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D E S C R I P T I 0 N
CIGARETTE FILTER AND CIGARETTE PROVIDED WITH THE SAME
Technical Field
The present invention relates to a cigarette
filter and a cigarette provided with the same, and more
specifically, to a cigarette filter excellent in
efficiency of removing nitrogen oxides (NOx) in the
mainstream smoke and a cigarette provided with the
same.
Background Art
Nowadays, various requirements are imposed on
cigarettes, one of which is to decrease the amount of
NOx in the mainstream smoke of cigarettes (Jpn. Pat.
Appln. KOKAI Publication No. 2002-119270). Jpn. Pat.
Appln. KOKAI Publication No. 2002-119270 discloses a
tobacco filter in which a procyanidin is incorporated
in filaments that form the filter.
However, it has been found that the conventional
tobacco filters are not capable of removing NOx from
the mainstream smoke to a satisfactory degree.
Disclosure of Invention
Thus, it is an object of the present invention to
provide a cigarette filter that can efficiently remove
nitrogen oxides from the tobacco mainstream smoke, and
a cigarette provided with such filter.
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According to the present invention, there
is provided a cigarette filter comprising a
cigarette filter material to which
2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-l-oxyl
is added.
Further, according to the present invention, there
is provided a cigarette provided with a cigarette
filter according to the present invention.
Brief Description of Drawings
FIG. 1 is a graph showing the reduction rate of NO
in the mainstream smoke of cigarettes manufactured in
Example 1, which will be described later in detail,
together with that of a comparative example;
FIG. 2 is a graph showing the reduction rate of NO
in the mainstream smoke of cigarettes manufactured in
Example 2, which will be described later in detail,
together with that of a comparative example;
FIG. 3 is a graph showing the reduction rate of NO
in the mainstream smoke of cigarettes manufactured in
Example 3, which will be described later in detail,
together with that of a comparative example; and
FIG. 4 is a graph showing the reduction rate of NO
in the mainstream smoke of cigarettes manufactured in
Example 4, which will be described later in detail,
together with that of a comparative example.
Best Mode for Carrying Out the Invention
The present invention will be described in more
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detail below.
A cigarette filter according to the present
invention comprises a cigarette filter material to
which 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-
1-oxyl (PTIO) is added.
In the cigarette filter of the present invention,
PTIO, an effective ingredient for removing nitrogen
oxides, is a compound known per se (see, for example,
Jpn. Pat. Appln. KOKAI Publication No. 9-43153).
In the cigarette filter of the present invention,
use may be made, as the filter material, of cellulose
acetate fiber tow, filter paper and porous particulate
carrier such as activated carbon. In the case where
cellulose acetate fiber tow is used as the filter
material, PTIO can be added by spraying PTIO onto the
fiber tow. When filter paper is used, PTIO can be
impregnated into the filter paper. The filter material
thus obtained can be wrapped with a wrapper by an
ordinary method, and connected to an end of a
cigarette.
In the case where a porous particulate carrier
such as activated carbon is used as the filter
material, PTIO is impregnated in the porous particulate
carrier, and then the thus obtained PTIO-carrying
particles are filled in a cavity as is known in the art
or added to a tow. More specifically as to the cavity
filling, a plain filter is provided to either end of a
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filter wrapper paper pipe. The PTIO-carrying particles
are filled in the cavity between these plain filters.
On the other hand, the addition to the tow is carried
out by a method similar to that used for charcoal
filters of commercially available cigarettes, that is,
the PTIO-carrying particles are dispersed between the
fibers of the acetate filter.
PTIO is added preferably in an amount of 3 to 10
parts by weight, particularly preferably, 5 to 7 parts
by weight based on 100 parts by weight of the filter
material. PTIO significantly reduces the amount of NO
and NOx contained in the cigarette mainstream smoke
even under wet conditions, which are equivalent to the
actual smoking conditions.
The present invention will be described by way of
Examples, but the present invention should not be
limited to the Examples.
