WO2001048317A1

WO2001048317A1 - Cigarette

Info

Publication number: WO2001048317A1
Application number: PCT/JP2000/009195
Authority: WO
Inventors: Keigo Miura
Original assignee: Japan Tobacco Inc.
Priority date: 1999-12-27
Filing date: 2000-12-25
Publication date: 2001-07-05
Also published as: AU2401901A

Abstract

A cigarette prepared by wrapping shredded tobacco with a wrapping paper, characterized in that the wrapping paper has a permeability of 30 Coresta Units or less and a thermal conductivity of 0.40 Wm-1K-1 or less.

Description

Specification

Cigarette

Technical field

The present invention relates to a cigarette in which the wrapping paper has a high air permeability and a low natural burning rate.

Background art

In recent years, reducing sidestream smoke from cigarettes has become a major issue. Also, if the burning of cigarettes can be reduced between the knobs, the tobacco shreds can be used efficiently. Therefore, for these purposes, it has been considered to reduce the natural burning rate (SBR) of cigarettes.

Conventionally, to reduce the natural burning rate of cigarettes, measures to reduce the air permeability of the wrapping paper or to add a combustion regulator to the wrapping paper have been studied.

However, if the air permeability of the wrapper is low, the mainstream smoke per puff is large, making it difficult to design cigarettes to suit the smoker's taste and resulting from combustion. There are also health problems because the diffusion of gas components such as CO is suppressed.

By increasing the ventilation ratio (V f) from the ventilation holes provided in some of the filter paper, some of the mainstream smoke per puff is used. Can reduce CO2 and promote CO diffusion, but there is a limit to controlling these characteristics by adjusting Vf.

An object of the present invention is to provide a cigarette in which the wrapping paper has a high air permeability and a low natural combustion speed. Disclosure of the invention

The cigarette of the present invention is a cigarette obtained by winding a cigarette wrap by wrapping paper, wherein the wrapping paper has an air permeability of 30 collector units or more and a thermal conductivity of 0.4 OW m. -l K-1 or more.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is an explanatory diagram showing the state of conduction heat transfer and heat dissipation heat transfer in a cross section of a cigarette.

FIG. 2 is a diagram showing the time change of the temperature of the ignition point of the cigarette paper of the cigarette according to the present invention with the thermal conductivity of the cigarette paper as a parameter.

FIG. 3 is a diagram showing the time change of the temperature of the ignition point of the cigarette paper of the cigarette according to the present invention with the thermal conductivity of the paper ash as a parameter.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail.

The present inventors have found that a cigarette in a natural combustion state repeats ignition and extinguishing of wrapping paper, and combustion proceeds intermittently. This was made clearer by taking a video of the burning of cigarettes and graphing the change over time in the burning position of the cigarette paper. In other words, it was found that when the wrapping paper ignites, the combustion position moves a little, but the wrapping paper extinguishes the fire immediately and the combustion position repeats if the combustion position does not move for a while.

It is thought that such intermittent combustion of cigarettes is due to the following mechanism. When the cigarette is ignited, the wrapping paper burns with the tobacco cut and the burning position of the wrapping paper moves, but at a position some distance from the ignition point of the tobacco cut The wrapping paper extinguishes at the point of contact with the non-ignited tobacco cut, and the burning position of the wrapping paper does not move for a while. The burning cigarette is used as a heat source, and the wrapping paper is re-ignited after the temperature of the wrapping paper gradually increases. Therefore, the burning rate depends on the time required for re-ignition of the extinguishing paper, and this phenomenon is considered to be the rate of heat transfer.

Therefore, as shown in Fig. 1, the present inventors considered various parameters contributing to cigarette combustion and considered that the fire extinguisher once fired was re-ignited. A theoretical equation representing the temperature change was derived.

FIG. 1 schematically shows a cross section of a cigarette 10. The cigarette 10 has a structure in which a cigarette cut 20 is wound around a cigarette paper 30. In Fig. 1, reference numeral 21 denotes a burning tobacco cut, reference numeral 31 denotes a cigarette ignition point (the point where the fire is extinguished but reignition occurs at present), reference numeral 22 denotes a cigarette cut in contact with the cigarette ignition point, Numerals 32 indicate rolled paper ash, respectively. The arrows in Fig. 1 indicate conduction or radiative heat transfer.

