Note: Descriptions are shown in the official language in which they were submitted.
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CIGARETTE WITH EMBOSSED WRAPPER PAPER
Technical Field
The present invention relates to a cigarette,
and more specifically to a cigarette whose tobacco
mainstream smoke is reduced in carbon monoxide amount.
Background Art
Nowadays, various requirements are posed on
cigarettes. One of such requirements is to reduce
the amount of carbon monoxide in the mainstream smoke.
Jpn. Pat. Appln. KOKAI Publication No. 10-99067
(Japanese Patent No. 3206885), which was filed by the
applicant of the present invention, discloses that when
cut tobacco is wrapped with an embossed cigarette paper
sheet, not only the falling off of cut tobacco from the
tip end of the cigarette can be prevented, but also the
mass ratio of carbon monoxide to tar (CO/T ratio) in
the mainstream smoke can be reduced.
An object of the present invention is to provide
a cigarette which can further reduce the amount of
carbon monoxide in the tobacco mainstream smoke,
thereby achieving a further low CO/T ratio.
Disclosure of Invention
In an attempt to achieve the above-described
object, the inventors of the present invention have
conducted studies in detail on embossing made on
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cigarette paper sheet. As a result, they have found that the above-described
object can be achieved by embossing cigarette paper so as to have a certain
depth or more and by setting a cut width of cutting tobacco used at a certain
width or more. The present invention is based on this finding.
Thus, according to the present invention, there is provided a cigarette
comprising a tobacco portion having cut tobacco wrapped with a cigarette paper
sheet into a rod shape, the cut tobacco having a cut width of 1.2 mm or more.
Projections having a height which corresponds to 1/3 or more of the thickness
of
the cigarette paper sheet are formed from the inner surface of the sheet in
array
extending partially or entirely on the surface of the cigarette paper sheet,
the
sheet being arranged with the projections directed towards the cut tobacco
side.
These projections advantageously have a truncated conical shape. The
projections having said height and the cut width of the cut tobacco
synergistically reduce an amount of CO generated from the cigarette.
In the present invention, it is preferable that the cut tobacco has a cut
width of 2.0 mm or more.
In the present invention, the cigarette paper usually has a thickness of 10
to 50 pm.
Brief Description of Drawings
FIG. 1 is a sectional view schematically showing a cigarette according to
an embodiment of the present invention;
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FIG. 2A is a plan view showing an example of
a embossed cigarette paper sheet used in the present
invention; and
FIG. 2B is a sectional view taken along the line
IIB-IIB of the cigarette paper sheet shown in FIG. 2A.
Best Mode for Carrying Out the Invention
The present invention will now be described in
more detail.
The cigarette of the present invention includes
a tobacco portion having cut tobacco wrapped with a
cigarette paper sheet into a rod shape. In the present
invention, the cut tobacco has a predetermined width,
whereas the cigarette paper sheet has projections
formed in array from its inner surface side to have
a predetermined height. The cigarette paper sheet is
disposed such that the projections are directed towards
the cut tobacco side.
FIG. 1 is an enlarged sectional view schematically
showing a portion of a cigarette according to
an embodiment of the present invention. As shown in
FIG. 1, a cigarette 10 includes a cut tobacco rod 12
in which cut tobacco is filled into a columnar shape,
and the circumference of the rod is wrapped with a
cigarette paper sheet 13, thus constituting a tobacco
portion 11.
In the present invention, the cut tobacco pieces
constituting the cut tobacco rod 12 have a cut width of
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1.2 mm or more. When the cut width is less than
1.2 mm, the effect of reducing carbon monoxide in the
mainstream smoke cannot be sufficiently obtained even
if such cut tobacco-is combined with the cigarette
paper of the present invention, which will be later
described. It is more preferable that the width of the
cut tobacco pieces is 2.0 mm or more. In the present
invention, the width of the cut tobacco pieces is
usually up to 3.0 mm. It should be noted that the
cut tobacco having such a width can be obtained by
a conventionally known method (See, for example,
Jpn. Pat. Appln. KOKAI Publication No. 2000-224978).
