U.S. patent application number 10/838872 was filed with the patent office on 2005-01-06 for method and compositions for imparting cooling effect to tobacco products.
Invention is credited to Bereman, Robert D., Shi, Xuling.
Application Number | 20050000529 10/838872 |
Document ID | / |
Family ID | 23344803 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000529 |
Kind Code |
A1 |
Bereman, Robert D. ; et
al. |
January 6, 2005 |
Method and compositions for imparting cooling effect to tobacco
products
Abstract
The present invention relates to smoking articles such as
cigarettes, and in particular to a method and composition for
providing a cooling effect to cigarettes. The tobacco rod of the
cigarette contains a compound that imparts a cooing effect and
sensation of freshness to tobacco smoke.
Inventors: |
Bereman, Robert D.; (Apex,
NC) ; Shi, Xuling; (Raleigh, NC) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
23344803 |
Appl. No.: |
10/838872 |
Filed: |
May 3, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10838872 |
May 3, 2004 |
|
|
|
PCT/US02/40835 |
Dec 18, 2002 |
|
|
|
60343122 |
Dec 19, 2001 |
|
|
|
Current U.S.
Class: |
131/334 ;
131/360; 131/364 |
Current CPC
Class: |
A24B 15/34 20130101;
A24B 15/406 20130101; A24B 15/301 20130101 |
Class at
Publication: |
131/334 ;
131/364; 131/360 |
International
Class: |
A24B 015/30 |
Claims
What is claimed is:
1. A smoking article, the smoking article comprising: a smokable
material; and a compound comprising a cyclic .alpha.-keto enamine,
wherein the cyclic .alpha.-keto enamine is capable of imparting a
cooling sensation to an oral cavity of a smoker upon inhalation of
a smoke stream from the smoking article.
2. The smoking article of claim 1, wherein the smokable material
comprises a tobacco.
3. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine is deposited on the smokable material.
4. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine is selected from the group consisting of
3-methyl-2-(1-piperidinyl)-2-cyc- lopenten-1-one,
3-methyl-2-diethylamino-2-cyclopenten-1-one,
5-methyl-2-(1-piperidinyl)-2-cyclopenten-1-one,
5-methyl-2-diethylamino-2- -cyclopenten-1-one,
5-methyl-2-dibutylamino-2-cyclopenten-1-one,
5-methyl-2-dihexylamino-2-cyclopenten-1-one,
5-ethyl-2-(1-pyrrolidinyl)-2- -cyclopenten-1-one,
(E)-4,5-dimethyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-on- e,
3,5-dimethyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one,
3,4-dimethyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one,
3-(1-pyrrolidinyl)-2-cyclopenten-1-one,
2-methyl-3-(1-pyrrolidinyl)-2-cyc- lopenten-1-one,
1-pyrrolidinyl)-2-cyclohexen-1-one,
3-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one,
3,5,5-trimethyl-2-(1-pyrr- olidinyl)-2-cyclohexen-1-one,
6-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-o- ne,
4,4,6-trimethyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one,
5-methyl-2-(1-morpholino)-2-cyclopenten-1-one,
(S)-5-methyl-2-(2-methoxyc-
arbony1-1-pyrrolidinyl)-2-cyclopenten-1-one,
(S)-3-methyl-2-(2-carboxy-1-p- yrrolidinyl)-2-cyclopenten-1-one,
2,5-dimethyl-4-(1-pyrrolidinyl)-3-(2H)-f- uranone,
4,5-dimethyl-3-(1-pyrrolidinyl)-2-(5H)-furanone, and mixtures
thereof.
5. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine comprises
3-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one.
6. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine comprises
5-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one.
7. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine comprises 5-methyl-4-(1-pyrrolidinyl)-3-(2H)-furanone.
8. The smoking article of claim 1, wherein the cyclic .alpha.-keto
enamine comprises 4-methyl-3-(1-pyrrolidinyl)-2-(5H)-furanone.
9. The smoking article of claim 1, comprising a cigarette.
10. The smoking article of claim 1, further comprising a
filter.
11. The smoking article of claim 10, wherein the filter comprises
an activated charcoal or an activated carbon.
12. A method of providing a smoke stream from a cigarette, wherein
the smoke stream is capable of imparting a cooling sensation to an
oral cavity, the method comprising: providing a cigarette, the
cigarette comprising a tobacco charge and a compound comprising a
cyclic .alpha.-keto enamine; combusting the tobacco charge, whereby
a smoke stream is produced, the smoke stream comprising the cyclic
.alpha.-keto enamine; and inhaling the smoke stream, whereby a
cooling sensation is imparted to an oral cavity.
13. A smoking article, the smoking article comprising: a smokable
material; and a compound selected from the group consisting of a
carboxamide, a mentane glycerol ketal, a menthyl ester, an
alkyl-substituted urea, a sulfonamide, a phosphine oxide, wherein
the compound is capable of imparting a cooling sensation to an oral
cavity of a smoker upon inhalation of a smoke stream from the
smoking article.
14. The smoking article of claim 13, wherein the carboxamide has a
chemical formula corresponding to: 10
15. The smoking article of claim 13, wherein the mentane glycerol
ketal has a chemical formula corresponding to: 11
16. The smoking article of claim 13, wherein the menthyl ester has
a chemical formula corresponding to: 12
17. The smoking article of claim 13, wherein the alkyl-substituted
urea has a chemical formula corresponding to: 13
18. The smoking article of claim 13, wherein the sulfonamide has a
chemical formula corresponding to: 14
19. The smoking article of claim 13, wherein the phosphine oxide
has a chemical formula corresponding to: 15
20. The smoking article of claim 13, wherein the smoking material
comprises a tobacco.
Description
RELATED APPLICATIONS
[0001] This application is a continuation, under 35 U.S.C. .sctn.
120, of International Patent Application No. PCTUS02/40835, filed
on Dec. 18, 2002 under the Patent Cooperation Treaty (PCT), which
was published by the International Bureau in English on Jul. 3,
2003, which designates the United States and which claims the
benefit of U.S. Provisional Patent Application No. 60/343,122,
filed Dec. 19, 2001.
FIELD OF THE INVENTION
[0002] The present invention relates to smoking articles such as
cigarettes, and in particular to a method and composition for
providing a cooling effect to cigarettes. The tobacco rod of the
cigarette contains a compound that imparts a cooing effect and
sensation of freshness to tobacco smoke.
BACKGROUND OF THE INVENTION
[0003] Menthol, or 2-isopropyl-5-methyl-cyclohexanol, is a cyclic
monoterpene. It is a major constituent of peppermint oil, which has
a minty taste and odor and which produces a cooling sensation when
inhaled or consumed. Menthol is used as a flavorant in a variety of
products, including toothpastes, mouthwashes, oral sprays, drugs,
cough drops, cough lozenges, analgesic balms, inhalers, chewing
gums, hard candies, chocolates, beverages, liquors, lotions,
after-shave lotions, shampoos, moist towelettes, perfumes,
deodorants, and the like.
[0004] Menthol is also a popular flavorant for use in cigarettes,
pipe tobacco, chewing tobacco, and other smoking materials. It is
used extensively because of the refreshing cooling effect it
imparts to tobacco smoke. Menthol, however, has a number of
potential drawbacks associated with its use as a flavorant for
smoking materials. Menthol has a minty flavor that may not appeal
to all tobacco users. The cooling effect exhibited by menthol may
be insufficient for certain applications. Menthol also possesses a
high degree of volatility at room temperature. This volatility
makes it difficult to control the concentration of menthol in
cigarettes and can result in problems in packaging and handling.
Smoking products containing menthol may also have a short shelf
life due to loss of menthol from the product during storage. This
problem is especially acute for menthol-flavored cigarettes that
also incorporate a charcoal filter. Menthol is irreversibly bound
to charcoal and other adsorbents commonly used in filter
cigarettes, and over time a substantial and unacceptable decrease
in the available menthol results. Adsorption of menthol may also
adversely affect the performance of the cigarette filter in
removing undesirable components from the smoke generated during
combustion of the tobacco product.
[0005] Accordingly, considerable time and expense has been spent on
development of a satisfactory method for producing cigarettes
exhibiting a satisfactory level of cooling effect. Methods for
mentholating unfiltered cigarettes and filtered cigarettes not
incorporating an adsorbent are generally unsatisfactory for use on
charcoal-filtered cigarettes. For example, the classic method of
mentholation using mentholated strips sealed in a cigarette pack is
unsatisfactory because the charcoal will simply absorb the menthol
during storage, resulting in what is essentially a non-mentholated
cigarette.
[0006] Other methods for producing mentholated smoking products
that have been investigated include providing menthol adsorbed on a
support, for example, diatomaceous earth, from which the menthol is
later released. Such methods suffer from low menthol yields, and
may result in unacceptable taste or appearance of the smoking
product.
[0007] Other methods have focused on the preparation of menthol
derivatives or similar compounds that release menthol or
menthol-like flavorants upon pyrolysis or hydrolysis. Such
derivatives include ester and carbonate derivatives of menthol, for
example, the derivatives disclosed in U.S. Pat. Nos. 3,312,226,
3,332,428, 3,419,543, 4,119,106, 4,092,988, 4,171,702, 4,177,339,
4,212,310, 4,532,944 and 4,578,486. However, such derivatives may
suffer from one or more drawbacks. For example, they may have a
degree of volatility that makes them unsuited for use with
adsorbents, they may not yield a sufficient quantity of free
menthol upon decomposition, the may exhibit only a minimal cooling
effect, they may be unstable or difficult to process, or the
pyrolysis or hydrolysis products may be toxic, carcinogenic, or may
result in an unacceptable taste.
SUMMARY OF THE INVENTION
[0008] While various methods have been provided for imparting a
cooling effect to cigarettes, no satisfactory and practical
substitutes for menthol have heretofore been available. There is,
therefore, a need for compounds that are capable of delivering an
acceptable feeling of freshness and coolness to the smoke stream of
a cigarette.
[0009] Accordingly, in a first embodiment a smoking article is
provided, the smoking article including a smokable material and a
compound including a cyclic .alpha.-keto enamine, wherein the
compound is capable of imparting a cooling sensation to an oral
cavity of a smoker upon inhalation of a smoke stream from the
smoking article.
[0010] In an aspect of the first embodiment, the compound is
deposited on the smokable material.
[0011] In an aspect of the first embodiment, the cyclic
.alpha.-keto enamine is selected from the group consisting of
3-methyl-2-(1-piperidiny- l)-2-cyclopenten-1-one,
3-methyl-2-diethylamino-2-cyclopenten-1-one,
5-methyl-2-(1-piperidinyl)-2-cyclopenten-1-one,
5-methyl-2-diethylamino-2- -cyclopenten-1-one,
5-methyl-2-dibutylamino-2-cyclopenten-1-one,
5-methyl-2-dihexylamino-2-cyclopenten-1-one,
5-ethyl-2-(1-pyrrolidinyl)-2-
-cyclopenten-1-pyrrolidinyl)-2-cyclopenten-1-one,
3,4-dimethyl-2-(1-pyrrol- idinyl)-2-cyclopenten-1-one,
3-(1-pyrrolidinyl)-2-cyclopenten-1-one,
2-methyl-3-(1-pyrrolidinyl)-2-cyclopenten-1-one,
2-(1-pyrrolidinyl)-2-cyc- lohexen-1-one,
3-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one,
3,5,5-trimethyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one,
6-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one,
4,4,6-trimethyl-2-(1-pyrr- olidinyl)-2-cyclohexen-1-one,
5-methyl-2-(1-morpholino)-2-cyclopenten-1-on- e,
(S)-5-methyl-2-(2-methoxycarbony1-1-pyrrolidinyl)-2-cyclopenten-1-one,
(S)-3-methyl-2-(2-carboxy-1-pyrrolidinyl)-2-cyclopenten-1-one,
2,5-dimethyl-4-(1-pyrrolidinyl)-3-(2H)-furanone,
4,5-dimethyl-3-(1-pyrrol- idinyl)-2-(5H)-furanone, and mixtures
thereof.
[0012] In an aspect of the first embodiment, the cyclic
.alpha.-keto enamine comprises
3-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one, or
5-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one, or
5-methyl-4-(1-pyrrolidinyl)-3-(2H)-furanone, or
4-methyl-3-(1-pyrrolidiny- l)-2-(5H)-furanone.
[0013] In an aspect of the first embodiment, the smoking article is
a cigarette.
[0014] In an aspect of the first embodiment, the smoking material
further includes a filter, and the filter can include charcoal.
[0015] In a second embodiment, a method of providing a smoke stream
from a cigarette is provided, wherein the smoke stream is capable
of imparting a cooling sensation to the oral cavity, the method
comprising the steps of providing a cigarette, the cigarette
including a tobacco charge and a compound including a cyclic
.alpha.-keto enamine; combusting the tobacco charge, whereby a
smoke stream is produced; and inhaling the smoke stream from the
cigarette, whereby a cooling sensation is imparted to an oral
cavity.
