U.S. patent application number 11/869475 was filed with the patent office on 2008-02-07 for low sidestream smoke cigarette with combustible paper having a modified ash.
Invention is credited to E. Robert Becker, Steve G. Chapman, Stanislav M. Snaidr.
Application Number | 20080029113 11/869475 |
Document ID | / |
Family ID | 28041877 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080029113 |
Kind Code |
A1 |
Snaidr; Stanislav M. ; et
al. |
February 7, 2008 |
LOW SIDESTREAM SMOKE CIGARETTE WITH COMBUSTIBLE PAPER HAVING A
MODIFIED ASH
Abstract
A low sidestream smoke cigarette comprises a conventional
tobacco rod, and a combustible treatment paper having a sidestream
smoke treatment composition. The treatment composition comprises in
combination, an oxygen storage and donor metal oxide oxidation
catalyst and an essentially non-combustible particulate adjunct for
said catalyst. Improvements are made in the treatment composition
and/or the addition of metal oxides or carbonates thereto to
improve ash characteristics.
Inventors: |
Snaidr; Stanislav M.;
(Mississauga, CA) ; Becker; E. Robert; (Wayne,
PA) ; Chapman; Steve G.; (Toronto, CA) |
Correspondence
Address: |
BANNER & WITCOFF, LTD.
1100 13th STREET, N.W.
SUITE 1200
WASHINGTON
DC
20005-4051
US
|
Family ID: |
28041877 |
Appl. No.: |
11/869475 |
Filed: |
October 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10388218 |
Mar 14, 2003 |
|
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11869475 |
Oct 9, 2007 |
|
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60364137 |
Mar 15, 2002 |
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Current U.S.
Class: |
131/334 |
Current CPC
Class: |
A24D 1/02 20130101 |
Class at
Publication: |
131/334 |
International
Class: |
A24B 15/18 20060101
A24B015/18 |
Claims
1. In a low sidestream smoke cigarette having a conventional
tobacco rod and a combustible treatment paper, said treatment paper
having a sidestream smoke treatment composition comprising an
oxygen storage and donor metal oxide oxidation catalyst and an
essentially non-combustible finely divided particulate adjunct for
said catalyst, the improvement comprising the use of a solid
solution of particulate mixed metal oxides as said catalyst and
said adjunct.
2. In a low sidestream smoke cigarette of claim 1, said oxygen
storage and donor metal oxide oxidation catalyst for the solid
solution being selected from the group consisting of lanthinum
oxide, cerium oxide, praseodymium oxide, neodymium oxide and
mixtures thereof.
3. In a low sidestream smoke cigarette of claim 1, said adjunct is
selected from the group of metal oxides consisting of zirconium
oxide, aluminum oxide, magnesium oxides, titanium oxide and
mixtures thereof.
4. In a low sidestream smoke cigarette of claim 1, said solid
solution of mixed metal oxides further comprising an oxidation
catalyst selected from the group consisting of palladium, platinum,
rhodium, tin oxide, copper oxide, iron oxide, manganese oxide and
mixtures thereof.
5. In a low sidestream smoke cigarette of claim 1, said solid
solution of mixed metal oxides being selected from the group
consisting of cerium/lanthinum mixed oxide, cerium/zirconium mixed
oxide, cerium/zirconium/lanthinum mixed oxide,
cerium/zirconium/praseodynium mixed oxide,
cerium/zirconium/lanthinum/praseodynium mixed oxide,
cerium/zirconium/neodymium mixed oxide and mixtures thereof.
6. In a low sidestream smoke cigarette of claim 1, said solid
solution being a high surface area porous particulate.
7. In a low sidestream smoke cigarette of claim 6, said solid
solution being a low surface area particulate.
8. In a low sidestream smoke cigarette of claim 6, wherein said
catalyst and said adjunct is said high surface area
cerium/zirconium mixed oxide.
9. In a low sidestream smoke cigarette of claim 1, wherein a
catalyst selected from the group consisting of palladium, platinum,
rhodium, tin oxide, copper oxide, iron oxide, manganese oxide and
mixtures thereof is either included in said solid solution of
cerium/zirconium mixed oxide or is applied to the surface of said
high surface area cerium/zirconium mixed oxide.
10. In a low sidestream smoke cigarette of claim 9, wherein said
cerium/zirconium mixed oxide has a particle size greater than about
1 .mu.m.
11. In a low sidestream smoke cigarette of claim 10, wherein said
cerium/zirconium mixed oxide has a particle size less than about 30
.mu.m.
12. In a low sidestream smoke cigarette of claim 8, wherein said
cerium/zirconium mixed oxide have a ratio ranging from about 5:95
to about 95:5.
13. In a low sidestream smoke cigarette of claim 12, wherein said
ratio is about 75:25 and said particle size is about 6 .mu.m to 10
.mu.m.
14. In a low sidestream smoke cigarette of claim 1, wherein said
treatment composition is incorporated within said treatment paper
at a loading rate of about 2.5 g/m.sup.2 to about 125
g/M.sup.2.
15. In a low sidestream smoke cigarette of claim 1, wherein said
treatment composition is coated on said treatment paper.
16. In a low sidestream smoke cigarette of claim 8, wherein said
treatment composition includes particulate zirconium oxide,
titanium oxide, magnesium oxide, aluminum oxide, cerium oxide, tin
oxide, iron oxide, manganese oxide, calcium carbonate, zirconium
carbonate, magnesium carbonate and mixtures thereof.
17. In a low sidestream smoke cigarette of claim 8, wherein said
treatment composition includes particulate zeolite.
18. In a low sidestream smoke cigarette of claim 17, wherein said
zeolite is a carrier for an oxidation catalyst selected from the
group consisting of palladium, platinum, rhodium, tin oxide, copper
oxide, iron oxide, manganese oxide, and mixtures thereof.
19. In a low sidestream smoke cigarette of claim 8, wherein said
treatment composition includes zirconium oxide.
20. A low sidestream smoke cigarette comprising a conventional
tobacco rod and a combustible treatment paper having a sidestream
smoke treatment composition, said treatment composition comprising
an oxygen storage and donor metal oxide oxidation catalyst, an
essentially non-combustible particulate adjunct for said catalyst
and a metal oxide or carbonate for modifying ash
characteristics.
21. A low sidestream smoke cigarette of claim 20, wherein said
adjunct is a high surface area particulate.
22. A low sidestream smoke cigarette of claim 21, wherein said
particulate adjunct is a zeolite based material ranging from about
0.1% by weight of total dry weight composition to about 60% by
weight of total dry weight composition and preferably less than 25%
by weight and most preferably less than 15% by weight.
23. A low sidestream smoke cigarette of claim 21, wherein said ash
modifying metal oxide or carbonate is selected from the group
consisting of zirconium oxide, titanium oxide, magnesium oxide,
aluminum oxide, cerium oxide, tin oxide, iron oxide, manganese
oxide, calcium carbonate, zirconium carbonate, magnesium carbonate
and mixtures thereof.
24. A low sidestream smoke cigarette of claim 20, wherein said
adjunct is a support for a ceria sol to be applied thereto and
dried.
25. A low sidestream smoke cigarette of claim 24, wherein said
adjunct is high surface area cerium oxide.
26. A low sidestream smoke cigarette of claim 20, wherein said
oxygen storage and donor metal oxide oxidation catalyst is selected
from a group consisting of transition metal oxides, rare earth
metal oxides and mixtures thereof.
27. A low sidestream smoke cigarette of claim 26, wherein said
transition metal oxides are selected from the group consisting of
oxides of group IVB, VB, VIB, VIIB, VIIIB, IB metals and mixtures
thereof.
28. A low sidestream smoke cigarette of claim 27, wherein said rare
earth metal oxide is selected from the group consisting of oxides
consisting of scandium, yttrium and lanthanide metals and mixtures
thereof.
29. A low sidestream smoke cigarette of claim 20 wherein said
lanthanide metals oxide are selected from the group consisting of
lanthinum oxide, cerium oxide, praseodymium oxide, neodymium oxide
and mixtures thereof.
30. A low sidestream smoke cigarette of claim 29, wherein said
oxygen storage and donor metal oxide oxidation catalyst and adjunct
therefor is a solid solution of mixed metal oxides where the
adjuncts are selected from the group consisting of zirconium oxide,
aluminium oxide, magnesium oxide, titanium oxide and mixtures
thereof.
31. A low sidestream smoke cigarette of the preceding claim 30,
wherein said solid solution of mixed metal oxides comprises a
catalyst selected from the group consisting of palladium, platinum,
rhodium, tin oxide, copper oxide, iron oxide, manganese oxide.
