U.S. patent application number 14/813224 was filed with the patent office on 2019-02-28 for cigarette wrapper with printed catalyst.
This patent application is currently assigned to PHILIP MORRIS USA INC.. The applicant listed for this patent is PHILIP MORRIS USA INC.. Invention is credited to Hector ALONSO, Rajesh K. GARG, Shalva GEDEVANISHVILI, Ping LI, Firooz RASOULI, Weijun ZHANG.
Application Number | 20190059441 14/813224 |
Document ID | / |
Family ID | 33551783 |
Filed Date | 2019-02-28 |
United States Patent
Application |
20190059441 |
Kind Code |
A9 |
LI; Ping ; et al. |
February 28, 2019 |
CIGARETTE WRAPPER WITH PRINTED CATALYST
Abstract
A wrapper for a smoking article includes a web; and a patterned
deposit on at least a portion of one surface of the wrapper,
wherein the patterned deposit comprises catalyst particles. The
patterned deposit can include a nanoparticle catalyst that is
capable of catalyzing the conversion of a constituent gas component
in the mainstream and/or sidestream smoke of the smoking article.
The constituent gas component can be carbon monoxide and/or nitric
oxide and the catalyst particles can be iron oxide. Also provided
is a smoking article comprising a tobacco rod having a wrapper
formed around the tobacco rod, the wrapper including a patterned
deposit on at least a portion of one surface of the wrapper. A
method of making the wrapper and a method of making a smoking
article utilizing the wrapper are also provided.
Inventors: |
LI; Ping; (Richmond, VA)
; GEDEVANISHVILI; Shalva; (Richmond, VA) ;
RASOULI; Firooz; (Midlothian, VA) ; ZHANG;
Weijun; (Richmond, VA) ; GARG; Rajesh K.;
(Richmond, VA) ; ALONSO; Hector; (Richmond,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PHILIP MORRIS USA INC. |
Richmond |
VA |
US |
|
|
Assignee: |
PHILIP MORRIS USA INC.
Richmond
VA
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160198760 A1 |
July 14, 2016 |
|
|
Family ID: |
33551783 |
Appl. No.: |
14/813224 |
Filed: |
July 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10560396 |
Nov 2, 2006 |
9119421 |
|
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PCT/US04/18854 |
Jun 14, 2004 |
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14813224 |
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60477922 |
Jun 13, 2003 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A24B 15/287 20130101;
A24C 5/005 20130101; C09D 11/03 20130101; A24B 15/28 20130101; D21H
19/68 20130101; A24D 1/02 20130101; A24D 1/002 20130101; A24B
15/282 20130101; A24B 15/286 20130101; A24B 15/288 20130101; A24D
1/025 20130101; D21H 23/24 20130101 |
International
Class: |
A24D 1/02 20060101
A24D001/02; A24D 1/00 20060101 A24D001/00; A24C 5/00 20060101
A24C005/00; C09D 11/03 20060101 C09D011/03; D21H 19/68 20060101
D21H019/68; D21H 23/24 20060101 D21H023/24 |
Claims
1. A method of making a smoking article, comprising: (i) depositing
catalyst particles on at least a portion of a surface of a wrapper
to form a patterned deposit of the particles on the wrapper; (ii)
providing a cut filler comprising tobacco to a cigarette making
machine; and (iii) placing the wrapper including the patterned
deposit around the cut filler to form a tobacco rod portion of the
smoking article.
2. The method of claim 1, wherein the catalyst particles are
deposited by gravure printing, rotogravure printing, photogravure
printing, screen printing, flexographic printing, relief printing,
intaglio printing, lithographic printing, spraying, brushing,
rolling or size press techniques.
3. The method of claim 1, wherein the catalyst particles are
deposited by dispersing the particles in a liquid to form a mixture
and depositing the mixture on the wrapper.
4. The method of claim 3, further comprising drying the patterned
deposit by heating the wrapper.
5. The method of claim 1, wherein the wrapper is a first wrapper
and the method further comprises: (iv) placing a second wrapper
around the tobacco rod portion.
6. The method of claim 5, wherein: (a) the second wrapper is
radially outward from the first wrapper; (b) the total amount of
catalyst particles on the second wrapper is zero; and/or (c) a
ratio, in weight percent, of catalyst particles on the second
wrapper to catalyst particles on the first wrapper is less than
0.25.
7. The method of claim 1, wherein: (a) the catalyst particles
comprise particles of a first oxide supported on particles of a
second compound; or (b) the catalyst particles comprise particles
of a first oxide supported on particles of a second compound, the
second compound comprises calcium carbonate.
8. The method of claim 1, wherein: (a) the wrapper has a linearly
distal portion and a linearly proximal portion with respect to a
first end of the smoking article, and the linearly distal portion
has a first loading of the catalyst particles and the linearly
proximal portion has a second loading of the catalyst particles;
and/or (b) the first loading of the catalyst particles is less than
the second loading of the catalyst particles.
9. The method of claim 1, wherein: (a) the catalyst particles are
deposited by gravure printing, rotogravure printing, photogravure
printing, screen printing, flexographic printing, relief printing,
intaglio printing, lithographic printing, spraying, brushing,
rolling or size press techniques; (b) the catalyst particles are
deposited in the absence of a binder; (c) dry catalyst particles
are deposited on a base web of the wrapper; (d) the average
particle size of the catalyst particles is less than about 5
microns or less than about 50 nm; (e) the catalyst particles
comprise at least one oxide of at least one element selected from
the group consisting of B, Al, Si, Ti, Fe, Co, Ni, Cu, Zn, Ge, Zr,
Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt and Au;
(f) the catalyst particles comprise iron oxide; (g) the catalyst
particles comprise FeOOH, Fe.sub.3O.sub.4, .alpha.-Fe.sub.2O.sub.3,
.gamma.-Fe.sub.2O.sub.3, FeO or mixtures thereof; (h) the patterned
deposit includes a plurality of discrete features including an
alphanumeric sequence, a pictogram or a geometric shape; (i) the
patterned deposit includes a concentration gradient of the catalyst
particles between a first portion having a low concentration
feature and a second portion having a high concentration feature;
(j) the catalyst particles are deposited on an inner surface of the
wrapper; (k) the catalyst particles are deposited on an outer
surface of the wrapper; (l) the permeability of the wrapper is no
less than 15 CORESTA units; (m) the areal coverage of catalyst on
the wrapper is less than about 90% or less than about 50% of the
total surface area of the wrapper; (n) the areal coverage of
catalyst on the wrapper is greater than about 1% or greater than
about 5% of the total surface area of the wrapper; (o) the features
of the pattern repeat such that the largest area of uncoated
wrapper does not exceed a circular area having a diameter of 1
micron or a diameter of 10 mm; (p) the total amount of the catalyst
is less than about 10 mg/smoking article or less than about 100
mg/smoking article; (q) the particles are deposited in an amount
effective to reduce the concentration in mainstream and/or
sidestream smoke of carbon monoxide and/or nitric oxide by at least
10% or by at least 25%; and/or (r) the catalyst is hydrogen bonded
to the wrapper.
