Note: Descriptions are shown in the official language in which they were submitted.
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D E S C R I P T I O N
CIGARETTE FILTER AND FILTER-TIPPED CIGARETTE
Technical Field
The present invention relates to a cigarette
filter and a filter-tipped cigarette.
Background Art
Filter-tipped cigarettes are developed and
marketed to, for example, milden the smoking taste.
The filter-tipped cigarette comprise a cigarette main
body formed of a tobacco filler rod, such as one
comprising cut tobacco having the circumference thereof
wrapped with a cigarette paper, and a filter fitted to
one end of the cigarette main body. The filter has at
least one filter plug. In the filter plug, a filter
material is disposed in a cylindrical body formed of a
wrapper (filter plug wrapper) shaped into a cylindrical
configuration (generally the configuration of a
circular cylinder). The filter is fitted to one end of
the cigarette main body by means of a tipping paper.
The filter hardness of the filter-tipped cigarette
is a parameter for the choice of cigarette by smokers.
Most of now commercially available filter-tipped
cigarettes use a cellulose acetate fiber bundle (tow)
as a filter material (hereinafter also referred to as
cellulose acetate filter). As satisfactory filter
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hardness cannot be obtained by the cellulose acetate
fiber alone, a plasticizer (for example, triacetin) is
mixed therein so as to impart hardness to the filter.
It is known that the amount of triacetin added to the
cellulose acetate filter of now commercially available
filter-tipped cigarettes is in the range of 5 to 10% by
weight based on the amount of cellulose acetate.
Some smokers are satisfied with the current filter
hardness imparted by the addition of the above amount
of triacetin, but some smokers like harder filters.
It is known that with respect to the cellulose
acetate filter, the hardness thereof can be increased
by increasing the amount of plasticizer added.
However, when the amount of triacetin added is
increased to a certain extent or over, the triacetin is
hydrolyzed to thereby generate acetic acid. Thus,
there would occur the problem that the interior of the
cigarette package is filled with the odor of acetic
acid. Further, when a charcoal filter is employed,
there would occur the problem that triacetin is
adsorbed on the charcoal with the result that the
function of the charcoal (adsorption of smoke
components) cannot be fully exerted.
With respect to the filter-tipped cigarettes, it
is desired for the ventilation ratio thereof to be high
in order to permit the inflow of ambient air for higher
dilution of mainstream smoke.
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A cigarette filter of high ventilation ratio,
known as a recessed cigarette filter, is disclosed in
the pamphlet of International Publication WO 00/00047.
This cigarette filter comprises, for example, two
filter plugs both wrapped with a porous or nonporous
filter plug wrapper, the two filter plugs joined to
each other by means of a nonporous shaping paper. This
filter is fitted to a tobacco rod by means of a tipping
paper. In order to achieve a high ventilation ratio,
the filter plug wrapper and the shaping paper are
provided with mechanically perforated relatively large
ventilation holes, and the tipping paper is provided
with a relatively small ventilation hole perforated by
laser. The ventilation holes would cause such problems
that.the cigarette manufacturing cost is increased, the
versatility to a variety of cigarette products,
including a low-tar cigarette or the like, is lowered,
and the stability of product quality is poor. These
problems are also pointed out for Jpn. PCT National
Publication No. 2004-516814 disclosing a similar
recessed filter.
In the pamphlet of International Publication WO
00/00047 and Jpn. PCT National Publication No. 2004-
516814, there is no direct mention of the filter
hardness.
Disclosure of Invention
It is an object of the present invention to
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provide a cigarette filter that can achieve
satisfactory hardness and ventilation ratio even when
the filter plug wrapper and shaping paper are not
furnished with any ventilation hole and even when any
hardness increasing agent is not used therein, and to
provide a cigarette comprising such a cigarette filter.
According to a first aspect of the present
invention, there is provided a cigarette filter
comprising: a filter plug comprising a cylindrical body
of a filter plug wrapper which is cylindrically shaped
and a filter material disposed in the cylindrical body,
characterized in that the filter plug wrapper is formed
of a high-rigidity and high-permeability paper; wherein
longitudinal rigidity is 30 cm3/l00 or higher, as
measured in accordance with JIS P8143 and air
permeability is 1000 CORESTA units or greater.
