U.S. patent application number 11/241978 was filed with the patent office on 2007-04-05 for cigarettes having hollow fibers.
This patent application is currently assigned to Philip Morris USA Inc.. Invention is credited to John Hearn, Ping Li, Firooz Rasouli.
Application Number | 20070074733 11/241978 |
Document ID | / |
Family ID | 37900741 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070074733 |
Kind Code |
A1 |
Rasouli; Firooz ; et
al. |
April 5, 2007 |
Cigarettes having hollow fibers
Abstract
Smoking articles, such as cigarettes and cigarette filters,
methods of manufacturing smoking articles including hollow fibers,
and methods of smoking are provided. In one exemplary embodiment, a
smoking article contains hollow fibers, wherein the hollow fibers
change properties of mainstream tobacco smoke drawn through the
hollow fibers.
Inventors: |
Rasouli; Firooz;
(Midlothian, VA) ; Hearn; John; (Midlothian,
VA) ; Li; Ping; (Glen Allen, VA) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Philip Morris USA Inc.
|
Family ID: |
37900741 |
Appl. No.: |
11/241978 |
Filed: |
October 4, 2005 |
Current U.S.
Class: |
131/231 ;
131/232; 131/345 |
Current CPC
Class: |
A24D 3/04 20130101; A24D
3/048 20130101; A24D 3/065 20130101; B01D 2313/14 20130101; A24D
3/14 20130101; B01D 63/024 20130101; B01D 53/22 20130101 |
Class at
Publication: |
131/231 ;
131/232; 131/345 |
International
Class: |
A24F 19/00 20060101
A24F019/00 |
Claims
1. A cigarette, comprising: a tobacco rod; a filter operative with
the tobacco rod, wherein the filter comprises a bundle of hollow
fibers, wherein the lumens of the hollow fibers are aligned axially
in parallel to one another; and an additive material in
extra-cellular spaces of the hollow fibers, wherein one end of at
least one of the hollow fibers is obstructed.
2. The cigarette of claim 1, wherein the filter further comprises a
plug of fibrous filter material, wherein the plug is located
upstream and/or downstream from the hollow fibers in the
filter.
3. The cigarette of claim 1, wherein the hollow fibers are located
in a cavity of the filter.
4. The cigarette of claim 1, wherein the obstructed end of the at
least one of the hollow fibers comprises a first smoke impermeable
material located within the lumen of the at least one of the hollow
fibers, wherein the impermeable material obstructs airflow through
the obstructed end of the at least one of the hollow fibers.
5. The cigarette of claim 4, wherein the first smoke impermeable
material comprises a polymer or a composite.
6. The cigarette of claim 1, further comprising a second smoke
impermeable material surrounding an upstream or a downstream end of
the bundle of hollow fibers, wherein the second smoke impermeable
material obstructs airflow around the bundle of hollow fibers and
directs airflow into lumens of the bundle of hollow fibers.
7. The cigarette of claim 6, wherein the first smoke impermeable
material comprises a polymer or a composite.
8. The cigarette of claim 1, further comprising an outer layer on
the hollow fibers, wherein the outer layer and the hollow fibers
comprise different materials.
9. The cigarette of claim 8, wherein the outer layer comprises
sugar or pectin.
10. The cigarette of claim 1, wherein the hollow fibers comprise a
polymeric material.
11. The cigarette of claim 1, wherein the hollow fibers comprise
cellulose, modified cellulose, cellulose acetate, polypropylene,
polysulfone, acrylic compounds, silicone rubber, or mixtures or
combinations thereof.
12. The cigarette of claim 1, wherein the additive material
comprises a flavorant, a reagent which chemically reacts with and
selectively separates a gaseous component of a smoke stream, a
surfactant, a solvent, or mixtures or combinations thereof.
13. The cigarette of claim 12, wherein the additive material
comprises menthol.
14. The cigarette of claim 1, wherein the hollow fibers comprise a
bundle of fibers, and wherein the cigarette further comprises a
ring, wherein the ring surrounds the bundle of fibers.
15. The cigarette of claim 1, wherein the hollow fibers comprises a
bundle of fibers, and wherein the cigarette further comprises an
adhesive, wherein the adhesive bonds walls of the bundle of fibers
to other walls of the bundle of fibers.
16. The cigarette of claim 1, wherein each of the hollow fibers has
a lumen diameter of approximately 50 microns to approximately 1500
microns.
17. The cigarette of claim 1, wherein each of the hollow fibers has
a lumen an inner diameter of approximately 90 microns to
approximately 450 microns.
18. The cigarette of claim 1, wherein the filter further comprises
a sorbent.
19. The cigarette of claim 18, wherein the sorbent is located
upstream in the filter from the hollow fibers.
20. The cigarette of claim 1, wherein the lumens of the hollow
fibers are aligned with one another in a direction in which smoke
will travel through the cigarette.
21. A cigarette filter, comprising: hollow fibers; an outer layer
covering an outer region of the hollow fibers; and cellulose
acetate, wherein the hollow fibers and the outer layer are embedded
within the cellulose acetate.