10. A wrapper for a smoking article, the wrapper comprising: a web;
and a patterned deposit on at least a portion of one surface of the
wrapper, wherein the patterned deposit comprises catalyst
particles.
11. A sheet of cigarette wrapping paper comprising a plurality of
the wrappers of claim 10.
12. The wrapper of claim 10, wherein: (a) the average particle size
of the catalyst is less than about 5 microns or less than about 50
nm; (b) the catalyst comprises iron oxide; (c) the catalyst
comprises particles of a first oxide supported on particles of a
second compound; (d) the deposit includes a pattern having a
plurality of discrete features including an alphanumeric sequence,
a pictogram or a geometric shape; (e) the pattern includes a
concentration gradient of the catalyst between a first portion
having a low concentration feature and a second portion having a
high concentration feature; (f) the permeability of the wrapper is
no less than 15 CORESTA units; (g) the areal coverage of catalyst
on the wrapper is less than about 90% or less than about 50% of the
total surface area of the wrapper; (h) the areal coverage of
catalyst on the wrapper is greater than about 1% or greater than
about 5% of the total surface area of the wrapper; and/or (i) the
features of the pattern repeat such that the largest area of
uncoated wrapper does not exceed a circular area having a diameter
of 1 micron or a diameter of 10 mm.
13. A method of manufacturing cigarette paper with a patterned
deposit of catalyst particles, the method comprising: (i) forming a
sheet of cigarette paper in a papermaking machine; and (ii)
depositing catalyst particles on at least a portion of a surface of
the paper to form a patterned deposit of the particles on the
paper.
14. The method of claim 13, wherein: (a) the catalyst particles are
deposited by gravure printing, rotogravure printing, photogravure
printing, screen printing, flexographic printing, relief printing,
intaglio printing, lithographic printing, spraying, brushing,
rolling or size press techniques; (b) the catalyst particles are
deposited in the absence of a binder; (c) the average particle size
of the catalyst particles is less than about 5 microns or less than
about 50 nm; (d) the catalyst particles comprise iron oxide; and/or
(e) the patterned deposit includes a plurality of discrete features
including an alphanumeric sequence, a pictogram or a geometric
shape.
15. A catalytic ink utilized in production of a wrapper for a
smoking article, the catalytic ink comprising: a liquid; and a
nanoparticle catalyst suspended in the liquid.
16. The catalytic ink of claim 15 wherein the ink consists
essentially of: a liquid; and a nanoparticle catalyst suspended in
the liquid.
17. The catalytic ink of claim 16, wherein the ink is binder-free.
Description
BACKGROUND
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/560,396, filed Nov. 2, 2006 which is a national stage
application under 35 USC .sctn.371 of International Application
Number PCT/US2004/018854, filed June 14, 2004, the International
Application being published in English, which also claims priority
under 35 USC .sctn. 119 to U.S. Provisional Application No.
60/477,922, filed on Jun. 13, 2003, the entire content of, each of
which is hereby incorporated by reference.
[0002] In the description that follows reference is made to certain
structures and methods, however, such references should not
necessarily be construed as an admission that these structures and
methods qualify as prior art under the applicable statutory
provisions. Applicants reserve the right to demonstrate that any of
the referenced subject matter does not constitute prior art.
[0003] Smoking articles, such as cigarettes or cigars, produce both
mainstream smoke during a puff and sidestream smoke during static
burning. Constituent of both mainstream smoke and sidestream smoke
are carbon monoxide (CO), nitric oxide (NO) and particulate matter
(e.g., tar). The reduction of carbon monoxide, nitric oxide and
particulate matter in cigarette smoke is desirable.
[0004] Catalysts, sorbents, and/or oxidants for smoking articles
are disclosed in the following: U.S. Pat. No. 6,371,127 issued to
Snider et al., U.S. Pat. No. 6,286,516 issued to Bowen et al., U.S.
Pat. No. 6,138,684 issued to Yamazaki et al., U.S. Pat. No.
5,671,758 issued to Rongved, U.S. Pat. No. 5,386,838 issued to
Quincy, III et al., U.S. Pat. No. 5,211,684 issued to Shannon et
al., U.S. Pat. No. 4,744,374 issued to Deffeves et al., U.S. Pat.
No. 4,453,553 issued to Cohn, U.S. Pat. No. 4,450,847 issued to
Owens, U.S. Pat. No. 4,182,348 issued to Seehofer et al., U.S. Pat.
No. 4,108,151 issued to Martin et al., U.S. Pat. No. 3,807,416, and
U.S. Pat. No. 3,720,214. Published applications WO 02/24005,WO
87/06104, WO 00/40104 and U.S. Patent Application Publication Nos.
2002/0002979 A1, 2003/0037792 A1 and 2002/0062834 A1 also refer to
catalysts, sorbents, and/or oxidants.
[0005] Iron and/or iron oxide has been described for use in tobacco
products (see e.g., U.S. Pat. Nos. 4,197,861; 4,489,739 and
5,728,462). Iron oxide has been described as a coloring agent
(e.g., U.S. Pat. Nos. 4,119,104; 4,195,645; 5,284,166) and as a
burn regulator (e.g., U.S. Pat. Nos. 3,931,824; 4,109,663 and
4,195,645) and has been used to improve taste, color and/or
appearance (e.g., U.S. Pat. Nos. 6,095,152; 5,598,868; 5,129,408;
5,105,836 and 5,101,839).
[0006] Despite the developments to date, there remains an interest
in improved and more efficient methods and compositions for
reducing the amount of gas constituents in the mainstream and/or
sidestream smoke of a smoking article.
SUMMARY
[0007] Provided is a smoking article comprising a tobacco rod
having a wrapper formed around the tobacco rod, the wrapper
including a patterned deposit on at least a portion of one surface
of the wrapper, wherein the patterned deposit comprises catalyst
particles capable of catalyzing, oxidizing and/or reducing a
constituent gas component in the mainstream and/or sidestream smoke
of the smoking article. In smoking articles comprising the wrapper,
the concentration in mainstream and/or sidestream smoke of carbon
monoxide, nitric oxide and/or total particulate matter can be
reduced.
[0008] In a preferred embodiment, a wrapper for a smoking article
comprises a web and a patterned deposit on at least a portion of
one surface of the wrapper, wherein the patterned deposit comprises
catalyst particles. A plurality of wrappers can comprise a sheet of
cigarette wrapping paper.
[0009] A method of manufacturing cigarette paper with a patterned
deposit of catalyst particles comprises (i) forming a sheet of
cigarette paper in a papermaking machine; and (ii) depositing
catalyst particles on at least a portion of a surface of a wrapper
to form a patterned deposit of the particles on the wrapper. In a
preferred embodiment the catalyst particles are deposited without
using a binder and are hydrogen bonded to the wrapper (e.g., bonded
to the web comprising the wrapper).
[0010] Preferably, the catalyst particles comprise nanoscale
particles, which can have an average particle size of less than
about 5 microns, preferably less than about 50 nm, most preferably
less than about 10 nm. The catalyst particles are preferably metal
oxides such as iron oxide (e.g., FeOOH, Fe.sub.3O.sub.4,
.alpha.-Fe.sub.2O.sub.3, .gamma.-Fe.sub.2O.sub.3, FeO or mixtures
thereof), although the catalyst particles can comprise at least one
oxide of at least one element selected from the group consisting of
B, Al, Si, Ti, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag,
Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt and Au. The catalyst particles
can comprise particles of a first oxide supported on particles of a
second compound (e.g., iron oxide particles supported on calcium
carbonate particles).
[0011] The deposit preferably includes a pattern having a plurality
of discrete features such as an alphanumeric sequence, a pictogram
or geometric shapes, which can repeat along the length of the
paper. A pattern can comprise a random or regular array of
features. A first portion of the pattern can have a first
concentration of catalyst particles and a second portion of the
pattern can have a second concentration of catalyst particles.
Furthermore, the catalyst-patterned paper can be provided with a
gradient in the amount of catalyst along the length of the paper
and/or perpendicular to the plane of the paper.
[0012] The catalyst particles can be deposited on an inner and/or
outer surface of the wrapper. Also, a smoking article can have a
second wrapper having deposited thereon a different catalyst and/or
a different amount of catalyst than on the first wrapper. The
permeability of a preferred wrapper is no less than 15 CORESTA
units and the preferred areal coverage of catalyst on the wrapper
is less than about 90% or less than about 50% of the total surface
area of the wrapper. The catalyst particles can cover greater than
about 1% or greater than about 5% of the total surface area of the
wrapper. In a preferred embodiment, the features of the catalyst
pattern on the wrapper repeat such that the largest area of
uncoated wrapper does not exceed a circular area having a diameter
of 10 mm, more preferably a diameter of 1 micron.
[0013] An exemplary smoking article comprises less than about 10 mg
of the catalyst per smoking article or less than about 100 mg of
the catalyst per smoking article. The catalyst can be incorporated
into a smoking article in an amount effective to reduce the
concentration in mainstream and/or sidestream smoke of carbon
monoxide, nitric oxide and/or other smoke constituents by at least
10% or by at least 25%.
[0014] A preferred method of making a smoking article comprises (i)
depositing catalyst particles on at least a portion of a surface of
a wrapper to form a patterned deposit of the particles on the
wrapper; (ii) providing a cut filler comprising tobacco to a
cigarette making machine; and (iii) placing the wrapper including
the patterned deposit around the cut filler to form a tobacco rod
portion of the smoking article.
[0015] The catalyst particles can be deposited by gravure printing,
rotogravure printing, photogravure printing, screen printing,
flexographic printing, relief printing, intaglio printing,
lithographic printing, spraying, brushing, rolling or size press
techniques. The catalyst particles can be deposited by dispersing
the particles in a liquid (e.g., alcohols, water and/or other
solvents) to form a mixture and depositing the mixture on the
wrapper, or by depositing dry particles on a base web of a
wrapper.
[0016] Optionally, the catalyst particles can be deposited on a
wrapper in the form of a catalytic ink which includes a pigment.
The catalytic ink preferably comprises a liquid and a nanoparticle
catalyst suspended in the liquid.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0017] FIG. 1(a) shows an exemplary smoking article with a
particulate catalyst supported on the web-filler material of the
wrapper. FIG. 1(b) shows a magnified view of the wrapper.
[0018] FIG. 2(a) shows an exemplary smoking article with a
particulate catalyst supported on the web-filler material of a
first wrapper with a second outermost wrapper. FIG. 2(b) shows a
magnified view of the first wrapper with a second outermost
wrapper.
[0019] FIG. 3(a), FIG. 3(b), FIG. 3(c), FIG. 3(d), and FIG. 3(e)
illustrate exemplary discrete features and/or patterns of catalyst
particles on a wrapper for a smoking article.
[0020] FIG. 4 illustrates an exemplary construction of a cigarette,
which can be used with an electrical smoking device.
[0021] FIG. 5 is a perspective view of a cigarette having catalyst
modified paper surrounding a fuel element.
[0022] FIG. 6 shows a cross-sectional view of the cigarette shown
in FIG. 5.
[0023] FIG. 7 illustrates a cigarette having a concentric
tobacco.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Smoking articles comprising a wrapper, wrappers adapted for
use in smoking articles and methods for making smoking articles and
wrappers involve a patterned deposit of catalyst particles on at
least one surface of the wrapper. The catalyst particles are
capable of converting one or more gas constituents in the
mainstream and/or sidestream smoke of the smoking article. For
example, by providing a wrapper with the patterned deposit of
catalyst particles, the amount of carbon monoxide, nitric oxide
and/or total particulate matter in mainstream and/or sidestream
smoke can be reduced. By "deposit" is meant that the catalyst
particles are dispersed on a surface of the wrapper.
[0025] Preferably, the catalyst particles comprise nanoparticles.
By "nanoparticles" is meant that the particles have an average
particle diameter of less than about 500 nanometers, preferably
less than about 50 nm, more preferably less than about 10 nm. The
catalyst particles comprise at least one oxide of at least one
element selected from the group consisting of B, Al, Si, Ti, Fe,
Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W,
Re, Os, Ir, Pt and Au. Preferred catalyst particles are iron oxide
particles (e.g., nanoscale iron oxide particles.). A preferred
nanoparticle iron oxide catalyst is NANOCAT7 Superfine Iron Oxide,
available from Mach I, Inc., of King of Prussia, Pa. The
nanoparticle iron oxide catalyst can comprise FeOOH,
Fe.sub.3O.sub.4, .alpha.-Fe.sub.2O.sub.3, .gamma.-Fe.sub.2O.sub.3,
FeO or mixtures thereof.
