Spinning nozzle

Abstract

To provide a spinning nozzle which is difficult to cause filament breakage and filament-to-filament fusions even when the number of holes is increased.SOLUTION: In a spinning nozzle 100 having a plurality of holes in block portions 7 which are formed by plural partitions of a nozzle surface 1, the block portions 7 each have such a shape that width thereof enlarges from a center 5 of the nozzle surface 1 toward a circumference of the nozzle surface 1, being present in a circumferential direction with the center 5 as a standard with gaps therebetween, and the block portion 7 has a caving part 11 which caves from the circumference edge toward the center 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a nozzle for producing chemical fibers by a spinning process. [Background technology]

[0002] There are various methods for manufacturing chemical fibers such as acrylic fibers. Among them, spinning methods such as wet spinning and dry spinning, in which a spinning dope containing a polymer is extruded through the discharge holes (hereinafter also called holes) of a spinning nozzle, have been industrially put into practical use. Among them, the wet spinning method is commonly used from the viewpoint of productivity. This wet spinning method is a method in which a polymer solution, which is a spinning dope, is discharged and coagulated into a coagulating liquid, which is a mixture of a solvent and water, to form fibers. There are two types of wet spinning: the narrow wet spinning method in which the spinning dope is discharged directly from the spinning nozzle into the coagulating liquid, and the dry wet spinning method in which the spinning dope is discharged from the spinning nozzle into the gas phase (usually into the air). In such a spinning method, the spinning solution is discharged from a spinning nozzle and taken up as a fiber bundle, which is an aggregate of single fibers (filaments) formed into a fibrous form, but if the density of the discharge holes of the spinning nozzle is increased and the number of fibers constituting the fiber bundle is increased, a difference in the coagulation speed is likely to occur between the outer periphery and the center of the discharge hole group, and unevenness in denier (fineness) and coagulation unevenness are likely to occur. In addition, although increasing the density of the discharge holes of the spinning nozzle is effective in terms of improving productivity, there are problems in that filaments are more likely to fuse together and filaments are more likely to be cut, i.e., so-called single yarn breakage. In order to solve such problems, various studies have been conducted, and for example, a spinning nozzle has been proposed that is "a circular nozzle for wet spinning consisting of a plurality of approximately sector-shaped perforated regions formed from the center of a circular nozzle to the outer periphery, and a plurality of non-perforated regions formed between the plurality of approximately sector-shaped perforated regions, characterized in that the sector-shaped perforated regions have discharge holes perforated at predetermined intervals on concentric circles equally spaced from each other and centered on the center of the circular nozzle, and the non-perforated regions are formed to have approximately the same width from the outer periphery to the center of the circular nozzle" (Patent Document 1). By using the nozzle of Patent Document 1, high-quality fibers with little denier unevenness, coagulation unevenness, etc. can be produced with good productivity. However, in recent years, there has been a demand to increase the number of holes (the above-mentioned discharge holes) in order to further increase productivity. However, simply increasing the number of holes increases the frequency of filament breakage, or so-called single yarn breakage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-348723 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a spinning nozzle in which filaments are less likely to break even if the number of holes is increased. [Means for solving the problem]

[0005] The spinning nozzle of the present invention is a spinning nozzle having a plurality of holes in a block section which divides the nozzle surface into a plurality of sections, the block sections have a shape in which their width increases from the center of the nozzle surface toward the outer periphery of the nozzle surface, and they exist at intervals in the circumferential direction based on the center, and the block sections have a recessed portion which recesses from the outer periphery toward the center. Effect of the Invention

[0006] According to the spinning nozzle of the present invention, even if the number of holes is increased, breakage of the filaments can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the inside of a spinning nozzle according to an embodiment. [Diagram 2] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Summary> A first spinning nozzle according to one aspect of the embodiment has a block section that divides the nozzle surface into a plurality of sections and has a plurality of holes. The block section has a shape in which its width increases from the center of the nozzle surface toward the outer periphery of the nozzle surface, and exists at intervals in the circumferential direction with respect to the center. The block section has a recessed portion that recesses from the outer periphery toward the center. This makes it possible to suppress filament breakage even if the number of holes is increased. Also, by providing the recessed portion, filament fusion can be suppressed. A second spinning nozzle according to another aspect of the embodiment is a first spinning nozzle, in which the holes are formed on a virtual arc located within the block portion and on multiple concentric circles centered on the center, and the length of the recessed portion is 0.65 times or less the length between the outer peripheral edge and the center. A third spinning nozzle according to another aspect of the embodiment is the first or second spinning nozzle, in which the interval between the circumferentially adjacent block portions is 1.5 mm or more. A fourth spinning nozzle relating to another aspect of the embodiment is a first or second spinning nozzle, in which the spacing between adjacent block portions in the circumferential direction is 1.5 mm or more, and the circumferential width of the recessed portion is smaller than the spacing between the block portions and is 0.95 mm or more. In a fifth spinning nozzle according to another aspect of the embodiment, the total number of the holes present on the nozzle surface in the first to fourth spinning nozzles is 18,000 or more. A sixth spinning nozzle according to another aspect of the embodiment is the first to fifth spinning nozzles, in which the number of the block portions is 30 or more. A sixth spinning nozzle according to another aspect of the embodiment is such that, in the first to fifth spinning nozzles, the minimum pitch of the holes formed on the imaginary arc is 0.35 mm or more.

[0009] <Embodiment> The spinning nozzle described in the embodiment has block sections of a sector shape, a triangle shape, or similar shape whose circumferential dimensions increase from the center toward the radially outward direction, and holes are formed in the block sections. However, it was discovered that by providing recessed portions without holes in the block sections, filaments are less likely to break even if the number of holes is increased, and high-quality fibers without fusion between filaments can be obtained, which led to the completion of the present invention.

