Molecular sieve abstract
Smoking articles and filters, which involve the use of carbon-coated
molecular sieve sorbents are provided. The carbon-coated molecular
sieve sorbent has a carbon coating within pores of a mesoporous
molecular sieve. The carbon-coated molecular sieve sorbent provides
selective adsorption of one or more constituents from mainstream
smoke, such as acrolein or 13-butadiene. Thus, certain constituents
from cigarette smoke will be selectively removed, while maintaining
other constituents, such as those that contribute to flavor. Methods
for making cigarette filters and smoking articles using the carbon-coated
molecular sieve sorbent, as well as methods for smoking a cigarette
comprising the carbon-coated molecular sieve sorbent, are also provided.
Molecular sieve claims
What is claimed is:
1. A smoking article comprising a carbon-coated molecular sieve
sorbent having a carbon coating within pores of a mesoporous molecular
sieve substrate, wherein the carbon-coated molecular sieve sorbent
is capable of removing at least one selected constituent from mainstream
smoke.
2. The smoking article of claim 1 wherein the smoking article
is selected from the group consisting of cigarettes, pipes, cigars
and non-traditional cigarettes.
3. The smoking article of claim 1 wherein the smoking article
is a cigarette.
4. The smoking article of claim 1 wherein the carbon-coated molecular
sieve sorbent is located in a filter.
5. The smoking article of claim 4 wherein the filter is a mono
filter, a dual filter, a triple filter, a cavity filter, a recessed
filter or a free-flow filter.
6. The smoking article of claim 4 wherein the filter comprises
cellulose acetate tow, cellulose paper, mono cellulose, mono acetate,
or combinations thereof.
7. The smoking article of claim 4 wherein the carbon-coated molecular
sieve sorbent is incorporated into one or more cigarette filter
parts selected from the group consisting of shaped paper insert,
a plug, a space, cigarette filter paper, and a free-flow sleeve.
8. The smoking article of claim 4 wherein the carbon-coated molecular
sieve sorbent is incorporated with cellulose acetate fibers forming
a plug or a free-flow filter element.
9. The smoking article of claim 4 wherein the carbon-coated molecular
sieve sorbent is incorporated with polypropylene fibers forming
a plug or free-flow filter element.
10. The smoking article of claim 4 wherein the carbon-coated molecular
sieve sorbent is incorporated in at least one of a mouthpiece filter
plug, a first tubular filter element adjacent to the mouthpiece
filter plug, and a second tubular filter element adjacent to the
first tubular element.
11. The smoking article of claim 4 wherein the carbon-coated molecular
sieve sorbent is incorporated in at least one part of a three-piece
filter including a mouthpiece filter plug, a first filter plug adjacent
to the mouthpiece filter plug, and a second filter plug adjacent
to the first filter plug.
12. The smoking article of claim 1 wherein the mesoporous molecular
sieve substrate is selected from the group consisting of a silicate,
a mesoporous aluminosilicate, a silica gel, an aluminophosphate,
and mixtures thereof.
13. The smoking article of claim 1 wherein the mesoporous molecular
sieve substrate is mesoporous silicate selected from the group consisting
of MCM framework type, SBA framework type, and mixtures thereof.
14. The smoking article of claim 1 wherein the mesoporous molecular
sieve substrate is SBA-15.
15. The smoking article of claim 1 wherein the carbon coating
comprises activated carbon.
16. The smoking article of claim 1 wherein the carbon-coating
comprises carbonized sugar.
17. The smoking article of claim 1 wherein the carbon-coated molecular
sieve sorbent selectively removes from mainstream smoke at least
one constituent, selected from the group consisting of aldehyde,
carbon monoxide, 13-butadiene, isoprene, acrolein, acrylonitrile,
hydrogen cyanide, o-toluidine, 2-naphtylamine, nitrogen oxide, benzene,
N-nitrosonornicotine, phenol, catechol, benz(a)anthracene, benzo(a)pyrene,
and combinations thereof.
18. The smoking article of claim 17 wherein the carbon-coated
molecular sieve sorbent selectively removes at least one of acrolein
and 13-butadiene from mainstream smoke to a greater extent than
nicotine.
19. The smoking article of claim 1 wherein the average pore size
of the carbon-coated molecular sieve sorbent is (i) larger than
at least one selected constituent of mainstream smoke and (ii) smaller
than at least one unselected constituent of mainstream smoke.
20. The smoking article of claim 1 wherein the average pore size
of the carbon-coated molecular sieve sorbent is less than about
100 .ANG..
21. The smoking article of claim 1 wherein the average pore size
of the carbon-coated molecular sieve sorbent is less than about
20 .ANG..
22. The smoking article of claim 1 wherein the carbon-coated molecular
sieve sorbent is in particle form having an average particle size
of from about 20 mesh to about 60 mesh.
23. The smoking article of claim 1 comprising from about 10 mg
to about 300 mg of the carbon-coated molecular sieve sorbent.
24. The smoking article of claim 1 comprising from about 100 mg
to about 200 mg of the carbon-coated molecular sieve sorbent.
25. A cigarette filter comprising carbon-coated molecular sieve
sorbent having a carbon coating within pores of a mesoporous molecular
sieve substrate, wherein the carbon-coated molecular sieve sorbent
is capable of removing at least one selected constituent from mainstream
smoke.
26. The cigarette filter of claim 25 wherein the filter is a mono
filter, a dual filter, a triple filter, a cavity filter, a recessed
filter, or a free-flow filter.
27. The cigarette filter of claim 25 wherein the filter comprises
cellulose acetate tow, cellulose paper, mono cellulose, mono acetate,
and combinations thereof.
28. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is incorporated into one or more cigarette
filter parts selected from the group consisting of shaped paper
insert, a plug, a space, cigarette filter paper, and a free-flow
sleeve.
29. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is incorporated with cellulose acetate fibers
forming a plug or a free-flow filter element.
30. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is incorporated with polypropylene fibers
forming a plug or free-flow filter element.
31. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is incorporated in at least one of a mouthpiece
filter plug, a first tubular filter element adjacent to the mouthpiece
filter plug, and a second tubular filter element adjacent to the
first tubular element.
32. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is incorporated in at least one part of
a three-piece filter including a mouthpiece filter plug, a first
filter plug adjacent to the mouthpiece filter plug, and a second
filter plug adjacent to the first filter plug.
33. The cigarette filter of claim 25 wherein the mesoporous molecular
sieve substrate is selected from the group consisting of a silicate,
a mesoporous aluminosilicate, a silica gel, an aluminophosphate,
and mixtures thereof.
34. The cigarette filter of claim 25 wherein the mesoporous molecular
sieve substrate is mesoporous silicate selected from the group consisting
of MCM framework type, SBA framework type, and mixtures thereof.
35. The cigarette filter of claim 25 wherein the mesoporous molecular
sieve substrate is SBA-15.
36. The cigarette filter of claim 25 wherein the carbon coating
comprises activated carbon.
37. The cigarette filter of claim 25 wherein the carbon coating
comprises carbonized sugar.
38. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent selectively removes from mainstream smoke
at least one constituent selected from the group consisting of aldehyde,
carbon monoxide, 13-butadiene, isoprene, acrolein, acrylonitrile,
hydrogen cyanide, o-toluidine, 2-naphtylamine, nitrogen oxide, benzene,
N-nitrosonornicotine, phenol, catechol, benz(a)anthracene, benzo(a)pyrene,
and combinations thereof.
39. The cigarette filter of claim 38 wherein the carbon-coated
molecular sieve sorbent selectively removes at least one of acrolein
and 13-butadiene from mainstream smoke to a greater extent than
nicotine.
40. The cigarette filter of claim 25 wherein the average pore
size of the carbon-coated molecular sieve sorbent is (i) larger
than at least one selected constituent of mainstream smoke and (ii)
smaller than at least one unselected constituent of mainstream smoke.
41. The cigarette filter of claim 25 wherein the average pore
size of the carbon-coated molecular sieve sorbent is less than about
100 .ANG..
42. The cigarette filter of claim 25 wherein the average pore
size of the carbon-coated molecular sieve sorbent is less than about
20 .ANG..
43. The cigarette filter of claim 25 wherein the carbon-coated
molecular sieve sorbent is in particle form having an average particle
size of from about 20 mesh to about 60 mesh.
44. The cigarette filter of claim 25 comprising from about 10
mg to about 300 mg of the carbon-coated molecular sieve sorbent.
45. The cigarette filter of claim 25 comprising from about 100
mg to about 200 mg of the carbon-coated molecular sieve sorbent.
46. A method for manufacturing a cigarette filter, comprising incorporating
a carbon-coated molecular sieve sorbent having a carbon coating
within pores of a mesoporous molecular sieve substrate into a cigarette
filter, wherein the carbon-coated molecular sieve sorbent is capable
of removing at least one selected constituent from mainstream smoke.
47. The method of claim 46 wherein the filter is selected from
the group consisting of a mono filter, a dual filter, a triple filter,
a cavity filter, a recessed filter, and a free-flow filter.
48. A method of making a cigarette, the method comprising: (i)
providing a cut filler to a cigarette making machine to form a tobacco
column; (ii) placing a paper wrapper around the tobacco column to
form a tobacco rod; and (iii) attaching the cigarette filter of
claim 25 to the tobacco rod to form the cigarette.
49. The method of smoking the cigarette of claim 3 comprising
lighting the cigarette to form smoke and drawing the smoke through
the cigarette, wherein during the smoking of the cigarette, the
carbon-coated molecular sieve sorbent selectively removes one or
more selected constituents from mainstream smoke.
50. The method of claim 49 wherein the carbon-coated molecular
sieve sorbent selectively removes from mainstream smoke a constituent
selected from the group consisting of aldehyde, carbon monoxide,
13-butadiene, isoprene, acrolein, acrylonitrile, hydrogen cyanide,
o-toluidine, 2-naphtylamine, nitrogen oxide, benzene, N-nitrosonornicotine,
phenol, catechol, benz(a)anthracene, benzo(a)pyrene, and mixtures
thereof.
51. The method of claim 49 wherein the carbon-coated molecular
sieve sorbent selectively removes acrolein from mainstream smoke
to a greater extent than nicotine.
52. The method of claim 49 wherein the carbon-coated molecular
sieve sorbent selectively removes 13-butadiene from mainstream
smoke to a greater extent than nicotine.
Molecular sieve description
BACKGROUND
[0001] Certain filter materials have been suggested for incorporation
into cigarette filters, including cotton, paper, cellulose, and
certain synthetic fibers. However, such filter materials mainly
remove particulate and condensable components from tobacco smoke.
Thus, they may not be optimal for the removal of gaseous components
from tobacco smoke, e.g., volatile organic compounds.
SUMMARY OF THE INVENTION
[0002] Carbon-coated molecular sieve sorbents for removing one
or more selected constituents from mainstream smoke are provided.
In a preferred embodiment, it is possible to selectively remove
one or more constituents from mainstream smoke, such as acrolein
or 13-butadiene, while retaining other constituents, such as those
relating to flavor.
