Technical Field
[0001] The present invention relates to a low ignition propensity cigarette paper.
Background Art
[0002] 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
[0003] 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.
[0004] 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 found that the coating required to exhibit the same ignition
propensities differs depending on the degree of polymerization or viscosity of sodium
alginate.
[0005] 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.
[0006] 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/m
2, 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.
[0007] 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/m
2, 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.
[0008] According to a third aspect of the present invention, there is provided a low ignition
propensity cigarette paper comprising base cigarette paper containing a filler in
an amount of 2 g/m
2 or more, and having a basis weight exceeding 22 g/m
2 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/m
2, 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
[0009]
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
[0010] The present invention will be explained in more detail.
[0011] 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.
[0012] 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 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/m
2 or more. The filler may be contained in an amount of 2 to 8 g/m
2 in the base cigarette paper. The base cigarette paper usually has a basis weight
exceeding 22 g/m
2. The basis weight is usually 80 g/m
2 or less and preferably more than 20 g/m
2 but 28 g/m
2 or less. The inherent air permeability of the base cigarette paper is usually 30
to 60 CORESTA units.
[0013] 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.
[0014] 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 they
are arranged in the form of plural circular bands apart from one another in the longitudinal
direction of the tobacco rod.
[0015] In the present invention, sodium alginate is used as the burn limiting agent. Alginic
acid is polyuronic acid consisting of two types of monomers, β-D-mannuronic acid and
α-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.
[0016] Generally, the total coating amount (dry basis) of the sodium alginate burn limiting
agent is less than 3g per m
2 of the coating area. A coating amount of as low as 0.2 to 2 g/m
2 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 paper) exhibiting a percent full-length burn (PFLB) of 0 to 10% when
measured according to ASTM E-2187-04.
[0017] A cigarette paper according to one embodiment of the invention includes base cigarette
paper containing a filler in an amount of 2 g/m
2 or more and having a basis weight exceeding 22 g/m
2 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/m
2. 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.
[0018] 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.
[0019] 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.
[0020] 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 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) 11b of the tobacco rod 11 by using a tipping paper 17
according to an ordinary method.
[0021] 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.
[0022] 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 µm. The spacing between the adjacent burn limiting areas 14 is
preferably 18 mm to 25 mm.
[0023] In the cigarette illustrated in FIG. 1, no burn limiting agent is applied to an area
16 at a distance d 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 11a 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.
[0024] Now, when the cigarette 10 is ignited at the distal end 11a 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.
[0025] The present invention will be explained by way of Examples, which are, however, not
intended to be limiting of the invention.
[0026] Examples 1 to 6 and Comparative Examples 1 to 9.
[0027] First, the polymerization degree and viscosity of 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-1, ALG-2, ALG-3, ALG-4 and ALG-5 are available under the tradenames of ULV, IL-2,
I-1, I-5 and I-S, respectively.
[0028] 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.
[0029] 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 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 m
2 of the area to which the burn limiting agent (sodium alginate) 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/m
2 because the coating amount should be multiplied by 7/27.
[0030] 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.
[0031] 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>
[0033] 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.
[0034] 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 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.
[0035] 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 symbol of sodium alginate |
Polymerization degree of alginic acid (Number of monomers) |
Viscosity (cP) |
ALG-1 |
30-180 |
900 |
ALG-2 |
250-400 |
4700 |
ALG-3 |
550-580 |
19800 |
ALG-4 |
650-670 |
30000 |
[Table 2]
Table 2:
Examples |
Base cigarette paper |
Burn limiting agent |
Coating amount of burn limiting agent (g/m2) |
PFLB (%) |
Amount of filler (g/m2) |
Basis weight (g/m2) |
Amount of burn adjusint agent (% by weight) |
Air permeability (C.U.) |
Comp. Ex. 1 |
7.7 |
25.5 |
0.3 |
35.2 |
None |
- |
100 |
Comp. Ex. 2 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-1 |
3.6 |
0-5 |
Comp. Ex. 3 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-2 |
2.8 |
0-5 |
Comp. Ex. 4 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-1 |
3 |
40-60 |
Comp. Ex. 5 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-2 |
2.1 |
40-60 |
Comp. Ex. 6 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-1 |
1.5 |
80-100 |
Comp. Ex. 7 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-2 |
1.5 |
70-80 |
Example 1 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-3 |
2 |
0-5 |
Example 2 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-4 |
1.4 |
0-5 |
Example 3 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-3 |
1.8 |
40-60 |
Example 4 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-4 |
1.2 |
40-60 |
Example 5 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-3 |
1.5 |
50-70 |
Example 6 |
7.7 |
25.5 |
0.3 |
35.2 |
ALG-4 |
1.5 |
0-5 |
[0036] 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/m
2) is used.
[0037] As has been described above, the present invention provides a cigarette paper exhibiting
superior reduced ignition propensities.
1. 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.
2. The cigarette paper according to claim 1, wherein a basis weight of the base cigarette
paper is 80 g/m2 or less.
3. 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.
4. The cigarette paper according to claim 3, wherein a basis weight of the base cigarette
paper is 80 g/m2 or less and the viscosity of the sodium alginate is 40000 cP or less.
5. A low ignition propensity 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.
6. The cigarette paper according to claim 5, wherein the filler is contained in an amount
of 8 g/m2 or less in the base cigarette paper and the sodium alginate is applied to the base
cigarette paper in an amount of 0.2 to 2 g/m2.
7. The cigarette paper according to claim 1, wherein the burn limiting areas are in a
form of plurality of stripes which extend in a longitudinal direction of the tobacco
rod and are apart from one another in a circumferential direction of the tobacco rod,
when the cigarette paper wraps a tobacco rod.
8. The cigarette paper according to claim 3, wherein the burn limiting areas are in a
form of plurality of stripes which extend in a longitudinal direction of the tobacco
rod and are apart from one another in a circumferential direction of the tobacco rod,
when the cigarette paper wraps a tobacco rod.
9. The cigarette paper according to claim 5, wherein the burn limiting areas are in a
form of plurality of stripes which extend in a longitudinal direction of the tobacco
rod and are apart from one another in a circumferential direction of the tobacco rod,
when the cigarette paper wraps a tobacco rod.
10. The cigarette paper according to claim 1, wherein the burn limiting areas are in a
form of plurality of circular bands which extend in the circumferential direction
of the tobacco rod and are apart from one another in the longitudinal direction of
the tobacco rod, when the cigarette paper wraps a tobacco rod.
11. The cigarette paper according to claim 3, wherein the burn limiting areas are in a
form of plurality of circular bands which extend in the circumferential direction
of the tobacco rod and are apart from one another in the longitudinal direction of
the tobacco rod, when the cigarette paper wraps a tobacco rod.
12. The cigarette paper according to claim 5, wherein the burn limiting areas are in a
form of plurality of circular bands which extend in the circumferential direction
of the tobacco rod and are apart from one another in the longitudinal direction of
the tobacco rod, when the cigarette paper wraps a tobacco rod.
13. A cigarette paper according to claim 1, which provides a cigarette exhibiting a PFLB
value of 0 to 10% when measured according to ASTM E-2187-04.
14. A cigarette paper according to claim 3, which provides a cigarette exhibiting a PFLB
value of 0 to 10% when measured according to ASTM E-2187-04.