32. A low sidestream smoke cigarette of claim 20, wherein said
solid solution of mixed metal oxides includes cerium/lanthinum
mixed oxides, cerium/zirconium mixed oxides, cerium/aluminum mixed
oxides, cerium/magnesium mixed oxides, cerium/titanium mixed
oxides, cerium/zirconium/lanthinum mixed oxides, cerium/lanthinum
mixed oxide, cerium/zirconium mixed oxide,
cerium/zirconium/lanthinum mixed oxide,
cerium/zirconium/praseodynium mixed oxide,
cerium/zirconium/lanthinum/pra-seodynium mixed oxide,
cerium/zirconium/neodymium mixed oxide.
33. A low sidestream smoke cigarette of claim 20, wherein said
adjunct is selected from the group consisting of clays essentially
non-combustible mill fibers, monolithe mineral base materials,
essentially non-combustible carbon, zeolytes and mixtures
thereof.
34. A low sidestream smoke cigarette of claim 33, wherein said
adjuncts are selected from the group consisting of zirconium oxide,
titanium oxide, magnesium oxide, aluminum oxide, cerium oxide, tin
oxide, iron oxide, manganese oxide, calcium carbonate, zirconium
carbonate, magnesium carbonate and mixtures thereof, metal oxide
fibers and milled porous ceramic fibers and mixtures thereof.
35. In a low sidestream smoke cigarette of claim 29, said solid
solution being a high surface area porous particulate.
36. In a low sidestream smoke cigarette of claim 29, said solid
solution being a low surface area particulate.
37. A low sidestream of smoke cigarette of claim 23, wherein said
ash modifying particulate is zirconium oxide.
38. A low sidestream smoke cigarette of claim 29, wherein an
oxidation catalyst is used with said oxygen storage and donor metal
oxide oxidation catalyst, said oxidation catalyst being selected
from the group consisting of palladium, platinum, rhodium, tin
oxide, copper oxide, iron oxide, manganese oxide, and mixtures
thereof.
39. A low sidestream smoke cigarette of claim 22, wherein said
zeolite is a Y-type zeolite, ZSM-5 type zeolite or Beta type
zeolite.
40. A low sidestream smoke cigarette of clam 29, wherein said
oxygen storage and donor metal oxide oxidation catalyst is a porous
particulate solid solution of cerium/zirconium which is preferably
a mixed oxide high surface area material.
41. A low sidestream smoke cigarette of claim 40, wherein zirconium
oxide and/or a zeolite are used in combination with said
cerium/zirconium mixed oxide.
42. A low sidestream smoke cigarette of claim 41, wherein an
oxidation catalyst is used with said cerium/zirconium metal oxide,
zirconium oxide and/or zeolite.
43. A low sidestream smoke cigarette of claim 42, wherein said
oxidation catalyst is selected from the group consisting of
palladium, platinum, rhodium, tin oxide, copper oxide, iron oxide,
manganese oxide, and mixtures thereof, said selected oxidation
catalyst being either incorporated in said solid solution of
cerium/zirconium mixed oxide or applied to surfaces of particulate
cerium/zirconium mixed oxide, zirconium oxide and/or zeolite.
44. A low sidestream smoke cigarette of claim 42, wherein said
zeolite is a Y-type zeolite.
45. A low sidestream smoke cigarette of claim 20, wherein said
treatment composition is applied as a coating to cigarette paper,
said coating composition including a metal oxide or carbonate
selected from the group consisting of zirconium oxide, titanium
oxide, magnesium oxide, aluminum oxide, cerium oxide, tin oxide,
iron oxide, manganese oxide, calcium carbonate, zirconium
carbonate, magnesium carbonate and mixtures thereof.
46. A low sidestream smoke cigarette of claim 20, wherein said
combustible treatment paper comprises an inner sheet and an outer
sheet, said inner sheet comprises said treatment composition for
reducing sidestream smoke, said outer layer comprising a treatment
composition for modifying ash characteristics.
47. A low sidestream smoke cigarette of claim 46, wherein said
inner paper has greater than 35% by weight of a zeolite
material.
48. A low sidestream smoke cigarette of claim 48, wherein said
inner paper and outer paper have said treatment composition coated,
incorporated or impregnated thereon or therein.
49. A low sidestream smoke cigarette of claim 48, wherein said
inner paper has said sidestream smoke reduction composition
incorporated therein.
50. A low sidestream smoke cigarette of claim 48, wherein said
inner paper has said sidestream smoke reduction composition coated
thereon.
51. A low sidestream smoke cigarette of claim 48, wherein said
inner paper has said sidestream smoke reduction composition
incorporated and coated thereon.
52. A low sidestream smoke cigarette of claim 48, wherein said
outer paper has said sidestream smoke reduction composition
incorporated thereon.
53. A low sidestream smoke cigarette of claim 48, wherein said
outer paper has said sidestream smoke reduction composition coated
thereon.
54. A low sidestream smoke cigarette of claim 48, wherein said
outer paper has said sidestream smoke reduction composition
incorporated and coated thereon.
55. A low sidestream smoke cigarette of claim 46 said inner paper
comprising an oxygen storage and donor metal oxide oxidation
catalyst with adjunct and a high surface area adsorptive material,
the outer layer comprising an oxygen storage and donor metal oxide
oxidation catalyst with adjunct and metal oxide for modifying ash
characteristics.
56. A low sidestream smoke cigarette of claim 55, wherein said
treatment composition for reducing sidestream smoke and said
treatment composition for modifying ash are applied as a coatings
respectively to said inner sheet and said outer sheet.
57. A low sidestream smoke cigarette of claim 56, wherein said
oxygen storage and donor metal oxide oxidation catalyst is a porous
particulate high surface area solid solution cerium/zirconium mixed
oxide.
58. A low sidestream smoke cigarette of claim 57, wherein said
cerium oxide and said zirconium oxide in said solid solution are in
a ratio of about 5:95 to about 95:5.
59. A low sidestream smoke cigarette of claim 58, wherein said
coating is applied to said inner and outer sheets on either or both
sides of each of said sheets.
60. A low sidestream smoke cigarette comprising a conventional
tobacco rod and a combustible treatment paper having a sidestream
smoke treatment composition, said treatment composition comprising
an oxygen storage and donor metal oxide oxidation catalyst, an
essentially non-combustible high surface area adjunct for said
catalyst incorporated in said treatment paper and a coating of
calcium carbonate on an exterior surface of said treatment paper to
modify ash characteristics.
61. A low sidestream smoke cigarette of claim 60, wherein said
adjunct includes a zeolite based material.
62. A low sidestream smoke cigarette of claim 61, wherein said
zeolite based material is in an amount ranging from about 0.1% by
weight of total dry weight composition to about 60% by weight of
total dry weight composition and preferably less than 25% and most
preferably less than 15%.
63. A low sidestream smoke cigarette of claim 60, wherein said
oxygen storage and donor metal oxide oxidation catalyst is selected
from a group consisting of transition metal oxides, rare earth
metal oxides and mixtures thereof.
64. A low sidestream smoke cigarette of claim 61, wherein said
transition metal oxides are selected from the group consisting of
oxides of group IVB, VB, VIB, VIIB, VIIIB, IB metals and mixtures
thereof.
65. A low sidestream smoke cigarette of claim 62, wherein said rare
earth metal oxide is selected from the group consisting of oxides
consisting of scandium, yttrium, lanthanide metals and mixtures
thereof.
66. A low sidestream smoke cigarette of claim 60, wherein said
lanthanide metal oxide is selected from the group consisting of
lanthinum oxide, cerium oxide, praseodymium oxide, neodymium oxide
and mixtures thereof.
67. A low sidestream smoke cigarette of claim 66, wherein said
oxygen storage and donor metal oxide oxidation catalyst and adjunct
therefor is a solid solution of mixed metal oxides where the
adjuncts are selected from the group consisting of zirconium oxide,
aluminium oxide, magnesium oxide, titanium oxide and mixtures
thereof.
68. A low sidestream smoke cigarette of the preceding claim 67,
wherein said solid solution comprises a metal catalyst selected
from the group consisting of palladium, platinum, rhodium, tin
oxide, copper oxide, iron oxide, manganese oxide and mixtures
thereof.
69. A low sidestream smoke cigarette of claim 68, wherein said
solid solution of mixed metal oxides includes cerium/lanthinum
mixed oxides, cerium/zirconium mixed oxides, cerium/aluminum mixed
oxides, cerium/magnesium mixed oxides, cerium/titanium mixed
oxides, cerium/zirconium/lanthinum mixed oxides, cerium/lanthinum
mixed oxide, cerium/zirconium mixed oxide,
cerium/zirconium/lanthinum mixed oxide,
cerium/zirconium/praseodynium mixed oxide,
cerium/zirconium/lanthinum/pra-seodynium mixed oxide,
cerium/zirconium/neodymium mixed oxide.
