WO2012073737A1

WO2012073737A1 - Ultrafine polyamide fiber, and melt-spinning method and device therefor

Info

Publication number: WO2012073737A1
Application number: PCT/JP2011/076780
Authority: WO
Inventors: 健明河野; 小林　靖希; 純花岡
Original assignee: 東レ株式会社
Priority date: 2010-11-29
Filing date: 2011-11-21
Publication date: 2012-06-07
Also published as: KR20130141484A; JP5780237B2; US20130251992A1; CN103221589B; KR101580883B1; EP2647746B1; EP2647746A4; EP2647746A1; TW201231746A; JPWO2012073737A1; TWI527945B; CN103221589A

Abstract

This ultrafine polyamide fiber is a polyamide fiber having a single-filament fineness of 0.10-0.50 dtex, in which the average number of fluffs per 12,000 m of the length of the filaments is 1.0 or less. The melt-spinning method of the invention for producing the ultrafine polyamide fiber comprises: cooling melt-spun filaments discharged from a spinneret having orifices annularly disposed in the peripheral part of the spinneret, using a cooler (3) which is located under the center of the spinneret and which blows cooling air against the melt-spun filaments ejected from the orifices, from inside or outside the melt-spun filaments to cool the melt-spun filaments; oiling the filaments using an annular oiling device (4) that has a disk-shaped guide part which is located vertically under the cooler (3) and in which single filaments come into contact with the periphery of the disk and that has an annular slit for oil ejection which has been formed right over the guide part along the periphery of the guide; and then collecting the filaments and simultaneously performing second-stage oiling, by means of a collecting guide type oiling device (5).

Description

[Name of invention determined by ISA based on Rule 37.2] Polyamide ultrafine fiber and melt spinning method and apparatus thereof

The present invention relates to an ultrafine polyamide fiber having a very small single yarn fineness, and relates to a polyamide ultrafine fiber that can impart excellent softness, smoothness, drape, high water absorption, high density, and high quality after dyeing to a woven or knitted fabric. Is.

Polyamide fibers are widely used for clothing and industrial materials because they have many excellent properties including mechanical properties. Among the garment applications, false twisted yarn is widely used for woven fabrics, knitted fabrics, etc. In particular, an ultrafine false twisted yarn having a single yarn fineness of 1.2 dtex or less can provide a very soft texture when made into a fabric, and has better heat retention and water absorption than a normal single yarn fineness false twisted yarn. improves. Therefore, the market demand for ultra fine false twisted yarn is increasing and becoming a standard.

As the above-mentioned polyamide ultrafine fiber, by using a polyamide ultrafine fiber for false twisting that defines a friction coefficient, elongation, and hot water shrinkage in a fiber made of a polyamide resin having a single yarn fineness of 1.2 dtex or less, a fabric can be obtained. There has been proposed a polyamide ultrafine fiber for false twisting that can impart a soft feeling (Patent Document 1).

Further, in a polyamide fiber having a single yarn fineness of 1.2 dtex or less, by using a polyamide fiber for false twist that defines the stress at the time of 15% elongation of the yarn and the opening length of the interlace opening portion, the softness is excellent. There has been proposed a false twisting polyamide fiber from which false twisted crimped yarn can be obtained (Patent Document 2).

As a method for uniformly applying an oil agent to these polyamide ultrafine fibers, a so-called annular chimney is used, in which a polymer discharged from a spinneret in which discharge holes are arranged in a ring shape is blown with cold air from all directions on the inner or outer periphery of the yarn. It has been proposed that a single yarn is cooled uniformly by use, and an oil agent is applied by an oiling guide facing each other across the yarn (Patent Document 3).

Further, each single yarn is brought into contact with a plate arranged inside the plurality of filaments discharged from the discharge holes on the downstream side of the spinneret including the plurality of discharge holes arranged in an annular shape. A method of supplying an oil agent uniformly between yarns has been proposed (Patent Document 4).
Japanese Unexamined Patent Publication No. 2005-320655 Japanese Unexamined Patent Publication No. 2009-84749 Japanese Unexamined Patent Publication No. 2007-126759 Japanese Patent Application Laid-Open No. 2010-126846

However, if it is attempted to produce a very fine polyamide fiber having a single yarn fineness of 0.5 dtex or less by the method described in

Patent Documents

1 and 2, it becomes difficult to uniformly cool or apply a uniform oil agent. As a result of poor Worcester spots and fluff quality, and a large difference in fiber structure between single yarns, when used for false twisting, processing yarn breakage and unraveling occur, and when used for woven and knitted fabrics, There were drawbacks such as fuzz becoming prominent, the smoothness and quality of the fabric being lowered, and dyeing spots after dyeing being noticeably generated.

In order to solve such a problem, when an oil supply method described in Patent Document 3 is applied, the yarn is focused and an oil agent is applied. In the ultra-fine polyamide fiber with a single yarn fineness of 0.5 dtex or less, the strength per single yarn is reduced, the single yarns are scratched when the yarn converges, and the fiber before applying the oil agent has a large coefficient of friction. There is. For this reason, single yarn breakage due to rubbing between single yarns or rubbing between the single yarn and the guide before being applied with the oil agent, or even when the oil is evenly applied to the inner yarn of the converged yarn, it is difficult to apply the oil agent. The difference in adhesion between the oil agent and moisture occurs between the yarns and the fiber structure between the single yarns. Thus, there remains a defect that the quality after dyeing is lowered.

Furthermore, when trying to apply the method described in Patent Document 4, although uniform oil agent application between single yarns is excellent, uniform oil agent application in the longitudinal direction of the fiber is difficult, and oil agent adhesion variation in the longitudinal direction occurs, The structural difference and the friction coefficient variation of the fiber in the longitudinal direction increase. For this reason, in the spinning process and the high-order processing process, there was a disadvantage that tension variation occurred in the longitudinal direction due to rubbing with yarn guides and the like, dyeing spots were generated after dyeing, and a high-quality fabric could not be obtained. .

The object of the present invention is to solve the problems of the prior art described above, and to provide a woven or knitted fabric with excellent softness, smoothness, drape, high water absorption, high density, and high quality after dyeing. To provide fiber.