Example 1
<Preparation of PTIO-impregnated activated carbon>
10 mg, 30 mg, 50 mg and 100 mg of PTIO (available
from Wako Pure Chemical Industries, Ltd.; CAS:
18390-00-6) were completely dissolved in 2490 mg,
2470 mg, 2450 mg and 2400 mg of ethanol, respectively,
thus preparing PTIO ethanol solutions having a
concentration of 0.4% by weight, 1.2% by weight, 2% by
weight and 4% by weight, respectively. To each of the
ethanol solutions, lg of coconut shell activated carbon
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(available from Japan Envirochemicals Ltd; a specific
surface area: about 1200 m2/g), which was dried in
advance by heating at 200 C in vacuo, was added, and
stirred for 60 minutes using a test tube mixer.
5 Thereafter, the solvent ethanol was removed in a water
bath of 50 C while blowing nitrogen gas into the
solution, and then the resultant material was dried by
heating at 120 C in vacuo. Thus, PTIO-impregnated
activated carbon was obtained. It was measured that
the PTIO-impregnated activated carbon obtained using
the ethanol solution having a PTIO concentration of
0.4% by weight was impregnated with PTIO in an amount
corresponding to 1% of the weight of activated carbon
(PTIO-impregnated activated carbon I), the PTIO-
impregnated activated carbon obtained using the ethanol
solution having a PTIO concentration of 1.2% by weight
was impregnated with PTIO in an amount corresponding to
3% of the weight of activated carbon (PTIO-impregnated
activated carbon II), the PTIO-impregnated activated
carbon obtained using the ethanol solution having a
PTIO concentration of 2% by weight was impregnated with
PTIO in an amount corresponding to 5% of the weight of
activated carbon (PTIO-impregnated activated carbon
III), and the PTIO-impregnated activated carbon
obtained using the ethanol solution having a PTIO
concentration of 4% by weight was impregnated with PTIO
in an amount corresponding to 10% of the weight of
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activated carbon (PTIO-impregnated activated carbon
IV).
<Manufacture of Cigarette Samples>
Commercially available American blend tobacco rods
were used as tobacco rods. Filter plugs in which PTIO-
impregnated activated carbons obtained above were
cavity-filled were attached to one-end sides of the
tobacco rods respectively. The filter plugs had a
plain filter (made of cellulose acetate fiber tow)
having a length of 5 mm provided on both ends of each
plug and 0 mg, 50 mg, 100 mg and 200 mg of PTIO-
impregnated activated carbon particles were filled at
closest packing. The plugs had no ventilation holes.
<Measurements of Amount of NO and NOx>
The cigarette samples obtained above were set on a
smoking machine (RM 26 available from Borgwaldt GmbH),
and were burnt under the following conditions.
Smoke suction volume: 17.5 mL/puff
Puffing time: 2 seconds/puff
Puff interval: 58 seconds
Number of times of puffing: 7 times
For each of 7 times of puffing (smoke suction) and
an idle running puff (one time after completion of
burning), smoke having passed though the Cambridge
filter was diluted 20-fold (by collecting it with an
aluminum bag in which 17.5 mL x 19 = 332.5 mL of
nitrogen gas was injected in advance). Then, the
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concentrations of NO and NOx were measured by the
chemiluminescent method. The weights of NO and NOx
were calculated from the concentrations obtained above,
and the calculated weight values of all the puffs and
idle-running puff were summed up to obtain a delivery
amount per cigarette. For comparison purpose, a
similar cigarette sample was manufactured with
activated carbon not impregnated with PTIO, and the
delivery amount per cigarette was obtained in a similar
manner. The NO and NOx reduction rates were calculated
based on the NO and NOx delivery amounts per cigarette
obtained similarly for a plain cigarette without the
filter connected thereto. The NO reduction rate (o) of
each sample was illustrated in FIG. 1. In FIG. 1, a
line indicates the results obtained in the case where
the PTIO-impregnated activated carbon I was used, a
line b indicates the results obtained in the case where
the PTIO-impregnated activated carbon II was used, a
line c indicates the results obtained in the case where
the PTIO-impregnated activated carbon III was used, a
line d indicates the results obtained in the case where
the PTIO-impregnated activated carbon IV was used, and
a line e indicates the results obtained in the case
where the activated carbon with no PTIO impregnated was
used.
