CN106572698B

CN106572698B - Cigarette with filter tip

Info

Publication number: CN106572698B
Application number: CN201480081029.5A
Authority: CN
Inventors: 二宫悠; 板桥谦一
Original assignee: Japan Tobacco Inc
Current assignee: Japan Tobacco Inc
Priority date: 2014-08-07
Filing date: 2014-08-07
Publication date: 2020-09-04
Anticipated expiration: 2034-08-07
Also published as: EP3178333B1; RU2663381C1; KR20170041797A; JPWO2016021021A1; TWI576054B; CN106572698A; KR102121894B1; EP3178333A1; TW201605360A; EP3178333A4; JP6218948B2; WO2016021021A1; KR20190104635A

Abstract

The invention provides a cigarette with a filter, which makes tar pollution on the end face of a suction nozzle difficult to detect and prevents the occurrence of insufficient hardness of a filter. The filter cigarette of the present invention comprises a tobacco rod containing tobacco shreds and a filter connected to an end of the tobacco rod via a tipping paper, and is characterized in that the filter comprises: a nozzle tip section disposed at the nozzle tip, the nozzle tip section including a cylindrically shaped fiber bundle and a first smoke passage extending through the fiber bundle in the longitudinal direction; the front section, which is continuously provided at the tip of the nozzle end section, includes a fiber bundle formed in a cylindrical shape and a second smoke flow path that penetrates the fiber bundle in the longitudinal direction, and the cross-sectional flow area of the first smoke flow path is larger than the cross-sectional flow area of the second smoke flow path.

Description

Cigarette with filter tip

Technical Field

The present invention relates to a cigarette with filter tip.

Background

In a filter cigarette, the smoke content of cigarettes such as tar, nicotine, and CO (carbon monoxide) is controlled (adjusted) by adjusting the balance between air dilution by introducing ventilation air through ventilation holes formed in the outer periphery of the filter and filtration by a filter material.

However, since CO is a gas phase component, it cannot be filtered through a filter material, and the concentration in smoke is reduced by dilution with air. On the other hand, tar is reduced by both the filtration of the filter material and the dilution of air. Therefore, as a method of designing a filter cigarette, a low-filtration high-dilution design, that is, a design in which the filtration ratio of the filter material is reduced and the dilution ratio is increased, is sometimes performed. According to this low-filtration high-dilution design, the ratio of CO to tar can be reduced, the smoking taste can be enhanced, and an effect of improving flavor can be expected.

To achieve a low filtration high dilution design, various methods are employed. For example, a method is known in which the diameter of the fibers of the filter material is increased to reduce the density, thereby reducing the ventilation resistance of mainstream smoke, or the diameter of the ventilation holes into which ventilation air flows is increased, thereby increasing the dilution ratio. However, since the circumferential length of the cigarette, the length of the filter, the material used for the filter material, and the like are limited, the reduction of the ventilation resistance of the filter material by the above-described method is also limited.

Therefore, a design method has been proposed in which a segment having no filtering function for mainstream smoke is disposed in a partial section of a filter, for example, a center hole filter provided with a through hole is disposed in the center of the axis, or a design method in which a recess, a cavity, or the like is formed in a partial section of a filter to realize low-filtration and high-dilution.

Documents of the prior art

Patent document

Patent document 1: japanese unexamined patent publication No. 5-23158

Disclosure of Invention

Problems to be solved by the invention

However, merely providing a non-filtering section having no filtering function for mainstream smoke in a partial section of the filter can achieve low-filtration and high-dilution of mainstream smoke, but may cause the following problems. For example, when a center hole filter is used, tar is likely to be locally attached to the periphery of the center hole on the nozzle end surface, and tar contamination on the nozzle end surface after smoking tends to become conspicuous. On the other hand, when a recess is formed on the mouth end side of the filter or a cavity is formed in the middle portion, the hardness of the filter tends to be insufficient.

The present invention has been made in view of the above problems, and an object thereof is to provide a technique for preventing insufficient hardness of a filter while making it difficult to detect tar contamination on a mouth end surface of a cigarette with a filter.