According to a second aspect of the present
invention, there is provided a cigarette filter
comprising: a plurality of filter plugs comprising a
most upstream filter plug and a most downstream filter
plug, each comprising a cylindrical body of a filter
plug wrapper which is cylindrically shaped and a filter
material disposed in the cylindrical body, and a
shaping paper configured to wrap the circumference of
the plurality of filter plugs and join the plurality of
filter plugs to each other, characterized in that the
filter plug wrapper of at least one of the plurality of
CA 02708837 2012-03-27
filter plugs is formed of a high-rigidity and high-
permeability paper, wherein a longitudinal rigidity is
30 cm3/100 or higher, as measured in accordance with JIS P8143
and an air permeability is 1000 CORESTA units or greater.
According to a third aspect of the present
invention, there is provided a cigarette filter
comprising a plurality of filter plugs comprising a
most upstream filter plug and a most downstream filter
plug, each comprising a cylindrical body of filter plug
wrapper which is cylindrically shaped, a filter
material disposed in the cylindrical body, and a
shaping paper configured to wrap the circumference of
the plurality of filter plugs and join the plurality of
filter plugs to each other, characterized in that the
shaping paper is formed of a high-rigidity and high-
permeability paper, wherein a longitudinal rigidity is
30 cm3/100 or higher, as measured in accordance with JIS P8143
and an air permeability is 1000 CORESTA units or greater.
Further, according to a fourth aspect of the
present invention, there is provided a filter-tipped
cigarette comprising a cigarette main body comprising a
tobacco rod wrapped with a cigarette paper and a
cigarette filter fitted to one end of the cigarette
main body, characterized in that the cigarette filter
is formed of the cigarette filter of the present
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invention.
Brief Description of Drawings
FIG. 1 is a partially developed schematic
perspective view of a filter-tipped cigarette provided
with a single-segment filter according to an embodiment
of the present invention.
FIG. 2 is a partially developed schematic
perspective view of a filter-tipped cigarette provided
with a multisegment filter according to an embodiment
of the present invention.
FIG. 3 is a partially developed schematic
perspective view of a filter-tipped cigarette provided
with a recessed single-segment filter according to an
embodiment of the present invention.
FIG. 4 is a graph showing the hardness of each of
cellulose acetate filter plugs according to embodiments
of the present invention together with that of the
conventional cellulose acetate filter plug.
FIG. 5 is a graph showing changes of the hardness
of a cellulose acetate filter plug according to an
embodiment of the present invention together with that
of the conventional cellulose acetate filter plug
brought about by changing the amount of triacetin
added.
FIG. 6 is a graph showing the hardness of each of
paper filter plugs according to embodiments of the
present invention together with that of the
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conventional paper filter plug.
FIG. 7 is a graph showing changes with time of the
menthol existence ratios in the cut tobacco and filter
material with respect to a cellulose acetate filter.
FIG. 8 is a graph showing changes with time of the
menthol existence ratios in the cut tobacco and filter
material with respect to a paper filter.
FIG. 9 is a graph showing changes with time of
menthol delivery into cigarette mainstream smoke with
respect to each of a cigarette with a cellulose acetate
filter and a cigarette with a paper filter.
Best Mode for Carrying Out the Invention
The cigarette filter of the present invention
encompasses a so-called single-segment filter formed of
a single filter plug and a so-called multisegment
filter comprising a plurality of filter plugs including
a most upstream filter plug and a most downstream
filter plug. In either case, each of the filter plugs
includes a cylindrical body, generally in the form of a
circular cylinder, of filter plug wrapper which is
cylindrically shaped and a filter material disposed in
the cylindrical body. Illustratively, the filter plug
includes a filter material rolled up (wrapped) with a
filter plug wrapper. In the multisegment filter, the
plurality of filter plugs are wrapped with a shaping
paper so as to be joined to each other. In the present
invention, the expressions "upstream" and "downstream"
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are based on the direction of flow of tobacco
mainstream smoke passing through the interior of a
cigarette.