The change over time of the ignition point 31 of the wrapping paper is expressed by the following equation (1). Further, the time change of the temperature of the tobacco cut 22 in contact with the wrapping paper ignition point 31 included in the equation (1) is expressed by the following equation (2). δτ λ δ ² Τ ε _ρ σ

dt (Cpp) p dx ² (CpP) _p Az

+ (1)

here,

T: Temperature of rolled paper or rolled ash [κ]

t: time [s]

λ ρ: Thermal conductivity of paper wrap or thermal conductivity of paper ash

[W m- ¹ Κ- ¹ ]

(C pp) _p : Heat capacity of roll paper or heat capacity of roll ash [J m -3] x: Displacement in tobacco rod direction [m]

epsilon p: emissivity of the emissivity or the wrapper ash wrapping paper [One] σ: Stefan-Boltzmann constant ^{^{[W m "2 K" 4}} ]

Δ z: Paper roll thickness or paper roll ash thickness [m]

T _∞: ambient temperature [K] tp: overall absorption rate of between cut tobacco and卷紙or the wrapping paper ash [One]

Θ: Combustion temperature [K]

z z: Tobacco cut thickness [m]

T _t : Tobacco temperature [K] λ _t : Tobacco cut thermal conductivity [W m-1 K- ¹ ]

(C pp) _t : heat capacity of the tobacco cut [J m-3]

ε _t ^: Emissivity of tobacco cut [1]

Φ _tt : The overall absorption rate between tobacco cuts [1].

In equation (1), the time change (left side) of the temperature of the ignition point 31 of the paper roll is due to the heat transfer from the tobacco cut 21 to the paper ignition point 31 through the paper ash 32. (The first term on the right side), the term due to radiant heat transfer from the outer surface of the cigarette to the outside (the second term on the right side), the radiative transfer from the burning tobacco cut 21 to the ignition point 31 of the paper roll The sum of the term due to heat (term 3 on the right side) and the term due to heat transfer from the ignition point 31 to the tobacco cut 22 through the wrapping paper (term 4 on the right side) Means that

Equation (2) shows that the temperature change (left side) of the tobacco cut 22 in contact with the paper ignition point 3 1 is the heat transfer from the burning tobacco cut to the tobacco cut 2 through the tobacco cut 2 2. (The first term on the right side), the term due to the heat transfer from the ignition point 31 to the tobacco section 22 (the second section on the right side), and the tobacco section from the burning tobacco section through the tobacco section. The term due to radiative heat transfer to step 22 (the third term on the right side) and the conduction heat transfer from tobacco step 22 to the tobacco step 20 on the cold side through the tobacco step. (The fourth term on the right-hand side).

If the natural burning rate (SBR) of the cigarette is reduced, the objective of the present invention is achieved by changing the temperature over time expressed by the equations (1) and (2). Should be small.

Therefore, the present inventors have determined that various expressions in the expressions (1) and (2) By changing the parameters, the effect of the ignition point 31 of the wrapper on the temperature over time was calculated. At this time, the thermal conductivity, heat capacity and emissivity of the wrapping paper and wrapping paper ash were examined as parameters. As a result, to reduce the natural burning rate (SBR) of cigarettes, either increase the thermal conductivity of the wrapper or reduce the thermal conductivity of the ash. It is most effective to increase the emissivity of the wrapping paper, and the change in the heat capacity of the wrapping paper / wrapping ash does not significantly affect the time change of the temperature. I got it.

Figure 2 shows the change over time of the ignition point temperature of the wrapping paper, and the thermal conductivity of the wrapping paper as a parameter. In Fig. 2, the reference example is a calculation example in which the thermal conductivity of the wrapper is a standard value, and the solid line is a case in which the thermal conductivity of the wrapper is 20% lower than the reference example (20%). The dashed line is a calculation example when the thermal conductivity of the wrapping paper is 20% higher than the reference example (+ 20%). From this figure, it can be seen that by increasing the thermal conductivity of the wrapping paper, the temperature of the ignition point of the wrapping paper is less likely to rise with time (the natural combustion rate decreases). I understand.