The present invention adopts the following configuration in order to solve the above problems.
(1) A polyamide ultrafine fiber characterized in that, in a polyamide fiber having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less, the average number of fluffs per 12000 m in the longitudinal direction of the filament is 1.0 or less.
(2) The polyamide ultrafine fiber as described in (1) above, wherein Worcester spots in the longitudinal direction of the filament are 1.0% or less.
(3) The polyamide ultrafine fiber as described in (1) or (2) above, wherein the total fineness is 15 to 300 dtex and the number of filaments is 30 or more.
(4) The polyamide ultrafine fiber as described in any one of (1) to (3) above, wherein the filament has an irregular cross-section.
(5) Polyamide ultrafine fiber having a single yarn with a circular cross-sectional shape of the filament, and the orientation parameter of the single yarn surface portion relative to the orientation parameter of the single yarn central portion with respect to the orientation parameter of the single yarn having a circular cross-sectional shape The polyamide ultrafine fiber according to any one of the above (1) to (3), wherein the ratio of is 1.10.
(6) A melt spinning method of polyamide ultrafine fibers having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and an average number of fluffs per 12000 m in the longitudinal direction of the filament of 1.0 or less, and the outer periphery of the spinneret A melt-spun yarn spun from a spinneret having discharge holes arranged circumferentially in the part, at the bottom of the center of the spinneret, inside the melt-spun yarn discharged from the discharge holes or A disk-shaped guide unit in which cooling is performed using a cooling device that blows cooling air from the outside to cool the melt-spun yarn, and a single yarn is in contact with the outer periphery of the disk at the lower part in the vertical direction of the cooling device, and a guide unit After supplying oil using an annular oil supply device having an annular slit for discharging an oil agent formed along the outer periphery of the guide, the yarn is converged by a converging guide type oil supply device and the second stage oil supply is performed. Melt spinning method of the polyamide ultrafine fiber characterized Ukoto.
(7) The polyamide according to (6), wherein the cooling device is a cooling device that cools the melt spun yarn by blowing cooling air from the inside of the melt spun yarn discharged from the discharge hole. A method for melt spinning ultrafine fibers.
(8) The melt spinning method for polyamide ultrafine fibers according to (6) or (7) above, wherein the cooling device satisfies the following conditions.
(I) The distance (L) from the spinneret surface to the cooling start position of the cooling device is 10 mm ≦ L ≦ 70 mm
(Ii) The speed of the cooling air blown out at the cooling start position is 15 to 60 m / min.
(9) A melt spinning apparatus for polyamide ultrafine fibers having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and an average number of fluffs per 12000 m in the longitudinal direction of the filament of 1.0 or less. Spinneret with discharge holes arranged circumferentially in the part, and melted by blowing cooling air from the inside or outside of the melt-spun yarn discharged from the discharge hole at the bottom of the center part of the spinneret A cooling device for cooling the spun yarn, and further, a disc-shaped guide portion in which the single yarn contacts the outer peripheral portion of the disc at a lower portion in the vertical direction of the cooling device, and an outer periphery of the guide immediately above the guide portion. Characterized in that it has an annular oil supply device having an annular slit for discharging an oil agent and a converging guide type oil supply device for converging the yarn downstream and supplying the second stage oil supply. Melt spinning apparatus of the ultra-fine fibers.
(10) The polyamide according to (9), wherein the cooling device is a cooling device that cools the melt-spun yarn by blowing cooling air from the inside of the melt-spun yarn discharged from the discharge hole. Ultra-fine fiber melt spinning equipment.

According to the present invention, as will be described below, in a polyamide fiber having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less, the average number of fluffs per 12000 m in the longitudinal direction of the filament is 1.0 or less. Excellent softness, smoothness, drape, high water absorption, high density, and high quality after dyeing can be obtained for woven and knitted fabrics, which cannot be obtained with polyamide ultrafine fibers. . In a more preferred embodiment, excellent anti-penetration properties can also be imparted.

FIG. 1 is a diagram showing an example of a method for producing polyamide ultrafine fibers according to the present invention. FIG. 2 is a diagram showing an example of the shape of a cap hole used for producing the polyamide ultrafine fiber of the present invention. FIG. 3 is a view showing another example of the shape of the cap hole used for producing the polyamide ultrafine fiber of the present invention. FIG. 4 is a diagram showing an example of an annular oil supply device preferably used when producing the polyamide ultrafine fiber of the present invention. FIG. 5 is a diagram showing another example of the method for producing polyamide ultrafine fibers according to the present invention.

Hereinafter, the actual form of the present invention will be described in detail.

The polyamide used in the polyamide ultrafine fiber of the present invention is a polyamide homopolymer or copolymer, and these polyamides are melt-molded having an amide bond formed from a lactam, an aminocarboxylic acid or a salt of a diamine and a dicarboxylic acid. It is a possible polymer.

As the polyamide, various polyamides can be used, and are not particularly limited, but polycaproamide (nylon 6) and polyhexamethylene adipamide (nylon 66) are preferable in terms of fiber forming ability and mechanical properties. As these polyamide copolymers such as nylon 6 and nylon 66, those copolymerized with other aminocaproic acid, lactam, etc. at a ratio of 20 mol% or less with respect to the total monomer units can be used.

In addition, the sulfuric acid relative viscosity of the polyamide used in the present invention is preferably 2.0 to 3.5, more preferably 2.4 to 3.0, and still more preferably 2.5 from the viewpoint of yarn production stability. ~ 2.7. The method for measuring the relative viscosity of sulfuric acid will be described later.

In the polymer of the present invention, the second and third components may be copolymerized or mixed in addition to the main components within the range not departing from the object of the present invention.

In particular, in addition to the object of the present invention, when it is desired to provide hygroscopicity, it is also possible to include polyvinyl pyrrolidone in the polyamide.

In addition, various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent whitening agents and the like are added to the polyamide used in the present invention as necessary. It may be mixed.

The method for producing the polyamide ultrafine fiber of the present invention is not particularly limited as long as the polyamide ultrafine fiber of the present invention is obtained. However, the polyamide is melted and discharged from the discharge holes arranged circumferentially on the outer periphery of the spinneret. After cooling, using a cooling device that cools the melt spun yarn uniformly and rapidly by blowing cooling air from the inside or outside of the melt spun yarn discharged from the discharge hole at the lower part of the center of the base, In addition, a method is preferably used in which an oil agent is applied to each single yarn by an annular oiling device at the lower part of the cooling device in the vertical direction, and then the yarn is converged by a converging guide type oiling device and the second stage of oiling is performed. It is done. After the second stage of refueling, a one-step method in which an interlace is applied as necessary and wound on a package is preferable from the viewpoint of obtaining a polyamide fiber with particularly small thick spots and fluff and cost. The cooling device is preferably an annular cooling device, more preferably an outer blown annular cooling device that blows cooling air from the inside to the outside of the spun yarn running on the circumference of the circle, from the outside of the spun yarn. An internal blowing type annular cooling device that blows cooling air to the inside is preferable. In particular, an outer blowing type annular cooling device is preferable.