In the present invention, the filter plug wrapper
of the single-segment filter is formed of a specified
high-rigidity and high-permeability paper. Also, in
the multisegment filter of the present invention, the
filter plug wrapper of at least one filter plug and/or
the shaping paper is formed of a specified high-
rigidity and high-permeability paper.
The high-rigidity and high-permeability paper for
use in the present invention has a longitudinal
rigidity (stiffness in the longitudinal direction) of
paper of 30 or higher as measured in accordance with
JIS P8143 (method of testing the stiffness of paper by
self-weight bending) and an air permeability of 1000
CORESTA units or greater. Preferably, the high-
rigidity and high-permeability paper has a longitudinal
rigidity of 30 to 400 and an air permeability of 1000
to 30,000 CORESTA units.
Examples of high-rigidity and high-permeability
papers for use in the present invention (represented by
symbols Si to S4) are given in Table 1. Table 1 also
includes a now generally employed porous filter plug
wrapper of high air permeability (conventional filter
plug wrapper, represented by symbol P).
CA 02708837 2010-06-10
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CA 02708837 2010-06-10
The case where cellulose acetate fiber tow is used
as a filter material will be described. As
aforementioned, it is of common practice to add a
plasticizer, such as triacetin, to a filter in an
5 amount corresponding to 5 to 10% by weight based on the
weight of cellulose acetate fiber in order to impart a
given hardness to the filter. However, when the high-
rigidity and high-permeability paper according to the
present invention is employed, the same filter hardness
10 as heretofore can be achieved even by the addition of
plasticizer in an amount corresponding to less than 5%
(including 0%) based on the weight of cellulose acetate
fiber. Needless to state, when the plasticizer is
added to the cellulose acetate fiber in the same amount
corresponding to 5 to 10% based on the weight thereof
as heretofore, the hardness over the conventional
filter can be achieved.
From the finding to now, it is understood that the
addition of triacetin in an amount of over 12% by
weight will dissolve the cellulose acetate fiber and
will invite the problem of the occurrence of acetic
acid odor attributed to the decomposition of triacetin.
Accordingly, the upper-limit value of the conventional
filter hardness achieved without the occurrence of
these problems is the hardness corresponding to the
addition of 12% by weight triacetin. However, when the
high-rigidity and high-permeability paper according to
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the present invention is employed, the addition of 12%
by weight triacetin can achieve hardness over the
conventional upper-limit value. That is, the present
invention can be applied to the cellulose acetate
filter having triacetin added in an amount of over 10%
by weight but not exceeding 12% by weight.
The filter material of the cigarette filter of the
present invention is not limited to a cellulose acetate
fiber. For example, it is known in the art to use a
filter obtained by shaping a nonwoven fabric and a
filter (paper filter) obtained by shaping a paper
(having undergone creping treatment) which are free of
hardness increasing agents (agents leading to an
increase of filter hardness), for example, a hardener
inclusive of a plasticizer, such as triacetin, and
binders added to bind the filter material together (for
example, polyvinyl alcohol, polyvinyl acetate,
polyethylene glycol, dimethyl phthalate, diethyl
phthalate and the like). These filter materials can
also be used in the present invention.
It has been difficult for the filter material free
of any hardness increasing agent to achieve the filter
hardness equivalent to that of the cellulose acetate
filter having triacetin mixed therein. However, the
filter hardness equivalent to or higher than that of
the cellulose acetate filter having triacetin mixed
therein can be achieved by the employment of the
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high-rigidity and high-permeability paper according to
the present invention.
The filter including the filter material free of
any hardness increasing agent exerts an additional
advantage when it is used in a filter-tipped cigarette
having any of flavors (for example, menthol, limonene,
peppermint oil or spearmint oil; an ester such as ethyl
acetate, ethyl butyrate or ethyl benzoate; an alcohol
such as linalool, nerol or geraniol; a phenol such as
anethole; an aldehydes such as cinnamaldehyde or
vanillin; a lactone and a pyrazine), together with
triacetin, sorbed in the cellulose acetate fiber.
