JPH11318421A - Cigarette filter with high filtration rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cigarette filter intended for low-tar cigarettes <=3 mg in tar levels and sufficiently affording feeling of satisfaction for smoking enjoyment such as smoking flavor and feeling of smoke level without impairing smoking taste. SOLUTION: This cigarette filter is such one as to comprise a filter section 2 composed of a core portion 2a at the center and a sheath portion 2b provided therearound; wherein, as for the core portion 2a, air flow rate therethrough is lower than the case with the sheath portion 2b, the air flow rate through the core portion 2a is <=30 cm/s when the filter section 2 is sucked at 17.5 ml/s, and tar filtration rate is >=80%, and the proportion of the cross section of the core portion 2a to that of the filter section 2 is 20-70%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cigarette filter for smoking, and more particularly to a cigarette filter having a tar value of 3 m per cigarette.
The present invention relates to a tobacco filter for low tar tobacco having a filtration rate of not more than g.

[0002]

2. Description of the Related Art Tobacco smokers have a tendency to shift from high tar tobacco to medium tar tobacco, from medium tar tobacco to low tar tobacco, and further to ultra-low tar tobacco in accordance with recent health trends. Such ultra-low tar tobacco is not more than 3 mg / tar, and furthermore,
About 1 mg / tobacco is commercially available. Early ultra-low tar tobacco increased air inflow from the tipping paper. For this reason, a feeling of responsiveness was not often obtained. Recently, ultra-low tar cigarettes have been developed that use a wrapping paper in consideration of flammability or a filter with a devised structure to emphasize the feeling of softness.

[0003] The following proposals have been made for filters with devised filter structures. JP 58
Japanese Patent Application Laid-Open No. 198284/1990 discloses a double concentric filter comprising a core for filtering cigarette smoke, an inner sleeve mounted around the core, and an air-permeable material provided around the inner sleeve. A filter comprising a sleeve body comprising This filter is used by attaching a breathable jacket around the sleeve body. In cigarettes using this filter, during smoking, most of the smoke is sent to the mouth of the smoker through the core portion, and most of the air that has passed through the breathable jacket is absorbed by the breathable jacket. To the smoker's mouth along the area between the and the sleeve. In this way, smoke and air are separately flowed in the filter and mixed in the smoker's mouth, thereby improving the taste. However, the mere separation of the smoke and the permeated air does not provide a satisfactory flavor and a sufficient amount of smoke.

JP-A-59-135879 discloses a dual-type filter for tobacco, in which a filter medium containing a flavoring agent and having a small airflow resistance is disposed at the center thereof, and a filter medium having a high airflow resistance is provided around the filter medium. A first filter part having a concentric two-layer structure is provided on the tobacco side,
A filter is disclosed in which a second filter portion provided with a plurality of grooves through which air flows along the longitudinal direction on the outer peripheral surface of a filter medium is provided on the suction side. When this filter is used, by the action of the groove through which the air flows and the filter medium having a small airflow resistance containing the flavor, a low tar,
It is possible to obtain richly flavored tobacco while having low gas. However, the flavor was obtained by flavoring, and was different from the original flavor due to the burning of tobacco leaves.

[0005] Japanese Patent Application Laid-Open No. 6-269270 discloses a double concentric filter having a central portion obtained by converging a corrugated paper core into a cylindrical shape and an outer peripheral portion made of cellulose acetate tow provided around the central portion. A filter having a configuration in which a part is wrapped with plug wrapping paper is disclosed. This filter is for low tar tobacco, and aims to improve taste while suppressing an increase in airflow resistance. However, although high filtration efficiency can be expected,
The taste during smoking was not fully satisfactory. Japanese Patent Application Laid-Open No. Hei 8-191682 discloses a sheath-core type including a core portion formed by converging a corrugated sheet processed into a corrugated shape, and a sheath portion provided around the core portion and formed by converging a fiber tow. in the filter, the airflow resistance of the core portion 500mmH ₂ 0 or more, there is disclosed that the ratio of the flow resistance of the core 2.5 times or more with respect to air flow resistance of the sheath portion. In this proposal, smoke density after passing through a filter is defined as an index for determining taste. It is disclosed that the smoke density after passing through the core portion is made higher than the smoke density after passing through the sheath portion to improve the taste. However, it has been difficult to apply to low tar tobacco having a tar value of 3 mg or less.

[0006]

As described above, various proposals have been made. However, in conventional low-tar cigarettes having a tar content of 3 mg or less, the original taste of cigarettes and the sense of smoke that the smoker perceives are sufficiently satisfied. It was difficult to do.
In the first place, in low tar tobacco, the absolute amount of smoke particles such as nicotine and tar in tobacco smoke inhaled by smokers is reduced by improving the filtration function of the filter, or by introducing external air. It is inevitable that the satisfaction of smoking is reduced because the tar is reduced by reducing the amount of tar. In addition, a filter made of paper, pulp, or the like as a filter material and simply having a high filtering action has a problem that the taste is spicy and easy to feel. The present invention has been made in view of the above circumstances and provides a tobacco filter which is excellent in high filterability without impairing the taste, even if it is a tobacco filter suitable for low tar tobacco having a tar value of 3 mg or less. That is the task.