[0003] In one embodiment, a smoking article is provided, which
comprises a carbon-coated molecular sieve sorbent, wherein the carbon-coated
molecular sieve sorbent has a carbon coating within pores of a mesoporous
molecular sieve substrate. Examples of smoking articles include,
but are not limited to the group consisting of cigarettes, pipes,
cigars and non-traditional cigarettes. Preferably, the smoking article
is a cigarette and the carbon-coated molecular sieve sorbent is
located in a filter of the smoking article.
[0004] In an embodiment, a cigarette filter is provided, which
comprises carbon-coated molecular sieve sorbent, wherein the carbon-coated
molecular sieve sorbent has a carbon coating within pores of an
inorganic mesoporous molecular sieve substrate. Examples of cigarette
filters include, but are not limited to a mono filter, a dual filter,
a triple filter, a cavity filter, a recessed filter, or a free-flow
filter. In an embodiment, the filter comprises cellulose acetate
tow, cellulose paper, mono cellulose, mono acetate, and combinations
thereof. In another embodiment, the carbon-coated molecular sieve
sorbent is incorporated into one or more cigarette filter parts
selected from the group consisting of: shaped paper insert, a plug,
a space, cigarette filter paper, or a free-flow sleeve. In yet another
embodiment, the carbon-coated molecular sieve sorbent is incorporated
with cellulose acetate fibers forming a plug or a free-flow filter
element.
[0005] Preferably, the carbon-coated molecular sieve sorbent is
incorporated with cellulose acetate fibers forming a plug or free-flow
filter element. In another preferred embodiment, the carbon-coated
molecular sieve sorbent is incorporated in at least one of a mouthpiece
filter plug, a first tubular filter element adjacent to the mouthpiece
filter plug, and a second tubular filter element adjacent to the
first tubular element. In an embodiment, the carbon-coated molecular
sieve sorbent is incorporated in at least one part of a three-piece
filter including a mouthpiece filter plug, a first filter plug adjacent
to the mouthpiece filter plug, and a second filter plug adjacent
to the first filter plug.
[0006] In another embodiment, methods of manufacturing a cigarette
filter are provided, which comprise incorporating a carbon-coated
molecular sieve sorbent having a carbon coating within pores of
an inorganic mesoporous molecular sieve substrate into a cigarette
filter, wherein the carbon-coated molecular sieve sorbent is capable
of sorbing at least one selected constituent from mainstream smoke.
[0007] In a further embodiment, methods of making a cigarette are
provided, which comprise (i) providing a cut filler to a cigarette
making machine to form a tobacco column; (ii) placing a paper wrapper
around the tobacco column to form a tobacco rod; and (iii) attaching
a cigarette filter having a carbon-coated molecular sieve sorbent
to the tobacco rod to form the cigarette.
[0008] In another embodiment, methods of smoking the cigarette
having a carbon-coated molecular sieve sorbent are provided, which
comprise lighting the cigarette to form smoke and drawing the smoke
through the cigarette, wherein during the smoking of the cigarette,
the carbon-coated molecular sieve sorbent selectively sorbs one
or more selected constituents from mainstream smoke.
[0009] In an embodiment, the mesoporous molecular sieve substrate
is selected from the group consisting of a silicate, a silica gel,
a mesoporous aluminosilicate, an aluminophosphate, and mixtures
thereof. Preferably, the inorganic molecular sieve substrate is
mesoporous silicate selected from the group consisting of mesoporous
MCM and SBA framework type materials and mixtures thereof.
[0010] In an embodiment of the invention, the carbon coating comprises
activated carbon, or the carbon-coating comprises carbonized sugar.
[0011] Preferably, the carbon-coated molecular sieve sorbent selectively
removes acrolein, 13-butadiene, or both from mainstream smoke to
a greater extent than nicotine.
[0012] In another preferred embodiment, the average pore size of
the carbon-coated molecular sieve sorbent is larger than at least
one selected constituent of mainstream smoke and is smaller than
at least one unselected constituent of mainstream smoke. Preferably,
the average pore size of the carbon-coated molecular sieve sorbent
is less than about 20 .ANG., more preferably the average pore size
of the carbon-coated molecular sieve sorbent is less than about
10 .ANG.. In a further embodiment, the carbon-coated molecular sieve
sorbent is in particle form having an average particle size of from
about 20 mesh to about 60 mesh.
[0013] In an embodiment, the smoking article or filter comprises
from about 10 mg to about 300 mg of the carbon-coated molecular
sieve sorbent, or preferably from about 100 mg to about 200 mg of
the carbon-coated molecular sieve sorbent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a partially exploded perspective view of a cigarette
incorporating one embodiment wherein folded paper containing carbon-coated
molecular sieve sorbent is inserted into a hollow portion of a tubular
filter element of the cigarette.
[0015] FIG. 2 is partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in folded paper and inserted into a hollow portion of a first free-flow
sleeve of a tubular filter element next to a second free-flow sleeve.
[0016] FIG. 3 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a plug-space-plug filter element.
[0017] FIG. 4 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a three-piece filter element having three plugs.
[0018] FIG. 5 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a four-piece filter element having a plug-space-plug arrangement
and a hollow sleeve.
[0019] FIG. 6 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a three-part filter element having two plugs and a hollow sleeve.
[0020] FIG. 7 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a two-part filter element having two plugs.
[0021] FIG. 8 is a partially broken-away perspective view of another
embodiment wherein carbon-coated molecular sieve sorbent is incorporated
in a filter element which may be used in a smoking article.
[0022] FIG. 9 is an adsorption-desorption isotherm of argon on
parent SBA-15 silicate substrate at 87.29 K wherein the inset shows
the BJH pore size distribution calculated from the desorption branch
of the isotherm.
[0023] FIG. 10 is an adsorption-desorption isotherm of argon on
carbon-coated SBA-15 (Sample 1) at 87.29 K wherein the inset shows
the BJH pore size distribution calculated from the desorption branch
of the isotherm.