Fig. 3 shows the change over time of the ignition point of the wrapping paper with the thermal conductivity of the wrapping paper as a parameter. In Fig. 3, the reference example is a calculation example when the thermal conductivity of the paper ash is a standard value, and the solid line is a case where the thermal conductivity of the paper ash is 20% higher than the reference example (+2 The dashed line is a calculation example when the thermal conductivity of the wrapping paper ash is 20% lower (120%) than the reference example. From this figure, it can be seen that the thermal conductivity of the paper ash is reduced to reduce the temperature of the ignition point of the paper. Is difficult to rise with time (the natural combustion speed decreases).

Since the thermal conductivity of the wrapping paper and ash is not determined only by the air permeability of the wrapping paper, it is possible to use a wrapping paper having a high air permeability. Therefore, according to the present invention, a wrapping paper having a high air permeability, 30 collector units or more, and a thermal conductivity of 0.40 Wm-1K-1 or more is obtained. It can be used to provide cigarettes with low natural combustion rate. Such cigarettes with high air permeability and low natural combustion rate have not been known before. The Te present invention odor, air permeability of the paper wrapper 2 0 0 Collector scan and data units Ru der less This is rather preferred, the thermal conductivity of the wrapping paper 0 EWM -. And ¹ or less der Ru this - i K Is preferred.

In the present invention, as a specific method for increasing the thermal conductivity of the wrapping paper, the following method can be considered. (A) Decrease the amount of filler in the wrapping paper. Since filler particles have the effect of reducing the thermal conductivity of the wrapping paper, reducing the amount of filler in the wrapping paper increases the thermal conductivity of the wrapping paper. (B) Increase the amount of fibers that make up the wrapping paper. Since fibers have the effect of increasing the thermal conductivity of the wrapping paper, increasing the amount of fibers increases the thermal conductivity of the wrapping paper.

(c) The thermal conductivity of the wrapping paper is increased by uniformly arranging the fibers constituting the wrapping paper to strengthen the web structure. (D) Mix materials with high thermal conductivity (for example, metal or graphite) into the wrapping paper to increase the thermal conductivity of the wrapping paper.

On the other hand, as a specific method for reducing the heat conduction of the paper ash, the particle size, which is usually used, is used instead of the filler in the sub-micron mouth. In addition, a method using a filler having a coarse particle size (for example, a particle size of 1 μm or more) can be considered. When the wrapping paper containing the coarse-particle filler becomes ash, the structure of the ash becomes coarser and the heat conduction is reduced.

Further, as a method of increasing the emissivity of the wrapping paper, a method of forming a particle layer having a high emissivity on the surface of the wrapping paper can be considered.

Hereinafter, examples of the present invention will be described.

The cigarettes A to E shown in Table 1 were designed. Cigarettes A to C are conventional ones, and cigarettes D and E relate to the present invention.

The wrapping paper used has a basis weight of 30 g / m ² and does not contain any additives (combustion control agents). As the filler, calcium carbonate having an average particle size of 0.3 μm was used, and the mixing ratio of the filler was adjusted within a range of 10 to 30%. The air permeability of these wrappers is in the range of 10 to 60 collector units [CU]. The thermal conductivity of the wrapping paper and the thermal conductivity of the wrapping ash are as shown in Table 1.

On the other hand, tobacco shreds were filled using a commercial blend at a packing density of 230 mg / cm 3. Using these tobacco cuts and wrapping paper, a cigarette with an outer diameter of 8 mm was manufactured.

Table 1 shows the results of measuring the natural burning rate (SBR) of cigarettes A to E under the standard smoking condition (ISO).

As is clear from Table 1, the cigarettes D and E according to the present invention increase the thermal conductivity of the wrapping paper by reducing the blending ratio of the filler. It satisfies both high air permeability and low natural combustion rate. Therefore, in the cigarette of the present invention, the ventilation ratio (V 通気) from the ventilating hole provided in the tip por- tion of the fin- olator section can be increased. In particular, reduction of mainstream smoke per puff and promotion of diffusion of gaseous components such as carbon dioxide can be realized.

As described above in detail, according to the present invention, it is possible to provide a cigarette in which the wrapping paper has a high air permeability and a low natural combustion rate.

Claims

The scope of the claims

1. For cigarettes in which tobacco cuts are wound by wrapping paper, the wrapping paper has an air permeability of 30 collector units or more and a thermal conductivity of 0.40 W m-1 K- ¹ or more. A cigarette characterized in that: