JP2007009368A - Spinneret and method for producing ultrafine fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinneret capable of stably producing an ultrafine fiber. <P>SOLUTION: The spinneret has the following characteristics. (1) The outside diameter of the spinneret is 75-125 mm. (2) Polymer-introducing holes are arranged in 2-6 lines in a circumferential state. (3) The relationship between D2 (mm) defined as two time of maximum value of a line (radius) binding the center of the spinneret and the center of the polymer-introducing hole and the outside diameter D1 (mm) satisfies the formula: 0.6×D1≤D2≤0.85×D1. (4) The relationship between line interval L (mm) of the polymer-introducing holes and an introducing hole diameter D3 (mm) satisfies the formula: 1.3×D3≤L≤6×D3. (5) The numbers of discharge holes per polymer-introducing hole are 2-8. (6) The ratio D4/D3 of D4 (mm) defined as two times of maximum value of a line (radius) binding the center of the polymer-introducing hole and the center of the discharge hole to the diameter D3(mm) of the polymer-introducing hole is 0.5-0.9. (7) Total numbers of discharge holes are 120-600. (8) Discharge holes in one group are not arranged in a radial direction of the spinneret. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a die suitable for producing ultrafine fibers having superior quality than conventional ones and a method for producing synthetic fibers using the same.

  Extra fine fibers are widely used in clothing applications due to their thinness and softness, and in recent years, they are also being used in industrial material applications such as vehicle interior materials such as car seats.

  Among them, polyester microfibers typified by polyethylene terephthalate are fibers having high strength, high Young's modulus, and excellent thermal dimensional stability, and demand is particularly high among the above applications.

  However, it is also a fact that the problems of productivity and quality remain for the ultrafine fibers because of the difficulty of the production process.

  In general, in polyester, polyamide, etc. produced by melt spinning, in order to obtain ultrafine fibers, it is necessary to discharge a large number of yarns from a spinneret of a certain area, so the number of filaments is limited. It was. Also, in the process of cooling with a cooling air after discharging a large number of filaments, the cooling air is difficult to pass due to the large number of filaments, and uniform cooling is difficult. There is a problem that the quality of the used fabric is lowered.

  In order to solve such a problem, the yarn discharged from the spinneret is cooled and solidified by blowing cooling air from a direction perpendicular to the yarn, and then passed through an annular protective cylinder to prevent disturbance, thereby preventing Wooster spots. A reduction method has been proposed (see, for example, Patent Document 1). However, this method does not consider the portion where the yarn is cooled, and therefore the improvement of Wooster spots is insufficient.

  In addition, a method has been proposed in which a partition plate is provided between the spinneret and the cooling area by the cooling air to reduce Wooster spots by stabilizing the flow of the cooling air under the base while suppressing the cooling of the base. (For example, refer to Patent Document 2). However, even with this method, the yarn sway is induced by the turbulent flow of the cooling air in the portion where the partition plate and the yarn are close to each other, so that the improvement of the Wooster spot remains insufficient.

On the other hand, there has also been proposed a method for improving Wooster spots and thread breakage by preventing abnormal stagnation in the polymer pack and in the mouthpiece (see, for example, Patent Document 3). However, although this method mentions cleaning of the polymer by reducing abnormal stagnation, it does not consider the cooling of the yarn after discharge, and the fact that the Wooster spots are not improved by uniform cooling is the actual situation. It is.
Japanese Patent Laid-Open No. 62-243824 (first page) JP 09-137317 A (second page) Japanese Patent Application Laid-Open No. 07-300716 (second page)

  An object of the present invention is to provide a spinneret capable of stably producing ultrafine fibers having Wooster spots superior to conventional ones with high productivity and a method for producing ultrafine fibers using the same.

In order to achieve the above object, the present invention adopts the following configuration. That is,
[1] The following (1) to (8)
(1) having a circular base having an outer diameter D1 of 75 to 125 mm,
(2) In the base, 2 to 6 rows of polymer introduction holes are arranged circumferentially,
(3) The relationship between D2 (mm) defined by twice the maximum value and the outer diameter D1 (mm) of the die, with the line connecting the center of the die and the center of the polymer introduction hole as the radius,
0.6 × D1 ≦ D2 ≦ 0.85 × D1
Satisfied,
(4) The relationship between the row interval L (mm) of the polymer introduction holes and the introduction hole diameter D3 (mm)
1.3 × D3 ≦ L ≦ 6 × D3
Satisfied,
(5) 2 to 8 discharge holes are drilled with respect to the one polymer introduction hole,
(6) D4 defined by twice the maximum value with the discharge hole perforated in the one polymer introduction hole as one group, and a line connecting the center of the polymer introduction hole and the center of the discharge hole as a radius (Mm) and the ratio of the polymer introduction hole diameter D3 (mm),
D4 / D3 = 0.5-0.9
Satisfied,
(7) Furthermore, the total number of ejection holes is 120 to 600 holes,
(8) The discharge holes in one group are arranged so as not to be aligned in the radial direction with respect to the center of the die.
A spinneret characterized by having the following requirements.

[2] The spinneret according to [1] above, wherein the discharge holes in one group are concentrically drilled. [3] A separation band for two ridges is provided. The spinneret according to [1] or [2].

  [4] The spinneret according to [3], wherein the separation band width W (mm) is 12 to 24.

  [5] A method for producing an ultrafine fiber, characterized in that the base according to any one of claims 1 to 4 is used for spinning using an annular cooling device.

  [6] The method for producing ultrafine fibers according to [5], wherein the synthetic fiber is an ultrafine fiber having a filament number of 60 to 600 and a single yarn fineness of 0.2 to 1.0 dtex.

  According to the spinneret of the present invention, Worcester spots are improved, yarn breakage during production is reduced, and it becomes possible to produce ultrafine fibers stably with high productivity.

  As shown in FIG. 1, the spinneret of the present invention is a circular die and has an outer diameter D1 of 75 to 125 mm. If it is not circular, handling of the pack on which the base is mounted becomes complicated and is not suitable for annular cooling. Further, when the outer diameter D1 is less than 75 mm, the number of discharge holes that can be perforated in the die is limited, so that the number of multifilaments required at the same time when producing ultrafine fibers is insufficient. In addition, when the outer diameter D1 exceeds 125 mm, a large number of discharge holes can be drilled without satisfying the requirements described below, so the effect of the present invention is reduced.

  In the spinneret of the present invention, the introduction holes are circumferentially arranged in 2 to 6 rows. In the case of not having a circumferential shape, the uniformity of the ultrafine fibers obtained by uniform cooling by annular cooling after discharge is impaired. Further, when the number of rows is 7 or more, the cooling air is less likely to pass between the yarns in the process of cooling with the cooling air after the polymer is discharged from the discharge holes even though the rows are arranged in an annular shape. The target uniform cooling effect is impaired.

  The spinneret of the present invention has a line connecting the center of the base and the center of the polymer introduction hole as a radius, and D2 (mm) defined by twice the maximum value is 0.6 × the outer diameter of the base D1 (mm) The above is 0.85 × the outer diameter of the base D1 (mm). When D2 is smaller than 0.6 × D1, the cooling air is less likely to pass between the yarns in the step of cooling with cooling air after the polymer is discharged from the discharge holes, so that the intended uniform cooling effect is impaired. . Further, when D2 is larger than 0.85 × D1, when the yarn sways, contact with the annular cooling device or the like may occur, and yarn breakage may occur.

  Further, the spinneret of the present invention is such that 1.3 × D3 ≦ L ≦ 6 × D3, where L (mm) is the interval between the polymer introduction holes and D3 (mm) is the introduction hole diameter. In the case where L is smaller than 1.3 × D3, the interval between the two yarn groups discharged from the two introduction holes is too small, and therefore the polymer is discharged from the discharge holes and then cooled by cooling air. This makes it difficult for the cooling air to pass through and impairs the intended uniform cooling effect. On the other hand, when L is larger than 6 × D3, the row interval is too large, so that a large number of discharge holes cannot be punched, and the desired multifilament yarn cannot be obtained.

  Further, the spinneret of the present invention has 2 to 8 discharge holes per one introduction hole. When the number of discharge holes for one introduction hole is one, the number of filaments required at the same time when producing ultrafine fibers is insufficient. In the case of 9 holes or more, since the interval between the filaments discharged from one introduction hole is too small, the cooling air becomes difficult to pass in the process of cooling with the cooling air after discharging the polymer from the discharging hole, and the desired uniform The effect of cooling is impaired.

  Further, in the spinneret of the present invention, when the discharge holes perforated with respect to one introduction hole are made into one group and the PCD of the discharge hole group is set to D4 (mm), the diameter of the polymer introduction hole is D3 (mm). On the other hand, D4 / D3 is set to 0.5 to 0.9 (see FIG. 3).

  As shown in FIG. 3, the PCD of the discharge hole group is defined as a radius that is a line connecting the center of the polymer introduction hole and the center of the discharge hole, which is twice the maximum value. That is, it refers to the diameter of a circle centered on the center of the polymer introduction hole that passes through the center of the discharge hole farthest from the center of the polymer introduction hole.

  When D4 / D3 is less than 0.5, the interval between the filaments is too small, so in the process of cooling with cooling air after discharging the polymer from the discharge holes, it becomes difficult for the cooling air to pass between the yarns. The effect of uniform cooling is impaired. In addition, there may be a concern about abnormal retention of the polymer at the bottom of the introduction hole. On the other hand, if it exceeds 0.9, it is difficult to process the discharge holes.

  Further, the shape of the bottom portion of the introduction hole is not particularly limited, but the bottom portion is preferably horizontal from the viewpoint of ease of drilling and cost.

  The spinneret of the present invention has a total number of ejection holes of 120 to 600 holes. When the number is less than 120 holes, the multifilament formation required at the same time when producing ultrafine fibers becomes insufficient. In the case of more than 600, in the process of cooling with cooling air, it becomes difficult for the cooling air to pass through and the intended effect of uniform cooling is impaired.

  The spinneret of the present invention is arranged so that the discharge holes in one group are not aligned in the radial direction. When the discharge holes in one group are arranged in the radial direction, in the annular cooling that is blown from the radial direction, the cooling of the inner yarn is hindered by the outer yarn, so that the intended uniform cooling effect is impaired. In the discharge holes in one group, the angle θ formed by the lines connecting the discharge holes and the center of the die is preferably 0.3 ° or more and 5 ° or less, and more preferably 0.6 ° or more. . When the angle is less than 0.3 °, the cooling air becomes difficult to pass in the step of cooling with the cooling air, and the intended uniform cooling effect is impaired. On the other hand, when the angle is larger than 5 °, the number of multifilaments required at the same time when producing ultrafine fibers is insufficient.

  In the spinneret of the present invention, it is preferable that the discharge holes formed in one introduction hole are formed concentrically. As a result, the thermal histories of the filaments discharged from one introduction hole through the discharge hole become substantially equal, so that the uniformity of the obtained ultrafine fibers is improved.

  The spinneret of the present invention may have two piles in order to efficiently obtain the objective ultrafine fiber with more multifilaments. At this time, a separation zone between the mountains for the purpose of forming two mountains may be provided. The width W of the separation band is preferably 12 to 24 mm. If the width W of the separation band is less than 12 mm, it is difficult to separate the two obtained yarn groups because the distance between the mountains is small, or the filaments of one yarn group are mixed into the other yarn group. This is not preferable because there may be a problem such as. On the other hand, when the size is larger than 24 mm, the above-mentioned problem is solved, but the number of holes that can be perforated is limited, so that the number of multifilaments required at the same time when producing ultrafine fibers becomes insufficient.

  When producing the ultrafine fiber using the spinneret of the present invention, the thermoplastic polymer may be melted and discharged from the spinneret, taken up and then wound up, and then drawn or drawn false twisted, or wound without being drawn. You may take it.

  Specific examples of the thermoplastic polymer used for the production of the ultrafine fiber using the spinneret of the present invention include polyester, polyamide, and polyethylene.

  Of these, polyesters are polymers synthesized from dicarboxylic acids or their ester-forming derivatives and diols or their ester-forming derivatives, and those that can be used as molded articles such as fibers, films and bottles are preferred.

  Specific examples of such polyester include polyethylene terephthalate, polypropylene terephthalate, polytetramethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, polyethylene-1,2-bis (2-chlorophenoxy) ethane. 4,4′-dicarboxylate and the like. The present invention is suitable for polyethylene terephthalate or polyester copolymers mainly containing ethylene terephthalate units, which are most commonly used.

  These polyesters may be copolymerized with various ester-forming derivatives as long as the objects and effects of the present invention are not impaired.

  In addition, these polyesters include a matting agent such as titanium dioxide, various functional particles such as silicon oxide and kaolin, as well as an anti-coloring agent, a stabilizer, and an antioxidant as long as the objects and effects of the present invention are not impaired. You may contain additives, such as an agent.

  Next, the manufacturing method of the ultrafine fiber of this invention is demonstrated. Although the example of the ultrafine fiber using a polyethylene terephthalate is described as a specific example, it is not limited to this.

  Polyester fibers are usually (1) a process in which the polyester is melted, weighed, filtered, and discharged, (2) a process in which the discharged polyester filament is cooled by cooling air, and then (3) It is obtained by a winding process and (4) a process of stretching or stretching false twisting of the polyester fiber obtained in some cases.

  When ultrafine fibers are obtained using the spinneret of the present invention, (1) of the above processes is performed by a conventional method. As for (2), since the spinneret of the present invention allows the cooling air to pass through, the cooling air may be blown from one direction, but an annular cooling device is used and the cooling air is drawn from the entire circumferential direction surrounding the yarn. A method of spraying toward the center is preferable. The following processes (3) and (4) may be performed according to a conventional method.

  When ultrafine fibers are obtained using the spinneret of the present invention, the ultrafine fibers preferably have 60 or more filaments and a single yarn fineness of 1.0 dtex or less. When the number of filaments is less than 60 or the single yarn fineness is greater than 1.0 dtex, the Worcester spots of the ultrafine fibers are not bad even in the usual method, and therefore the effect of improving the Wooster spots by the spinneret of the present invention is small.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the physical-property value in an Example was measured by the method described below.
(1) Intrinsic viscosity of polymer IV
Measurement was performed at 25 ° C. using orthochlorophenol as a solvent.
(2) Wooster spots Using the USTER TESTER UT-4 manufactured by Zellweger, the average value during measurement for 5 minutes at a yarn speed of 100 m / min and a twist number of 8000 T / m was calculated to obtain Wooster spots (H%).
(3) Determination of yarn breakage Spinning simultaneously with 32 spindles and measuring the number of yarn breakage during spinning for 120 hours, ◎ if 1 or less, ○ if 2 or 3 times, Δ if 4 to 5 times, 6 times or more If it was x.

Example 1
The polyethylene terephthalate homopolymer pellets having a polymer intrinsic viscosity IV of 0.66 are dried to a moisture content of 70 ppm or less. The dried pellets were melted, and the outer diameter D1 of the nozzle D1 = 110 mm, the outermost diameter D2 of the spinneret D88 = 88 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, the PCDD4 = 3.0 mm of the discharge hole group, and the interval L = 7 mm, 3 rows annular array, 4 discharge holes per introduction hole, total number of discharge holes 288, 1 discharge holes perforated in the introduction hole are not aligned in the radial direction, and the separation band width W = 16 mm After being discharged at a polymer temperature of 292 ° C., it was cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and subsequently wound up at 4000 m / min to obtain a polyester ultrafine fiber having 80 dtex and 144 filaments. . As shown in Table 1, good results were obtained with respect to yarn breakage during spinning and Worcester spots of the obtained ultrafine fibers.

Example 2
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1. The outer diameter D1 of the die D = 75 mm, the outermost diameter D2 of the spinneret D2 = 60 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.5mm, L = 6mm, 2 rows annular arrangement, 8 discharge holes per introduction hole, total number of discharge holes 192, 1 discharge holes perforated in the radial direction are not aligned in the radial direction. After discharging at a polymer temperature of 292 ° C. from a die having a width W = 12 mm, the polymer is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and subsequently wound up at 4000 m / min to obtain 80 dtex, 96 filaments Polyester microfiber was obtained. As shown in Table 1, good results were obtained with respect to yarn breakage during spinning and Worcester spots of the obtained ultrafine fibers.

Example 3
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1, and the outer diameter D1 of the die D = 125 mm, the outermost diameter D2 of the spinneret D100 = 100 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.0 mm, polymer introduction hole row interval L = 6 mm, 6 rows annular array, 4 discharge holes per introduction hole, total number of discharge holes 384, 1 discharge holes drilled in the introduction holes are not aligned in the radial direction After discharging at a polymer temperature of 292 ° C. from a die having a separation band width W = 24 mm in two ridges, it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying an oil agent, and then wound up at 4000 m / min. As a result, a polyester ultrafine fiber of 80 dtex and 192 filaments was obtained. As shown in Table 1, good results were obtained with respect to yarn breakage during spinning and Worcester spots of the obtained ultrafine fibers.

Example 4
Polyester pellets similar to those in Example 1 were dried and melted in the same manner as in Example 1, and using the spinneret shown in FIG. 4, the outer diameter D1 = 125 mm of the spinneret, the outermost peripheral diameter D2 = 100 mm of the spinneret, and the diameter D3 of the polymer introduction hole = 3 6.0mm, discharge hole group PCDD4 = 5.0mm, polymer introduction hole row interval L = 8mm, two rows annular array, 5 discharge holes per introduction hole, total number of discharge holes 300, 1 introduction hole drilled The discharge holes are not arranged in the radial direction, and are discharged from a single base at a polymer temperature of 292 ° C., then cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and subsequently 4000 m / min. Was wound to obtain a polyester ultrafine fiber of 167 dtex, 300 filaments. As shown in Table 1, good results were obtained with respect to yarn breakage during spinning and Worcester spots of the obtained ultrafine fibers.

Comparative Example 1
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1, and the nozzle outer diameter D1 = 65 mm, the spinneret outermost diameter D2 = 45 mm, the polymer introduction hole diameter D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.0 mm, polymer introduction hole row interval L = 5 mm, 3 rows annular arrangement, 4 discharge holes per introduction hole, total discharge hole number 192, discharge holes perforated in one introduction hole are aligned in the radial direction After being discharged from a single base at a polymer temperature of 292 ° C., cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and then wound up at 4000 m / min to obtain 80 dtex, 192 filament Polyester microfiber was obtained. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

Comparative Example 2
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1. The outer diameter D1 of the die D = 75 mm, the outermost diameter D2 of the spinneret D2 = 60 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.0 mm, 1 row annular arrangement, 4 discharge holes per introduction hole, total number of discharge holes 192, 1 discharge holes perforated in the radial direction are not aligned in the radial direction, separation band width W = 10 mm After being discharged from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after application of the oil, and subsequently wound up at 4000 m / min to obtain 80 dtex, 96 filament polyester extra fine An attempt was made to obtain a fiber, but it was very difficult to divide the two yarn groups, and winding was impossible.

Comparative Example 3
Polyester pellets similar to those in Example 1 were dried and melted in the same manner as in Example 1. The nozzle outer diameter D1 = 110 mm, the spinneret outermost diameter D2 = 88 mm, the polymer introduction hole diameter D3 = 3.0 mm, and the PCDD4 of the discharge hole group = 2.4 mm, polymer introduction hole row interval L = 5 mm, 8-row annular arrangement, 3 discharge holes per introduction hole, total number of discharge holes 384, 1 discharge holes drilled in the introduction holes are not aligned in the radial direction The separation width W is 14 mm in two ridges. After discharging from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and then wound at 4000 m / min. As a result, a polyester fine fiber of 80 dtex and 192 filaments was obtained. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

Comparative Example 4
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1, and the outer diameter D1 of the nozzle D1 = 110 mm, the outermost diameter D2 of the spinneret D88 = 88 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.8 mm, polymer introduction hole row interval L = 6 mm, 5 rows annular array, 6 discharge holes per introduction hole, total number of discharge holes 384, 1 discharge holes drilled in the introduction holes are not aligned in the radial direction The separation width W is 14 mm in two ridges. After discharging from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and then wound at 4000 m / min. As a result, a polyester fine fiber of 80 dtex and 192 filaments was obtained. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

Comparative Example 5
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1, and the nozzle outer diameter D1 = 110 mm, the spinneret outermost diameter D2 = 88 mm, the polymer introduction hole diameter D3 = 5.0 mm, and the PCDD4 of the discharge hole group = 2.2 mm, polymer introduction hole row spacing L = 6 mm, 5 rows annular arrangement, 4 discharge holes per introduction hole, total number of discharge holes 384, 1 discharge holes drilled in the introduction holes are not aligned in the radial direction The separation width W is 14 mm in two ridges. After discharging from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and then wound at 4000 m / min. As a result, a polyester fine fiber of 80 dtex and 192 filaments was obtained. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