70. In a low sidestream smoke cigarette of claim 66, said solid
solution being a high surface area porous particulate.
71. A low sidestream smoke cigarette of claim 66, wherein an
oxidation catalyst is used with said oxygen storage and donor metal
oxide oxidation catalyst, said oxidation catalyst being selected
from the group consisting of palladium, platinum, rhodium, tin
oxides, copper oxides, iron oxides, manganese oxides, and mixtures
thereof.
72. A low sidestream smoke cigarette of claim 61, wherein said
zeolite is a Y-type zeolite, ZSM-5 type zeolite or Beta type
zeolite.
73. A low sidestream smoke cigarette of clam 72, wherein said
oxygen storage and donor metal oxide oxidation catalyst is a porous
particulate cerium/zirconium mixed oxide high surface area
material.
74. A low sidestream smoke cigarette of claim 73, wherein an
oxidation catalyst is used with said cerium/zirconium mixed oxide,
zirconium oxide and/or zeolite.
75. A low sidestream smoke cigarette of claim 74, wherein said
oxidation catalyst is selected from the group consisting of
palladium, platinum, rhodium, tin oxide, copper oxide, iron oxide,
manganese oxide, and mixtures thereof, said selected oxidation
catalyst being either incorporated in said solid solution of
cerium/zirconium mixed oxide or applied to surfaces of particulate
cerium/zirconium mixed oxide, zirconium oxide and/or zeolite.
76. A low sidestream smoke cigarette of claim 75, wherein said
zeolite is a Y-type zeolite.
77. A low sidestream smoke cigarette of claim 60, wherein a binder
for said calcium carbonate coating is selected from the group
consisting of polyvinylalcohol, starches, CMC, casein, soya,
binding clays, inorganic binders and mixtures thereof.
Description
FIELD OF THE INVENTION
[0001] The invention relates to sidestream smoke reduction in
burning cigarettes and other smoking products. More particularly,
the invention relates to cigarette paper, cigarette wrapper, or a
wrapper for a cigar or other like tobacco products for reducing
visible sidestream smoke while providing a modified ash.
BACKGROUND OF THE INVENTION
[0002] Various attempts have been made to reduce or eliminate
sidestream smoke emanating from a burning cigarette. The applicant
developed various approaches to cigarette sidestream smoke control
systems as described in its Canadian patents 2,054,735 and
2,057,962; U.S. Pat. Nos. 5,462,073 and 5,709,228 and published PCT
applications WO 96/22031; WO 98/16125 and WO 99/53778.
[0003] Other sidestream smoke control systems have been developed
which use filter material or adsorptive material in the tobacco,
filter or paper wrapper. Examples of these systems are described in
U.S. Pat. Nos. 2,755,207, 4,108,151 and 4,225,636; EP patent
applications 0 740 907 and 0 251 254; and WO 97/27831 and WO
99/53778. U.S. Pat. No. 2,755,207 describes a low sidestream smoke
cigarette paper. The cigarette paper on burning yields a smoke
substantially free of obnoxious components. The cigarette paper is
cellulosic material in fibre form. It has intimately associated
therewith a finely divided mineral type siliceous catalyst
material. The cigarette paper which is essentially non-combustible
and refractory remains substantially unchanged during combustion of
the cigarette paper and functions like a catalyst in modifying the
combustion of the paper. Suitable siliceous catalysts include
acid-treated clays, heat-treated montmorillonite and natural and
synthetic silicates containing some hydrogen atoms which are
relatively mobile. Suitable mixed silica oxides include silica
oxides with alumina, zirconia, titania, chromium oxide and
magnesium oxide. Other silicas include the oxides of silicon and
aluminum in a weight ratio of 9:1 of silica to alumina.
[0004] U.S. Pat. No. 4,108,151 describes the use of a gamma alumina
filler for cigarette paper which selectively reduces the organic
vapor phase constituents in tobacco smoke. There is at least 50% by
weight of alumina filler in the cigarette paper for reducing the
organic vapor phase constituents in a tobacco smoke. As a result
there is a reduction in the visible sidestream smoke eminating from
a burning cigarette. The gamma alumina is most commonly known as
activated alumina which is finely pulverized to pass through a
300-mesh screen.
[0005] U.S. Pat. No. 4,225,636 describes the use of carbon in the
cigarette paper to reduce organic vapour phase components and total
particulate matter found in sidestream smoke. In addition, the
carbon results in a substantial reduction in visible sidestream
smoke emitting from a burning cigarette. Activated carbon is
preferred as the carbon source. The use of the activated carbon
results in a slight drop in visible sidestream smoke. Up to 50% of
the cigarette paper may be finely divided carbon. The carbon-coated
papers may be used as the inner wrap for the tobacco rod in
combination with a conventional cigarette.
[0006] European patent application 0 740 907 published Nov. 6, 1996
describes the use of zeolites in the tobacco of the cigarette to
alter the characteristics of the mainstream smoke and in particular
remove various components from the mainstream smoke such as some of
the tars. The zeolite as provided in the tobacco, also apparently
change the characteristics of the sidestream smoke. The zeolites
used were of a particle size between 0.5 mm to 1.2 mm.
[0007] European application 0 251 254 describes the use of a high
superficial surface area filler in cigarette paper. The fillers are
generally crystals and solids having surface areas of at least 20
m.sup.2/g. The fillers are preferably, peroxides, carbonates,
phosphates, sulphates, aluminates and silicates. It is taught that
porous fillers such as zeolites are not preferred in cigarette
paper and are taught as functioning similarly to conventional
chalk.
[0008] Published PCT patent application WO 97/27831 describes the
use of a dealuminated zeolite for absorbing nonpolar or weakly
polar molecules form a polar liquid or gas. Effective amounts of
the powered dealuminated zeolite may be incorporated in cigarette
paper to reduce the carbon monoxide in sidestream smoke. The step
of dealuminating aluminous zeolite renders the zeolite hydrophobic
so as to affect absorption and removal of the nonpolar and weakly
polar molecules which even happens in the present of water.
[0009] Published PCT patent application WO 99/53778 describes a
non-combustible sheet of treatment material for reducing sidestream
smoke emissions. The sheet is used as a wrap and is applied over
conventional cigarette paper of a conventional cigarette. The wrap
has a very high porosity to allow the cigarette to burn at or close
to conventional free-burn rates while at the same time reduce
visible sidestream smoke emissions. The non-combustible wrap
includes non-combustible ceramic fibres, non-combustible activated
carbon fibres as well as other standard materials used in making
the wrap. The wrap also includes zeolites or other similar sorptive
materials and an oxygen donor/oxygen storage metal oxide oxidation
catalyst. The non-combustible wrap provides an acceptable degree of
sidestream smoke control, however, due to the non-combustible
nature of the wrap, a charred tube remains.
[0010] U.S. Pat. Nos. 4,433,697 and 4,915,117 describe the
incorporation of ceramic fibres in a cigarette paper manufacture.
U.S. Pat. No. 4,433,697 describes at least 1% by weight of certain
ceramic fibres in the paper furnish in combination with magnesium
oxide and/or magnesium hydroxide fillers to reduce visible
sidestream smoke emanating from the burning cigarette. The furnish
of fibre pulp, ceramic fibres and fillers are used to make a paper
sheet on conventional paper making machines. The ceramic fibres may
be selected from the group of polycrystalline alumina,
aluminum-silicate and amorphous alumina. A filler of magnesium
hydroxide or magnesium oxide is used and is coated on or applied to
the fibres of the sheet.
[0011] Ito, U.S. Pat. No. 4,915,117 describes a non-combustible
sheet for holding tobacco. The thin sheet is formed from ceramic
materials which upon burning produces no smoke. The ceramic sheet
comprises a woven or non-woven fabric of ceramic fibre or a mixture
of paper and ceramics thermally decomposed at high temperature. The
ceramic fibre may be selected from inorganic fibres such as silica
fibre, silica-alumina fibre, alumina fibre, zirconia fibre, or
alumino borosilicate and glass fibre. The ceramic sheet is formed
by binding these materials by inorganic binders such as silica gel
or alumina gel. The fibres are preferably 1 to 10 micrometers in
diameter.
[0012] Published PCT patent application WO 01/41590 describes the
use of ceramic materials in cigarette wrappers to reduce sidestream
smoke. The ceramic filler which is incorporated in the cigarette
wrapper using a binder has particle size in range of 2-90 .mu.m.