22. The cigarette filter of claim 21, further comprising an
additive material in extra-cellular spaces in the hollow
fibers.
23. The cigarette filter of claim 22, wherein the additive material
comprises a flavorant, a reagent which chemically reacts with and
selectively separates a gaseous component of a smoke stream, a
surfactant, a solvent, or mixtures or combinations thereof.
24. The cigarette filter of claim 22, further comprising a first
smoke impermeable material located between outer surfaces of the
hollow fibers and the inner diameter of the cigarette filter on one
end of at least one of the hollow fibers, and a second smoke
impermeable material located on end portions of lumens of the
hollow fibers at the other end of the hollow fibers.
25. The cigarette filter of claim 22, wherein the outer layer
comprises sugar or pectin.
26. A method of manufacturing a cigarette filter, comprising:
preparing hollow fibers with a smoke impermeable material covering
one end of at least one of the hollow fibers; at least partially
filling extra-cellular spaces within the hollow fibers with an
additive material; and placing the hollow fibers with the smoke
impermeable material and the additive material in a cigarette
filter.
27. The method of claim 26, wherein the at least partially filling
the extra-cellular spaces within the hollow fibers with the
additive material comprises soaking the hollow fibers in the
additive material for a time effective to at least partially fill
the extra-cellular spaces with the additive material.
28. The method of claim 26, further comprising forming an outer
layer on an outer surface of the hollow fibers before placing the
hollow fibers in the cigarette filter.
29. The method of claim 28, wherein the forming of the outer layer
comprises spraying a layer of pectin or sugar on the outer surface
of the hollow fibers.
30. A method of treating mainstream smoke, comprising: drawing
tobacco smoke axially through hollow fibers, wherein the mainstream
tobacco smoke is drawn into an open upstream end into lumens of the
hollow fibers and is drawn through permeable walls of the hollow
fibers to a downstream end of a smoking article.
31. A cigarette filter comprising a hollow fiber membrane, wherein
the hollow fiber membrane comprises: hollow fibers; and a smoke
impermeable material, wherein the smoke impermeable material
obstructs a downstream end of a lumen of the hollow fiber.
32. The cigarette filter of claim 31, wherein the hollow fiber
membrane comprises more than one hollow fiber bundled and aligned
in a direction parallel to one another and parallel to an axial
direction of the cigarette filter, and/or wherein the hollow fiber
comprises a porous, permeable material.
33. The cigarette filter of claim 31, further comprising an
additive material in extra-cellular spaces of the hollow
fibers.
34. The cigarette filter of claim 33, wherein the additive material
comprises a flavorant, a reagent which chemically reacts with and
selectively separates a gaseous component of a smoke stream, a
surfactant, a solvent, or mixtures thereof.
Description
BACKGROUND
[0001] A wide variety of materials have been suggested in the art
as filters for tobacco smoke. Such filter materials include cotton,
paper, cellulose, and certain synthetic fibers. These filter
materials are known to remove particulates and condensable
components from tobacco smoke. They have little or no effect in
removing certain gaseous components, e.g., aldehydes, from tobacco
smoke. See for example commonly assigned U.S. Pat. No. 6,209,547,
which is hereby incorporated herein in its entirety for all
purposes.
SUMMARY
[0002] Smoking articles, such as cigarettes and cigarette filters,
and methods of manufacturing smoking articles are provided. In one
exemplary embodiment, a smoking article contains hollow fibers
which affect mainstream tobacco smoke drawn through the smoking
article.
[0003] In another exemplary embodiment, a cigarette, comprising: a
tobacco rod; a filter joined to the tobacco rod, wherein the filter
comprises a bundle of hollow fibers, wherein the lumens of the
hollow fibers are aligned axially in parallel to one another; and
an additive material in extra-cellular spaces of the hollow fibers,
wherein one end of at least one of the hollow fibers is obstructed
is provided.
[0004] In another exemplary embodiment, a cigarette filter,
comprising: hollow fibers; an outer layer covering an outer region
of the hollow fibers; and cellulose acetate, wherein the hollow
fibers and the outer layer are embedded within the cellulose
acetate is provided.
[0005] In another exemplary embodiment, a method of manufacturing a
cigarette filter, comprising: preparing hollow fibers with a smoke
impermeable material covering one end of at least one of the hollow
fibers; at least partially filling extra-cellular spaces within the
hollow fibers with an additive material; and placing the hollow
fibers with the smoke impermeable material and the additive
material in a cigarette filter is provided.
[0006] Also provided is a method of treating mainstream smoke,
comprising: drawing tobacco smoke axially through hollow fibers,
wherein the mainstream tobacco smoke is drawn into an open upstream
end into lumens of the hollow fibers and is drawn through permeable
walls of the hollow fibers to a downstream end of a smoking
article.
[0007] Also provided is a cigarette filter, comprising: a hollow
fiber membrane, wherein the hollow fiber membrane comprises: hollow
fibers; and a smoke impermeable material, wherein the smoke
impermeable material obstructs a downstream end of a lumen of the
hollow fiber.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0008] FIG. 1 illustrates an exemplary embodiment cigarette
including a hollow fiber membrane containing filter, and a path of
fluid flow through the cigarette.
