JP5841671B1 - Cellulose acetate tow band for cigarette filter, cigarette filter, tow band manufacturing apparatus, and tow band manufacturing method - Google Patents

Abstract

In the cellulose acetate tow band for cigarette filter, the filament denier is 5.0 denier or more and the filament ferret area is 0.5 or more and / or the ratio S / L of the cross-sectional area S of the filament to the cross-sectional circumference L Is 5 or more. The filament denier may be 10 denier or less, the ferret area may be 0.9 or less, and the ratio S / L may be 9 or less. In the tow band manufacturing apparatus or manufacturing method, a circular spinning hole (10) having a diameter of 50 μm or more is used. The diameter of the circular spinning hole (10) may be 100 μm or less.

Description

  The present invention relates to a cellulose acetate tow band, a cigarette filter produced from the tow band, and an apparatus and method for producing the tow band.

  Cellulose acetate tow band is well known as a cigarette filter material. In the production of tow band, the spinning dope is prepared by dissolving cellulose acetate in an organic solvent. The spinning machine includes a plurality of spinning cylinders, and each spinning cylinder includes a spinneret having a large number of spinning holes. In each spinning cylinder, a spinning dope is discharged from a large number of spinning holes to form a large number of filaments, and a large number of filaments are collected to form a yarn. A tow band is manufactured by uniting yarns from all spinning cylinders and crimping them. In the manufacture of cigarette filters, filter rods are manufactured from tow bands. The filter rod is manufactured by opening a tow band, adding a plasticizer such as triacetin to the band, forming the cylindrical shape into a cylindrical shape, and winding it with a wrapping paper. Cigarette filters are manufactured by cutting filter rods to a predetermined length.

  In this document, a “filament” is a single fiber (single fiber) extruded from a single spinning hole. A “yarn” is a single fiber bundle (aggregate of single fibers) in which a large number of filaments formed by a single spinning cylinder are combined. The “tow band” is a fiber bundle in which all yarns corresponding to a spinning cylinder, that is, all filaments formed by a spinning machine are combined. The toe band is an aggregate of a large number of filaments that have been crimped in a narrow sense. In the description related to the prior art, the fiber bundle or aggregate defined in this way may be referred to as “filter tow” or simply “tow” instead of “tow band”.

  “Filament denier” is the fineness of a filament expressed by mass (g) per unit length (9000 m), and may be abbreviated as “FD” hereinafter. In other words, the FD of the tow band means the fineness of one filament constituting the tow band. “Total denier” is the fineness of the tow band expressed by mass (g) per unit length (9000 m), and may be abbreviated as “TD” hereinafter. The “clogging amount” is the net weight of the tow band filled in one filter rod.

  In the past, Y-shaped and other irregular shapes have been preferred for the cross-sectional shape of the filament. For example, in Patent Document 1, an H-shaped filament is prepared using a spinneret having a square orifice, and the bundle is used for a cigarette filter or the like.

  In recent years, thin cigarettes called “slim type” or “super slim type” are commercially available. If a thin cigarette filter is made of a conventional material as disclosed in Patent Document 1, the ventilation resistance becomes too high. In recent years, cigarettes having filters embedded with capsules containing flavor components are also commercially available. Capsules cause an increase in ventilation resistance. High ventilation resistance makes it difficult for smokers to smoke cigarettes. Therefore, there is a demand for a material that can reduce the ventilation resistance even when it is used in the cigarette filter as described above.

  For example, Patent Document 2 discloses a cigarette having a narrow winding size. The cigarette includes a filter including a filter member and a winding paper wound around the filter member, and a chip paper adhered on the cigarette rod and the filter so as to connect the cigarette rod and the filter. A through hole is formed so as to penetrate the chip paper and the web and allow air to flow in during smoke absorption. The filter member includes tow, which has an FD greater than 8.0 denier and a TD less than 15000 denier, which in combination with the through-hole is intended to reduce the airflow resistance. Further, it is presumed that the airflow resistance is lowered by reducing the amount of clogging.

US Pat. No. 2,825,120 International Publication No. 2013/042609

  If the amount of clogging is lowered, the ventilation resistance can be lowered. However, the hardness of the cigarette filter is also lowered at the same time. Then, since a cigarette filter becomes easy to deform | transform during smoking, a smoker becomes difficult to smoke a cigarette. Moreover, since the air inflow amount from the cigarette tip decreases instead of the air inflow amount from the through hole increasing, there is a problem that the amount of tar generated by smoking decreases.

  Further, in Patent Document 2, TD is reduced to provide a volume suitable for the super slim type, and FD is increased to reduce the airflow resistance that rises as it becomes thinner. As a result, the number of filaments constituting the tow is inevitably reduced. However, if the TD is small and the number of filaments is small, it is difficult to crimp the tow uniformly in its length and width directions, and it is difficult to stabilize the quality of the tow. If the crimp is not constant, the ventilation resistance of the cigarette filter also fluctuates, making it difficult to stabilize the quality of the cigarette filter.