A preferred example of the method for producing a polyamide fiber of the present invention will be specifically described with reference to FIGS. FIG. 1 and FIG. 5 are schematic views showing an example of a synthetic fiber manufacturing process according to the present invention, FIG. 1 is an example using an outer blown annular cooling device 3, and FIG. 5 is an inner blown annular cooling device. This is another example using 18. In the following description, the basic configuration of the manufacturing process of FIGS. 1 and 5 is the same, and description of common reference numerals is omitted.

In FIG. 1, after the melted polyamide is discharged from the die 1 and passed through the heat retaining zone 2 below the die, an outer-blow-type annular type cooling installed at the lower center of the die for the purpose of reducing fineness unevenness in the longitudinal direction. The apparatus 3 blows cooling air from the inside to the outside of the spun yarn, and rapidly cools and solidifies each single yarn at a uniform distance from the die surface. Further, an annular oil supply device having a disk-shaped guide portion in which a single yarn contacts with the outer peripheral portion of the disk before focusing the yarn, and an annular slit for discharging the oil agent formed along the outer periphery of the guide immediately above the guide portion. After the oil agent is applied to each single yarn by 4, it is preferable that the yarn is converged by the converging guide type oiling device 5 and the second-stage oiling is performed. After refueling, an interlace is applied by an interlace nozzle 6 as necessary, passes through a take-up roller 7 and a drawing roller 8, and is taken up by a winder (winding device) 9. In addition, 10 is a fiber filament, 11 is a fiber product package. In addition, although it may be stretched by two or more sets of rollers before being wound on the package, in this case, since the interlace provided by stretching may be unraveled, the stretching ratio is lowered, or You may give an interlace again after extending | stretching.

In the heat retaining zone 2 below the base, steam is ejected toward the surface of the base and the heat retaining zone 2 is filled with steam because the polymer around the discharge hole of the base and the oligomer contained in the polymer react with oxygen. It is preferably used since it has an effect of suppressing solidification and so-called base stain. At this time, the vapor jet pressure is preferably 0.1 to 0.5 kPa. If the jet pressure is too small, the oxygen concentration in the heat retention zone below the base becomes high, and the effect of suppressing the contamination of the base surface becomes small. If the ejection pressure is too high, the discharged yarn will sway, leading to worsening of Wooster spots.

When cooling the spun yarn arranged on the circumference of the circle, using an annular cooling device and blowing cooling air radially outwardly on the yarn is an oligomer component generated from the polyamide discharged from the base Further, it is preferably used because the steam that seals the base and the base does not stay in the spinning device and can be released to the outside.

In the manufacturing process of FIG. 1, the outer blown annular cooling device 3 is used, but the inner blown annular cooling device 18 shown in FIG. 5 is used instead of the outer blown annular cooling device 3. You can also. The inner-blow-type annular cooling device 18 is installed at the lower part of the center of the base so as to surround the spun yarn, and blows cooling air from the outer side to the inner side of the spun yarn, so that each single yarn is uniform from the base surface. Cool and solidify quickly at a short distance.

The cooling start point distance, that is, the distance (L) from the base surface to the upper end of the cooling air blowing part in the annular cooling device is preferably 10 to 70 mm, more preferably 10 to 60 mm, still more preferably 10 to 50 mm. is there. If the cooling start point distance is too short, the cooling air blown out from the annular cooling device hits the die surface, and the die surface temperature decreases, so that the discharge stability of the thermoplastic polymer deteriorates, and spun yarn and fluff increase. . Also, if the cooling start point distance is too long, the polyamide solidifies before uniform and rapid cooling with cooling air, so that the fiber fineness fluctuation (Worster spots) tends to increase, and when the fabric is made There is a tendency for the quality to decline.

The wind speed of the cooling air in the annular cooling device is preferably 15 to 60 m / min, more preferably 20 to 55 m / min, and further preferably 25 to 50 m / min. If the cooling air speed is too low, uniform and rapid cooling of the single yarn will be insufficient, and the tension of the cooling yarn will be reduced. Further, since the fluff and spun yarn breakage occur frequently by contacting the guide with insufficient cooling of the polymer, the quality of the fabric is inferior. When the cooling air speed is too high, tension is applied to each single yarn, causing the yarn to vibrate slightly, increasing Worcester spots, and increasing yarn breakage during spinning.

The temperature of the cooling air in the annular cooling device is preferably 5 to 50 ° C., more preferably 10 to 40 ° C., and further preferably 15 to 35 ° C. If the temperature of the cooling air is too low, the temperature of the heat retention zone below the base decreases and the temperature of the base surface decreases, so the strength of the yarn tends to decrease. If the temperature of the cooling air is too high, the yarn In addition to the fact that the uniform cooling of the yarn becomes difficult and the cooling of the yarn is liable to be insufficient, and Worcester spots increase, the yarn breakage during spinning tends to increase.

The vertical length of the cooling air blowing part in the annular cooling device is preferably 100 to 500 mm, more preferably 150 to 400 mm, still more preferably 200 to 350 mm. If the cooling air blowing length is too long, the tension applied to the single yarn will increase, causing spun yarn breakage, and if the cooling air blowing length is too short, the oil will be applied with insufficient cooling of the single yarn, reducing fluff. , And spun yarn breakage.

The single yarn that has passed through the annular cooling device can be processed by the annular oiling device. This annular oil supply device is arranged inside a spun yarn that runs on a circular circumference.

FIG. 4 is a conceptual diagram showing an example of an annular fueling device preferably used in the present invention. The annular oil supply device 4 includes an oil discharge slit 12 and a disk-shaped guide 13. The annular oil supply device 4 is arranged so that the fiber filament (single yarn) 14 that has passed through the annular cooling device contacts the disk-shaped guide 13. An annular oil discharge slit 12 is formed along the outer periphery of the disk-shaped guide 13 so that the oil is supplied directly above the contact point of the disk-shaped guide 13 with the yarn. The oil agent is supplied from the oil agent supply pipe 17 to the oil agent reservoir 15. The oil agent filled in the oil agent reservoir 15 is discharged from the oil agent discharge slit 12 and comes into contact with each single yarn of the discharge yarn at the contact point with the yarn in the disk-shaped guide 13, and the oil agent is applied to each single yarn. .

