U.S. patent application number 11/730297 was filed with the patent office on 2007-10-11 for smoking articles comprising magnetic filter elements.
This patent application is currently assigned to Philip Morris USA Inc.. Invention is credited to Shalva Gedevanishvili.
Application Number | 20070235046 11/730297 |
Document ID | / |
Family ID | 38694282 |
Filed Date | 2007-10-11 |
United States Patent
Application |
20070235046 |
Kind Code |
A1 |
Gedevanishvili; Shalva |
October 11, 2007 |
Smoking articles comprising magnetic filter elements
Abstract
Disclosed is a filter element adapted to be incorporated into a
filter cigarette. The filter element comprises filter material,
particles of a magnetized adsorbent, and at least one magnetic
substrate. During smoking of a cigarette comprising the filter
element, the at least one magnetic substrate can filter (i.e.,
magnetically attract and trap) the magnetized adsorbent particles
or fragments thereof within the filter element.
Inventors: |
Gedevanishvili; Shalva;
(Richmond, VA) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Philip Morris USA Inc.
Richmond
VA
|
Family ID: |
38694282 |
Appl. No.: |
11/730297 |
Filed: |
March 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60787506 |
Mar 31, 2006 |
|
|
|
Current U.S.
Class: |
131/200 ;
131/201; 131/202; 131/331 |
Current CPC
Class: |
A24D 3/046 20130101;
A24D 3/16 20130101 |
Class at
Publication: |
131/200 ;
131/331; 131/201; 131/202 |
International
Class: |
A24D 3/06 20060101
A24D003/06; A24F 1/00 20060101 A24F001/00 |
Claims
1. A filter element adapted to be incorporated into a filter
cigarette, the filter element comprising filter material, particles
of a magnetized adsorbent, and at least one magnetic substrate.
2. The filter element of claim 1, wherein the magnetized adsorbent
comprises particles of a magnetic material incorporated in
particles of an adsorbent material.
3. The filter element of claim 1, wherein the magnetized adsorbent
comprises particles of iron and/or an oxide of iron incorporated in
particles of activated carbon.
4. The filter element of claim 1, wherein the magnetized adsorbent
has an average particle size of less than about 5 mm and the at
least one magnetic substrate has at least one dimension of greater
than about 1 mm or greater than about 2 mm.
5. The filter element of claim 1, wherein the particles of the
magnetized adsorbent are incorporated throughout the filter
material.
6. The filter element of claim 1, wherein the at least one magnetic
substrate is selected from the group consisting of a disc, ring,
cylinder, ribbon, foil, mesh or rod.
7. The filter element of claim 1, wherein the at least one magnetic
substrate consists essentially of a ferrite magnet, a neodymium
iron boron magnet, a samarium cobalt magnet, an aluminum nickel
cobalt magnet or an electromagnet.
8. The filter element of claim 1, wherein the at least one magnetic
substrate has a Curie temperature of at least about 300.degree. C.
and/or a magnetic field strength effective to attract and trap
magnetized adsorbent particles and/or fragments of magnetized
adsorbent particles within the filter element.
9. The filter element of claim 1, wherein the filter material is
wrapped in plug wrap and the at least one magnetic substrate is
disposed on an inner surface of the plug wrap and/or is at least
partially around the filter material.
10. The filter element of claim 1, wherein the at least one
magnetic substrate is incorporated into one or more filter parts
selected from the group consisting of a shaped paper insert, a
plug, a space between plugs, cigarette filter paper, a cellulose
acetate sleeve, a polypropylene sleeve and a free-flow sleeve.
11. A cigarette comprising the filter element of claim 1.
12. The cigarette of claim 11, wherein the at least one magnetic
substrate is adapted to reduce the amount of magnetized adsorbent
particles or fragmented magnetized adsorbent particles entrained in
the mainstream smoke of the cigarette.
13. The cigarette of claim 11, comprising a tobacco rod attached to
the filter element with tipping paper, wherein the at least one
magnetic substrate is incorporated axially between the filter
element and the tobacco rod.
14. The cigarette of claim 13, wherein magnetized adsorbent
particles are incorporated in the tobacco rod and/or the cigarette
paper.
15. The cigarette of claim 11, wherein the magnetized adsorbent
particles and/or the at least one magnetic substrate are adapted to
change the chemical composition of mainstream smoke that flows
through the filter element.
16. The cigarette of claim 11, wherein the magnetized adsorbent
particles are incorporated in the filter element in an amount
effective to catalyze the conversion of carbon monoxide to carbon
dioxide and/or nitric oxide to nitrogen during smoking of the
cigarette.
17. A method of treating mainstream smoke from the cigarette of
claim 11, the method comprising drawing the smoke through the
cigarette wherein the magnetized particles and/or fragments of the
magnetized particles are magnetically attracted to the at least one
magnetic substrate and removed from the mainstream smoke.
18. A method of making a cigarette filter element comprising filter
material, magnetized adsorbent particles and at least one magnetic
substrate, comprising: providing filter material and plug wrap
material; forming the filter material into a filter rod;
incorporating the magnetized adsorbent particles and the at least
one magnetic substrate in and/or on at least one of the filter rod
and the plug wrap material; and wrapping the filter rod in the plug
wrap material to form the filter element.
19. The method of claim 18, wherein the magnetized adsorbent
particles and/or the at least one magnetic substrate are
incorporated in the filter material prior to forming the filter
material into the filter rod.
