WO2001048315A1

WO2001048315A1 - Cigarette

Info

Publication number: WO2001048315A1
Application number: PCT/JP2000/009186
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: AU2223801A

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 0.38 Wm-1K-1 or less.

Description

Specification

Cigarette

Technical field

The present invention relates to a cigarette having a small air permeability of a wrapping paper and a high natural burning rate.

Background art

In recent years, there has been an increasing emphasis on designing cigarettes to suit smokers' preferences. For example, cigarettes with low tar, high natural combustion rate and high flavor are demanded.

Conventionally, to increase the natural burning rate of cigarettes, measures have been taken to increase the air permeability of the wrapping paper. However, if the wrapping paper has a high air permeability, the mainstream smoke per puff decreases, and it becomes difficult to design a cigarette according to the smoker's taste.

An object of the present invention is to provide a cigarette having a small air permeability of a wrapping paper and a large natural burning speed.

Disclosure of the invention

The cigarette of the present invention is a cigarette obtained by winding a cigarette by a wrapper, wherein the wrapper has an air permeability of 30 collector units or less and a thermal conductivity of 0.38 W. m-1 K- ¹ or less.

BRIEF DESCRIPTION OF THE FIGURES

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

Fig. 2 shows the temperature at the ignition point of the cigarette paper according to the present invention. FIG. 4 is a diagram showing the change as a parameter of the thermal conductivity of the wrapping paper.

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 state of natural combustion repeatedly ignites and extinguishes the wrapping paper, and combustion proceeds intermittently. This was made clearer by taking a video of the burning of the cigarette and graphing the change over time in the burning position of the cigarette paper. That is, when the wrapping paper is ignited, the burning position moves a little, but the wrapping paper extinguishes immediately and the burning position does not move for a while. I understood.

Such intermittent combustion of cigarettes is thought to be due to the following mechanism. When the cigarette is ignited, the cigarette burns with the tobacco shred and the burning position of the cigarette moves, but the cigarette shred which is not ignited at a certain distance from the ignition point of the tobacco shred At the point of contact, the fire extinguishes the wrapping paper, 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 reignites after the temperature of the wrapping paper gradually increases. Therefore, the burning rate differs depending on the time required for re-ignition of the fire 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 the burning of cigarettes, and until the fire extinguishing paper once re-ignited. Derive a theoretical equation that represents the temperature change of Was

Shows a cross section of a cigarette 10 schematically, and the cigarette 10 has a structure in which a cigarette cut 20 is wound with a wrapping paper 30. In Fig. 1, reference numeral 21 denotes the tobacco cut, reference 31 denotes the ignition point of the wrapping paper (the point where the fire is extinguished but reignition occurs at this time), and reference numeral 22 denotes the cigarette nick that contacts the ignition point of the paper. , Symbols 32 indicate rolled paper ash, respectively. The arrows in Fig. 1 indicate conduction or radiative heat transfer.

The time change of the temperature of the ignition point 31 of the wrapping paper is expressed by the following equation (1). The time change of the temperature of the tobacco cut 22 in contact with the paper ignition point 31 included in the expression (1) is expressed by the following expression (2).

+ τ · (1)

: _Ρ ρ) _ρ Δζ (Cpp) p Δζ · ζ ζ.

8 X _t 5 T _t

+ Seven τ-dt (Cpp) t dx (Cpp) tzz

so,

T: Temperature of rolled paper or rolled ash [K] t: time [s]

λ p: Thermal conductivity of roll paper or thermal conductivity of roll ash

[W m- ¹ K- 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]

f p: emissivity of roll paper or emissivity of roll ash [1]

σ: Stefan-Boltzmann constant ^{^{[W m "2 K" 4}} ]

Δ ：: Roll thickness or roll ash thickness [m]

T oo: Ambient temperature [K]

Φ _t p: Total absorption rate between tobacco cut and wrapping paper or ash [1] ：: Burning cut 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 p) _t : heat capacity of tobacco cut [J m -3]

∑ _t : Emissivity of tobacco cut [1]

Φ _tt : Total absorption rate between tobacco ticks [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 based on the radiant heat transfer from the outer surface of the cigarette to the outside (the second term on the right side), 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 of the wrapper to the tobacco cut 22 through the wrapper (term 4 on the right side) Means that Equation (2) indicates that the time change (left side) of the temperature of the tobacco cut 22 in contact with the paper ignition point 3 1 indicates that the conduction transfer from the burning tobacco cut to the tobacco cut 22 through the tobacco cut 2 2 The term due to heat (the first term on the right side), the term due to conduction heat transfer from the paper ignition point 31 to the tobacco cut 22 (the second term on the right side), and from the burning tobacco cut to the tobacco cut The term due to radiative heat transfer to tobacco cut 22 (the third term on the right side), and the conduction transfer to tobacco cut 20 on the cold side through tobacco cut from tobacco cut 22 This means that it is expressed as the sum of the terms due to heat (the fourth term on the right side).