The cigarette paper sheet 13 wrapping the cut
tobacco rod 12 has projections 13a formed in array in
its inner surface, the projection having a height
corresponding to 1/3 or more of the thickness of the
cigarette paper sheet 13. The projections 13a are
directed towards the cut tobacco rod 12 side. If the
height of the projections taken from the inner surface
of the cigarette paper sheet is less than 1/3 of the
thickness of the sheet, the effect of reducing carbon
monoxide in the mainstream smoke cannot be sufficiently
obtained even if such cigarette paper is combined with
the cut tobacco pieces having a width of 1.2 mm or
more. In the present invention the height of the
projections 13a is usually not more than 10 times
the thickness of the cigarette paper sheet.
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The projections 13a in the cigarette paper sheet 13 are
formed usually by an embossing process in which the
sheet is embossed with use of means such as a knurl
member. It is preferable that the embossing provides
5 a pattern of lattice of recesses (grooves).
The cigarette paper to be embossed by the present
invention is the one that is generally used for
cigarettes. Such cigarette paper can have a basis
weight of 15 to 60 g/m2, and it can contain a filler
such as calcium carbonate in an amount of 0 to 60% by
mass and a burn aid such as sodium citrate in an amount
of 0 to 10% by mass. The thickness of the cigarette
paper is usually 30 to 50 m. The cigarette paper can
have an air permeability of 0 to 100 CORESTA Unit
(C.U.) before embossing, while it can have an air
permeability of 0 to 200 C.U. after the embossing.
Needless to say, a cigarette according to the
present invention may have a filter, usually used for
ordinary cigarettes, attached to the proximal end of
the tobacco portion using tipping paper.
FIG. 2 is a plan view showing a part of an inner
surface of the embossed cigarette paper sheet 13, and
FIG. 2B is a cross sectional view taken along the line
IIB-IIB in FIG. 2A. Both FIGURES show enlarged views.
The emboss applied on the cigarette paper sheet 13
shown in FIG. 2 is a rectangular lattice (a square
lattice or rectangular lattice) pattern of grooves
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having substantially the same shape, and the pattern is
formed entirely on the paper sheet 13 except for the
lapping portions used for gluing.
In FIGS. 2A and 2B there are shown grooves 131-al
to 131-a4 having an inverted trapezoidal shape in
cross-section, which extend in parallel with each other
in right and left directions of the FIGURE (to be
referred to as "lateral" direction hereinafter, which
may correspond to the longitudinal axis direction of
the cigarette), and grooves 131-b1 to 131-b6 having
an inverted trapezoidal shape in cross-section, which
extend in parallel with each other in a direction
orthogonal to the above grooves (to be also referred
to as "orthogonal" direction hereinafter). Each of
the rectangular regions in plan defined by the grooves
131-al to 131-a4 and the grooves,131-b1 to 131-b6
constitutes, three-dimensionally, a projection 132
(which corresponds to a projection 13a in FIG. 1)
projecting in the form of tetragonal prismoid. The
top surface of the tetragonal prismoid has a flat
rectangular shape. The cigarette paper sheet 13 is
wrapped around the cut tobacco rod 12 shown in FIG. 1
such that the rectangular top surfaces of the prismoid
are abutted against the tobacco rod.
Next, preferable sizes of the embossing pattern
will now be described together with the thickness of
the cigarette paper sheet 13. The preferable sizes
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fall within the following ranges where, as shown in
FIGS. 2A and 2B. A and A' represent the length of the
substantially rectangular top surface of the projection
132 in the orthogonal direction and in the lateral
direction, respectively; B and B' represent the length
taken from the base of the projection 312 to the edge
of the rectangular top surface in the orthogonal
direction and in the lateral direction, respectively; C
and C' represent the width of the bottom portion of the
groove extending in the lateral direction and in the
orthogonal direction, respectively; D is defined as an
emboss pitch in the orthogonal direction (A + 2B + C);
D' is defined as an emboss pitch in the lateral
direction (A' + 2B' + C'); E represents the depth of
each groove (which is also the height of the projection
132 or the emboss depth ED); and F represents the
thickness of the cigarette paper sheet 13 (before being
embossed):
A and A': each 5 to 1000 m(preferably, each 5
to 400 m)
B and B' : each 10 to 500 m(preferably, each 10
to 200 g m)
C and C': each 0 to 400 u m(preferably, each 200
to 300 m)
E: 10 to 300 Fcm (preferably, each 40 to 150 um)
F: 10 to 50 gm (preferably, each 25 to 40 m) .
It should be noted that the emboss depth can be
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measured using a probe type three-dimensional surface
roughness measurement instrument (for example, SE-3AK
of Kosaka Laboratory Ltd.).