  Therefore, the present invention produces a cigarette filter capable of suppressing the airflow resistance and its fluctuation while maintaining hardness, a tow band of cellulose acetate that produces such an action when used as a cigarette filter, and such a tow band. It is an object of the present invention to provide an apparatus and method.

  The tow band of cellulose acetate for a cigarette filter according to one embodiment of the present invention is formed by crimping a plurality of filaments discharged from each of a plurality of spinning holes into a bundle, and having a filament denier of 5.0. Denier or higher, and the filament ferret area is 0.5 or higher.

  The “Feret area” is an index that can be used to evaluate the irregularity of the filament cross section. In deriving the ferret area, a section is taken by cutting the filament perpendicularly to the filament major axis direction at an arbitrary point, and a parallelogram circumscribing the section is assumed (see FIG. 5). In this virtual parallelogram, one of the two pairs of opposite sides is two lines circumscribing the cross section and the distance between the lines is a maximum value (so-called maximum Feret diameter), The other is two parallel lines circumscribing the cross section, and the distance between the lines is the minimum value (so-called minimum Feret diameter). The ferret area is an area ratio obtained by dividing the cross sectional area of the filament by the area of the virtual parallelogram, in other words, the occupation ratio of the filament cross section in the virtual parallelogram.

  The technical significance of the filament ferret area in the cigarette filter field will be described below. In general, in the cigarette filter, the long axis direction of the filament is oriented substantially perpendicular to the mainstream smoke flow of the cigarette (see FIG. 6). The mainstream smoke is blocked by the filaments arranged in this manner, and droplets contained in the mainstream smoke collide with the filament and are collected. In light of this cross flow, it can be said that the blocking ability of the filament is substantially equivalent to the blocking ability of the virtual filament whose cross-sectional shape is a parallelogram imaginary when the ferret area is derived. Therefore, a small ferret area indicates that the filament blocking ability is high with respect to the cross-sectional area of the filament. Since the cross-sectional area of the filament is positively correlated with the mass of the tow band (tow filling weight), a small ferret area indicates that a large amount of mainstream smoke can be blocked with a small tow band mass.

For example, in the case of a filament having a perfect circular cross section, the virtual parallelogram is a square whose length is equal to the diameter of the perfect circular cross section, so that the ferret area is πr ² / 4r ² , that is, about 0.785 ( Conventionally, r is a radius of a perfect circular cross section). However, such a filament is considered to be an inefficient material that does not have excellent collection performance for its mass, and attempts have been made to reduce the ferret area. As part of that, attempts have been made to deform the cross-section, and as described above, a modified spinning hole and a modified cross-section have been preferred. For example, in a filament having a Y-shaped cross section formed by using a triangular spinning hole or a Y-shaped spinning hole, the Y-shaped cross section corresponds to a shape obtained by partially contracting and deforming a triangle, so that the ferret area is less than 0.5. Become. Thus, when the profile irregularity becomes remarkable, the ferret area becomes small.

  In the process of developing a cellulose acetate tow band for a cigarette filter in order to achieve the above object, the present inventor, contrary to the previous development concept, forms a tow band with a relatively large ferret area filament. It was conceived that the tow band can further reduce the blocking ability and reduce the ventilation resistance by that amount even under the same mass conditions as those of the conventional tow band made of a filament having a deformed cross section.

  According to the tow band according to the embodiment of the present invention, since the filament is relatively large as 5.0 or more, ventilation resistance can be suppressed. Further, the ferret area of the filament is 0.5 or more, which is larger than the filament ferret area having a Y-shaped or H-shaped cross section which has been generally used in the past, and the deformity is suppressed. Accordingly, when the tow band cigarette filter is put into practical use, the ventilation resistance can be suppressed compared to the mass (even if the tow filling weight is increased). Further, when this tow band is used as a cigarette filter, air smoothly flows along the outer surface of the filament in the cigarette filter, and airflow resistance is suppressed. And since the ventilation resistance is suppressed, it becomes possible to keep a large number of filaments.

  Thus, by using a filament having a relatively large ferret area, when it is used as a cigarette filter, airflow resistance can be suppressed. For this reason, it is not necessary to reduce the amount of stuffing, and the hardness of the cigarette filter can be maintained high. Further, the total denier need not be particularly reduced, and therefore the number of filaments constituting the tow band can be reduced, and a stable crimping process can be performed on the tow band. Therefore, the quality and productivity of the tow band can be increased. And when a cigarette filter is manufactured using this tow band as a raw material, ventilation resistance and its fluctuation | variation can be suppressed, maintaining hardness high.

  The filament denier may be 10 denier or less. The ferret area may be 0.9 or less.

  The total denier may be 14,000 denier or more. The total denier may be 22,000 denier or less. Preferably, the total denier is 15000 to 21000 denier, more preferably 15000 to 20000, denier.