[0009] FIG. 2 illustrates a cross-section of a bundle of aligned
hollow fibers with open upstream ends and impermeable or
semi-permeable material filling gaps between the hollow fibers.
[0010] FIG. 3 illustrates a cross-section of a bundle of aligned
hollow fibers with closed downstream ends and permeable material
filling gaps between the hollow fibers.
[0011] FIG. 4 illustrates another exemplary embodiment cigarette
including a hollow fiber membrane containing filter, and a path of
fluid flow through the cigarette.
[0012] FIG. 5 is an exemplary illustration of a cross-section of a
hollow fiber.
[0013] FIG. 6 is photomicrograph of extra-cellular spaces of an
exemplary hollow fiber.
[0014] FIG. 7 illustrates an exemplary embodiment cigarette
including a hollow fiber membrane and a sorbent in a filter, and a
path of fluid flow through the cigarette.
DETAILED DESCRIPTION
[0015] Smoking articles are provided that include hollow fibers
therein, wherein the hollow fibers are obstructed on one end to
force a fluid through the walls of the hollow fibers.
[0016] As used herein, the term "feed" is used to indicate a
material or fluid which is fed into the hollow fibers. Also as used
herein, the term "retentate" is used to indicate the portion of the
feed which does not pass through the walls of the hollow fibers and
is trapped within or on an outer surface of the lumens of the
hollow fibers. Additionally, the term "filtrate" is used to
indicate the portion of the feed which passes through the walls of
the hollow fibers.
[0017] The term "obstruct" is intended to include blocking, partial
blocking, filtering, or any other means of reducing flow through an
area. For example, an impermeable or semi-permeable material can be
used to obstruct the downstream end of the hollow fibers by
blocking filtrate or feed from passing through a downstream end of
the hollow fibers, or by merely increasing the resistance to flow
for filtrate or feed passing through the downstream end of the
hollow fibers.
[0018] An exemplary use of a cigarette 100 with hollow fibers is
illustrated in FIG. 1, wherein the hollow fibers are utilized as
hollow fiber membranes. As illustrated in FIG. 1, upon lighting a
cigarette 100 at an upstream end 110 of the cigarette 100 and
applying a drawing action to the downstream end 120, a smoke feed
140 (a flow of mainstream tobacco smoke) would travel in a
downstream direction. The smoke feed 140 would pass from the
upstream end 110 through a tobacco rod 50, then through a filter
section 130, then through the downstream end 120 of the cigarette
100.
[0019] Upon entry into the filter section 130, the smoke feed 140
is forced into lumens, or inner diameters, 15 of hollow fibers 10
within the filter section 130. In FIG. 1, the lumens 15 are
unobstructed on the upstream ends 25 of the hollow fibers 10, but
obstructed on the downstream ends 35. The smoke feed 140 passing
into the filter is directed into the upstream ends 25 of the lumens
10 by a first filtrate obstructing or smoke impermeable material 20
(hereinafter "smoke impermeable material" generally), which
obstructs smoke feed 140 flow between the outer circumference of
the bundle of fibers 10 and the inner diameter of the cigarette, as
illustrated in FIG. 1.
[0020] Additionally, the first smoke impermeable material 20 can
also be provided between the individual fibers 10 in the bundle, as
illustrated in FIG. 2, to obstruct fluid flow between the fibers 10
in the bundle. An exemplary cross-section illustration of the first
smoke impermeable material 20 surrounding the hollow fibers 10 in
the bundle, while not obstructing the upstream end 25 of the lumens
15, is illustrated in FIG. 2.
[0021] Next, also as illustrated in FIG. 1, the smoke feed 140 is
forced from the lumens 15 through the walls of the hollow fibers 10
by a second smoke impermeable material, which obstructs the
downstream ends 35 of lumens 15 of the hollow fibers 10. FIG. 3 is
an exemplary cross-section illustration of the second smoke
impermeable material obstructing the downstream ends 35 of the
lumens 15 of the hollow fibers 10.
[0022] It is noted that as illustrated in FIG. 3, the downstream
ends 35 of the hollow fibers 10 can include a filtrate permeable
material 30 between the hollow fibers 10, as well as between the
outer circumference of the bundle of fibers 10 and the inner
diameter of the cigarette filter 130, if desired. As provided
herein, the filtrate permeable material 30 can be any material that
allows filtrate to pass through the filtrate permeable material 30
for ejection out of the downstream end 120 of the cigarette
100.
[0023] The filtrate permeable material 30 can be provided to hold
the hollow fibers 10 in place in relation to one another, as well
as in relation to the filter 130. Alternatively, a ring, an
adhesive, or other physically containing material can be used, as
long as it does not substantially obstruct filtrate flow through
the filter 130. An exemplary embodiment of the filtrate permeable
material 30 is a porous, filtrate permeable material, such as
cellulose acetate.