Each embossed dot shown in FIG. 2 has a shape of
tetragonal prismoid; however, the present invention is
not limited thereto. For example, emboss dots having
conical shapes (including pyramids and circular cones)
and truncated conical shapes other than a tetragonal
prismoid (for examples, a prismoid other than a
tetragonal prismoid, such as a trigonal or pentagonal
prismoid, and a circular truncated cone) can be used.
Of these, emboss dots having a shape of a truncated
cone (prismoid and circular truncated cone) are
preferable, and emboss dots having a tetragonal
prismoidal shape is particularly preferable.
The cigarette of the present invention employs cut
tobacco having the predetermined width and, at the same
time, a cigarette paper sheet that has been specifi-
cally embossed. Thus, the amount of carbon monoxide in
the mainstream smoke is synergistically reduced, and
accordingly, the CO/T ratio is synergistically reduced.
The present invention will now be descried in
detail by way of Examples; however, the present
invention should not be limited thereto.
Examples
Cigarettes having a structure similar to that of
an ordinary filter-tipped cigarette (diameter: 8 mm,
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length of tobacco rod: 59 mm, length of filter: 25 mm)
were prepared using the cut tobacco and cigarette paper
sheets that had the specifications described below.
Tipping paper was attached to the proximal end portion
of each of the cigarettes prepared, and thus cigarette
samples listed in TABLE 1 below were prepared. Five
cigarette samples were prepared for each cigarette
specification.
<Cut tobacco>
Tar value: 5 mg per cigarette
Width of cut piece: 0.8 mm or 2 mm
<Cigarette paper A (not embossed)>
Basis weight: 22 g/m2
Filler: calcium carbonate
Amount of filler used: 28% by mass
Burn aid: sodium citrate
Amount of burn aid added: 1% by mass
Thickness: 32 m
Air permeability: 24 C.U.
<Cigarette paper B (embossed)>
Basis weight: 22 g/m2
Filler: calcium carbonate
Amount of filler used: 28% by mass
Burn aid: sodium citrate
Amount of burn aid added: 1% by mass
Thickness: 32 m
Emboss pitch: 0.64 mm
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Emboss depth: 85 jim
Emboss shape: tetragonal prismoid
Emboss dot width (corresponding to A + 2B in
FIG. 2): 0.4 mm
5 Air permeability: 80 C.U.
Wrapping state: wrapping with the projections on
cut tobacco side
Each of the cigarette samples was placed
*
vertically on a smoking device (RGC system R26 of
10 Borgwaldt Co.) and ignited at its distal end. Each
sample was statically burned until its char line
reaches a point 5 mm away from the distal end of the
tipping paper and at that point each sample was puffed
one time (puffing time: 2 seconds; puffed volume
35 mL), in order to eliminate the effects of dilution
and diffusion from the cigarette paper sheet. The
mainstream smoke was collected in a gas bag (Tedler bag
of Supelco Co.). The collected mainstream smoke was
subjected to a gas chromatography (Micro GC M200H*of
Agilient Co.) to measure the amount of carbon monoxide
(CO). The results are shown also in TABLE 1 below.
* trademarks
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TABLE 1: CO amount in the mainstream smoke of
each ci arette sam le
Width CO amount
CO amount
Cigarette of cut reduction
paper tobacco (average) rate Remarks
pieces (mg/puff) (average)
Cigarette
0.8 mm 2.010 Reference Control
paper A
Cigarette 2 mm 1.735 14% Comparative
paper A Example
Cigarette Comparative
0.8 mm 1.700 15%
paper B Example
Cigarette
2 mm 1.182 41% Invention
paper B
As can be seen from FIG. 1, even merely when the
width of the cut tobacco pieces employed was set to
1.2 mm or more, or merely when the cigarette paper
sheet was subjected to the embossing process, the
amount of CO generated was reduced by about 15%.
However, when these conditions are combined together,
the amount of CO could be cut down even by 41%. From
these results, it is clear that when the cut tobacco
having the predetermined cut width and the cigarette
paper sheet that has been subjected to the specified
embossing, which are defined by the present invention,
are used in combination, the above-described
synergistic effect can be achieved.
As described above, according to the present
invention, there is provided a cigarette that produces
a further less amount of carbon monoxide in its tobacco
mainstream smoke.
