0021] Preferably the ventilating zone 70 is located near or
adjacent to the channeled flow segment 60 so that air drawn through
the ventilation zone 70 is allowed to mix with the mainstream smoke
from the flow channel 62 before arriving at the mouthpiece filter
segment 50. The distance between the ventilating zone 70 and the
mouthpiece filter segment 50 is preferably at least 5 mm and more
preferably in the range of 5-12 mm. In accordance with a preferred
embodiment, the holes or perforations 72 of the ventilating zone 70
achieve a ventilation level of the smoking article 10 of at least
25% and more preferably at least 50% to 90%.
[0022] During an initial puff or puffs, mainstream smoke is drawn
from the lit end through the tobacco rod 20 to the downstream end
of the filter 30, and drawn through the flow channel 62. Thus, by
the time of subsequent puffs on the smoking article 10, the flow
channel 62 is partially blocked. It can be appreciated that the
resistance to draw (RTD) and the flow distribution of the flow
channel 62 can be depend on several factors including the length of
the filter 30 and the flow channel 62, the inner diameter of the
flow channel 62, and the nature or type of filter materials within
the first filter segment 40 and the mouthpiece segment 50.
[0023] The first filter segment 40 and the mouthpiece filter
segment 50 are preferably a starch-based, polypropylene, or
plasticized cellulose acetate tow, filter paper or other suitable
material. The first filter segment 40 and the mouthpiece segment 50
can also be constructed from a gathered web (e.g., polypropylene
web, polyester web, cellulosic web or starch-based web).
[0024] In accordance with a preferred embodiment, as the smoking
progresses, tar gradually builds up inside and at the ends of the
flow channel 62. Resistance to flow through the flow channel 62
increases due to the tar build up as shown in FIG. 2, and as a
consequence the filter ventilation increases and the tar deliveries
decreases in the later puffs. A more consistent puff-by-puff tar
delivery is thus achieved attributable to the lowered delivery of
the later puffs. In addition, the increased filter ventilation
results in a decreased amount of tobacco burnt and smoke
delivered.
[0025] In accordance with an embodiment, the increased resistance
to draw (RTD) and filter ventilation during the later puffs can
also be designed so that it is difficult to smoke the last few
puffs. It is generally accepted that the first few puffs or earlier
puffs are more important in terms of the smoking experience, and
wherein the reduced tar deliveries in the last few puffs from this
novel filter design can have overall tar reduction with minimum
impact on the smoking experience. It can also be appreciated that
the flow channel 62 can be fine tuned to control the tar build up,
by adjusting or changing the size of the channel 62, including the
length and diameter thereof, so that the resistance-to-draw (RTD)
is acceptable and ventilation of the filter 30 achieves desired tar
delivery from the smoking article 10.
[0026] In accordance with another embodiment, the flow channel 62
can include or be coated with a material 49 (FIG. 2) such as a
sintered porous plastic. In accordance with an embodiment, the flow
channel is filled with a sintered porous plastic. It can be
appreciated that sintered porous plastics can allow "dry" air flow
at a given resistance to draw (RTD). Alternatively, at another
given resistance to draw (RTD), due to the capillary action of the
sintered porous plastic materials, the resistance to draw (RTD) can
increase when a "wet" stream is delivered in the flow channel
62.
[0027] In accordance with another embodiment, as shown in FIGS. 3
and 4, the flow channel 60 can be in the form of a thin plate 100
(0.2 mm to 2 mm in thickness) with at least one orifice (or flow
passage) 110 with a diameter of 0.2 mm to 0.6 mm. The number of
orifices 110 is not limited, but preferably the plate 100 has 2-8
orifices, and is mostly determined by the pressure drop introduced
by this thin plate with orifices. The pressure drop is preferably
in the range of 100 to 500 mm water drop. As the smoking
progresses, smoke tar gradually builds up and partially blocks the
orifices 110 which cause pressure drop increase. This pressure drop
increase would force more air flowing through the filter
ventilation holes 72, or ventilation level increases. The increased
filter ventilation will reduce air flowing into the burning coal
and reduce the smoke generated. In other words, the cigarette
filter 30 will have lower ventilation in the earlier puffs and
higher ventilation in later puffs. The net effect of gradual
increase of ventilation as smoking processes is more smoke in the
earlier puffs and less smoke in the latter puffs, resulting more
consistent puff by puff smoke deliveries.
[0028] It is to be appreciated that in all embodiments, the filter
30 may be constructed from simple combining techniques typically
used in the industry for manufacturing cigarettes at high speeds.
Additionally each embodiment includes support about the cavity 66
to provide desired firmness throughout length of the filter 30.
[0029] FIG. 5 shows puff by puff total particulate matter (TPM)
(mg) deliveries of a conventional cellulose acetate filtered
cigarette. In general, smoke tar tracks with smoke total
particulate matter (TPM). As shown in FIG. 5, the average total
particulate matter (TPM) of the first three puffs is 1.0 mg/puff,
and the average of the last three puffs is 1.8 mg/puff. The total
particulate matter (TPM) from the whole cigarette is 11.3 mg, with
a total of 8 puffs. Accordingly, if the total particulate matter
(TPM) from the last three or four puffs of the cigarette are kept
at around 1.0 mg or so per puff, or similar to that of the first
three puffs, as indicated by the dotted line in FIG. 5, the smoking
articles 10 as shown in FIGS. 1-4 are able to deliver 8-9 mg total
particulate matter (TPM) with a smoking experience similar to that
of a 11 mg total particulate matter (TPM) product, at least for the
first half of smoking.
[0030] It will be understood that the foregoing description is of
the preferred embodiments, and is, therefore, merely representative
of the article and methods of manufacturing the same. It can be
appreciated that many variations and modifications of the different
embodiments in light of the above teachings will be readily
apparent to those skilled in the art. Accordingly, the exemplary
embodiments, as well as alternative embodiments, may be made
without departing from the spirit and scope of the articles and
methods as set forth in the attached claims.
* * * * *