[0024] FIG. 11 is a BJH pore size distribution calculated from
the desorption branch of the isotherm of argon at 87.29 K on Sample
1 with varying sucrose loading.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] Generally, methods, smoking articles and filters for selective
removal of certain selected constituents from mainstream smoke are
provided. One embodiment relates to a smoking article or filter,
comprising a carbon-coated molecular sieve sorbent. Methods for
making such smoking articles and filters, as well as methods of
smoking such cigarettes, also are provided.
[0026] By "selective removal" is meant that certain constituents
are at least partially removed from mainstream smoke, while other
constituents are not substantially removed. The term "selective"
also encompasses preferential removal of certain constituents from
mainstream smoke, i.e. where more than one constituent may be removed,
but where one constituent is removed to a greater extent than another
constituent.
[0027] It has been found that naturally hydrophilic molecular sieve
surfaces may be made more adsorptive to hydrophobic compounds, such
as certain organic constituents of mainstream smoke, by coating
molecular sieve substrates with carbon. The adsorptive ability of
carbon is combined with the size selectively of the molecular sieve
to selectively remove certain selected constituents from mainstream
smoke. With reference to a cigarette, 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 smoking article during smoking.
[0028] In other embodiments, smoking articles, such as cigarettes,
pipes, and cigars, as well as non-traditional cigarettes, are provided.
Non-traditional cigarettes include, for example, cigarettes for
electrical smoking systems as described in commonly-assigned U.S.
Pat. Nos. 6026820; 5988176; 5915387; 5692526; 5692525;
5666976; and 5499636. The carbon-coated molecular sieve sorbent
is preferably incorporated into a filter portion.
[0029] In a preferred embodiment, the internal cavities of the
molecular sieve will be larger than certain selected constituents
of mainstream smoke. Because only those molecules that are small
enough to pass through the pores of the molecular sieve materials
can enter the cavities and be sorbed on the interior surface, smaller
constituents of mainstream smoke can be selectively sorbed. In yet
another preferred embodiment, activated carbon within the interior
pores of the molecular sieve is protected from loss of activity
due to adsorption of larger smoke constituents because such larger
molecules cannot enter the pores due to their size. Moreover, the
thickness of the carbon coating in the interior passages of the
molecular sieves may be adjusted to modify the pore size distribution,
and may thus be used to further enhance and refine the size selectivity.
[0030] The term "mesoporous molecular sieve" as used
herein refers to a porous structure composed of an inorganic material
having an average pore size of 20 to 500 .ANG., preferably 20 to
300 .ANG.. Such mesoporous molecular sieves include natural or synthetic
aluminosilicates, silicates, aluminophosphates, and other mesoporous
materials which may optionally further comprise inorganic or organic
ions and/or metals.
[0031] Examples of mesoporous molecular sieve materials are described,
for example, in technical literature and patents relating to MCM-41
and MCM-45 and SBA-15; such as U.S. Pat. Nos. 5098684 5102643
and 5108725 hereby incorporated by reference in their entirety.
[0032] The term "sorption" denotes filtration through
absorption and/or adsorption. Sorption is intended to cover interactions
on the outer surface of the carbon-modified sorbent, as well as
interactions within the pores, such as channels or cavities, of
the sorbent. In other words, a sorbent is a substance that has the
ability to condense or hold molecules of other substances on its
surface and/or the ability to take up another substance, i.e. through
penetration of the other substance into its inner structure or into
its pores. The term adsorption also denotes filtration through physical
sieving, i.e. capture of certain constituents in the pores of the
carbon-modified sorbent. The term "sorbent" as used herein
refers to either an adsorbent, an absorbent, or a substance that
functions as both an adsorbent and an absorbent.
[0033] The sorbent material may be made by impregnating the inorganic
substrate with any suitable carbon source or carbon precursor. Any
suitable method for making a carbon-coated porous inorganic substrate
may be used, such as the methods disclosed in U.S. Pat. Nos. 5451444
and 6156697 which are both hereby incorporated by reference in
their entirety. The carbon-coated molecular sieve sorbent may comprise
both an internal and an exterior coating.
[0034] Solutions, mixtures, or essentially pure carbon source liquids
may be used. Sugar solutions may be used to impregnate a porous
inorganic substrate, and the sugar in solution may be dried at moderate
to high temperatures prior to carbonization. Preferably, the carbon
sources are liquid at ambient temperatures or can be liquified with
heating. Preferred carbon sources will have low cost, low viscosity,
high cross-linking upon curing, and high carbon content. Examples
of carbon sources include thermoplastic resins, thermoset resins,
sugar solutions, furfuryl alcohol, and tar or tar pitch. Low viscosity
resins, preferably thermosetting resins, such as phenolic resins,
are particularly preferred. Activated carbon powder may be added
to the carbon source liquid to increase the activity of the coating.
A catalyst may be added to the carbon source fluid to aid the carbonization
reaction; e.g. concentrated sulphuric acid and concentrated phosphoric
acid can be used as catalysts for the carbonization reaction.
[0035] The carbon source fluid may be impregnated within and/or
coated on the substrate by any method including dipping, soaking,
spraying, or like methods. The coated substrate can then be treated
to solidify the carbon precursor such as by drying or curing through
heat, catalytic, or chemical processes. Typically, the material
is heated to effect the drying or curing for a time sufficient to
substantially complete the process such as heating up to 1000 to
200.degree. C. or higher for about 0.5 to 5 hours or longer or shorter.
The curing is typically performed at atmospheric pressure in air
but can be performed at reduced pressure and/or in an inert or oxygen
free atmosphere. The material is then heated at temperatures sufficient
to substantially convert the carbon source or precursor to carbon.