[0007]

In order to solve the above-mentioned problems, the present invention proposes the following solutions. That is, the present invention is a tobacco filter having a high filtration rate for low tar tobacco having a tar value per tobacco of 3 mg or less, and has a core portion provided at the center and a sheath portion provided around the core portion. A filter section, wherein the core section has a lower flow rate of permeating air than the sheath section, and the filter section has a flow rate of 17.5 ml / s.
The flow rate of air passing through the core portion when suctioned by ec is 30 cm / sec or less, the filtration rate of tar is 80% or more, and the cutoff of the core portion with respect to the cross-sectional area of the filter portion. A tobacco filter having a high filtration rate, characterized in that the area ratio is 20 to 70%. The ratio of the reduced ventilation resistance of the core portion to the reduced ventilation resistance of the sheath portion is preferably 1.5 to 4. Further, the nicotine filtration rate is preferably 70 to 90%. The weight ratio of the core to the filter is preferably 45 to 70%. The airflow resistance of the filter unit is 100 to 170.
mmH ₂ O is preferred. The airflow resistance of the core is 500
~1000mmH ₂ O is preferred. Further, the filter ventilation rate is preferably from 60 to 80%. Also, a roll paper wound around the filter portion and a tip paper wound on the roll paper are provided.
It is preferably CU. In addition, a roll paper wound around the filter portion, and a tip paper wound on the roll paper, the tip paper,
It has an opening provided along its outer periphery for introducing ventilation air, and the ratio of the nicotine filtration rate after the opening to the nicotine filtration rate before the opening is 70%.
It is preferable that it is 90%. It is preferable that the sheath part is made of a fiber tow. Preferably, the core portion is formed by converging a corrugated sheet. It is preferable that one or both of the core part and the sheath part are made of cellulose acetate fibers.

[0008]

1 and 2 show an example of a tobacco filter (hereinafter abbreviated as a filter) according to the present invention. FIG. 1 is a cross-sectional view cut in a direction perpendicular to the axial direction. FIG. 2 is a side sectional view cut in parallel to the axis direction. The filter 1 has a schematic configuration including a filter chip including a cylindrical filter portion 2 and a gas-permeable wrapping paper 3 wrapped around the outer periphery of the filter portion 2, and a tip paper 4 wrapped over the wrapping paper 3. Have been.

The filter section 2 has a core section 2a provided at the center thereof, and a sheath section 2b provided around the core section 2a. The web 3 keeps the shape of the filter section 2 stable, and the filter section 2 and the web 3 have the same axial length. on the other hand,
As shown in FIG. 2, the tip paper 4 is
The length in the axial direction is longer than that of the web 3. One end of the tip paper 4 is aligned with the end of the filter chip in which the filter portion 2 and the web 3 are integrated, and the other end is a cigarette body (tobacco winding portion) 5.
By being attached to the end of a, the filter 1 is integrated with the tobacco main body 5a, and the tobacco 5 is configured.

The chip paper 4 is provided with a plurality of openings (holes) 4a along its outer periphery. External air (ventilation air) is taken into the filter 1 as needed from the opening 4a, so that a ventilating effect can be obtained.

The outer diameter of the filter section 2 is usually 7.8 mm. The length of the filter portion 2 and the web 3 in the axial direction is usually 25 mm, and the length of the tip paper 4 in the axial direction is usually 32 mm. The openings 4a are provided in a line at a position usually 12.5 mm from the suction end face of the filter 1.

The core portion 2a has a structure as shown in FIG.
Corrugated sheet 6 formed by processing a sheet material made of a thermoplastic material into a wave shape and forming a plurality of continuous grooves.
Is converged by, for example, rounding or folding. Corrugated sheet 6 groove depth d
Is, for example, 0.2 to 2 mm. Further, the interval (pitch between grooves) p between adjacent grooves is set to 0.5 to 3 mm. When d is less than 0.2 mm or when p is less than 0.5 mm, the corrugation of the sheet becomes difficult because the waves are too fine. Further, when the distance d exceeds 2 mm, or when the distance p is 3
If it exceeds mm, it may be difficult to converge the corrugated sheet 6 to form the core portion 2a. The sheet width of the corrugated sheet 6 (the distance between the groove and the opposite side in the parallel direction) is 90 to 240 mm.
Outside this range, it may be difficult to configure the core 2a.

In the core portion 2a formed by converging the corrugated sheet 6, an appropriate gap is formed by the groove of the corrugated sheet 6, thereby forming a flow path for passing smoke. When smoke passes through the core portion 2a, a smoke particle component such as tar and nicotine distributed in the smoke collides with the corrugated sheet 6, thereby filtering the smoke particle component. Is obtained. In the filter 1, the core portion 2 a is obtained by simply converging the corrugated sheet 6. For example, the major axis diameter X is 4 to 7 mm, and the minor axis diameter Y is 2 to 4 mm.
mm. As another example, the core part 2a can be formed from a fiber tow, which is preferably opened. The tow is obtained by bundling and assembling a plurality of filaments. For example, the core portion 2a can be formed by opening the tow and converging the tow into a cylindrical shape.

The sheath portion 2b is preferably formed of a fiber material such as an opened fiber tow. For example, the sheath portion 2b is formed by opening the tow and converging the tow into a tubular shape. Also in the sheath portion 2b, a filtering function of trapping smoke particle components can be obtained. The web 3 has a thickness of, for example, 30 to 90 μm.
m, preferably 55 to 85 μm. The tip paper 4 has a thickness of, for example, 33 to 53 μm.

FIG. 4 (a) shows another example of the shape of the filter of the present invention. For example, when the corrugated sheet is converged to form the core portion 2a, at the same time as or after the convergence, The core portion 2a is formed into a cylindrical shape by, for example, melting an outer peripheral surface of the converged object by transmitting the heat through a thermoforming tool or the like. By doing so, the shape of the core portion 2a becomes uniform in the length direction, and the shape stability can be improved. Like the filter 1A, the one in which the shape stability of the core 2a is improved,
For example, even if the filling amount of the filter material constituting the sheath portion 2b is increased, the shape of the core portion 2a is hardly changed during the manufacture of the filter, so that the manufacturing stability can be improved. For this reason, the width of adjustment of the filling amount of the sheath portion 2b can be widened, and the degree of freedom in designing the final filter is widened. In addition, the beauty can be improved. Further, the cross-sectional shape of the core portion 2a is not particularly limited, and may be various shapes such as a star, a triangle, and a quadrangle as shown in FIGS.

Further, as shown in FIG.
a of a core part 2a
By improving the shape stability of the filter 1B, the filter 1B can be configured. The thickness of the web 3 ′ is, for example, 30 to
It is 90 μm, preferably 55 to 85 μm.

As the material forming the core portion 2a and the sheath portion 2b, a fiber material is suitable, and among them, cellulose acetate fiber is preferably used from the viewpoint of taste.
It is preferable to use a fiber tow made of cellulose acetate (cellulose acetate tow) as a filter material constituting the sheath portion 2b. More preferably, it is a long fiber crimped tow made of cellulose acetate. By using this, it is possible to obtain filters 1, 1A, and 1B having high filtration efficiency of smoke particle components and good flavor. As a filter material constituting the core portion 2a, a corrugated sheet obtained by corrugating a spread cellulose acetate tow or the like is used. Alternatively, a corrugated sheet obtained by corrugating a web (sheet-like material such as woven fabric and nonwoven fabric) made of cellulose acetate fiber can be used. These can be used alone or in combination. Alternatively, similarly to the sheath portion 2b, a cellulose acetate tow is also preferable, and a long fiber crimped tow made of cellulose acetate is more preferable.

The weight ratio of the core 2a to the filter 2 is desirably 45 to 70%. When the weight ratio of the core portion 2a is less than 45%, the filtering ability of the core portion 2a is insufficient, and it may be difficult to form a low tar tobacco having a tar value of 3 mg or less. Also, if it exceeds 70%,
The removal rate of the smoke particle component may be too high, and the taste may be reduced. When a sheet made of a fiber material is used as a corrugated sheet, the filtration efficiency can be increased by increasing the basis weight of the sheet.

The core 2 with respect to the cross-sectional area of the filter 2
The ratio of the cross-sectional area of a is 20 to 70%, preferably 40 to 70%.
60%. If it is less than 20%, the filtration efficiency is reduced, and it may be difficult to form a low tar tobacco. If it exceeds 70%, the air passing through the core portion 2a is diluted by ventilation air, and the taste may be reduced. That is, by designing in this range, smoke can be efficiently filtered without lowering the taste.

In the filters 1, 1A and 1B, the flow velocity of the air passing through the core 2a is reduced by the sheath 2b.
The ventilation resistance of each of the core portion 2a and the sheath portion 2b is adjusted so as to be slower. The flow rate of the air passing through the core 2a (hereinafter referred to as the flow rate of the core 2a) is 30
cm / sec or less, preferably 15 to 30 cm / sec
It is said. If it exceeds 30 cm / sec, the taste may be lacking. The flow rate of the air passing through the sheath 2b (hereinafter referred to as the flow rate of the sheath 2b) is preferably 40
５０50 cm / sec.

The flow rate of the core section 2a and the flow rate of the sheath section 2b are set by using the flow rate measuring device shown in FIGS. 8 and 9 to set the tobacco 5 in which the filter 1 and the tobacco body 5a are integrated. It means the value obtained from the measured flow rate at the time of suction at 5 ml / sec. The applicant of the present invention has
No. 304371 proposes an apparatus for measuring the smoke particle component passing through a filter for each part of the filter. The flow rate measuring devices shown in FIGS. 8 and 9 are configured using the device proposed in Japanese Patent Application Laid-Open No. 9-304371. FIG. 8 is an enlarged sectional view of a sample holder, and FIG. It is a schematic block diagram.

The flow rate measuring device is generally constituted by the sample holder 30, flow rate measuring sections 43a and 43b, and a suction device (not shown). As the flow rate measuring units 43a and 43b, for example, a laminar flow meter manufactured by Dyna Sciences can be used. Sample holder 3
0 has a first opening 31, a second opening 32, and a third opening 33. A tubular flow path dividing member 34 is inserted into and fixed to the second opening 32. Flow path dividing member 34 of sample holder 30 and first opening 3
Tubes 41a and 41b are connected to 1 respectively. Flow measurement units 43a and 43b are inserted in the middle of these tubes 41a and 41b, respectively. The tubes 41a and 41b are connected to the suction device connecting portion 4
2 and are connected to a suction device via the suction device connecting portion 42.

The channel dividing member 34 of the sample holder 30
The tip 34b of the filter tip is sharp, and is inserted into the end face of the filter portion 2 of the filter chip inserted from the third opening 33. As a result, the flow path of the air that has passed through the center of the filter unit 2 and the flow path of the air that has passed through the outer periphery thereof are divided into the inside and the outside of the flow path dividing member 34. . The inner diameter D of the distal end 34b of the flow path dividing member 34 corresponds to the outer diameter of the central portion. By changing the inner diameter D, the measurement range of the central portion and the outer peripheral portion of the filter section 2 can be freely changed. Can be set. The inside of the flow path dividing member 34 is a central portion permeated gas flow path 34 a through which the air transmitted through the central part flows, and the third opening 33 is provided outside the flow path dividing member 34.
An outer peripheral portion permeated gas flow path 31a through which the air that has passed through the outer peripheral portion flows is formed from to the first opening portion 31.

In measuring the respective flow rates of the core 2a and the sheath 2b, the flow path dividing member 34 having an inner diameter D equal to the outer diameter of the core 2a is used, and the sample holder 30 is used.
The tobacco winding is set, and suction is performed from the suction device through the tubes 41a and 41b at a suction speed of 17.5 ml / sec. Then, the air that has passed through the core portion 2a enters the tube 41a from the central portion permeated gas flow path 34a, and the flow rate is measured by the flow rate measuring section 43a. On the other hand, the air that has passed through the sheath portion 2 b is
From the tube 41b, and the flow rate is measured by the flow rate measuring unit 43b. Then, a value obtained by dividing the measured flow rate by the sectional area of each part according to the following equations 1 and 2 is defined as the flow velocity of the core 2a and the sheath 2b.

That is, the flow velocity of the core 2a is expressed by the following equation (1).
Shall be obtained from Vc = Mc / ((Dc / 2) ² × π) Equation 1 where the symbols in Equation 1 indicate the following. Vc: Flow rate of core part (cm / sec) Mc: Measured value of flow rate of core part (ml / sec) Dc: Diameter of core part (cm) The flow rate of sheath part 2b is obtained from the following equation (2). . Vs = Ms / ((Df / 2) 2 × π- (Dc / 2) 2 × π) ... Equation 2, however, the sign of the formula 2 indicates the followings. Vs: Flow rate of sheath section (cm / sec) Ms: Measured flow rate of sheath section (ml / sec) Df: Diameter of filter section (cm) Dc: Diameter of core section (cm)

The airflow resistance of each of the core portion 2a and the sheath portion 2b is measured as follows. First, the filter section 2 is connected to the sheath section 2b and the core section 2b.
a. The ventilation resistance of the core portion 2a is measured according to a method defined by the Coresta method by wrapping a cellophane tape around the separated core portion 2a, inserting the cellophane tape into a tube having the same inner diameter as the outer diameter of the core portion 2a. The ventilation resistance of the sheath portion 2b is defined by the Coresta method by inserting a rod made of a vinyl chloride resin having the same outer diameter as the outer diameter of the core portion 2a into a portion of the separated sheath portion 2b corresponding to the core portion 2a. Measure according to the method given.

In the present invention, the ventilation resistance of the filter section 2 is preferably 100 to 170 mmH ₂ O,
ventilation resistance of a is 500~1000mmH ₂ O are preferred. More preferably, the airflow resistance of the filter unit 2 is 1
40~160mmH a ₂ O, flow resistance of the core 2a is 600~850mmH ₂ O. By setting it in such a range, the smoke is transferred to the core portion 2a and the sheath portion 2b.
Can be appropriately dispersed. Further, it becomes easy to reduce the flow velocity of the core portion 2a.

The reduced airflow resistance is determined by the above-described method using the core portion 2a and the sheath portion 2b measured independently.
The value obtained when the diameter of the filter unit 2 is 7.8 mm is determined from the ventilation resistance of the filter unit according to the following Expressions 3 and 4. Rc = rc × (Dc ² / Df ² ) Expression 3 where the symbols in Expression 3 indicate the following. Rc: reduced ventilation resistance of core part (mmH ₂ O) rc: ventilation resistance of core part (mmH ₂ O) Dc: diameter of core part (mm) Df: diameter of filter part (7.8 mm) Rs = rs / ( (Df ² −Dc ² ) / Df ² ) Expression 4 where the symbols in Expression 4 indicate the following. Rs: Conversion ventilation resistance of the sheath portion (mmH ₂ O) rs: flow resistance of the sheath portion (mmH ₂ O) Df: filter with a diameter (7.8 mm) Dc: the core portion diameter (mm)

That is, the reduced airflow resistance of the core 2a is a value obtained by multiplying the airflow resistance of the core 2a by the ratio of the cross-sectional area of the core 2a to the cross-sectional area of the filter 2.
The reduced airflow resistance of the sheath 2b is a value obtained by multiplying the airflow resistance of the sheath 2b by the ratio of the cross-sectional area of the sheath 2b to the cross-sectional area of the filter 2. Usually, the diameter of the filter section 2 is 7.8 mm, and the circumference thereof is 24.
Since it is 6 mm, Df is 7.8 mm in the present invention. Hereinafter, the ratio of the reduced ventilation resistance of the core portion 2a to the reduced ventilation resistance of the sheath portion 2b is referred to as a reduced ventilation resistance ratio. In the present invention, the reduced ventilation resistance ratio is set to 1.5 to 4, preferably 1.5 to 2.5. By setting this range, the smoke transmission characteristics of the core portion 2a and the sheath portion 2b are properly set, and the smoke flowing out of the core portion 2a and the sheath portion 2
b can improve the balance of the smoke flowing out.