  The cellulose acetate tow band for a cigarette filter according to another embodiment of the present invention is formed by crimping a plurality of filaments discharged from each of a plurality of spinning holes into a bundle, and having a filament denier of 5.0. Density or more, and the ratio S / L of the area and the circumference when the area of the cross section of the filament is S and the circumference of the cross section is L is 5 or more.

  The “ratio S / L” is also an index used for evaluating the irregularity of the filament cross section, like the ferret area. If droplets contained in mainstream smoke are regarded as aerosols, it can be considered that the surface of the filament collects them. In that case, the smaller the ratio S / L, the higher the collection performance with respect to the cross-sectional area of the filament and thus the towed weight. If the profile of the filament cross-section is significant, the ratio S / L becomes small. The present inventor has discovered that the ratio S / L can be controlled within an appropriate range by setting the filament denier within a specific range.

  According to the tow band according to the other embodiment of the present invention, since the filament denier is relatively large as 5.0 or more, the airflow resistance can be suppressed and the ratio S / L is reduced because the filament denier is in such a range. It can be controlled to an appropriate range of 5 or more. Furthermore, since the ratio S / L is 5 or more, when this tow band is used as a cigarette filter, the ventilation resistance can be suppressed as compared with the tow filling weight. For this reason, it is not necessary to reduce the amount of clogging, the total denier, and the number of filaments. Therefore, the productivity of the tow band can be increased, and when a cigarette filter is manufactured from this tow band, the ventilation resistance and its fluctuation can be suppressed while maintaining the hardness high.

  The filament denier may be 10 denier or less, and the ratio S / L may be 9 or less.

  The cigarette filter which concerns on one form of this invention is manufactured from the said tow | toe band, and has a circumferential length of 14-18 mm, Preferably it is 14-17 mm, More preferably, it is 14-15 mm. Thereby, even if it is a thin cigarette, ventilation resistance and its fluctuation | variation can be suppressed, maintaining the hardness of a cigarette filter high.

  An apparatus for producing a tow band of a cellulose acetate for a cigarette filter according to one aspect of the present invention is for a cigarette filter, wherein a plurality of filaments discharged from each of a plurality of spinning holes are combined into a bundle and crimped. An apparatus for producing a tow band of cellulose acetate, comprising a spinneret having the plurality of spinning holes, wherein the spinning holes are circular and the diameter thereof is 50 μm or more.

  A method for producing a tow band of cellulose acetate for a cigarette filter according to one aspect of the present invention includes a step of discharging a spinning stock solution from each of a plurality of spinning holes to form a plurality of filaments, and combining the plurality of filaments. And forming a tow band by crimping, wherein the spinning hole is circular and has a diameter of 50 μm or more.

  If the spinning hole has such a size, the filament denier is increased and the change in the cross-sectional shape is increased, so that the spinning hole is circular. Therefore, a filament having a filament denier of 5.0 denier or more and having a relatively smooth cross-sectional shape having a ferret area of 0.5 or more and / or a ratio S / L of 5 or more is formed. Can do.

  The spinning hole may be circular and the diameter may be 100 μm or less. As a result, a filament having a filament denier of 10 denier or less and a ferret area of 0.9 or less and / or a ratio S / L of 9 or less can be formed.

  ADVANTAGE OF THE INVENTION According to this invention, the tow band of a cellulose acetate which produces such an effect | action when used as a cigarette filter which can suppress ventilation resistance and its fluctuation | variation while maintaining hardness, and a cigarette filter can be provided. In addition, an apparatus and method for manufacturing such a tow band can be provided.

It is a conceptual diagram which shows the apparatus and method for manufacturing the tow | toe band of the cellulose acetate for cigarette filters which concern on embodiment. It is a bottom view of the spinneret which concerns on embodiment. It is a figure which shows the cross section of the filament which concerns on embodiment. It is explanatory drawing of the parameter | index for evaluating the irregularity of a filament cross section. (A) shows an example of the cross section of the filament which concerns on embodiment, (b) shows a comparative example. It is a figure explaining the derivation method of a ferret area. It is a figure which shows an example of the flow of the cigarette mainstream smoke within a cigarette filter.

  Hereinafter, embodiments will be described with reference to the drawings. The same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and redundant description thereof is omitted.

  FIG. 1 is a conceptual diagram showing an apparatus and a method for producing a cellulose acetate tow band TB for a cigarette filter according to an embodiment. As shown in FIG. 1, the tow band manufacturing apparatus 1 includes a mixer 2, a filter 3, a spinning machine 4, a crimper 5, a dryer 6 and a packing machine 7. In the production of tow bands, a stock solution for spinning (hereinafter sometimes simply referred to as “dope”) is prepared (stock solution preparation step). In the stock solution preparation step, cellulose acetate is dissolved in an organic solvent such as acetone in the mixer 2 to prepare a solution having a required concentration (for example, a weight concentration of 20 wt% to 30 wt%, preferably 26 wt%). Next, the solution is filtered by the filter 3. This filtrate is used as the spinning dope.

