The present invention relates to a cigarette that permits at least six puffs in spite of its short rod length of tobacco section.
In order to prevent a fire and to suppress sidestream smoke or to prevent carbon dioxide gas generation, a cigarette is proposed having a cut tobacco rod with a short length. For example, Japanese Utility Model No. 3049857 discloses a cigarette the length of which cut tobacco rod is half that of the ordinary cigarette in order to lower the amount of carbon dioxide generated per cigarette. Also Jpn. Pat. Appln. KOKAI No. 7-327654 discloses a cigarette the length of which cut tobacco rod is decreased to 1 to 1.5 cm in order to prevent a fire and to suppress the sidestream smoke. It should noted that a cigarette available on the market provides six to ten puffs under the standard smoking condition (ISO), while such a cigarette having a short cut tobacco rod provides puffs considerably smaller than that provided by the cigarette available on the market, which fails to satisfy smokers.
Further, Japanese Patent No. 2834325 discloses a cigarette in which a cut tobacco density is set at 300 mg/cc or more in order to decrease a combustion rate of the cut tobacco rod, thereby increasing the number of puffs provided by the cigarette. It may be possible for the cigarette of this type to provide a reasonable number of puffs even if the length of the cut tobacco rod is decreased. However, the cigarette having a cut tobacco density not lower than 300 mg/cc is not adapted for high-speed production. In addition, the cigarette of this type is substantially equal to the cigarette available on the market in the amount of ash per puff.
An object of the present invention is to provide a cigarette wrapper that permits lowering a spontaneous combustion rate, and to provide a novel cigarette that permits providing the number of puffs satisfactory to smokers in spite of its short length of cut tobacco rod, that is smaller than the conventional cigarette in the amount of ash and sidestream smoke per cigarette and that is economical and harmless to the earth environment.
A cigarette wrapper according to the present invention has a basis weight of 17 to 21 g/m2, a mixing ratio of a calcium carbonate filler of 16 to 25% by weight and a calcium carbonate content of 3 g/m2 or more.
According to the present invention, there is provided a cigarette in which cut tobacco is wrapped with the above cigarette wrapper.
To be more specific, a cigarette of the present invention comprises a tobacco section in which cut tobacco is wrapped with a cigarette wrapper, a filter section connected to one end of the tobacco section, and a tip paper integrally connecting the tobacco section to the filter section in a manner to cover the proximal end portion of the tobacco section and the filter section and provided with ventilation holes formed in a circumferential direction in positions apart from the smoking end of the filter section; wherein the tobacco section has a rod length of 30 to 46 mm and a cut tobacco filling density of 180 to 270 mg/cm3; and wherein the cigarette wrapper has a basis weight of 17 to 21 g/m2, a mixing ratio of a calcium carbonate filler of 16 to 25% by weight and a calcium carbonate content of 3 g/m2 or more; and wherein the cigarette provides at least six puffs under the standard smoking condition.
The present inventors have analyzed various factors such as cigarette wrappers, pore sizes of filters and air permeation resistance of cigarettes in smoking in an attempt to shorten the length of cut tobacco rod. As a result, it has been found that, in the case of combining materials used for manufacturing ordinary cigarettes and employing a standard cut tobacco density, the number of puffs provided by the cigarette is decreased if the length of cut tobacco rod is short, resulting in failure to satisfy smokers. It has been found that, the standard cut tobacco density brings about a high spontaneous combustion rate of the cigarette, i.e., a combustion rate of the cut tobacco rod under the state that the cigarette is not smoked, resulting in decrease in the number of puffs. Therefore, it was expected that at least six puffs per cigarette, which was satisfactory to smokers, would be achieved, if it would be possible to lower the spontaneous combustion rate of the cigarette.
The present invention provides a novel cigarette wrapper that permits lowering the spontaneous combustion rate of the cigarette, and a cigarette prepared by using the particular cigarette wrapper.
The present inventors have found that, for lowering the spontaneous combustion rate of the cigarette, it is effective to use a cigarette wrapper not containing a combustion improver and having a small basis weight and a small weight ratio of the filler (calcium carbonate). It should be noted that, in order to roll cut tobacco with the ordinary cigarette-making machine, it is desirable for the cigarette wrapper to have a tensile breaking load in the vertical direction of 1.0 kg/15 mm to 2.0 kg/15 mm. It has been found, however, that, if the basis weight of the cigarette wrapper is excessively small, the tensile breaking load is rendered smaller than 1.0 kg/15 mm, and that, if the content of the filler is excessively decreased, the tensile breaking load of the cigarette wrapper is caused to exceed 2.0 kg/15 mm as well as a burning cigarette is spontaneously extinguished.