Contacting the single yarn that has passed through the annular cooling device with the disk-shaped guide prevents the single yarn blown by cooling air from shaking, promotes uniform cooling of the single yarn, and reduces Worcester spots. Therefore, it is preferably used. Further, before converging the yarn, the oil agent is discharged from an annular slit for discharging the oil agent formed along the outer periphery of the guide just above the contact point with the yarn in the disk-shaped guide described above. The method using the annular oil supply device applied to the yarn is because the yarn with high friction resistance before applying the oil agent comes into contact with the disk-shaped guide, or the single yarn not applied with the oil agent is rubbed together when the yarn is bundled. A single yarn that has the effect of suppressing the generation of fuzz and that is not provided with an oil agent by a converging guide type oiling device, and that is not provided with an oil agent in the spinning process. It is preferably used because generation of fluff due to rubbing and generation of dyeing spots at the time of dyeing are suppressed, and fibers having high-order processability are obtained. The position where the oil agent is applied by the annular oiling device is preferably 300 to 1000 mm below the base surface, more preferably 350 to 700 mm, and still more preferably 400 to 600 mm. If the oil supply position is too high, the oil agent is applied with insufficient cooling of the single yarn, which causes a decrease in filament strength and fluffing.If the oil supply position is too low, the single yarn discharged from the base surface Longer distance to converge makes yarn swinging more likely, leading to fluffing and worsening of Wooster's spots, and also increases the accompanying airflow effect of single yarn, increasing the running yarn tension. , Causing yarn breakage. Although the kind of oil agent provided with a cyclic | annular oil supply apparatus is not specifically limited, It is preferable that it is an emulsion type. In the case of an emulsion oil agent, an oil film is likely to be formed on the guide due to surface tension, and the oil agent can be applied uniformly along the circumferential direction of the disk-shaped guide.

The method of adopting the two-stage oil supply method in which the single yarn is converged by the converging guide type oil supply device 5 after the oil supply by the annular oil supply device 4 and the oil supply is further performed is the double-sided between the single yarns of the fibers and in the longitudinal direction. It can be preferably used because it can achieve the uniform oil agent application. In the annular oil supply device 4, although the oil agent is uniformly applied between the single yarns, it is difficult to obtain fibers uniformly oiled in the longitudinal direction, and the converged guide type oil supply device that enables the application of the uniform oil agent in the longitudinal direction is possible. By adopting a two-stage lubrication system of 5 and the annular lubrication device 4, it is possible to apply a uniform oil agent between the single yarns of the fibers and both sides in the longitudinal direction, and it is possible to obtain polyamide ultrafine fibers of good quality after dyeing .

Also, the focusing guide type oiling device used for the second stage oiling can use a normal oiling guide, and for example, an oiling guide as shown in the above-mentioned Patent Document 3 is preferably used.

The take-up speed of the yarn in the take-up roller 7 is preferably 3500 to 4500 m / min. If the take-up speed is too low, the orientation of the polyamide in the longitudinal direction becomes unstable, and dyeing spots in the longitudinal direction are likely to occur, and if the take-up speed is too high, the tension applied to the yarn increases. Or cause spun yarn breakage. Furthermore, the draw ratio at the drawing roller 8 is preferably 1.0 to 1.3. If the draw ratio is too high, the elongation of the resulting fiber becomes too low, and in addition, the single yarn breaks and fluff is likely to occur.

The polyamide ultrafine fiber of the present invention is required to have a single yarn fineness of 0.1 dtex or more and 0.5 dtex or less, preferably 0.25 to 0.45 dtex. When the single yarn fineness is too thick, the yarn has high rigidity, and when it is made into a woven or knitted fabric, it is possible to obtain a woven or knitted fabric excellent in desired softness, smoothness, drape, high water absorption and high density. When the single yarn fineness is too thin, single yarn breakage is likely to occur when making the fabric, and the fluff and smoothness of the fabric tend to be inferior. There is a tendency for the quality to deteriorate. The single yarn fineness is measured by the method described later.

The average number of fluffs per 12000 m in the longitudinal direction of the filament is required to be 1.0 or less for the polyamide ultrafine fiber of the present invention. When the average number of fluff is more than 1.0, warp fluff is generated during weaving and knitting, processing thread breakage during false twisting, and unraveling defects occur. It lacks sex and quality. The average number of fluffs per 12000 m in the longitudinal direction is preferably 0.5 or less, and more preferably 0. In order to reduce the number of fluffs, it is preferable to prevent single yarns having high frictional resistance before applying the oil agent, and a method of applying the oil agent before the yarns are bundled by the above-described annular oil supply guide is preferable. The average number of fluffs is measured by the method described later.

The fiber generally shows a variation in the fineness of the yarn in the longitudinal direction, and the thick portion of the yarn tends to be deeply dyed at the time of dyeing, and this appears particularly when the fineness of the single yarn is small. If the fine fibers are large, the levelness of the woven or knitted fabric is deteriorated and the appearance is deteriorated. Therefore, the Wooster spots (thick spots) are preferably 1.0% or less. If the Wooster spots are too high, smoothness and a difference in shade at the time of dyeing are greatly developed, and the quality as a product tends to be inferior. Wooster spots are preferably 0.9% or less. The method for reducing Wooster spots is not particularly limited, but a method in which the cooling air blowing device is brought close to the base surface and rapidly cooled, or a method in which cooling air is blown in an annular shape from the outer periphery and / or inner periphery is preferably used. It is done. More preferably, after cooling the single yarn uniformly by blowing cooling air in an annular shape from the inner periphery of the yarn, each single yarn is brought into contact with a disk-shaped guide to prevent the yarn from shaking. In the present invention, Wooster spots (thick spots) are measured by the method described later.

When the polyamide ultrafine fiber of the present invention includes a single yarn having a circular cross-sectional shape, it is preferable that the orientation parameter of the surface portion and the orientation parameter of the central portion of the single yarn are different. The difference in the orientation parameter between the surface portion and the central portion results in a difference in the refractive index of light passing through the central portion and the surface portion of the polyamide ultrafine fiber, and an anti-penetration effect can be obtained even with a circular cross section. Specifically, the ratio of the orientation parameter of the single yarn surface part to the orientation parameter of the single yarn central part is preferably 1.10 or more, more preferably 1.15 times or more and 2.00 times or less, further preferably 1.20 or more and 1.80 times or less. When the orientation parameter of the surface portion is in the above range with respect to the orientation parameter of the center portion of the single yarn, light passing through the cross-sectional direction of the single yarn is irregularly reflected, so that when the fabric is used, a see-through effect is obtained, and The strain in the fiber internal structure does not become too large, and sufficient filament strength can be maintained. The orientation parameter is measured by the method described later. The polyamide ultrafine fiber having such an orientation parameter is manufactured by selecting the above-mentioned preferable conditions so that the cooling air velocity (cooling air velocity) is not too small so as not to make the cooling start point distance too long. Obtainable.

The polyamide ultrafine fiber of the present invention has a very fine single yarn fineness and is a fiber in which the structure of the orientation parameter of the surface portion and the orientation parameter of the central portion is different by cooling the melt-spun yarn uniformly and rapidly. By adopting cooling conditions that allow more rapid and uniform cooling, the ratio of the orientation parameter of the single yarn surface portion to the orientation parameter of the single yarn central portion tends to increase.

Further, the elongation of the polyamide ultrafine fiber is preferably 40 to 70%. If the elongation becomes too low, the tensile resistance of the filament becomes high, and the number of actual twists twisted in the false twisting process decreases, so that it becomes difficult to give sufficient crimp to the obtained processed yarn. In yarn, yarn breakage and fluff are likely to occur, and high-order passability tends to be inferior. On the other hand, if the elongation is too high, the actual number of twists to be twisted becomes excessive, fluffing occurs in the obtained processed yarn, the strength tends to decrease, and the drawn yarn has a high residual elongation. There is a tendency that streaks are likely to appear in the woven or knitted fabric, and the quality tends to be inferior. The measurement of the said elongation shall be based on the below-mentioned method.

Further, when the obtained polyamide ultrafine fiber is stretched 15%, the stress is 1.0 to 2.0 gf / dtex (9.8 × 10 ⁻³ to 19.6 × 10 ⁻³ N / dtex). And more preferably 1.2 to 1.8 gf / dtex (11.8 × 10 ⁻³ to 17.6 × 10 ⁻³ N / dtex). If the stress at 15% elongation is too low, the tension at the time of false twisting becomes too low, and the processed yarn is likely to break or change in the working tension, so that the quality of the processed yarn is lowered and the yield is likely to deteriorate. On the other hand, if the stress at 15% elongation is too high, a large tension is concentrated on the interlace part when performing false twisting, and breakage of the single yarn occurs, and the process passability and the quality of the woven or knitted fabric tend to be lowered. The measurement of the stress when the 15% elongation is performed is based on the method described later.

The total fineness of the polyamide ultrafine fiber of the present invention is preferably 15 to 300 dtex, more preferably 15 to 200 dtex. If the total fineness is too small, the breaking strength of the fiber becomes small, the tear strength of the last fabric made into a fabric becomes small, and if the total fineness is too large, it becomes difficult for the dye to penetrate into the fiber at the time of dyeing. Dyeing spots are likely to occur, making it difficult to obtain a high-quality fabric. The total fineness is measured by the method described later.

The number of filaments of the polyamide ultrafine fiber of the present invention is preferably 30 or more, more preferably 30 to 500 filaments, and still more preferably 50 to 400 filaments. If the number of filaments is less than 30, it will be difficult to obtain the desired softness, drape, high water absorption, and high density, and if the number of filaments is too large, it will be difficult to uniformly interlace and release. Is easily deteriorated, and it is difficult to apply a uniform oil agent between filaments, and the occurrence of fluff due to single yarn breakage is likely to increase.

The cross-sectional shape of the polyamide ultrafine fiber of the present invention is not particularly limited, and examples thereof include a circular cross section and an irregular cross section. For example, a flat section, a lens-type section, a trilobal section, a six-leaf section, a so-called multi-lobe section, a deformed section having three to eight convex sections and the same number of concave sections, a hollow section, and other known modified sections But you can. As a preferred cross section, a circular cross section is excellent in terms of spinning stability, excellent softness and draping properties. Further, when the polyamide ultrafine fiber has a circular cross section and the center part and the surface part have the ratio of the preferred orientation parameters, the light passing through the cross-sectional direction of the single yarn is irregularly reflected due to the structural difference in orientation, A material having a global cross section or a hollow cross section is preferable in that light passing through the surface of the single yarn is diffusely reflected, and therefore, when a cloth is used, high anti-transparency due to irregular reflection of transmitted light is obtained. Furthermore, the trilobal cross section, multi-lobe cross section, and cross-sectional configurations in which multi-lobe cross sections and circular cross-section filaments are mixed, high voids are obtained between single yarns when made into fabrics, resulting in high water absorption due to capillary action. In addition, it is excellent in that it can be imparted with high bulk density, and is also preferably used because it is excellent in imparting the anti-permeability due to irregular reflection of transmitted light.

The polyamide ultrafine fiber of the present invention thus obtained can give the fabric excellent softness, smoothness, drape, high water absorption, high density, and high quality after dyeing, and in a preferred embodiment it is further opaque. Excellent in properties. Therefore, when using the ultrafine fiber of the present invention as a woven fabric, it is used as an outer material such as a down jacket fabric excellent in heat retention and light weight, and when used as a knitted fabric, it is used for a high-class inner with the above functions, and tights. It can be preferably used for a covering yarn or the like.

Hereinafter, the present invention will be described in detail by way of examples.

Each characteristic value in the present specification and examples was determined according to the following method.

(1) Total fineness and single yarn fineness Using a measuring machine with a frame circumference of 1.000 m, create a 1000-turn casserole for varieties below 27 decitex and a 500-turn casserole for varieties above 28 decitex Then, after drying at 105 ± 2 ° C. for 60 minutes with a hot air dryer, the value calculated by the following formula (i) or (ii) based on the value measured with a balance was taken as the total fineness. Further, the value obtained by dividing the obtained total fineness by the number of single yarns was defined as the single yarn fineness.
(I) Varieties of 27 dtex or less Total fineness (dtex) = Weighed value (g) × (10000/1000) × {1+ (official moisture content (%) / 100)}
(Ii) Varieties of 28 dtex or more Total fineness (dtex) = Weighed value (g) × (10000/500) × {1+ (official moisture content (%) / 100)}
Here, for the nylon 6 and nylon 66 polymers used in the examples, the fineness was calculated with an official moisture content of 4.5%.
Single yarn fineness (dtex) = total fineness (dtex) / number of single yarns However, for the single yarn fineness in the mixed filaments of two different types of cross-sectional shapes (cross-section A and cross-section B), The area ratio of the cross section of the single yarn in the cross-sectional shape was calculated, and the value obtained by multiplying the total fineness by the area ratio and dividing by the total number of filaments of the same shape.
Area ratio of section A = area of section A / (area of section A + area of section B)
Area ratio of section B = area of section B / (area of section A + area of section B)
Single yarn fineness (dtex) of cross section A in mixed filaments = (total fineness (dtex) × area ratio of cross section A) / number of filaments of cross section A Single yarn fineness (dtex) of cross section B in mixed filaments = ( Total fineness (dtex) × area ratio of section B) / number of filaments in section B