The airflow resistance and reduced airflow resistance of the core 2a are as follows:
Specifically, it can be changed by changing the following conditions. 1) Corrugated molding conditions (temperature, pressure, clearance,
(Speed) 2) Core part molding conditions (temperature, speed) 3) Filter material characteristics (for example, selection of tow type ^* ) * The characteristics of tow type are expressed by fineness (dpf value) / total denier. 4) Sheet opening width (when using a material that requires opening) 5) Amount of plasticizer to be attached after opening 6) Outer diameter of core portion

The airflow resistance and reduced airflow resistance of the sheath 2b can be changed according to conditions such as filter material characteristics, filter material filling amount, and plasticizer amount. The airflow resistance of the filter unit 2 can be changed according to the conditions affecting the airflow resistance of the core 2a and the sheath 2b.

The ventilation effect of taking in outside air from the opening 4a of the tip paper 4 into the interior of the filters 1, 1A, 1B is based on the external air entering through the opening 4a with respect to the amount of suction reaching the mouth of the smoker. It is expressed by a filter ventilation rate (hereinafter referred to as a ventilation rate) which is a ratio (volume%) of the amount. This ventilation rate can be adjusted by changing the air permeability between the web 3 and the chip paper 4 and the size and number of the apertures 4a. The ventilation rate was determined by the Coresta method NO. This is a value obtained by measuring according to 6.

In the present invention, the ventilation rate is
60-80% is desirable. At this time, it is preferable that the air permeability of the web 3 is 10,000 to 30000 CU, and the air permeability of the chip paper 4 is 1200 to 3600 CU. These air permeability is determined by the Coresta method NO. It is a value obtained by measuring according to 40. By setting the ventilation rate in the above range, the smoke passing through the core portion 2a is not diluted by the ventilation air, and the lack of taste can be reduced.

The nicotine filtration rate of the filters 1, 1A, 1B is preferably 70 to 90%. 70
%, It may be difficult to constitute a low tar tobacco. If it exceeds 90%, the taste may be impaired. The nicotine filtration rate can be measured based on the Cholesta method. The nicotine filtration rate is determined by the core 2a
It can be changed by adjusting the configuration of the material, the weight ratio, the cross-sectional area, etc. of the sheath portion 2b and the ventilation rate. Also, the cigarette body 5a side is in front,
Tip paper 4
The nicotine filtration rate of the filter section 2 after the opening 4a is lower than the nicotine filtration rate of the filter section 2 before the opening 4a. In the present invention, the ratio of the nicotine filtration rate in the filter section 2 after the opening 4a to the nicotine filtration rate in the filter section 2 before the opening 4a is preferably 70 to 90%. With this range, the ventilation air can selectively flow through the sheath portion 2b. These nicotine filtration rates can be measured separately for the filter that has been smoked according to the Cholesta method at the opening 4a and before and after the opening 4a.

In the present invention, the filters 1, 1
It is preferable that the filtration rate of tars A and 1B is 80% or more. If it is less than 80%, it may be difficult to constitute a low tar tobacco having a tar value of 3 mg or less. The tar filtration rate can be changed by adjusting the material of the core portion 2a and the sheath portion 2b, the weight ratio, the configuration such as the cross-sectional area, or the ventilation rate.

The operation of the filters 1, 1A, 1B will be described below. In the filter section 2, the flow rate of the core section 2a is lower than the flow rate of the sheath section 2b as described above. For this reason, when a smoking operation is performed, the distribution of smoke differs between the core portion 2a and the sheath portion 2b, and the core portion 2a
The smoke arriving at the smoker's mouth from each of the and the sheath portion 2b has different characteristics such as the speed of arrival and the concentration of the smoke particle component.

For this reason, the smoker can enjoy the taste of smoke by tasting the smoke having an appropriate concentration flowing out of the core portion 2a after the smoke flowing out of the sheath portion 2b. In addition, the smoke passing through the sheath portion 2b is reduced in tar by dilution of ventilation air, and the smoke is transmitted through the core portion 2a with a high filtration efficiency, thereby increasing the filtration efficiency of the entire filter 1, 1A, 1B. it can.

As a result, the filters 1, 1A, 1B
Can be used to produce low tar tobacco with a tar value of 3 mg or less, preferably 1 mg or less, and tobacco with little lack of taste. The tar value of tobacco using the filter of the present invention is a value measured according to the Coresta method, and can be adjusted by the configuration of the tobacco body, the configuration of the filter, and the like.

FIG. 6 is a schematic structural view of an apparatus used in a first example of a preferred method of manufacturing a filter according to the present invention. Hereinafter, description will be given according to the manufacturing operation. First, when a fiber material that needs to be opened like a tow is used as the material for the core, the toe-like core material 10A drawn from the bale is
The fiber is supplied to the fiber opening device 11A and uniformly opened. And
After passing through the terry berry roll 12A, preferably, a plasticizer such as triacetin is uniformly attached thereto to form a sheet-shaped core material 10B. Then, the sheet core material 10B is supplied to the corrugating thermoforming device 14. On the other hand, when a material (web) such as a nonwoven fabric or a film that does not need to be spread is used as the material of the core portion, the sheet-shaped core portion material 10B can be directly supplied to the corrugating thermoforming device 14 via the guide 13. it can.