[0026] An embodiment relates to a method of making cigarette paper
with a patterned deposit of catalyst particles, the method
comprising forming a sheet of cigarette paper in a papermaking
machine and depositing catalyst particles on at least a portion of
a surface of the paper to form a patterned deposit of the particles
on the paper. Such a paper wrapper is used to assemble a smoking
article, such as a cigarette, and is consumed during smoking.
Patterned deposits of catalyst particles can be deposited as dry
particles onto a base web of a wrapper. In a further embodiment,
the catalyst particles can be combined with a liquid to form a
slurry and the slurry can be deposited on at least a portion of one
surface of the wrapper. Preferably, the slurry consists of the
liquid and the catalyst particles (i.e., the slurry is free of a
binder).
[0027] A further embodiment relates to method of making a smoking
article, comprising (i) depositing catalyst particles on at least a
portion of a surface of a wrapper to form a patterned deposit of
the particles on the wrapper; (ii) providing a cut filler
comprising tobacco to a cigarette making machine; and (iii) placing
the wrapper including the patterned deposit around the cut filler
to form a tobacco rod portion of the smoking article.
[0028] While not wishing to be bound by theory, it is believed that
during smoking, the patterned deposit of particles such as iron
oxide nanoscale particles can catalyze the conversion of carbon
monoxide to carbon dioxide via reaction with oxygen in the gas
stream of the smoking article according to the equation 2
CO+O.sub.2=2CO.sub.2. The particles can also convert (e.g., reduce)
nitric oxide to nitrogen according to the reaction
2NO+2CO.fwdarw.2CO.sub.2+N.sub.2.
[0029] It is also believed that subsequent to the catalytic
reaction(s), the particles may also act as an oxidant that can
convert CO to CO.sub.2 in the absence of oxygen in order to reduce
the level of CO in the mainstream and/or sidestream smoke. As used
herein, a catalyst is capable of affecting the rate of a chemical
reaction, e.g., a catalyst can increase the rate of oxidation of
carbon monoxide without participating as a reactant or product of
the reaction. An oxidant is capable of oxidizing a reactant, e.g.,
by donating oxygen to the reactant, such that the oxidant itself is
reduced. A reducing agent is capable of reducing a reactant, e.g.,
by receiving oxygen from the reactant, such that the reducing agent
itself is oxidized. The catalyst particles can also reduce the
total particulate matter (TPM) (e.g., tar) in the gas stream.
[0030] Preferably, the catalyst particles are deposited on the
wrapper of a smoking article in an amount effective to reduce the
concentration in mainstream and/or sidestream smoke of carbon
monoxide, nitric oxide and/or total particulate matter by at least
5% (e.g., by at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%,
55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%).
[0031] "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 cigarette. 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.
[0032] 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 "sidestream"
smoke refers to the mixture of gases issuing from the tobacco rod
through the cigarette paper wrapper and/or from the burning coal of
the tobacco rod at the lit end.
[0033] Several factors contribute to the formation of carbon
monoxide in a cigarette. In addition to the constituents in the
tobacco, the temperature and the oxygen concentration in a
cigarette during combustion can affect the formation and reaction
of carbon monoxide and carbon dioxide. The total amount of carbon
monoxide formed during smoking comes from a combination of three
main sources: thermal decomposition (about 30%), combustion (about
36%) and reduction of carbon dioxide with carbonized tobacco (at
least 23%). Formation of carbon monoxide from thermal
decomposition, which is largely controlled by chemical kinetics,
starts at a temperature of about 180.degree. C. and finishes at
about 1050.degree. C. Formation of carbon monoxide and carbon
dioxide during combustion is controlled largely by the diffusion of
oxygen to the surface (k.sub.a) and via a surface reaction
(k.sub.b). At 250.degree. C., k.sub.a and k.sub.b, are about the
same. At 400.degree. C., the reaction becomes diffusion controlled.
Finally, the reduction of carbon dioxide with carbonized tobacco or
charcoal occurs at temperatures around 390.degree. C. and
above.
[0034] During smoking there are three distinct regions in a
cigarette: the combustion zone, the pyrolysis/distillation zone,
and the condensation/filtration zone. While not wishing to be bound
by theory, it is believed that the patterned deposit of catalyst
particles can target the various reactions that occur in different
regions of the cigarette during smoking. The patterned deposit of
catalyst particles can convert CO to CO.sub.2 in the absence or
presence of an external source of oxygen.
[0035] First, the combustion zone is the burning zone of the
cigarette produced during smoking of the cigarette, usually at the
lighted end of the cigarette. The temperature in the combustion
zone ranges from about 600.degree. C. to about 950.degree. C., and
the heating rate can be as high as 500.degree. C./second. The
concentration of oxygen is low in the combustion zone because
oxygen is being consumed in the combustion of tobacco to produce
carbon monoxide, carbon dioxide, water vapor and various organic
compounds. The low oxygen concentration coupled with the high
temperature leads to the reduction of carbon dioxide to carbon
monoxide by the carbonized tobacco. In this region, the catalyst
particles can convert carbon monoxide to carbon dioxide via an
oxidation and/or catalysis mechanism. The combustion zone is highly
exothermic and the heat generated is carried to the
pyrolysis/distillation zone.
[0036] The pyrolysis zone is the region behind the combustion zone,
where the temperature ranges from about 200.degree. C. to about
600.degree. C. In the combustion zone the catalyst particles can
also directly oxidize the conversion of CO to CO.sub.2 and/or
reduce NO to N.sub.2. The major reaction is the pyrolysis (i.e.,
the thermal degradation) of the tobacco that produces carbon
monoxide, carbon dioxide, smoke components and charcoal using the
heat generated in the combustion zone. There is some oxygen present
in this region, and thus the catalyst particles may catalyze the
oxidation of carbon monoxide to carbon dioxide. The catalytic
reaction begins at about 50.degree. C. and reaches maximum activity
around 150 to 300.degree. C. and maintains its maximum activity at
temperatures above about 300.degree. C.
[0037] In the condensation/filtration zone the temperature ranges
from ambient to about 150.degree. C. The major process in this zone
is the condensation/filtration of the smoke components.
[0038] Some amount of carbon monoxide, carbon dioxide and nitric
oxide diffuse out of the cigarette and some oxygen diffuses into
the cigarette. The partial pressure of oxygen in the
condensation/filtration zone does not generally recover to the
atmospheric level. In the relatively low temperature
condensation/filtration zone, the catalyst particles may optionally
catalyze the conversion of carbon monoxide to carbon dioxide and/or
nitric oxide to nitrogen.