[0016] In a third embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a carboxamide, wherein the carboxamide is capable of
imparting a cooling sensation to an oral cavity of a smoker upon
inhalation of a smoke stream from the smoking article, the smoke
stream comprising the carboxamide. The carboxamide can have a
chemical formula corresponding to: 1
[0017] In a fourth embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a mentane glycerol ketal, wherein the mentane glycerol
ketal is capable of imparting a cooling sensation to an oral cavity
of a smoker upon inhalation of a smoke stream from the smoking
article, the smoke stream including the mentane glycerol ketal. The
mentane glycerol ketal can have a chemical formula corresponding
to: 2
[0018] In a fifth embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a menthyl ester, wherein the menthyl ester is capable of
imparting a cooling sensation to an oral cavity of a smoker upon
inhalation of a smoke stream from the smoking article, the smoke
stream including the menthyl ester. The menthyl ester can have a
chemical formula corresponding to: 3
[0019] In a sixth embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a alkyl-substituted urea, wherein the alkyl-substituted
urea is capable of imparting a cooling sensation to an oral cavity
of a smoker upon inhalation of a smoke stream from the smoking
article, the smoke stream including the alkyl-substituted urea. The
alkyl-substituted urea can have a chemical formula corresponding
to: 4
[0020] In a seventh embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a sulfonamide, wherein the sulfonamide is capable of
imparting a cooling sensation to an oral cavity of a smoker upon
inhalation of a smoke stream from the smoking article, the smoke
stream including the sulfonamide. The sulfonamide can have a
chemical formula corresponding to: 5
[0021] In an eighth embodiment, a smoking article is provided, the
smoking article including a smokable material and a compound
including a phosphine oxide, wherein the phosphine oxide is capable
of imparting a cooling sensation to an oral cavity of a smoker upon
inhalation of a smoke stream from the smoking article, the smoke
stream including the phosphine oxide. The phosphine oxide can have
a chemical formula corresponding to: 6
[0022] In a ninth embodiment, a finished tobacco product is
provided, the finished tobacco product including a tobacco and a
compound including a carboxamide, a mentane glycerol ketal, a
menthyl ester, an alkyl-substituted urea, a sulfonamide, and a
phosphine oxide, wherein the compound is deposited on the tobacco,
and wherein the compound is capable of imparting a cooling
sensation to an oral cavity.
[0023] In a tenth embodiment, a finished tobacco product is
provided, the finished tobacco product including a tobacco and a
compound including a cyclic .alpha.-keto enamine, wherein the
compound is deposited on the tobacco, and wherein the compound is
capable of imparting a cooling sensation to an oral cavity.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Introduction
[0025] The following description and examples further illustrate
the preferred embodiments of the present invention. Those of skill
in the art will recognize that there are numerous variations and
modifications of this invention that are encompassed by its scope.
Accordingly, the description of preferred embodiments should not be
deemed to limit the scope of the present invention.
[0026] In preferred embodiments, methods and compositions for
imparting a feeling of freshness and coolness to the smoke stream
of a smoking article, such as a cigarette, are provided. The
methods and compositions utilize compounds of the class of cyclic
.alpha.-keto enamines. The compositions do not adversely affect the
taste of the cigarette while impart a sensation of "cooling" to the
oral cavity, however most impart such a sensation without the
"minty" odor characteristic of menthol. Compounds from the class of
cyclic .alpha.-keto enamines exhibiting a cooling effect have been
reported in the literature. See Ottinger, et al., J. Agric. Food
Chem., 2000, 49, 5383-5390. Other compounds that may exhibit a
cooling effect rendering them suitable for use as flavorants in
tobacco products include menthyl esters, for example: 7
[0027] The preferred embodiments relate to smoking articles such as
cigarettes, cigars, and pipe tobacco, and in particular to
cigarettes having a reduced content of various polyaromatic
hydrocarbons (PAHs), tobacco specific nitrosamines (TSNAs),
phenolic compounds, and certain other undesired components in
cigarette smoke, including both mainstream and sidestream smoke, or
cigarettes having a reduced content of TSNAs, nicotine, or other
undesired components in the uncombusted smoking product. The
tobacco products of preferred smoking articles may also include a
catalytic system including metallic or carbonaceous particles and a
source of nitrate or nitrite, as described in copending application
Ser. No. 10/007,724 filed on Nov. 9, 2001. The preferred smoking
articles typically incorporate activated charcoal filters, however
the compounds of preferred embodiments are also suitable for use
with unfiltered smoking articles.
[0028] While the compositions and methods of preferred embodiments
generally refer to tobacco, particularly in the form of cigarettes,
it is to be understood that such compositions and methods encompass
any smokable material or smokable composition, as will be apparent
to one skilled in the art.
[0029] Cyclic .varies.-Keto Enamines
[0030] In a preferred embodiment, the cooling agent is selected
from the class of compounds including cyclic .alpha.-keto enamines.
The class of cyclic .varies.-keto enamines includes compounds
characterized by the presence of the following moieties: 8
[0031] Although compounds containing five- and six-membered ketone
rings are generally preferred, rings containing additional carbon
atoms, e.g., 7, 8, 9, 10, or more carbon atoms, may also be
suitable. The hydrogen substituents on the ring may be replaced by
other substituents. Preferred substituents include alkyl groups,
particularly methyl and ethyl groups. Typically, from one to three
of the carbon atoms on the ring may be substituted with alkyl
substituents, and a particular carbon atom on the ring may include
up to two alkyl substituents. The nitrogen atom preferably is a
part of a piperidine, diethylamine, dibutylamine, dihexylamine,
morpholine, 1-proline methylester, or 1-proline group.
[0032] While alkyl groups are generally preferred as substituents
on the cyclopentenone or cyclohexanone ring, in certain embodiments
other hydrocarbyl substituents may also be suitable, including, but
not limited to, aryl, alkenyl, cycloalkyl, cycloalkenyl, bicyclic
or multicyclic hydrocarbyl groups, branched chains, straight
chains, combinations of any of the foregoing, and the like. The
hydrocarbyl groups may be substituted or unsubstituted, for
example, by one or more heteroatoms. In addition to one or two
carbon atom-containing hydrocarbyl groups, suitable hydrocarbyl
groups may also include a greater number of carbon atoms, for
example, 3, 4, 5, 6, 7, 8, 9, 10, or more carbon atoms. Examples of
such hydrocarbyl groups include, but are not limited to propyl,
isopropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, and higher.
In certain embodiments, it may be preferred to substitute one or
more hydrogen atoms on the cyclopentenone or cyclohexanone ring
with a heteroatom or heteroatom-containing moiety, for example, a
halogen such as fluorine, or an ester or ether group. From none to
all of the available hydrogens on the cyclopentenone or
cyclohexanone ring may be substituted.
[0033] While the nitrogen atom generally forms a part of one of the
above-mentioned functional groups (i.e., piperidine, diethylamine,
dibutylamine, dihexylamine, morpholine, 1-proline methylester, and
1-proline groups), in certain embodiments it may be desirable for
the nitrogen atom to form a part of other substituent groups. For
example, the nitrogen atom may be substituted by two or more of the
substituent groups described above as suitable substituents on the
cyclopentenone or cyclohexanone ring.
[0034] The chemical composition, number, and placement of
substituents or alteration(s) in ring size or constituents may have
an affect on cooling activity and/or odor, as discussed below.
Table 1 lists a number of cyclic keto enamines, including numerous
.alpha.-keto enamines, that may be suitable for use as cooling
agents in tobacco products. The cooling and odor threshold, as
determined in tap water using a triangle test, the odor quality,
and the ratio of cooling threshold to odor threshold are
reported.
1TABLE 1 Cyclic Keto Enamine Flavoring Agents Cooling Odor
Threshold Threshold Ratio Cmpd. Cyclic Keto Enamines (mg/kg)
(mg/kg) Odor Quality (cool/odor) 1
3-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one 29.0-43.5 43.5-72.5
faintly amine-like 0.8 2 5-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-
-1-one 4.5-9.0 2.6-5.2 faintly mint-like 1.7 3
3-methyl-2-(1-piperidinyl)-2-cyclopenten-1-one 60.0-100.0
80.0-120.0 faintly amine-like 0.8 4
3-methyl-2-diethylamino-2-cyclopenten-1-o- ne 30.0-50.0 2.0-3.0
carvone-like 10.0 5 5-methyl-2-(1-piperidinyl)-
-2-cyclopenten-1-one 16.0-24.0 12.0-20.0 faintly mint-like 2.7 6
5-methyl-2-diethylamino-2-cyclopenten-1-one 12.0-20.0 6.0-9.0
curcuma-like 2.1 7 5-methyl-2-dibutylamino-2-cyclopenten-1-one
48.4-67.8 2.4-2.8 mint-like 16.0 8 5-methyl-2-dihexylamino-2-cyclo-
penten-1-one -- -- -- -- 9
5-ethyl-2-(1-pyrrolidinyl)-2-cyclopenten- -1-one 26.7-42.5
13.4-22.4 faintly mint-like 2.0 10
(E)-4,5-dimethyl-2-(1-pyrrolidinyl)-2- 68.0-113.3 136.0-226.6
faintly mint-like 0.5 cyclopenten-1-one 11 3,5-dimethyl-2-(1-pyrro-
lidinyl)-2-cyclopenten-1-one 32.5-53.5 16.0-27.0 rubber-like 2.0 12
3,4-dimethyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one 51.3-85.5
25.7-42.8 rubber-like 2.0 13 3-(1-pyrrolidinyl)-2-cyclopenten-1-one
-- 234.0-390.0 odorless, bitter -- 14
2-methyl-3-(1-pyrrolidinyl)-2-c- yclopenten-1-one -- 92.0-138.0
odorless, bitter 8.0 15 2-(1-pyrrolidinyl)-2-cyclohexen-1-one
495.0-830.0 62.0-106.0 rubber-like 2.0 16
3-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one 90.5-150.8 45.2-75.4
faintly mint-like 32.0 17 3,5,5-trimethyl-2-(1-pyrrolidi- nyl)-2-
1605.0-2675.0 50.2-83.6 amine-like 8.0 cyclohexen-1-one 18
6-methyl-2-(1-pyrrolidinyl)-2-cyclohexen-1-one 26.9-44.8 3.4-5.6
rubber-like 4.0 19 4,4,6-trimethyl-2-(1-pyrrolidinyl)-2-
2213.0-3688.0 553.0-922.0 mint-like 4.0 cyclohexen-1-one 20
5-methyl-2-(1-morpholino)-2-cyclopenten-1-one 467.0-700.8
935.0-1558.0 rubber-like 0.5 21 (S)-5-methyl-2-(2-methoxycarbonyl--
1- 112.0-188.0 -- odorless <1 pyrrolidinyl)-2-cyclopenten-1-one
22 (S)-3-methyl-2-(2-carboxy-l-pyrrolidinyl)-2- 490.0-735.0 --
odorless <1 cyclopenten-1-one 23
5-methyl-4-(1-pyrrolidinyl)-3-(2H)-furanone 1.5-3.0 -- odorless
<0.01 24 2,5-dimethyl-4-(l-pyrrolidinyl)-3-(2H)- 100.0-140.0
30.0-60.0 nutty, roasty 2.7 furanone 25
4-methyl-3-(1-pyrrolidinyl)-- 2-(5H)-furanone 0.05-0.06 -- odorless
<0.01 26 4,5-dimethyl-3-(1-pyrrolidinyl)-2-(5H)- 2.0-4.0
32.0-64.0 faintly mint-like <0.1 furanone
[0035] Compounds 1 and 2 have been identified as active cooling
agents found in the dark malt formed from glucose and 1-proline in
Maillard reactions. The compounds have virtually no odor or taste,
but impart a long lasting sensation of coolness to the oral cavity.
Taste testing of Compounds 3-7 indicates that enlargement of the
pyrrolidine ring by one methylene group leads to a significant
decrease in cooling activity compared to Compounds 1 and 2. Opening
the-pyrrolidine ring does not substantially decrease the cooling
activity (Compound 6). However, increasing the size of the
aliphatic amino moiety by two methylene groups drastically
decreases the cooling activity of the compound (Compound 7), and
increasing the chain length of the amino moiety to six carbon atoms
completely diminishes the cooling activity (Compound 8). Insertion
of an additional methyl group or substitution of the methyl group
by an ethyl group on the cyclopentenone ring results in a
significant increase in cooling activity (Compounds 9 and 10
compared to Compound 2). Changing the position of the methyl
substituent has a small effect on cooling activity (compare
Compound 11 to Compounds 10 and 12). Changing the position of the
methyl group and the amino moiety (as in .beta.-keto enamines)
results in a loss of cooling activity (see Compounds 13 and 14).
Enlargement of the cyclopentenone ring leads to a significant
decrease in cooling activity (compare Compounds 16 and 18 to
Compounds 1 and 2). Subtraction of or insertion of additional
methyl groups significantly decreases cooling activity (compare
Compound 18 to Compounds 15 and 19). Incorporation of an oxygen
atom into the pyridine moiety substantially decreases the cooling
effect (see Compounds 20, 21, and 22). Substitution of the
methylene group at C(4) in Compound 1 results in a strong increase
in cooling activity (see Compound 23), and yields a compound with
no odor. Adding a second methyl group, however, produces a
significant decrease in cooling activity (compare Compound 24 to
Compounds 1 and 23). Changing the position of the oxygen atom in
the cyclopentenone ring, as in a .gamma.-lactone, dramatically
increases cooling activity (see Compounds 25-26) to a level
substantially higher than that observed for either Compound 1 or
(-)menthol.