The corrugating thermoforming device 14 includes two upper and lower nip rolls each having a large number of grooves. And
The grooves of the upper and lower nip rolls mesh with each other, and
Any device can be used as long as it has the function of adjusting the clearance with the following thickness, the ability to pressurize at a predetermined pressure, and the ability to thermoform at a predetermined temperature. it can.

The filter characteristics change depending on the clearance between the nip rolls of the corrugating thermoforming device 14, the pressure, the temperature, and the speed. Therefore, these conditions are determined according to the characteristics of the target filter. Specifically, for example, the clearance between the nip rolls of the corrugating thermoforming device 14 is 0.5 mm or less, the pressure between the rolls is in the range of 0.5 to 6 kg / cm ² G, and the temperature is 60 to 180.
The temperature is preferably in the range of ° C. The clearance is 0.
If it exceeds 5 mm, and if the temperature is lower than 60 ° C., corrugating is difficult. On the other hand, when the temperature exceeds 180 ° C., on the other hand, sheet formation proceeds too much, making it difficult to obtain a filter material having sufficient airflow resistance, and lowering the production stability.

Next, the corrugated sheet 6 that has been corrugated in the corrugating thermoforming device 14 is pulled out from the extra roll 15. Further, after passing through the first ring guide 16 and the second ring guide 17, it is passed through a thermoforming converging device 18 to converge, and the outer peripheral surface thereof is heat-sealed to form a cylindrical convergent material. And stabilize the shape. Then, the water is supplied into the inner pipe of the double pipe 19. In the case where a fiber tow or the like is used as it is without corrugating, and is used as it is, the core portion is formed without passing through the corrugating thermoforming device 14 and passing through the fiber opening device 11A and the delivery roll 12A. To supply.

The thermoforming converging device 18 has a converging path for passing the corrugated sheet 6 while converging it while heating. The area of the cross section of the converging path gradually decreases from the entrance side to the exit side. The shape of the cross section is circular, elliptical,
It can be changed to a square, pentagon, star, etc. as appropriate.

The temperature and speed of the thermoforming converging device 18 are preferably determined in accordance with the characteristics of the target filter. Specifically, for example, the temperature of the thermoforming convergence device 18 is
Although it depends on the material of the corrugated sheet 6, 60 to 30
The temperature is preferably in the range of 0 ° C. If the temperature is lower than 60 ° C, thermoforming becomes difficult. If the temperature exceeds 300 ° C,
The melting of the corrugated sheet 6 progresses too much, making it difficult to form a converged product while maintaining a uniform corrugated shape. The cross-sectional area of the outlet of the thermoforming converging device 18 is usually the cross-sectional area of the core 2a. Also, depending on the properties and sheet width of the corrugated sheet 6, the cross-sectional area of the core portion 2a and
Preferably, the cross-sectional area of the outlet is adjusted. That is, if the cross-sectional area of the outlet is too small, the resistance in the converging path increases, and the speed at which the corrugated sheet 6 is supplied to the converged sheet 6 in a later step is reduced, which may lower the production efficiency. Further, if the cross-sectional area of the outlet is too large, the voids in the convergent object increase, stiffness is lost, and a convergent object having a uniform shape may not be obtained.

On the other hand, the sheath portion material 21 such as a long fiber crimped tow is supplied to the fiber opening device 11B and uniformly opened. Further, it is passed through the delivery roll 12B, and preferably a plasticizer such as triacetin is uniformly attached. Next, the first ring guide 16 and the second ring guide 17
, The cross-sectional shape of the opened fiber tow sheet is expanded in an arc shape, and while being formed into a cylindrical shape, the fiber tow sheet is supplied between the outer tube and the inner tube of the double tube 19 and converges to a tubular body. ,
The filter unit is formed integrally with a cylindrical convergent material serving as a core unit supplied into the inner tube. This is supplied to the filter plug machine 20 together with the web 3.

In the filter plug machine 20,
At least one edge of the web 3 is coated with an adhesive,
While being wound around the outer periphery of the filter portion, the edge is adhered to be integrated with the filter portion. Then, it is cut into a predetermined length by a cutter to obtain a filter chip. Thus, the filter 1A having the cross-sectional shape shown in FIG. 4A can be obtained. Thereafter, according to a conventional method, for example, the tobacco main body and the filter chip are abutted, and the tip paper is wound and bonded integrally on the filter chip and around the joint of the tobacco main body with the filter chip. To complete.

FIG. 7 is a schematic diagram showing an example of an apparatus used in a second example of the method for manufacturing a filter according to the present invention. As shown in FIG. This is to manufacture a filter 1B having a configuration in which a paper roll 3 'is provided around the filter 1B. This device differs from the device shown in FIG. 6 in that a core portion converging guide 22 and a core portion winding tube portion 23 are provided between the extra roll 15 and the first ring guide 16. .

That is, in the core portion convergence guide 22, a converged product of the corrugated sheet 6 supplied from the extra roll 15 is formed and supplied to the core portion winding tube portion 23 together with the web 3 '. Then, in the core winding tube portion 23, a winding paper 3 'coated with an adhesive on one end is wound around the converged material of the corrugated sheet 6, and the end is adhered with the adhesive. The converged object and the web 3 'are integrated. Thus, the cross-sectional area of the core portion is set to a predetermined cross-sectional area, and the shape in the length direction is stabilized. The integrated product of the converged material and the web 3 ′ is separated into a first ring guide 16 and a second ring guide 17.
The following operation of supplying to the thermoforming converging device 18 via the above and integrating with the tubular body to be the sheath portion is the same as in the first example shown in FIG.