For example, in the current menthol cigarette,
menthol is mixed in cut tobacco, and a cellulose
acetate filter containing triacetin is fitted thereto.
However, in the current cellulose acetate filter, the
menthol contained in the cigarette together with
triacetin is sorbed in the cellulose acetate fiber with
time. The menthol sorbed in the cellulose acetate
fiber does not migrate into the mainstream smoke during
smoking. Accordingly, it is known that even when
menthol is present in the cigarette, the menthol
delivery into the mainstream smoke is decreased with
time in accordance with the sorption of menthol in the
filter. In contrast, in the filter material, such as a
paper filter, free of any plasticizer, hardener or
binder, the sorption of menthol in the filter with time
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does not occur as different from the cellulose acetate
filter containing a plasticizer, and menthol remains in
the cut tobacco. Therefore, even when the amount of
menthol in the cigarette is the same, the amount of
menthol delivered from the cut tobacco during smoking
is greater to thereby ensure a menthol delivery higher
than in the use of the cellulose acetate filter
containing triacetin. In addition, as the sorption of
menthol in the filter is avoided, the menthol delivery
into the mainstream smoke during smoking is stable with
time. Similar effects can be exerted when a flavor,
such as menthol, is added to the filter per se, or when
it is added to an aluminum-laminated paper within a
cigarette package. Moreover, these effects can be
exerted when even in the use of a cellulose acetate
fiber, the addition amount of triacetin causing the
sorption is decreased, or when a substance less likely
to invite the sorption than triacetin (for example,
polyvinyl alcohol, polyvinyl acetate, polyethylene
glycol, an epoxy resin or the like) is used as the
hardness increasing agent.
Needless to state, in the multisegment filter, a
filter plug formed of a filter material not containing
any hardness increasing agent can be combined with a
filter plug formed of a cellulose acetate fiber.
Further, the filter of the present invention can
include a filter plug having activated charcoal
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particles (charcoal) added thereto. In the single-
segment filter, activated charcoal particles can be
mixed in a single filter plug. In the multisegment
filter, generally, activated charcoal particles are
added to a filter plug upstream of the most downstream
filter plug.
Still further, the filter of the present invention
can have the structure of a recessed filter as
described in the pamphlet of International Publication
WO 00/00047 and Jpn. PCT National Publication No. 2004-
516814. Illustratively, in that case, when use is
formed of a single-segment filter, the cylindrical body
of the single filter plug is extended out of the
downstream end face of the filter material so as to
provide a recess portion. When use is formed of a
multisegment filter, the shaping paper is extended out
of the downstream end face of the most downstream
filter plug so as to provide a recess portion.
The present invention will be described below with
reference to the drawings. Like elements are
identified by like reference numerals through all the
drawings.
FIG. 1 is a partially developed schematic
perspective view of a filter-tipped cigarette 100
provided with a single-segment filter.
The filter-tipped cigarette 100 includes a
cigarette main body 110 and a filter plug 120 provided
CA 02708837 2010-06-10
at one end of the cigarette main body 110. The
cigarette main body 110 is identical to conventional
cigarettes and includes a tobacco rod and a cigarette
paper with which the circumference of the tobacco rod
5 is wrapped, both not shown. The tobacco rod is formed
of a tobacco filler, such as cut tobacco. The filter
plug 120 includes a cylindrical body 122 of filter plug
wrapper which is cylindrically shaped 121 and a filter
material 123 disposed in the cylindrical body 122. The
10 cigarette main body 110 and the filter plug 120 are
joined to each other by means of a tipping paper 130 so
that the end faces thereof unite with each other in the
same fashion as in conventional filter-tipped
cigarettes. The tipping paper 130 can be provided with
15 ventilation holes 131.
In the filter-tipped cigarette shown in FIG. 1,
the high-rigidity and high-permeability paper according
to the present invention is used as the filter plug
wrapper 121.
FIG. 2 is a partially developed schematic
perspective view of a filter-tipped cigarette 200
provided with a two-segment filter as an example of the
multisegment filter.
