Note: Descriptions are shown in the official language in which they were submitted.
CA 02645998 2009-02-23
1
D E S C R I P T I 0 N
LOW IGNITION PROPENSITY CIGARETTE PAPER
Technical Field
The present invention relates to a low ignition
propensity cigarette paper.
Background Art
A cigarette paper has been proposed which is
reduced in the air permeability of base cigarette paper
by applying a salt of alginic acid to at least a part
of the base cigarette paper such that a cigarette is
restrained from causing, for example, a floor to catch
fire from the burning butt when the cigarette falls on
the floor because of, for example, carelessness by the
smoker (see Jpn. Pat. Appln. KOKAI Publication No. 7-
300795).
Disclosure of Invention
In Jpn. Pat. Appln. KOKAI Publication No. 7-
300795, the air permeability of the cigarette paper
coated with a salt of alginic acid is measured.
However, the actual ignition propensities of the
cigarette paper are not measured.
The inventors of the present invention have made
studies as to the effect of sodium alginate out of
salts of alginic acid on the actual ignition
propensities of cigarette paper, and as a result, have
CA 02645998 2008-09-16
2
found that the coating required to exhibit the same
ignition propensities differs depending on the degree
of polymerization or viscosity of sodium alginate.
Specifically, it is an object of the present
invention to provide a cigarette paper exhibiting
significantly reduced ignition propensities with a
relatively small coating amount.
According to a first aspect of the present
invention, there is provided a low ignition propensity
cigarette paper comprising base cigarette paper having
a basis weight exceeding 22 g/m2, and a plurality of
burn limiting areas arranged apart from one another on
one surface of the base cigarette paper, wherein the
burn limiting areas are formed by applying sodium
alginate having a degree of polymerization of about 500
to about 900.
According to a second aspect of the present
invention, there is provided a low ignition propensity
cigarette paper comprising base cigarette paper having
a basis weight exceeding 22 g/m2, and a plurality of
burn limiting areas arranged apart from one another on
one surface of the base cigarette paper, wherein the
burn limiting areas are each formed by applying sodium
alginate whose 3% by weight aqueous solution exhibits a
viscosity of 19000 cP or more as measured at 25- C.
According to a third aspect of the present
invention, there is provided a low ignition propensity
CA 02645998 2008-09-16
3
cigarette paper comprising base cigarette paper
containing a filler in an amount of 2 g/m2 or more, and
having a basis weight exceeding 22 g/m2 and an inherent
air permeability of 30 to 60 CORESTA units, and a
plurality of burn limiting areas arranged apart from
one another on one surface of the base cigarette paper,
wherein the burn limiting areas are each formed by
applying sodium alginate in an amount less than 3 g/m2,
and the cigarette paper provides a cigarette exhibiting
a PFLB value of 0 to 10% when measured according to
ASTM E-2187-04.
Brief Description of Drawings
FIG. 1 is a partially broken schematic perspective
view illustrating an example of a cigarette wrapped
with a cigarette paper according to one embodiment of
the present invention.
Best Mode for Carrying Out the Invention
The present invention will be explained in more
detail.
A cigarette paper of the present invention is a
paper in which a plurality of burn limiting areas where
a burn limiting agent constituted of sodium alginate is
applied are provided apart from on another on a base
cigarette paper.
The base cigarette paper is ordinary cigarette
paper using, as the base, ordinary pulp such as flax
pulp. Such base cigarette paper may contain a
CA 02645998 2008-09-16
4
generally used filler, including a carbonate such as
calcium carbonate or potassium carbonate and a
hydroxide such as calcium hydroxide or magnesium
hydroxide in an amount of 2 g/m2 or more. The filler
may be contained in an amount of 2 to 8 g/m2 in the
base cigarette paper. The base cigarette paper usually
has a basis weight exceeding 22 g/m2. The basis weight
is usually 80 g/m2 or less and preferably more than
20 g/m2 but 28 g/m2 or less. The inherent air
permeability of the base cigarette paper is usually 30
to 60 CORESTA units.
The base cigarette paper may be added with a burn
adjusting agent such as citric acid or its salt (a
sodium salt, potassium salt). Generally, the burn
adjusting agent, if added, is used in an amount of 2%
by weight or less in the base paper.