20. The method of claim 18, comprising forming the at least one
magnetic substrate at least partially around the filter rod prior
to wrapping the filter rod in the plug wrap, and/or incorporating
the at least one magnetic substrate on an interior surface of the
plug wrap prior to wrapping the filter rod in the plug wrap.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. provisional Application No. 60/787,506, filed
on Mar. 31, 2006, the entire content of which is incorporated
herein by reference.
BACKGROUND
[0002] Cigarettes typically comprise filter elements that may have
incorporated therein adsorbent materials such as carbon. Filter
elements adapted to be incorporated in a filter cigarette may
comprise, for example, particles or granules of carbon such as
activated carbon or activated charcoal and/or other adsorbent
materials incorporated within the cellulose acetate tow or in
cavities between cellulose acetate material.
[0003] During smoking of a cigarette, to the extent that adsorbent
particles or fragments of adsorbent particles could possibly be
entrained in mainstream smoke and issue through (i.e., break
through) the mouth end of the cigarette, techniques to reduce the
amount of adsorbent particles in mainstream smoke would be of
interest.
SUMMARY
[0004] Disclosed is a filter element adapted to be incorporated
into a filter cigarette, as well as a cigarette comprising the
filter element. The filter element comprises filter material,
particles of a magnetized adsorbent material, and at least one
magnetic substrate. In a preferred filter element, the particles of
the magnetized adsorbent are incorporated throughout the filter
material.
[0005] The at least one magnetic substrate preferably has a
magnetic field strength effective to attract the magnetized
adsorbent particles and/or fragments of the magnetized adsorbent
particles that are entrained in the mainstream smoke of a
cigarette. Via magnetic attraction, a magnetic substrate can trap
the magnetized adsorbent particles or fragments thereof within the
filter element. Thus, in a cigarette comprising the filter element,
the at least one magnetic substrate can reduce the amount of
magnetized adsorbent particles that issue from the mouth end of the
cigarette during smoking.
[0006] The magnetized adsorbent material comprises particles of a
magnetic material incorporated in particles of an adsorbent
material. An exemplary magnetized adsorbent material comprises
particles of iron and/or an oxide of iron incorporated in particles
of activated carbon. The magnetized adsorbent can have an average
particle size suitable for incorporation in the filter element of a
cigarette (e.g., less than about 5 mm).
[0007] The at least one magnetic substrate, which preferably has at
least one dimension of greater than about 1 mm or greater than
about 2 mm, can be in the shape of beads, a disc, ring, cylinder,
ribbon, foil, mesh or rod. The magnetic substrate can comprise a
permanent magnet or an electromagnet. Preferred magnetic substrates
consist essentially of a ferrite magnet, a neodymium iron boron
magnet, a samarium cobalt magnet, or an aluminum nickel cobalt
magnet, and can have a Curie temperature of at least about
300.degree. C.
[0008] In an exemplary embodiment, the at least one magnetic
substrate can be incorporated at least partially around the filter
material. For example, the at least one magnetic substrate can be
disposed on an inner surface of plug wrap that is used to wrap the
filter material. In a further exemplary embodiment, the at least
one magnetic substrate can be incorporated into one or more filter
parts selected from the group consisting of a shaped paper insert,
a plug, a space between plugs, cigarette filter paper, a cellulose
acetate sleeve, a polypropylene sleeve and a free-flow sleeve. The
magnetized adsorbent particles and/or the at least one magnetic
substrate can be incorporated in the filter material prior to
forming the filter material into the filter rod.
[0009] An exemplary cigarette comprises a tobacco rod wrapped in
cigarette paper, which is attached to the filter element with
tipping paper. The at least one magnetic substrate can be
incorporated axially between the filter element and the tobacco
rod. A cigarette comprising the filter element can further comprise
magnetized adsorbent particles incorporated in the tobacco rod
and/or cigarette paper used to form the cigarette.
[0010] In a preferred cigarette, the magnetized adsorbent particles
and/or the at least one magnetic substrate can change the chemical
composition of mainstream smoke that flows through the filter
element during smoking of the cigarette. In an embodiment, the
magnetized adsorbent particles can adsorb one or more gas-phase
constituents in mainstream smoke. In a further embodiment, the
magnetized adsorbent particles can catalyze the conversion of one
or more gas phase constituents in mainstream smoke. As an example,
in a cigarette comprising the filter element, the magnetic
particles that are incorporated in the magnetized adsorbent
particle can catalyze the conversion of carbon monoxide to carbon
dioxide and/or nitric oxide to nitrogen during smoking of the
cigarette.
[0011] A method of treating cigarette smoke comprises heating or
lighting the cigarette to form smoke and drawing the smoke through
the cigarette wherein the magnetized particles and/or fragments of
the magnetized particles entrained in the smoke are magnetically
attracted to the at least one magnetic substrate and trapped in the
filter element.
[0012] A method of making a filter element comprising filter
material, magnetized adsorbent particles and at least one magnetic
substrate comprises (i) providing filter material and plug wrap
material; (ii) forming the filter material into a filter rod; (iii)
incorporating the magnetized adsorbent particles and the at least
one magnetic substrate in and/or on at least one of the filter rod
and the plug wrap material; and (iv) wrapping the filter rod in the
plug wrap material to form the filter element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view of a cigarette comprising
magnetized adsorbent particles and magnetic beads that are
incorporated throughout the filter material of a filter element of
the cigarette.
[0014] FIG. 2 is a perspective view of a cigarette comprising
magnetized adsorbent particles and magnetic beads that are
incorporated within a filter element as a gas permeable bed.
[0015] FIG. 3 is a perspective view of a cigarette comprising
magnetized adsorbent particles and a magnetic ring that is formed
around a filter rod of the cigarette.