[0024] By obstructing the downstream ends 35 of the hollow fibers
10, smoke 140 is forced through the walls of the hollow fibers 10
because of the pressure exerted by the smoker on the downstream end
120. By forcing smoke 140 through the hollow fibers 10, the walls
of the hollow fibers 10 can be used to filter smoke 140
therethrough. Thus, the walls of the hollow fibers 10 behave as a
membrane in that the walls of the hollow fibers 10 allow the
filtrate 150 from the smoke 140 to pass, while the retentate (not
shown) is trapped within the lumens 15.
[0025] It is noted that in another exemplary embodiment,
illustrated in FIG. 4, which is similar to FIG. 1, the filter 130
can be reversed. In other words, the first smoke impermeable
material 20 can be formed to obstruct an upstream end 25 of the
lumens 15 so as to not allow smoke to enter the lumens 15 on the
upstream end 25 of the hollow fibers 10. It is noted that the first
smoke impermeable material 20 in FIG. 4 is formed in a similar
fashion to the second smoke impermeable material 35 illustrated in
FIG. 3, wherein the first impermeable material is formed within the
lumens 15 of the upstream end 25 of the hollow fibers.
Additionally, similar to FIG. 3, a filtrate permeable material 30
can also be provided between hollow fibers 10 for the same reasons
as discussed above with respect to FIG. 3.
[0026] Additionally, as also illustrated in FIG. 4, a second smoke
impermeable material 30 can be used to obstruct fluid flow between
the outer circumference of the bundle of hollow fibers 10 and the
inner diameter of the cigarette filter 130, as well as between the
hollow fibers 10, similar to the first smoke impermeable material
20 of the embodiment illustrated in FIG. 1.
[0027] By providing the two smoke impermeable materials 20, 30,
smoke feed 140 can be routed between an outer circumference of the
bundle of fibers 10 and the inner diameter of the cigarette filter
130 at an upstream end 25, through the walls of the hollow fibers
10 and out the downstream end 35. By passing the smoke filtrate 150
through the walls of the hollow fibers 10, the hollow fibers 10
behave as a hollow fiber membrane in that the smoke is separated
into retentate and filtrate 150, wherein the retentate (not shown)
can be trapped on the outer surfaces of the hollow fibers 10. After
passing through the walls of the hollow fibers 10, the filtrate 150
can then be passed through the downstream end 35 of the hollow
fibers 10.
[0028] The hollow fibers 10 used herein are preferably embodied, as
illustrated in FIG. 5, by porous or semi-porous fibers 10 with
lumens 15 (hollow inner diameters) with a wall 18 thickness with at
least some porosity 19. The hollow fibers can be made of any porous
or semi-porous material, wherein the porosity levels can be
tailored to provide predetermined levels of permeability and also
to contain extra-cellular spaces therein. For example, hollow
fibers can be made of polymers, wherein cellulose, modified
cellulose, cellulose acetate, polypropylene, polysulfone, acrylic
compounds and silicone rubber are preferable embodiments. Further
discussion of hollow fiber materials can be found in U.S. Pat. No.
3,708,071, which is hereby incorporated herein in its entirety by
reference for all purposes.
[0029] It is noted that the material used for the hollow fibers 10
can be chosen to have a predetermined pore size by determining the
materials used for the walls. For example, if the hollow fibers 10
are made of larger pore materials, larger constituent filtrates are
allowed to pass through. Thus, the material used for the hollow
fibers 10 can be chosen to selectively restrain passage to only
certain ranges of filtrates, if desired.
[0030] In a preferred smoking article, hollow fibers 10 are
oriented in a direction in which smoke will travel through the
smoking article. By providing such alignment, smoke can travel
through lumens of the hollow fibers in a direction approximately
parallel to the suction or vacuum force applied at the downstream
end of the smoking article drawing smoke from the upstream or lit
end.
[0031] Additionally, the hollow fibers 10 are approximately
parallel to the one another in order to allow smoke feed 140 to
evenly penetrate the hollow fibers 10, pass through the walls of
the hollow fibers evenly, and for fitting bundles of hollow fibers
into the axis of a cigarette. For example, as illustrated in FIG.
1, the axes of the lumens 15 are preferably aligned parallel to one
another (as well as parallel to the axis of the cigarette), wherein
such alignment allows smoke feed 140 to flow through the multiple
lumens directly (i.e., without detour or indirect routing) while
smoking of the cigarette.
[0032] These hollow fibers 10 can be used within any smoking
article, like a traditional or non-traditional cigarette, e.g., in
a cigarette filter. Preferred embodiments provide hollow fibers for
use in smoking articles, such as cigarettes and non-traditional
cigarettes. Non-traditional cigarettes include, by way of example,
cigarettes for electrical smoking systems as described in
commonly-assigned U.S. Pat. Nos. 6,026,820; 5,988,176; 5,915,387;
5,692,526; 5,692,525; 5,666,976; and 5,499,636, the disclosures of
which are hereby incorporated by reference herein in their
entireties.
[0033] Hollow fibers are preferably sized to a length less than the
length of a filter so that the entire length of the fiber can fit
within the area of the filter as the hollow fibers are aligned in
the direction of smoke flow. Also, the diameters of the lumens of
the hollow fibers (in combination with the material used to make
the hollow fibers and the density of any bundle of hollow fibers)
control the amount of flow possible, as well as the force required
to pull the tobacco smoke through the hollow fibers (hereinafter,
resistance to draw (RTD)).