A plurality of burn limiting areas, which are
respectively formed by application of a burn limiting
agent (sodium alginate), are arranged apart from one
another on one surface of the base cigarette paper.
When the cigarette paper wraps a tobacco rod, these
burn limiting areas may extend in the longitudinal
direction of the tobacco rod, so that they are arranged
in the form of plural stripes apart from one another in
the direction of the circumference of the tobacco rod.
Alternatively, these burning areas may extend in the
circumferential direction of the tobacco rod, so that
CA 02645998 2008-09-16
they are arranged in the form of plural circular bands
apart from one another in the longitudinal direction of
the tobacco rod.
In the present invention, sodium alginate is used
5 as the burn limiting agent. Alginic acid is polyuronic
acid consisting of two types of monomers, R-D-
mannuronic acid and a-L-guluronic acid. In an
embodiment of the invention, a sodium salt of alginic
acid having a degree of polymerization of 500 to 900 is
used. In another embodiment of the invention, sodium
alginate whose 3% by weight aqueous 3% solution
exhibits a viscosity of 19000 cP or more when measured
at 25 C is used. The degree of polymerization and
viscosity of alginic acid are correlated with each
other to some extent. When sodium alginate having such
a high degree of polymerization or viscosity is used,
the same level of reduced ignition propensities can be
attained even in a smaller coating amount than in the
case of using other sodium alginate. The above
viscosity is usually 40000 cP or less.
Generally, the total coating amount (dry basis) of
the sodium alginate burn limiting agent is less than
3g per m2 of the coating area. A coating amount of as
low as 0.2 to 2 g/m2 can achieve sufficiently reduced
ignition propensities. The cigarette paper according
to the invention can provide a cigarette (cigarette in
which a tobacco filler is wrapped by the cigarette
CA 02645998 2008-09-16
6
paper) exhibiting a percent full-length burn (PFLB) of
0 to 10% when measured according to ASTM E-2187-04.
A cigarette paper according to one embodiment of
the invention includes base cigarette paper containing
a filler in an amount of 2 g/m2 or more and having a
basis weight exceeding 22 g/m2 and an inherent air
permeability of 30 to 60 CORESTA units, and a plurality
of burn limiting areas arranged apart from one another
on one surface of the base cigarette paper. The burn
limiting area is formed by applying sodium alginate in
an amount less than 3 g/m2. A cigarette prepared by
winding the cigarette paper around wrapping a tobacco
filler rod with this cigarette paper exhibits a PFLB
value of 0 to 10% when measured according to ASTM E-
2187-04.
The low ignition propensity cigarette paper of the
invention is used to wrap a tobacco rod constituted of
a tobacco filler such as shredded tobacco, and usually,
the surface to which the burn limiting agent is applied
is brought into contact with the tobacco rod.
FIG. 1 illustrates a cigarette wrapped with a
cigarette paper to which the burn limiting agent is
applied in the form of a circular band.
Referring to FIG. 1, a cigarette 10 has a tobacco
rod 11 constituted of a tobacco filler 13 wrapped with
a base cigarette paper 12 in a columnar shape. The
tobacco rod 11 usually has a circumferential length of
CA 02645998 2008-09-16
7
17 mm to 26 mm and a length of 49 mm to 90 mm. An
ordinary filter 18 may be fitted to a proximal end
(i.e., the downstream end in the smoking direction) llb
of the tobacco rod 11 by using a tipping paper 17
according to an ordinary method.
A plurality of circular band areas 14 to which
burn limiting agents (sodium alginate) are applied are
formed on the base cigarette paper 12 and respectively
define burn limiting areas. These circular band burn
limiting areas 14 are formed apart from one another in
the longitudinal direction of the tobacco rod.
A usual burn area 15 to which no burn adjusting
agent is applied is defined between the adjacent band
burn limiting areas 14. Since this area 15 is
constituted of the part of the base cigarette paper 12,
it can be burned in the usual smoking condition like
the base cigarette paper 12 itself. Therefore, the
area 15 acts as the usual burn area. The base
cigarette paper 12 may be provided with, for example,
two or three circular band burn limiting areas 14.