[0036] On the basis of the ratio of cooling to odor, Compounds 23,
25, and 26 are suitable for use as odorless cooling agents (i.e.,
they possess a ratio of cooling to odor of <0.1). The data
reveal no clear association between a minty odor and cooling.
Compounds 1, 2, 23, and 25 demonstrate a high degree of cooling
effect, and have been identified as particularly preferred for use
in flavoring smoking articles.
[0037] Synthesis
[0038] The cooling agents of preferred embodiments may be
synthesized according to methods published in the literature. See,
e.g., Ottinger, et al., J. Agric. Food Chem., 2000, 49,
5383-5390.
[0039] Compounds 1-12 and 15-26 may be synthesized as follows. A
solution of the cyclic enolone (100 mmol) and the corresponding
amino compound (400 mmol) are refluxed in ethanol (600 mL) and
acetic acid (400 mmol) for 3 h. The cyclic enolone is selected as
follows: (E)-2-hydroxy-3,4-dimethyl-2-cyclo-penten-1-one (to
prepare Compound 10),
(E)-2-hydroxy-3,4-dimethyl-2-cyclo-penten-1-one (to prepare
Compound 12), 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (to prepare
Compound 24), 2-hydroxy-2-cyclohexen-1-one (to prepare Compound
15), 2-hydroxy-3,5,5-trimethyl-2-cyclo-hexen-1-one (to prepare
Compound 17), 2-hydroxy-3,5,5-trimethyl-2-cyclo-hexen-1-one (to
prepare Compound 19), 2-hydroxy-3,5-dimethyl-2-cyclopenten-1-one
(to prepare Compound 11), 2-hydroxy-3-ethyl-2-cyclopenten-1-one (to
prepare Compound 9), 2-hydroxy-3-methyl-2-cyclohexen-1-one (to
prepare Compounds 16 and 18),
2-hydroxy-3-methyl-2-cyclopenten-1-one (to prepare Compounds 3-8,
and 20-21), and 4-hydroxy-5-methyl-3-(2H)-furanone (to prepare
Compound 23). The amine is selected as follows: pyrrolidine (to
prepare Compounds 1, 2, 9, 12, 15-20, 23, and 24), piperidine (to
prepare Compounds 3 and 5), diethylamine (to prepare Compounds 4
and 6), dibutylamine (to prepare Compound 7), dihexylamine (to
prepare Compound 8), morpholine (to prepare Compound 20), 1-proline
methylester (to prepare Compound 21).
[0040] After cooling the solution to room temperature, the solvent
is removed under vacuum, the residue is taken up in water (300 mL),
and the pH is adjusted to 9 with sodium hydroxide solution (30% in
water). The solution is then extracted with diethyl ether
(5.times.150 mL), the combined organic layers are washed with an
aqueous solution of Na.sub.2CO.sub.3 (200 mL; 0.5 mol/L), dried
over Na2SO4, and then solvent is removed under vacuum. The residual
oil is dissolved in pentane/diethyl ether (8/2, v/v; 10 mL) and
then injected into a column (30.times.500 mm) packed with a slurry
of Al.sub.2O.sub.3 (basic activity III-IV, Merck, Darmstadt,
Germany) in pentane. Fractionation of the reaction products is
performed by chromatography using pentane/diethyl ether mixtures
with increasing diethyl ether content. Solvent is removed from the
fractions collected under vacuum to yield the target compounds as
colorless oils. The fractions may be identified by their
spectroscopic data. See Ottinger, et al., J. Agric. Food Chem.,
2000, 49, at 5384-5386.
[0041] To obtain Compounds 13 and 14, additional processing steps
are necessary. A solution of 3-hydroxy-2-cyclopenten-1-one (100
mmol) or 3-hydroxy-2-methyl-2-cyclopenten-1-one (100 mmol),
respectively, is refluxed in the presence of pyrrolidine (400
mmol), acetic acid (400 mmol), and ethanol (600 mL) for 4 h. After
cooling the solution to room temperature, the solvent is removed
under vacuum, the residue is taken up in water (300 mL), and the pH
is adjusted to 14 with concentrated sodium hydroxide solution. The
solution is then extracted with diethyl ether (5.times.150 mL) and
solvent is removed from the combined organic layers under vacuum.
The residual solid is recrystallized from diethyl ether, yielding
the target compounds as yellow crystals.
[0042] Compound 22 may be obtained as follows. A mixture of
2-hydroxy-3-methyl-2-cyclopenten-1-one (50 mmol) and 1-proline (80
mmol) are refluxed in ethanol (400 mL) for 4 h. After cooling the
sample to room temperature, the reaction mixture is taken up in
water (500 mL), filtered, and the pH is adjusted to 9 by adding an
aqueous sodium hydroxide solution (1 mol/L). The solution is
extracted with dichloromethane (5.times.200 mL), the aqueous layer
is freeze-dried, the residue is taken up in a mixture of methanol
and aqueous ammonium formate (15 mL; 5/95, v/v; pH 7.0; 0.1 mol/L),
and then fractionated by flash chromatography on RP-18 material
(15.0 g; Lichroprep 25-40 .mu.m, Merck, Darmstadt, Germany) using
the same solvent mixture as the mobile phase. After injection of
the crude material into the column and chromatography with an
eluent flow of 1.5 mL/min, the effluent of a peak detected at
.gamma.=300 nm after 5 h is collected. After evaporation of the
solvent and freeze-drying, the material is purified by RP-HPLC
using the following solvent gradient: after isocratic
chromatography with a mixture of methanol and aqueous ammonium
formate buffer (10/90, v/v; pH 7.0; 0.1 mol/L) for 10 min, the
methanol content is increased to 100% within 10 min. Monitoring the
effluent at 322 nm gives a peak at 9 min, which is collected in
several runs. The combined eluents are freeze-dried, yielding the
product (3.5 mmol; 7% in yield).
[0043] Compound 25 is prepared as follows. Diethyl oxalate (1.03
mol) and ethyl propionate (1.03 mol) are added dropwise to a
suspension of sodium ethoxide (1.00 mol) in diethyl ether (300 mL).
After refluxing the sample for 3 h, the reaction mixture is cooled
to room temperature, the solvent is removed under vacuum (45 mbar),
and the residue is taken up in water (160 mL). Formaldehyde (1.0
mol, 35% in solution) is added in small portions while the mixture
is cooled in a water bath. The reaction mixture is then heated for
1 h at 50.degree. C., the ethanol generated is removed under
vacuum, the solution is acidified with concentrated hydrochloric
acid (225 mL), water (60 mL) and hydroquinone (100 mg) are added,
and the mixture is refluxed for 4 h. The mixture is then cooled to
room temperature, extracted with ethyl acetate (5.times.100 mL),
and solvent is removed from the combined organic layers under
vacuum. The residue is recrystallized from diethyl ether, yielding
the product (38.8 g, 34% in yield) as white crystals.
[0044] Compound 26 may be prepared as follows.
3-hydroxy-4-methyl-2(5h)-fu- ranone (100 mmol), acetic acid (100
mmol), and pyrrolidine (100 mmol) is refluxed in ethanol (225 mL)
for 2.5 h., yielding the product.
[0045] Incorporation into Smoking Article
[0046] The cooling agent is typically applied to the smokable
material. If the smokable material is tobacco, it is convenient to
apply a solution or suspension of cooling agent to cut filler
before, during, or after the addition of the top flavor, or before,
during, or after application of the casing solution.
[0047] The cooling agent is preferably well dispersed throughout
the tobacco so as to provide uniform effectiveness throughout the
entire mass of smokable material and throughout the entire period
during which the material is smoked. In the case of cigarette
tobacco wherein a blend of various tobaccos is preferred, the
solution or suspension of cooling agent may be applied to one or
more of the blend constituents, or all of the blend constituents,
as desired. Preferably, the solution or suspension is applied to
all of the blend constituents so as to ensure substantially uniform
coverage.
[0048] It is preferred to apply the solution or suspension of
cooling agent to the smokable material in the form of a fine mist,
such as is produced using an atomizer. In a particularly preferred
embodiment, the solution or suspension is applied to tobacco,
preferably cut filler, in a rotating tumbler equipped with multiple
spray heads. Such a method of application ensures an even coating
of cooling agent on the tobacco product. The tobacco may be heated
before, during, or after application of the solution so as to
facilitate evaporation of excess solvent.
[0049] It is preferred to add a sufficient quantity of the cooling
agent to the smokable material to yield a satisfactory level of
cooling. Typically, the smokable material contains from about
0.0001 or less, 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.3,
0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 mg to about 100 mg or more
cooling agent per gram smokable material, preferably from about 2,
3, 4, or 5 mg to about 20, 30, 40, 50, 60, 70, 80, or 90 mg, and
more preferably from about 6, 7, 8, 9, or 10 mg to about 11, 12,
13, 14, 15, 16, 17, 18, or 19 mg. The amount of cooling agent
preferred may vary depending upon the cooling and odor properties
of the compound, including, but not limited to, the cooling
threshold, the odor threshold, odor quality, and ratio of cooling
threshold to odor threshold. The lower the cooling threshold, the
less cooling agent is required to produce an acceptable cooling
effect. In a particularly preferred embodiment, a typical full
flavored king size cigarette will contain sufficient cooling agent
to yield a cooling effect of the same magnitude as that delivered
in a typical mentholated full flavored king size cigarette.
[0050] In certain embodiments, it may be preferred to employ a
single compound to provide a cooling effect. In other embodiments,
it may be preferred to employ a combination of two or more of the
compounds of preferred embodiments. Likewise, it may be preferred
in certain embodiments to use a combination of (-)menthol and/or
another cooling substance, and one or more of the compounds of the
preferred embodiments. Combinations of compounds that take
advantage of the different cooling and/or odor characteristics of
the compounds may be preferred in order to provide a tailored
degree of cooling and/or a tailored flavor.
[0051] Once the cooling agent has been applied, the smokable
material may be further processed and formed into any desired shape
or used loosely, for example, in cigars, cigarettes, and pipe
tobacco, in any suitable manner as is well-known to those skilled
in the art.
[0052] The Filter
[0053] In preferred embodiments, a filter for tobacco smoke is
provided for the smoking article. The filter can be provided in
combination with cigarettes or cigars or other smokable devices
containing divided tobacco. Preferably, the filter is secured to
one end of the smokable device, positioned such that smoke produced
from the tobacco passes into the filter before entering the smoker.
The filter can also be provided by itself, in a form suitable for
attachment to a cigarette, cigar, pipe, or other smokable
device.
[0054] The filter according to preferred embodiments advantageously
removes at least some amount of an undesired component from tobacco
smoke. Undesired components in tobacco smoke may include permanent
gases, organic volatiles, semivolatiles, and nonvolatiles.
Permanent gases (such as carbon dioxide) make up 80 percent of
smoke, and are generally unaffected by filtration or adsorption
materials. The levels of organic volatiles, semivolatiles, and
nonvolatiles may be reduced by filters of various designs. The
filters according to preferred embodiments may advantageously
remove undesired components including, but not limited to, tar,
nicotine, carbon monoxide, nitrogen oxides, HCN, acrolein,
nitrosamines, polyaromatic hydrocarbons, particulates, oils,
various carcinogenic substances, and the like.
[0055] The filter preferably permits satisfactory or improved smoke
flavor, nicotine content, and draw characteristics. The filter is
preferably designed to be acceptable to the user, being neither
cumbersome nor unattractive. Filters according to preferred
embodiments may be made of inexpensive, safe, and effective
components, and may preferably be manufactured with standard
cigarette manufacturing machinery.
[0056] The filter may incorporate one or more materials capable of
absorbing, adsorbing, or reacting with at least one undesirable
component of tobacco smoke. Such absorbing, adsorbing, or reacting
materials may be incorporated into the filter using any suitable
method or device. In a preferred embodiment, the absorbing,
adsorbing, or reacting material may be contained within a
smoke-permeable cartridge to be placed within the filter, or
contained within a cavity within the filter. In another embodiment,
the absorbing, adsorbing, or reacting material is deposited or
applied on and/or in the filter material.
[0057] Application methods may include forming a paste of the
absorbing, adsorbing, or reacting material in a suitable liquid,
applying the paste to the filter material, and allowing the liquid
to evaporate. Alternatively, the absorbing, adsorbing, or reacting
material may be mixed with an adhesive substance and applied to the
filter material. All of the filter material may include the
absorbing, adsorbing, or reacting material, or only a portion of
the filter material may include the adsorbing or reacting
material.
[0058] The cigarette filters of the preferred embodiments
preferably include activated carbon (commonly referred to as
charcoal) as an adsorbing material. The process by which activated
carbon removes compounds is adsorption, which is a different
process than absorption. Absorption is the process whereby
absorbates are dispersed throughout a porous absorbent, while
adsorption is a surface attraction effect. Both adsorption and
absorption can be physical or chemical effects. The adsorptive
effect associated with activated carbon is mainly a physical
effect. In activated carbon filters, smoke compounds in the organic
volatile and semivolatile phases diffuse through the carbon
particles, move over the surface and then move into the activated
carbon pores compelled by a phenomenon known as Van der Waal's
forces. Although these forces are generally considered weak, at
very short range (one or two molecular diameters), they are strong
enough to attract and effectively hold smoke components.