[0034] In addition to using hollow fibers as hollow fiber membranes
to filter materials, such as smoke, therethrough, the hollow fibers
can also be used to provide additives. For example, as illustrated
in FIG. 6, hollow fibers can include porosities (i.e.,
extra-cellular spaces) in the walls of the hollow fibers. Within
these extra-cellular spaces, additive materials can be stored,
wherein the additive materials can be by fluids, such as smoke,
passing through the walls of the hollow fibers and thus through the
extra-cellular spaces.
[0035] The outer diameter and wall thickness of the hollow fibers
are preferably sized to optimize the hollow fibers' ability to hold
additive materials and to control filtrate flow through the walls
and retentate trapping on the walls . It is noted that additive
materials tend not to be absorbed in the lumen of the hollow fibers
due to capillary forces, thus the holding of additive materials is
primarily carried out by the extra-cellular spaces within the
walls. As the outer diameter of the hollow fibers increases, and/or
the number of hollow fibers provided increases, the amount of the
porous spaces within walls of a hollow fiber (i.e., extra-cellular
spaces, such as crack or crevices in walls of hollow fibers) would
tend to increase. By increasing the amount of extra-cellular
spaces, more additive materials can be absorbed. On the other hand,
narrower lumens, and/or fewer hollow fibers can cause the hollow
fibers to hold less additive materials due to their lesser total
outer surface wall areas.
[0036] Preferred embodiment hollow fibers 10 are used to releasably
hold additive materials within the extra-cellular spaces of the
hollow fibers 10. Thus, because of the releasable hold, additive
materials in the hollow fibers 10 can be sufficiently contained to
substantially avoid or minimize unwanted migration of the additive
materials, such as, for example, during storage of the smoking
articles with the additive materials therein.
[0037] In order to provide additive materials in hollow fibers, the
additive materials are provided for absorption or adsorption within
the extra-cellular spaces of the hollow fibers 10. For example,
additive materials can be provided by soaking the hollow fibers 10
in a bath of additive materials, wherein the additive material can
be absorbed into the extra-cellular spaces.
[0038] Therefore, in an average sized cigarette (e.g., a cigarette
with a length between 65-100 mm, a diameter of 6-9 mm and a filter
length of 15-30 mm), the hollow fibers can have a lumen (i.e.,
inner) diameter of approximately 50 microns to approximately 1500
microns (e.g., 50-100, 100-150, 150-250, 350-500, 500-1000, or
1000-1500 microns), preferably approximately 90 microns to
approximately 450 microns. Additionally, the hollow fibers can have
a highly porous wall with a thickness of approximately 10 microns
to 100 microns, preferably approximately 10 to approximately 50
microns, and an outer diameter of approximately 100 microns to
approximately 2100 microns, preferably 100 to approximately 500
microns.
[0039] For example, an exemplary embodiment cigarette can be
designed to include a bundle of 10 to 15 hollow fibers, wherein
each hollow fiber has a lumen diameter of approximately 200
microns, a wall thickness of approximately 50 microns with an outer
diameter of approximately 350 microns.
[0040] Hollow fibers can be made by spinning or other fiber making
techniques. For example, methods of making hollow fibers have been
described in U.S. Pat. Nos. 2,999,296 and 4,234,431, which are
hereby incorporated herein in their entireties by reference.
[0041] In order to use the hollow fibers 10 in a smoking article,
the hollow fibers 10 are cut or otherwise made to a specific
length. The hollow fibers 10 can preferably be used in a
circumferentially spaced relation in a filter section of a smoking
article or can be gathered into a bundle prior to insertion into a
final product. If the hollow fibers are bundled, the hollow fibers
10 can be held together using a permeable, semi-permeable or
impermeable material, as mentioned above, an enclosure, such as a
ring, or an adhesive, such as triacetin, epoxy, and silicone
rubber.
[0042] Additionally, because of the releasable hold, the additive
materials are preferably mobile enough within the extra-cellular
spaces of the hollow fibers to be released therefrom upon demand.
For example, the additive material can preferably be released from
the hollow fibers upon application of a vacuum force or drawing
action as mentioned above.
[0043] Hollow fibers 10 can also be incorporated into a cigarette
filter to provide a means for controlling a resistance to draw
(RTD) in a cigarette. In a preferred embodiment, a cigarette filter
would include hollow fibers 10 therein. By providing hollow fibers
in a cigarette, a cigarette can be provided with as little or as
much resistance to draw as desired.
[0044] Additionally, hollow fibers 10 can be used to supplement or
replace multi-section filter assemblies, which are often more
difficult to manufacture than hollow fibers 10. Thus, hollow fibers
10 in cigarette filters could be used to simplify the manufacturing
process while still providing tailored levels of RTD.
