Technical Field
[0001] The present invention relates to a low flame-spreading cigarette that is unlikely
to cause flame spread from the kindling to the surroundings so as not to allow the
ignited cigarette to cause fire by, for example, the carelessness of the smoker.
Background Art
[0002] Cigarettes have been proposed, including, for example, a cigarette having a cellulose
paper band, which is 2 to 20 mm wide, formed on the cigarette paper to impart self-extinguishing
property(see Japanese Patent Disclosure (Kokai) No. 63-85200), and a cigarette in
which a band coated with a flame retardant substance is formed on the cigarette paper
(see Japanese Patent Disclosure (Kokai) No. 7-300795), in order to prevent the spread
of flame from the kindling to, for example, the floor, where the cigarette is dropped
onto, for example, the floor by the carelessness of the smoker. Further, a cigarette
paper having a nonflammable substance pasted thereto is also known. These technologies
are based on the idea that a region having high flammability and another region having
low flammability are formed in the cigarette paper such that ordinary smoking can
be performed in the region having high flammability and that the cigarette is extinguished
in the region having low flammability.
[0003] It is also known well in the art that, if the burn rate of the cigarette is lowered
in an attempt to decrease the amount of the sidestream smoke per hour, it is possible
to provide a cigarette that can be self-extinguished. As such a cigarette, a cigarette
has been proposed, in which shredded tobacco are wrapped with a cigarette paper having
a small amount of loading material used an inner paper and with an ordinary cigarette
paper used as an outer paper (see Japanese Patent No. 2,572,488). Also, as a cigarette
with a low sidestream smoke, a cigarette has been proposed, in which a smoking material
rod having a loading density of 100 to 260 mg/cm
3 is wrapped by a wrapping paper having an air permeability not higher than 7 CORESTA
units (see Japanese Patent No. 3,001,582). Further, a cigarette has been proposed,
in which the burn rate is lowered by using a wrapping paper having a low air permeability
(7 CORESTA units), having a small amount of loading material, and having a small basis
weight (see International Publication WO 01/48316).
[0004] However, in the case of using a cigarette paper including a nonflammable region,
the tobacco burn is made nonuniform because the cigarette paper includes a flame retardant
region and a flammable region. Also, the smoking taste is made nonuniform. Also, in
the method of lowering flame spread by lowering the burn rate, the flame spread is
lowered by lowering the air permeability of the cigarette paper for this purpose.
As a result, the ventilation effect produced by the cigarette paper is lowered so
as to increase the amount of the carbon monoxide (CO) contained in the mainstream
smoke, increasing the carbon monoxide/tar ratio (C/T ratio). Further, if the air permeability
of the cigarette paper is lowered, the taste of the tobacco is changed so as to give
rise to the problem that an ordinary smoker is caused to feel an incompatibility.
[0005] On the other hand, it is known that a cigarette using a cigarette paper having a
low mixing ratio of loading material is lowered in the burn rate. However, it is experimentally
known that the cigarette goes out during static burn, and thus the amount of loading
material cannot be decreased excessively.
[0006] Therefore, an object of the present invention is to provide a cigarette, which is
substantially equal to an ordinary cigarette in smoking behavior and in the burn rate,
and which permits improving the C/T ratio in the mainstream smoke and exhibits low
flame spread.
Disclosure of Invention
[0007] As a result of research conducted in an effort to develop a low flame-spreading cigarette,
the present inventors have found that a cigarette achieving the above object can be
obtained merely by setting the inherent air permeability of the cigarette paper wrapping
the tobacco filler material rod and the amount of the loading material mixed in the
cigarette paper at prescribed values. The amount of loading material can be decreased
as much as possible within the range of maintaining the static burn by setting the
inherent air permeability of the cigarette paper to fall within a prescribed range.
The present invention is based on these findings.
[0008] According to the present invention, there is provided a cigarette comprising a tobacco
filler material rod and a cigarette paper containing pulp and a loading material,
wherein the cigarette paper has an inherent air permeability of more than 20 CORESTA
units but 80 CORESTA units or less and contains the loading material in an amount
of 1.0 to 5.0 g/m
2.