The ceramic filler is of a predefined shape which is spherical or
substantially spherical, oval or substantially oval or another
irregular shape approximating thereto. The ceramic filler may be
alumina, silica, an alumino-silicate, silicon carbide, stabilised
or un-stabilised zirconium oxide, zircon, garnet, feldspar and the
like. The ceramic filler is provided in the cigarette wrapper at
greater than 40% by weight of the dry materials in the slurry that
is used to produce the wrapper. The binder may be an alginate, a
gum, cellulose, pectin, starch or Group I or II metal salts of
these binders. The resultant wrapper has a porosity usually less
than 200 Coresta Units and is preferably in the range of 2-100
Coresta Units. The wrapper has a density of 0.5-3.0 g/cm.sup.3. The
wrapper is preferably used as an overwrap for a porous
non-smokeable plugwrap tobacco rod having porosities of about
12,000 Coresta Units.
[0013] Sol gels have been applied to conventional cigarette paper
in order to reduce sidestream smoke, particularly sol gels made
from a magnesium aluminate, calcium aluminate, titania, zirconia
and aluminum oxide, as described in Canadian Patent 1,180,968 and
Canadian Patent application 2,010,575. Canadian Patent 1,180,968
describes the application of magnesium hydroxide in the form of an
amorphous gel as a cigarette paper filler component to improve ash
appearance and sidestream smoke reduction. The magnesium hydroxide
gel is coated on or applied to the fibres of the sheet of the
cigarette paper. Canadian patent application 2,010,575 describes
the use of gels produced by a solution gelation or sol-gel process
for controlling the combustion of wrappers for smoking articles.
The gels may be applied as coatings to paper fibres before the
paper is formed into wrappers. The wrappers are useful for reducing
visible sidestream smoke. The metal oxides for the sol gels may be
oxides of aluminum, titanium, zirconium, sodium, potassium or
calcium.
[0014] Published German patent application DE 3508 127 describes a
novelty type cigarette which produces a shower of sparks when
smoked. This is achieved by incorporating a granular misch metal in
the form of cerium ferrite or silico-cerium in the cigarette paper.
When the cigarette is smoked particularly in dark spaces the
burning cigarette gives off sparks along with a bright light
effect. The cerium ferrite particles incorporated in the cigarette
paper usually have a particle size of about 20 .mu.m.
[0015] Catalysts have also been directly applied to cigarette
paper, such as described in Canadian Patent 604,895 and U.S. Pat.
No. 5,386,838. Canadian Patent 604,895 describes the use of
platinum, osmium, iridium, palladium, rhodium and rhuthenium in the
cigarette paper. These metals function as oxidation catalysts to
treat vapours arising from combustion of the paper wrapper. Optimum
catalytic effect has been provided by the metal palladium. The
metal particles in a suitable medium are dispersed onto the face of
a paper wrapper before it is applied to the cigarette.
[0016] U.S. Pat. No. 5,386,838 describes the use of a sol solution
comprising a mixture of iron and magnesium as a smoke suppressive
composition. The smoke suppressive composition is made by
co-precipitating iron and magnesium from an aqueous solution in the
presence of a base. The iron magnesium composition demonstrates
high surface area of approximately 100 m.sup.2/g to approximately
225 m.sup.2/g when heated to a temperature between 100.degree. C.
and approximately 500.degree. C. The iron magnesium composition may
be added to paper pulp which is used to make smoke suppressive
cigarette paper. The iron magnesium composition apparently
functions as an oxidation catalyst and reduces the amount of smoke
produced by the burning cigarette. The catalyst may also be applied
to the tobacco, for example, as described in U.S. Pat. No.
4,248,251, palladium, either in metallic form or as a salt, may be
applied to the tobacco. The presence of palladium in tobacco
reduces the polycyclic aromatic hydrocarbons in the mainstream
smoke. Palladium is used in combination with an inorganic salt or
nitric or nitrous acid. Such nitrates include lithium, sodium,
potassium, rubidium, cesium, magnesium, calcium, strontium,
lanthanum, cerium, neodymium, samarium, europium, gadolinium,
terbium, dysprosium, erbium, scandium, manganese, iron, rhodium,
palladium, copper, zinc, aluminum, gallium, tin, bismuth, hydrates
thereof and mixtures thereof. Catalysts have also been used in
tubes to reduce sidestream smoke such as described in published PCT
application WO 98/16125.
[0017] U.S. Pat. No. 6,228,799 describes a composition comprising
cerium oxide and zirconium oxide in particulate form and having a
high surface area usually in excess of 35 m2/g. The composition is
made by co-precipitating cerium and zirconium species from a
solution at an elevated temperature, which is then separated and
dried at temperatures between 80-300.degree. C. and then calcined
at temperatures between 200 and 1,200.degree. C.
[0018] Catalytic materials have been used in aerosol types of
cigarettes which do not produce sidestream or mainstream smoke per
se, but instead a flavoured aerosol. Examples of these aerosol
cigarettes include those described in U.S. Pat. Nos. 5,040,551,
5,137,034 and 5,944,025, which use catalysts to provide the
necessary heat generation to develop the aerosol. Such catalyst
systems include oxides of cerium, palladium or platinum.
[0019] A variety of sidestream smoke control systems have been
contemplated in the prior art but none of them contemplate a
combustible cigarette paper which burns like a normal cigarette
without appreciably affecting cigarette taste and has an acceptable
ash.
SUMMARY OF THE INVENTION
[0020] In accordance with various aspects of this invention,
cigarette paper, cigarette wrapper, wrapper for a cigar or other
like tobacco products is provided for reducing visible sidestream
smoke with an improved or modified ash.
[0021] In accordance with an aspect of the invention, in a low
sidestream smoke cigarette having a conventional tobacco rod and a
combustible treatment paper, said treatment paper having a
sidestream smoke treatment composition comprising an oxygen storage
and donor metal oxide oxidation catalyst and an essentially
non-combustible finely divided particulate adjunct for said
catalyst, the improvement comprising the use of a solid solution of
particulate mixed metal oxides as said catalyst and said
adjunct.
[0022] The oxygen storage and donor metal oxide oxidation catalyst
as part of the solid solution is preferably selected from the group
consisting of lanthinum oxide, cerium oxide, praseodymium oxide,
neodymium oxide and mixtures thereof. The adjunct which is also
part of the solid solution is preferably selected from the group of
metal oxides consisting of zirconium oxide, aluminum oxide,
magnesium oxide, titanium oxide and mixtures thereof.
[0023] The solid solution of mixed metal oxides may further include
in the solid solution metal catalyst selected from the group
consisting of palladium, platinum, rhodium, tin oxide, copper
oxide, iron oxide, manganese oxide and mixtures thereof. Preferred
mixed oxides of the solid solution are cerium/lanthinum mixed
oxide, cerium/zirconium mixed oxide, cerium/zirconium/lanthinum
mixed oxide, cerium/zirconium/praseodynium mixed oxide,
cerium/zirconium/lanthinum/praseodynium mixed oxide,
cerium/zirconium/neodymium mixed oxide and mixtures thereof.
[0024] In accordance with another aspect of the invention, a low
sidestream smoke cigarette comprises a conventional tobacco rod and
a combustible treatment paper having a sidestream smoke treatment
composition, the treatment composition comprises an oxygen storage
and donor metal oxide oxidation catalyst, an essentially
non-combustible adjunct for said catalyst and a metal oxide for
modifying ash characteristics.
[0025] In accordance with another aspect of the invention, the
adjunct may comprise a mixed metal oxide or carbonate filler used
in conjunction with a zeolite based material. The zeolite based
material is preferably in an amount ranging from about 0.1% to 35%
by weight of the total dry weight of the composition, although the
amount could be higher. The mixture of metal oxides may include
mixtures of zirconium oxide, tin oxide, titanium oxide, magnesium
oxide, alumina, cerium oxide tin oxide, iron oxide, manganese
oxide, calcium carbonate, zirconium carbonate, magnesium carbonate
and mixtures thereof. The metal oxides may be of various surface
areas and most preferably either low surface area in the range of
about 5 to 15 m.sup.2/g and high surface area of over 20 m.sup.2/g.
A cerium oxide hydrate sol may be applied to the adjunct, for
example, the metal oxides to provide increase catalytic
activity.
[0026] In accordance with another aspect of the invention, the
oxygen storage and donor metal oxide oxidation catalyst material
preferably include lanthinum oxide, cerium oxide, praseodymium
oxide, neodymium oxide and mixtures thereof. Oxidation catalyst of
the precious metal and transition metal type may also be included
such a palladium, platinum, rhodium, tin oxide, copper oxide, iron
oxide, manganese oxide and mixtures thereof. These catalyst may
also be fixed on the adjunct or the ash modification material or as
part of the solid solution of the mixed oxides.