Based on the findings, the present inventors have developed a cigarette wrapper having a basis weight of 17 to 21 g/m2, a mixing ratio of a calcium carbonate filler of 16 to 25% by weight and a calcium carbonate content of 3 g/m2 or more.
The present inventors have also developed a cigarette having a rod length of 33 to 46 mm and a cut tobacco filling density of 180 to 270 mg/cm3, and providing at least six puffs under the standard smoking condition, by using a cigarette wrapper having a basis weight of 17 to 21 g/m2, a mixing ratio of a calcium carbonate filler of 16 to 25% by weight and a calcium carbonate content of 3 g/m2 or more. The cigarette of the present invention has a cut tobacco filling density within a standard range of 180 to 270 mg/cm3 and a shot rod length of 30 to 46 mm, more preferably 35 to 42 mm, and yet permits at least six puffs under the standard smoking condition.
In the present invention, it is possible to provide cigarettes having various tar values matching with tastes for smokers by adjusting a filter section and a tobacco section.
For example, in the design of a high tar cigarette having a tar value in mainstream smoke of 6 mg or more, it is desirable to set the air flowing rate through the ventilation holes (Vf) in the filter section at 30% or less and to set the mixing ratio of expanded cut tobacco in the cut tobacco at 20% by weight or less.
The cut tobacco performs a function of lowering the temperature of smoke. In the cigarette of the present invention, however, the smoke temperature is unlikely lowered because the rod length of the tobacco section is short. In particular, the smoke temperature is unlikely lowered in the case where the Vf value is low, which possibly impairs the flavor. However, it is possible to improve the flavor by arranging a tip paper connecting the cut tobacco rod to the filter section such that the tip paper covers the proximal end portion of the cigarette wrapper over a length of 10 mm or more.
On the other hand, in the design of a low tar cigarette having a tar value in mainstream smoke of 6 mg or less, more desirably 3 mg or less, it is desirable to set the Vf value of the filter section at 50% or more and to set the mixing ratio of expanded cut tobacco in the cut tobacco at 20% by weight or more.
Also, since the smoke temperature is unlikely lowered in the cigarette of the present invention, if the filter section contains menthol, the high temperature smoke promotes evaporation of menthol. It follows that it is possible to provide a feeling of coolness in smoking more satisfactorily compared with an ordinary menthol cigarette.
Examples of the present invention will now be described.
Cigarettes were prepared by changing in various fashions the designs of the tobacco section, the cigarette wrapper and the filter section, as shown in Table 1. The tobacco section was controlled in respect of the type of cut tobacco, the rod length, the mixing ratio of expanded cut tobacco and the cut tobacco density. The cigarette wrapper was adjusted in respect of the basis weight, the calcium carbonate (CaCO3) content, the mixing ratio of the combustion improver, and the air permeability (in CORESTA units). The filter section was adjusted in respect of the type of filter, the length of the filter and the air flowing rate through the ventilation holes (Vf).
Table 1 shows three comparison groups, each including three examples. In each of comparison groups, a standard article representing a cigarette available on the market or a cigarette close to the cigarette available on the market, a reference article representing a cigarette having a cut tobacco rod shorter than that of the standard article. Examples 1 to 3 represent cigarettes of the present invention. To be more specific, in the cigarettes of Examples 1 to 3, the cigarette wrapper has a basis weight of 17 to 21 g/m2, the mixing ratio of the calcium carbonate filler of 16 to 25% by weight and the calcium carbonate content of 3 g/m2 or more, and the tobacco section has a rod length of 30 to 46 mm.
Table 2 shows the results of measurements of the air permeation resistance, the spontaneous combustion rate, the burned length, the spontaneous combustion time, the tar content in the mainstream smoke, the amount of the sidestream smoke, and the number of puffs in respect of each of the cigarettes that were tested. The combustion state of the cigarette was measured under the standard smoking condition (ISO).
As apparent from Table 2, the cigarette for each of Examples 1 to 3 exhibited a spontaneous combustion rate lower than that for the cigarette of the reference-article, provided at least six puffs in spite of the shorter rod length of the tobacco section, and was smaller in the amount of the sidestream smoke.
As described above in detail, the present invention provides a cigarette wrapper that permits lowering the spontaneous combustion rate, and provides a novel cigarette that permits the number of puffs satisfactory to smokers in spite of the shorter length of cut tobacco rod as well as permits decreasing the amount of ash and the amount of sidestream smoke per cigarette, compared with the conventional cigarette, and is economical and not harmful to the earth environment.