[0039] During the smoking of a cigarette, carbon monoxide and
nitric oxide in mainstream smoke flow toward the filter end of the
cigarette. As these gases travel within the cigarette, oxygen
diffuses into and carbon monoxide and nitric oxide diffuse out of
the cigarette through the wrapper. After a typical 2-second puff of
a cigarette, CO and NO are concentrated in the periphery of the
cigarette, i.e., near the cigarette wrapper, in front of the
combustion zone. Due to diffusion of O.sub.2 into the cigarette,
the oxygen concentration is also high in the peripheral region.
Airflow into the tobacco rod is largest near the combustion zone at
the periphery of the smoking article and is approximately
commensurate with the gradient of temperature, i.e., higher airflow
is associated with larger temperature gradients. In a typical
cigarette, the highest temperature gradient is from the combustion
zone (>850-900.degree. C.) axially toward the filter end of the
cigarette. Within a few millimeters behind the combustion zone the
temperature drops to near ambient. Further information on airflow
patterns, the formation of constituents in cigarettes during
smoking and smoke formation and delivery can be found in Richard R.
Baker, "Mechanism of Smoke Formation and Delivery", Recent Advances
in Tobacco Science, vol. 6, pp. 184-224, (1980) and Richard R.
Baker, "Variation of the Gas Formation Regions within a Cigarette
Combustion Coal during the Smoking Cycle", Beitrage zur
Tabakforschung International, vol. 11, no. 1, pp. 1-17, (1981), the
contents of both are incorporated herein by reference.
[0040] The conversion rate of CO to CO.sub.2 and/or NO to N.sub.2
by the patterned catalyst particles is enhanced by the rapid and
efficient transport of CO and/or NO to the region of the catalyst
and CO.sub.2 and/or N.sub.2 away from the region of the catalyst,
e.g., via gas flow within the smoking article. Together, the
operating temperature and the air flow within the smoking article
can affect the operation of the catalyst.
[0041] The quantity, location and distribution on a wrapper of the
patterned deposit can be selected as a function of the temperature
and airflow characteristics exhibited during smoking in order to
adjust, e.g., increase or maximize the conversion rate of CO to
CO.sub.2 and/or NO to N.sub.2. The catalyst particles can be
selected so as to catalyze and/or oxidize in a given temperature
range, and the pattern geometry/distribution of the deposit can be
selected in order to coincide with the appropriate temperature for
catalysis/oxidation.
[0042] In many instances, a complete coating of print material upon
regions of a wrapper tends to have a occlusive effect, which tends
to inhibit diffusion of CO through the wrapper upstream of the
coal. By pattern printing, regions of the cigarette wrapper are
left unprinted and available to facilitate diffusion of CO through
the wrapper, while at the same time the printed regions are present
to contribute their catalytic effect. As a result, both diffusion
and catalysis are engaged to reduce CO during smoking of the
cigarette.
[0043] In embodiments of smoking articles described herein, any
suitable tobacco mixture may be used for the cut filler. Examples
of suitable types of tobacco materials include flue cured, Burley,
Maryland 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.
[0044] The tobacco column preferably comprises cut filler of a
blend of tobaccos typical of the industry, including blends
comprising bright, Burley and Oriental tobaccos and other blend
components, including traditional cigarette flavors. In the
preferred embodiment, the shredded tobacco (cut filler) of the
tobacco column comprises a blend of bright, Burley, Maryland and
Oriental tobaccos with or without inclusion of reconstituted
tobaccos or any after cut flavorings. Optionally, an expanded
tobacco component might be included in the blend to adjust rod
density, and flavors may be added. Optionally, a single variety of
the aforementioned tobaccos may be used instead of a blend.
[0045] In cigarette manufacture, the tobacco is normally employed
in the form of cut filler, i.e., 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 3.0 inches. The cigarettes may further
comprise one or more flavorants or other additives (e.g., burn
additives, combustion modifying agents, coloring agents, binders,
etc.).
[0046] A wrapper can be any wrapping surrounding the cut filler,
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
production of a smoking article such as a cigarette, the wrapper is
wrapped around cut filler to form a tobacco rod portion of the
smoking article by a cigarette making machine, which has previously
been supplied or is continuously supplied with tobacco cut filler
and one or more ribbons of wrapper. When supplied to the cigarette
making machine, the wrapper can be supplied from a single bobbin in
a continuous sheet (a monowrap) or from multiple bobbins (a
multiwrap, such as a dual wrap from two bobbins). Further, the
wrapper can have more than one layer in cross-section, such as in a
bi-layer paper as disclosed in commonly-owned U.S. Pat. No.
5,143,098, the entire content of which is herein incorporated by
reference.
[0047] Cigarettes may range from about 50 mm to about 120 mm in
length. Generally, a regular cigarette is about 70 mm long, a "King
Size" is about 85 mm long, a "Super King Size" is about 100 mm
long, and a "Long" is usually about 120 mm in length. The
circumference is from about 15 mm to about 30 mm in circumference,
and 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.
[0048] Referring to FIG. 1(a), a preferred embodiment of a smoking
article 100 has a tobacco rod portion 102 and filtering tip 104.
Optionally, embodiments of the smoking article 100 can be practiced
without a filtering tip 104. Preferably, the tobacco rod portion
102 comprises a column of tobacco 106 that is enwrapped with a
cigarette (tobacco) wrapper 108. As shown in expanded view in FIG.
1(b), a random deposit of catalyst particles 110 is on at least a
portion of the surface of the wrapper 108. In practice, the
catalyst particles 110 may penetrate an outer portion of the web of
fibrous cellulosic material 112 that forms the base material of the
wrapper 108.
[0049] The size distribution and the density of the catalyst
particles on the surface of the wrapper can affect the permeability
of the wrapper 108 (measured typically in units of CORESTA, which
is defined as the amount of air, measured in cubic centimeters,
that passes through one square centimeter of material in one minute
at a pressure drop of 1.0 kilopascals).
[0050] The pattern of catalyst particles, which can comprise a
random or regular array of features, can include a concentration
gradient or distribution of the particles per unit area of the
wrapper. For example, a concentration gradient of the catalyst
within the pattern can vary between a first portion having a low
concentration feature and a second portion having a high
concentration feature. The total loading of the catalyst particles
in a first, low concentration portion can be lower than that in a
second, high concentration portion. The first, low concentration
portion preferably has a total loading of catalyst less than about
1 mg, more preferably zero mg. The second, high concentration
portion preferably has a total loading of catalyst less than about
100 mg, more preferably 1 to 50 mg. The first, low concentration
portion and the second, high concentration portion can be,
respectively, the linearly distal portion and the linearly proximal
portion of the wrapper, with respect to an end of the smoking
article, such as the end with a filtering tip, if present. In
further embodiments, the loading of catalyst particles can vary
continuously or discontinuously and/or linearly or non-linearly
from the linearly distal portion to the linearly proximal
portion.