[0009] The cigarette of the present invention maintains static burn, and can exhibit a low
flame spread property such that, when left to stand on a substrate after static burn
over a prescribed distance, a median value of a moving distance of a char line of
the cigarette paper in an axial direction of the cigarette until the burn of the cigarette
is stopped is not larger than 8 mm.
[0010] According to a preferred aspect of the present invention, there is provided a cigarette
comprising a tobacco filler material rod and a cigarette paper wrapping the rod, wherein
the cigarette paper has an air permeability of more than 20 CORESTA units but 80 CORESTA
units or less, contains a loading material in an amount of 1.4 to 3.7 g/m
2 and also contains a burn adjusting agent in an amount of 0 to 0.6% by weight, and
the tobacco filler material is loaded at a loading density of 130 to 230 mg/cm
3.
Best Mode for Carrying Out the Invention
[0011] The present invention will be described in more detail below.
[0012] A cigarette according to the present invention comprises a tobacco filler material
rod and a cigarette paper wrapping the tobacco filler material rod. The cigarette
of the present invention has an outer appearance and shape similar to those of an
ordinary cigarette.
[0013] The tobacco filler material rod used in the cigarette of the present invention is
formed of, e.g., ordinary shredded tobacco. The shredded tobacco may contain expanded
tobacco and regenerated tobacco, and the central vein of tobacco leaf. It is preferable
that the loading density of the shredded tobacco is 130 to 260 mg/cm
3. If the loading density fails to fall within the range given above, it may sometime
become difficult to suppress sufficiently the flame spread even if the tobacco rod
is wrapped in the cigarette paper of the present invention. It is more preferable
that the loading density of the tobacco filler material is 130 to 230 mg/cm
3, further preferably 140 to 230 mg/cm
3. It suffices for the shredding width of the shredded tobacco to be equal to that
of ordinary shredded tobacco. However, in view of low flame spread, it is desirable
for the shredding width to be relatively large, i.e., 0.5 to 1.5 mm, more preferably
0.8 to 1.2 mm.
[0014] The cigarette paper used in the present invention is based on ordinary pulp such
as flax pulp used for forming ordinary cigarette paper and, thus, contains pulp. The
cigarette paper used in the present invention has an inherent air permeability (the
air permeability of the cigarette paper without any perforations made therein) of
more than 20 CORESTA units (C.U.) but 80 CORESTA units or less. If the inherent air
permeability of the cigarette paper sheet is not higher than 20 CORESTA units, the
C/T ratio is increased in the cigarette mainstream smoke that is generated during
the smoking stage. On the other hand, if the inherent air permeability of the cigarette
paper exceeds 80 CORESTA units, the nonuniformity of the air permeability is increased.
The inherent air permeability of the cigarette paper is desirably more than 20 CORESTA
units but 60 CORESTA units or less, and is more desirably 25 to 55 CORESTA units.
Incidentally, the cigarette paper may be perforated mechanically or electrically by
the ordinary method. The air permeability of the wrapping paper having such holes
is not particularly limited.
[0015] The cigarette paper of the present invention contains loading materials. The loading
materials that are generally used can be used, including a carbonate salt such as
calcium carbonate or potassium carbonate and a hydroxide such as calcium hydroxide
or magnesium hydroxide. The loading material is contained in the cigarette paper in
an amount of 1.0 to 5.0 g/m
2. If the amount of the loading material is smaller than 1.0 g/m
2, the cigarette goes out during static burn. Also, if the loading material is contained
in an amount exceeding 5.0 g/m
2, low flame spread cannot be achieved. It is desirable for the amount of the loading
material to be 1.4 to 3.7 g/m
2, more desirably, 1.6 to 3.3 g/m
2. Also, the amount of loading material in the cigarette paper is preferably 6 to 25%
by weight, more preferably 7 to 21% by weight, and furthermore preferably 8 to 17%
by weight.
[0016] The basis weight of the cigarette paper is preferably 17 to 28 g/m
2. If the basis weight is smaller than 17 g/m
2, it tends to be difficult to stably manufacture the cigarette paper sheet. Also,
if the basis weight exceeds 28 g/m
2, flame spread tends to be promoted. The basis weight of the cigarette paper is more
preferably 18 to 25 g/m
2, furthermore preferably 18 to 22 g/m
2.