Also, the circular band burn limiting area 14 may have
a width of 4 mm to 7 mm in the longitudinal direction
and its thickness may usually be 0.1 to 5 m. The
spacing between the adjacent burn limiting areas 14 is
preferably 18 mm to 25 mm.
In the cigarette illustrated in FIG. 1, no burn
limiting agent is applied to an area 16 at a distance d
CA 02645998 2008-09-16
8
from the distal end of the cigarette. The end part
where no burn limiting agent is applied constitutes a
usual burn area 16 and can correspond to the area
burned by one or two puffs of the usual cigarette. The
distance d may be designed to be 10 mm to 25 mm from
the distal end lla of the tobacco rod. It is not
particularly necessary to form the burn limiting area
14 on the inside surface of the cigarette paper
corresponding to the part of the cigarette paper 12
covered with the tipping paper 17.
Now, when the cigarette 10 is ignited at the
distal end lla of the cigarette rod 11 and smoked to
burn the cigarette, the cigarette can be burned like a
usual cigarette in the usual burn area 15 to be able to
enjoy a smoking taste. However, in the case of putting
the cigarette 10 in the burned state on inflammables
such as a carpet, tatami, wood products, fabrics and
clothes, the fire is extinguished by the heat
absorption of the burn limiting area 14 in a burning
direction and inflammables in combination with tobacco
shreds contained in the tobacco filler, which
suppresses the inflammables to catch fire.
The present invention will be explained by way of
Examples, which are, however, not intended to be
limiting of the invention.
Examples 1 to 6 and Comparative Examples 1 to 9.
First, the polymerization degree and viscosity of
CA 02645998 2008-09-16
9
sodium alginate used in the Examples and Comparative
Examples are shown in Table 1 below. All the sodium
alginates used are manufactured by KIMIKA (trademark)
Company and sodium alginates identified by ALG-l, ALG-
2, ALG-3, ALG-4 and ALG-5 are available under the
tradenames of ULV, IL-2, I-1, 1-5 and I-S,
respectively.
The viscosities shown in Table 1 are results when
200g of a 3% by weight aqueous sodium alginate solution
was placed in a 200 mL or 300 mL beaker, which was then
placed in a constant-temperature water bath, the
aqueous solution was kept at 25 0.5 C, the solution
was stirred slowly with a glass rod for about one
minute so as not to introduce air bubbles thereinto and
was then allowed to stand for 10 minutes, followed by
measuring the viscosity of the solution by a B-type
viscometer.
The 3% by weight aqueous sodium alginate solution
was applied to (printed on) base cigarette paper
(width: 27 mm, length: 1.500m) having a specification
as shown in Table 2 so as to have a fixed width of 7 mm
in the longitudinal direction in a stripe form at fixed
intervals of 20 mm by using a direct gravure system,
thereby forming a total of 56 burn limiting agent
coating areas. With regard to the obtained cigarette
paper, the total coating amount of sodium alginate was
measured using the following method. The results are
CA 02645998 2008-09-16
shown also in Table 2. As shown in Table 2, the
cigarette papers obtained in Examples 1 to 6 had the
coating amount of the burn limiting agent per m2 of the
area to which the burn limiting agent (sodium alginate)
5 was applied was 1.5 to 2g. When the coating amount of
the burn limiting agent is calculated based on unit
area of the cigarette paper, it is 0.39 to 0.52 g/m2
because the coating amount should be multiplied by
7/27.
10 The obtained cigarette paper was used to wrap a
tobacco rod made of American blend shreds (amount of
tar in the case of setting no filter: 19 to 20 mg) and
the obtained tobacco rod was cut such that the first
coating area was located with a band space of 5 mm from
the burning tip end of the cigarette. The length of
one cigarette was 59 mm and the cigarette had two burn
limiting agent coating areas.
The obtained cigarette was subjected to an
ignition propensity test according to ASTM E-2187-04 to
measure the PFLB value. The results are shown in Table
2.