(2) Sulfuric acid relative viscosity A sample is weighed and dissolved in 98% by weight concentrated sulfuric acid so that the sample concentration (C) is 1 g / 100 ml, and the solution is dropped by an Ostwald viscometer at 25 ° C. (T1 ). Furthermore, about 98 weight% concentrated sulfuric acid which has not melt | dissolved the sample, after similarly dropping seconds (T2) at 25 degreeC are measured, the relative viscosity ((eta) r) of a sample is computed by the following Formula.
(Ηr) = (T1 / T2) + {1.891 × (1.000−C)}

(3) Average number of fluff The average number of fluff is set using the MALUTI-POINT FRAY COUNTER MFC-200 (sensor part F type) from Toray Engineering Co., Ltd. (current name is tmt machinery) (sensor optical axis center) To U-Guide bottom): 2.0 mm, yarn speed: 600 m / min, measurement time: 20 minutes, feed tension: within the range of 0.25 g / dtex to 0.75 g / dtex The number of measurements was measured 10 times, and the measurement average value was defined as the average number of fluffs (pieces / 12,000 m).

(4) Orientation parameter ratio Orientation parameters were measured by Raman spectroscopy for a sample (single yarn) having a circular cross-sectional shape, using T-64000 manufactured by Jobin Yvon / Ehime Bussan Co., Ltd., measurement mode: microscopic Raman, objective Lens: × 100, beam diameter: 1 μm, light source: Ar ⁺ laser / 514.5 nm, laser power: 100 mW, diffraction grating: Single 600, 1800 gr / mm, slit: 100 μm, detector: CCD 1024 × 256 manufactured by Jobin Yvon The measurement was performed under the following conditions. A measurement sample was embedded in a resin (bisphenol-based epoxy resin, cured for 24 hours) and then sectioned with a microtome at a cutting angle of 5 ° or less from the fiber longitudinal direction. The slice sample had a thickness of 1.5 μm and was cut out so as to pass through the center of the fiber. The measurement of the orientation is performed under polarization conditions. When the polarization direction coincides with the longitudinal direction of the fiber, the parallel polarization (∥) and when perpendicular, the vertical polarization (⊥) are obtained, and in the obtained Raman band, the vicinity of 1130 cm ⁻¹ is obtained. The degree of orientation was evaluated from the ratio of the peak intensity (I ₁₁₃₀ ) attributed to the CC deformation vibration mode and the peak intensity (I ₁₆₃₅ ) attributed to C = C stretching vibration near 1635 cm ⁻¹ . That is, orientation parameter = (I ₁₁₃₀ / I ₁₆₃₅ ) ∥ / (I ₁₁₃₀ / I ₁₆₃₅ ) ⊥
It is. Among the measurement points, the orientation parameter of the single yarn surface portion was irradiated with a laser at a point 1 μm inside from the single yarn surface portion, and the central orientation parameter was calculated at the center portion of the single yarn to calculate the orientation parameter. From this result, the ratio of the orientation parameter of the single yarn surface part to the orientation parameter of the single yarn central part was calculated by the following formula. In addition, about the orientation parameter of the single yarn center part and the single yarn surface part, it calculated using the average value in five single yarns collected at random from the filament.
Orientation parameter ratio = (Orientation parameter of single yarn surface portion) / (Orientation parameter of single yarn central portion)

(5) Wooster plaques Wooster plaques were measured using a ZELLWEGER USTER USTER TESTER UT-4, measuring at a yarn speed of 50 m / min, S twist, and a twist number of 8000 rpm for 3 min. Was measured.

(6) 15% elongation stress 15% elongation stress when using TENSIRON RPC-1210A manufactured by ORIENTEC, gripping at a gripping interval of 50 cm, stretching at a pulling speed of 50 cm / min, and stretching to 57.5 cm The tension was measured three times, and the average value was divided by the fineness of the fiber.

(7) Elongation The elongation is measured using a TENSIRON RPC-1210A manufactured by ORIENTEC, gripped at a gripping interval of 50 cm, stretched at a pulling speed of 50 cm / min, and the tensile length when the yarn breaks is measured three times. The average value was divided by 50 cm and multiplied by 100.

(8) Softness of cloth The softness, the smoothness of the surface, the drapeability, and the color depth of the cloth were determined visually and tactilely, and the following four stages were determined.
(A)... Very good (the dyed fabric is soft, the surface is smooth and draped. No fuzz is observed on the fabric surface)
(B) ... good (although it is excellent in softness and drapeability, it is inferior in smoothness, and some surfaces are fluffy.)
(C) ··· Slightly poor (although it has drape properties, it is inferior in softness and smoothness, and some fluff is seen.)
(D) Defective (the fabric is hard, smooth and drape is inferior, and the surface is fuzzy).

(9) Dyeing quality of the fabric The obtained fiber was used for both vertical and horizontal, and a plain woven fabric having a length of 180 cm was created, and the fabric was dyed with an acid dye (Mitsui Nylon Black GL). The plain fabric after dyeing was inspected 100 m in the longitudinal direction by an inspector (10 persons) using a fluoroscopic inspection machine, and subjected to relative evaluation according to the following criteria.
(A) ... there are no streaks or shading.
(B) ... Slight streaks and uneven shading are seen, but at a practical level.
(C) ···················································· Practical level
(D) A lot of strong streaks and shading unevenness is observed, which is not at a practical level.

(10) Water absorbency of fabric (Bilec method)
Measured according to JIS L1096 (1999) “Bilec method”. The water absorption height obtained by this measurement was evaluated according to the following criteria.
(A) ... 90 mm or more (B) ... 65 mm or more and less than 90 mm (C) ... 55 mm or more and less than 65 mm (D) ... less than 55 mm.

(11) The sheerness of the fabric After the tube was knitted with the obtained fiber, the sheerness of the fabric after scouring was relatively evaluated according to the following criteria by the evaluation of an inspector (10 persons).
(A) ... very good (no sense of sheer, can be used as a sheer-proof material)
(B) ... good (a slight sense of sheerness is recognized, but a practical level as a sheerproof material)
(C): Practical (level that is not a problem in normal use)
(D) ・・・ Bad (Transparency is strong and cannot be used for inner)

(12) Comprehensive evaluation of fabrics The following criteria were evaluated as comprehensive evaluations of fabrics.
(A)... (A) or (B) evaluation for all four items of fabric softness, dyeing quality, water absorption, and see-through property, and two or more items are (A).
(B) ... In four items of fabric softness, dyeing quality, water absorption, and see-through property, (C) evaluation is 1 item or less, but there is no (D) evaluation item.
(C)... There are no (D) evaluation items for all four items of fabric softness, dyeing quality, water absorption, and anti-peeling properties, but (C) there are two or more evaluation items.
(D): One or more items among the four items of fabric softness, dyeing quality, water absorption, and see-through property include (D) evaluation items.

Example 1
Nylon 66 with a 98% sulfuric acid relative viscosity of 2.63 is melted at 285 ° C., then supplied to a melt spinneret pack, and discharged from a die hole having a 98-hole circular hole. Each single yarn is directed to the spinneret surface. After passing through a steam ejection zone where steam is ejected at a pressure of 0.25 kPa, a cooling air blowing section having a cooling start point distance of 30 mm and a vertical length of 300 mm is provided downstream of the steam ejection zone. A single outer-blow-type annular cooling device is passed through, and 20 ° C. cooling air blown radially is blown to the outer blow at a wind speed of 40 m / min to cause cooling and solidification. Thereafter, at a position 500 mm from the base surface, an annular oil supply having a disk-shaped guide part in contact with the single yarn at the outer peripheral part of the disk and an annular slit for discharging the oil agent formed along the outer periphery of the guide immediately above the guide part. Emulsion oil agent is applied by the device, and further, the second stage of oil is supplied by the convergence guide type oil supply device, the yarn is converged, and the interlace is applied, and it is taken up at 4000 m / min, and the draw ratio is 1.10 times. Then, the film was wound at 4200 m / min under relaxing conditions to obtain a nylon 66 fiber having 40 dtex / 98 filament and 45% elongation. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1. In the table, nylon 66 is abbreviated as N66.

Example 2
Nylon 6 having a 98% sulfuric acid relative viscosity of 2.63 was melted at 255 ° C. and then spun in the same manner as in Example 1 except that it was used in a melt spinneret pack to obtain a nylon 6 fiber of 40 dtex / 98 filament. It was. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1. In the table, nylon 6 is abbreviated as N6.

Example 3
Spinning was carried out in the same manner as in Example 1 except that a die having a 268 hole circular hole was used, and a nylon 66 fiber of 40 dtex / 268 filament was obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1.

Example 4
Spinning was carried out in the same manner as in Example 1 except that a base having a circular hole of 82 holes was used to obtain a nylon 66 fiber of 40 dtex / 82 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1.

Example 5
Example 1 except that the length in the vertical direction of the cooling air blowing portion in the outer-blow-type annular cooling device installed downstream of the steam blow zone below the mouthpiece is 100 mm, and the fueling position by the annular fueling device is 300 mm below the mouthpiece. Spinning was carried out in the same manner as described above to obtain 40 dtex / 98 filament nylon 66 fibers. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1.

Example 6
Spinning was carried out in the same manner as in Example 1 except that nylon 66 having a 98% sulfuric acid relative viscosity of 2.63 was melted at 275 ° C. to obtain a nylon 66 fiber of 40 dtex / 98 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 1.

Example 7
Spinning was performed in the same manner as in Example 1 except that a die having a 42 hole circular hole was used and the fineness was changed to 17 dtex to obtain a nylon 66 fiber of 17 dtex / 42 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 2.

Example 8
Spinning was performed in the same manner as in Example 1 except that a die having a circular hole of 680 holes was used and the fineness was changed to 280 dtex to obtain nylon 66 fibers of 280 dtex / 680 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 2.

Example 9
Spinning was carried out in the same manner as in Example 1 except that a die having a 32-hole circular hole was used and the fineness was changed to 15 dtex to obtain nylon 66 fibers of 15 dtex / 32 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 2.

Example 10
Nylon 6 with a 98% sulfuric acid relative viscosity of 2.63 is melted at 255 ° C. and then supplied to a melt spinning die pack, and discharged from a die outlet hole having a three-leaf slit shape as shown in FIG. Except for the above, spinning was carried out in the same manner as in Example 1 to obtain a three-leaf section nylon 6 fiber having 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 2.

Example 11
Spinning was carried out in the same manner as in Example 10 except that a 49-hole die discharge hole having a cross-sectional shape of 49 holes as shown in FIG. 3 and a 98-hole die mixed with the same number of round holes were used, A nylon 6 fiber in which a 6-leaf section and a round section of 40 dtex / 98 filament were mixed was obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 2.

Example 12
After applying interlace, it was taken out at 3000 m / min, drawn at a draw ratio of 1.50, and then wound up at 4300 m / min under relaxed conditions in the same manner as in Example 1. Spinning was performed to obtain nylon 66 fibers of 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 3.

Example 13
Spinning was carried out in the same manner as in Example 1 except that a single inner-blow-type annular cooling device having a cooling air blowing portion having a vertical length of 300 mm was passed instead of the outer-blow-type annular cooling device. , 40 dtex / 98 filament nylon 66 fiber was obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 3.

Example 14
Spinning was carried out in the same manner as in Example 1 except that the cooling start point distance was 20 mm to obtain 40 dtex / 98 filament nylon 66 fibers. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 3.

Example 15
Spinning was carried out in the same manner as in Example 1 except that the cooling start point distance was 40 mm, to obtain nylon 66 fibers of 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 3.

Example 16
Spinning was performed in the same manner as in Example 1 except that the cooling start point distance was set to 10 mm, to obtain nylon 66 fibers of 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 3.

Example 17
Spinning was carried out in the same manner as in Example 1 except that the cooling start point distance was 60 mm to obtain 40 dtex / 98 filament nylon 66 fibers. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 4.

Example 18
Spinning was carried out in the same manner as in Example 1 except that the air velocity of the cooling air at 20 ° C. blown radially from the outer blown annular cooling device to 27 m / min, and nylon 66 fiber of 40 dtex / 98 filament was obtained. Obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 4.