[0051] The concentration gradient can be achieved by varying the
surface area of the pattern (e.g., increasing the size of geometric
features or the font size of alphanumeric features). Additionally,
the concentration gradient can be achieved by varying the
concentration of the catalyst in the slurry that is deposited
(e.g., using a first concentration source in a first printing step
and a second concentration source in a second printing step to form
the deposit). By varying the concentration of the slurry that is
deposited, it is possible to vary the thickness of the discrete
features in the pattern (e.g., slurry having a high concentration
of catalyst particles can be used to print a thicker feature than
slurry having a low concentration of catalyst particles). A thicker
feature has more particles per area of the patterned deposit.
Finally, different catalyst material can be deposited (e.g., a
first low activity catalyst material and a second high activity
catalyst material can be used to form patterned deposits of varying
catalytic activity). By way of example, patterned catalytic
particles can be deposited using a single roller employing
successive applications (e.g., using a different catalyst and/or
catalyst concentration in each step), or by using multiple rollers
wherein each roller deposited a particular catalyst and/or catalyst
concentration.
[0052] The pattern of catalyst particles can decrease the
permeability of the wrapper by reducing the surface area for the
passage of air where the catalyst particles are printed. The
wrapper onto which the pattern is deposited can be any suitable
conventional wrapper. For example, a preferred wrapper having a
patterned deposit thereon can have a basis weight of from about 18
g/m.sup.2 to about 60 g/m.sup.2 and a permeability of from about 15
CORESTA units to about 80 CORESTA units. More preferably, the
wrapper has a basis weight from about 30 g/m.sup.2 to about 45
g/m.sup.2 and the permeability is about 30 to 35 CORESTA units.
However, any suitable basis weight and permeability for the wrapper
can be selected. The concentration of the deposited catalyst and
the particle size can be adjusted to achieve desired results.
[0053] Preferably, the catalyst is deposited on the wrapper so that
a permeability of the wrapper comprising the patterned deposit is
no less than 15 CORESTA units, preferably from 30 to 40 CORESTA
units. Other permeabilities of the wrapper (as measured by CORESTA
units) can be selected based on the application and location of the
wrapper. For example, in multilayer wrappers the permeability of a
first layer can be less than 1,000 CORESTA units, although a
permeability that is higher can be used. Thickness of single-layer
wrapper can preferably be from 15 to 100 microns, more preferably
from 20 to 50 microns. Additional layers in a multilayer wrapper
can be from 0.1 to 10 times the permeability of the first layer and
can have a thickness of from 0.1 to 2 times the thickness of the
first layer. Both the permeability and the thickness of the first
layer and the second layer can be selected to achieve a desired
total air permeability and total thickness for the smoking
article.
[0054] Referring again to FIG. 1, if desired the wrapper 108 can
optionally include a pattern-free portion of a surface. It is to be
understood that the patterned deposits shown on an outer surface of
the wrapper 108 in FIGS. 1(a) and 1(b) can be on an inner surface
of the wrapper or both on the inner and the outer surface, if
desired.
[0055] FIGS. 2(a) and 2(b) show an embodiment of a smoking article
with a patterned deposit on a portion of the surface of a first
wrapper with a second outermost wrapper. In the FIG. 2(a)
embodiment, the smoking article 100 includes a cigarette tobacco
column 106 surrounded by a first inner wrapper 114. As shown in
expanded view in FIG. 2(b), a patterned deposit 116 is on the
surface of at least a portion of the first wrapper 114. If desired,
the first wrapper 114 can optionally include a deposit-free surface
or a deposit-free portion of the surface.
[0056] In FIGS. 2(a) and 2(b), the smoking article 100 has a second
wrapper 118 surrounding the first wrapper 114. The total amount of
catalyst in the second outer wrapper 118 is preferably less than 1
mg for a given single smoking article 100, e.g., a single
cigarette. In one preferred embodiment, the second wrapper 118 is
catalyst free so as to provide an appearance to the cigarette 100
that is not affected by any coloration from the catalyst. In
exemplary embodiments, a total amount of catalyst particles in the
first wrapper is 1 to 100 mg and in the second wrapper is less than
1 mg, preferably 0 mg and/or a ratio, in weight percent, of a
catalyst in the second wrapper 120 to the catalyst in the first
wrapper 112 is less than 0.25. By way of example, a preferred
amount of catalyst per cigarette is 1 to 100 mg, 1 to 50 mg or 50
to 100 mg, 2 to 25 mg or 25 to 50 mg, 1 to 15 mg or 15 to 40 mg, or
4 to 10 mg or 10 to 20 mg.
[0057] It is to be understood that the first wrapper and the second
wrapper can be interchanged, if desired. For example, the outer
second wrapper can comprise the patterned deposit and the inner
first wrapper can have the same or a different arrangement of
catalyst particles or can be catalyst-free. Further, if the deposit
is not intended to be viewed, e.g., is not a pattern conveying a
desired image and or message to a viewing consumer, it may be
preferable from an aesthetic point of view to place the deposit on
an inner surface of a first wrapper, since some catalysts can
discolor the wrapper. An optional, catalyst-free, outer second
wrapper can then be placed about the inner first wrapper.
[0058] FIGS. 3(a) to 3(e) illustrate examples of regular patterns
of catalyst particles on wrappers for smoking articles. The
patterns comprise a plurality of discrete features. In exemplary
embodiments, the discrete features include an alphanumeric
sequence, a pictogram, or a geometric shape. Other optional forms
of the pattern include a variety of discrete patterns, such as in
the shape of crosshatch, ramps and/or gradients, irregular shapes,
and the like. In FIGS. 3(a) and 3(b), the wrapper 302 of the
smoking article 300 has a pattern 304 of discrete features
including an alphanumeric sequence 306. The pattern 304 also
includes a repeating series of geometric shapes, shown as lines
308. The pattern is repetitive in a first direction, either
linearly or circumferentially along the length of the smoking
article. The alphanumeric sequence 306 of the pattern 304 can be
oriented as desired for a given aesthetic effect, e.g., can be
oriented linearly (FIG. 3(a)) or circumferentially (FIG. 3(b)). In
FIGS. 3(c) to 3(e), the wrapper 302 of the smoking article 300 has
a pattern 304 of discrete features including a geometric shape. In
the illustrated examples, the geometric shapes include a
circumferential line 310 (FIG. 3(c)), and a series of overlapping
helixes 312 of a first density (FIG. 3(d)) and a second, higher
density (FIG. 3(e)).