The conversion or carbonization is typically accomplished by heating
the material to a temperature of 600.degree. to 1000.degree. C.
for about 1 to 10 hours, more or less, in a reducing or inert atmosphere.
The carbon may be further preferably activated by any method known
for activating carbon such as for example by exposure to steam at
high temperature such as 600.degree. to 1000.degree. C.
[0036] The pore size of the carbon-coated molecular sieve sorbent
may be modified or adjusted in the manufacturing process. For example,
if constituents of the smoke stream of about 5-6 .ANG. are to be
removed, a substrate having a pore size of greater than about 20
.ANG. may be chosen. Coating as described above may result in changing
the mesoporous molecular sieve pore size to a microporous average
pore size of about 10 .ANG. to optimize selectivity. The carbon-coated
molecular sieve sorbent can be modified to obtain a desired pore
size by selectively combining the properties of the substrate and
the carbon source precursor. In preferred embodiments, a carbon-coated
molecular sieve sorbent may be designed to remove, for example,
13-butadiene, acrolein, and/or other aldehydes by creating a carbon-coated
molecular sieve sorbent having average pore diameters that are larger
than such selected constituents and smaller than the diameter of
a tobacco smoke constituent such as a flavor constituent. In a preferred
embodiment, the average pore size of the carbon coated molecular
sieve sorbent is less than about 100 .ANG., and more preferably
less than about 20 .ANG..
[0037] In a preferred embodiment, a carbon-coated molecular sieve
sorbent as described above is incorporated into or onto a support
such as lightly or tightly folded paper inserted into a hollow portion
of the cigarette filter. The support is preferably in the form of
a sheet material such as crepe paper, filter paper, or tipping paper.
However, other suitable support materials such as organic or inorganic
cigarette compatible materials can also be used.
[0038] The carbon-coated molecular sieve sorbent may be located
in a filter portion. Preferably, about 10 mg to about 300 mg of
the carbon-coated molecular sieve sorbent will be used in the filter.
For example, amounts such as at least about 20 30 50 75 100
150 200 or 250 mg of the carbon-coated molecular sieve sorbent
can be used in the filter.
[0039] Any conventional or modified filter design may be used,
which comprises the carbon-coated molecular sieve sorbent capable
of selectively sorbing at least one selected constituent of mainstream
smoke. Examples of filter designs include, but are not limited to
a mono filter, a dual filter, a triple filter, a cavity filter,
a recessed filter or a free-flow filter. Mono filters typically
contain a variety of cellulose acetate tow or cellulose paper materials.
Pure mono cellulose filters or paper filters offer good tar and
nicotine retention, and are highly degradable. The carbon-coated
molecular sieve sorbent may be incorporated into the cellulose filters
or paper filters. Dual filters usually comprise a cellulose acetate
mouth side and a pure cellulose segment or cellulose acetate segment,
with carbon-coated molecular sieve sorbent on the smoking material
or tobacco side. The length and pressure drop of the two segments
of the dual filter can be adjusted to provide optimal adsorption,
while maintaining acceptable draw resistance. Triple filters may
have mouth and smoking material or tobacco side segments, while
the middle segment comprises a material or paper containing the
carbon-coated molecular sieve sorbent. Cavity filters have two segments,
e.g., acetate-acetate, acetate-paper or paper-paper, separated by
a cavity containing the carbon-coated molecular sieve sorbent. Recessed
filters have an open cavity on the mouth side, and typically incorporate
the carbon-coated molecular sieve sorbent into the plug material.
The filters may also optionally be ventilated, and/or comprise additional
sorbents (such as charcoal or magnesium silicate), catalysts, flavorants
or other additives used in the cigarette filter art.
[0040] FIG. 1 illustrates a cigarette 2 having a tobacco rod 4
a filter portion 6 and a mouthpiece filter plug 8. As shown, carbon-coated
molecular sieve sorbent can be loaded (e.g., coated) onto folded
paper 10 inserted into a hollow cavity such as the interior of a
free-flow sleeve 12 forming part of the filter portion 6.
[0041] FIG. 2 shows a cigarette 2 having a tobacco rod 4 and a
filter portion 6 wherein the folded paper 10 is located in the
hollow cavity of a first free-flow sleeve 13 located between the
mouthpiece filter 8 and a second free-flow sleeve 15. The paper
10 can be used in forms other than as a folded sheet. For instance,
the paper 10 can be deployed as one or more individual strips, a
wound roll, etc. In whichever form, a desired amount of carbon-coated
molecular sieve sorbent can be provided in the cigarette filter
portion by a combination of the amount of the sorbent and/or the
total area of sorbent coated paper employed in the filter (e.g.,
higher amounts of carbon-coated molecular sieve sorbent can be provided
simply by using larger pieces of sorbent coated paper). In the cigarettes
shown in FIGS. 1 and 2 the tobacco rod 4 and the filter portion
6 are joined together with tipping paper 14. In both cigarettes,
the filter portion 6 may be held together by filter overwrap 11.
[0042] Carbon-coated molecular sieve sorbent can be incorporated
into the filter paper in a number of ways. For example, a carbon-coated
molecular sieve sorbent can be mixed with water to form a slurry.
The slurry can then be coated onto pre-formed filter paper and allowed
to dry. The filter paper can then be incorporated into the filter
portion of a cigarette in the manner shown in FIGS. 1 and 2. Alternatively,
the dried paper can be wrapped into a plug shape and inserted into
a filter portion of the cigarette. For example, the paper can be
wrapped into a plug shape and inserted as a plug into the interior
of a free-flow filter element such as a polypropylene or cellulose
acetate sleeve. In another arrangement, the paper can comprise an
inner liner of such a free-flow filter element.