[0027] The sidestream smoke treatment composition may be
incorporated in the combustible treatment paper, coated on the
combustible treatment paper, impregnated into treatment paper or a
combination of the above steps. The treatment paper may be double
wrapped and be of the same or different compositions. One of the
double wraps may be conventional paper. Alternatively, one of the
double wraps may have a composition directed primarily to
sidestream smoke reduction and the other double wrap paper include
a composition directed towards ash modification.
[0028] In accordance with another aspect of the invention, a low
sidestream smoke cigarette comprises a conventional tobacco rod and
a combustible treatment paper having a sidestream smoke treatment
composition. The treatment composition comprises an oxygen storage
and donor metal oxide oxidation catalyst and an essentially
non-combustible high surface area adsorptive adjunct for the
catalyst incorporated in said treatment paper. A coating of calcium
carbonate is provided on an exterior surface of the treatment paper
to modify ash characteristics.
[0029] For ease of description, whenever the term cigarette is
used, it is understood to not only include smokable cigarettes but
as well any form of wrapped smokable tobacco product, such as
cigars, or the like. Whenever the term treatment paper is used, it
is understood to encompass combustible wrappers and the like which
may be used on cigarettes, cigars, and the like. The wrapper may be
used as a single layer of cigarette paper or multiple layer of
cigarette paper. The wrapper may be applied as the sole layer of
cigarette paper or as a wrap over conventional cigarette paper of a
cigarette. The treatment paper may include as its substrate
conventional cigarette paper or similar combustible product with a
wide range of porosities. The conventional tobacco rod encompasses
tobacco compositions normally used in smokable cigarettes. These
rods are to be distinguished from tobacco components used in
aerosol cigarette.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Preferred embodiments of the invention are shown in the
drawings wherein:
[0031] FIG. 1 is a schematic view of a spray technique for applying
the treatment composition to a cigarette paper;
[0032] FIG. 2 is a schematic view of extruding a film of the
treatment composition onto the cigarette paper;
[0033] FIG. 3 is a schematic view of roll coating the treatment
composition on cigarette paper;
[0034] FIG. 4 is a schematic view of the impregnation of a coating
of the treatment composition into the cigarette paper;
[0035] FIG. 5 is a schematic view of mixing the treatment
composition with the paper pulp in the manufacture of cigarette
paper;
[0036] FIG. 6 is a perspective view of a tobacco rod having the
treatment paper of this invention applied thereto;
[0037] FIG. 7 shows an alternative embodiment of FIG. 6;
[0038] FIG. 8 is a perspective view of a tobacco rod having the
treatment composition sandwiched between two layers of cigarette
paper as applied to the tobacco rod; and
[0039] FIG.b 9 is a perspective view of a double wrap for the
tobacco rod where treatment paper is applied over conventional
cigarette paper.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] In accordance with an aspect of this invention, the
sidestream smoke treatment composition provides the desired degree
of visible sidestream smoke control while at the same time
providing a suitable ash of desired characteristics. The sidestream
smoke treatment composition of this invention comprises, an oxygen
storage and donor metal oxide oxidation catalyst used in
combination with a non-combustible finely divided porous
particulate adjunct for the catalyst. As taught in applicant's
co-pending U.S. patent application Ser. No. 09/954,432 filed Sep.
18, 2001, it was unexpectantly found that when these two components
are used in combination either alone or with other constituents, a
very surprising degree of visible sidestream smoke control is
provided. It has been found that with certain types of catalytic
material and/or adjuncts, ash characteristics, such as, appearance
can sometimes be less than acceptable due to, for example,
discolouration, delamination and defoliation. In accordance with
this invention, enhancements have been made to the composition and
in particular to the catalyst and/or adjunct to modify ash
characteristics to provide for example an acceptable appearance,
acceptable strength, colour, integrity and reduction or elimination
of ash defoliation, delamination and the like.
[0041] The adjunct may be any suitable essentially non-combustible,
finely divided particulate material which does not affect the
flavour and taste of the mainstream smoke and does not give off any
undesirable odours in the sidestream vapours. The particulate
material is physically stable at the elevated temperatures of the
burning cigarette coal. The adjunct may have a low surface area
usually less than 20 m.sup.2/g and preferably 1 m.sup.2/g to 15
m.sup.2/g and most preferably 3 m.sup.2/g to 10 m.sup.2/g. It is
understood for the low surface area materials the particulates are
finely ground and are usually not porous. However, as the surface
area increases towards 20 m.sup.2/g it is understood that the
particles may be porous. Conversely the adjunct may also have a
high surface area usually greater than 20 m.sup.2/g and at this
level of surface area usually the particulate material is porous.
The porous adjunct may have pores with an average diameter of less
than 100 nm (1000 .ANG.). More preferably, the pores have an
average diameter of less than 20 nm (200 .ANG.) and even more
preferred are pores with an average diameter of 0.5 to 10 nm (5-100
.ANG.). With zeolite based materials, the pores have an average
diameter in the range of about 0.5 to 1.3 nm (5-13 .ANG.).
[0042] The particulate adjunct may have an average particle size of
less than about 30 .mu.m, more preferably less than about 20 .mu.m
and most preferably ranging from about 1 .mu.m up to about 10
.mu.m. Non-combustible materials may be porous clays of various
categories commonly used in cigarette paper manufacture, such as
the bentonite clays or treated clays having high surface areas.
Non-combustible carbon materials may also be used including milled
porous carbon fibres and particulates. Various metal oxides and/or
carbonates may be used such as porous monolithic mineral based
materials such as zirconium oxide, titanium oxides, magnesium
oxide, aluminum oxide, cerium oxide, tin oxide, iron oxide,
manganese oxide, calcium carbonate, zirconium carbonate, magnesium
carbonate and mixtures thereof, metal oxide fibres such as
zirconium fibres and other ceramics such as milled porous ceramic
fibres and mixtures thereof. In respect of cerium oxide, it has
been found that it is capable of functioning as a finely divided
adjunct and as an oxygen storage and donor cerium oxide oxidation
catalyst. Other adjunct materials include high surface area
materials such as activated carbon and zeolites.
[0043] The adjunct may also comprise high surface area highly
sorptive materials which are non-combustible, inorganic finely
divided particulate, such as molecular sieves which include
zeolites and may also comprise amorphous materials such as
silica/alumina, zirconium oxide, zirconium hydroxide and the like.
Zeolites such as silicalite zeolites, faujasites X, Y and L
zeolites, beta zeolites, Mordenite zeolites and ZSM zeolites are
acceptable. Preferred zeolites include hydrophobic zeolites and
mildly hydrophobic zeolites which have affinity for hydrophobic and
mildly hydrophobic organic compounds of such sidestream smoke
whereby water vapour is avoided. The zeolite materials provide a
highly porous structure which selectively absorbs and adsorbs
components of sidestream smoke. The highly porous structure
generally comprise macropores amongst the particles and micropores
within the particles which branch off of the macropores. It is
believed that the captured components in the macropores and
micropores in presence of the cerium oxide or other suitable
oxidation catalysts at the high temperature of the burning
cigarette, converts such captured components into oxidized
compounds which continue to be trapped in the adsorbent material or
are released as invisible gases which have sufficiently low tar and
nicotine levels so that the sidestream is invisible or at a low
desired level.
[0044] The zeolite materials may be characterized by the following
formula:M.sub.mM'.sub.nM''.sub.p[aAlO.sub.2.b
SiO.sub.2.cTO.sub.2]
wherein
[0045] M is a monovalent cation, [0046] M' is a divalent cation,
[0047] M'' is a trivalent cation, [0048] a, b, c, n, m, and p are
numbers which reflect the stoichiometric proportions, [0049] c, m,
n or p can also be zero, [0050] Al and Si are tetrahedrally
coordinated Al and Si atoms, and [0051] T is a tetrahedrally
coordinated metal atom being able to replace Al or Si, wherein the
ratio of b/a of the zeolite or the zeolite-like material, has a
value of about 5 to 300 and the micropore size is within the range
of about 0.5 to 1.3 nm (5 to 13 .ANG.).
[0052] Preferred zeolites of the above formula, have the specific
formulas of faujasites ((Na.sub.2, Ca,
Mg).sub.29[Al.sub.58Si.sub.134O.sub.384].240H.sub.2O; cubic),
.beta.-zeolites (Na.sub.n[Al.sub.nSi.sub.64-nO.sub.128] with
n<7; tetragonal), Mordenite zeolites
(Na.sub.8[Al.sub.8Si.sub.40O.sub.96].24H.sub.2O; orthorhombic), ZSM
zeolites (Na.sub.n[Al.sub.nSi.sub.96-nO.sub.192].about.16H.sub.2O
with n<27; orthorhombic), and mixtures thereof.