  After the stock solution preparation step, the cellulose acetate tow band TB is produced from the spinning stock solution using the spinning machine 4, the crimper 5 and the dryer 6 (spinning step). The tow band TB is compressed and packed by the packing machine 7 (packing process).

  Although not shown in detail, the cigarette filter is manufactured using the toe band TB as a material. In manufacturing a cigarette filter, a filter rod is manufactured as an intermediate product. That is, the tow band TB is opened and a plasticizer such as triacetin is added. The tow band TB is formed into a cylindrical shape suitable for the size (diameter and circumferential length) of the target cigarette using a plug hoist, and the wrapping paper is wound around the filter rod. The filter rod manufactured in this way is cut into a predetermined length according to the target cigarette. Thereby, a plurality of cigarette filters are manufactured from one filter rod.

  The tow band TB according to the present embodiment is suitable for a cigarette filter material to be attached to a thin cigarette such as a so-called slim type or super slim type. The cigarette filter has a circumferential length of 14 mm or more and 18 mm or less (preferably 14 to 17 mm, more preferably 14 to 15 mm or less), for example.

  The spinning process and the devices 4 to 6 used for the execution will be described. The spinning machine 4 includes a plurality of spinning cylinders 11 and a plurality of spinning caps 12 corresponding to the respective spinning cylinders 11. The spinning cylinder 11 is a long cylinder in the vertical direction, and the spinneret 12 is provided at the upper end of the spinning cylinder 11. The spinneret 12 has a plurality of spinning holes 10 (see FIG. 2).

  The spinning dope is fed into a plurality of spinnerets 12 by a spinning pump 13. In each spinning cylinder 11, the spinning dope is discharged downward into the spinning cylinder 11 from each of the plurality of spinning holes of the spinneret 12, and a plurality of filaments F are formed by a dry spinning method. As the plurality of filaments F are directed downward, the distance between each other is reduced, whereby one yarn Y is formed. The yarn Y is discharged downward from the bottom of the corresponding spinning cylinder 11. In the spinning machine 4, the plurality of yarns Y are discharged from the plurality of spinning cylinders 11, respectively.

  Each yarn Y is given an oil emulsion containing fiber oil and water from the oiling device 14, passes around the godet roller 15, and is sent to the crimper 5. The plurality of yarns Y are united with each other in the process from the godet roller 15 toward the crimping machine 5, thereby forming a toe band TB. The crimper 5 is, for example, a known stuffing box type. The tow band TB is fed into a stuffer box while being pressed by a pushing roll. Thereby, the crimp of the waveform is given to the toe band TB. The crimped tow band TB (tow band in a narrow sense) is sent from the crimper 5 to the dryer 6. In the dryer 6, residual solvent and moisture are removed from the tow band TB.

  The process of forming cellulose acetate filaments by dry spinning will be described. The spinning solution travels downward in the spinning cylinder 11 until it is discharged from a certain spinning hole and discharged from the spinning cylinder 11. At the start of running of the dope (that is, when the dope is discharged from the spinning hole), the dope is in a liquid phase. During running of the dope, the solvent evaporates from the dope to form a filament, and the dope changes from the liquid phase to the solid phase. The solvent evaporates from the dope surface immediately after the start of running.

  The cross-sectional shape of the filament is characterized by the relationship between the evaporation rate, which is the rate at which the solvent evaporates from the dope surface, and the diffusion rate, which is the rate at which the solvent diffuses from the dope center to the surface. Evaporation rate is: (1) solvent retention of cellulose acetate, (2) vapor pressure of solvent at ambient temperature, (3) saturation by atmospheric vapor of solvent gas at each running point, (4) discharge of spinning solution Depends on factors such as speed and (5) evaporation surface area. The diffusion rate follows Fick's second law.

  Immediately after the start of the dope running, the diffusion from the center of the dope does not catch up with evaporation on the surface of the dope, and the dope surface layer is solidified to form a skin. When the skin is formed, the cross-sectional circumference of the filament is determined to some extent. The solvent in the center of the dope diffuses in the skin and evaporates. For this reason, the volume in the skin (that is, the cross-sectional area of the filament) is reduced after the skin is formed, and the skin is deformed in the radial direction. Therefore, the cross section of the filament exhibits a shape deformed from the shape of the spinning hole.

  The present inventors have found out as follows. That is, when the diameter of the spinning hole is small, most of the solvent in the center of the dope diffuses and evaporates at the stage where the skin is formed. Therefore, the filament cross-sectional shape does not change greatly from the shape of the spinning hole. For example, if the spinning hole is circular, the cross section of the filament is substantially circular and its deformity is small. If the profile of the cross section is small, it is difficult to secure filtration performance. In the past, filtration performance has been ensured by adopting an irregular shape for the spinning hole and an irregular shape such as a Y shape or an H shape for the filament cross section.