<Measurement of the total coating amount of sodium
alginate>
The coating amount of sodium alginate was measured
in the following procedures according to "Quantitative
analysis method for sodium alginate in foods" described
in "Journal of Food Hygiene", vol. 5, pp. 297-302
CA 02645998 2008-09-16
11
(1988) without performing defatting, dilute sulfuric
acid treatment and deproteinization treatment.
The cigarette paper (length: 1.500m, width: 27 mm)
(about 1.0g) coated with the above burn limiting agent
was cut into 5 mm square, added with 40 mL of a 1% by
weight aqueous sodium bicarbonate solution, heated at
60 C in a hot bath for 5 minutes and then sufficiently
mixed and stirred, followed by centrifugation
(3500 rpm, 10 minutes; the same as follows) to obtain a
supernatant (extract). The extraction residue was
extracted again in the same manner as above to obtain a
supernatant (extract) and also, 20 mL of a 1% by weight
aqueous sodium bicarbonate solution was added to the
extraction residue, which was then sufficiently mixed
and stirred to obtain a supernatant (extract). The
obtained three extracts were combined and a 1% by
weight aqueous sodium bicarbonate solution was added to
the mixed extract to be 100 mL, which was used as a
test solution.
2 mL of a copper-hydrochloric acid solution (8.5M
hydrochloric acid containing 0.05% by weight of copper
sulfate) and 1 mL of a naphthoresorcinol solution (0.4%
by weight aqueous 1,3-dihydroxynaphthalene solution)
were added to each of 1 mL of a sodium alginate
standard solution (1% by weight aqueous sodium
bicarbonate solution containing sodium alginate at a
concentration of 0 to 0.2 mg/mL) and 1 mL of the above
CA 02645998 2008-09-16
12
test solution. Each solution was heated in a boiling
water bath for 65 minutes and then cooled in ice water.
4 mL of butyl acetate was added to the solution, which
was then shaken and centrifuged.
1 mL of the upper layer of the solution after the
centrifugation was collected, and diluted with the
addition of 3 mL of butyl acetate, and colorimetric
quantitative determination at 566 nm was conducted,
thereby calculating the total coating amount.
[Table 1]
Table 1:
Identification Polymerization
Viscosity
symbol of degree of alginic acid
(cP)
sodium alginate (Number of monomers)
ALG-1 30-180 900
ALG-2 250-400 4700
ALG-3 550-580 19800
ALG-4 650-670 30000
CA 02645998 2008-09-16
13
0
,~
000 o coo N LCD
. . O 0 O O O 0 0 0 0 0 0
a d' d' 000 N d, 't, LO
4-4 cq
t)p C)
4~
4) .
00 Lo LO I'll 00 cq LO Lo
C) co cV c'i -=1 ri r-i 14
an
U c~ co -t co 't co 't
cl cl c~ C cq ci N ci Lo Lo LO Lo LO LO Lo LO LO LO LO Lo LCD
Lj co co Co cc Co CCD CCD cc Coco CCD CC C
0)
0
CO co co CO m co co co co co co co co
o~~ ~ 3 0 0 0 0 0 0 0 0 0 0 0 0 0
c: cll LCD LCD LO LCD LO LCD LCD LCD LO 10 LCD LCD LCD
bi)
z Ln L6 LCD LCD LCD LCD LC LCD LCD LCD LCD 6 LIB
U LV GV G~7 G17 cV cV cq cal cV cam] cam] cal N
O
4-a ;m-4 cq
N N N N N N N N N N N N N
o N N N N N N N N N N N N N
W W W W W W W -- .ai --
ct cd t R m R
W U U U U 0 0 0 W W W W W W
N
f)
E-+
C)
r-I
CA 02645998 2008-09-16
14
When comparing Comparative Examples 2 and 3 with
Examples 1 and 2, it is seen that the amount of the
burn limiting agent (sodium alginate) required to
attain the same PFLB value (0 to 5) is significantly
smaller in the case of Examples 1 and 2. Also, when
comparing Comparative Examples 6 and 7 with Examples 5
and 6, it is seen that Example 5 and 6 exhibit a
significantly lower PFLB value when the same coating
amount (1.5 g/m2) is used.
As has been described above, the present invention
provides a cigarette paper exhibiting superior reduced
ignition propensities.