In the filter-tipped cigarette 200, a two-segment
filter 210 is fitted to one end of a cigarette main
body 110. The two-segment filter 210 includes two
filter plugs 220 and 230. The upstream filter plug 220
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includes a cylindrical body 222 of filter plug wrapper
which is cylindrically shaped 221 and a filter material
223 disposed in the cylindrical body 222. Likewise,
the downstream filter plug 230 includes a cylindrical
body 232 of filter plug wrapper which is cylindrically
shaped 231 and a filter material 233 disposed in the
cylindrical body 232. The two filter plugs 220 and 230
are joined to each other by means of a shaping paper
240 so that the end faces thereof unite with each
other. The cigarette main body 110 and the two-segment
filter 210 are joined to each other by means of a
tipping paper 130 so that the end faces thereof unite
with each other in the same fashion as in conventional
filter-tipped cigarettes.
In the filter-tipped cigarette shown in FIG. 2,
either or both of the filter plug wrappers 221 and 231
can be formed of the high-rigidity and high-
permeability paper according to the present invention.
As most smokers generally put the downstream
filter plug 230 in the mouth, the filter hardness is
often felt by the lips. Therefore, when the filter
plug wrapper 231 of the downstream filter plug 230 is
formed of the high-rigidity and high-permeability paper
according to the present invention, even if the filter
plug wrappers of other filter plugs are not formed of
the high-rigidity and high-permeability paper, the
smokers can feel the retention or increase of the
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filter hardness. Further, the smokers hold the
cigarette with their fingers during smoking, so that
the filter hardness may be felt by the fingers. In
that case, it is desirable to use the high-rigidity and
high-permeability paper according to the present
invention in the filter plug wrapper 221 of the
upstream filter plug 220 near the cut tobacco.
Needless to state, when the high-rigidity and high-
permeability paper according to the present invention
is used in both the filter plug wrappers 221 and 231,
the filter hardness can be simultaneously felt by the
lips and fingers. Moreover, when it is intended to
retain or increase the hardness of the whole of the
filter with respect to the cigarette provided with the
multisegment filter, the intention can be achieved by
using the high-rigidity and high-permeability paper
according to the present invention in the filter
shaping paper 240 of the multisegment filter. In that
case, both the filter plug wrappers 221 and 231 may be
formed of any of conventional filter plug wrappers
(rigidity (stiffness): 10 to 15, air permeability: 70
to 30,000 CORESTA units, thickness: 30 to 80 pm, and
basis weight: 15 to 27 g/m2). When it is intended to
further increase the filter hardness, the intention can
be achieved by not only using the high-rigidity and
high-permeability paper in the filter plug wrapper 221
and/or 231 but also using the high-rigidity and
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high-permeability paper according to the present
invention in the shaping paper 240 as well, namely,
implementing the double application of the high-
rigidity and high-permeability paper.
FIG. 3 is a partially developed schematic
perspective view of a filter-tipped cigarette 300
provided with a recessed single-segment filter.
The cigarette 300 provided with a recessed filter
includes a cigarette main body 110 and a filter plug
320 provided at one end of the cigarette main body 110.
The filter plug 320 includes a cylindrical body 322 of
filter plug wrapper which is cylindrically shaped 321
and a filter material 323 disposed in the cylindrical
body 322. The cylindrical body 122 is extended out of
the downstream end face of the filter material 323 so
as to provide a recess portion 324. The cigarette main
body 110 and the filter plug 320 are joined to each
other by means of a tipping paper 130 so that the end
faces thereof unite with each other in the same fashion
as in conventional filter-tipped cigarettes. The
tipping paper 130 can be provided with ventilation
holes 131.
In the filter-tipped cigarette shown in FIG. 3,
the high-rigidity and high-permeability paper according
to the present invention is used as the filter plug
wrapper 321.
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EXAMPLE
The present invention will be described below with
reference to the following Examples.
Example 1
Filter plugs were produced in accordance with the
routine procedure using the papers indicated in Table 1
above as filter plug wrappers. The employed filter
material consisted of a conventional cellulose acetate
fiber tow having triacetin added thereto in an amount
corresponding to 6% by weight based on the weight of
the cellulose acetate fiber tow. Each of the filter
plugs had a circumference of 24.5 mm and a length of
25 mm. Each of the filter plug wrappers covered the
circumference of the filter material in just
proportion. The hardness of each of the obtained
filters was measured.