[0017] It is possible to add a burn adjusting agent such as citric acid or its salt (such
as sodium salt or potassium salt) to the cigarette paper. The content of the burn
adjusting agent is preferably 0 to 1.0% by weight. If the amount of burn adjusting
agent exceeds 1.0% by weight, the C/T ratio tends to become high. The amount of burn
adjusting agent is more preferably 0 to 0.6% by weight, furthermore preferably 0.1
to 0.6% by weight.
[0018] Incidentally, the cigarette paper of the present invention, by having a tensile strength
of 10 to 20 N/15 mm or more, can make cigarettes, without difficulty, even if applied
to a high-speed cigarette making machine that permits manufacturing cigarettes at
a rate of 8,000 to 12,000 cigarettes/min. The tensile strength of the cigarette paper
can be controlled by controlling the beating degree of the pulp or by controlling
the amount of pulp used for manufacturing the cigarette paper sheet. The tensile strength
of the cigarette paper increases with increase in the amount of pulp per unit area
of the cigarette paper or in the beating degree of the pulp.
[0019] According to the present invention, a cigarette low in flame spread, and generating
mainstream smoke having a small C/T ratio is obtained in spite of the relatively high
inherent air permeability of the cigarette paper by setting the inherent air permeability
of the cigarette paper and the amount of the loading material contained in the cigarette
paper to fall within the ranges given above. Also, the cigarette of the present invention
permits exhibiting a burn rate substantially equal to that of an ordinary cigarette.
The low flame-spreading property of the cigarette of the present invention may be
such that, when left to stand on a substrate (10 superposed filter paper sheets) after
static burn over a prescribed distance, a median value of a moving distance of a char
line of the cigarette paper in an axial direction of the cigarette until the burn
of the cigarette is stopped is not larger than 8 mm, preferably 4 mm or lees (measured
according to ASTM E 2187-02b method). In a plurality of cigarettes of the present
invention, the most frequently obtained value of the moving distance of the char line
noted above may be 8 mm or less, preferably 4 mm or less.
[0020] The present invention will now be described with reference to Examples, but the present
invention is not limited thereto.
Examples and Comparative Examples
[0021] Shredded tobacco was wrapped in a flax pulp cigarette paper having the specification
shown in Table 1 such that the shredded tobacco had the loading density shown in Table
1 so as to fabricate 40 cigarettes for each case. Calcium carbonate was used as the
loading material, and sodium citrate was used as the burn adjusting agent. Flue-cured
shredded tobacco or blended shredded tobacco were used as the shredded tobacco. Table
1 also shows the inherent air permeability and the tensile strength of the cigarette
paper. Incidentally, the tensile strength shown in Table 1 was measured by using a
tensile strength tester STROGPAPHE-S manufactured by Toyo Seiki K.K. in accordance
with the method specified in Japanese Industrial Standards (JIS) P 8113-1998 (the
size of test piece: 15.0 mm X about 250 mm, the gripping distance: 180±2 mm, and the
pulling rate: 50 mm/min).
[0022] The static burn rates of the cigarettes thus fabricated were measured by the ordinary
method in respect of the fabricated cigarette. Also, the percent full length burn
on 10 superposed filter paper sheets was measured by the method specified in ASTM
E2187-02b. Further, measurement was made of the median value of the moving distance
of the char line of the cigarette paper in the axial direction of the cigarette after
the ignited cigarette was placed on the filer papers until the cigarette burning is
stopped (or went out). Table 2 shows the results.
[0024] As is apparent from the results given in Tables 2 and 3, the cigarette fabricated
by using the cigarette paper specified in the present invention and tobacco filler
materials exhibits excellent low flame spread and a small C/T ratio.
[0025] As described above, the present invention provides a cigarette, which permits a smoking
behavior similar to that of an ordinary cigarette, also permits a burn rate substantially
equal to that of an ordinary cigarette, further permits exhibiting a low flame spread,
and is small in C/T ratio in the generated mainstream smoke. Also, since a special
band and a special flame retardant substance are not used in the present invention,
the cigarette of the present invention continues to produce a prescribed taste under
ordinary smoking behavior.