[0016] FIG. 4 is a perspective view of a cigarette comprising
magnetized adsorbent particles and magnetic rods that are
incorporated along a surface of a filter rod of the cigarette.
[0017] FIG. 5 is a perspective view of a cigarette comprising
magnetized adsorbent particles and magnetic rods that are
incorporated axially within a filter rod of the cigarette.
[0018] FIG. 6 is a perspective view of a cigarette comprising
magnetized adsorbent particles and a magnetic mesh that is
incorporated along an outer surface of a filter rod of the
cigarette.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] Disclosed is a filter element adapted to be incorporated
into a filter cigarette. The filter element comprises cigarette
filter material, particles of a magnetized adsorbent material, and
at least one magnetic substrate. During smoking of a cigarette
comprising the filter element, the magnetic substrate can attract
the magnetized adsorbent particles and/or fragments of the
magnetized adsorbent particles and trap the magnetized adsorbent
particles within the filter element.
[0020] The term "magnetic substrate" as used herein refers to a
monolithic magnetic material preferably having at least one
dimension of at least 1 mm. For example, a magnetic substrate can
comprise a length, width, thickness and/or diameter of at least 1
mm. Generally, the field strength of a permanent magnet made from a
particular magnetic material is proportional to the magnet's size
(e.g., volume). Preferred magnetic substrates are sized and shaped
to be effective filters for magnetized adsorbent particles during
smoking of a cigarette comprising the filter element. A magnetic
substrate can have any size and shape suitable for incorporation in
a filter element.
[0021] An exemplary magnetic substrate can comprise one or more
magnetic beads. Preferred magnetic beads can have an average
particle size of greater than 1 mm (e.g., at least 2, 3, 4 or 5
mm). The shape of the magnetic beads can be substantially spherical
or non-spherical. A more preferred magnetic substrate can be in the
shape of a disc, ring, cylinder, ribbon, foil, mesh or rod. In
embodiments where the magnetic substrate is a rod or cylinder,
preferably the length of the rod or cylinder is greater than 4
times its diameter.
[0022] The filter element can comprise a magnetic substrate made
from any magnetic material capable of attracting and trapping
magnetized adsorbent particles. In an exemplary embodiment, the
magnetic material used to form the magnetic substrate is selected
from the group consisting of ferrite magnets (e.g., magnetic
compositions comprising iron oxide and strontium oxide or barium
oxide), neodymium iron boron (NdFeB) magnets, samarium cobalt
magnets (e.g., SmCo.sub.5, Sm.sub.2Co.sub.17, etc.), aluminum
nickel cobalt magnets (e.g., alloys of aluminum, nickel, cobalt and
iron) and mixtures thereof.
[0023] The magnetic substrate can comprise an electromagnet or a
permanent magnet. In embodiments where the magnetic substrate is an
electromagnet, a power supply can be used to delivery an electric
current to the electromagnet in order to magnetize the
electromagnet. The magnetic strength of a permanent magnet can vary
with temperature. Generally, the spontaneous magnetization of a
magnetic material decreases with increasing temperature. The
temperature above which spontaneous magnetization cannot occur in a
magnetic substrate is known as the Curie temperature. Accordingly,
the range of effective filtration temperatures of a magnetic
substrate made from a permanent magnet is below its Curie
temperature. The Curie temperature of neodymium iron boron magnets
is typically in the range of about 300 to 350.degree. C. Samarium
cobalt magnets and aluminum nickel cobalt magnets typically have a
Curie temperature in the range of about 750 to 800.degree. C., and
about 800 to 900.degree. C., respectively. Preferably the magnetic
substrate is made from a material having a Curie temperature
sufficiently high to retain its magnetic properties during the
smoking of a cigarette. In a preferred embodiment, a magnetic
substrate has a Curie temperature of greater than about 300.degree.
C.
[0024] The magnetic substrate can be a sintered material which is a
fully dense monolith or a partially dense monolith. Thus, the
magnetic substrate can comprise a monolith having 100% or less of
its theoretical density (e.g., a magnet that is at least about 50,
60, 70, 80 or 90% dense). An exemplary magnetic substrate can be in
the shape of a fully dense ring or disc of magnetic material, or
the magnetic substrate can be in the shape of a porous (e.g., gas
permeable) ring or disc.
[0025] The filter element is adapted to be incorporated in a filter
cigarette. Cigarette filters are made in a variety of designs.
Typically, cigarette filters comprise four main components: a
filter tow such as a bundle of cellulose acetate fibers or paper
that comprise the bulk of the filter; a plasticizer (i.e., a
softening agent added to bind the filter fibers together into a
continuous filter rod); a plug wrap (i.e., a paper wrapper that is
used to contain the filter material); and an adhesive used to
secure the plug wrap to the continuous filter rod.
[0026] Filter rods for making cigarette filters, which can be
attached to tobacco rods (e.g., attached with tipping paper) to
produce filter cigarettes, can be made by forming a bundle or tow
of filter material into a rod using a rod forming apparatus.
Typically, a filter rod comprises up to thirty thousand filaments
of filter material. A preferred filter material used to form a
filter rod is cellulose acetate, which is a cellulose ester.
Cigarette filter rods can also be made from other cellulose ester
fibers (e.g., cellulose triacetate), regenerated cellulose (e.g.,
rayon), polyamide fibers (e.g., nylon), polyimide fibers, acrylic
fibers, polyester fibers, polycarbonate fibers, polyethylene
fibers, polyvinyl chloride fibers, filamentary polyolefin
materials, polypropylene fibers, wood pulp fibers, cotton, flax,
jute, wool, silk, ramie, protein fibers and paper. Cigarette filter
rods can be formed from combinations of these materials.