[0059] In one approach, the catalyst particles are deposited onto
the wrapper of a smoking article by printing techniques. For
example, a cigarette made by conventional cigarette manufacturing
techniques and having any conventional blend of tobacco and tobacco
flavoring additives can have a pattern printed on the wrapping
paper by procedures known in cigarette manufacturing. Such
procedures generally involve the use of a soft impression roller or
rollers of a desired configuration. A pick-up roller rotating in a
slurry to be applied to the cigarette wrapper, e.g., a slurry
containing catalyst particles dispersed in a liquid, serves to
transfer the liquid to the impression roller for the printing step.
A preferred slurry does not contain a binder. Similarly, patterns
can be printed by the conventional techniques of gravure printing
and flexographic printing and/or relief, intaglio, or other
printing processes. The patterns can be incorporated onto the
wrapping paper using size press techniques, painting techniques,
rotogravure techniques, photogravure techniques, or the like. Other
methods used to deposit catalyst particles on a surface of wrapping
paper include electrostatic deposition, application with an
adhesive, patterned application with a printing applicator,
application in an ink solution using a printing process, spraying,
brushing and the like. Further, the catalyst particles can be
applied to a wrapper in a single coating step or in multiple
coating steps utilizing printing techniques and controlling the
amount of slurry applied in any one deposition. According to an
embodiment, dry catalyst particles can be deposited on a wetted
wrapper surface.
[0060] Pattern printing can be conducted by any one or a
combination of the aforementioned printing techniques. Further,
these printing operations can produce a patterned deposit of
catalyst particles on wrappers of assembled cigarettes and/or on
any side of a wrapper at any point prior to assembly of the
cigarette.
[0061] In preferred embodiments, the catalyst particles are
dispersed and/or suspended in an appropriate liquid to form a
catalytic ink (e.g., slurry). Any rapid drying liquid can be used
to form the slurry, for example, water, ethanol or acetone. The
catalytic ink can also include other constituents, such as an
aqueous component, a non-aqueous component, and/or a surfactant.
Preferably the slurry is binder free. Further optional components
of a catalytic ink include a rheology agent, which provides for
proper transfer of the ink during the printing process. For
printing on paper substrates, such as the wrapper used in smoking
articles, the printing ink preferably is adapted to the paper
substrate and may also include one or more of a resin, a solvent, a
defoaming agent and a drier.
[0062] In optional embodiments, the catalytic ink includes a
coloring agent, such as an organic or inorganic pigment. In an
example of a coloring agent, the pigment is a silica-based pigment
that produces a catalytic ink that results in a white dried
catalytic deposit. In addition to or as an alternative to pigments,
nanoparticle catalysts that impart a color or tint to the dried
deposit can also be used. For example, titanium-based nanoparticle
catalysts can impart a white color or shade to dried deposits.
[0063] The papermaking process can be carried out using
conventional paper making equipment. Cigarette wrappers can
comprise cellulosic material, which forms a web, and a web-filler,
which can be used to control the permeability of the paper.
[0064] The support web can be a conventional web, such as a flax
support web, or can include a web with an incorporated catalytic
component, such as a nanoparticle catalyst. If the support web
includes a catalytic component, the incorporated catalytic
component can be supported on a web-filler material or can be
directly supported on the support web without a web-filler
material. The web-filler includes CaCO.sub.3 particles or any other
suitable web-filler material, such as an oxide, a carbonate, or a
hydroxide of a Group II, Group III or Group IV metal, CaCO.sub.3,
TiO.sub.2, silicates such as SiO.sub.2, Al.sub.2O.sub.3,
MgCO.sub.3, MgO and Mg(OH).sub.2.
[0065] The wrapper can comprise a laminated wrapper, a bi-layer
wrapper or a multilayer wrapper. Examples of bi-layer and
multilayer wrappers are disclosed in commonly-owned U.S. Pat. No.
5,143,098, the entire content of which is herein incorporated by
reference.
[0066] In an embodiment of a bi-layer or multilayer wrapper
including patterned deposits of catalyst particles, at least one
surface of a radially inner layer and/or a radially outer layer can
comprise the patterned deposit. Preferably, a radially innermost
layer of the multilayer paper comprises the catalyst particles.
[0067] The wrapper having a patterned deposit of catalyst particles
thereon can be used to manufacture conventional cigarettes or
non-conventional cigarettes such as cigarettes for electrical
smoking systems 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;
5,499,636 and 5,388,594 or non-traditional types of cigarettes
having a fuel rod such as are described in commonly-assigned U.S.
Pat. No. 5,345,951.
[0068] FIG. 4 illustrates one type of construction of a cigarette
300, which can be used with an electrical smoking device. As shown,
the cigarette 300 includes a tobacco rod 360 and a filter portion
362 joined by tipping paper 364. The filter portion 362 preferably
contains a tubular free-flow filter element 302 and a mouthpiece
filter plug 304. The free-flow filter element 302 and mouthpiece
filter plug 304 may be joined together as a combined plug 310 with
plug wrap 312. The tobacco rod 360 can have various forms
incorporating one or more of the following items: an overwrap 371,
another tubular free-flow filter element 374, a cylindrical tobacco
plug 380 preferably wrapped in a plug wrap 384, a tobacco web 366
comprising a base web 368, and a void space 391. The patterned
deposit of catalyst particles, such as nanoscale catalyst
particles, is preferably printed onto the overwrap 371, but in
addition to or in the alternative, could be printed and/or
deposited onto any one or more of the plug-wrap 384 or a component
or components of the tobacco web 366.
[0069] FIG. 5 illustrates a cigarette 410 construction having a
fuel element 411 as described in U.S. Pat. No. 5,345,951, the
disclosure of which is hereby incorporated by reference. The
cigarette 410 includes the fuel element 411 and an expansion tube
412 overwrapped by cigarette wrapping paper 414, and a filter
element 413 attached by tipping paper 405. With reference to FIG.
6, the fuel element 411 includes a heat source 420 and a flavor bed
421 which releases flavored vapors and gases when contacted by hot
gases flowing through one or more longitudinal passages in the heat
source. The vapors pass into the expansion chamber 412 and then to
mouthpiece element 413. The heat source may contain substantially
pure carbon and optionally catalysts or burn additives. One or more
layers of paper 418 surrounding the heat source 420 can have
patterned catalyst particles printed thereon, e.g., by printing a
pattern of catalytic ink, and can be used to reduce CO, NO and/or
TPM produced by the heat source 420. Alternatively, or in addition
thereto, paper having a patterned deposit can be provided
downstream of the heat source 420. For example, paper comprising a
patterned deposit on at least one surface thereof can be located
between the heat source and the flavor bed 421 or in the flavor bed
421. Flavor bed 421 can include any material that releases
desirable flavors, e.g., tobacco filler or a substrate on which
flavor forming compounds (e.g., menthol) have been
incorporated.