2. Potting Materials
[0045] As mentioned above, first and second filtrate obstructing or
smoke impermeable materials can be used to obstruct smoke flow
through a smoking article as illustrated in FIGS. 1 and 4. These
filtrate obstructing or smoke impermeable materials along with
semi-permeable or permeable material used to hold the hollow fibers
can be generally referred to as "potting material."
[0046] As used herein, "potting material" is intended to include
materials that can be used to hold hollow fibers in place, as well
as materials that can direct feed, filtrate, and retentate flow in,
around and through lumens of the hollow fibers. As such, the
potting material can be made of any non-toxic, permeable,
semi-permeable or impermeable material that can hold the hollow
fibers in a fixed positional relationship with one another (i.e.,
in parallel to one another). Further discussion of hollow fiber
membranes in potting material can be found in U.S. Pat. Nos.
3,228,887, 3,528,553 and 6,685,832, which are hereby incorporated
herein in their entireties by reference.
[0047] Preferably, the potting material is a polymer or a
composite, wherein the material can be selected depending upon the
degree of permeability desired. For potting material used to
obstruct airflow through an end of a hollow fiber, a filtrate
impermeable or semi-permeable potting material may be desired. For
example, epoxy is a filtrate impermeable potting material. On the
other hand, for potting material used to hold the fibers in place,
wherein filtrate obstruction is not desired, a permeable potting
material may be desired. For example, cellulose acetate is a
permeable potting material.
[0048] The potting material can be formed on any portion of the
hollow fibers 10. For example, the potting material can be formed
on a portion or the entirety of the length, the circumference of
the fibers, and/or on ends of the hollow fibers. However, if the
potting material is chosen to obstruct airflow, the potting
material is preferably formed on less than the entire surface of
the hollow fibers, as to allow for at least some filtrate to pass
through walls 18 of the hollow fibers 10.
[0049] Additionally, less than full coverage of the walls 18 of the
hollow fibers 10 can be desired to not completely enclose and
possibly isolate the extra-cellular spaces and additive materials
that can be contained therein. As such, coverage by the potting
material on the hollow fibers 10 is preferably less than 90% of the
wall surface of the hollow fibers 10, and even more preferably,
less than 60% of the wall surface of the hollow fibers 10 (e.g.,
100-90%, 90-80%, 80-70%, 70-60%, 60-50%, 50-40%, 40-30%, 30-20%,
20-10% or 10-0%).
[0050] The potting material can be formed on the hollow fibers in
any manner that provides the airflow controlling properties desired
by the embodiment. For example, methods of forming potting material
on hollow fibers have been discussed in U.S. Pat. Nos. 6,702,561,
6,663,745, 6,623,637 and 5,480,553, which are incorporated herein
in their entireties by reference.
[0051] As mentioned above, the potting material can be made of any
material that can obstruct smoke passage. As such, the potting
material can be made of an impermeable, semi-permeable or permeable
material. If the potting material is a semi-permeable or permeable
material, then the potting material can be used as permeable
barrier and can increase the resistance to airflow
therethrough.
[0052] Therefore, a smoking article can be provided with hollow
fibers in a conformation such that the structure and orientation
for the hollow fibers 10 allows for at least some of the
extra-cellular spaces of hollow fibers 10 to be accessible to
hollow fibers. Additionally, as provided herein, the smoke flow can
still be at least partially directed through the lumens 15 and the
walls 18 of the hollow fibers 10, wherein additive materials in the
extra-cellular spaces can interact with the airflow as it passes
through the walls 18 of the hollow fibers 10.
3. Outer Layer
[0053] The hollow fibers 10 can also include an outer layer
covering or encapsulating the hollow fibers 10 (with additive
material therein, if desired). Preferably, the outer layer is a
solid wall or film, wherein the solid wall or film can be used to
temporarily seal or encapsulate the hollow fibers 10 (and anything
encapsulated within the hollow fibers 10) away from the surrounding
environment.
[0054] Preferably, the outer layer is applied around the outer
surfaces of the hollow fibers 10 such that additive materials added
to the hollow fibers 10 can be sealed within the hollow fibers 10,
and/or within their extra-cellular spaces. Further, the outer layer
is preferably easily frangible and can be ruptured to allow
additive materials to be released from the hollow fibers 10.
[0055] The outer layer can be any frangible material, such as a
polymer, which is capable of both sealing the hollow fibers, as
well as breaking, rupturing or perforating on demand. Preferably,
the outer layer is made of sugar or pectin, which can also be
provided to flavor filtrate, such as smoke filtrate, contacting the
outer layer if desired. The outer layer is preferably used to
immobilize additive materials within the hollow fibers 10, and thus
preferably reduces dissipation of the additive material until the
outer layer is broken, ruptured or perforated.
[0056] Preferably, the outer layer is a frangible thin film. By
providing a frangible thin film, a difference in fluid pressure on
either side of the outer layer and the hollow fiber walls (i.e.,
drawing on a cigarette with hollow fibers and the outer layer
therein) can be sufficient to cause the outer layer to break to
release the additive materials therefrom.