[0053] It is appreciated that various grades of the sorptive
material may be used. This is particularly true with gradients of
zeolites which can be custom designed to selectively adsorb, for
example, high boiling point materials, mid boiling point materials
and low boiling point materials. This can lead to layers of the
zeolite composition where the cerium oxide or other suitable
catalyst contemplated by this invention is preferably dispersed
throughout these layers. The layers may then be bound on cigarette
paper for the tobacco rod by using a binder or an adhesive which
may be, for example, polyvinylacetate, polyvinyl alcohol, carboxy
methyl cellulose (CMC), starches and casein or soya proteins, and
mixtures thereof.
[0054] The oxygen donor and oxygen storage metal oxide oxidation
catalyst may be selected from the transition metal oxides, rare
earth metal oxides, (such as scandium, yttrium, and lanthanide
metal series, i.e. lanthanum) and mixtures thereof. It is
appreciated that the catalyst may be in its metal oxide form or a
precursor of the metal oxide which, at the temperature of the
burning cigarette, is converted to a metal oxide to perform its
catalytic activities. The transition metal oxides may be selected
from oxides of the group of metals from the Periodic Table
consisting of groups IVB, VB, VIB, VIIB, VIII and IB metals and
mixtures thereof. Preferred metals from the transition metal group
are oxides of iron, copper, silver, manganese, titanium, zirconium,
vanadium and tungsten and from the rare earth group are oxides of
lanthanide metals such as oxides of lanthinum, cerium,
praseodymium, neodymium and mixtures thereof. For example, cerium
may be used in admixture with any one of the transition metals such
as Ce/Zr mixed oxide. It is appreciated that other metal oxide
oxidation catalysts may be used with the oxygen storage and oxygen
donor type of catalyst. Such other metal catalysts include precious
metals and metals from groups IIA, IVA and mixtures thereof.
Examples include palladium, platinum, rhodium, tin oxide, copper
oxide, iron oxide, manganese oxide and mixtures thereof.
[0055] The cerium catalyst precursor may be in the form of a cerium
salt such as a cerium nitrate or other dispersible forms of cerium
such as a cerium sol made up of a cerium oxide hydrate or as it is
also referred to as a cerium hydroxide which is applied in solution
or sol to the sorptive material or to a paper as a coating and
which is converted to cerium oxide at the high temperature of the
burning cigarette to then function as a catalyst. It is understood
that the sol may be a low nitrate cerium oxide hydrate sol. For
purposes of describing the invention, the term catalyst is intended
to include any catalyst precursor.
[0056] The catalyst such as, cerium oxide, is used in combination
with the adjunct material. It has been found that when the two are
used separate from one another or in spaced apart, non-adjacent
layers, the ability to control sidestream smoke is greatly reduced.
Although in certain arrangements, some sidestream smoke control can
be achieved. Preferably the catalyst is substantially adjacent the
adjunct material. This can be achieved by co-mingling the
particulate catalyst, in admixture with the adjunct, contacting a
layer of the adjunct with a catalyst layer, coating the catalyst on
the adjunct or impregnating the catalyst within or on the porous
surfaces of the adjunct, to bring about the desired surprising
sidestream smoke control properties. It should be appreciated that
many other constituents may be used in addition to the combination
of the oxygen storage and oxygen donor metal oxide oxidation
catalyst and the adjunct. Additional additives may be used to
further enhance the treatment of the sidestream smoke or alter
other characteristics of the cigarette. Such additional additives
may be mixed in with the treatment composition or used elsewhere in
the cigarette construction, providing of course that such additives
do not appreciably impact negatively on the ability of the
treatment composition to treat the sidestream smoke.
[0057] The composition may be formulated in a variety of ways which
achieve co-mingling of the cerium with the adsorptive material. For
example, the adsorptive material may be sprayed with or dipped in a
cerium salt solution such as cerium nitrate or cerium oxide hydrate
sol to impregnate the surface of the adsorptive material with
cerium material. Cerium oxide may be prepared as a separate fine
powder which is mixed with the fine powder of the adsorptive
material. It is particularly preferred that the catalyst powders
have an average particle size of less than about 30 .mu.m and
preferably less than 20 .mu.m and most preferably about 1.0 to 10
.mu.m and more preferably 6 to 10 .mu.m to ensure intimate mixing
and co-mingling of the materials.
[0058] As a general guide to selecting catalyst particle size and
surface area, it is appreciated by one skilled in the art that the
selected catalyst has a surface area which is such to ensure that
the catalyst active sites are available to the migrating sidestream
smoke components. This may result in catalyst particle size being
greater than 30 .mu.m in certain embodiments, if the catalyst
particles are properly distributed to achieve the necessary degree
of sidestream smoke component oxidation.
[0059] It has been surprisingly found that the cerium oxide,
particularly high surface area cerium oxide, is one of the few
metal oxides which can perform both functions of the invention,
namely as the oxygen storage and oxygen donor catalyst and as well
as the adjunct. The porous cerium oxide particles can be made with
the high surface areas and an average particle size required for
the adjunct. The cerium oxide is used with the cigarette paper in a
first amount as the catalyst and a second amount as the adjunct in
the treatment composition. Such amounts of the cerium oxide
correspond generally with the amounts used for the catalyst and
adjunct in accordance with other aspects of the invention to make
up the total loading. Alternatively the high surface area cerium
oxides can be used with adjuncts such as zeolites or other high
surface metal oxides such as zirconium oxide or zirconium
hydroxide.
[0060] The cerium may be formulated as a solution dispersion, such
as cerium oxide sol, or the like and applied to the sorptive
material such as zeolite. It is then dried and fired to provide
cerium oxide particles fixed on the surfaces of the adsorptive
material. When the cerium oxide particles are fixed to adjunct
surfaces such as surfaces of zeolite, the average particle size may
be less than about 1.0 .mu.m. The relative amounts of cerium oxide
fixed to the zeolite may range from about 1% to 75% by weight based
on the total equivalent cerium oxide and zeolite content. The
preferred relative amounts of cerium oxide fixed to the zeolite may
range from about 5% to 70% by weight based on the total equivalent
cerium oxide and zeolite content.
[0061] One possible method for making the combination product of
cerium oxide fixed on the surfaces of the zeolite is described in
published a co-pending application Ser. No. 60/318,878, entitled A
Process For Making Metal Oxide-Coated Microporous Materials, filed
in the U.S. Patent Office on Sep. 14, 2001, the subject matter of
which is incorporated herein by reference.
[0062] The method generally involves making a catalytic cerium
oxide-coated zeolite particulate material having at least 1% by
weight of cerium oxide coated on outer surfaces of the zeolite
particulate material, based on the total equivalent cerium oxide
and zeolite content. In one aspect, the method generally comprises
the steps of: [0063] i) combining an amount of a colloidal
dispersion of cerium oxide hydrate (cerium hydroxide) with a
compatible zeolite particulate material to form a slurry, the
amount of the colloidal dispersion being sufficient to provide,
when heat treated as per step (ii), greater than 20% by weight of
the cerium oxide, the zeolite particulate material having an
average pore size of less than 20 .ANG. and the colloidal
dispersion having an average particle size of at least 20 .ANG., to
position thereby, the colloidal dispersion on the outer surfaces of
the zeolite; and [0064] ii) heat treating the slurry firstly, at
temperatures below about 200.degree. C. and secondly, above about
400.degree. C., to fix the resultant cerium oxide on the outer
surfaces of the zeolite particulate material, to provide a free
flowing bulk particulate.
[0065] Some of the combinations for the treatment composition can
result in what could be considered as unacceptable ash appearance.
Unacceptable ash appearance characteristics include delamination,
defoliation, ash smear, oily appearance and color. It was thought
that various ash modifiers could be added to the paper to improve
ash appearance. Such ash modifiers include metal oxides and/or
carbonates such as zirconium oxide, titanium oxides, magnesium
oxide, aluminum oxide, cerium oxide, tin oxide, iron oxide,
manganese oxide, calcium carbonate, zirconium carbonate, magnesium
carbonate and mixtures thereof.
[0066] It is been found that the treatment composition may require
modifications to improve ash characteristics. Such modifications
may include selection of a particular chemical or physical type of
oxygen donor/oxygen storage catalyst and/or of the type of adjunct.