[0049]

EXAMPLES A filter was manufactured in the following manner, a tobacco was constructed using the filter, and its characteristics were evaluated. In addition, the measurement item in an Example is each measured by the method shown below. <Ventilation Resistance> The ventilation resistance is based on the Coresta method, and the ventilation resistance of the tobacco, and the ventilation resistance of each of the core portion and the sheath portion is measured using an OTIC type suction resistance measuring device manufactured by Kato Kogyo Co., Ltd. according to the method described above. did. The measurement result is
In Tables 1 and 2, the results are shown in the items of "core portion airflow resistance", "sheath portion airflow resistance", and "tobacco airflow resistance". <Converted airflow resistance> It was determined from the value of the airflow resistance measured by the method described above. In Table 1, "Core / sheath equivalent ventilation resistance ratio"
Items. <Flow rate in core section and flow rate in sheath section> As a flow rate measuring device, a laminar flow meter 23 manufactured by Dyna Science Co., Ltd. is used.
Were used to construct the apparatus shown in FIGS. 8 and 9, and measurement was performed by the above-described method. Inner diameter D of flow path dividing member of sample holder
Were sequentially changed according to the diameter of each core part. The measurement results are shown in Table 3 in the items of “core portion flow rate” and “sheath portion flow rate”.

<Measurement of Tar and Nicotine in Smoke of Tobacco> The amount of smoking of tar and nicotine in smoke due to smoking was measured based on the Coresta method using a rotary smoker RM20 / CS manufactured by Borgwald. The measurement results are shown in Table 2 under the item “tar / nicotine smoking amount”. <Each nicotine smoking amount in core and sheath> Fig. 1
A smoking amount measuring apparatus as shown in FIG. This device is different from the flow measuring device shown in FIG.
3a and 43b are replaced by Cambridge filters 44a and 44b
It has been changed to. Using this device, a smoking operation is performed, and smoke particle components flowing out of the core and the sheath due to smoking of one cigarette are removed from the Cambridge filters 44a and 44.
b and captured by gas chromatography and quantified by gas chromatography. In Table 2, the ratio of the measurement result of the core portion to the total of the measurement results of the core portion and the sheath portion is shown in the item of "the ratio of the amount of nicotine smoked from the core portion in the filter" in Table 2.

Example 1 A filter was manufactured using the apparatus shown in FIG. 6 to form a filter having a sectional shape shown in FIG. 4A. The core was formed from a corrugated sheet made of cellulose acetate tow. Also,
As the sheath portion, a tubular tobacco filter plug (circumference 24.6 mm) made of cellulose acetate tow was manufactured and used. Filter tip length is 25
mm. Table 1 shows the configuration of the core and the sheath. In Table 1, "core tow", "sea toe"
The characteristics of the cellulose acetate tow constituting the core portion and the sheath portion are described in the item of fineness (dpf value) /
It is shown by the value of total denier.

A chip paper was wound around the filter chip and glued, and connected to a tobacco main body to complete a filter and tobacco was manufactured. At this time, no gluing was performed on the opening of the chip paper. The tobacco body used had the same configuration as that of the Japanese tobacco industry Co., Ltd. except for the filter part of "Alpha". Roll paper is porous paper, air permeability 30000
CU was used. The chip paper used a laser with four rows of holes and an air permeability of 1200 CU. The apertures were provided in a line along the outer circumference of the chip paper at a position 12.5 mm from the filter suction end face. Table 2 shows the tobacco evaluation results.
Table 3 shows the flow rate of each part of the filter.

(Example 2) An apparatus shown in FIG. 7 was used, except that a wrapping paper was wrapped around a core portion and that cellulose acetate tow was used as it was without corrugating the core portion. In the same manner as in Example 1, a filter was produced, and tobacco was produced. As the paper roll wound around the core portion, porous paper and air permeability of 30,000 CU were used. Table 1 shows the configuration of the core and the sheath. Table 2 shows the evaluation results of tobacco, and Table 3 shows the flow rates of the respective parts of the filter.

(Example 3) A filter was produced in the same manner as in Example 2 except that the core portion was formed from a corrugated sheet made of cellulose acetate tow, and tobacco was produced. Table 1 shows the configuration of the core and the sheath. Table 2 shows the evaluation results of tobacco, and Table 3 shows the flow rates of the respective parts of the filter.

Comparative Example 1 Example 1 was repeated except that the filter portion had a uniform structure made of cellulose acetate tow.
A filter and a tobacco having the same configuration as those described above were produced. Table 1 shows the configuration of the filter unit, and Table 2 shows the evaluation results of the tobacco. In addition, when the inner diameter D of the flow path dividing member of the sample holder is changed in steps of 1 mm between 2 and 6 mm, the central portion (described in the item of “core portion flow rate”) and the outer peripheral portion (of the “sheath portion flow rate”) are changed. (Described in the item) were measured and shown in Table 3.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

From Table 3, it can be seen that in the filters of Examples 1 to 3 according to the present invention, the flow velocity in the core portion is small. And, "the ratio of the amount of nicotine smoked from the core portion in the filter" shown in Table 2 is large, and it can be seen that the smoke flowing out from the core portion can provide a sufficient taste satisfaction. Therefore, the tobacco of Examples 1 to 3 has a tar value of 3
Even with low tar tobacco of not more than mg, it is possible to obtain a satisfactory feeling of smoking, such as a strong flavor and a feeling of smoke, without losing the taste.