[0057] For example, in a cigarette, an outer layer can be designed
to break when smoke is drawn through the walls of the hollow
fibers, wherein the vacuum pressure of drawing the smoke can cause
the outer layer to break. In other words, when a smoker can puff on
a cigarette causing the outer layer to be broken by the smoke being
drawn through the walls of the hollow fibers and additive materials
can be released into the smoke as it passed through the walls of
the hollow fibers.
[0058] The outer layer can be formed by any method capable of
applying a film that is sufficiently thin to allow vacuum pressure
to rupture the film. Preferably, the outer layer is applied by
spraying a film forming material onto the outer surfaces of hollow
fibers and allowing for the film forming material to solidify into
a film to provide an outer layer.
4. Smoking Articles
[0059] In a preferred embodiment, the hollow fibers 10 are used in
smoking articles, along with sorbents, such as microporous
materials, to filter or remove gas phase constituents from
cigarette smoke. Sorbents (i.e., microporous sorbents) such as an
activated carbon and/or a zeolite sorbent can be used.
[0060] While any suitable material can be used as a sorbent, a
preferred embodiment includes activated carbon. However, sorbents
can hinder a cigarette designer's ability to add materials, such as
volatile flavor components like menthol, as the sorbents can adsorb
and/or absorb migrating volatile compounds during the time between
cigarette manufacture and its being smoked.
[0061] Two problems occur when additive materials, such as volatile
flavor components, are included in smoking articles with sorbents:
first, the additive materials can migrate throughout the smoking
article; and second, the additive materials can be adsorbed or
absorbed by the sorbents. These problems have previously been
addressed by using centrally located flavor elements in commonly
assigned U.S. patent application Ser. No. 2003/0224918, as well as
filters for a smoking article containing a flavored hollow fiber in
U.S. Pat. No. 4,971,078, both of which are incorporated herein in
their entirety by reference.
[0062] When additive materials are sorbed by sorbents, not only can
additive materials be lost, but also the additive materials can
also occupy active sites in the sorbent. If the additive materials
occupy active sites in the sorbent, the ability of the sorbent to
remove targeted gases or constituents from smoke can be
compromised. However, hollow fibers 10 can be used to overcome this
problem by containing and isolating the additive materials from the
sorbent prior to smoking, and therefore avoiding interaction
between the additive materials and the sorbent during storage.
[0063] In a cigarette filter, in addition to the hollow fibers 10
and the sorbent, a molecular sieve material can also be present.
Preferably, the molecular sieve material can be present in
monolithic or particle form sized at about 0.1 mm to 1 mm, and more
preferably 0.3 mm to about 0.9 mm (e.g., 0.3 mm to 0.4 mm, 0.4 mm
to 0.5 mm, 0.5 mm to 0.6 mm, 0.7 mm to 0.8 mm or 0.8 mm to 0.9 mm)
to facilitate processing into cigarette filters so as to achieve a
desirable filter pressure drop or RTD (resistance to draw).
[0064] Various filter constructions known in the art can be used,
in which hollow fibers 10 can be incorporated. Exemplary filter
structures that can be used include, but are not limited to, a mono
filter, a dual filter, a triple filter, a single or multi cavity
filter, a recessed filter, a free-flow filter, combinations thereof
and the like. Filter elements are typically constructed from
cellulose acetate tow or cellulose paper materials.
[0065] The length and pressure drop of the segments in a dual
filter can be adjusted to provide optimal sorption, while
maintaining acceptable draw resistance. Triple filters can include
mouth and smoking material or tobacco side segments, and a middle
segment comprising paper. Cavity filters include two spaced-apart
filter plugs. The filters can also be ventilated and/or comprise
additional sorbents (such as activated carbon), catalysts or other
additives suitable for use in a cigarette filter.
[0066] Additionally, in an exemplary embodiment, a cigarette 100
with a bundle of hollow fibers 10 in the filter 130 can also
include a sorbent 60. For example, as illustrated in FIG. 7, a
cigarette 100 can be provided with a filter 130 which includes
hollow fibers 10 with an additive material, such as a flavorant,
therein and a sorbent upstream 60 (away from the smoker and toward
the tobacco portion 50). As sorbents are typically effective for
adsorbing or absorbing material added, such as a flavorant, placing
the sorbent 60 upstream from the flavorant in the hollow fibers 10
can reduce the level of absorption or adsorption of the flavorant
by the sorbent 60.
[0067] Preferably, the hollow fibers 10 can be located in a portion
of the filter 130 downstream from the sorbent 60 with a section of
filter material 70, such as cellulose acetate, between the two, as
illustrated in FIG. 7. Preferably, the hollow fibers 10 and the
sorbent 60, if provided, would be placed in cavities within a
filter assembly 40. However, both the hollow fibers 10 and the
sorbent 60, if provided, can be placed anywhere within a filter 130
of a smoking article.
[0068] While a preferred filter includes a sorbent and hollow
fibers 10, the hollow fibers 10 can also be used in smoking
articles without a sorbent in the filter, as illustrated in FIGS. 1
and 4. Regardless of the type of article in which the hollow fibers
10 is incorporated, the hollow fibers 10 can be used to provide
effective containment and delivery of materials, such as volatile
flavors or other smoking related chemicals.
5. Additives
[0069] Hollow fibers can desirably be used to encapsulate additives
in a smoking article, as mentioned above, wherein additives can be
encapsulated within extra-cellular spaces of the hollow fibers. By
such encapsulation, additives can both be protected from loss and
can be mixed with entrainment air as air passes through the walls
of the hollow fibers.
[0070] In order to immobilize or encapsulate additives within
hollow fibers 10, hollow fibers 10 are preferably soaked in
additives. Soaking allows the additives to be absorbed into
extra-cellular spaces 35 of hollow fibers 10, where the additives
can remain due to capillary forces, thus preventing dissipation of
the additives.
[0071] The hollow fibers 10 can preferably be placed in a smoking
article, more preferably a cigarette filter, where the hollow
fibers 10 are aligned in a cigarette for airflow. For example, the
long axes of the hollow fibers 10 can be aligned with the long axis
of the cigarette for airflow purposes. Also, a downstream potting
material 30 can be used to obstruct fluid flow through the
downstream end of the hollow fibers 10.
[0072] Additionally, an outer layer can be formed on the hollow
fibers 10 in order to prevent dissipation and to further
encapsulate additive materials in extra-cellular spaces of the
hollow fibers, as mentioned above.
[0073] The additives can be flavors, which can be selected from any
number of known artificial and natural materials, such as, for
example, peppermint, spearmint, wintergreen, menthol, cinnamon,
chocolate, coffee, tobacco, vanillin, licorice, clove, anise,
sandalwood, geranium, rose oil, vanilla, lemon oil, cassia,
spearmint, fennel, ginger, ethylacetate, isoamylacetate,
propylisobutyrate, isobutylbutyrate, ethylbutyrate, ethylvalerate,
benzylformate, limonene, cymene, pinene, linalool, geraniol,
citronellol, citral, peppermint oil, orange oil, coriander oil,
borneol, fruit extract and the like. Illustrative of such tobacco
flavorants are those described in U.S. Pat. Nos. 3,580,259;
3,625,224; 3,722,516; 3,750,674; 3,879,425; 3,881,025; 3,884,247;
3,890,981; 3,903,900; 3,914,451; 3,915,175; 3,920,027; 3,924,644;
3,966,989; 4,318,417; and the like, which are incorporated herein
by reference in their entirety.
[0074] The additives can also be chemicals, wherein the chemicals
can be used to attract or repel aerosols, or react with smoke
constituents to remove or chemically extract smoke
constituents.
[0075] For example, chemicals which can be used to attract or repel
aerosols include surfactants containing distinct hydrophobic
(apolar) and hydrophilic (polar) regions. For example, polar
surfactants can be used to attract or repel selected tobacco smoke
constituents like polar tobacco constituents due to intrinsic
attractive polarity properties. For example, by attracting tobacco
smoke constituents, these tobacco smoke constituents can be trapped
and held within the hollow fibers chemically (in addition to
mechanically being selectively separated by pore size of the walls
of the hollow fibers, as mentioned above).
[0076] As mentioned above, chemicals or chemical systems can also
be used to react with smoke constituents to remove smoke
constituents. For example, chemical systems such as
aminopropylsilyl (APS), aminoethyl aminopropylsilyl (AEAPS) and
aminoethylaminoethyl aminopropylsilyl (AEAEAPS) can be used. See
commonly assigned U.S. Pat. Nos. 6,595,218 and 6,209,547, both of
which are hereby incorporated herein by reference in their
entirety.
[0077] As mentioned above, chemicals can also be used to react with
smoke constituents to extract smoke constituents. The term
"chemical extractive smoking" is intended to mean providing
predetermined tobacco smoke constituents to a smoker without any
combustion of tobacco (i.e., smokeless smoking).
[0078] Chemical extractive smoking provides a chemical or reagent,
such as water or alcohol, for interaction with tobacco in a tobacco
product. By allowing the chemical or reagent to interact with
tobacco, a tobacco enriched chemical or reagent can be formed,
which in turn can be inhaled as a vapor or aerosol. For example,
the chemical or reagent can be solvents, such as water or alcohol,
such as ethyl alcohol. Preferably, the chemical extractive smoking
occurs at lower than combustion temperatures; however heat can be
utilized to promote vaporization (or volatilization) of the tobacco
enriched chemical or reagent.
[0079] However, it is noted that heat can be used to increase the
vapor and the solubility of the tobacco constituents for "smoking."
By using heat, the tobacco enriched chemical or reagent can be heat
vaporized and the mobilization of the tobacco properties within the
vapor can potentially be increased.
[0080] As an exemplary embodiment of a chemical extractive smoking
article, a cigarette can be made with hollow fibers including
immobilized chemicals therein. When "smoked," the drawing action on
one side of the hollow fibers 10 releases chemicals into the
tobacco, whereupon the chemicals cause extractive release of a
tobacco aerosol.
[0081] While the invention has been described in detail with
reference to specific embodiments thereof, it will be apparent to
those skilled in the art that various changes and modifications can
be made, and equivalents employed, without departing from the scope
of the appended claims.
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