Example 19
Spinning was carried out in the same manner as in Example 1 except that the air velocity of the cooling air at 20 ° C. blown radially from the outer blown annular cooling device to 49 m / min, and nylon 66 fibers of 40 dtex / 98 filaments were obtained. Obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 4.

Example 20
Spinning was performed in the same manner as in Example 1 except that the air speed of the cooling air at 20 ° C. blown radially outward from the outer blown annular cooling device was changed to 17 m / min, and nylon 66 fiber of 40 dtex / 98 filament was obtained. Obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 4.

Example 21
Spinning was carried out in the same manner as in Example 1 except that the air velocity of the cooling air at 20 ° C. blown radially outward from the outer blown annular cooling device was set to 58 m / min, and nylon 66 fiber of 40 dtex / 98 filament was obtained. Obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 4.

Comparative Example 1
Spinning was carried out in the same manner as in Example 1 except that the material was discharged from a die hole having a 160-hole circular hole and the fineness was set to 15 dtex to obtain nylon 66 fiber of 15 dtex / 160 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

Comparative Example 2
Spinning was carried out in the same manner as in Example 1 except that the fineness was 56 dtex to obtain nylon 66 fiber of 56 dtex / 98 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

Comparative Example 3
At a position 500 mm from the base surface of the lower part in the vertical direction of the outer blow type annular cooling device, a disk-shaped guide having no annular slit for discharging the oil is used, and the single thread is brought into contact with the disk-shaped guide without supplying the oil. Except for the above, spinning was performed in the same manner as in Example 1 to obtain a nylon 66 fiber of 40 dtex / 98 filament. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

Comparative Example 4
Spinning was performed in the same manner as in Example 1 except that the polyethylene terephthalate resin was melted at 290 ° C. and then used in a melt spinneret pack to obtain polyethylene terephthalate fibers of 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

Comparative Example 5
Spinning was performed in the same manner as in Example 1 except that the cooling device was a one-way type uniflow chimney, the yarn was converged by an oil supply guide, and oil was supplied to obtain nylon 66 fibers of 40 dtex / 98 filaments. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

Comparative Example 6
Spinning is carried out in the same manner as in Example 1 except that the second stage oiling is performed and the yarn is converged by the converging guide after the second lubrication, and the nylon 66 of 40 dtex / 98 filament is used. Fiber was obtained. The properties of the obtained raw yarn and fabric were evaluated. The results are shown in Table 5.

DESCRIPTION OF SYMBOLS 1 Base 2 Heat retention zone under base 3 Outer blow type annular cooling device 4 Annular lubrication device 5 Converging guide type lubrication device 6 Interlace nozzle 7 Take-out roller 8 Stretch roller 9 Winder (winding device)
DESCRIPTION OF SYMBOLS 10 Fiber filament 11 Textile product package 12 Oil agent discharge slit 13 Disc-shaped guide 14 Fiber filament 15 Oil agent reservoir 16 Oil agent 17 discharged from slit 17 Oil supply pipe 18 Inner blown annular cooling device

Claims

Polyamide ultrafine fiber characterized in that, in a polyamide fiber having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less, the average number of fluffs per 12000 m in the longitudinal direction of the filament is 1.0 or less.
2. The polyamide ultrafine fiber according to claim 1, wherein a Wooster spot in the longitudinal direction of the filament is 1.0% or less.
The polyamide ultrafine fiber according to claim 1 or 2, wherein the total fineness is 15 to 300 dtex and the number of filaments is 30 or more.
The polyamide ultrafine fiber according to any one of claims 1 to 3, wherein the filament has an irregular cross-section.
In the polyamide ultrafine fiber, the filament has a single yarn with a circular cross-sectional shape, and the orientation parameter of the single yarn having a circular cross-sectional shape has a ratio of the orientation parameter of the single yarn surface portion to the orientation parameter of the single yarn central portion. The polyamide ultrafine fiber according to any one of claims 1 to 3, which is 1.10 or more.
A melt spinning method for polyamide ultrafine fibers having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and an average number of fluffs per 12000 m in the longitudinal direction of the filament of 1.0 or less. A melt-spun yarn spun from a spinneret having discharge holes arranged in a circumferential shape is cooled from the inside or outside of the melt-spun yarn discharged from the discharge hole at the bottom of the center of the spinneret. Cool by using a cooling device that cools the melt-spun yarn by blowing air, and further, a disk-shaped guide part in which the single yarn contacts the lower part in the vertical direction of the cooling device at the outer periphery of the disk, and immediately above the guide part. After supplying oil by using an annular oil supply device having an annular slit for discharging an oil agent formed along the outer periphery of the guide, the yarn is converged by the converging guide type oil supply device and the second stage of oil supply is performed. Melt spinning method of the polyamide ultrafine fiber characterized and.
The melt of polyamide ultrafine fiber according to claim 6, wherein the cooling device is a cooling device that cools the melt spun yarn by blowing cooling air from the inside of the melt spun yarn discharged from the discharge holes. Spinning method.
The method for melt spinning polyamide ultrafine fibers according to claim 6 or 7, wherein the cooling device satisfies the following conditions.
(1) The distance (L) from the spinneret surface to the cooling start position of the cooling device is 10 mm ≦ L ≦ 70 mm
(2) The speed of the cooling air blown out at the cooling start position is 15 to 60 m / min.
A melt spinning apparatus for polyamide ultrafine fibers having a single yarn fineness of 0.10 dtex or more and 0.50 dtex or less and an average number of fluffs per 12000 m in the longitudinal direction of the filament of 1.0 or less. A spinneret having discharge holes arranged in a circumferential shape and a melt-spun yarn by blowing cooling air from the inside or outside of the melt-spun yarn discharged from the discharge hole at the lower part of the center of the spinneret. A disk-shaped guide portion that contacts a single yarn at the outer peripheral portion of the disk at the lower portion in the vertical direction of the cooling device, and formed along the outer periphery of the guide directly above the guide portion. A polyamide electrode having an annular oil supply device having an annular slit for discharging an oil agent, and a converging guide type oil supply device for converging the yarn downstream and supplying the second stage of oil supply Melt spinning apparatus of the fiber.
The melting device for polyamide ultrafine fibers according to claim 9, wherein the cooling device is a cooling device for cooling the melt spun yarn by blowing cooling air from the inside of the melt spun yarn discharged from the discharge holes. Spinning device.