[0027] Conventionally, a plasticizer or binder such as triacetin is
added to the tow before it is passed into the rod forming
apparatus. Furthermore, the tow can be spread and fluffed up, or
"bloomed," usually by placing the tow under tension and passing it
over air jets. The bloomed tow can be passed through a funnel or
other constricting device and then through a shaped aperture to
form the filter rod.
[0028] The plasticizer, which can be added to the tow during or
after blooming, can enhance the bonding of the filaments to each
other at their cross-over points when the tow is gathered. Thus,
addition of a plasticizer can increase the firmness of the filter
rod formed from the tow. The plasticizer may also have filtration
properties. The attributes of the finished filter rod (e.g.,
filtration efficiency, firmness, dimensional stability, etc.) can
be improved by curing (e.g., heating) the plasticizer.
[0029] The filter rod can be provided with an outer layer (e.g.,
plug wrap) to maintain its shape. The outer layer can comprise a
wrapping of cigarette paper or other sheet material. A cigarette
wrapper can be any wrapping suitable for surrounding the filter
material, including wrappers containing flax, hemp, kenaf, esparto
grass, rice straw, cellulose and so forth. Optional filler
materials, flavor additives, and burning additives can be included
in the cigarette wrapper. The wrapper can have more than one layer
in cross-section, such as in a bi-layer wrapper as disclosed in
commonly-owned U.S. Pat. No. 5,143,098, the entire content of which
is herein incorporated by reference.
[0030] Various filter constructions can be used to form the filter
element. Exemplary filter structures include, but are not limited
to, a mono filter, a dual filter, a triple filter, a cavity filter,
a recessed filter, a free-flow filter or combinations thereof. Mono
filters typically contain cellulose acetate tow or cellulose paper
materials. Pure mono cellulose filters or paper filters can be
effective filters for tar and/or nicotine, and are typically
readily bio-degradable. Dual filters typically comprise a cellulose
acetate mouth end and a pure cellulose or cellulose acetate
segment. The length and pressure drop of the segments in a dual
filter can be adjusted to provide the desired filtration (i.e.,
adsorption and/or absorption) and resistance to draw (RTD). Triple
filters can include mouth and tobacco side segments, and a middle
segment comprising paper. Cavity filters typically have two
segments, e.g., acetate-acetate, acetate-paper or paper-paper,
separated by a cavity. Recessed filters include an open cavity at
the mouth end. The filter element can be ventilated and/or comprise
flavorants, catalysts or other additives suitable for use in a
filter element.
[0031] The magnetic substrate can be incorporated into the filter
element in a number of ways. The magnetic substrate may be
incorporated into the filter material before, during and/or after
its manufacture into a filter rod. For example, the magnetic
substrate can be incorporated in filter material used to form a
filter rod and/or incorporated in a pre-formed filter rod. A
magnetic substrate can be incorporated into a filter rod such that
the magnetic substrate is substantially surrounded by the filter
material, or, in an alternative embodiment, a magnetic substrate
can be formed wholly or partially around the filter rod. In yet a
further embodiment, a magnetic substrate can be incorporated into a
space or cavity within the filter rod. The at least one magnetic
substrate can be incorporated into one or more cigarette filter
parts selected from the group consisting of a shaped paper insert,
a plug, a space between plugs, cigarette filter paper, a cellulose
acetate sleeve, a polypropylene sleeve, and a free-flow sleeve.
[0032] The filter element can be attached to a tobacco rod to form
a filter cigarette. In production of a cigarette, a cut filler
composition can be combined with other cigarette additives and
provided to a cigarette-making machine to produce a tobacco column,
which is then wrapped in cigarette paper to form a tobacco rod that
is cut into sections, and optionally tipped with a filter. The
resulting cigarettes can be manufactured to desired specifications
using standard or modified cigarette making techniques and
equipment. Cigarettes may range from about 50 mm to about 120 mm in
length. The circumference is typically from about 15 mm to about 30
mm, preferably around 25 mm. The tobacco packing density is
typically between the range of about 100 mg/cm.sup.3 to about 300
mg/cm.sup.3, and preferably 150 mg/cm.sup.3 to about 275
mg/cm.sup.3.
[0033] Tobacco cut filler is normally in the form of shreds or
strands cut into widths ranging from about 1/10 inch to about 1/20
inch or even 1/40 inch. The lengths of the strands range from
between about 0.25 inches to about 3 inches. The cigarettes may
further comprise one or more flavorants or other additives (e.g.,
burn additives, combustion modifying agents, coloring agents,
binders, etc.).
[0034] Any suitable tobacco mixture may be used for the cut filler.
Examples of suitable types of tobacco materials include flue-cured,
Burley, Bright, Md. or Oriental tobaccos, the rare or specialty
tobaccos, and blends thereof. The tobacco material can be provided
in the form of tobacco lamina, processed tobacco materials such as
volume expanded or puffed tobacco, processed tobacco stems such as
cut-rolled or cut-puffed stems, reconstituted tobacco materials, or
blends thereof. The tobacco can also include tobacco
substitutes.
[0035] The term "mainstream" smoke refers to the mixture of gases
passing down the tobacco rod and issuing through the filter end,
i.e., the amount of smoke issuing or drawn from the mouth end of a
cigarette during smoking of the cigarette. The mainstream smoke
contains smoke that is drawn in through both the lighted region, as
well as through the cigarette paper wrapper. The term "side stream"
smoke refers to smoke produced during static burning.