Comparative Example 6
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1. The nozzle outer diameter D1 = 110 mm, the spinneret outermost diameter D2 = 60 mm, the polymer introduction hole diameter D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.0 mm, polymer introduction hole row interval L = 7 mm, two rows annular arrangement, 4 discharge holes per introduction hole, total number of discharge holes 144, 1 discharge holes perforated in the introduction hole are not aligned in the radial direction The separation band width W is 12 (mm) at two ridges, and after discharging from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min. The polyester extra fine fiber of 60 dtex and 72 filaments was obtained by winding in minutes. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

Comparative Example 7
The same polyester pellets as in Example 1 were dried and melted in the same manner as in Example 1, and the outer diameter D1 of the nozzle D1 = 110 mm, the outermost diameter D2 of the spinneret D88 = 88 mm, the diameter D3 of the polymer introduction hole D3 = 4.0 mm, and the PCDD4 of the discharge hole group = 3.0 mm, polymer introduction hole row spacing L = 7 mm, three rows annular arrangement, four discharge holes per introduction hole, total number of discharge holes 288, and discharge holes perforated in the introduction hole are arranged in the radial direction The separation band width W is 16 mm in two ridges, and after discharging from the die at a polymer temperature of 292 ° C., it is cooled by an annular cooling device, taken up at a speed of 4020 m / min after applying the oil, and then wound at 4000 m / min. By taking, a polyester ultrafine fiber of 80 dtex, 144 filaments was obtained. As shown in Table 2, there were many yarn breaks during spinning, and Worcester spots of the obtained ultrafine fibers were also deteriorated.

It is a figure which shows an example of the spinneret of this invention. It is a figure which shows another example of the spinneret of this invention. It is a figure which shows an example of the expansion of the introduction hole part of the spinneret of Example 4 of this invention. It is a figure which shows an example of the conventional spinneret.

Explanation of symbols

1: Introduction hole 2: Discharge hole 3: Separation zone D1: Outer diameter D2: Spinneret outermost diameter D3: Polymer introduction diameter D4: PCD of discharge hole group
L: Row spacing of polymer introduction holes θ: Angle formed by lines connecting each discharge hole and the center of the nozzle in each group of discharge holes W: Width of separation band

Claims (6)

Following (1)-(8)
(1) A circular base having an outer diameter D1 of 75 to 125 mm,
(2) In the base, 2 to 6 rows of polymer introduction holes are arranged circumferentially,
(3) The relationship between D2 (mm) defined by twice the maximum value and the outer diameter D1 (mm) of the die, with the line connecting the center of the die and the center of the polymer introduction hole as the radius,
0.6 × D1 ≦ D2 ≦ 0.85 × D1
Satisfied,
(4) The relationship between the row interval L (mm) of the polymer introduction holes and the introduction hole diameter D3 (mm)
1.3 × D3 ≦ L ≦ 6 × D3
Satisfied,
(5) 2 to 8 discharge holes are drilled with respect to the one polymer introduction hole,
(6) D4 defined by twice the maximum value with the discharge hole perforated in the one polymer introduction hole as one group, and a line connecting the center of the polymer introduction hole and the center of the discharge hole as a radius (Mm) and the ratio of the polymer introduction hole diameter D3 (mm),
D4 / D3 = 0.5-0.9
Satisfied,
(7) Furthermore, the total number of ejection holes is 120 to 600 holes,
(8) The discharge holes in one group are arranged so as not to be aligned in the radial direction with respect to the center of the die.
A spinneret characterized by having the following requirements.   The spinneret according to claim 1, wherein the discharge holes in one group are formed concentrically.   The spinneret according to claim 1 or 2, wherein a separation band for two mountains is provided.   The spinneret according to claim 3, wherein the separation band width W (mm) = 12 to 24.   A method for producing ultrafine fibers, wherein the base according to any one of claims 1 to 4 is used, and spinning is performed using an annular cooling device.   The method for producing an ultrafine fiber according to claim 5, wherein the synthetic fiber is an ultrafine fiber having 60 to 600 filaments and a single yarn fineness of 0.2 to 1.0 dtex.

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