[0043] Alternatively and preferably, carbon-coated molecular sieve
sorbent is added to the filter paper during the paper-making process.
For example, carbon-coated molecular sieve sorbent can be mixed
with bulk cellulose to form a cellulose pulp mixture. The mixture
can be then formed into filter paper according to any conventional
or modified methods.
[0044] In another preferred embodiment, the carbon-coated molecular
sieve sorbent is incorporated into the fibrous material of the cigarette
filter portion itself. Such filter materials include, but are not
limited to, fibrous filter materials including paper, cellulose
acetate fibers, and polypropylene fibers. This embodiment is illustrated
in FIG. 3 which shows a cigarette 2 comprised of a tobacco rod
4 and a filter portion 6 in the form of a plug-space-plug filter
having a mouthpiece filter 8 a plug 16 and a space 18. The plug
16 can comprise a tube or solid piece of material such as polypropylene
or cellulose acetate fibers. The tobacco rod 4 and the filter portion
6 are joined together with tipping paper 14. The filter portion
6 may include a filter overwrap 11. The filter overwrap 11 containing
traditional fibrous filter material and carbon-coated molecular
sieve sorbent can be incorporated in or on the filter overwrap 11
such as by being coated thereon. Alternatively, carbon-coated molecular
sieve sorbent can be incorporated in the mouthpiece filter 8 in
the plug 16 and/or in the space 18. Moreover, carbon-coated molecular
sieve sorbent can be incorporated in any element of the filter portion
of a cigarette. For example, the filter portion may consist only
of the mouthpiece filter 8 and carbon-coated molecular sieve sorbent
can be incorporated in the mouthpiece filter 8 and/or in the tipping
paper 14.
[0045] FIG. 4 shows a cigarette 2 comprised of a tobacco rod 4
and filter portion 6. This arrangement is similar to that of FIG.
3 except the space 18 is filled with granules of carbon-coated molecular
sieve sorbent or a plug 15 made of material such as fibrous polypropylene
or cellulose acetate containing carbon-coated molecular sieve sorbent.
As in the previous embodiment, the plug 16 can be hollow or solid
and the tobacco rod 4 and filter portion 6 are joined together with
tipping paper 14. There is also a filter overwrap 11.
[0046] FIG. 5 shows a cigarette 2 comprised of a tobacco rod 4
and a filter portion 6 wherein the filter portion 6 includes a mouthpiece
filter 8 a filter overwrap 11 tipping paper 14 to join the tobacco
rod 4 and filter portion 6 a space 18 a plug 16 and a hollow
sleeve 20. Carbon-coated molecular sieve sorbent can be incorporated
into one or more elements of the filter portion 6. For instance,
carbon-coated molecular sieve sorbent can be incorporated into the
sleeve 20 or granules of carbon-coated molecular sieve sorbent can
be filled into the space within the sleeve 20. If desired, the plug
16 and sleeve 20 can be made of material such as fibrous polypropylene
or cellulose acetate containing carbon-coated molecular sieve sorbent.
As in the previous embodiment, the plug 16 can be hollow or solid.
[0047] FIGS. 6 and 7 show further modifications of the filter portion
6. In FIG. 6 cigarette 2 is comprised of a tobacco rod 4 and filter
portion 6. The filter portion 6 includes a mouthpiece filter 8
a filter overwrap 11 a plug 22 and a sleeve 20 and carbon-coated
molecular sieve sorbent can be incorporated in one or more of these
filter elements. In FIG. 7 the filter portion 6 includes a mouthpiece
filter 8 and a plug 24 and carbon-coated molecular sieve sorbent
can be incorporated in one or more of these filter elements. Like
the plug 16 the plugs 22 and 24 can be solid or hollow. In the
cigarettes shown in FIGS. 6 and 7 the tobacco rod 4 and filter
portion 6 are joined together by tipping paper 14.
[0048] Various techniques can be used to apply carbon-coated molecular
sieve sorbent to filter fibers or other substrate supports. For
example, carbon-coated molecular sieve sorbent can be added to the
filter fibers before they are formed into a filter cartridge, e.g.,
a tip for a cigarette. Carbon-coated molecular sieve sorbent can
be added to the filter fibers, for example, in the form of a dry
powder or a slurry. If carbon-coated molecular sieve sorbent is
applied in the form of a slurry, the fibers are preferably allowed
to dry before they are formed into a filter cartridge.
[0049] In another preferred embodiment, carbon-coated molecular
sieve sorbent is employed in a hollow portion of a cigarette filter.
For example, some cigarette filters have a plug/space/plug configuration
in which the plugs comprise a fibrous filter material and the space
is simply a void between the two filter plugs. That void can be
filled with the carbon-coated molecular sieve sorbent. An example
of this embodiment is shown in FIG. 3. Carbon-coated molecular sieve
sorbent can be in granular form or can be loaded onto a suitable
support such as a fiber or thread.
[0050] In another embodiment, the carbon-coated molecular sieve
sorbent is employed in a filter portion of a cigarette for use with
a smoking device as described in U.S. Pat. No. 5692525 the entire
content of which is hereby incorporated by reference. FIG. 8 illustrates
one type of construction of a cigarette 100 which can be used with
an electrical smoking device. As shown, the cigarette 100 includes
a tobacco rod 60 and a filter portion 62 joined by tipping paper
64. The filter portion 62 preferably contains a tubular free-flow
filter element 102 and a mouthpiece filter plug 104. The free-flow
filter element 102 and mouthpiece filter plug 104 may be joined
together as a combined plug 110 with plug wrap 112. The tobacco
rod 60 can have various forms incorporating one or more of the following
items: an overwrap 71 another tubular free-flow filter element
74 a cylindrical tobacco plug 80 preferably wrapped in a plug wrap
84 a tobacco web 66 comprising a base web 68 and tobacco flavor
material 70 and a void space 91. The free-flow filter element 74
provides structural definition and support at the tipped end 72
of the tobacco rod 60. At the free end 78 of the tobacco rod 60
the tobacco web 66 together with overwrap 71 are wrapped about cylindrical
tobacco plug 80. Various modifications can be made to a filter arrangement
for such a cigarette incorporating the carbon-coated molecular sieve
sorbent.
