JP2009263805A - Rectangular spinneret, and method for producing synthetic fiber by using rectangular spinneret - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rectangular spinning pack capable of reducing occurrence of yarn break and quality unevenness of spun yarn, and to provide a method for producing a synthetic fiber. <P>SOLUTION: The rectangular spinneret having many nozzle holes is regulated so that the nozzle holes may be arranged in a rectangular region in which the nozzle holes are arranged so that the hole density may be reduced from the center part in the longitudinal direction of the rectangular region to the terminal part in the longitudinal direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rectangular spinneret for synthetic fibers and a method for producing synthetic fibers using a rectangular spinneret.

  As a spinning pack generally used for spinning synthetic fibers, a circular spinneret in which nozzle holes in the spinneret are arranged in a circular region of the base as shown in FIG. 2 is generally used. In the lower pack case, a filter medium, a perforated plate, and a circular spinneret are sequentially arranged in the direction of the entire flow of the polymer to be spun, and the filter medium, the perforated plate, and the circular spinneret are polymerized. An upper pack case having an inflow pipe is integrally assembled. The polymer is introduced from a polymer supply pipe into a polymer inflow pipe provided in the upper pack case, and is spun from a circular spinneret through a filter medium and a perforated plate.

  Spinning using this circular spinneret has been proposed for optimizing the hole arrangement, for example, as a countermeasure against problems such as adhesion between single yarns, yarn breakage, and thread-like quality spots (see, for example, Patent Document 1). Improvement measures have been taken to reduce yarn breakage and thickness unevenness in spinning using a circular spinneret.

  In recent years, the need for a spinneret that can increase the number of nozzle holes is increasing in response to the trend toward larger production machines due to improved productivity. As the shape of the spinneret, there is a rectangular spinneret (see, for example, Patent Document 2) in which nozzle holes in the spinneret as shown in FIG. By arranging the nozzle holes in a rectangular shape in this way, the shortest distance from the outer periphery of the base to the center of the base can be shortened, and the coagulating liquid can be easily supplied to the center of the base, so the number of nozzle holes can be increased. it can.

The configuration of the rectangular spinneret using the rectangular spinneret is the same as that of the circular spinneret, and in the lower pack case, in the order of the overall flow of the polymer to be spun, a filter medium, a perforated plate, A rectangular spinneret is disposed, and the filter medium, the perforated plate, and the rectangular spinneret are integrally assembled in an upper pack case having a polymer inflow pipe. The polymer is introduced from a polymer supply pipe into a polymer inflow pipe provided in the upper pack case, and is spun from a rectangular spinneret through a filter medium and a perforated plate. An example of a dry and wet spinning method using a rectangular spinneret is shown in FIG. FIG. 4A is a view as seen from the direction in which the yarn pull-out direction is front and rear, and FIG. 4B is a view as seen from the direction in which the yarn pull-out direction is right and left. In this example, the rectangular spinning pack 1 is installed horizontally with a certain air layer 3 between the coagulating bathtub 2. The spinning solution discharged from the rectangular spinning pack 1 is once extruded into the gas atmosphere (air layer 3) and then guided into the coagulation bath to become a coagulated yarn 4, which is taken up by a folding guide 5 installed at the bottom of the coagulation bath. The direction is changed and the take-out roller 6 pulls out the coagulation bath. The base is arranged so that its longitudinal direction is in the lateral direction in FIG. 4A, and the yarn is converged in the width direction of the base between the base and the folding guide, and is folded back by the folding guide in the form of a wide ribbon. Note that a rectifying plate may be installed in the coagulation bath 2 in order to rectify the accompanying flow generated by the yarn flow.
JP 7-278940 A JP 2001-348722 A

  However, the above-described rectangular spinneret has the following drawbacks.

  The above-mentioned Patent Document 2 arranges partial areas in a strip shape, and by providing a non-perforated area between adjacent partial areas, it is possible to smoothly enter the coagulating liquid, thereby increasing the number of nozzle holes. is there. However, when the coagulating liquid is locally poured into the non-perforated region, the flow of the coagulating liquid is disturbed and the yarn is shaken, which causes problems such as occurrence of thickness unevenness and thread breakage.

  An object of the present invention is to solve the above-described conventional problems, and to provide a rectangular spinneret and a synthetic fiber manufacturing method capable of reducing the occurrence of yarn breakage and spun yarn quality unevenness. .

  The present inventor has discovered the following phenomenon by observing in detail the liquid level immediately below the die when a conventional rectangular die is applied to dry and wet spinning.

  That is, FIG. 5 is an enlarged view of the vicinity of the liquid surface in the region where the yarn is discharged from the base from the direction of FIG. 4A, and FIG. 6 is an enlarged view of the region from the direction of FIG. In this wet and wet spinning, the yarn 4 discharged from the rectangular spinning pack 1 is guided into the coagulation bath as shown in FIGS. At that time, the coagulation liquid is pulled by the yarn 4 and flows along the yarn 4. On the other hand, in the vicinity of the water surface, a flow toward the central axis of the rectangular spinning pack 1 is generated to supplement the coagulating liquid pulled by the yarn. In particular, the yarn located in the outer peripheral portion is greatly affected by this flow, and the yarn is collected toward the central axis of the rectangular spinning pack 1, and the yarn density is increased in that region. In the region where the yarn density is increased, the amount of the coagulating liquid pulled by the yarn increases, so that the liquid level of the coagulating liquid decreases.

Under the hypothesis that such a decrease in the liquid level of the coagulation liquid and the resulting disturbance in the flow of the coagulation liquid may be the cause of defects such as thickness spots and thread breakage, we have studied to reduce this phenomenon. As a result, the present inventors have found a rectangular die that can greatly reduce thickness spots and thread breakage. That is, the rectangular base of the present invention has one of the following configurations.
(1) A spinneret having a large number of nozzle holes, wherein the nozzle holes are arranged in a rectangular region of the base surface with a lower hole density in the outer peripheral portion than the hole density in the central portion of the rectangular region. A rectangular spinneret characterized in that
(2) The rectangular region is divided into a plurality of partial regions, and in each divided partial region, the outer peripheral portion of the rectangular region is compared with the hole density of the partial region located in the central portion of the rectangular region. The rectangular spinneret according to (1), wherein the pore density in the partial region is low.
(3) The rectangular spinneret according to (2), wherein the hole density of the partial region located in the outer peripheral portion is 0.5 to 0.9 times the hole density of the central partial region.
(4) The rectangular spinneret according to (2) or (3), in which the hole density of the outer peripheral portion is lower than the hole density of the central portion of each partial region in each of the partial regions.
(5) A method for producing a synthetic fiber, comprising dry-wet spinning using the rectangular spinneret according to any one of (1) to (4).

  When the rectangular spinneret of the present invention is used, the yarn density of the yarn discharged from the partial region located on the outer peripheral portion of the rectangular spinneret during dry / wet spinning is partially increased, and the liquid level of the coagulating liquid is partially increased. It is possible to reduce the area where the temperature drops. This makes it possible to maintain a stable liquid level of the coagulation liquid, thereby improving thickness spots and reducing thread breakage, thereby greatly improving the quality and productivity of the synthetic fibers obtained. Can do.

  The present invention relates to a rectangular base in which a large number of nozzle holes are provided in a rectangular region of the base surface. The present invention aims at improving the productivity of synthetic fibers by dry and wet spinning, and is for a rectangular spinneret that can further increase the number of nozzle holes. When the number of nozzle holes is 1000 or more, A preferable effect is obtained. The upper limit of the number of nozzle holes is not particularly limited, but is preferably 15000 or less due to equipment limitations associated with the increase in size of the die.

  The rectangular spinneret according to the present invention is characterized in that the nozzle holes are arranged in a rectangular region of the base surface such that the hole density of the outer peripheral portion is lower than the hole density of the central portion of the rectangular region.

  Here, the rectangular region does not require geometrical strictness as a shape, and may be a shape whose width direction is narrower than the longitudinal direction. In the present invention, the following conditions are satisfied. Is defined as a rectangle. That is, considering a rectangle inscribed and circumscribed to an outer shape of a certain shape (whose area is S), Si is the area of the rectangle that has the largest area among the inscribed rectangles, and the area of the circumscribed rectangle is The area of the smallest rectangle is defined as So, and a shape satisfying 0 ≦ (S−Si) /S≦0.27 or 0 ≦ (So−S) /S≦0.27 is defined as a rectangle. Preferably 0 ≦ (S—Si) /S≦0.25, or 0 ≦ (S—Si) /S≦0.25, more preferably 0 ≦ (S—Si) /S≦0.20, Alternatively, a shape satisfying 0 ≦ (So−S) /S≦0.20 is defined as a rectangle. As long as the above conditions are satisfied, a shape with rounded corners, a shape with dropped corners, a dumbbell shape with a depression in the center in the longitudinal direction, a polygon with five or more vertices, Even a long round shape with rounded corners connected on the short side in a rectangle can be treated as a rectangle, and the present invention can be suitably applied to both. Furthermore, as long as the outer shape of the region is the above rectangle, it may have a region in which no nozzle hole is formed, and even if it is a donut shape or a glasses shape, the range that satisfies the above conditions If so, the present invention can be preferably applied.

  Further, in the present invention, the region in which the nozzle holes are arranged in the rectangular region of the base surface refers to the entire region enveloping the outermost nozzle hole, and may be divided by a non-perforated region. The region where the entire nozzle hole of the die surface including the non-perforated region exists is indicated. Note that a portion where the region is divided by the non-perforated region is distinguished from this and is referred to as a “partial region”. For example, in FIG. 2, the “region in which the nozzle holes are arranged” is a circular region, the “partial region” indicates a segmented fan-shaped region, and in FIG. The “region” is a region including all of E, E ′, F, and F ′, and each of E, E ′, F, and F ′ is a partial region.

  The rectangular die of the present invention is characterized in that the hole density in the outer peripheral part is lower than the hole density in the central part of the rectangular region. In the present invention, the hole density in the central part and the outer peripheral part is a hole density within a range satisfying the following conditions. The hole density in the central part is a similar shape having the same center as the rectangle, and the area is an average of the hole density in a range that is 1/15 of the rectangle (sometimes referred to as the central part representative range). In this case, the hole density of the outer peripheral part means the hole density obtained by averaging the range of the width of 10 mm from the outermost periphery (sometimes referred to as the outer peripheral part representative range). In addition, when the said center part representative range or the said outer peripheral part representative range contains a non-perforated area | region, the average hole density about those ranges except a non-perforated area is calculated as a hole density of the part. Shall. In addition, when the interval between nozzle holes in the central part or the outer peripheral part (also referred to as pitch) is uniform, the average hole density in these ranges is set using the nozzle hole pitch as described later. In the case where the central portion representative range or the outer peripheral portion representative range is divided by a non-perforated region, and the nozzle hole intervals are uniform in each of the divided ranges. The average hole density in each range may be obtained from the nozzle hole pitch, and the average hole density in each representative range may be obtained as an average weighted by the area.

  In the present invention, the hole density may be low and the nozzle hole may be disposed only at the outer peripheral portion as long as the outer peripheral portion in the longitudinal direction is disposed lower than the central portion of the rectangular region. Nozzle holes may be arranged so that the hole density changes from the whole to the outer peripheral part. When changing the hole density throughout, the nozzle holes may be arranged so that the hole density continuously changes from the central part to the outer peripheral part, or the hole density changes stepwise. Nozzle holes may be arranged. Moreover, it is preferable that the hole density of an outer peripheral part is 0.5 to 0.9 times the hole density of a center part. Even when the arrangement is such that the hole density continuously changes, the average hole density of the outer peripheral portion representative range is 0.5 to 0.9 of the average hole density of the central portion representative range. It is preferable to double. Further, from the end in the longitudinal direction, the nozzle hole is arranged from the end in the width direction of 5.0% to 22.5% of the length X in the longitudinal direction of the rectangular region in which the nozzle hole is arranged. In the range of 5.0% to 22.5% of the length Y in the width direction of the rectangular area, the average hole density is 0.5 to 0.9 times the hole density of the central representative range It is preferable that a region exists.

In the present invention, when the nozzle holes are arranged in a lattice shape, the hole density is 1 when the horizontal pitch of the nozzle holes is Ph (mm) and the vertical pitch is Pv (mm). / (Ph × Pv) (pieces / mm ² ). Further, when the nozzle holes are arranged in a staggered pattern, the hole density is defined as 0.5 / St (piece / piece), where St is the area of a triangle formed by connecting the central axes of three adjacent nozzle holes. mm ² ). In addition, when determining the hole density at a specific location when the nozzle hole arrangement does not have regularity such as a lattice shape, the number of nozzle holes included in a 100 mm ² square with one side being 10 mm is measured, By dividing by 100 mm ² , the number of nozzle holes per 1 mm ² is expressed. In such a case, when a 100 mm ² square portion having one side of 10 mm includes a non-perforated region, the non-perforated region is It shall be calculated without including. The hole pitch of the rectangular spinneret of the present invention is preferably in the range of 0.6 to 4.0 mm, more preferably 2.0 to 3.0 mm.

  Further, as an example of a preferred aspect of the present invention, the rectangular area is divided into a plurality of partial areas, and in each divided partial area, a partial area (hereinafter referred to as a central part) positioned at the central part of the rectangular area. In some cases, the pore density of a partial region (hereinafter also abbreviated as an outer peripheral portion region) located in the outer peripheral portion of the rectangular region is low. It is preferable from the viewpoint of the manufacturability of the die that a non-perforated region having no nozzle hole is provided between the partial regions, and that the non-perforated region is divided into partial regions. In the conventional technique, when a non-perforated region is provided, the coagulating liquid locally flows into the non-perforated region, thereby disturbing the flow of the coagulating liquid and causing the yarn to shake. It was a thing. By applying the present invention, a non-perforated region can be provided without causing a problem as in the prior art, and the manufacturability of the die can be improved. However, as described above, the local flow of the coagulating liquid into the non-perforated region induces yarn swaying and causes defects such as the occurrence of thick spots and thread breakage, so that the width is too wide. That is not preferable. Therefore, the width of the non-perforated region is 1.5 times or more the outermost hole pitch of the adjacent partial region, and the absolute value is preferably 1.0 mm to 6.0 mm, and preferably 3.0 mm to 4 More preferably, it is 0.5 mm.

In this invention, it is preferable that the hole density of the said outer peripheral part partial area is 0.5 to 0.9 times the hole density of the said center partial area. When the hole density of the outer peripheral region is smaller than 0.5 times the hole density of the central partial region, the yarn density of the yarn discharged from the central partial region is higher than the yarn density discharged from the outer peripheral region. On the other hand, when it is higher than 0.9 times, the yarn density of the yarn discharged from the outer peripheral portion region is high, and in any condition, the liquid level is locally in the region where the yarn density is high. This is because the effect of the present invention may not be sufficiently obtained. The longitudinal length X ₁ of the outer peripheral portion region of the longitudinal rectangular area where the nozzle holes are arranged is 5.0% to 22.5% of the length X, the outer peripheral portion region the length Y ₁ in the width direction is preferably the width direction of a region where the nozzle holes are arranged is 5.0 to 22.5% of the length Y.

  The synthetic fiber production method of the present invention is a production method in which dry spinning is performed using the rectangular spinneret. By using the rectangular spinneret of the present invention, it is possible to eliminate the difference in level of the coagulating liquid, and to perform stable spinning without causing unevenness in the thickness of the yarn or breakage of the yarn.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic plan view showing an example of a hole density distribution of nozzle holes in a rectangular spinneret according to the present invention. In this example, in the rectangular spinneret, the hole density decreases from the center to the outer periphery. More specifically, as shown in FIG. 1A, the interval between adjacent nozzle holes is arranged so as to increase in the longitudinal direction and the width direction from the central part toward the outer peripheral part side, and is a rectangle in which the nozzle holes are arranged. Are symmetrical with respect to a center line M orthogonal to the longitudinal direction of the region and a center line N orthogonal to the width direction of the nozzle hole group. The interval between the nozzle holes is not particularly limited, but it is preferable that the degree of congestion (hereinafter referred to as yarn density) in the discharged yarn space is constant, and is constant as in the example of FIG. 1A. It is preferable to arrange so that it may become large in the ratio. By making the yarn density uniform, the amount of the coagulation liquid pulled by the yarn can be made uniform, and the liquid level of the coagulation liquid from the direction perpendicular to the longitudinal direction of the rectangular spinning pack as shown in FIG. Further, as shown in FIG. 8, when the liquid level of the coagulation liquid is viewed from the direction perpendicular to the width direction of the rectangular spinning pack, the liquid level of the coagulation bath can be kept at a stable liquid level with little difference in height. Therefore, thread breakage and thickness unevenness can be reduced.
FIG. 9 is a schematic plan view showing an example of a rectangular spinneret according to the present invention. In FIG. 9, a rectangular region in which nozzle holes are arranged is divided into nine partial regions, and a non-perforated region without nozzle holes is provided between adjacent partial regions. In this example, the outer peripheral portion partial area is arranged so as to surround one central partial area. The shape of each partial region is axisymmetric with respect to a center line M orthogonal to the longitudinal direction of the rectangular region in which the nozzle holes are arranged and a center line N orthogonal to the width direction of the nozzle hole group. The nozzle hole density in each partial region may decrease from the center of each partial region toward the outer periphery of each partial region, but may be uniform as shown in FIG. 9A. It is preferable that the hole density (b) of the outer peripheral partial region is 0.5 to 0.9 times the hole density (a) of the central partial region. When the hole density (b) of the outer peripheral part region is larger than 0.9 times the hole density (a) of the central part region, an area where the yarn density of the yarn discharged from the outer peripheral part region is increased In the region where the yarn density cannot be eliminated and the yarn density in the outer peripheral portion is high, the liquid level is greatly reduced locally, and the effects of the invention may not be sufficiently obtained. When the hole density (b) of the outer peripheral region is smaller than 0.5 times the hole density (a) of the central partial region, the yarn density of the yarn discharged from the central partial region is The density is preferably higher than the density of the yarn to be discharged, and the central liquid level may be lower than the liquid level at the outer peripheral portion. The longitudinal length X ₁ of the outer peripheral portion region of the longitudinal rectangular area where the nozzle holes are arranged is 5.0% to 22.5% of the length X, the outer peripheral portion region the length Y ₁ in the width direction is preferably the width direction of the rectangular area where the nozzle holes are arranged from 5.0% to 22.5% of the length Y. The length X ₁ in the longitudinal direction of the outer peripheral portion region and the length Y ₁ in the width direction of the outer peripheral portion region are the length X in the longitudinal direction and the length Y in the width direction of the rectangular region in which the nozzle holes are arranged. If it is less than 5.0%, the partial area is too small, and the effects of the invention may not be sufficiently obtained. Further, longitudinal length X ₁ and width direction length Y ₁ of the outer peripheral portion region, the longitudinal direction of the rectangular area where the nozzle holes are arranged in a length X and a width direction length Y 22. The effect of the invention can be obtained even when the ratio is larger than 5%, but it is not preferable because the size of the rectangular base must be increased in order to obtain the same number of nozzle holes, and the equipment is increased in size.

  By arranging the partial areas in this way and making the hole density (b) of the outer peripheral part area smaller than the hole density (a) of the central partial area, the longitudinal direction of the rectangular spin pack as shown in FIG. When the liquid level of the coagulating liquid is viewed from the vertical direction and when the liquid level of the coagulating liquid is viewed from the vertical direction with respect to the width direction of the rectangular spinning pack as shown in FIG. The density can be made uniform. Therefore, the liquid level can be maintained at a stable liquid level with little difference in height, and thread breakage and thickness unevenness can be reduced.

Further, the outer peripheral portion region and the central partial region may be further divided into a plurality of portions in the longitudinal direction and the width direction of the rectangular region as shown in FIG. The sum X ₁ ′ is 5.0% to 22.5% of the length X in the longitudinal direction of the rectangular region in which the nozzle holes are arranged, and the sum Y ₁ ′ of the length in the width direction of the outer peripheral portion region. Is preferably 5.0% to 22.5% of the length X in the width direction of the rectangular region in which the nozzle holes are arranged. The distribution of the hole density is not limited to two stages. For example, as shown in FIG. 13, the hole density decreases from the center partial region toward the outer peripheral portion region so that the hole density a>b> c. It is also a preferable aspect to obtain a sufficient effect.

The shape of the partial area in the rectangular spinneret is not limited to a rectangle. For example, even if the partial areas are divided into trapezoidal or triangular shapes as shown in FIG. 14, the shape of each partial area is the center line M and nozzles orthogonal to the longitudinal direction of the rectangular area in which the nozzle holes are arranged. The line is symmetrical with respect to the center line N orthogonal to the width direction of the hole group, the hole density (b) of the outer peripheral part region is smaller than the hole density (a) of the central partial area, and the length of the outer peripheral part region is long. direction length X ₁ is 5.0% to 22.5% of the longitudinal length X of the rectangular area where the nozzle holes are arranged, the width direction of the length Y ₁ of the outer peripheral portion region If it is divided so as to be 5.0% to 22.5% of the length Y in the width direction of the rectangular region in which the nozzle holes are arranged, it is a preferable mode for obtaining a sufficient effect. Furthermore, if the region where the nozzle holes are arranged satisfies the above-mentioned rectangular condition, the shape of the partial region divided by the non-perforated region is not limited to a rectangle or a triangle, and is a shape such as an ellipse or a polygon. However, the present invention can be preferably applied as long as it satisfies the above conditions.

  The rectangular spin pack using the rectangular spinneret of the present invention is particularly effective for a polymer solution having a viscosity of 5 to 5,000 Pa · s, and synthetic fibers are produced by dry and wet spinning using the rectangular spinneret of the present invention. Thus, the level difference in the level of the coagulation liquid is eliminated, and stable spinning can be performed without causing unevenness in the thickness of the yarn or thread breakage. Further, in the melt spinning method, it is useful to make the yarn density uniform in terms of uniform cooling of the yarn, and in wet spinning, the uniformity of the concentration of the coagulation bath closest to the die, and the rectangular spinning die of the present invention is useful. Can be applied not only to the dry and wet spinning method but also to the melt spinning method and the wet spinning method, and the spinning method is not particularly limited.

    Hereinafter, the effects of the present invention will be specifically described with reference to examples, but the embodiments according to the present invention are not limited to the examples.

  In this example, dry and wet spinning was carried out, and the yarn density of the discharged yarn and the decrease distance of the coagulating liquid level were measured. Each measuring method is as follows, and from these, a yarn density difference of 10% or less was evaluated as ○, and a yarn exceeding 10% was determined as △. Further, a drop distance of 1 mm or less on the liquid level was judged as ◯, and those exceeding 1 mm were judged as Δ.

<Measurement of yarn density of discharged yarn>
As shown in FIG. 15, the underwater camera 8 is fixed to the underwater camera fixing jig 7 fixed on the rectangular spinning pack 1 horizontally in the coagulation bath. An image taken by the underwater camera 8 was sent to a personal computer 9, and the number of yarns included within a range of 30 mm in width was measured from the image, and the yarn density (lines / mm) was calculated.

  The measurement location in the longitudinal direction of the yarn density of the yarn was performed in the region shown in FIG. First, looking at the discharge region from the direction perpendicular to the longitudinal direction of the rectangular spinning pack, the origin is the point where the center of the longitudinal length X of the rectangle in which the nozzle holes are arranged and the discharge surface of the rectangular spinning pack intersect, The horizontal direction is the x-axis, the direction passing through the origin and the vertical direction is negative is the z-axis. The coordinates of the end of the longitudinal nozzle hole were (x, z) = (± 0.5X, 0) (unit: mm, hereinafter omitted). The measurement point is a measurement of the yarn discharged from the outer peripheral portion region by measuring a region centered at (x, z) = (0, −8) as a measurement portion of the yarn discharged from the central partial region. As the locations, two locations in a region centered at (x, z) = (0.4X, −8) and (x, z) = (− 0.4X, −8) were measured. Moreover, it measured similarly to the longitudinal direction also about the measurement location of the width direction. Looking at the discharge area from the direction perpendicular to the width direction of the rectangular spinning pack, the origin is at the point where the center of the length Y in the width direction of the rectangle in which the nozzle holes are arranged intersects the discharge surface of the rectangular spinning pack, and the horizontal direction Is the y-axis, the direction passing through the origin and the negative vertical direction is the z-axis. The coordinates of the width direction nozzle hole end were (y, z) = (± 0.5Y, 0) (unit: mm, hereinafter omitted). The measurement point is a measurement of a yarn discharged from the outer peripheral portion area by measuring a region around (y, z) = (0, −8) as a measurement portion of the yarn discharged from the central partial region. As the locations, two locations in a region centered at (y, z) = (0.4Y, −8) and (y, z) = (− 0.4Y, −8) were measured.

<Measurement of drop distance of coagulating liquid>
As shown in FIG. 17, the underwater camera 8 is fixed to the underwater camera fixing jig 7 placed on the rectangular spinning pack 1 so that the liquid level of the coagulation bath becomes the center of the image. An image photographed by the underwater camera 8 was sent to the personal computer 9, and the reduction distance of the coagulating liquid level was calculated from the image.

The measurement location of the drop distance of the coagulating liquid level was performed in the region shown in FIG. First, when the discharge region is viewed from the direction perpendicular to the longitudinal direction of the rectangular spinning pack, the center of the length X of the nozzle hole group in the longitudinal direction intersects the discharge surface of the rectangular spinning pack, and the horizontal direction Is the x-axis, the direction passing through the origin and the negative vertical direction is the z-axis. The coordinates of the end of the longitudinal nozzle hole were (x, z) = (± 0.5X, 0). The measurement location is a measurement location at a point where the liquid level is lowered by the yarn discharged from the central partial region, a point where the liquid level is crossed on x = 0 is measured, and the yarn discharged from the peripheral partial region As the measurement points of the point where the liquid level is lowered due to the stripe, two points of the point where the liquid level intersects on x = 0.4X and x = −0.4X were measured. Moreover, it measured similarly to the longitudinal direction also about the measurement location of the width direction. When the discharge region is viewed from the direction perpendicular to the width direction of the rectangular spinning pack, the origin is the point where the center of the rectangular width Y of the nozzle hole group intersects the discharge surface of the rectangular spinning pack, and the horizontal direction is y A direction passing through the axis and the origin and having the vertical direction negative is defined as the z-axis. The coordinate of the width direction nozzle hole end was (y, z) = (± 0.5 Y, 0). The measurement point is a point where the liquid level is lowered by the yarn discharged from the central partial region, the point where the liquid level crosses on y = 0 is measured, and the yarn discharged from the peripheral partial region As the measurement points of the point where the liquid level was lowered due to the strip, two points of the point where the liquid level intersected on y = 0.4Y and y = −0.4Y were measured.
Example 1
An acrylic polymer solution using a rectangular spinneret having a pore density distribution shown in FIGS. 19 and 20, wherein the pore density decreases from the center to the longitudinal end as shown in FIG. 1. The dry and wet spinning shown in FIG. 4 was performed, and the coagulated yarn was wound up. Dimethyl sulfoxide (DMSO) was used as the solvent, the density of the solution was 1085 kg / m ³ , and the viscosity was 120 Pa · s. The coagulation bath was a 30 wt% DMSO aqueous solution, and the take-up speed was 20 m / min. Further, the length X in the longitudinal direction of the rectangular area where the nozzle holes are arranged is 320 mm, and the length Y in the width direction of the rectangular area where the nozzle holes are arranged is 110 mm. The conditions and results at this time are shown in Table 1. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 0, and the quality was good.

The yarn density difference (%) in the longitudinal direction is a region centered at (x, z) = (0.4X, −8) and (x, z) = (− 0.4X, −8). The average value of the yarn density is divided by the yarn density in the region centered at (x, z) = (0, −8) and multiplied by 100. Similarly, the yarn density difference in the width direction (%) And (y, z) = (0.4Y, −8) and (y, z) = (− 0.4Y, −8) are average values of yarn densities in the center, and (y, z) ) = Divided by the yarn density in the region centered at (0, −8) and multiplied by 100. The height difference (mm) of the coagulating liquid level in the longitudinal direction is the decrease distance (mm) of the coagulating liquid level on x = 0, and the coagulation on x = 0.4X and x = −0.4X. This is the difference from the average drop distance (mm) of the liquid level. Similarly, the difference in level (mm) of the liquid level of the coagulating liquid in the width direction is the liquid level of the coagulating liquid at y = 0. Is the difference between the average drop distance (mm) and the average drop distance (mm) of the coagulating liquid at y = −0.4Y and y = −0.4Y.
(Example 2)
Dry and wet spinning was performed under the same conditions as in Example 1 except that the lengths of X and Y were different, and the yarn density difference of the yarn and the level difference of the coagulating liquid level were measured. The results are shown in Table 1. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 0, and the quality was good.

  As can be seen from Table 1, when the rectangular spinneret to which the present invention is applied is used, the difference in the yarn density of the discharged yarn is small, and the level difference in the liquid level of the coagulating liquid can be reduced.

(Example 3)
Using the rectangular spinneret in which the partial region shown in FIG. 9 was divided into a grid pattern, the dry and wet spinning shown in FIG. 4 was performed, and the coagulated yarn was wound up. Also, the length X in the longitudinal direction of the rectangular area where the nozzle holes are arranged is 320 mm, the length Y in the width direction of the rectangular area where the nozzle holes are arranged is 110 mm, and the length in the longitudinal direction of the outer peripheral part area X ₁ is 20% of the longitudinal length X of the rectangular area where the nozzle holes are arranged, the width direction of the length Y ₁ of the outer peripheral portion region in the width direction of the rectangular area where the nozzle holes are arranged 20% of the length Y, the pore density of the central partial region was 0.25 / mm, and the average pore density of the peripheral partial region with respect to the central partial region was 0.8 times. Table 2 shows the conditions and results at this time. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 0, and the quality was good.
(Examples 4 to 5)
Dry and wet spinning was performed in the same manner as in Example 1 except that the ratio of the hole density of the outer peripheral portion region to the central portion region was different, and the coagulated yarn was wound up. Table 2 shows the conditions and results at this time. As a result of measuring 100 m of the coagulated yarn, the number of fluffs was 3 in the case of Example 4 and 5 in the case of Example 4, and the quality was good.
(Example 6)
Dry and wet spinning was performed in the same manner as in Example 1 except that the number of partial regions was different, and the coagulated yarn was wound up. Table 2 shows the conditions and results at this time. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 0, and the quality was good.
(Example 7)
Dry and wet spinning was performed in the same manner as in Example 10 except that the length X ₁ in the longitudinal direction of the outer peripheral portion region and the length Y ₁ in the width direction of the outer peripheral portion region were different, and the coagulated yarn was wound up. Table 2 shows the conditions and results at this time. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 4, and the quality was good.
(Example 8)
Dry and wet spinning was performed in the same manner as in Example 1 except that a rectangular spinneret in which the partial region shown in FIG. 14 was divided into trapezoidal or triangular shapes was used, and the coagulated yarn was wound up. Table 2 shows the conditions and results at this time. As a result of measuring the coagulated yarn for 100 m, the number of fluffs was 0, and the quality was good.

As can be seen from Table 2, when the rectangular spinneret to which the present invention is applied is used, the difference in the yarn density of the discharged yarn is small, and the difference in level of the coagulating liquid can be reduced.
(Comparative Example 1)
Using the conventional rectangular die shown in FIG. 3, dry and wet spinning was performed under the same conditions as in Example 1, and the difference in yarn density between the yarns and the difference in the level of the coagulating liquid were measured. The rectangular length X of the rectangular spinneret nozzle group is 320 mm and the width Y is 110 mm, and the hole density and shape of each partial region are uniform.
At this time, the yarn density difference in the longitudinal direction of the discharged yarn was 38.5%, and the yarn density difference in the width direction was 35.4%. Further, the level difference of the liquid level of the coagulating liquid in the longitudinal direction was 3.26 mm, and the level difference of the liquid level of the coagulating liquid in the width direction was 3.09 mm. Further, it was clearly observed that the yarns were dense and caused a difference in level in the coagulating liquid. As a result of measuring 100 m of the coagulated yarn, the number of fluffs was 30 and the quality was poor. .

It is a schematic plan view which shows an example of the rectangular spinneret of this invention. It is a schematic plan view which shows the detail of the hole distribution of the rectangular spinneret shown in FIG. It is a schematic plan view which shows the conventional circular spinneret. It is a schematic plan view which shows the conventional rectangular spinneret. It is a schematic process drawing which shows one embodiment of a dry-wet spinning process. It is the side view which looked at the rectangular spinning pack discharge part from the direction perpendicular | vertical with respect to the rectangular spinning pack longitudinal direction explaining the liquid level fluctuation | variation of a coagulation bath in a dry-wet spinning process. It is the side view which looked at the rectangular spinning pack discharge part from the direction perpendicular | vertical with respect to the rectangular spinning pack width direction explaining the liquid level fluctuation | variation of a coagulation bath in a dry-wet spinning process. FIG. 2 is a side view of a rectangular spin pack discharging unit viewed from a direction perpendicular to the longitudinal direction of the rectangular spin pack when the rectangular spinneret shown in FIG. 1 according to the present invention is used. FIG. 2 is a side view of a rectangular spin pack discharging unit viewed from a direction perpendicular to the rectangular spin pack width direction when the rectangular spinneret shown in FIG. 1 according to the present invention is used. It is a schematic plan view explaining an example of this invention shape. FIG. 10 is a schematic plan view showing details of hole distribution of the rectangular spinneret shown in FIG. 9. FIG. 10 is a side view of the rectangular spin pack discharging unit viewed from a direction perpendicular to the longitudinal direction of the rectangular spin pack when the rectangular spinneret shown in FIG. 9 according to the present invention is used. FIG. 10 is a side view of the rectangular spin pack discharging unit viewed from a direction perpendicular to the rectangular spin pack width direction when the rectangular spinneret shown in FIG. 9 according to the present invention is used. It is a schematic plan view explaining an example of this invention shape. It is a schematic plan view explaining an example of this invention shape. It is a schematic plan view explaining an example of this invention shape. The side view which shows an example of the apparatus which measures the yarn density of the thread discharged from the nozzle | cap | die. It is a side view explaining the location which measures the yarn density of the thread discharged from the nozzle | cap | die. The side view which shows an example of the apparatus which measures the liquid level of a coagulation liquid. It is a side view explaining the location which measures the height of the liquid level of a coagulation liquid. Hole density distribution of rectangular spinneret used in Examples 1 and 2 Hole density distribution of rectangular spinneret used in Examples 1 and 2

Explanation of symbols

1: rectangular spinning pack 2: coagulation bath 3: air layer 4: yarn 5: folding guide 6: take-up roller 7: underwater camera fixing jig 8: underwater camera 9: personal computer
E: Partial area where nozzle holes are arranged E ′: Partial area where nozzle holes are arranged F: Partial area where nozzle holes are arranged F ′: Partial area where nozzle holes are arranged X: Nozzle holes are arranged Length X ₁ in the longitudinal direction of the rectangle: Length X ₁ ′ in the longitudinal direction of the partial region of the end portion Y: Sum of lengths in the longitudinal direction of the partial region of the end portion Y: Width direction of the rectangle in which the nozzle holes are arranged Length Y ₁ : length Y ₁ ′ in the width direction of the partial region of the end portion M: sum of lengths in the width direction of the partial region of the end portion M: center perpendicular to the longitudinal direction of the rectangle in which the nozzle holes are arranged Line N: Center line orthogonal to the longitudinal direction of the rectangle in which the nozzle holes are arranged p: Width of the non-perforated region

Claims (5)

A spinneret having a large number of nozzle holes, wherein the nozzle holes are arranged in a rectangular region of the base surface with a lower hole density at the outer periphery than the hole density at the center of the rectangular region. Characteristic rectangular spinneret. The rectangular area is divided into a plurality of partial areas, and in each divided partial area, a portion located at the outer peripheral portion of the rectangular area with respect to the hole density of the partial area located at the central portion of the rectangular area The rectangular spinneret according to claim 1, wherein the pore density in the region is low. 3. The rectangular spinneret according to claim 2, wherein the hole density of the partial region located in the outer peripheral portion is 0.5 to 0.9 times the hole density of the central partial region. The rectangular spinneret according to claim 2 or 3, wherein in each of the partial regions, the hole density in the outer peripheral portion is lower than the hole density in the central portion of each of the partial regions. A method for producing a synthetic fiber, comprising dry-wet spinning using the rectangular spinneret according to any one of claims 1 to 4.

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