In order to achieve the purpose of the present invention of increasing the natural burning rate (SBR) of a cigarette, the temperature change represented by the equations (1) and (2) must be changed over time. Should be increased.

Therefore, the present inventors calculated the effect of the temperature of the ignition point 31 of the wrapping paper on the time change by changing various parameters in the equations (1) and (2). I asked. At this time, no. The thermal conductivity, heat capacity and emissivity of the wrapping paper and wrapping paper ash were examined as parameters. As a result, to increase the natural burning rate (SBR) of a cigarette, either reduce the thermal conductivity of the paper wrap, increase the thermal conductivity of the paper ash, or increase the thermal conductivity of the paper ash. It was found that reducing the emissivity was most effective, and that changes in the heat capacity and emissivity of the wrapping paper and ash did not significantly affect the time change of the temperature.

Figure 2 shows the change over time of the ignition point 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 when the thermal conductivity of the wrapping paper is a standard value, and the solid line is the thermal conductivity of the wrapping paper. Calculation example when the conductivity is 20% lower than the reference example (— 20%). The dashed line indicates the case where the thermal conductivity of the wrapping paper is 20% higher than the reference example (+ 20%). This is a calculation example of. From this figure, it can be seen that by reducing the thermal conductivity of the wrapping paper, the temperature of the ignition point of the wrapping paper tends to rise over time (the natural combustion rate increases). I understand.

Figure 3 shows the temporal change of the ignition point temperature of the paper wrap, and the thermal conductivity of the paper ash as a parameter. In Fig. 3, the reference example is a calculation example in which the thermal conductivity of the paper ash is a standard value, and the solid line is a case in which the thermal conductivity of the paper ash is 20% higher than the reference example (+20) %), And the dashed line is a calculation example when the thermal conductivity of the wrapping paper ash is 2 °% lower than the reference example (120%). From this figure, it can be seen that by increasing the thermal conductivity of the paper ash, the temperature of the ignition point of the paper wrap tends to rise with time (the natural combustion rate increases). Wakapuru.

Since the thermal conductivity of the wrapping paper and ash is not determined solely by the air permeability of the wrapping paper, a wrapping paper with low air permeability can be used. Therefore, according to the present invention, a paper roll having a low air permeability of 30 collector units or less and a thermal conductivity of 0.38 W m-1 K- ¹ or less is used. Cigarettes with a high natural combustion rate can be provided. Such a cigarette with low air permeability and high natural combustion rate has never been known before. In the present invention, the air permeability of the wrapping paper is preferably at least 0 core units, and the thermal conductivity of the wrapping paper is at least 0.1 Wm-1 K-1 and 0.38 Wm. -i K- ¹ or less, preferably between 0.2 and 0.37 W ΙΏ-1 K-1 is more preferable.

In the present invention, the following method can be considered as a specific method for reducing the thermal conductivity of the wrapping paper. (A) Increase the amount of filler in the wrapping paper. Since filler particles have the effect of reducing the thermal conductivity of the wrapping paper, increasing the amount of filler in the wrapping paper decreases the thermal conductivity of the wrapping paper. (B) Reduce the amount of fibers that make up the wrapping paper. Since the fiber has the effect of increasing the thermal conductivity of the wrapping paper, reducing the amount of fiber reduces the thermal conductivity of the wrapping paper. (c) The thermal conductivity of the wrapping paper is reduced by disturbing the degree of arrangement of the fibers constituting the wrapping paper. (D) Reduce the thermal conductivity of the wrapping paper by mixing a material with low thermal conductivity into the wrapping paper.

On the other hand, as a specific method for increasing the heat conduction of the paper ash, a method using a filler having a small particle size can be considered. When the wrapping paper containing the filler having a fine particle size turns into ash, the structure of the ash becomes finer and the heat conduction increases.

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

Hereinafter, examples of the present invention will be described.

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

The wrapping paper used has a basis weight of 30 g / m 2 and has no additive (combustion control agent). As the filler, calcium carbonate having an average particle diameter of 0.3 m was used. The air permeability of these wrappers is in the range of 0 to 20 core units [CU]. Paper roll The thermal conductivity of the paper and the thermal conductivity of the paper ash are as shown in Table 1.

On the other hand, 0.69 g of commercial blend having a density of 230 mg / cm ³ was used as the tobacco cut. Using these tobacco cuts and wrapping paper, cigarettes with an outer diameter of 8 mm were manufactured.

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

As is clear from Table 1, the cigarettes D to F according to the present invention reduce the thermal conductivity of the wrapping paper by increasing the blending ratio of the filler. Therefore, both low air permeability and high natural combustion rate are satisfied.

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

Claims

The scope of the claims

1. In a cigarette in which tobacco is wrapped around a cigarette paper, the cigarette paper has an air permeability of 30 collector units or less and a thermal conductivity of 0.38 W m-1 K- ¹ or less. A cigarette characterized by something.