[0059] Activated carbon may be obtained from a variety of sources,
including, but not limited to, wood, coconut shells, coal, and
peat. Wood generally produces soft and macroporous activated carbon
(pores from 50 to 1,000 nm in diameter). Peat and coal materials
generally produce activated carbon that is predominantly mesoporous
(pores 2 to 50 nm in diameter). Activated carbon derived from
coconut shells is generally microporous (pores of less than 2 nm in
diameter), has a large surface area, and has a low ash and base
metal content when compared to certain other types of activated
carbon.
[0060] Preferred activated carbons are microporous and have a high
density, which imparts improved structural strength to the
activated carbon so that it can resist excessive particle abrasion
during handling and packaging.
[0061] The filters of preferred embodiments may also contain
various other adsorptive, absorptive, or porous materials in
addition to activated carbon as described above. Examples of such
materials, include, but are not limited to, cellulosic fiber, for
example, cellulose acetate, cotton, wood pulp, and paper; polymeric
materials, for example, polyesters and polyolefins; ion exchange
materials; natural and synthetic minerals such as activated
alumina, silica gel, and magnesium silicate; natural and synthetic
zeolites and molecular sieves (see, for example U.S. Pat. No.
3,703,901 to Norman et al.); natural clays such as meerschaum;
diatomaceous earth; activated charcoal and other materials as will
be understood by those with skill in the art. The adsorptive,
absorptive, or porous material may be any nontoxic material
suitable for use in filters for smokable devices that are
compatible with other substances in the smoking device or smoke to
be filtered.
[0062] Typically, the filter element may include as the major
component a porous material, for example, cellulose acetate tow or
cellulosic paper, referred to below as a "filter material." The
adsorptive or absorptive component, often a granular or particulate
substance such as activated carbon, is generally dispersed within
the porous filter material of the filter segment or positioned
within a cartridge or cavity (for example, within a cavity of a
triple filter, as discussed below).
[0063] The filter material may have the form of a non-woven web of
fibers or a tow. Alternatively, the filter material may have a
sheet-like form, particularly when the material is formed from a
mixture of polymeric or natural fibers, such as cotton or wood
pulp. Filter material in web or sheet-like form can be gathered,
folded, crimped, or otherwise formed into a suitable (for example,
cylindrical) configuration using techniques which will be apparent
to one skilled in the art. See, for example, U.S. Pat. No.
4,807,809 to Pryor et al.
[0064] In preferred embodiments, the filter material constitutes
cellulose acetate tow or cellulose paper. Cellulose acetate tow is
the most widely preferred filter material in cigarettes worldwide.
Cellulose paper filter materials generally provide better tar and
nicotine retention than do acetate filters with a comparable
pressure drop, and have the added advantage of superior
biodegradability. Cellulose and cellulose acetate reduce the amount
of chemicals in the semivolatile phase and the nonvolatile phase,
which is composed of solid particulates (commonly referred to as
"tar"). These compounds are reduced in direct proportion to the
amount of cellulose or cellulose acetate in the filter. Increasing
density of the cellulose or cellulose acetate generally means
increasing the pressure drop, which increases the filter retention
and therefore decreases tar delivery. Filters retain generally less
than 10 percent of vapor phase components.
[0065] In certain embodiments, it may be preferred to use a
polymeric material such as cellulose acetate as the filter material
rather than a material such as cellulose paper. Polymeric materials
may be preferred in embodiments wherein superior chemical inertness
or structural integrity during use are desired attributes of the
filter, for example, when certain smoke-altering components
reactive to cellulose paper are present in the filter, or when
components reactive to cellulose paper are generated within the
filter. Cellulose acetate tow (such as that available from Celanese
Acetate of Charlotte, N.C.) is the most commonly preferred
polymeric material, however suitable polymeric materials may
include other synthetic addition or condensation polymers, such as
polyamides, polyesters, polypropylene, and polyethylene.
[0066] The polymeric material may be any nontoxic polymer suitable
for use in filters for smokable devices that are compatible with
other substances in the smoking device or smoke to be filtered, and
which possess the desired degree of inertness. The polymeric
material is preferably in fibrous tow form, but may optionally be
in other physical forms, for example, crimped sheet. The polymeric
material may constitute a single polymer or a mixture of different
polymers, for example, two or more of components such as
homopolymers, copolymers, terpolymers, functionalized polymers,
polymers having different molecular weights, polymers constituting
different monomers, polymers constituting two or more of the same
monomers in different proportions, oligomers, and nonpolymeric
components. The polymer may also be subjected to suitable
pre-treatment or post-treatment steps, for example,
functionalization of the polymer, coating with suitable materials,
and the like.
[0067] When polymeric fibers are employed as the filter material,
they can make up all or a portion of the composition of the filter
material of the filter. Alternatively, the filter material can be a
mixture or blend of polymer fibers, or a mixture or blend of
polymer fibers and nonpolymeric fibers, for example, cellulose
fibers obtained from wood pulp, purified cellulose, cotton fibers,
and the like. A mixture of filter materials may be preferred in
certain embodiments where it is desired to reduce materials costs,
as polymeric materials may be more expensive than natural fibers.
Any suitable proportion of polymeric material may be present, for
example from 100% by weight polymeric material down to 80, 60, 50,
40, 30, 25, 20, 15, or 10% by weight or less polymeric
material.
[0068] As discussed above, in certain embodiments it may be
desirable to coat the filter material with one or more substances
that may react chemically with an undesirable component of the
smoke. Such substances may include natural or synthetic polymers,
or chemicals known in the art to provide for a treated filter
material capable of altering the chemistry of tobacco smoke. One
method for coating the filter material is to prepare a solution or
dispersion of the substance with a suitable solvent. Suitable
solvents may include, for example, water, ethanol, acetone, methyl
ethyl ketone, toluene, and the like.
[0069] The solution or dispersion can be applied to the surface of
the filter material using gravure techniques, spraying techniques,
printing techniques, immersion techniques, injection techniques,
and the like. Most preferably, the filter material is essentially
insoluble in the preferred solvent, and as such does not
substantially affect the general structure of the filter material.
After the solution or dispersion is applied to the surface of the
filter material, the solvent is removed, typically by air-drying at
room temperature or heating, for example, in a convection or
forced-air oven. The amount of solution or dispersion which is
applied to the filter material is typically sufficient to cover the
outer surface of the filter material, but not sufficient to fill
the void spaces between the fibers of filter material.
[0070] Typically, the amount of solution or dispersion applied to
the filter material is sufficient to deposit at least about 5
percent, preferably at least about 8 percent, more preferably at
least about 10 percent, and most preferably at least about 15
percent of the substance, based on the weight of the filter
material prior to treatment.
[0071] When the substance is a polymer, the polymer can be
synthetic polymer or a natural polymer. Synthetic polymers are
derived from the polymerization of monomeric materials (for
example, addition or condensation polymers) or are isolated after
chemically altering the substituent groups of a polymeric material.
Natural polymers are isolated from organisms (for example, plants
such as seaweed), usually by extraction.
[0072] Exemplary synthetic polymers that may be applied to filter
materials include, but are not limited to, carboxymethylcellulose,
hydroxypropylcellulose, cellulose esters such as cellulose acetate,
cellulose butyrate and cellulose acetate propionate (for example,
from Eastman Chemical Corporation of Kingsport, Tenn.),
polyethylene glycols, water dispersible amorphous polyesters with
aromatic dicarboxylic acid functionalities (for example, Eastman
AQs from Eastman Chemical Corporation), ethylene vinyl alcohol
copolymers (for example, from Mica Corp. of Shelton, Conn.),
partially or fully hydrolyzed polyvinyl alcohols (for example, the
Airvols from Air Products and Chemicals of Allentown, Pa.),
ethylene acrylic acid copolymers (for example, Envelons from Rohm
and Haas of Philadelphia, Pa. and Primacors from The Dow Chemical
Co. of Wilmington, Del.), polysaccharides (for example, Keltrol
from CP Kelco of San Diego, Calif.), alginates (for example, from
International Specialty Products of Wayne, N.J.), carrageenans (for
example, Viscarin GP109 and Nutricol GP120F konjac flour from FMC)
and starches (for example, Nadex 772, K-4484 and N-Oil from
National Starch & Chemical Co.).
[0073] Typically, natural or synthetic polymers tend to coat the
surface of the filter material very efficiently, and have a high
viscosity, making high coating levels unnecessary and sometimes
difficult. Typically, certain natural or synthetic polymers can be
applied to the filter material at levels of at least about 0.001
percent, preferably at least about 0.01 percent, more preferably at
least about 0.1 percent, and most preferably at least about 1
percent, based on the weight of the filter material prior to
treatment. Typically, the amount of certain natural or synthetic
polymers applied to the filter material does not exceed about 10
percent, and normally does not exceed about 5 percent, based on the
weight of the filter material prior to treatment.
[0074] The natural or synthetic polymeric material that is applied
to the filter material can vary, depending upon factors such as the
chemical functionality, hydrophilicity, or hydrophobicity desired.
If desired, more than one type of natural or synthetic polymer can
be applied to the filter material in a single dispersion or
solution. If desired, the filter material can have at least one
type of natural or synthetic polymer dissolved or dispersed in a
suitable solvent applied thereto and the solvent removed, after
which the resulting coated filter material has at least one other
natural or synthetic polymer applied in similar fashion. If
multiple applications are conducted in this way, it is desirable
that the solvent or solvents do not substantially dissolve any
natural or synthetic polymer already coated onto the filter
material.
[0075] Filters of preferred embodiments may include more than one
segment. One configuration of such filters is the dual filter,
wherein the filter constitutes two different segments, with one
segment adjacent to the mouth and the other segment of the filter
adjacent to the tobacco rod. A common type of dual filter is one
wherein a cellulose acetate segment is situated on the mouth side
of the filter, and a cellulose paper segment is situated on the
side of the filter adjacent to the tobacco rod. Activated charcoal
may be incorporated into the cellulose paper segment of the filter
to assist in removal of undesired components from tobacco
smoke.
[0076] Another filter configuration, referred to as a triple
filter, has three segments, including a segment adjacent to the
mouth, a segment adjacent to the tobacco rod, and a segment
situated between the two other segments. The different segments may
be prepared from different materials, or may be materials having
the same composition but different physical form, for example,
crimped sheet and tow, or may be materials having the same
composition and physical form, but wherein one segment contains an
additional component not present in another segment. A common
triple filter configuration includes two segments selected from one
or both of cellulose acetate and cellulose, one adjacent to the
mouth and one adjacent to the filter, with a segment in between
containing a smoke-altering component. Examples of smoke-altering
components include activated carbon or other absorbents, or
components imparting flavor to the smoke.
[0077] One variety of triple filter is the cavity filter. The
cavity filter is composed of two segments separated by a cavity
containing one or more smoke-altering components. The cavity may
contain an adsorbent material as described above, optionally in
combination with other suitable components such as activated
charcoal.
[0078] Dual and triple filters may be symmetrical (all filter
segments are the same length) or asymmetrical (two or more segments
are of different lengths). Filters may be recessed, with an open
cavity on the mouth side, reinforced by an extra stiff plug wrap
paper.
[0079] When the filter element contains a solid material in a form
other than tow or sheet, it may be incorporated into the filter
element using any suitable method or device, such as those
described above for incorporating an absorbing, adsorbing, or
reacting material into the filter element. Liquids may be
incorporated into the porous filter material by immersing the
filter material in the liquid, spraying the liquid onto the filter
material, or combining the liquid with another component, for
example, a component capable for forming a gel or a solid, then
applying the liquid-containing substance to the porous filter
material using methods well known to those skilled in the art.
[0080] The form of the filter material and the configuration of the
filter material, as well as the filtration efficiency for
particulate matter and vapor phase components of each segment of
the filter element may be varied so as to yield the desired balance
of performance characteristics for the filter element, as will be
recognized by those skilled in the art. Filter materials in tow
form can be processed and manufactured into filter rods using known
techniques. Filter materials in sheet-like or web form can be
formed into filter rods using techniques described in U.S. Pat. No.
4,807,809 to Pryor et al., and U.S. Pat. No. 5,074,320 to Jones,
Jr. et al. Filter materials also can be formed into rods using a
rod-making unit (for example, from Molins Tobacco Machinery, Ltd.
of Bucks, United Kingdom).
[0081] The porous filter material may contain various additional
minor components. These components may include pigments, dyes,
preservatives, antioxidants, defoamers, solvents, lubricants,
waxes, oils, resins, adhesives, and other materials, as are known
in the art.
[0082] In a preferred embodiment, the smoking article is provided
with a cavity filter composed of two cellulose acetate segments
separated by a cavity containing activated charcoal, wherein the
filter segments are wrapped in a paper plug wrap. The plug wrap may
be provided with perforations in the cellulose acetate segment
adjacent to the tobacco rod if air dilution is desired, for
example, for low or ultra-low tar cigarettes. The cellulose acetate
segment adjacent to the tobacco rod is preferably about 9 mm in
length, the mouth end segment is preferably 11 mm in length, and
the cavity is preferably 5 mm in length. The cavity is preferably
substantially filled. Substantially filled generally refers to a
cavity segment wherein more than about 95 vol. % is filled with
packed particles, preferably more than about 96, 97, 98, or 99 vol.
% is filled with packed particles, and most preferably about 100
vol. % is filled with packed particles. However, in certain
embodiments it may be desirable for the cavity to be less than
substantially filled, for example, less than about 95, 94, 93, 92,
91, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15,
10, or 5 vol. % or less. In a preferred embodiment, the cavity is
substantially filled with one type of activated charcoal. However,
in certain other embodiments the activated charcoal may constitute
a mixture of activated charcoals (for example, charcoals of varying
particle size or source), or the activated charcoal may be mixed or
combined with one or more inert ingredients, such as magnesium
silicate (available as CAVIFLEX.TM. and SEL-X-4.TM. from
Baumgartner, Inc. of Melbane, N.C.), inert carbon, or semolina.
Most preferably, the cavity segment contains 0.1 g of a single type
of activated charcoal as the sole component in a 5 mm long cavity
segment of filter. In various embodiments various types of
activated charcoal or carbon prepared from different starting
materials, having different surface area and particle size, or
having different properties may be preferred. Suitable activated
carbons, including specialty activated carbons, may be obtained
from Calgon Carbon Corporation of Pittsburgh, Pa.
[0083] Additives
[0084] Additional components, as are known in the art, may also be
added to the smokable material, or may be contained within the
filter, the tobacco rod, or other components of the smoking
articles of preferred embodiments. Nonlimiting examples of such
components include tobacco extracts, lubricants, flavorings, and
the like. These additional components preferably do not react with
the cooling compounds of preferred embodiments in such a way as to
substantially reduce its effectiveness in yielding a cooling effect
during use of the smoking article. To the extent that such
reactions do occur, they can be compensated for by alterations in
the concentration or the type of the cooling compound and/or other
components present.
[0085] The filter element optionally can include a tobacco or
flavor extract in intimate contact with the filter material. If
desired, the tobacco or flavor extract can be spray dried and/or
subjected to heat treatment. The filter element prior to smoking
may include less than about 10% tobacco or flavor extract to more
than 50% percent tobacco or flavor extract, based on the total dry
weight of the filter element and extract. In some embodiments, the
tobacco filter elements typically include a lubricating substance
in intimate contact with the filter material. Normally, prior to
smoking the cigarette, the filter element includes at least about
0.1 percent lubricating substance, based on the weight of the
filter material of that segment. The lubricating substance can be a
low molecular weight liquid (for example, glycerine) or a high
molecular weight material (for example, an emulsifier).
[0086] Flavorants in addition to the cooling compounds of preferred
embodiments, even flavorants such as menthol itself, can be
incorporated into the cigarette using techniques familiar to the
skilled artisan. If desired, flavor additives such as organic acids
can be incorporated into the cigarette as additives to cut filler.
See, for example, U.S. Pat. No. 4,830,028 to Lawson et al. The
flavor extract may typically be included at a level of from about
5% or less to about 50% or more of the total dry weight of the
filter element and the extract, preferably from about 10% to about
45%, and more preferably from about 15%, 20%, or 25% to about 30%,
35%, or 40%.
[0087] The Smokable Material
[0088] The cooling compounds may be used in conjunction with any
suitable smokable material. Examples of preferred smokable
materials are the tobaccos that include but are not limited to
Oriental, Virginia, Maryland, and Burley tobaccos, as well as the
rare and specialty tobaccos. The tobacco plant may be a variety
produced through conventional plant breeding methods, or may be a
genetically engineered variety. Low nicotine and/or low TSNAs
tobacco varieties, including genetically engineered varieties, are
especially preferred. The tobacco may be cured using any acceptable
method, including, but not limited to, flue-curing, air-curing,
sun-curing, and the like, including curing methods resulting in low
nitrosamine levels, such as the curing methods disclosed in U.S.
Pat. Nos. 6,202,649 and 6,135,121 to Williams.
[0089] Generally, the tobacco material is aged. The cured or
uncured tobacco may be subjected to any suitable processing step,
including, but not limited to, microwave or other radiation
treatment, treatment with ultraviolet light, or extraction with an
aqueous or nonaqueous solvent.
[0090] The tobacco can be in the form of tobacco laminae, processed
tobacco stems, reconstituted tobacco material, volume expanded
tobacco filler, or blends thereof. The type of reconstituted
tobacco material can vary. Certain suitable reconstituted tobacco
materials are described in U.S. Pat. No. 5,159,942 to Brinkley et
al. Certain volume expanded tobacco materials are described in U.S.
Pat. No. 5,095,922 to Johnson et al. Blends of the aforementioned
materials and tobacco types can be employed. Exemplary blends are
described in U.S. Pat. No. 5,074,320 to Jones, Jr. et al. Other
smokable materials, such as those smokable materials described in
U.S. Pat. No. 5,074,321 to Gentry et al., and U.S. Pat. No.
5,056,537 to Brown et al., also can be employed.
[0091] The smokable materials generally are employed in the form of
cut filler as is common in conventional cigarette manufacture. For
example, the smokable filler material can be employed in the form
of pieces, shreds, and/or strands cut into widths ranging from
about {fraction (1/60)} inch (0.04 mm) to about 1/5 inch (5 mm),
preferably from about {fraction (1/40)} inch (0.6 mm) to about
{fraction (1/20)} inch (1.3 mm). Generally, such pieces have
lengths between about 0.25 inch (6 mm) and about 3 inches (76 mm).
In certain embodiments, however, it may be preferred to use cut
filler having widths less than about {fraction (1/60)} inch (0.04
mm) or more than about 1/5 inch (5 mm), and lengths less than about
0.25 inch (6 mm) or more than about 3 inches (76 mm).
[0092] The smokable material can have a form (for example, a blend
of smokable materials, such as a blend of various types of tobacco
in cut filler form) having a relatively high nicotine content. Such
a smokable material typically has a dry weight nicotine content
above about 2.0%, 2.25%, 2.5%, 2.75%, or 3.0% or more. Such
smokable materials are described in U.S. Pat. No. 5,065,775 to
Fagg.
[0093] Alternatively, the smokable material can have a form having
a relatively low or negligible nicotine content. Such a smokable
material typically has a dry weight nicotine content below about
1.5%, 1.25%, 1.0%, 0.75%, 0.5%, 0.1%, 0.05% or less. Tobacco having
a relatively low nicotine content is described in U.S. Pat. No.
5,025,812 to Fagg et al.
[0094] As used herein, the term "dry weight nicotine content" in
referring to the smokable material refers to the mass of alkaloid
nicotine as analyzed and quantitated by spectroscopic techniques
divided by the dry weight of the smokable material analyzed. See,
for example, Harvey et al., Tob. Sci., Vol. 25, p. 131 (1981).
[0095] In a preferred embodiment, the smokable material constitutes
a tobacco product obtained from tobacco plants that are
substantially free of nicotine and/or tobacco-specific
nitrosamines. Tobaccos that may be substantially free of nicotine
or TSNAs may be produced by interrupting the ability of the plant
to synthesize nicotine using genetic engineering. Copending PCT
Application No. PCTUS02/18040 filed Jun. 6, 2002 and PCT
Publication No. WO9856923 to Conkling et al. describe tobacco that
is substantially free of nicotine and TSNAs that is made by
exposing at least one tobacco cell of a selected variety to an
exogenous DNA construct having, in the 5' to 3' direction, a
promoter operable in a plant cell and DNA containing a portion of a
DNA sequence that encodes an enzyme in the nicotine synthesis
pathway. The DNA is operably associated with the promoter, and the
tobacco cell is transformed with the DNA construct, the transformed
cells are selected, and at least one transgenic tobacco plant is
regenerated from the transformed cells. The transgenic tobacco
plants contain a reduced amount of nicotine and/or TSNAs as
compared to a control tobacco plant of the same variety. In
preferred embodiments, DNA constructs having a portion of a DNA
sequence that encodes an enzyme in the nicotine synthesis pathway
may have the entire coding sequence of the enzyme, or any portion
thereof.
[0096] In a preferred embodiment, the smokable material constitutes
a tobacco product obtained from tobacco plants that have reduced
nicotine content and/or TSNAs such as those described in copending
application Ser. No. 09/941,042, filed Aug. 28, 2001.
[0097] Tobacco products having specific amounts of nicotine and/or
TSNAs may be created through blending of low nicotine/low TSNAs
tobaccos, such as those described above, with conventional
tobaccos. Some blending approaches begin with tobacco prepared from
varieties that have extremely low amounts of nicotine and/or TSNAs.
By blending prepared tobacco from a low nicotine/low TSNAs variety
(for example, undetectable levels of nicotine and/or TSNAs) with a
conventional tobacco (for example, Burley, which has 30,000 parts
per million (ppm) nicotine and 8,000 parts per billion (ppb) TSNAs;
Flue-Cured, which has 20,000 ppm nicotine and 300 ppb TSNAs; and
Oriental, which has 10,000 ppm nicotine and 100 ppb TSNAs), tobacco
products having virtually any desired amount of nicotine and/or
TSNAs can be manufactured. Tobacco products having various amounts
of nicotine and/or TSNAs can be incorporated into tobacco use
cessation kits and programs to help tobacco users reduce or
eliminate their dependence on nicotine and reduce the carcinogenic
potential.
[0098] For example, a step 1 tobacco product can constitute
approximately 25% low nicotine/low TSNAs tobacco and 75%
conventional tobacco; a step 2 tobacco product can constitute
approximately 50% low nicotine/low TSNAs tobacco and 50%
conventional tobacco; a step 3 tobacco product can constitute
approximately 75% low nicotine/low TSNAs tobacco and 25%
conventional tobacco; and a step 4 tobacco product can constitute
approximately 100% low nicotine/low TSNAs tobacco and 0%
conventional tobacco. A tobacco use cessation kit can include an
amount of tobacco product from each of the aforementioned blends to
satisfy a consumer for a single month program. That is, if the
consumer is a one pack a day smoker, for example, a single month
kit provides 7 packs from each step, a total of 28 packs of
cigarettes. Each tobacco use cessation kit may include a set of
instructions that specifically guide the consumer through the
step-by-step process. Of course, tobacco products having specific
amounts of nicotine and/or TSNAs may be made available in
conveniently sized amounts (for example, boxes of cigars, packs of
cigarettes, tins of snuff, and pouches or twists of chew) so that
consumers could select the amount of nicotine and/or TSNAs they
individually desire. There are many ways to obtain various low
nicotine/low TSNAs tobacco blends using the teachings described
herein and the following is intended merely to guide one of skill
in the art to one possible approach.
[0099] To obtain a step 1 tobacco product, which is a 25% low
nicotine/low TSNAs blend, prepared tobacco from an approximately 0
ppm nicotine/TSNAs tobacco can be mixed with conventional Burley,
flue-cured, or Oriental in a 25%/75% ratio respectively to obtain a
Burley tobacco product having 22,500 ppm nicotine and 6,000 ppb
TSNAs, a flue-cured product having 15,000 ppm nicotine and 225 ppb
TSNAs, and an Oriental product having 7,500 ppm nicotine and 75 ppb
TSNAs. Similarly, to obtain a step 2 product, which is 50% low
nicotine/low TSNAs blend, prepared tobacco from an approximately 0
ppm nicotine/TSNAs tobacco can be mixed with conventional Burley,
flue-cured, or Oriental in a 50%/50% ratio respectively to obtain a
Burley tobacco product having 15,000 ppm nicotine and 4,000 ppb
TSNAs, a flue-cured product having 10,000 ppm nicotine and 150 ppb
TSNAs, and an Oriental product having 5000 ppm nicotine and 50 ppb
TSNAs. Further, a step 3 product, which is a 75%/25% low
nicotine/low TSNAs blend, prepared tobacco from an approximately 0
ppm nicotine/TSNAs tobacco can be mixed with conventional Burley,
flue-cured, or Oriental in a 75%/25% ratio respectively to obtain a
Burley tobacco product having 7,500 ppm nicotine and 2,000 ppb
TSNAs, a flue-cured product having 5,000 ppm nicotine and 75 ppb
TSNAs, and an Oriental product having 2,500 ppm nicotine and 25 ppb
TSNAs.
[0100] It is appreciated that tobacco products are often a blend of
many different types of tobaccos, which are grown in many different
parts of the world under various growing conditions. As a result,
the amount of nicotine and TSNAs may differ from crop to crop.
Nevertheless, by using conventional techniques one can easily
determine an average amount of nicotine and TSNAs per crop used to
create a desired blend. By adjusting the amount of each type of
tobacco that makes up the blend one of skill can balance the amount
of nicotine and/or TSNAs with other considerations such as
appearance, flavor, and smokability. In this manner, a variety of
types of tobacco products having varying level of nicotine and/or
nitrosamines, as well as appearance, flavor, and smokability can be
created. Such types of tobacco products may behave in similar
manners when the cooling compounds of preferred embodiments are
applied thereto.
[0101] While in the preferred embodiments the cooling compounds are
used in conjunction with a smokable material including tobacco, any
other smokable materials may preferred in other embodiments. For
example, the smokable plant materials may include various herbal
smoking materials. Mullein and Mugwort are commonly preferred base
materials in blends of herbal smoking materials. Some other
commonly preferred plant materials that are also smokable materials
include Willow bark, Dogwood bark, Pipsissewa, Pyrola, Kinnikinnik,
Manzanita, Madrone Leaf, Blackberry, Raspberry, Loganberry,
Thimbleberry, and Salmonberry.
[0102] The Wrapping Material
[0103] Various wrapping materials that circumscribe the charge of
smokable material may be employed. Examples of suitable wrapping
materials include cigarette paper wrappers available from
Schweitzer-Mauduit International in Alpharetta, Ga. Cigarette paper
wraps the column of tobacco in a cigarette and can be made from
flax, wood, or a combination of fibers. Certain properties such as
basis weight, porosity, opacity, tensile strength, texture, ash
appearance, taste, brightness, good gluing, and lack of dust are
selected to provide optimal performance in the finished product, as
well as to meet runnability standards of the high-speed production
processes preferred by cigarette manufacturers.
[0104] A more porous paper is one that allows air to easily pass
into a cigarette. Porosity is measured in Coresta units and can be
controlled to determine the rate and direction of airflow through
the cigarette. The higher the number of Coresta units, the more
porous the paper. Tar and nicotine yields are commonly controlled
without altering the flavor of the cigarette through the choice of
paper. The use of highly porous papers can help create lower tar
levels in a cigarette. Higher paper porosity increases the
combustibility of a cigarette by adding more air to the process,
which increases the heat and the burning rate. A higher burn rate
may lower the number of puffs that a smoker takes per cigarette.
Papers having porosities up to 200 Coresta units or higher are
generally preferred, however different kinds of cigarettes may use
papers of different preferred porosities. For example,
American-blend cigarettes typically use 40 to 50 Coresta unit
papers. Flue-cured tobacco cigarettes, which burn slower, generally
use higher porosities, ranging from 60 to 80 Coresta unit papers.
Higher porosities may be obtained by electronically perforating
(EP) the paper.
[0105] Cigarette papers are available that are prepared from
various base fibers. Flax and wood are commonly preferred base
fibers. In addition to 100% flax and 100% wood papers, papers are
also available with flax and wood fibers mixed in various ratios.
Wood based papers are widely preferred because of their low cost,
however certain consumers prefer the taste of flax based
papers.
[0106] Suitable cigarette papers may be obtained from RFS (US)
Inc., a subsidiary of privately-held PURICO (IOM) Limited of the
United Kingdom, which is the current owner of P. H. Glatfelter
Company's Ecusta mill which manufactures tobacco papers. In
preferred embodiments, a paper having a porosity of about 26
Coresta EP to 90 Coresta EP is preferred. Suitable papers include
Number 409 papers having a porosity of 26 Coresta and 0.85% citrate
content, and Number 00917 papers having a porosity of 26 Coresta
EP. However, in certain embodiments, it may be preferred to use a
paper having a lower air permeability, for example, a paper that
has not been subjected to electronic perforation and which has a
low inherent porosity, for example, less than 26 Coresta.
[0107] In preferred embodiments, the cigarette paper is suitable
for use in "self-extinguishing" cigarettes. Examples of cigarette
papers suitable for use in self-extinguishing cigarettes include,
for example, papers saturated with a citrate or phosphate fire
retardant or incorporating one or more fire retardant bands along
the length of the paper. Such papers may also include thicker
papers of reduced flammability.
[0108] Wrapping materials described in U.S. Pat. No. 5,220,930 to
Gentry may be preferred in certain embodiments. More than one layer
of circumscribing wrapping material can be employed, if desired.
See, for example, U.S. Pat. No. 5,261,425 to Raker et al. Other
wrapping material includes plug wrap paper and tipping paper. Plug
wrap paper wraps the outer layer of the cigarette filter plug and
holds the filter material in cylindrical form. Highly porous plug
wrap papers are preferred in the production of filter-ventilated
cigarettes.
[0109] Tipping paper joins the filter element with the tobacco rod.
Tipping papers are typically made in white or a buff color, or in a
cork pattern, and are both printable and glueable at high speeds.
Such tipping papers are used to produce cigarettes that are
distinctive in appearance, as well as to camouflage the use of
activated carbon in the filter element. Pre-perforated tipping
papers are commonly preferred in filter-ventilated cigarettes.
[0110] In the case of cigars, reconstituted tobacco wrapper is
often wrapped around the outside of machine-made cigars to provide
a uniform, finished appearance. The wrapper material can
incorporate printed veins to give the look of natural tobacco leaf.
Such wrapper material is manufactured utilizing tobacco leaf
by-products. Reconstituted tobacco binder holds the "bunch" or
leaves of tobacco in a cylindrical shape during the production of
machine-made cigars. Reconstituted tobacco binder is also
manufactured utilizing tobacco leaf by-products.
[0111] An extremely small amount of a sideseam adhesive is
preferred to secure the ends of the cigarette paper wrapper around
the tobacco rod (and filter element, if present). Any suitable
adhesive may be used. In a preferred embodiment, the sideseam
adhesive is an emulsion of ethylene vinyl acetate copolymer in
water.
[0112] The cigarette wrapper may include extremely small amounts of
inks containing oils, varnishes, pigments, dyes, and processing
aids, such as solvents and antioxidants. Ink components may include
such materials as linseed varnish, linseed oil polymers, white
mineral oils, clays, silicas, natural and synthetic pigments, and
the like, as are known in the art.
[0113] Smoking Articles
[0114] The smoking articles of the preferred embodiments may have
various forms. Preferred smoking articles may be typically
rod-shaped, including, for example, cigarettes and cigars. In
addition, the smoking article may be tobacco for a pipe. For
example, the smoking article can have the form of a cigarette
having a smokable material (for example, tobacco cut filler)
wrapped in a circumscribing paper wrapping material. Exemplary
cigarettes are described in U.S. Pat. No. 4,561,454 to Guess. In a
preferred embodiment, the smoking article is a cigarette having a
smokable filter material or tobacco rod.
[0115] In another preferred embodiment, a cigarette is provided
which yields relatively low levels of "tar" per puff on average
when smoked under FTC smoking conditions (for example, an "ultra
low tar" cigarette).
[0116] In another preferred embodiment, a cigarette is provided
having a smokable filler material or tobacco rod having a
relatively low or negligible nicotine content, and a filter
element.
[0117] In another preferred embodiment, a cigarette is provided
having a smokable filler material or tobacco rod having a
relatively low TSNAs content, and a filter element.
[0118] The amount of smokable material within the tobacco rod can
vary, and can be selected as desired. Packing densities for tobacco
rods of cigarettes are typically between about 150 and about 300
mg/cm.sup.3, and are preferably between about 200 and about 280
mg/cm.sup.3, however, higher or lower amounts may be preferred for
certain embodiments.
[0119] Typically, a tipping material circumscribes the filter
element and an adjacent region of the smokable rod such that the
tipping material extends about 3 mm to about 6 mm along the length
of the smokable rod. Typically, the tipping material is a
conventional paper tipping material. Different tipping materials
having different porosities may be preferred. For example, the
tipping material can be essentially air impermeable, air permeable,
or can be treated (for example, by mechanical or other perforation
techniques) so as to have a region of perforations, openings or
vents, thereby providing a means for providing air dilution to the
cigarette. The total surface area of the perforations and the
positioning of the perforations along the periphery of the
cigarette can be varied in order to control the performance
characteristics of the cigarette.
[0120] The mainstream cigarette smoke may be diluted with air from
the atmosphere via the natural porosity of the cigarette wrapper
and/or tipping material, or via perforations, openings, or vents in
the cigarette wrapper and/or tipping material. Air dilution means
may be positioned along the length of the cigarette, typically at a
point along the filter element which is at a maximum distance from
the extreme mouth-end thereof. The maximum distance is dictated by
factors such as manufacturing constraints associated with the type
of tipping material employed and the cigarette manufacturing
apparatus and process. For example, for a filter element having a
27 mm length, the maximum distance may be between about 23 mm and
about 26 mm from the extreme mouth-end of the filter element. In a
preferred aspect, the air dilution means is positioned toward the
extreme mouth-end of the cigarette relative to the smoke-altering
filter segment. For example, for a filter element having a 27 mm
length including a smoke-altering filter segment of 12 mm length
and a mouth-end segment of 15 mm, a ring of air dilution
perforations can be positioned either 13 mm or 15 mm from the
extreme mouth-end of the filter element.
[0121] As used herein, the term "air dilution" is the ratio
(generally expressed as a percentage) of the volume of air drawn
through the air dilution means to the total volume of air and smoke
drawn through the cigarette and exiting the extreme mouth-end
portion of the cigarette. For air diluted or ventilated cigarettes,
the amount of air dilution can vary. Generally, the amount of air
dilution for an air-diluted cigarette is greater than about 10
percent, typically greater than about 20 percent, and often greater
than about 30 percent. Typically, for cigarettes of relatively
small circumference (namely, about 21 mm or less) the air dilution
can be somewhat less than that of cigarettes of larger
circumference. The upper limit of air dilution for a cigarette
typically is less than about 85 percent, more frequently less than
about 75 percent. Certain relatively high air diluted cigarettes
have air dilution amounts of about 50 to about 75 percent, often
about 55 to about 70 percent.
[0122] Cigarettes of certain embodiments may yield less than about
0.9, often less than about 0.5, and usually between about 0.05 and
about 0.3 FTC "tar" per puff on average when smoked under FTC
smoking conditions (FTC smoking conditions include 35 ml puffs of 2
second duration separated by 58 seconds of smolder). Such
cigarettes are "ultra low tar" cigarettes which yield less than
about 7 mg FTC "tar" per cigarette. Typically, such cigarettes
yield less than about 9 puffs, and often about 6 to about 8 puffs,
when smoked under FTC smoking conditions. While "ultra low tar"
cigarettes are generally preferred, in certain embodiments,
however, cigarettes providing less than about 0.05 or more than
about 0.9 FTC "tar" per puff are contemplated.
[0123] In certain embodiments, cigarettes yielding a low or
negligible amount of nicotine are provided. Such cigarettes
generally yield less than about 0.1, often less than about 0.05,
frequently less than about 0.01, and even less than about 0.005 FTC
nicotine per puff on average when smoked under FTC smoking
conditions. In other embodiments, a cigarette delivering higher
levels of nicotine may be desired. Such cigarettes may deliver
about 0.1, 0.2, 0.3, or more FTC nicotine per puff on average when
smoked under FTC smoking conditions.
[0124] Cigarettes yielding a low or negligible amount of nicotine
may yield between about 1 mg and about 20 mg, often about 2 mg to
about 15 mg FTC "tar" per cigarette; and may have relatively high
FTC "tar" to FTC nicotine ratios of between about 20 and about
150.
[0125] Cigarettes of the preferred embodiments may exhibit a
desirably high resistance to draw, for example, a pressure drop of
between about 50 and about 200 mm water pressure at 17.5 cc/sec of
air flow. Typically, pressure drop values of cigarettes are
measured using instrumentation available from Cerulean (formerly
Filtrona Instruments and Automation) of Milton Keynes, United
Kingdom. Cigarettes of preferred embodiments preferably exhibit
resistance to draw values of about 70 to about 180, more preferably
about 80 to about 150 mm water pressure drop at 17.5 cc/sec of
airflow.
[0126] Cigarettes of preferred embodiments may include a
smoke-altering filter segment. The smoke-altering filter segment
may reduce one or more undesirable components in the smoke, and/or
may provide an enhanced tobacco smoke flavor, a richer smoking
character, enhanced mouthfeel and increased smoking satisfaction,
as well as improvement of the perceived draw characteristics of the
cigarette.
[0127] Catalyst System for Reducing Carcinogens in Smoke
[0128] In preferred embodiments, smoking articles incorporating the
cooling compounds of preferred embodiments also incorporate a
catalyst system including catalytic metallic and/or carbonaceous
particles and a nitrate or nitrite source. The catalyst system is
incorporated into the smokable material so as to reduce the
concentration of certain undesirable components in the resulting
smoke. In embodiments wherein the particles are metallic, the
particles are preferably prepared by heating an aqueous solution of
a metal ion source and a reducing agent, preferably a reducing
sugar or a metal ion source, with hydroxide. Preferably, after the
metallic particles are formed in solution, the nitrate or nitrite
source is added to the solution, and the solution is applied to the
smokable material. However, embodiments in which the particles and
the nitrate or nitrite source are added separately to the smokable
material are also contemplated. The catalyst system and smoking
articles incorporating the same are described in detail in
copending U.S. application Ser. No. 10/007,724 filed on Nov. 9,
2001 and entitled "METHOD AND PRODUCT FOR REMOVING CARCINOGENS FROM
TOBACCO SMOKE."
[0129] Metallic Particles
[0130] In preferred embodiments, particles of a catalytic metallic
substance are applied to the smokable materials. The term
"metallic", as used herein, is a broad term and is used in its
ordinary sense, including without limitation, pure metals, mixtures
of two or more metals, mixtures of metals and non-metals, metal
oxides, metal alloys, mixtures or combinations of any of the
aforementioned materials, and other substances containing at least
one metal. Suitable catalytic metals include the transition metals,
metals in the main group, and their oxides. Many metals are
effective in this process, but preferred metals include, for
example, Pd, Pt, Rh, Ag, Au, Ni, Co, and Cu.
[0131] Many transition and main group metal oxides are effective,
but preferred metal oxides include, for example, AgO, ZnO, and
Fe.sub.2O.sub.3. Zinc oxide and iron oxide are particularly
preferred based on physical characteristics, cost, and carcinogenic
behavior of the oxide. A single metal or metal oxide may be
preferred, or a combination of two or more metals or metal oxides
may be preferred. The combination may include a mixture of
particles each having different metal or metal oxide compositions.
Alternatively, the particles themselves may contain more than one
metal or metal oxide. Suitable particles may include alloys of two
or more different kinds of metals, or mixtures or alloys of metals
and nonmetals. Suitable particles may also include particles having
a metal core with a layer of the corresponding metal oxide making
up the surface of the particle. The metallic particles may also
include metal or metal oxide particles on a suitable support
material, for example, a silica or alumina support. Alternatively,
the metallic particles may include particles including a core of
support material substantially encompassed by a layer of
catalytically active metal or metal oxide. In addition to the
above-mentioned configurations, the metallic particles may in any
other suitable form, provided that the metallic particles have the
preferred average particle size.
[0132] The particles may be prepared by any suitable method as is
known in the art. When preparing metallic particles, suitable
methods include, but are not limited to, wire electrical explosion,
high energy ball milling, plasma methods, evaporation and
condensation methods, and the like. However, in preferred
embodiments, the particles are prepared via reduction of metal ions
in aqueous solution, as described below.
[0133] While any suitable metal, metal oxide, or carbonaceous
particle (as described below) is preferred, it is particularly
preferred to use a metal, metal oxide, or carbonaceous particle
that has a relatively low level of transfer to cigarette or other
smoke condensate produced upon combustion of the smokable material.
For example, palladium has a lower level of transfer than silver.
Also, metal oxides tend to have relatively low levels of transfer.
However, in certain embodiments it may be preferred to use a metal,
metal oxide, or carbonaceous particle having a relatively high
level of transfer to smoke condensate. In providing a compound that
effectively catalyzes the decomposition of nitrate salts, it is
also generally preferred that the metal, metal oxide, or
carbonaceous particle have a relatively low specific heat.
[0134] Carbonaceous Particles
[0135] In certain embodiments, particles of a catalytic
carbonaceous substance are applied to the smokable materials. The
term "carbonaceous", as used herein, is a broad term and is used in
its ordinary sense, including without limitation, graphitic carbon,
fullerenes, doped fullerenes, carbon nanotubes, doped carbon
nanotubes, other suitable carbon-containing substances, and
mixtures or combinations of any of the aforementioned
substances.
[0136] The carbonaceous particles may be prepared by any suitable
method as is known in the art. When preparing graphitic particles
suitable methods may include, but are not limited to, milling
techniques, and the like.
[0137] Fullerenes include, but are not limited to, buckminster
fullerene (C.sub.60), as well as C.sub.70 and higher fullerenes.
The structure of fullerenes and carbon nanotubes may permit them to
be doped with other atoms, for example, metals such as the alkali
metals, including potassium, rubidium, and cesium. These other
atoms may be included within the carbon cage or carbon nanotube, as
is observed for certain atoms when enclosed within endohedral
fullerene. Atoms may also be incorporated into a crystal structure,
e.g., the bct structure of A4C60 (wherein A=K,Rb,Cs, and
C=buckminster fullerene) or the bcc structure of A6C60 (wherein
A=K,Rb,Cs, and C=buckminster fullerene). Fullerenes may also be
dimerized or polymerized. Certain fullerenes, such as C.sub.70
fullerenes, are known radical traps and as such may be suitable for
use in a catalyst system without the presence of nitrate or other
radical trap generators.
[0138] Fullerenes are preferably prepared by condensing gaseous
carbon in an inert gas. The gaseous carbon is obtained, for
example, by directing an intense pulse of laser at a graphite
surface. The released carbon atoms are mixed with a stream of
helium gas, where they combine to form clusters of carbon atoms.
The gas containing clusters is then led into a vacuum chamber where
it expands and is cooled to a few degrees above absolute zero. The
clusters are then extracted. Other suitable methods for preparing
fullerenes as are known in the art may also be used.
[0139] Carbon nanotubes may be prepared by electric arc discharge
between two graphite electrodes. In the electric arc discharge
method, material evaporates from one electrode and deposits on the
other in the form of nanoparticles and nanotubes. Purification is
achieved by competitive oxidation in either the gas or liquid
phase. Carbon nanotubes may also be catalytically grown. In
catalytic methods, filaments containing carbon nanotubes are grown
on metal surfaces exposed to hydrocarbon gas at temperatures
typically between 500-1100.degree. C. Other techniques for forming
carbon nanotubes include laser evaporation techniques, similar to
those used to form fullerenes. However, any suitable method for
forming carbon nanotubes may be used.
[0140] Particle Size
[0141] The particles of preferred embodiments preferably have an
average particle size of greater than about 0.5 micron (0.5 .mu.m),
more preferably greater than about 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2,
1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2 .mu.m. The preferred size
may depend on the metallic or carbonaceous substance. Particle
sizes can be as large as 150 .mu.m or more, more preferably 150,
140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30, 20, 19, 18,
17, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3 .mu.m or less in
diameter. In other embodiments, preferred particle size may be less
than or equal to about 0.5 .mu.m (500 nm), or 400, 300, 200, 100,
90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 nm or
less. In preferred embodiments, the particles are of a
substantially uniform size distribution, that is, a majority of the
metallic particles present have a diameter generally within about
.+-.50% or less of the average diameter, preferably within about
.+-.45%, 40%, 35%, 30% or less of the average diameter, more
preferably within .+-.25% or less of the average diameter, and most
preferably within .+-.20% or less of the average diameter. The term
"average" includes both the mean and the mode.
[0142] While a uniform size distribution may be generally
preferred, individual particles having diameters above or below the
preferred range may be present, and may even constitute the
majority of the particles present, provided that a substantial
amount of particles having diameters in the preferred range are
present. In other embodiments, it may be desirable that the
particles constitute a mixture of two or more particle size
distributions, for example, a portion of the mixture may include a
distribution on nanometer-sized particles, and a portion of the
mixture may include a distribution of micron-sized particles. The
particles of preferred embodiments may have different forms. For
example, a particle may constitute a single, integrated particle
not adhered to or physically or chemically attached to another
particle. Alternatively, a particle may constitute two or more
agglomerated or clustered smaller particles that are held together
by physical or chemical attractions or bonds to form a single
larger particle. The particles may have different atomic level
structures, including but not limited to, for example, crystalline,
amorphous, and combinations thereof. In various embodiments, it may
be desirable to include different combinations of particles having
various properties, including, but not limited to, particle size,
shape or structure, chemical composition, crystallinity, and the
like.
[0143] Nitrate or Nitrite Source
[0144] Any suitable source of nitrate or nitrite may be preferred.
Preferred nitrate or nitrite sources include the nitrate or nitrite
salts, of metals selected from Groups Ia, Ib, Ia, IIb, IIIa, IIIb,
IVa, IVb, Va, Vb, and the transition metals of the Periodic Table
of Elements.
[0145] In preferred embodiments, the nitrate or nitrite source
includes a nitrate of lithium, sodium, potassium, rubidium, cesium,
magnesium, calcium, strontium, yttrium, 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. Preferably, the nitrate salt may be an alkali or
alkaline earth metal nitrate. More preferably, the nitrate or
nitrite source may be selected from the group of calcium,
magnesium, and zinc with magnesium nitrate being the most preferred
salt. In a particularly preferred embodiment,
Mg(NO.sub.3).sub.2-6H.sub.2O may be preferred as a nitrate source.
While nitrate and nitrite salts are generally preferred, any
suitable metal salt or organometallic compound, or other compound
capable of releasing nitric oxide may be preferred.
[0146] While not wishing to be limited to any particular mechanism,
it is believed that the nitrate or nitrite source forms nitric
oxide radicals and that this reaction process is catalyzed by the
metallic or carbonaceous particles in the combustion zone of
tobacco. The nitric oxide radicals are believed to act as a trap
for other organic radicals that are responsible for formation of
PAHs and other carcinogenic compounds.
[0147] The temperature at which a particular nitrate or nitrite
source decomposes to form nitric oxide may vary. Since a
temperature gradient exists across the combustion zone of a tobacco
rod, the choice and concentration of the nitrate or nitrite source
may be selected so as to provide optimum production of nitric oxide
during combustion. Certain nitrates and nitrites alone, especially
those of the Group Ia metals, function as effective combustion
promoters, accelerating the burn rate of the smokable material and
decreasing the total smoke yield, but not necessarily decreasing
the quantity of PAHs within the smoke. The nitric oxide yield of
such nitrates may also be relatively low.
[0148] In certain embodiments, it may be preferred that the metal
ion source and the nitrate or nitrite source constitute the same
compound, for example, palladium(II) nitrate.
[0149] Catalyst Preparation
[0150] In preferred embodiments, metallic particles may be prepared
from an aqueous solution. For example, metal particles may be
prepared from an ion source containing one or more metal ion
sources and one or more reducing sugars. Suitable metal ion sources
include any ionic or organometallic compound that is soluble in
aqueous solution and is capable of yielding metal ions that may be
reduced to particles of a catalytic metal or utilized to form a
metal oxide. In a particularly preferred embodiment, the catalytic
source includes a metal such as palladium, and the palladium ion
source includes water-soluble palladium salts. Illustrative
non-limiting examples of suitable palladium salts include simple
salts such as palladium nitrate, palladium halides such as
palladium di or tetrachloride diammine complexes such as
dichlorodiamminepalladium(II) (Pd(NH.sub.3).sub.2Cl.sub.2), and
palladate salts, especially ammonium salts such as ammonium
tetrachloropalladate(II- ) and ammonium
hexachloropalladate(IV).
[0151] One form of palladium that may be especially preferred is
ammonium tetrachloropalladate(II), (NH.sub.4).sub.2PdCl.sub.4.
Ammonium tetrachloropalladate is generally preferred over ammonium
hexachloropalladate because under typical conditions for preparing
the metallic particles, a higher metal ion to metal conversion may
be observed for ammonium tetrachloropalladate(II).
[0152] In a preferred embodiment, an aqueous solution of reducing
agent is prepared, to which the metal ion source is added. In
preferred embodiments, the reducing agent may be a reducing sugar,
however other suitable reducing agents may be preferred. Although
any compound capable of reducing the metal ion can be employed, as
a practical matter the reducing agent is preferably non-toxic and
preferably does not form toxic byproducts when pyrolyzed during
smoking. In addition, the reducing agent is preferably
water-soluble.
[0153] Preferred reducing agents are the reducing sugars. Suitable
reducing agents include organic aldehydes, specifically
hydroxyl-containing aldehydes such as the sugars glucose, mannose,
galactose, xylose, ribose, and arabinose. Other sugars containing
hemiacetal or keto groupings may be employed, for example, maltose,
sucrose, lactose, fructose, and sorbose. Pure sugars may be
employed, but crude sugars and syrups such as honey, corn syrup,
invert syrup or sugar, and the like may also be employed. Other
reducing agents include alcohols, preferably polyhydric alcohols
such as glycerol, sorbitol, glycols, especially ethylene glycol and
propylene glycol, and polyglycols such as polyethylene and
polypropylene glycols. In alternative embodiments, other reducing
agents may be preferred, such as carbon monoxide, hydrogen, or
ethylene.
[0154] The solution is preferably heated before the metal ion
source is added to the solution, and maintained at an elevated
temperature afterwards so as to reduce the time for conversion of
the metal ions to metallic particles. In a preferred embodiment, a
reducing sugar such as low invert sugar may be preferred as the
reducing agent. In certain embodiments, it may be desirable to have
an excess or deficiency of reducing agent present in solution.
Generally, it is preferred to prepare an aqueous solution
containing from about 5 wt. % to about 20 wt. % of the reducing
sugar, preferably about 6 wt. % to about 16 or 17 wt. %, more
preferably from about 7, 8, 9, 10, or 11 wt. % to about 12, 13, 14,
or 15 wt. %. When the reducing agent is invert sugar, it is
preferred to prepare an 11 wt. % to about 12 wt. % solution. The
amount of reducing agent preferred may vary depending on the type
of reducing agent preferred and the amount of metal ion source to
be added to the solution.
[0155] It may be preferred to prepare the solution in a glass-lined
vessel equipped with a heating jacket. In certain embodiments,
however, it may be preferred to prepare the solution in another
kind of vessel constructed of or lined with another type of
material, for example, plastic, stainless steel, ceramic, and the
like. It is generally preferred to conduct the reaction in a closed
vessel. In certain embodiments, it may be desirable to conduct the
reaction under reduced pressure or elevated pressure, or under an
inert atmosphere, such as nitrogen or argon.
[0156] In preparing the aqueous solution of the reducing sugar, it
is preferred to use deionized ultrafiltered water. While in
preferred embodiments the metallic particles are prepared from
aqueous solution, in other embodiments it may be desirable to use
another suitable solvent system, for example, a polar solvent such
as ethanol, or a mixture of ethanol and water. Additional
components may be present in the solution as well, provided that
they do not substantially adversely impact the catalytic activity
of the metallic particles.
[0157] After adding the reducing sugar to the deionized
ultrafiltered water, the solution is preferably heated with
constant mixing so as to avoid hot spots in the solution. Although
in certain embodiments it may be desirable to prepare the particles
from a room temperature solution, or even a solution cooled below
room temperature, it is generally preferred to heat the solution so
as to speed the reaction between the reducing sugar and the metal
ion source once it is added to the solution. The solution may be
heated to any suitable temperature, but boiling of the solution and
decomposition of the reducing sugar is preferably avoided. In a
preferred embodiment wherein low invert sugar is the reducing
sugar, the solution is typically heated up to about 95.degree. C.
or more, preferably from above room temperature to about 90.degree.