In nature, the hardness of each of the filters
should be measured in the condition of the filter
fitted to the cigarette. However, due to problems
relating to measuring instruments, it is difficult to
measure the hardness of each of the filters in the
condition of the filter fitted to the cigarette.
Therefore, the hardness of each of the filters was
measured in the form of a filter plug before being
fitted to the cigarette (hereinafter, the filter
hardness was measured by the same measuring method).
The filter hardness was measured using NFQA
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(filter quality measuring instrument) manufactured by
JT TOSHI. The results are shown in FIG. 4. The filter
hardness was calculated from a strain occurring on the
filter upon the application of a given load.
5 Accordingly, the less the strain, the greater the
filter hardness is. Thus, in FIG. 4, the less the
value of filter hardness, the harder the filter is.
It is apparent from FIG. 4 that the filter
hardness of each of the filter plugs provided with the
10 high-rigidity and high-permeability papers Si to S4
according to the present invention is increased over
that of the filter plug provided with the now usually
employed filter plug wrapper P. All the filter plugs
provided with the high-rigidity and high-permeability
15 papers Sl to S4 according to the present invention
exhibited an air permeability of 1000 CORESTA units or
higher. Further, the high-rigidity paper S4 exhibiting
an air permeability equivalent to that of the now
usually employed filter plug wrapper P could be
20 available.
Therefore, using the high-rigidity and high-
permeability paper according to the present invention
makes it feasible to not only achieve the retention or
increase of the filter hardness but also avoid the
problems of the prior art of making ventilation holes,
namely, an increase of cigarette manufacturing cost, a
low versatility to a variety of cigarette products
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including a low-tar cigarette or the like and a poor
stability of product quality.
Example 2
Filter plugs with the same size as in Example 1
were produced using the conventional filter plug
wrapper P and high-rigidity and high-permeability paper
S4 indicated in Table 1. The filter material was the
same conventional cellulose acetate fiber tow as in
Example 1, but the amount of triacetin added to the tow
was changed (amounts equivalent to 0 to 12% by weight
based on the weight of cellulose acetate fiber). The
hardness of each of the obtained filter plugs was
measured in the same manner as in Example 1. The
results are shown in FIG. 5. In FIG. 5, the line a
indicates the results of the use of the filter plug
wrapper P, and the line b indicates the results of the
use of the high-rigidity and high-permeability paper
S4.
It is apparent from FIG. 5 that when the high-
rigidity and high-permeability paper S4 is used,
regardless of the amount of triacetin added, the filter
hardness is increased over that of the filter plug
using the conventional filter plug wrapper P.
As aforementioned, in the current cigarettes,
triacetin is added to the filter in an amount of 5 to
10% by weight based on the weight of the filter
material. However, it is seen that when the
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high-rigidity and high-permeability paper S4 is used,
the filter hardness can be increased without the need
to increase the amount of triacetin.
In the instances where the amount of triacetin is
less, it is found that the filter hardness exhibited
when the conventional filter plug wrapper P is used and
the amount of triacetin is about 6% by weight can be
achieved by the use of triacetin in an amount of about
3% by weight when the high-rigidity and high-
permeability paper S4 is used. Therefore, even when
the amount of triacetin is less, the hardness
equivalent to that of the current filter can be
achieved by the use of the high-rigidity and high-
permeability paper S4.
Example 3
So-called paper filter plugs were produced using
the papers indicated in Table 1. The filter material
used was a creped pulp paper. The configuration of
each of the obtained filter plugs was the same as in
Example 1. All the filter plugs exhibited an air-flow
resistance of 350 mmH2O/120mm. The hardness of each of
the obtained filter plugs was measured in the same
manner as in Example 1. The results are shown in
FIG. 6.
It is apparent from FIG. 6 that the paper filter
plugs wrapped with the high-rigidity and high-
permeability papers according to the present invention
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exhibit the same satisfactorily increased hardness
values as those of the cellulose acetate filter plugs
of Example 1 wrapped with the high-rigidity and high-
permeability papers according to the present invention.