From the results shown in FIG. 1, it can be seen
that the filters that contain PTIO-impregnated
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activated carbon particles significantly reduce the
amount of NO as compared to the activated carbon
particles that do not contain PTIO. In particular, the
activated carbons carrying 3 to 10% by weight of PTIO
have a remarkably high NO reduction effect. It should
be noted that the NOx reduction rate exhibited a
tendency similar to those of the above-described NO
reduction rates.
Example 2
PTIO-impregnated activated carbon II prepared in
Example 1 was subjected to moisture absorption until it
reaches the equilibrium at a temperature of 22 C and a
relative humidity of 60%, and thus moisture-absorbed
PTIO-impregnated activated carbon III was obtained.
Cigarettes were manufactured as in Example 1 except
that the moisture-absorbed PTIO-impregnated activated
carbon III was used, and the NO reduction rate in the
mainstream smoke was obtained. The results were
illustrated in FIG. 2. In FIG. 2, a line a indicates
the results obtained in the case where the moisture-
absorbed PTIO-impregnated activated carbon III was
used, and a line b indicates the results obtained in
the case where activated carbon obtained by similar
moisture absorption except that PTIO was not
impregnated. From the results shown in FIG. 2, it can
be seen that when the moisture absorption is carried
out, the NO reduction rate is slightly lowered as
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compared to the case of the dry PTIO-impregnated
activated carbon III (Example 1); however the NO amount
is significantly reduced as compared to the case where
simple activated carbon is used, indicating that PTIO
will sufficiently have an effect of reducing the NO
amount, even under actual smoking (corresponding to
filter ventilation of 500). It should be noted also
here that the NOx reduction rate exhibited a tendency
similar to that of the NO reduction rate described
above.
Example 3
The cigarette samples manufactured in Example 1
were burnt under the same conditions as in Example 1
except that the smoke suction volume was changed to
35 mL/puff. Cigarette samples using activated carbon
not impregnated with PTIO were burnt also at a smoke
suction volume of 35 mL/puff. The NO reduction rate in
the mainstream smoke was calculated. The results are
illustrated in FIG. 3. In FIG. 3, a line a indicates
the results obtained in the case where the PTIO-
impregnated activated carbon III was used, and a line b
indicates the results obtained in the case where the
activated carbon without PTIO was used. From the
results shown in FIG. 3, it can be seen that when the
smoke suction volume is increased, the NO reduction
rate is lowered as compared to the case of Example 1;
however the samples using the PTIO-impregnated
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activated carbon III exhibits a significantly higher NO
reduction rate than that of the cigarette samples using
the activated carbon without PTIO. It should be noted
also here that the NOx reduction rate exhibited a
5 tendency similar to that of the NO reduction rate
described above.
Example 4
Cigarette samples similar to those of Example 2
(which used moisture-absorbed PTIO) were burnt under
10 the same conditions as those in Example 3, and the NO
reduction rate in the mainstream smoke was calculated.
With regard to cigarette samples using activated carbon
not impregnated with PTIO, the NO reduction rate in the
mainstream smoke was calculated. The results were
illustrated in FIG. 4. In FIG. 4, a line a indicates
the results obtained in the case where the PTIO-
impregnated activated carbon was used, and a line b
indicates the results obtained in the case where the
activated carbon without PTIO was used. From the
results shown in FIG. 4, it can be seen that when the
smoke suction volume is increased, the NO reduction
rate is lowered as compared to the case of Example 2;
however the samples using the PTIO-impregnated
activated carbon exhibits a significantly higher NO
reduction rate than that of the cigarette samples using
the activated carbon without PTIO. It should be noted
also here that the NOx reduction rate exhibited a
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tendency similar to that of the NO reduction rate
described above.
As described above, the cigarette filter of the
present invention can efficiently remove nitrogen
oxides from the tobacco mainstream smoke.