Means for solving the problems

In order to solve the above problems, the present invention is configured such that a through passage through which mainstream smoke flows is formed in each of a mouth end section disposed at a mouth end of a filter and a front section continuously provided at a tip end of the mouth end section, and a flow passage cross-sectional area of the through passage in the mouth end section is larger than a flow passage cross-sectional area of the through passage in the front section.

More specifically, the filter cigarette of the present invention comprises a tobacco rod containing tobacco shreds and a filter connected to an end of the tobacco rod via a tipping paper sheet, and is characterized in that the filter comprises: the section of the suction nozzle end, which is configured at the suction nozzle end, is provided with a fiber bundle, and the fiber bundle forms a through passage for flowing of the main stream smoke along the axial direction; a front section continuously provided at the front end of the nozzle end section, and a fiber bundle provided with a through passage for mainstream smoke to flow along the axial direction, wherein the cross-sectional area of the through passage of the nozzle end section is larger than that of the front section

According to the present invention, in the cross-sectional area of the through passage of the nozzle end section, the flow velocity (flow rate) of the mainstream smoke flowing through the region on the outer peripheral side that does not overlap the through passage of the front section in the axial direction is relatively slower (less) than the region on the center side that overlaps the through passage of the front section in the axial direction. Thus, when the mainstream smoke is drawn into the oral cavity from the rear end of the through passage in the mouthpiece end section, the frequency (chance) of contact between the mouthpiece end face of the filter and the mainstream smoke can be reduced. As a result, tar is less likely to adhere locally to the periphery (edge portion) of the through passage of the nozzle end face. Therefore, tar contamination on the mouth end surface of the filter can be suppressed, and it can be made less noticeable. Further, according to the present invention, since it is not necessary to provide a section such as a cavity or a recess in the filter, the occurrence of insufficient hardness in the filter can be prevented.

In the present invention, the length of the nozzle end section may be shorter than the length of the front section. With this configuration, the lack of hardness in the filter can be more reliably suppressed from becoming conspicuous.

In the present invention, the nozzle end section and the front section may have through passages coaxially arranged. With this configuration, tar contamination on the mouthpiece end face of the filter can be made less noticeable.

In the present invention, a cut tobacco overflow suppressing means for suppressing the cut tobacco from entering the filter may be provided at the tip end portion of the filter. With this configuration, the cut tobacco of the tobacco rod can be appropriately prevented from entering the filter.

In the present invention, a filter material including a fiber bundle for filtering mainstream smoke may be disposed at a distal end portion of the filter, and the filter material may also serve as the tobacco shred overflow suppressing means. With this configuration, the material cost of the filter can be reduced, and the filter manufacturing process can be prevented from becoming complicated.

In the present invention, the tipping paper sheet may be provided with ventilation holes for introducing outside air into the filter to dilute mainstream smoke, and the ventilation holes may be disposed upstream of the mouth end section of the filter. This configuration has an advantage that the mainstream smoke can be easily moved toward the center side in the front section.

In addition, the technical means for solving the problems of the present invention may be adopted in combination as much as possible.

Effects of the invention

According to the present invention, there is provided a technique for preventing insufficient hardness of a filter while making it difficult to detect tar contamination on a mouth end surface of a cigarette with a filter.

Drawings

Fig. 1 is a longitudinal sectional view of a cigarette according to embodiment 1.

Fig. 2 is a perspective view of the cigarette according to embodiment 1.

Fig. 3 is a diagram showing a device for producing a center hole filter according to embodiment 1.

Fig. 4 is a longitudinal sectional view of a filter of a comparative example.

FIG. 5 is a schematic view showing tar contamination on the mouth end surface of a filter of a comparative example.

Fig. 6 is a diagram illustrating another modification of the position of the ventilation holes in the filter according to embodiment 1.

Fig. 7 is a longitudinal sectional view of a cigarette according to modification 1.

Fig. 8 is a longitudinal cross-sectional view of a cigarette according to modification 2.

Fig. 9 is a longitudinal cross-sectional view of a cigarette according to modification 3.

Detailed Description

Hereinafter, embodiments of the filter cigarette according to the present invention will be described in detail with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the constituent elements described in the present embodiment are not intended to limit the technical scope of the present invention to the above conditions unless otherwise specified.

< embodiment 1 >

Fig. 1 is a longitudinal sectional view of a cigarette according to embodiment 1. Fig. 2 is a perspective view of the cigarette according to embodiment 1. The cigarette 1 is a filter cigarette including a tobacco rod 2 and a filter 4 connected to one end of the tobacco rod 2 via a tipping paper 3.

The tobacco rod 2 is formed by winding the tobacco thread 21 around the roll paper 22 into a cylindrical shape (rod shape), and is also referred to as a "single roll". The filter 4 is a member for filtering smoke components contained in mainstream smoke when mainstream smoke generated during smoking of the cigarette 1 passes through, and is formed in a cylindrical shape having substantially the same diameter as the tobacco rod 2.

The filter 4 is wrapped with a tipping paper 3, and is connected to the rear end side of the tobacco rod 2 via the tipping paper 3. The tipping paper sheet 3 is formed by integrally winding the end of the tobacco rod 2 and the filter 4, and connects (joins) these. Hereinafter, the end portion of the tobacco rod 2 that is connected to the filter 4 in the longitudinal direction (axial direction) is referred to as "rear end", and the end portion opposite to the rear end is referred to as "front end" (tip end). In the longitudinal direction (axial direction) of the filter 4, the end portion connected to the tobacco rod 2 is referred to as "tip end", and the end portion opposite to the tip end is referred to as "mouth end". The cross section of the cigarette 1 (tobacco rod 2, filter 4) along the longitudinal direction (axial direction) is defined as a "vertical cross section", and the cross section in the direction perpendicular to the vertical cross section is defined as a "cross section". Note that reference symbol CL shown in fig. 1 denotes the central axis of the cigarette 1 (tobacco rod 2, filter 4).

Inside the filter 4, a filter section S1, a front section S2, and a mouthpiece section S3 are arranged in this order from the front end side. The filter segment S1 is provided with a filter material 41 formed by winding a fiber bundle of cellulose acetate formed into a cylindrical shape with a winding paper. However, the filter material 41 of the present embodiment is not limited to the cellulose acetate fiber bundle, and various materials can be used.

Central hole filters 42 and 43, which are formed in a cylindrical shape and in which a fiber bundle of cellulose acetate having a through passage formed in the axial direction is wound by a wound paper, are disposed in the front section S2 and the nozzle end section S3, respectively. Hereinafter, the through passage formed in the central hole filter 42 in the front segment S2 will be referred to as "first central hole 42 a". In addition, the through passage formed in the central hole filter 43 of the nozzle end section S3 is referred to as a "second central hole 43 a".

The first central hole 42a passes through the center of the central hole filter 42 and penetrates in the axial direction. On the other hand, the second central hole 43a passes through the center of the central hole filter 43 and penetrates in the axial direction. The first center hole 42a and the second center hole 43a are smoke flow paths (passages) for allowing the main flow of smoke to flow (pass through). In the present embodiment, the first center hole 42a and the second center hole 43a are coaxially arranged, and the cross-sectional area of the second center hole 43a is larger than the cross-sectional area of the first center hole 42 a. In other words, the sectional area of the through passage in the nozzle-end section S3 is set larger than the sectional area of the through passage in the front section S2. Further, the length of the mouth end section S3 (central hole filter 43) in the filter 4 is shorter than the length of the front section S2 (central hole filter 42). In the present embodiment, the cross-sectional shapes of the first center hole 42a and the second center hole 43a are circular, but the present invention is not limited thereto.

The tipping paper 3 around which the filter 4 is wrapped is formed with a ventilation hole 31 for introducing ventilation air (outside air) into the filter 4 to dilute mainstream smoke. As shown in fig. 1, the ventilation holes 31 are arranged in the filter 4 at positions corresponding to the filter sections S1. During smoking, external air flows into the filter 4 through the ventilation holes 31, and the air introduced from the ventilation holes 31 is mixed with the mainstream smoke flowing into the filter 4 from the tobacco rod 2 side, thereby diluting the mainstream smoke.

Next, an example of a method for producing the center hole filters 42 and 43 will be described. The central pore filters 42, 43 can be manufactured by various known methods. Fig. 3 is a diagram showing a device 100 for producing a center hole filter. The manufacturing apparatus 100 includes a storage container 110 for storing filter fibers (e.g., cellulose acetate) 150, a plasticizer adding unit 120, a molding apparatus 130, a wrapping apparatus 140, and the like. The filter fibers 150 stored in the storage container 110 are drawn out along a predetermined unwinding path. Also, during this unwinding, the filter fibers 150 are subjected to a fiber opening process, and thus are expanded into a sheet shape. Then, the sheet-like filter fibers 150 are supplied to the forming device 130 at the subsequent stage by the plasticizer adding unit 120 after receiving the addition of the plasticizer such as triacetin.

The molding device 130 is a molding device for molding the sheet-like filter fibers 150 into a hollow rod-like filter continuous body, and includes a mandrel (not shown) as a tubular molding path, and molds the sheet-like filter fibers 150 into a hollow rod-like filter continuous body by passing them through the mandrel in a contracted state. The sheet-like filter fibers 150 supplied to the forming device 130 are formed into a rod shape around the mandrel, are sequentially drawn out, and are drawn out from the mandrel to form a central hole. The filter continuous body with the central hole thus formed is supplied to the wrapping device 140 of the rear stage. The filter continuous body supplied to the wrapping device 140 is wound with a wrapping paper to form a filter rod, and the filter rod is cut into a predetermined length to produce the center hole filters 42 and 43.

Next, the operation and effect of the cigarette 1 of the present embodiment will be described. When the mainstream smoke generated in the tobacco rod 2 flows into the filter 4 during smoking of the cigarette 1, components in the smoke such as tar and nicotine are filtered when the mainstream smoke passes through the filter material 41 in the filter section S1. In addition, since CO contained in the mainstream smoke is a gas phase component, it is not filtered by the filter material 41. Since the ventilation holes 31 penetrating the tipping paper sheet are arranged in the filter section S1 of the filter 4, the air introduced through the ventilation holes 31 is mixed with the mainstream smoke passing through the filter section S1. This dilutes smoke components in the mainstream smoke, and reduces tar, nicotine, CO, and the like contained in the mainstream smoke.

However, the filter 4 of the present embodiment is designed to have a low-filtration high-dilution, that is, the low-filtration high-dilution is achieved by balancing the dilution of the air introduced through the ventilation holes 31 and the filtration of the filter material 41. More specifically, by providing sections having no function of filtering mainstream smoke, i.e., the front section S2 and the mouthpiece-end section S3, in a partial section of the filter 4, low-filtration high dilution is achieved.

Here, the front stage section S2 and the nozzle end section S3 are provided with center hole filters 42 and 43 having a first center hole 42a and a second center hole 43a, respectively, which are hollow. The central hole filter 42 has a cross section in which regions other than the hollow first central hole 42a are occupied by the compression-molded fiber bundle. Therefore, in the cross section of the center hole filter 42, the air flow resistance of the region occupied by the fiber bundle can be said to be much larger than the air flow resistance of the first center hole 42 a. Also, the central hole filter 43 has a cross section in which the region other than the hollow second central hole 43a is occupied by the compression-molded fiber bundle. Therefore, in the cross section of the center hole filter 43, the air flow resistance of the area occupied by the fiber bundle can be said to be much larger than the air flow resistance of the first center hole 43 a. Therefore, the mainstream smoke passing through the filtering section S1 flows through the first central hole 42a and the second central hole 43a having extremely low ventilation resistance in this order, and is finally drawn from the mouthpiece end into the oral cavity. As described above, the filter 4 of the present embodiment has a filtering function of filtering smoke components of mainstream smoke only in the filtering section S1, and the subsequent front section S2 and mouthpiece section S3 do not have a filtering function of filtering smoke components. Therefore, the balance of dilution and filtration of the main stream smoke reaches low filtration and high dilution, and the proportion of CO relative to tar can be reduced. As a result, the smoking taste of the cigarette 1 is enhanced, and the flavor thereof can be improved.

Furthermore, in the cigarette 1 of the present embodiment, in order to suppress tar from locally adhering to the mouthpiece end face of the filter 4 at the time of smoking, the relationship between the cross-sectional areas of the two through passages is defined such that the cross-sectional area of the second central hole 43a in the mouthpiece end section S3 is larger than the cross-sectional area of the first central hole 42a in the front section S2. The filter 4 of the present embodiment will be described below with reference to comparative examples shown in fig. 4 and 5.

Fig. 4 is a longitudinal sectional view of a filter 40 of a comparative example. The filter 40 is provided with a filter material 410 and a center hole filter 430 continuously from the distal end side. The filter material 410 and the central pore filter 430 of the filter 40 are substantially equal to the filter material 41 and the central pore filter 43 of the filter 4 of the present embodiment. That is, the filter 40 of the comparative example has substantially the same configuration as the filter 4 shown in fig. 1 except that the front segment S2 (central hole filter 42) is removed.

When the cigarette having the filter 40 of the comparative example is smoked, the mainstream smoke flowing from the tobacco rod side to the filter 40 flows through the filter material 410 and the central hole 430a of the central hole filter 430 in this order and is drawn into the oral cavity. Fig. 5 is a diagram schematically showing local tar contamination on the mouth end surface of the filter 40 of the comparative example. When the cigarette of the comparative example was smoked, tar was likely to be locally attached to the periphery (edge portion) of the central hole 430a on the nozzle end surface, and tar contamination on the nozzle end surface was likely to become conspicuous.

On the other hand, in the filter 4 of the present embodiment, the cross-sectional area of the second central hole 43a of the mouth end section S3 is set to be larger than the cross-sectional area of the first central hole 42a of the front section S2 provided continuously upstream of the mouth end section S3, so that local tar contamination around (at the edge of) the second central hole 43a on the mouth end surface can be made inconspicuous.

That is, as shown in fig. 1, in the filter 4 of the present embodiment, the cross-sectional area of the flow path of the mainstream smoke increases at the boundary position between the front section S2 located on the back side of the mouth end face and the mouth end section S3 (first central hole 42a → second central hole 43 a). When the mainstream smoke flows into the second central hole 43a from the first central hole 42a at the boundary position between the front stage section S2 and the nozzle end section S3, the mainstream smoke flows into the second central hole 43a while expanding in the cross-sectional direction. Therefore, local tar deposition can occur around (at the edge of) the first central hole 42a on the rear end surface of the central hole filter 42. However, as shown in fig. 1, the rear end face of the center hole filter 42 is disposed at a position distant from the nozzle end face inward by the length of the nozzle end section S3. Therefore, there is an advantage that even if local adhesion of tar occurs around the first central hole 42a on the rear end surface of the central hole filter 42, the tar contamination is difficult to be recognized by the smoker.

Next, the difference in the flow velocity (flow rate) of the mainstream smoke flowing through the center side and the outer peripheral side of the second center hole 43a will be described. Since the cross-sectional area of the second center hole 43a is larger than that of the first center hole 42a, the center side of the second center hole 43a overlaps with the first center hole 42a in the axial direction, but the outer peripheral side does not overlap with the first center hole 42a in the axial direction. As a result, the flow velocity (flow rate) of the mainstream smoke in the outer peripheral region is relatively slower (smaller) than that in the center side of the second center hole 43 a. By reducing the flow velocity (flow rate) of the mainstream smoke flowing on the outer peripheral side of the second center hole 43a in this manner, the frequency of contact between the mainstream smoke sucked into the oral cavity from the rear end of the second center hole 43a and the nozzle end face can be reduced. Therefore, the local tar deposition around (at the edge of) the second center hole 43a on the nozzle end surface can be made less likely to occur. As a result, tar contamination on the mouth end surface of the filter 4 can be suppressed and made inconspicuous.

Furthermore, according to the present embodiment, low filtration and high dilution of the filter 4 can be achieved without providing a section such as a cavity or a recess in which the entire cross section of the filter 4 is hollow (hollow). This prevents the occurrence of insufficient hardness in the entire longitudinal direction of the filter 4. Therefore, the occurrence of a problem that the filter 4 is inadvertently deformed before or during smoking can be suppressed. As described above, according to the cigarette 1 of the present embodiment, tar contamination on the mouth end surface of the filter 4 is made inconspicuous, and insufficient hardness of the filter 4 can be prevented favorably.

Further, the filter 4 of the present embodiment is set such that the length of the mouth end section S3 is shorter than the length of the front section S2. Here, since the thickness (wall thickness) of the center hole filter 43 is smaller than the thickness (wall thickness) of the center hole filter 42, the hardness of the filter 4 can be more reliably prevented from becoming less conspicuous by making the length of the center hole filter 43 shorter than the length of the front segment S2.

In the present embodiment, the first central hole 42a and the second central hole 43a in the filter 4 are arranged coaxially. With this configuration, the frequency of contact between the mainstream smoke flowing out of the second central hole 43a on the suction nozzle end surface and the suction nozzle end surface can be reduced more uniformly over the entire circumference of the second central hole 43 a. As a result, tar contamination on the mouth end surface of the filter 4 can be made less noticeable.

Furthermore, in the present embodiment, since the filter material 41 is provided in the filter section S1 located at the tip end portion of the filter 4, the filter material 41 can be made to function as cut tobacco overflow suppressing means for preventing the cut tobacco 21 of the tobacco rod 2 from entering (overflowing) into the filter 4. That is, the filter material 41 of the filter section S1 also serves as the cut tobacco overflow suppressing means. The tobacco shred overflow suppressing means is not limited to the filter material 41 as long as it has a function of preventing the tobacco shred 21 from entering the filter 4. For example, a mesh material made of metal, resin, or the like, and various configurations can be adopted as the tobacco shred overflow suppressing means. However, by using the tobacco shred overflow suppressing means as the filter material 4 as in the present embodiment, the material cost of the filter 4 can be reduced, and the complication of the manufacturing process can be prevented.

Further, in the present embodiment, the ventilation holes 31 of the filter 4 are arranged at positions corresponding to the filter segments S1. With this structure, ventilation air can be smoothly introduced into the filter 4 through the ventilation holes 31. In addition, the vent hole 31 is disposed in the filter section S1. Further, as in the present embodiment, by disposing the ventilation holes 31 on the upstream side of the mouth end section S3, the mainstream smoke flowing through the first central hole 42a of the front section S2 is made to pass more easily toward the center of the first central hole 42a by the flow of ventilation (dilution) air introduced into the filter 4 from the ventilation holes 31. That is, the flow of the air flowing in from the ventilation hole 31 is made closer to the outer peripheral side of the first center hole 42a, and the flow of the mainstream smoke is made closer to the center side of the first center hole 42a, and in this state, they are made to flow to the downstream side. This flow of the mainstream smoke and the dilution air is maintained even when passing through the second central hole 43a of the nozzle end section S3, and therefore, the effect of reducing the frequency of contact between the mainstream smoke sucked into the oral cavity from the rear end of the second central hole 43a and the nozzle end face is further enhanced. Therefore, tar contamination on the mouth end surface of the filter 4 can be made more inconspicuous. The above-described "passing mainstream smoke toward the center side of the first central hole 42 a" effect can be obtained by disposing the ventilation holes 31 on the upstream side of the mouthpiece end section S3 of the filter 4.

Therefore, instead of disposing the vent hole 31 at a position corresponding to the front section S1, the vent hole 31 may be disposed at a position corresponding to the front section S2 as appropriate, as in the configuration example shown in fig. 6. Fig. 6 is a diagram illustrating another modification of the position where the vent hole 31 is disposed. In the example shown in fig. 6, the ventilation hole 31 is disposed at a position corresponding to the front section S2 of the filter 4. As shown in the figure, the ventilation holes 31 pass through not only the tipping paper 3 but also the side wall of the second central hole 43a surrounding the central hole filter 42. Further, similarly to the case where the ventilation holes 31 are disposed in the filter section S1, the mainstream smoke can be caused to flow toward the center of the central hole 42a by the flow of dilution air introduced from the ventilation holes 31 of the front section S2 into the second central hole 43a of the central hole filter 42, whereby tar contamination on the mouth end surface of the filter 4 can be made inconspicuous. In the configuration example shown in fig. 6, the ventilation holes 31 are formed in both the side wall of the central hole filter 42 and the tipping paper 3, but the ventilation holes 31 may be formed only in the tipping paper 3, and in this case, the air that has passed through the central hole filter 42 may be introduced into the second central hole 43 a.

Next, the diameters and lengths of the first central hole 42a and the second central hole 43a in the filter 4 will be described as examples. In the present embodiment, the diameter of the first central hole 42a in the front segment S2 (central hole filter 42) is set to a range of 26% to 39% of the diameter of the filter 4, for example. For example, in the case where the filter 4 has a normal size of 7.7mm in diameter, the diameter of the first central hole 42a may be set to 2mm to 3 mm. In the case where the filter 4 has an elongated size of 5.3mm in diameter, the diameter of the first central hole 42a may be 1.3mm to 2 mm.

On the other hand, as an example, the diameter of the second central hole 43a of the mouth end section S3 (central hole filter 43) is set to be larger than 39% and in a range of 78% or less of the diameter of the filter 4. For example, in the case where the filter 4 has a normal size of 7.7mm in diameter, the diameter of the second central hole 43a may be set to be larger than 3mm and 6mm or less. For example, in the case where the filter 4 has an elongated size of 5.3mm in diameter, the diameter of the second central hole 43a may be set to be larger than 2mm and not larger than 4.1 mm.

Further, for example, the front section S2 in which the central hole filter 42 is disposed has a length of 7mm or more, and the mouthpiece section S3 in which the central hole filter 43 is disposed has a length of 5mm or more and 10mm or less. In addition, as an example, the ratio of the diameter (diameter/length) in the nozzle end section S3 with respect to the length of the second central hole 43a is 0.3 or more and 1.2 or less. In view of making it difficult to identify the local tar contamination of the rear end face of the front segment S2 (center hole filter 42), the ratio of the diameter to the length of the second center hole 43a is preferably 1.2 or less.

Further, the sectional shapes of the first central hole 42a of the front section S2 and the second central hole 43a of the nozzle end section S3 are not limited to circles, and various shapes may be adopted. Here, when the cross-sectional shape of the first center hole 42a is not a circle, the first center hole 42a may be formed such that the diameter of a circumscribed circle of the first center hole 42a is 2mm to 3mm, for example. In addition, when the cross-sectional shape of the second center hole 43a is not a circle, the second center hole 43a may be formed so that the diameter of the inscribed circle of the second center hole 43a becomes larger than 3mm and 6mm or less.

< modification example >

Various modifications can be adopted for the filter 4 of the present embodiment. Next, a modified example of the filter 4 of the present embodiment will be described.

Fig. 7 is a longitudinal sectional view of a cigarette 1A according to modification 1. The filter 4A of the cigarette 1A is the same as the filter 4 shown in fig. 1, except that a charcoal filter section S0 including a charcoal (activated carbon) additional filter material 44 is disposed at the front stage of the filter section S1. A charcoal filter section S0, a filter section S1, a front section S2, and a mouthpiece section S3 are arranged in this order from the front end of the filter 4A. The charcoal additional filter material 44 provided in the charcoal filter section S0 is a charcoal filter in which a cellulose acetate fiber bundle to which activated carbon (for example, carbon from coconut shell of 20 to 80 Mesh) is added is wound by a winding paper. In addition, charcoal (activated carbon) acts as an adsorbent that adsorbs components of the smoke of the mainstream smoke.

In the present modification, the filter material 41 made of cellulose acetate fibers is continuously provided at the rear end of the charcoal addition filter material 44. Accordingly, the filter material 41 disposed at the rear stage of the charcoal addition filter material 44 can function as activated carbon overflow suppressing means for preventing the activated carbon added to the charcoal addition filter material 44 from entering the first central hole 42a of the front stage section S2 (central hole filter 42). Instead of disposing the filter material 41 at the rear end of the charcoal filter section S0, a metal or resin mesh material or the like may be disposed to function as the activated carbon overflow prevention means.

In the filter 4 shown in fig. 1, the front section S2 and the mouthpiece section S3 are disclosed as examples of sections having no filtering function, but sections having no filtering function, sections having a filtering function, and the like may be appropriately provided between the filtering section S1 and the front section S2. That is, in the filter 4 of the present embodiment, the cross-sectional area of the second central hole 43a as the through passage of the mouth end section S3 may be set larger than the cross-sectional area of the first central hole 42a as the through passage of the front section S2 located immediately upstream of the mouth end section S3, and various modifications may be adopted for the configuration on the upstream side of the front section S2 in the filter 4.

Fig. 8 is a longitudinal sectional view of a cigarette 1B according to modification 2. The filter 4B of the cigarette 1B of modification 2 is provided with center hole segments S4 and S5 additionally disposed between the filter segment S1 and the front segment S2 of the filter 4 shown in fig. 1. A central pore filter 45 having a third central pore 45a is disposed in the central pore section S4, and a central pore filter 46 having a fourth central pore 46a is disposed in the central pore section S5. In the filter 4B shown in fig. 8, the third central hole 45a, the fourth central hole 46a, the first central hole 42a, and the second central hole 43a are coaxially arranged. The flow path cross-sectional area of the mainstream smoke in each central hole increases in stages in the order of the third central hole 45a, the fourth central hole 46a, the first central hole 42a, and the second central hole 43 a. This modification also has the same effect as the filter 4 shown in fig. 1, that is, it is possible to make the tar contamination of the mouth end face of the filter inconspicuous and to prevent the filter from being insufficiently stiff.

Fig. 9 is a longitudinal sectional view of a cigarette 1C according to modification 3. The filter 4C of the cigarette 1C of modification 3 is provided with the central hole sections S4 and S5 of the filter 4B shown in fig. 8 replaced by the same positions. That is, in the filter 4C, the filter section S1, the central hole section S5, the central hole section S4, the front section S2, and the mouthpiece section S3 are arranged in this order from the front end side. In the filter 4C of modification 3, the mainstream smoke that has passed through the filter segment S1 flows into the fourth central hole 46a, and is drawn by the smoker after passing through the third central hole 45a, the first central hole 42a, and the second central hole 43a in this order. In the present modification, the cross-sectional area of the second central hole 43a of the mouth end section S3 is set to be larger than the cross-sectional area of the first central hole 42a of the front section S2 that is continuously provided just upstream of the mouth end section S3, so that tar contamination on the mouth end face of the filter is less noticeable, and insufficient hardness of the filter can be prevented, as in the case of the filter 4 shown in fig. 1.

While the preferred embodiments of the present invention have been described above, the filter-tipped cigarette according to the embodiments may be variously modified, improved, combined, and the like.

Description of the reference numerals

1. 1A, 1B, 1C cigarette

2 tobacco rod

3 connect the paper

4. 4A, 4B, 4C filter

S1 filtration section

S2 front segment

S3 suction nozzle end section

41 Filter Material

42. 43 centre hole filter

42a first central hole

43a second central hole

Claims

1. A filter cigarette comprising a tobacco rod containing tobacco shreds and a filter connected to an end of the tobacco rod via a tipping paper sheet,

the filter has:

the section of the suction nozzle end, which is configured at the suction nozzle end, is provided with a fiber bundle, and the fiber bundle forms a through passage for flowing of the main stream smoke along the axial direction;

a front section continuously arranged at the front end of the suction nozzle end section is provided with a fiber bundle, the fiber bundle forms a through passage for the main stream smoke to flow along the axial direction,

the cross-sectional area of the through passage of the nozzle end section is larger than that of the front section,

a filter material which is disposed at a tip end portion of the filter on the opposite side of the mouth end and which includes a fiber bundle for filtering mainstream smoke and has no through passage formed therein, and which is disposed as a tobacco shred overflow suppressing means for suppressing the entry of the tobacco shred into the filter,

the tipping paper sheet is provided with a vent hole for introducing outside air into the filter to dilute mainstream smoke,

the ventilation hole is disposed upstream of the mouth end section in the filter, and the air from the ventilation hole is introduced into the filter material disposed at the tip end section of the filter on the opposite side of the mouth end, then passes through the filter material, and is introduced into the through passage formed in the front section, or the air from the ventilation hole is directly introduced into the through passage formed in the front section.

2. The filter cigarette of claim 1,

the length of the nozzle end section is shorter than the length of the front section.

3. The filter cigarette of claim 1 or 2,

the nozzle end section and the front section are coaxially arranged.