C., more preferably from about 50.degree. C., 55.degree. C.,
60.degree. C., or 65.degree. C. 85.degree. C., and most preferably
from about 70.degree. C. or 75.degree. C. to about 80.degree.
C.
[0158] The metal ion source is added to the heated aqueous solution
of reducing agent, which is stirred while the metal ions react with
the reducing sugar to produce metallic particles. It is generally
preferred to add sufficient metal ion source so as to produce a
solution containing from less than about 3000 ppm to more than
about 5000 ppm metal. Preferably, sufficient metal ion source is
added to produce a solution containing from about 3250, 3500, or
3750 ppm to about 4250, 4500, 4750 ppm metal, more preferably from
about 3800, 3850, 3900, or 3950 ppm to about 4050, 4100, 4150, or
4200 ppm metal, and most preferably about 4000 ppm metal.
[0159] The reaction time for conversion of metal ion to metal
particles may vary depending upon the reducing agent and metal ion
source preferred, but generally ranges from about 30 minutes or
less to about 24 hours or more, and typically ranges from about 1
or 2 hours up to about 3, 4, or 5 hours. In a preferred embodiment,
wherein ammonium tetrachloropalladate is the metal ion source, a
substantial conversion of palladium ion to palladium metal may be
achieved after 3 hours for a solution heated to a temperature of
about 75.degree. C. Although in certain embodiments a lower
conversion may be acceptable, it is generally desirable to achieve
a conversion of metal ion to metal of at least 50%, preferably at
least 60%, more preferably at least 70%, and most preferably at
least 75, 80, 85% or more.
[0160] The metallic particles produced in this manner generally
have diameters of about 1 .mu.m or less. In certain other
embodiments metallic particles having individual diameters and
average diameters below about 20 nm or above about 1 .mu.m may be
produced. The size of the metallic particles may be conveniently
determined using conventional methods of X-ray diffraction or other
particle size determination methods, for example, laser
scattering.
[0161] After a sufficient conversion of metal ion to metal or metal
oxide is achieved, and the metallic particles are formed, the
nitrate or nitrite source is added to the suspension. Any suitable
compound that yields nitrate or nitrite ion in aqueous solution may
be preferred. Preferably, the nitrate or nitrite source is an
alkali metal or alkaline earth metal nitrate or nitrite. In a
particularly preferred embodiment, the nitrate or nitrite source is
magnesium nitrate, Mg(NO.sub.3).sub.2-6H.sub.2O. It is generally
preferred to add a sufficient amount of nitrate or nitrite source
so as to produce a solution containing from less than about 70 ppm
to more than about 100 ppm nitrogen (in the form of nitrate or
nitrite). Preferably, sufficient nitrate or nitrite source is added
to produce a solution containing from about 75, 80, or 85 ppm to
about 90 or 95 ppm nitrogen, more preferably from about 80 ppm
nitrogen.
[0162] Generally, it is preferred that the suspension of metallic
particles not be excessively concentrated or dilute, so as to
facilitate efficient application of the suspension to the smokable
material.
[0163] While it is generally preferred to prepare a suspension of
particles as described above by reduction of metal ion in solution,
followed by addition of the nitrate or nitrite source, in other
embodiments it may be preferred to use a different method to
prepare the particles. If the metallic or carbonaceous particles
are not prepared in solution, the particles may be mixed with an
appropriate liquid to form a suspension. Because of their high
surface area, it may be difficult to sufficiently wet the surface
of the particles so as to form a uniform suspension. In such cases,
any suitable method may be preferred to facilitate forming the
suspension, including, but not limited to, mechanical methods such
as sonication or heating, or chemical methods such as the use of
small quantities of surfactants, provided the surfactants do not
interfere with the catalytic activity of the particles. Once the
suspension is formed, addition of the nitrate or nitrite source may
proceed as described above.
[0164] While it is generally preferred to apply the metallic or
carbonaceous particles and nitrate or nitrite source to the
smokable material in the form of a suspension, other methods of
applying the particles and nitrate or nitrite source are also
contemplated. For example, if the particles are in dry form, they
may be added to the smokable material as a powder. It may be
advantageous to moisten the smokable material with a suitable
substance, for example, water, prior to application of the powder
in order to provide better adhesion of the particles to the
smokable material.
[0165] When the carbonaceous or metallic particles are added to the
smokable material in powder form, the nitrate or nitrate source in
solid form may also be applied to the smokable material in powder
form, either in a separate step before or after the addition of the
particles, or simultaneously with the particles, for example, in
admixture with the particles. Suitable methods as are well known in
the art may be used to prepare a suitable solid form of nitrate or
nitrate source. In particularly preferred methods, the solid form
of nitrate or nitrite source is prepared by freeze drying or spray
drying methods, both of which may yield extremely small particle
sizes. It is generally preferred that the nitrate or nitrite source
be in the form of particles having an average diameter on the order
of the preferred average diameters for the particles. The nitrate
or nitrite source may also be provided as a solution applied to the
smokable material as a separate step from adding the particle
powder, preferably before adding the particle in dry form to the
smokable material.
[0166] Optimization of the Catalyst System
[0167] There are many aspects to consider when attempting to
optimize the catalyst system, the first of which is the conversion
of the palladium salt to palladium metal in the aqueous reducing
solution. This conversion requires a chemical reduction reaction in
an aqueous solution. Earlier work was directed to the conversion of
the palladium salt to palladium metal in a casing solution. It was
suggested in the patent literature that the preferred reducing
agent for this reaction in the casing solution is fructose--a known
reducing sugar. One origin of fructose in the casing solution is
from low invert sugar. In an attempt to repeat this earlier
research with casing solutions and produce a more
consistent/controllable reaction, all of the components in the
casing solution were eliminated that were considered non-essential
to the reduction reaction (e.g., propylene glycol, licorice, cocoa,
and the like), while the components thought to be essential (e.g.,
water, palladium salt and low invert sugar) were retained in the
same ratios as found in the casing solution, namely 93 g water to 1
g palladium salt to 8 g low invert sugar per pound of tobacco,
respectively. Another component that was in the original casing
solution but which is now considered non-essential to the reduction
reaction is Mg(NO.sub.3).sub.2-6H.sub.2O. This component was
present in early formulations, however nitrate analysis of the
treated tobacco verified that Mg(NO.sub.3).sub.2-6H.sub.2O
decomposes to a certain degree when mixed in aqueous solutions
containing palladium metal. It was also found through early testing
that carcinogen reduction in cigarettes was not reproducible when
the Mg(NO.sub.3).sub.2-6H.sub.2O was allowed to be in contact with
palladium metal for extended periods of time. When the
Mg(NO.sub.3).sub.2-6H.sub.2O was removed from the reacting solution
and instead added to the reacting solution prior to catalyst
application on the tobacco, consistent and reproducible carcinogen
reductions in experimental cigarettes were obtainable.
[0168] One feature of the preferred reduction reaction is the
percent conversion of palladium salt to palladium metal in the
aqueous solution containing low invert sugar as a reducing agent.
At a temperature of approximately 70-75.degree. C., the percent
conversion typically increases steadily with time and after the
first three hours of the reaction more than 60-70% of the salt has
typically been converted to the metal. Most of the palladium salt
is typically converted to metal within the first hour
(approximately 50%). Longer reaction times (for example, above
three hours) generally only increase the percent conversion
modestly. Given the task of balancing maximum conversion with an
acceptable production schedule, three hours is generally preferred
as the minimum time for this reaction to occur before application
of the catalyst solution to the tobacco.
[0169] To increase production rates and lower production costs, it
is desirable to increase the percent conversion of palladium salt
to palladium metal. An immediate benefit of increasing the percent
conversion is the capacity to use less total palladium salt in the
reaction, as an increase in percent conversion with less salt may
in fact produce equivalent amounts of palladium metal in the
reaction. This results in lower consumption of the most expensive
reagent in the reaction.
[0170] Several possibilities exist to increase the percent
conversion of this reaction. The reduction reaction is based on an
aldehyde being oxidized and releasing electrons to the Pd II
nucleus, thereby producing metallic palladium. 9
[0171] In a particularly preferred catalyst system as described
above, it is believed that the aldehyde source is the reducing
sugar fructose. In theory, any compound containing an aldehyde
functional group can reduce the palladium salt to palladium metal.
However to apply the resulting mixture to tobacco it is preferred
that the reducing agent is non-toxic. As discussed previously in
regard to the particularly preferred catalyst system, low invert
sugar is used as the "reducing agent" for this reaction and it is
believed that the fructose component of low invert sugar is the
active reducing agent. Interestingly, pure fructose when supplied
as a reducing agent for the palladium reduction has been shown not
to be very effective, even when the fructose is in 10 molar excess.
This observation suggests that there is an additional "co-reducing
agent" or possibly a catalyst for the reducing agent contained
within the low invert sugar solution. Due to the complex mixture
associated with low invert sugar it will continue to be a challenge
to discover exactly what the reducing agent or agents are when
utilizing low invert sugar as a reactant. Nevertheless, the
particularly preferred system performs remarkably well given the
fact that the mechanism for palladium reduction is not well
understood in this system.
[0172] Application of Catalyst to Smokable Material
[0173] After the nitrate or nitrite source has been added to the
suspension containing metallic or carbonaceous particles, it is
applied to the smokable material. If the smokable material is
tobacco, it is preferred to apply the suspension to cut filler
prior to addition of the top flavor. If a top flavor is not
applied, then it is preferred to apply the suspension to the cut
filler as a final step, for example, before it is formed into a
tobacco rod. The catalytic particles may be applied before, during,
or after application of a casing solution, however in a preferred
embodiment the catalytic particles are applied after application of
the casing solution. Casing solutions are pre-cutting solutions or
sauces added to tobacco and are generally made up of a variety of
ingredients, such as sugars and aromatic substances. Such casing
solutions are generally added to tobacco in relatively large
amounts, for example, one part casing solution to five parts
tobacco.
[0174] The particles and nitrate or nitrite source are preferably
well dispersed throughout the tobacco so as to provide uniform
effectiveness throughout the entire mass of smokable material and
throughout the entire period during which the material is smoked.
In the case of cigarette tobacco wherein a blend of various
tobaccos is preferred, the suspension may be applied to one or more
of the blend constituents, or all of the blend constituents, as
desired. Preferably, the suspension is applied to all of the blend
constituents so as to ensure substantially uniform coverage of the
particles and nitrate or nitrite source.
[0175] For certain types of suspensions of particles, a degradation
in performance may be observed if an excessive period of time is
allowed to elapse before the suspension is applied to the smokable
product. This degradation in performance may be due to various
factors, including loss of particles from the suspension due to
their accumulation on the interior surfaces of the reaction vessel,
or an undesirable increase in particle size over time. When the
suspension includes palladium particles, the suspension is
generally applied to the cut filler within about ten hours after
the desired degree of metal ion conversion is reached and the
nitrate or nitrite source is added to the suspension. The
suspension is preferably applied within about 9, 8, 7, or fewer
hours, more preferably within about 6, 5, or 4 hours, and most
preferably within 3, 2, or 1 hours or less. However, in certain
embodiments, including those utilizing palladium particles, it may
be possible to apply the suspension after a delay of longer than
ten hours while maintaining acceptable catalytic performance.
[0176] It is preferred to apply the suspension to the smokable
material in the form of a fine mist, such as is produced using an
atomizer. In a particularly preferred embodiment, the suspension is
applied to tobacco, preferably cut filler, in a rotating tumbler
equipped with multiple spray heads. Such a method of application
ensures an even coating of the metallic particles on the tobacco
product. The tobacco may be heated during or after application of
the solution so as to facilitate evaporation of excess solvent.
[0177] It is preferred to add a sufficient quantity of the metallic
or carbonaceous particle suspension to the smokable material such
that the smokable material contains from about 500 ppm or less to
about 1500 ppm or more of the metal or carbon in the form of
catalytic particles. Preferably, the smokable material contains
from about 500 ppm to about 1000, 1100, 1200, 1300, or 1400 ppm of
the metal or carbon in the form of catalytic particles, more
preferably 500, 600 or 700 to about 800, 900, or 1000 ppm, and most
preferably about 800 ppm. It is generally preferred that the
smokable material contains from about 0.4 to about 1.5 wt. %
nitrogen (from nitrate or nitrite). Preferably, the smokable
material contains from about 0.5 or 0.6 wt. % to about 1.0, 1.1,
1.2, 1.3, or 1.4 wt. % nitrogen, more preferably from about 0.6,
0.7, or 0.8 wt. % to about 0.9 wt. %, and most preferably about 0.9
wt. % nitrogen. In a preferred embodiment, one kilogram of tobacco
constitutes 800 milligrams of metal or carbon in the form of
catalytic particles, and 9 grams of nitrogen in the form of the
nitrate or nitrite source.
[0178] Once the metallic or carbonaceous particles and nitrate or
nitrite source have been applied, the smokable material may be
further processed and formed into any desired shape or used
loosely, for example, in cigars, cigarettes, or pipe tobacco, in
any suitable manner as is well-known to those skilled in the
art.
[0179] The above description discloses several methods and
materials of the present invention. Such modifications will become
apparent to those skilled in the art from a consideration of this
disclosure or practice of the invention disclosed herein.
Consequently, it is not intended that this invention be limited to
the specific embodiments disclosed herein, but that it cover all
modifications and alternatives coming within the true scope and
spirit of the invention as embodied in the attached claims.
* * * * *