[0060]

As described above, in the filter of the present invention, since the flow velocity of the sheath is increased, the smoke permeating the sheath is diluted by ventilation air and reduced in tar to reduce smoke. Spills into the mouth.
On the other hand, smoke passing through the core is not diluted by ventilation air, but slowly passes through the core, is filtered with high filtration efficiency, and becomes smoke having an appropriate concentration that does not impair the taste. It escapes after smoke permeating the sheath. As a result, the smoker can enjoy a sense of taste by enjoying the smoke flowing out of the core portion after the smoke flowing out of the sheath portion. In addition, smoke passing through the sheath portion is reduced in tar by dilution of ventilation air, and high filtration efficiency is obtained in the core portion. Therefore, the filtration efficiency of the entire filter can be increased to reduce tar. For this reason, the filter of the present invention can constitute a low tar tobacco having a tar value of 3 mg or less, preferably 1 mg or less, and can obtain a satisfaction by smoking without impairing the taste.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a tobacco filter of the present invention, which is cut in a direction perpendicular to an axial direction.

FIG. 2 is a side cross-sectional view of an example of the tobacco filter of the present invention cut in parallel to the axis direction.

FIG. 3 is an explanatory view showing a configuration of a corrugated sheet.

FIG. 4A is a cross-sectional view of an example of a filter having a cylindrical core portion cut in a direction orthogonal to an axial center direction. FIG. 4B is a cross-sectional view illustrating an example of a filter in which a breathable paper is wound around a core portion, which is cut in a direction perpendicular to an axial direction.

FIGS. 5A to 5F are cross-sectional views showing various examples of a cross-sectional shape of a core portion of a filter, which are cut in a direction orthogonal to an axial direction.

FIG. 6 is a schematic configuration diagram of an apparatus used in a first example of the filter manufacturing method of the present invention.

FIG. 7 is a schematic configuration diagram of an apparatus used in a second example of the filter manufacturing method of the present invention.

8 is an enlarged cross-sectional view of a sample holder used in the example of the flow measurement device shown in FIG.

FIG. 9 is a schematic configuration diagram of an example of a flow measurement device.

FIG. 10 is a schematic configuration diagram showing a smoking amount measuring device used in Examples.

[Explanation of symbols]

1, 1A, 1B: filter, 2a: core, 2b: sheath, 2: filter, 3, 3 '... roll paper, 4 ... chip paper, 4a ... aperture (hole), 5a: cigarette body (tobacco) 5) Tobacco, 6 ... Corrugated sheet.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiichi Takase 3 Kaigan-dori, Toyama City, Toyama Prefecture Inside Mitsubishi Rayon Co., Ltd.

Claims (12)

[Claims] 1. A tobacco filter having a high filtration rate for low tar tobacco having a tar value per tobacco of 3 mg or less, comprising a core portion provided at a center and a sheath portion provided around the core portion. A flow rate of air passing through the core section is 30 cm / sec when the flow rate of air passing through the core section is lower than the flow rate of the sheath section at a rate of 17.5 ml / sec.
c or less, and the filtration rate of tar is 80% or more, and the ratio of the cross-sectional area of the core part to the cross-sectional area of the filter part is 20 to 70%. High tobacco filter. 2. The tobacco filter according to claim 1, wherein the ratio of the reduced airflow resistance of the core portion to the reduced airflow resistance of the sheath portion is 1.5 to 4. 3. The tobacco filter having a high filtration rate according to claim 1, wherein the nicotine filtration rate is 70 to 90%. 4. The tobacco filter with a high filtration rate according to claim 1, wherein a weight ratio of the core portion to the filter portion is 45 to 70%. 5. The airflow resistance of the filter section is 100 to 100.
Claim, characterized in that 170mmH a ₂ O 1 to 4
The tobacco filter having a high filtration rate according to any one of the above. 6. The airflow resistance of the core portion is 500 to 100.
High cigarette filter of filtration rate of any one of claims 1 to 5, characterized in that 0mmH a ₂ O. 7. A filter ventilation rate of 60 to
The tobacco filter having a high filtration rate according to any one of claims 1 to 6, wherein the tobacco filter has a filtration rate of 80%. 8. A paper roll wound around the filter section, and a tip paper wound on the paper roll, wherein the air permeability of the paper roll is 10,000 to 30,000 CU, and the air permeability of the chip paper is 1200. ~ 3600
The tobacco filter having a high filtration rate according to any one of claims 1 to 7, which is a CU. 9. A paper roll wound around the filter section, and a tip paper wound on the roll paper, wherein the tip paper is provided along an outer periphery thereof.
2. An opening for introducing ventilation air, wherein a ratio of a nicotine filtration rate after the opening to a nicotine filtration rate before the opening is 70 to 90%. The tobacco filter having a high filtration rate according to any one of claims 1 to 8. 10. The tobacco filter with a high filtration rate according to claim 1, wherein the sheath portion is made of a fiber tow. 11. The tobacco filter according to claim 1, wherein the core portion is formed by converging a corrugated sheet. 12. The tobacco filter having a high filtration rate according to claim 1, wherein one or both of the core and the sheath are made of cellulose acetate fiber.