[0036] In a cigarette comprising the filter element, magnetized
adsorbent particles can be filtered from mainstream smoke via
magnetic attraction to the one or more magnetic substrates that are
incorporated in the filter element. By filter is meant that the
magnetic substrate can magnetically attract and trap the magnetized
adsorbent particles and/or fragments of the magnetized adsorbent
particles within the filter element. Preferably, a magnetic
substrate can substantially reduce the amount of magnetized
adsorbent particles (e.g., magnetized activated carbon particles)
issuing from the mouth end of a cigarette during smoking. In a
preferred cigarette, the filter element can reduce the amount
(e.g., by weight) of magnetized adsorbent particles issuing from
the mouth end of the filter during smoking of the cigarette by at
least about 10 wt. % (e.g., at least 20, 30, 40, 50 wt. % or
more).
[0037] In alternate embodiments, the at least one magnetic
substrate can be evenly or unevenly distributed throughout the
filter element. For example, magnetic beads can be more heavily
loaded at the tobacco rod end, mouth end, or in the intermediate
region between the tobacco rod end and the mouth end of a filter
rod. In a preferred example, a magnetic ring can be incorporated at
the mouth end of a filter rod.
[0038] One or more magnetic substrates can be incorporated in a
hollow portion of a cigarette filter element. For example, some
cigarette filters have a plug/space/plug configuration wherein the
plugs comprise a fibrous filter material and the space is simply a
void between two filter plugs. That void can be filled partially or
wholly with one or more magnetic substrates. A packed bed of
magnetic substrates can be incorporated into such a void. For
example, a bed of magnetic beads can be located in a space between
plugs of a standard cellulose acetate filter rod.
[0039] A magnetic substrate or plurality of substrates can be
incorporated in a filter element after the filter rod has been
formed. As an example, a magnetic substrate can be formed around a
pre-formed filter rod. A magnetic ring, for example, can be formed
(e.g., crimped) around a pre-formed filter rod such that the ring
has an outer diameter that is approximately equal to the diameter
of the filter rod. The radial thickness and/or the axial width of a
magnetic ring can range from about 0.05 mm to 1 mm or more. For
example, a magnetic ring can have a thickness and/or a width of at
least about 0.1, 0.2, 0.5, 1 or 2 mm. By way of a further example,
a magnetic substrate can be formed on an exterior surface of a
pre-formed filter rod before the rod is wrapped in cigarette paper
(e.g., plug wrap) to form the filter element. Magnetic rods or
strips, for example, can be arranged axially along an exterior
surface of a filter rod, between the filter rod and the plug wrap
formed around the filter rod.
[0040] In yet a further example, a magnetic substrate in the shape
of a sheet (e.g., magnetic foil) or mesh (e.g., perforated magnetic
foil) can be formed around a filter rod that is in turn wrapped in
cigarette paper (e.g., plug wrap) to form the filter element. The
sheet or mesh can be first combined with the plug wrap to form a
laminate that is wrapped around the filter rod to form the filter
element. An adhesive can be used to secure the magnetic substrate
to the filter rod and/or the plug wrap. Preferably, a magnetic
foil-laminated plug wrap is adapted to be formed around a filter
rod such that the magnetic foil is positioned on the inner surface
of the plug wrap (e.g., in contact with the filter material).
[0041] The magnetic substrate(s), whether blended directly with the
filter material, incorporated as a packed bed, or incorporated
after formation of a filter rod, may be used alone in the filter
element or may be incorporated with other known materials having
gas phase activity such as catalysts, flavorants and the like.
[0042] The size, distribution and position of the at least one
magnetic substrate incorporated in the filter element either by way
of incorporation into and/or around the filter material can be
determined through routine experimentation as a function of, inter
alia, the amount of magnetized adsorbent particles incorporated
within the cigarette, the amount of gas phase constituents to be
removed from the mainstream smoke, and/or the magnetic strength of
the magnetic substrate(s).
[0043] In addition to a magnetic substrate, the filter element
comprises particles of a magnetized adsorbent. Particles of
magnetized adsorbent comprise magnetic particles incorporated in
particles of an adsorbent. By incorporating magnetic particles into
the adsorbent particles, the adsorbent particles can be attracted
and trapped within the filter element by a magnetic substrate.
Typically, prior to incorporating magnetic particles in the
adsorbent particles, the adsorbent particles are non-magnetic.
[0044] The adsorbent particles can comprise any suitable adsorbent
media. Exemplary adsorbents include molecular sieves such as
zeolites, silicas, silicates, aluminas and carbons (e.g., activated
carbon). A preferred adsorbent media is activated carbon. By
"activated carbon" is meant any porous, high surface area form of
carbon. Activated carbon can be derived via thermal treatment of
any suitable carbon source. The activation treatment typically
increases the porosity, and activated carbon can be provided with a
wide range of pore sizes or the pore sizes can be controlled to
provide a desired pore size distribution.
[0045] A particularly preferred activated carbon is commercially
available (e.g., from PICA USA, Inc., Truth or Consequences, N.
Mex.). The activated carbon could also be manufactured via the
carbonization of coconut husk, coal, wood, pitch, peat, cellulose
fibers, lignite and olive pits. Carbonization is usually carried
out at elevated temperatures, e.g., 400-1000.degree. C. in an inert
atmosphere, followed by activation (i.e., calcining) under reducing
or oxidizing conditions. The activated carbon can be in the form of
beads, granules and/or fibers.
[0046] The adsorbent particles can comprise granulated particles
ranging in size from about 100 microns to about 5 mm. For example,
particles of activated carbon can have an average size of from
about 0.2 to 2 mm (e.g., about 200, 500, 1000 or 2000 microns).
[0047] Particles of adsorbent material can have any desired pore
size distribution that comprises pores such as micropores,
mesopores and macropores. The term "microporous" generally refers
to such materials having pore sizes of about 20 Angstroms or less
while the term "mesoporous" generally refers to such materials with
pore sizes of about 20-500 Angstroms. Magnetic particles can be
incorporated into the pores of the adsorbent particles via
impregnation, mechanical mixing, in situ thermal decomposition of
organic precursor materials or other technique.
[0048] The adsorbent particles can be selected to have an
appropriate surface area to preferentially adsorb selected
constituents from cigarette smoke. For example, activated carbon
typically has a surface area greater than about 50 m.sup.2/g (e.g.,
at least about 100, 200, 500, 1000 or 2000 m.sup.2/g). Typically,
the absorptive capacity of the adsorbent particles increases with
increasing surface area. Furthermore, surface area typically
increases with decreasing particle size. When used as cigarette
filter media, however, adsorbent particles having a small particle
size may pack together too densely to permit mainstream smoke to
flow through the filter with desired resistance to draw (RTD)
during smoking. On the other hand, if the particle size is too
large there may be insufficient surface area to accomplish the
desired degree of filtration. Therefore, such factors can be taken
into account in selecting adsorbent particles suitable for
filtration of mainstream and/or sidestream smoke.
[0049] The magnetized adsorbent particles preferably comprise
particles of a magnetic material incorporated in particles of an
adsorbent material. The magnetized adsorbent particles can be
formed by combining adsorbent particles with magnetic particles or
by combining adsorbent particles with a precursor (e.g., a
precursor solution) that can be treated to form magnetic particles
within the pores of the adsorbent particles.
[0050] According to one method, adsorbent particles such as
activated carbon particles may be combined with solid magnetic
particles optionally using a binder to improve the adhesion between
the adsorbent particles and the magnetic particles.
[0051] According to a further method, adsorbent particles can be
immersed in an aqueous or non-aqueous solution comprising a
precursor compound that can be treated with a chemical reagent
and/or with heat to form the magnetic particles. A preferred
precursor compound is an iron salt, which can be treated with a
reducing agent or with heat to form particles of elemental iron
and/or oxides of iron that are magnetic. The precursor can be
incorporated into the adsorbent particles in a single step or in
multiple steps. The adsorbent particles can be provided with a
loading of about 1 to 150% by weight of the magnetic particles.
[0052] The magnetic particles, whether combined with the adsorbent
particles or formed in situ within the adsorbent particles via the
decomposition of a precursor compound, can comprise nanoscale
particles. By "nanoscale" is meant that the magnetic particles have
an average particles size of less than 1 micron. Nanoscale magnetic
particles can have an average particle size of 10, 20, 30, 40, 50,
60, 70, 80 or 90 nm.+-.5 nm up to about 100, 200, 300, 400, 500,
600, 700, 800, 900 nm.+-.50 nm.
[0053] As an example, magnetized adsorbent particles can be formed
by impregnating PICA carbon with an aqueous solution of iron
nitrate at room temperature to form a mixture. Optionally, the
pressure over the mixture can be reduced (e.g., to about 2 mm Hg)
to improve infiltration of the iron nitrate solution in to the
pores of the carbon. The infiltrated carbon particles can be washed
to remove excess iron nitrate from the particles, and then dried
prior to heating to decompose the iron nitrate. Initially, magnetic
particles of iron oxide (Fe.sub.2O.sub.3) can be formed by heating
the iron nitrate-infiltrated carbon particles in air at a
temperature of about 350.degree. C. Further heating in a reducing
atmosphere (e.g., a gas mixture comprising carbon monoxide and
helium) at a temperature of between about 400-700.degree. C. can
reduce Fe.sub.2O.sub.3 to form magnetic particles comprising
Fe.sub.3O.sub.4 and/or Fe.
[0054] Magnetized adsorbent particles can be incorporated into the
filter element in a number of ways. Magnetized adsorbent particles
may be provided in the form of a dry powder, paste or dispersion in
a liquid. Magnetized adsorbent particles can be dusted on, sprayed
on, or combined with the filter material. For example, the
magnetized adsorbent particles can be mixed with a liquid (e.g.,
deionized water) to form a slurry. The slurry can then be dispersed
on the filter material used to form a filter rod. In a further
example, filter material (e.g., cellulose acetate material or paper
filler) may be rinsed or dip-coated with a slurry containing the
magnetized adsorbent particles.
[0055] The magnetized adsorbent particles may be added to cigarette
filter material supplied to a filter-making machine or incorporated
directly on a filter rod prior to wrapping a cigarette wrapper
around the rod to form a filter element. Preferably the magnetized
adsorbent particles are provided continuously along the length of a
filter element, though the magnetized adsorbent particles can be
provided at discrete locations along the length of a filter rod.
Thus, the magnetized adsorbent particles may be homogeneously or
non-homogeneously distributed along the length of a filter rod. For
example, a filter element can comprise a first loading of
magnetized adsorbent particles at one location along the filter rod
and a second loading of magnetized adsorbent particles at a second
location along the filter rod. A preferred filter rod comprising
magnetized adsorbent particles has a first loading of magnetized
adsorbent particles at the mouth end of the filter rod and a second
loading of magnetized adsorbent particles at the tobacco side of
the filter rod, wherein the first loading is less than the second
loading.
[0056] Magnetized adsorbent particles can be incorporated in paper
or other substrate material that is fitted into a passageway in a
filter element. The magnetized adsorbent particles may also be
incorporated in a liner or a plug in the interior of a filter
element. Alternatively, or in addition, the magnetized adsorbent
particles can be incorporated into the fibrous wall portions of a
filter element.
[0057] By way of example, the magnetized adsorbent particles can be
incorporated into or onto a support such as paper (e.g., liner,
plug wrap or tipping paper) that is located along a filter portion
of a cigarette. The magnetized adsorbent particles can also be
loaded onto a support such as lightly or tightly folded paper
inserted into a hollow portion of the cigarette filter. The support
is preferably in the form of a sheet material such as crepe paper,
filter paper, or tipping paper. However, other suitable support
materials such as organic or inorganic cigarette compatible
materials can also be used.
[0058] The magnetized adsorbent particles may be incorporated in
cigarette paper (e.g., paper wrapper and/or paper filler) before or
after the cigarette paper is incorporated into a cigarette. The
magnetized adsorbent particles can be incorporated into the
cellulosic web of the paper by depositing the magnetized adsorbent
particles directly on the cellulosic web or on web-filler material
that is incorporated in the paper. Magnetized adsorbent particles
can be incorporated into cigarette paper and/or into the raw
materials used to make cigarette paper (e.g., incorporated into the
paper stock of a cigarette paper making machine).
[0059] The magnetized adsorbent particles can be incorporated in
cigarette paper and/or filter material by spraying or otherwise
coating the particles onto the base material. For example,
magnetized adsorbent particles can be incorporated in cigarette
paper by spray coating the magnetized adsorbent particles onto a
wet base (e.g., cellulosic) web, an intermediate web or a finished
web. In another method, slurry (e.g., aqueous slurry) of the
magnetized adsorbent particles can be incorporated into the head
box of a paper-making machine and the magnetized adsorbent
particles can be incorporated into cigarette paper during the
paper-making process. Magnetized adsorbent particles in the form of
a dry powder can be physically admixed with cigarette paper and/or
filter material during the manufacturing process.
[0060] Any conventional or modified cigarette filter may
incorporate the magnetized adsorbent particles. The magnetized
adsorbent particles can be incorporated in a hollow portion of a
cigarette filter. For example, some cigarette filters have a
plug/space/plug configuration in which the plugs comprise a fibrous
filter material (e.g., polypropylene or cellulose acetate fibers)
and the space is simply a void between the two filter plugs. That
void can be filled partially or wholly with the magnetized
adsorbent particles. The magnetized adsorbent particles can be used
in granular form or loaded onto a suitable support such as a fiber
or thread.
[0061] The quantity, location and distribution in a cigarette of
the magnetized adsorbent particles can be selected as a function of
the airflow characteristics exhibited during smoking in order to
adjust, e.g., increase or maximize, adsorption of at least one gas
phase constituent in the mainstream smoke of the cigarette during
smoking. A typical filter element will include from about 10 mg to
about 200 mg of the magnetized adsorbent particles, although the
amount needed can also be determined by routine experimentation
and/or adjusted accordingly. The magnetized adsorbent particles can
selectively adsorb/filter specific constituents from the mainstream
smoke of a cigarette. Furthermore, as disclosed below, the
distribution of magnetized adsorbent particles can be selected such
that the amount of carbon monoxide and/or the amount of nitric
oxide in mainstream smoke is reduced during smoking of a
cigarette.
[0062] In addition to incorporating the magnetized adsorbent
particles in the filter element or in cigarette paper, the
magnetized adsorbent particles may be incorporated in the cut
filler used to form a cigarette.
[0063] In all such filter element configurations, the resistance to
draw (RTD) of the filter element comprising magnetized adsorbent
particles and at least one magnetic substrate is preferably less
than about 5 inches of water when measured at an air flow velocity
of about 1050 cc/min.
[0064] The following examples are illustrative. In an embodiment,
magnetized adsorbent particles and magnetic beads can be
incorporated into the filter material of the filter element itself.
This embodiment is illustrated in FIG. 1, which shows a cigarette 2
comprised of a tobacco rod 4 and a filter element 6. The filter
element 6 can comprise a tube or plug of material such as cellulose
acetate fibers 8 having magnetized adsorbent particles 9 and
magnetic beads 10 dispersed therein. The magnetized adsorbent
particles and/or the magnetic beads can be supported by the
cellulose acetate fibers. The tobacco rod 4 and the filter element
6 can be joined together with tipping paper (not shown).
[0065] In a further embodiment, magnetic beads can be incorporated
into the filter element as a gas permeable bed. A magnetic
substrate may be incorporated into more than one component of a
filter element such as by being incorporated into a void space as a
bed of packed particles. FIG. 2 shows a cigarette 2 comprised of a
tobacco rod 4 and filter element 6. This arrangement is similar to
that of FIG. 1 except the magnetic beads 10 are incorporated in a
space 20 of the filter element. Preferably, space 20 is free of
cellulose acetate and is located at or near the distal end of the
cigarette. As in Example 1, the tobacco rod 4 and filter element 6
can be joined together with tipping paper (not shown).
[0066] A magnetic substrate can be formed around (e.g., crimped
around) an exterior surface of the filter rod prior to wrapping the
filter rod in the plug wrap. Referring to FIG. 3, cigarette 2
comprises tobacco rod 4 and filter element 6. The filter element
further comprises magnetized adsorbent particles 9, and at least
one magnetic ring 30 that is disposed radially around the filter
rod. The thickness of the magnetic ring is preferably about 1 mm,
and can be any suitable axial length that is less than the length
of the filter rod. The tobacco rod 4 and the filter element 6 can
be joined together with tipping paper (not shown). Further, the
filter element 6 may include a filter overwrap (not shown).
Preferably the magnetic ring is external to the filter rod and the
filter overwrap is wrapped around both the filter rod and the
magnetic ring. The magnetic ring 30 is preferably located at or
near the distal end of the cigarette.
[0067] Other exemplary embodiments of a cigarette are shown in
FIGS. 4-5, wherein cigarette 2 comprises tobacco rod 4 and filter
element 6. In FIG. 4 the filter element further comprises
magnetized adsorbent particles 9, and magnetic rods 40 that are
arranged axially along the length of the filter element. In FIG. 5
the filter element further comprises magnetized adsorbent particles
9, and magnetic rods 50 that are arranged axially along the length
of the filter element. In FIG. 4, the magnetic rods are external to
the filter rod 44 and a filter overwrap 46 is wrapped around both
the filter rod and the magnetic rods.
[0068] A magnetic substrate, such as one or more magnetic rods, can
be incorporated into the filter material such that the filter
material substantially surrounds the magnetic substrate. In FIG. 5,
the magnetic rods 50 are disposed axially within the filter rod
such that the filter material substantially surrounds the magnetic
rods.
[0069] A further exemplary embodiment of a cigarette comprising a
magnetic mesh is shown in FIG. 6. Cigarette 2 comprises tobacco rod
4, magnetized adsorbent particles 9 incorporated within the filter
rod, and a magnetic mesh 60 external to the filter rod. A filter
overwrap is preferably wrapped around both the filter rod and the
magnetic mesh.
[0070] The magnetized adsorbent particles and/or the magnetic
substrate can affect the organoleptic properties (e.g., aroma
and/or taste) of mainstream smoke. Both the magnetized adsorbent
particles and the magnetic substrate can change the chemical
composition of mainstream gas that flows through a filter element.
For example, the magnetized adsorbent particles can adsorb one or
more gas phase constituents. Thus, the magnetized adsorbent
particles can reduce the content in mainstream smoke of one or more
gaseous constituents such as 1,3-butadiene, acrolein, isoprene,
propionaldehyde, acrylonitrile, benzene, toluene, styrene,
acetaldehyde and hydrogen cyanide. Preferably, however, the
magnetized adsorbent particles do not substantially reduce the
concentration in mainstream smoke of flavor components of the
smoke.
[0071] As disclosed above, the magnetized adsorbent particles
comprise magnetic particles incorporated within the adsorbent
particles. The magnetic particles, which can be elemental metals
(e.g., iron) or compound oxides (e.g., iron oxides), can affect the
concentration of one or more gas phase constituents of mainstream
smoke. For example, the magnetic particles, which can comprise
nanoscale particles, can catalyze the conversion of one or more gas
phase constituents during the smoking of a cigarette. As used
herein, a catalyst can affect the rate of a chemical reaction
without participating as a reactant or product of the reaction.
[0072] The magnetic particles, which are preferably capable of
acting as both an oxidant and as a catalyst (e.g., low temperature
or near-ambient temperature catalyst) for the conversion of carbon
monoxide to carbon dioxide and/or nitric oxide to nitrogen, and can
reduce the amount of carbon monoxide and/or nitric oxide in the
mainstream smoke of a cigarette during smoking.
[0073] The amount of magnetized adsorbent particles can be selected
such that the amount of carbon monoxide and/or nitric oxide in
mainstream smoke is reduced during smoking of a cigarette.
Preferably, the amount of magnetized adsorbent particles will be a
catalytically effective amount; e.g., an amount sufficient to
catalyze and/or oxidize at least 10%, more preferably at least 25%,
of the carbon monoxide in mainstream smoke to carbon dioxide. A
catalytically effective amount of magnetized adsorbent particles
can catalyze and/or reduce at least 10%, more preferably at least
25%, of the nitric oxide in mainstream smoke to nitrogen.
[0074] A filter element can comprise a mixture of different
magnetized adsorbent particles. The composition of the magnetized
adsorbent particles (i.e., the stoichiometry and/or size of the
catalyst particles and/or the stoichiometry and/or size of the
adsorbent particles) can be selected to adsorb, catalyze and/or
reduce gas phase constituents of mainstream smoke in a given
temperature range.
[0075] Yet another embodiment provides a method of treating
mainstream smoke of a cigarette comprising a filter element.
"Smoking" of a cigarette means the heating or combustion of the
cigarette to form smoke, which can be drawn through the cigarette.
Generally, smoking of a cigarette involves lighting one end of the
cigarette and, while the tobacco contained therein undergoes a
combustion reaction, drawing smoke from the combustion through the
mouth end of the filter element. The cigarette may also be smoked
by other means. For example, the cigarette may be smoked by heating
the cigarette and/or heating using electrical heater means as
described in commonly-assigned U.S. Pat. Nos. 6,053,176; 5,934,289;
5,591,368 or 5,322,075.
[0076] A method of making a filter element comprising filter
material, magnetized adsorbent particles and at least one magnetic
substrate comprises (i) providing filter material and plug wrap
material; (ii) forming the filter material into a filter rod; (iii)
incorporating the magnetized adsorbent particles and the at least
one magnetic substrate in and/or on at least one of the filter rod
and the plug wrap material; and (iv) wrapping the filter rod in the
plug wrap material to form the filter element.
[0077] While preferred embodiments have been described, it is to be
understood that variations and modifications may be resorted to as
will be apparent to those skilled in the art. Such variations and
modifications are to be considered within the purview and scope of
the claims appended hereto.
[0078] All of the above-mentioned references are herein
incorporated by reference in their entirety to the same extent as
if each individual reference was specifically and individually
indicated to be incorporated herein by reference in its
entirety.
* * * * *