Further, an increase of filter hardness up to the level
equivalent to the filter hardness exhibited by the
cellulose acetate filter having triacetin added in an
amount of 6% by weight can be achieved by the
application of the present invention.
Example 4
Filter-tipped cigarettes were produced by fitting
each of the cellulose acetate filter plug produced
using the conventional filter plug wrapper P in Example
1 and the paper filter plug produced using the high-
rigidity and high-permeability paper S4 in Example 3 to
a cigarette main body by means of a tipping paper.
Menthol was added in an amount of 3.0 mg per cigarette
to the cut tobacco of the cigarette main body. The
obtained filter-tipped cigarettes were stored in an
atmosphere conditioned at 22 C and a relative humidity
of 60% from immediately after the completion of the
production up to 12 weeks. The existence ratio of
menthol in the cut tobacco and filter material during
the storage period was measured by the method to be
described below. The results are shown in FIG. 7 and
FIG. 8. FIG. 7 shows the results with respect to the
cellulose acetate filter plug. FIG. 8 shows the
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results with respect to the paper filter plug. In
FIG. 7 and FIG. 8, each of the shaded portions
indicates the ratio of menthol in the filter material,
and each of the blank portions indicates the ratio of
menthol in the cut tobacco.
With respect to both the filter-tipped cigarettes
during the above storage period, the menthol delivery
into mainstream smoke (menthol/tar ratio (M/T ratio))
was measured by the method to be described below. The
results are shown in FIG. 9. In FIG. 9, the line a
indicates the results with respect to the cigarette
with paper filter, and the line b indicates the results
with respect to the cigarette with cellulose acetate
filter.
<Method of measuring the amount of menthol in cut
tobacco and filter material>
Each of the cigarettes was divided into a cut
tobacco portion (including the cigarette paper) and a
filter portion.
Thereafter, the cut tobacco portion was put in
methanol, shaken at room temperature for 40 minutes and
allowed to stand still for 24 hours. The mixture was
shaken once more for 40 minutes, and the supernatant
was separated as a menthol extract.
On the other hand, the filter portion was put in
methanol, shaken at room temperature for 40 minutes and
allowed to stand still for 24 hours. The supernatant
CA 02708837 2010-06-10
was separated as a menthol extract.
The thus obtained menthol extracts were analyzed
by a gas chromatograph equipped with a hydrogen flame
ionization detector (FID) as a detector. The quantity
5 of menthol was determined by an internal standard
method. As the internal standard, 1,3-butanediol was
used.
<Method of measuring menthol/tar ratio>
The tar contained in tobacco mainstream smoke was
10 measured in accordance with ISO 3308 and 4387.
With respect to the menthol contained in tobacco
mainstream smoke, in accordance with ISO 4387, the
mainstream smoke was trapped in a Cambridge filter, and
the Cambridge filter was put in methanol and shaken at
15 room temperature for 40 minutes. The supernatant was
separated as a menthol extract. The thus obtained
menthol extract was analyzed by a gas chromatograph
equipped with FID as a detector. The quantity of
menthol was determined by an internal standard method.
20 As the internal standard, 1,3-butanediol was used.
The menthol/tar ratio (M/T ratio) was calculated
from the values of the amounts of tar and menthol in
mainstream smoke determined by the above methods.
The obtained results attest to the migration of
25 menthol from the cut tobacco portion to the filter
portion when the cellulose acetate filter is used.
Consequently, it is apparent that the menthol delivery
CA 02708837 2010-06-10
26
is lowered with time. In contrast, when the paper
filter is used, menthol does not migrate into the
filter and remains in the cut tobacco. As a result, as
compared with the use of the cellulose acetate filter,
not only is the menthol delivery stabilized with time
but also a high menthol delivery can be achieved.
As apparent from the above, the application of the
present invention makes it feasible to achieve a
menthol cigarette that while retaining its filter
hardness, exhibits a high M/T ratio, namely, a high
menthol delivery even when a paper containing no
hardness increasing agent is used as the filter
material.