1. A cigarette comprising a tobacco filler material rod and a cigarette paper wrapping
the rod, wherein the cigarette paper has an inherent air permeability of more than
20 CORESTA units but 80 CORESTA units or less and contains a loading material in an
amount of 1.0 to 5.0 g/m2.
2. The cigarette according to claim 1, wherein the cigarette paper has an inherent air
permeability of more than 20 CORESTA units but 60 CORESTA units or less.
3. The cigarette according to claim 1, wherein the cigarette paper has an inherent air
permeability of 25 to 55 CORESTA units.
4. The cigarette according to claim 1, wherein the cigarette paper contains the loading
material in an amount of 1.4 to 3.7 g/m2.
5. The cigarette according to claim 1, wherein the cigarette paper contains the loading
material in an amount of 1.6 to 3.3 g/m2.
6. The cigarette according to claim 1, wherein the cigarette paper contains the loading
material in an amount of 6 to 25% by weight.
7. The cigarette according to claim 1, wherein the cigarette paper contains the loading
material in an amount of 7 to 21% by weight.
8. The cigarette according to claim 1, wherein the cigarette paper contains the loading
material in an amount of 8 to 17% by weight.
9. The cigarette according to claim 1, wherein the cigarette paper has a basis weight
of 17 to 28 g/m2.
10. The cigarette according to claim 1, wherein the cigarette paper has a basis weight
of 18 to 25 g/m2.
11. The cigarette according to claim 1, wherein the cigarette paper has a basis weight
of 18 to 22 g/m2.
12. The cigarette according to claim 1, wherein the cigarette paper contains a burn adjusting
agent in an amount of 0.1 to 1.0% by weight.
13. The cigarette according to claim 1, wherein the cigarette paper contains a burn adjusting
agent in an amount of 0 to 0.6% by weight.
14. The cigarette according to claim 1, wherein the cigarette paper contains a burn adjusting
agent in an amount of 0.1 to 0.6% by weight.
15. The cigarette according to claim 1, wherein the tobacco filler material is loaded
at a loading density of 130 to 260 mg/cm3.
16. The cigarette according to claim 1, wherein the tobacco filler material is loaded
at a loading density of 140 to 230 mg/cm3.
17. The cigarette according to claim 1, wherein the tobacco filler material comprises
shredded tobacco.
18. The cigarette according to claim 17, wherein the shredded tobacco has a width of 0.5
to 1.5 mm.
19. The cigarette according to claim 1, wherein the loading material is selected from
the group consisting of calcium carbonate, potassium carbonate, calcium hydroxide
and magnesium hydroxide.
20. A cigarette comprising a tobacco filler material rod, and a cigarette paper wrapping
the rod, wherein the cigarette paper has an inherent air permeability of more than
20 CORESTA units but 80 CORESTA units or less, contains a loading material in an amount
of 1.4 to 3.7 g/m2 and also contains a burn adjusting agent in an amount of 0 to 0.6% by weight, and
the tobacco filler material is loaded at a loading density of 130 to 230 g/cm3.
21. The cigarette according to claim 20, wherein the cigarette paper has an inherent air
permeability of 25 to 55 CORESTA units, contains the loading material in an amount
of 1.6 to 3.3 g/m2 and also contains the burn adjusting agent in an amount of 0.1 to 0.6% by weight,
and the tobacco filler material is loaded at a loading density of 140 to 230 g/cm3.
22. The cigarette according to claim 1, which exhibits a low flame spread property such
that, when left to stand on a substrate after static burn over a prescribed distance,
a median value of a moving distance of a char line of the cigarette paper in an axial
direction of the cigarette until the burn of the cigarette is stopped is not larger
than 8 mm.
23. The cigarette according to claim 20, which exhibits a low flame spread property such
that, when left to stand on a substrate after static burn over a prescribed distance,
a median value of a moving distance of a char line of the cigarette paper in an axial
direction of the cigarette until the burn of the cigarette is stopped is not larger
than 8 mm.