  The factors (1) to (4) are almost determined by the process. That is, (1) depends on the solvent used, (2) the atmospheric temperature depends on the drying temperature in the process, (3) is determined by the amount of drying air, and (4) is determined by the production capacity such as the spinning speed. On the other hand, regarding the factor (5), if the diameter of the spinning hole is large, the cross section of the filament also becomes large and the evaporation surface area becomes large. When the evaporation surface area is large, the evaporation rate increases and the irregularity of the filament cross section becomes stronger. In addition, when the diameter of the spinning hole is large, the volume of the solvent confined in the skin increases. Also from this point, the irregular shape of the filament cross section becomes stronger.

  Therefore, if the diameter of the spinning hole is kept within a specific range and the shape of the spinning hole is circular, the irregular shape of the filament cross section can be controlled to ensure a certain filtration performance. In other words, if the diameter of the spinning hole is small, the Y-shaped or H-shaped irregular cross section, which was preferable, is not used, but if the spinning hole having a circular diameter in a specific range is used, the filament has a suitable irregular shape. The ventilation resistance is appropriately controlled by a filament having a specific FD that can be expressed and has such an irregularity.

  FIG. 2 is a bottom view of the spinneret 12 according to the embodiment. As shown in FIG. 2, the plurality of spinning holes 10 are opened at the bottom surface 12 a of the spinneret 12 facing the spinning cylinder 11. As an example, the bottom surface 12a is circular, and the plurality of spinning holes 10 may be arranged in an annular shape on the bottom surface 12a. However, the shape of the bottom surface 12a and the arrangement of the spinning holes 10 can be changed as appropriate. The spinning hole 10 is circular and has a diameter of 50 μm or more and 100 μm or less. More preferably, they are 50 micrometers or more and 90 micrometers or less.

  FIG. 3 is a diagram illustrating a cross section of the filament F according to the embodiment. The cross section is obtained by cutting the filament F perpendicularly to the filament major axis direction. The FD of the filament F is not less than 5.0 denier and not more than 10 denier. More preferably, it is 5.5 denier or more and 9.0 denier or less. By using the spinning hole 10 described above, the FD of the tow band TB can be within such a numerical range.

  Since the diameter of the spinning hole 10 falls within the specific range described above, the deformed shape of the cross-sectional shape of the filament F discharged from the spinning hole 10 is controlled to an appropriate range. Although the cross-sectional shape of the filament F is not a perfect circle, its deformity is suppressed as compared with the Y shape and the H shape, and it has a shape approximate to a circle.

  FIG. 4 is an explanatory diagram of an index for evaluating the irregularity of the filament cross section. FIG. 4A is an example of a cross section of the filament F according to the embodiment, and FIG. 4B is a comparative example, which is a Y-shaped filament formed using a spinneret having a triangular or Y-shaped spinning hole. It is an example of the cross section of Fy. The index is, for example, “Ferre area” or “Ratio S / L”.

  “Ferret area” is a ratio (S / SVP) of the area S to the area SVP when the cross-sectional area of the filament F is S and the area of the virtual parallelogram VP circumscribing the cross-section is SVP. In this virtual parallelogram, one of the two pairs of opposite sides is two parallel lines circumscribing the cross section, and the distance between the lines is the maximum ferret diameter. The other is two parallel lines circumscribing the cross section, and the distance between the lines is the minimum ferret diameter. Therefore, when the cross section of the filament F is taken at an arbitrary point and the ferret area of the cross section is obtained, the ferret area has a value that does not depend on the posture around the normal line of the cross section. If the cross section is a perfect circle, the ferret area is 0.785 [-], and if it is a triangle, the ferret area is 0.5 [-] or less.

  The cross section of the filament F is very small. However, by setting the virtual parallelogram VP circumscribing the filament cross section by processing electronic data of an image captured through a microscope using a known image processing technique or by manually calculating based on the captured image, Measurements of cross-sectional area S, area SVP, and cross-sectional circumference L can be performed.

  As shown in FIG. 4B, in the Y-shaped filament Fy according to the comparative example, the region excluding the inscribed circle ICy in the cross section has a plurality of locations (three locations) on the circumference of the inscribed circle ICy. It is remarkable that the plurality of portions protrude outward from the circumferential direction and are separated in the circumferential direction. On the other hand, the virtual parallelogram VPy must be set so as to surround the region. Therefore, the virtual parallelogram VPy is separated from the inscribed circle ICy in the radial direction and becomes very large compared to the size of the inscribed circle ICy. The area only occupies a very small part of the space excluding the inscribed circle ICy from the virtual parallelogram VPy. Therefore, in the Y-shaped filament according to the comparative example, the ferret area is a small value. Since the Y shape is a contraction of the spinning hole triangle, the ferret area is less than 0.5. Further, since the degree of unevenness at the outer edge of the cross section is large, the cross section circumferential length L is larger than the cross sectional area S and the ratio S / L is also a small value.

  On the other hand, as shown to Fig.5 (a), in the filament F which concerns on this embodiment, it forms using a circular spinning hole, and the unevenness | corrugation in the cross-sectional outer edge part is small. The region excluding the inscribed circle IC in the cross section of the filament F is formed over substantially the entire circumference. The amount of outward protrusion from the inscribed circle IC does not vary greatly with respect to the circumferential direction of the inscribed circle IC. For this reason, the virtual parallelogram VP is close to the inscribed circle IC in the radial direction. Thus, in the filament F which concerns on embodiment, the ferret area becomes a comparatively large value because the deformity of the cross-sectional shape is suppressed. Moreover, the unevenness | corrugation of a cross-section outer edge part is small, and ratio S / L becomes a large value.

  In the present embodiment, the spinning hole 10 having a diameter of 40 μm or more is used, and the FD of the tow band TB is 5.0 denier or more, which is larger than a conventional one. When the FD increases, the ventilation resistance can be suppressed when the tow band TB is used as a cigarette filter.

  Moreover, in this embodiment, the circular spinning hole 10 is used and the ferret area of the filament F is 0.5 or more and 0.9 or less. The ratio S / L is 5 or more and 9 or less. Since the torsional property of the filament cross section is suppressed, when this tow band TB is used as a cigarette filter, the airflow resistance can be suppressed even if TD is large.

  As described above, if the diameter of the spinning hole 10 and the FD of the toe band TB are too large, the irregularity appears remarkably. If the FD of the toe band TB becomes too large, it is necessary to reduce the number of filaments constituting the toe band TB in order to adjust the TD of the toe band TB.

  Therefore, the diameter of the spinning hole 10 is set to 100 μm or less, and the FD of the tow band TB is set to 10 denier or less. The diameter of the spinning hole 10 is more preferably 50 μm or more and 90 μm or less, and the FD of the tow band TB is more preferably 15,000 denier or more and 22,000 denier or less. Thereby, a ferret area can be 0.6 or more and 0.8 or less. Further, the ratio S / L can be set to 5.5 or more and 8.0 or less.

  As described above, in the present invention, it is possible to suppress an increase in ventilation resistance by keeping the FD at a certain size and suppressing the deformity. Furthermore, in the present invention, even if the amount of filter clogging is increased, the degree of increase in ventilation resistance is low. For this reason, the fluctuation | variation of the ventilation resistance of a cigarette filter by the fluctuation | variation of the clogging amount of a cigarette filter can be suppressed. Therefore, the amount of cigarette filter clogging can be increased, and the filter hardness can be maintained. In this way, a cigarette filter manufacturer can manufacture a cigarette filter without changing the manufacturing conditions depending on the type of cigarette, and the productivity of the cigarette filter is improved.

  Furthermore, in the present invention, the TD of the tow band TB can be kept high. For example, the TD of the tow band TB can be 14,000 denier or more and 22,000 denier or less, preferably 15,000 denier or more and 21,000 denier or less. Thus, even if TD is maintained high, ventilation resistance can be suppressed when used as a cigarette filter. Furthermore, since the TD of the tow band TB is maintained high, the volume of the tow T that is fed into the crimper 5 per unit time is also increased. Therefore, it becomes easy to supply tow T stably in the crimper box and to impart crimp to tow T. In this way, in the present invention, variation in ventilation resistance due to variation in the number of crimps of the tow band TB can also be suppressed.

  In the tow band TB according to the present embodiment, the tow band TB is formed such that the ferret area and / or the ratio S / L satisfies the above numerical range so that the FD satisfies the above numerical range. As a result, fluctuations in ventilation resistance can be satisfactorily suppressed. The variation of the ventilation resistance of the cigarette filter (plug) using the tow band TB according to the present embodiment is 4.0%, preferably 3.8, more preferably 3.5. More preferably, it can be made 3.2% or less.

  Thus, without using strict production control, manufacturing a tow band TB that can suppress airflow resistance while maintaining hardness when used as a cigarette filter and suppresses fluctuations in TD and the number of crimps. Can do. By manufacturing a cigarette filter using this tow band TB, it is possible to maintain the cigarette filter with high hardness and to suppress fluctuations in ventilation resistance. In particular, this cigarette filter can be suitably used in recent “slim type” and “super slim type” cigarette filters, or filters in which capsules are embedded.

  Hereinafter, examples will be described, but the present invention is not limited to the following examples. In Examples and Comparative Examples, ferret area, ratio S / L, ventilation resistance, fluctuation value of ventilation resistance, and filter hardness were measured by the following methods.

(Ferre area)
A pencil-shaped filament sample was prepared from the tow band according to the example or the comparative example. That is, a part of the fiber bundle was extracted from the tow band, and the fiber bundle was wrapped with paraffin so that the fiber bundle was positioned at a portion corresponding to the pencil core. The filament sample prepared in this manner was sliced with a microtome to a thickness of 1 μm to 10 μm to obtain a sample section. The sample slice was observed with an optical microscope (“BX-51” manufactured by Olympus Corporation), and an image obtained by the observation was taken into an image processing apparatus. The image processing apparatus was allowed to set the virtual parallelogram VP circumscribing one filament cross section included in the image, and to measure the cross sectional area of the filament and the area of the virtual parallelogram VP. The ferret area was calculated by dividing the cross-sectional area of the filament by the area of the virtual parallelogram.

(Ratio S / L)
The sample section was observed with the optical microscope, the image obtained by the observation was taken into an image processing apparatus, and the image processing apparatus was made to measure the cross-sectional area and the perimeter of one filament cross section included in the image. . The ratio S / L was calculated by dividing the cross-sectional area by the perimeter.

(Ventilation resistance)
A filter rod sample was produced from the tow band according to the example or the comparative example. That is, a filter rod having a predetermined length and a predetermined clogging amount (net tow weight) by converging the tow band to a predetermined diameter using an existing manufacturing apparatus and fixing the tow band with a paper roll using a filter hoisting machine A sample was made. Air having a temperature of 22 ± 1 ° C. and a humidity of 60 ± 10% was passed through the filter rod sample at a flow rate of 17.5 cc / second, and the pressure difference [mmWG] (millimeter water gauge) at both ends of the filter was measured. In all of the examples and comparative examples, the filter rod sample does not have a through-hole penetrating the wrapping paper.

(Variation value of ventilation resistance)
A total of 300 filter rod samples are sampled at intervals of 1 in 15. The fluctuation values were displayed as percentages from the measured values of 300 airflow resistances.

(Filter hardness)
The filter hardness was measured using a hardness meter (“QTM7” manufactured by Filtrona) for a filter rod sample molded to have a plug length of 120 mm, a circumference of 16.70 mm, and a ventilation resistance of 350 mmWG. . When measuring the hardness of the filter, a load of 300 g was applied vertically to the side surface of the filter rod sample. The filter hardness was calculated from the following equation.

Filter hardness [%] = d / d0 × 100
d is the diameter in the load direction of the filter rod sample after deformation due to load, and d0 is the diameter of the filter rod sample before deformation. If there is no deformation at all, the hardness is 100%, and the closer the hardness is to 100%, the harder it is.
(Examples 1-2)
The tow band according to Example 1 was manufactured as follows. That is, cellulose diacetate having an average degree of acetylation of 55.2% was dissolved in acetone to prepare a spinning dope having a concentration of about 25% by mass. A stock solution for spinning at a temperature of 50 to 60 ° C. was supplied to the spinneret. Each spinning hole is circular with a diameter of 71 μm. The stock solution for spinning was discharged from each spinneret into a spinning cylinder to form a filament of FD: 8.6 denier. In the spinning cylinder, heated air of 120 to 150 ° C. was applied to the filament to evaporate acetone. An oil emulsion was applied to the bundle-like aggregate (yarn) discharged from the spinning cylinder, and this was wound up with a godet roller. The yarns were united to form a tow band of TD: 21,000 denier. The tow band was crimped and the tow band was dried with a dryer. The tow band according to Example 2 was manufactured in the same manner as in Example 1 except that a filament of FD: 6.0 denier was formed using a circular spinning hole having a diameter of 59 μm.
(Comparative Examples 1-7)
The tow band according to Comparative Example 1 was manufactured in the same manner as in Example 1 except that a filament of FD: 2.0 denier was formed using a triangular spinning hole having a side of about 45 μm. The tow band according to Comparative Example 2 was produced in the same manner as in Example 1 except that a triangular spinning hole having a side of about 55 μm was used to form a FD: 3.0 denier filament. The tow band according to Comparative Example 3 was manufactured in the same manner as in Example 1 except that a filament of FD: 6.0 denier was formed using a triangular spinning hole having a side of about 80 μm. The tow band according to Comparative Example 4 was produced in the same manner as in Example 1 except that a filament having an FD of 7.0 denier was formed using a triangular spinning hole having a side of 85 μm. The tow band according to Comparative Example 5 was manufactured in the same manner as in Example 1 except that a filament of FD: 8.6 denier was formed using a triangular spinning hole having a side of about 95 μm. The tow band according to Comparative Example 6 was produced in the same manner as Comparative Example 3 except that the TD was 17,000. The tow band according to Comparative Example 7 was produced in the same manner as in Example 1 except that a triangular spinning hole having a side of about 95 μm was used to form a filament of FD: 8.0 denier and TD was 15000.

  A filter rod sample having a plug length of 120 mm, a circumference of 16.70 mm, and a tow packing weight of 0.35 g / rod was produced from the tow bands according to Examples 1 to 2 and Comparative Examples 1 to 7 and produced. The filter rod sample was stored in an air-conditioned room at a temperature of 20 ° C. and a humidity of 65% for 24 hours to adjust the humidity.

  About the obtained sample, ventilation resistance and its fluctuation value were measured by the said measuring method. Moreover, the filter hardness was measured with the said measuring method about the sample which concerns on Example 1 and Comparative Example 7. FIG. Table 1 shows the measurement results.

実施例１〜２及び比較例１〜５に係るトウバンドから、トウ詰込重量を０．３３ｇ／ｒｏｄとするフィルターロッドサンプルも作製した。比較例６に係るトウバンドから、トウ詰込重量を０．３３、０．２８ｇ／ｒｏｄとするフィルターロッドサンプルも作製した。比較例７に係るトウバンドから、トウ詰込重量を０．３３、０．２８、０．２４ｇ／ｒｏｄとするフィルターロッドサンプルも作製した。得られたサンプルについて通気抵抗を上記測定方法で測定した。表２はその測定結果を示す。

Filter rod samples having a tow filling weight of 0.33 g / rod were also produced from the tow bands according to Examples 1 and 2 and Comparative Examples 1 to 5. From the tow band according to Comparative Example 6, filter rod samples having a tow filling weight of 0.33 and 0.28 g / rod were also produced. From the tow band according to Comparative Example 7, filter rod samples having tow filling weights of 0.33, 0.28, and 0.24 g / rod were also produced. The ventilation resistance of the obtained sample was measured by the above measuring method. Table 2 shows the measurement results.

実施例１（8.6Ｒ21000）と比較例５（8.6Ｙ21000）の対比から明らかな通り、三角型紡糸孔では、ＴＤを２１，０００デニールとすると、ＦＤを８．６デニールまで太くしても、プラグ長さ１２０ｍｍ、円周１６．７０ｍｍで達成できる通気抵抗が４３０ｍｍＷＧ程度である。

As is clear from the comparison between Example 1 (8.6R21000) and Comparative Example 5 (8.6Y21000), if the TD is 21,000 denier in the triangular spinning hole, even if the FD is increased to 8.6 denier, the plug The ventilation resistance that can be achieved with a length of 120 mm and a circumference of 16.70 mm is about 430 mmWG.

  When it is desired to achieve a ventilation resistance of about 300 mmWG, it is necessary to reduce the TD at the triangular spinning hole. As in Comparative Example 7 (8.0Y15000), with TD15,000 denier and FD8.0 denier, the ventilation resistance is 530 mmWG. Therefore, it is necessary to reduce the ventilation resistance by reducing the clogging weight. If the stuffing weight is between 0.25 g and 0.28 g, a ventilation resistance of about 300 mmWG can be achieved. However, as described in Table 2, the hardness decreases as the clogging weight decreases (Comparative Example 7).

  On the other hand, a filament with a large ferret area can be obtained by making the spinning hole shape circular and increasing the filament denier. Even if the total denier is kept high with such a tow band, the ventilation resistance does not increase.

  As is clear from the comparison between Example 1 and Comparative Example 7, when the total denier is kept high, the fluctuation range of the ventilation resistance of the plug can be reduced.

  Furthermore, the variation in ventilation resistance due to weight variation is smaller than that in Comparative Example 7, and even when the clogging weight changes, the rate of change in ventilation resistance is small as is apparent from Example 1.

  For this reason, for example, in a tow band having a large FD using a circular spinning hole and a large TD using a filament having a large ferret area, it is possible to reduce the ventilation resistance by about 30% while maintaining the clogging weight. Thereby, the possibility of a hardness problem can be reduced, and the fluctuation | variation of ventilation resistance by the fluctuation | variation of the clogging weight at the time of plug winding can also be made small.

  The present invention is beneficial when used in a cellulose acetate tow band for cigarette filters.

F Filament TB Tow band 1 Tow band production device 4 Spinning machine 5 Crimping machine 10 Spinning hole 11 Spinning cylinder 12 Spinneret

Claims (8)

A cellulose acetate tow band for a cigarette filter, which is formed by crimping a plurality of filaments discharged from each of a plurality of spinning holes into a bundle.
The filament denier is 5.0 denier or more,
A cellulose acetate tow band for a cigarette filter, wherein the filament has a ferret area of 0.5 or more.   The cellulose acetate tow band for a cigarette filter according to claim 1, wherein the filament denier is 10 denier or less.   The cellulose acetate tow band for a cigarette filter according to claim 1 or 2, wherein the ferret area is 0.9 or less.   The tow band of cellulose acetate for a cigarette filter according to any one of claims 1 to 3, wherein the total denier is 14,000 denier or more.   The tow band of cellulose acetate for a cigarette filter according to claim 4, wherein the total denier is 22,000 denier or less. A cellulose acetate tow band for a cigarette filter, which is formed by crimping a plurality of filaments discharged from each of a plurality of spinning holes into a bundle.
The filament denier is 5.0 denier or more,
A toe band of cellulose acetate for a cigarette filter, wherein the area of the cross section of the filament is S and the ratio of the area and the peripheral length S / L is 5 or more when the peripheral length of the cross section is L.   The tow band of cellulose acetate for a cigarette filter according to claim 6, wherein the filament denier is 10 denier or less and the ratio S / L is 9 or less.   A cigarette filter manufactured from the tow band according to any one of claims 1 to 7 and having a circumferential length of 14 to 18 mm.

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