In particular to enhance the color of the ash so that it is more a
white or gray rather than a dark coal color, it has been found that
reduced amounts of zeolite base material for the adjunct is
appropriate. The reduce amount of zeolite material based on the dry
weight of the paper is preferably less than 35% by weight and more
preferably less than 25% by weight and most preferably less than
15% by weight. It is appreciated that other types of fillers have
to be added to compensate for the reduced amount of zeolite based
adjunct. Suitable substitute metal oxides and/or carbonates include
zirconium oxide, titanium oxides, magnesium oxide, aluminum oxide,
cerium oxide, tin oxide, iron oxide, manganese oxide, calcium
carbonate, zirconium carbonate, magnesium carbonate and mixtures
thereof. Low or high surface area cerium/zirconium mixed oxides as
a solid solution are preferred. Such adjuncts may be made for
example by co-precipitating zirconium and cerium species, drying
the precipitate and then firing to form a crystalline solid
solution product of high surface area cerium oxide and zirconium
oxide. The ratio of cerium oxide to zirconium oxide in this
crystalline structure may range from about 5:95 through to 95:5.
Alternatively, the ratio may range from about 20:80 to 80:20 and
most preferred ranging from about 50:50 to 80:20. This material in
its high surface area form also has catalytic properties and also
provides for oxygen storage and donor properties where the
zirconium oxide functions as the adjunct for the cerium oxide.
[0067] In respect of the catalyst selection, there has also found
that combinations with cerium oxide contribute to a better ash
appearance. For example cerium oxide may be deposited on high
surface area cerium oxide, cerium oxide hydrate deposited on high
surface area cerium/zirconium oxides, cerium oxide hydrate deposit
and dried on a high surface area cerium oxide particle.
Furthermore, oxidation catalyst of the aforementioned precious
metal or transition metal types may be combined with the cerium
based materials such as palladium, platinum, rhodium, tin oxide,
copper oxide, iron oxide, manganese oxide, and mixtures
thereof.
[0068] Solid solutions of mixed metal oxides are particularly
preferred as the oxygen donor catalyst because of an improved
lighter colour ash. The solid solution of the mixed metal oxides
includes the oxygen donor oxygen storage oxidation catalyst and the
adjunct. Preferred metal oxides in a solid solution as the oxygen
donor oxygen storage material include lanthinum oxide, cerium
oxide, praseodymium oxide, neodymium oxide and mixtures thereof.
The preferred metal oxides as adjuncts include zirconium oxide,
aluminum oxide, magnesium oxide, titanium oxide and mixtures
thereof. Examples of these solid solutions include cerium/lanthinum
mixed oxide, cerium/zirconium mixed oxide,
cerium/zirconium/lanthinum mixed oxide,
cerium/zirconium/praseodynium mixed oxide,
cerium/zirconium/lanthinum/praseodynium mixed oxide,
cerium/zirconium/neodymium mixed oxide. These solid solutions of
mixed oxides and other mixed oxides are readily available as
commercial grade catalyst and are available from any of a number of
catalyst suppliers. Other alternatives to the solid solutions
include physical mixtures of zirconium oxide, aluminum oxide,
magnesium oxide, titanium oxide with a solid solution for example
cerium/zirconium mixed oxide solid solution. Other solid solutions
and mixed oxides contemplated by this invention include
cerium/aluminum mixed oxide, cerium/magnesium mixed oxide,
cerium/titanium mixed oxide.
[0069] The oxidation catalysts which maybe included in the solid
solutions are usually present in trace amounts. Such catalyst
include palladium, platinum, rhodium, tin oxide, copper oxide, iron
oxide, manganese oxide and mixtures thereof. They are usually
included in the solid solutions at levels less than 1% by weight of
the total solid solution. A preferred combination and in respect of
the solid solution with trace amounts of other oxidation catalyst
is a combination of the above catalyst with a solid solution of
cerium/zirconium mixed oxide. It is preferred that the above
oxidation catalyst either individually or mixtures thereof be
included in the solid solution. Although alternatively it is
understood that the above catalyst or mixtures thereof maybe
applied to the surfaces of the cerium/zirconium mixed oxide solid
solution particulate material.
[0070] Multiple purpose solid solution of mixed oxides include
ceria/zirconia/magnesia/titania/ where ceria makes up about 5% to
about 75% of the solid solution.
[0071] It has also been found that a coating on the wrapper of
particulate calcium carbonate is useful in improving ash
characteristics. As previously described the treatment composition
maybe incorporated or coated on a wrapper which is the sole wrapper
for the tobacco rod. As noted above, one approach to improving ash
is to reduce the amount of the absorptive adjunct such a zeolites
and substitute therefor a selected metal oxide. Alternatively it
has been found that particularly with single wrappers having
incorporation of the treatment composition, a coating of calcium
carbonate on the exterior of the wrapper greatly improves the ash
particularly from the stand point of appearance. It is quite
surprising that a coating of particulate calcium carbonate could
have this effect on improving the ash characteristics. Perhaps the
calcium carbonate chemically or physically binds constituents in
the wrapper to produce a more uniform light to gray coloured ash.
The particulate calcium carbonate maybe slurried with a suitable
binder for coating on the wrapper. Suitable binders include those
commonly used in coating calcium carbonate on wrapper materials
such a polyvinlylalcohols, starches, CMC, casein, soya, binding
clays and other acceptable binders or glues. The particulate
calcium carbonate has a particle size of that normally associated
with its use as a filler in manufacture of cigarette paper. The
particle size is therefore usually below 10 .mu.m and preferably
above 3 .mu.m. Although some grades of calcium carbonate less than
1 .mu.m may also be useful.
[0072] The surprising activity of the sidestream smoke treatment
composition permits its use in cigarette papers having a wide range
of porosities. It has also been found that the composition does not
have to be used in cigarette papers that just have high porosities.
The treatment composition works equally well in papers with very
low porosities of about 0.5 through to very high porosities of
about 1,000 Coresta units. Preferred porosities are usually less
than 200 Coresta units and most preferred porosities are usually in
the range of about 15 to 60 Coresta units. It is appreciated that
the paper may be used as a double or multiple wrap. The paper may
be applied as an outer wrap over a cigarette having conventional
cigarette paper. It is appreciated that depending upon the
porosity, certain combinations of the catalyst and adjunct may work
better than others.
[0073] The composition may be simply sprayed onto either side or
both sides of the cigarette paper and absorbed into the paper. As
shown in FIG. 1, the paper 10 is conveyed in the direction of arrow
12. The treatment composition 14 as a slurry is sprayed by spray
nozzle 16 onto the paper 10 to provide a coating 18 which is dried
on the paper. Alternatively, the composition may be extruded as a
film to the surface of the paper and may be used as a single or
multiple wrap. As shown in FIG. 2, a film coating device 20
contains the slurried treatment composition 14. The film coater 20
lays a thin film 22 on the paper 10 which is conveyed in the
direction of arrow 12. The film is dried to provide a coating 24 on
the paper 10. With these arrangements, it is quite surprising that
the visual sidestream smoke from a burning cigarette virtually
disappears. The treatment composition may be applied to a
conventional cigarette on the exterior of the cigarette paper.
[0074] Coating may be achieved by a roller applicator 26, as shown
in FIG. 3. The treatment composition 14 is applied as a layer 28 on
the roller 30. A doctor knife 32 determines the thickness of a
layer 34 which is then laid onto the paper 10 which is conveyed in
the direction of arrow 12. The layer is then dried to form a
coating 36 on the paper 10.
[0075] Impregnation is achieved by using the coating roller 24 of
FIG. 4 and the resultant layer 36 with paper 10 is passed in the
direction of arrow 12 through pressure rollers 38 and 40 which
force the layer of material into the paper 10 to thereby impregnate
constituents of the treatment composition into the paper.
[0076] It is also understood by one of skill in the art that
various other coating processes including transfer coating
processes, may be used for making the treatment paper of the
invention. In the transfer coating process, Mylar.TM. sheet or
other suitable continuous sheet may be used to transfer a coating
composition from the Mylar.TM. sheet to the surface of the
cigarette paper. This type of transfer coating is useful when the
substrate sheet may not readily accept the roll coating of a
composition due to physical strength characteristics of the paper
or the like.
[0077] A further alternative is to incorporate the treatment
composition into the manufacture of paper. The composition may be
introduced to the paper furnish as a slurry. With reference to FIG.
5, the treatment composition in the furnish 42 is stirred by
stirrer 44 to form a slurry in the tank 46. The slurry is
transferred in the conventional paper making manner and is laid as
a layer 48 on a moving conveyor 50 to form the resultant cigarette
paper 52. As a result the treatment composition is incorporated in
the final paper product.
[0078] Another alternative is to sandwich the treatment composition
between paper layers to form a double cigarette paper wrap on
tobacco rods. For example, the composition may be applied such as
by the spraying technique of FIG. 1 on the interior of the outer
paper and/or the exterior of the inner paper. Once the two papers
are applied to the tobacco rod the composition as a layer is
sandwiched between the two papers. Each paper may be of half of the
thickness of conventional cigarette paper so that the double wrap
does not add appreciably to the overall diameter of the cigarette
as is readily handled by cigarette making machines.