[0070] The fuel element 411 is housed in a composite sleeve having
a radiant energy reflector sleeve 422 (e.g., perforated metallized
paper) and optional inner sleeve 423 (e.g., perforated metallized
paper). The inner sleeve 422 can be folded in to form a lip 424 at
the upstream end thereof to hold the heat source suspended away
from the interior wall of the reflector sleeve 422 with an annular
space therebetween. Flavor bed 421 is held within inner sleeve 423.
The wrapper 414 which holds the fuel element and expansion chamber
412 together preferably has sufficient porosity to allow air to be
admitted through the paper 414 and support combustion of the heat
source. The fuel element 411 also includes a reflective end cap 415
with one or more openings 416 to allow air into the fuel element
411. Smoking articles can include dual paper wrappers, e.g., an
inner wrapper and an outer wrapper. If desired, the paper having a
patterned catalytic deposit thereon can be used at other locations
and/or for any of the paper layers of the cigarette shown in FIGS.
5 and 6. Further, while one embodiment of a fuel element cigarette
is shown in FIGS. 5 and 6, paper comprising patterned catalytic
particles can be used to surround the fuel element and/or in place
of paper layers in other fuel element cigarette arrangements.
[0071] FIG. 7 illustrates a cigarette 500 having a concentric
tobacco rod 510 that includes an inner tube or sheath of cigarette
wrapper 515 having a patterned deposit of catalytic particles on at
least a portion of one surface of the wrapper. As shown, the
cigarette 500 comprises a filter 505 and a tobacco rod 510, which
are attached to one another with tipping paper 511. The tobacco rod
510 is a "concentric core" or "coaxial" configuration that can be
produced on a Hauni Baby rod making machine available from Hauni
Machinenbau AG of Hamburg, Germany. An inner core region 512 is
defined by the inner wrapper 515, which is surrounded by tobacco
cut filler material 520. An outer cigarette wrapper 525 extends
along the outside of the tobacco rod 510. The filter 505 can
comprise one or more plugs of cellulose tow and optionally could
include an adsorbent such as carbon. In this embodiment, any
coloration caused by the deposit of catalyst particles on the paper
in the inner wrapper 515 is hidden from view.
[0072] The central core region 512 can be hollow and/or can be
partially or wholly filled with tobacco cut filler and is
preferably approximately 2-5 mm in diameter, more preferably 2-3 mm
in diameter. In one alternative, the inner wrapper 515 can be
constructed in a layered arrangement with at least one of the
layers formed of paper having a patterned deposit of catalyst
particles on a surface thereof. The catalyst particles can be
deposited on an inner surface of the inner wrapper, an outer
surface of the inner wrapper, an inner surface of the outer wrapper
and/or an outer surface of the outer wrapper.
[0073] Referring again to the embodiment of FIGS. 2(a) and 2(b),
the inner wrapper and the outer wrapper are individual wrappers
formed in separate papermaking processes and later wrapped around
tobacco cut filler to from a cigarette tobacco rod. The inner
wrapper, the outer wrapper or both wrappers can include dried
deposits containing a nanoparticle catalyst. In examples where both
wrappers include a patterned deposit of catalytic particles, the
specific catalyst particles and the catalyst loading on each
wrapper can be the same or different. In some embodiments, the
addition of catalyst particles can discolor the wrapper, e.g., the
wrapper becomes non-white or brown. For aesthetic reasons, an outer
wrapper that is a conventional color, e.g., white, can be placed
around the inner wrapper. Both the inner wrapper and the outer
wrapper can be selected to give a desired smoking article
performance with respect to smoking article properties, such as
puff count, tar, burn rate, and ash appearance. Accordingly and as
shown and described, for example, with reference to FIGS. 2(a) and
2(b), preferred embodiments of smoking articles and methods of
making smoking articles can include a tobacco rod portion of a
cigarette with a patterned deposit of catalyst particles on a first
wrapper, further comprising a second outermost wrapper, which does
not have any catalyst particles deposited thereon.
[0074] A preferred catalyst for use on a wrapper for a smoking
article is catalytically active at temperatures as low as ambient
temperature and more preferably does not deactivate even at
temperatures as high as 900 EC. The catalyst particles can be
printed along the entire axial length of the anticipated burn zone,
e.g., not only at the filter end of the smoking article, and can be
catalytically active from the lit end to the filter end during use.
The axial distribution of the catalyst provides sufficient contact
time between the mainstream smoke and the catalyst for CO to be
converted to CO.sub.2 and/or NO to be converted to N.sub.2.
[0075] In a further example, the catalyst particles can comprise
mixed catalyst, e.g., a catalyst that is a combination of
individual catalyst compositions that each operate at a different
temperature range or overlapping temperature ranges. Such a mixture
of different catalyst particles can be used to broaden the
temperature range at which conversion of CO to CO.sub.2 and/or
conversion of NO to N.sub.2 can occur and to increase the catalytic
efficiency of the catalyst as the smoking article burns. For
example, a mixed catalyst may convert CO to CO.sub.2 and/or NO to
N.sub.2 both at the combustion zone and behind the combustion
zone.
[0076] When used on paper, the patterned catalyst can be selective
to CO. Thus, CO can be reduced by a greater proportion than
particulate matter (TPM). Thus, the CO:TPM ratio is reduced. A
control cigarette was smoked on a commercial smoking machine and
the amount of particulate matter and carbon monoxide in the
mainstream smoke was measured. The control cigarette comprised a
conventional wrapper. The mainstream smoke constituents for a test
cigarette comprising a wrapper having 12.5% by weight nanoscale
iron oxide particles printed on the inside of the wrapper were also
measured. The total particulate matter (TPM) and amount of carbon
monoxide (CO) issuing from the control cigarette were 18.3 mg and
14.7 mg, respectively. The TPM and CO amounts for the test
cigarette were 12.9 mg and 7.6 mg, respectively, corresponding to a
reduction in TPM and CO of 30% and 48%.
[0077] Any of the deposit material, wrappers, smoking articles or
methods described herein can include additional additives
conventionally used in wrappers for smoking articles. These
additives can include, for example, additives to control the
appearance, e.g., color, of the wrapper, additives to control the
burn rate of the wrapper, and/or additives to result in a desired
ash appearance and/or web-fillers used in cigarette paper.
[0078] Although the present invention has been described in
connection with exemplary embodiments thereof, it will be
appreciated by those skilled in the art that additions, deletions,
modifications, and substitutions not specifically described may be
made without departing from the spirit and scope of the invention
as defined in the appended claims.
* * * * *