[0051] In such a cigarette, carbon-coated molecular sieve sorbent
can be incorporated in various ways such as by being loaded onto
paper or other substrate material which is fitted into the passageway
of the tubular free-flow filter element 102 therein. It may also
be deployed as a liner or a plug in the interior of the tubular
free-flow filter element 102. Alternatively, carbon-coated molecular
sieve sorbent can be incorporated into the fibrous wall portions
of the tubular free-flow filter element 102 itself. For instance,
the tubular free-flow filter element or sleeve 102 can be made of
suitable materials such as polypropylene or cellulose acetate fibers
and carbon-coated molecular sieve sorbent can be mixed with such
fibers prior to or as part of the sleeve forming process.
[0052] In another embodiment, carbon-coated molecular sieve sorbent
can be incorporated into the mouthpiece filter plug 104 instead
of in the element 102. However, as in the previously described embodiments,
carbon-coated molecular sieve sorbent may be incorporated into more
than one constituent of a filter portion such as by being incorporated
into the mouthpiece filter plug 104 and into the tubular free-flow
filter element 102. The filter portion 62 of FIG. 8 can also be
modified to create a void space into which carbon-coated molecular
sieve sorbent can be inserted.
[0053] As explained above, carbon-coated molecular sieve sorbent
can be incorporated in various support materials. When carbon-coated
molecular sieve sorbent is used in filter paper, the particles may
have an average particle size of up to 100 .mu.m, preferably 2 to
50 .mu.m. When carbon-coated molecular sieve sorbent is used in
granular form, larger particles may be used. Such particles preferably
have a mesh size from 20 to 60 and more preferably from 35 to 60
mesh.
[0054] The amount of carbon-coated molecular sieve sorbent employed
in the cigarette filter by way of incorporation on a suitable support
such as filter paper and/or filter fibers depends on the amount
of constituents in the tobacco smoke and the amount of constituents
desired to be removed. As an example, the filter paper and the filter
fibers may contain from 10% to 50% by weight of carbon-coated molecular
sieve sorbent.
[0055] One embodiment relates to methods of making a filter. The
methods involve incorporating a carbon-coated molecular sieve sorbent
into a cigarette filter, wherein the carbon-coated molecular sieve
sorbent is capable of sorbing at least one selected constituent
from mainstream smoke. Any conventional or modified method of making
cigarette filters may be used to incorporate the carbon-coated molecular
sieve sorbent.
[0056] Another embodiment relates to methods for making cigarettes.
In one embodiment, the method comprises: (i) providing a cut filler
to a cigarette making machine to form a tobacco column; (ii) placing
a paper wrapper around the tobacco column to form a tobacco rod;
and (iii) attaching the cigarette filter as described above to the
tobacco rod to form the cigarette.
[0057] Examples of suitable types of tobacco materials which may
be used 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. Tobacco substitutes may also
be used.
[0058] 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 {fraction (1/10)} inch to about
{fraction (1/20)} inch or even {fraction (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 conventional or modified additives (e.g., burn additives,
combustion modifying agents, coloring agents, binders, etc.).
[0059] Cigarettes can be manufactured to any desired specification
using standard or modified cigarette making techniques and equipment.
The 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 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.
[0060] Yet another embodiment relates to methods of smoking the
cigarette described above, which involve lighting the cigarette
to form smoke and drawing the smoke through the cigarette, wherein
during the smoking of the cigarette, the carbon-coated molecular
sieve sorbent is capable of selectively sorbing one or more selected
constituents from mainstream smoke. Preferably at least 10%, 20%,
30%, 40%, 50% or more of the selected constituent is removed from
the tobacco smoke by the sorbent.
[0061] "Smoking" of a cigarette means the heating or
combustion of the cigarette to form smoke. Generally, smoking of
a cigarette involves lighting one end of the cigarette and drawing
the cigarette smoke through the mouth end of the cigarette, while
the tobacco contained therein undergoes a combustion reaction. However,
the cigarette may also be smoked by other means. For example, the
cigarette may be smoked by heating the cigarette and/or heating
using an electrical heater, as described in commonly-assigned U.S.
Pat. Nos. 6026820; 5988176; 5915387; 5692526; 5692525;
5666976; and 5499636 for example.
EXAMPLE 1
[0062] Sucrose is used as a carbon source and loaded into a mesoporous
SBA-15 molecular sieve silicate substrate via incipient-wetness
impregnation in water. One gram of mesoporous SBA-15 molecular sieve
silicate, with a uniform pore size of about 67 .ANG. (FIG. 9), is
added to 10 milliliters of an aqueous solution containing 1.25 grams
of sucrose, and 0.14 grams of concentrated sulfuric acid (used as
a catalyst for carbonization). The mixture is slurried and dried
at 100.degree. C. for about 12 hours, then heated at 160.degree.
C. for about 12 hours yielding a yellowish composite material. The
composite material is carbonized at 843.degree. C. under a 0.5 liter/minute
flow of nitrogen for about 1 hour, followed by activation at 950.degree.
C. under a 0.5 liter/minute flow of carbon dioxide for about 0.5
hours, yielding a carbon-coated mesoporous SBA-15 molecular sieve
silicate (Sample 1).
[0063] The carbon loading is controlled by the concentration of
sucrose used in the aqueous solution for impregnation. Pore structure
analysis of Sample 1 (FIG. 10) shows uniform pores of about 37 .ANG.
(about half that of the parent SBA-15 silicate substrate, FIG. 9).
The microporosity of Sample 1 is expected to be higher than the
parent SBA-15 silicate substrate due to the carbon coating. FIG.
11 further illustrates the effect of sucrose concentration on the
carbon loading and effective pore size.
[0064] Sample 1 is crushed and sieved to a mesh size of 20 to 50
(0.85 to 0.30 millimeters) and loaded into a 2.5 millimeter space
(0.126 cm.sup.3) of a plug-space-plug filter configuration using
industry reference 1R4F cigarettes. Cigarettes are smoked under
FTC conditions (2 second, 35 cm.sup.3 puff every 60 seconds) and
the fourth puff is analyzed using gas chromatography/mass spectrometer
(GC/MS). Ethane is used as an internal standard and the percent
reduction of various gas phase smoke constituents is calculated
versus an unmodified 1R4F cigarette. The results shown in Table
1 are the average of two cigarettes.
EXAMPLE 2
[0065] Phenolic resin is used as a carbon source and loaded into
a mesoporous SBA-15 molecular sieve silicate substrate via incipient-wetness
impregnation in ethanol. To 1 gram of the mesoporous SBA-15 molecular
sieve silicate are added 10 milliliters of an ethanolic solution
containing 2 grams of a phenolic resin (average molecular weight
900), and 0.04 grams of concentrated phosphoric acid (used as a
catalyst for carbonization). The mixture is slurried and dried at
100.degree. C. for about 12 hours, then heated at 160.degree. C.
for about 12 hours yielding a dark composite material. The composite
material is carbonized at 843.degree. C. under a 0.5 liter/minute
flow of nitrogen for about 1 hour, followed by activation at 950.degree.
C. under a 0.5 liter/minute flow of carbon dioxide for about 0.5
hours, yielding a carbon-coated mesoporous SBA-15 molecular sieve
silicate (Sample 2).
[0066] In this preparation, the desired carbon loading is controlled
by the concentration of the phenolic resin used in the ethanolic
solution for impregnation. Sample 2 is crushed and sieved to a mesh
size of 20 to 50 (0.85 to 0.30 millimeters) and loaded into a 2.5
millimeter space (0.126 cm.sup.3) of a plug-space-plug filter configuration
using industry reference 1R4F cigarettes. Cigarettes are smoked
under FTC conditions (2 second 35 cm.sup.3 puff every 60 seconds)
and the fourth puff is analyzed using gas chromatography/mass spectrometer
(GC/MS). Ethane is used as an internal standard and the percent
reduction for various gas phase smoke constituents are calculated
versus an unmodified 1R4F cigarette. The results shown in Table
1 are the average of two cigarettes.
EXAMPLE 3
[0067] Resorcinol and formaldehyde are used as the carbon source
and loaded into a mesoporous SBA-15 molecular sieve silicate substrate
via incipient-wetness impregnation in water. To 1 gram of the mesoporous
SBA-15 molecular sieve silicate are added 10 milliliters of an aqueous
solution containing 2.2 grams of resorcinol, 1.2 grams of formaldehyde,
and 0.03 grams of sodium carbonate (used as a catalyst for carbonization).
The mixture is slurried and dried at 100.degree. C. for about 12
hours, then heated at 160.degree. C. for about 12 hours yielding
a reddish composite material. The composite material is carbonized
at 843.degree. C. under a 0.5 liter/minute flow of nitrogen for
about 1 hour, followed by activation at 950.degree. C. under a 0.5
liter/minute flow of carbon dioxide for about 0.5 hours, yielding
a carbon coated mesoporous SBA-15 molecular sieve silicate (Sample
3).
[0068] In this preparation, the carbon loading is controlled by
the concentration of resorcinol and formaldehyde used in the aqueous
solution for impregnation. Sample 3 is crushed and sieved to a mesh
size of 20 to 50 (0.85 to 0.30 millimeters), and loaded into a 2.5
millimeter space (0.126 cm.sup.3) of a plug-space-plug filter configuration
using industry reference 1R4F cigarettes. Cigarettes are smoked
under FTC conditions (2 second 35 cm.sup.3 puff every 60 seconds)
and the fourth puff is analyzed using gas chromatography/mass spectrometer
(GC/MS). Ethane is used as an internal standard and the percent
reduction for various gas phase smoke constituents is calculated
versus an unmodified 1R4F cigarette. The results shown in Table
1 are the average of two cigarettes.
1TABLE 1 Percent Reduction versus 1R4F (0.126 cc space in filter
filled with granular material 20-50 mesh) Methyl ethyl Sample Acetone
Acrolein Acrylonitrile Benzene Hexane Isobutyraldehyde Isoprene
ketone Toluene Sample 1 55 55 31 55 45 50 27 66 69 Sample 2 54 54
32 59 50 53 32 68 71 Sample 3 50 64 36 77 70 61 31 82 90
[0069] All of the above-mentioned references are herein incorporated
by reference in their entirety to the same extent as if each individual
reference was specifically and individually indicated to be incorporated
herein by reference in its entirety.
[0070] The foregoing Examples serve to further illustrate various
aspects of the invention. The Examples are not meant to and should
not be construed to limit the invention in any way. Furthermore,
while the invention has been described in detail with reference
to embodiments thereof, it will be apparent to one skilled in the
art that various changes can be made, and equivalents employed,
without departing from the scope of the invention. |