[0079] With reference to FIG. 6, the tobacco rod 54 has, for
example, the cigarette paper 10 wrapped therearound with the
coating 18 on the outside of the paper. Conversely, as shown in
FIG. 7, the cigarette paper 10 can be applied with the coating 18
on the inner surface of the paper adjacent the tobacco rod 54.
[0080] Another alternative, as shown in FIG. 8, is to sandwich the
coating 18 between cigarette papers 56 and 58. The papers 56 and 58
with the intermediate coating 18 may be formed as a single
cigarette wrapper which is applied to the tobacco rod 54. A further
alternative is shown in FIG. 9 where the tobacco rod 54 is covered
with conventional cigarette paper 60. Over the conventional paper
60 is the cigarette paper 52 of FIG. 5 with the treatment
composition incorporated therein. It is also appreciated that paper
52 with the treatment composition incorporated therein may be
applied directly to the tobacco rod 54.
[0081] In yet another alternative embodiment of the invention,
various combinations for the sidestream smoke treatment paper may
be provided in a double wrap configuration for example, a coated
paper of FIG. 7 could be used as the inner layer of paper and a
different paper could be used as the outer layer of the double wrap
which could be conventional paper. The inner layer paper could also
be a paper having the treatment composition incorporated therein
such as that of FIG. 9. The inner layer paper could be designed to
provide for sidestream smoke reduction by including all the
necessary components of the composition such an oxygen storage and
donor metal oxide oxidation catalyst and the non-combustible
adjunct for the catalyst. Preferred examples of this type of
composition includes a high surface area, cerium/zirconium mixed
oxide with zeolite and optionally enhanced with an oxidation
catalyst such as platinum or palladium. In a double wrap system,
the amount of zeolite may exceed 30% and may be in the range for
example of 50% to 60% by weight.
[0082] The outer layer of the double wrap may have a different
composition and be designed to provide for ash modifications to
achieve desired characteristics. For example, the outer paper may
be designed to enhance not only ash appearance but as well modify
the burn rate of the cigarette and also minimized if not eliminate
flare ups on lightning and puffing of the cigarette. The outer
layer may include, for example, metal oxides such as low surface
area cerium oxide, solid solution of cerium oxide/zirconium oxide,
alumina, zirconium oxide, titanium oxide, tin oxide and the like.
In addition cerium oxide hydrate may be coated on the metal oxide
materials of the outer layer to ensure sufficient oxygen is present
to support combustion of the outer layer of the cigarette. The two
layers when combined as a double wrap provide effective control of
visible sidestream smoke. The adjacent papers burn evenly to
produce desired ash and the outer paper may function to minimize or
eliminate the highly active oxygen donor material from causing
flare ups.
[0083] The double wrap feature of the invention provides
significant flexibility in the design of a low sidestream smoke
cigarette. The individual sheets of the double wrap design has the
selected treatment composition impregnated, coated or incorporated
in the respective sheet. Alternatively sheets that have a treatment
composition incorporated therein may also be coated with the same
or different treatment composition to further enhance the
sidestream smoke control and/or ash modification. To demonstrate
such flexibility in the design of the low sidestream smoke
cigarette, exemplary treatment composition for the inner and outer
papers are as follows:--
[0084] Outer paper [0085] i) High surface area of cerium/zirconium
mixed oxide (75:25)+low surface area zirconium oxide; [0086] ii)
High surface area alumina coated with cerium hydrate; [0087] iii)
Low surface area cerium oxide coated with cerium hydrate; [0088]
iv) High surface area zirconium oxide coated with cerium hydrate;
or [0089] v) High surface area cerium/zirconium mixed oxide
(25:75).
[0090] Inner paper [0091] i) High surface area of cerium/zirconium
mixed oxide (75:25) enhanced with palladium catalyst+zeolite
enhance with palladium catalyst; [0092] ii) High surface area of
cerium/zirconium mixed oxide (75:25)+zeolite enhanced with
palladium; [0093] iii) High surface area of cerium/zirconium mixed
oxide (75:25)+zeolite where the cerium/zirconium mixed oxide is
enhanced with palladium catalyst; or [0094] iv) High surface area
of cerium/zirconium mixed oxide (75:25)+zeolite where the
cerium/zirconium mixed oxide is enhanced with platinum and tin
catalyst.
[0095] These various compositions for the inner and outer papers
may be combined in various combinations to provide for sidestream
smoke control and ash improvement.
[0096] The preferred combination is a solid solution of high
surface area cerium/zirconium mixed oxide (75:25) and zirconium
oxide for the outer paper. For the inner paper the preferred
treatment composition is a solid solution of high surface area
cerium/zirconium mixed oxide (75:25) enhanced with palladium
catalyst plus zeolite enhanced with palladium catalyst. On a dry
weight basis in the outer paper coating formulation has 25% of high
surface area cerium/zirconium mixed oxide and 75% of low surface
area zirconium oxide. The inner paper on a dry weight basis has
about 44% of high surface area cerium/zirconium mixed oxide and 56%
of zeolite both enhanced with palladium.
[0097] As is appreciated by one of skill in the art, the
aforementioned procedures for providing the sidestream smoke
treatment composition within or onto a desired cigarette paper may
be varied with respect to the loadings provided and the number of
wraps used on a tobacco rod. For example, two or more papers with
various loadings of the composition, on both sides of the papers,
may be used such that the loading to one side is reduced, making
the coating application easier.
[0098] With any of these combinations, it has been surprisingly
found that visible sidestream smoke is virtually eliminated. At the
same time, the cigarette paper demonstrates conventional ashing
characteristics. It is particularly surprising that the simple
application of the composition to the exterior of the cigarette
paper can minimize to an almost undetectable level, visible
sidestream smoke.
[0099] It is appreciated that depending upon the manner in which
the composition is used and applied to a cigarette, various
processing aids and mixtures thereof may be required to facilitate
the particular application of the treatment composition. Such
processing aids include laminating materials such as
polyvinylalcohol, starches, CMC, casein, soya and other types of
acceptable glues, various types of binding clays, inert fillers,
whiteners, viscosity modying agents, inert fibrous material such as
zirconium fibres and zirconium/cerium fibres, such as described in
U.S. application Ser. No. 60/318,614 entitled Zirconium/Metal Oxide
Fibres, filed Sep. 13, 2001, the subject matter of which is
incorporated hereby by reference.
[0100] Penetrating agents may also be employed to carry the
composition into the paper. Suitable diluents such as water are
also used to dilute the composition so that it may be spray coated,
curtain coated, air knife coated, rod coated, blade coated, print
coated, size press coated, roller coated, slot die coated,
technique of transfer coating and the like onto a conventional
cigarette paper.
[0101] Desirable loadings of the treatment composition onto or into
the cigarette paper, wrapper or the like is preferably in the range
of from about 2.5 g/m.sup.2 to about 125 g/m.sup.2. Most preferably
the loading is in the range of about 2.5 g/m.sup.2 to about 100
g/m.sup.2. Expressed as a percent by weight, the paper may have
from about 10% to 500% by weight and most preferably about 10% to
400% by weight of the treatment composition. While these loadings
are representative for single paper, it is understood by one
skilled in the art that these total loadings may be provided with
the use of two or more papers.
[0102] The sidestream smoke reduction composition is used normally
as a water slurry of the composition. The make up of the dry
composition which can be made into a slurry, may vary depending on
its use as a paper coating, incorporation or impregnation. For
example the incorporation formulation may contain by weight from
about 10% to 33% of a cerium based catalyst, 20% to 62% of an
adjunct and 10% to 75% of an ash modifier. Another alternative may
contain by weight about 10% to 25% of a cerium based catalyst, 40%
to 55% of an adjunct and 20% to 50% of a zeolite which is other
than the adjunct.
[0103] The slurry may be incorporated in the furnish of the paper
in the paper making process, or is coated onto the paper by various
coating processes or impregnated into the paper by various
impregnating methods. The preferred average particle size of the
catalyst and adjunct for the slurry is in the range of about 1
.mu.m to about 30 .mu.m and most preferably about 1 .mu.m to about
10 .mu.m. The preferred relative amounts of catalyst fixed to the
adjunct may range from about 1% to 75% for cerium, more preferably
from about 10% to 70%, and even more preferably from about 20% to
70% by weight based on the total equivalent catalyst and adjunct
content. Less than 1% of other catalyst such as precious metal
catalyst may be fixed to the adjunct.
[0104] Although preferred embodiments of the invention have been
described herein in detail, it will be understood by those skilled
in the art that variations may be made thereto without departing
from the spirit of the invention or the scope of the appended
claims.
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