[0010] 1. Overall structure The spinning nozzle (hereinafter simply referred to as "nozzle") will be described with reference to Figs. 1 and 2. The nozzle 100 has a nozzle surface 1 and a large number of spinning holes 3 provided on the nozzle surface 1. Fig. 1 is a view seen from the side where the spinning dope is stored. The side where the spinning dope is stored is called the inside or back side, and the side where the spinning dope is not stored is called the outside or front side. The nozzle surface 1 has, for example, a circular shape. The numerous holes 3 are provided in block portions 7 that are configured by dividing the nozzle surface 1 into a plurality of portions. In the following, the circumferential direction and radial direction are based on the center 5 of the circular nozzle surface 1, and the center 5 here corresponds to an example of the center of the nozzle surface 1. The total number of holes 3 present in the nozzle surface 3 is preferably 18,000 or more, and more preferably 24,000 to 50,000.

[0011] When viewed from the back side in a direction perpendicular to the nozzle surface 1, the block portions 7 are spaced apart in the circumferential direction with the center of the nozzle surface 1 as the base. The block portions 7 are fan-shaped, triangular, or similar shapes whose circumferential dimension (width) increases from the center, i.e., center 5, toward the radial outside (outer periphery). Note that the shape of the block portions 7 is the shape in the absence of a recessed portion 11, which will be described later, but the shape of the block portions is the same regardless of the presence or absence of a recessed portion. The multiple block portions 7 are present in the circumferential direction, sandwiching partition portions 9 therebetween. In other words, the multiple block portions 7 are provided at intervals in the circumferential direction, and the spaced apart portions are the partition portions 9. The partition portions 9 here have a constant width, and the multiple block portions 7 are present at equal intervals (equal pitch) in the circumferential direction. The multiple block portions 7 are provided so as to be point symmetric with respect to the center 5, or so as to be line symmetric with respect to a virtual line passing through the center 5. Each partition portion 9 extends in a straight line from the center 5 side radially outward, and extends radially from the center 5 as a whole.

[0012] When viewed from the back side, the block portion 7 has a recessed portion 11 that recesses from the outer periphery of the block portion 7 (more precisely, the outer periphery when the recessed portion 11 is not present) toward the center (here, center 5). No hole 3 is provided in the recessed portion 11. Note that the recessed portion 11 constitutes the outer periphery of the block portion 7, and does not mean a groove that recesses in the thickness direction of the nozzle surface 1. The recessed portion 11 has a straight line shape. The recessed portion 11 has a length shorter than the partition portion 9 and a width narrower than the partition portion 9.

[0013] 2. Hole layout The arrangement of the holes 3 provided in one block portion 7 will be described with reference to FIG. The holes 3 are arranged so that the spun yarns discharged from the adjacent holes 3 do not or are unlikely to fuse to each other. There are several types of pitches of the holes 3, which are determined by the distance from the center 5. The pitch of the holes 3 is determined by the shape and diameter of the holes 3, the viscosity of the spinning dope, the discharge speed and temperature of the spinning dope, etc., and cannot be uniquely defined, but is preferably 0.35 mm or more. The multiple holes 3 are provided on multiple concentric circles centered on the center 5 of the nozzle surface 1 and on imaginary arcs 13 in the block portion 7. The length of each imaginary arc 13 (the distance between adjacent partitions 9 in the circumferential direction) increases with distance from the center 5, and the number of holes 3 formed on the imaginary arc increases. According to the study by the inventors, it has been found that when there are many holes 3 arranged on the imaginary arc 13, the spun yarn discharged from the hole 3 and another hole 3 adjacent to the hole 3 is likely to fuse together. It can be said that the recessed portion 11 is provided in the area where the fusion is likely to occur in order to suppress such fusion.

[0014] The area where fusion is likely to occur depends on the distance from the center 5, the shape and size of the hole 3, the shape of the boundary between the main surface of the nozzle surface 1 and the hole 3 (the size of the chamfer C and the radius of the R processing, etc.), the viscosity of the spinning dope, the extrusion speed, the temperature, etc., and it is difficult to define it with specific numbers. The inventors' investigations have revealed that fusion is likely to occur in an area 10 to 20 mm away from the periphery of a fan-shaped, triangular (isosceles) or similarly shaped block portion 7. If 10 to 20 mm is replaced with the number of holes, fusion is likely to occur in an area 8 holes or more away from the periphery, although this varies depending on the diameter of the holes 3. In other words, this is an area with 15 holes or more on an imaginary arc.

[0015] 3. Recessed and partitioned parts (1) Partition The width (length in the circumferential direction) of the partition 9 is 1 to 2 mm, and preferably 1 to 1.5 mm. The width is 12 to 35 times the diameter of the hole 3, and preferably 12 to 25 times the diameter of the hole 3. (2) Recessed part The length (radial length) of the recessed portion 11 is 5 to 25 mm, and preferably 10 to 20 mm. The length of the recessed portion 11 is 0.05 to 0.65 times the distance in the radial direction between the center 5 and the outermost edge of the block portion 7. Preferably, the length is 0.1 to 0.65 times the distance, and more preferably, the length is 0.2 to 0.6 times the distance. The length of the recessed portion 11 is preferably 100 to 1000 times, and more preferably 150 to 800 times, the diameter of the hole 3. The length of the recessed portion 11 is preferably 10 to 150 times, and more preferably 20 to 100 times, the minimum pitch of the hole 3.

[0016] The width (circumferential dimension) of the recessed portion 11 is 0.5 to 1.5 mm, and preferably 0.7 to 1.3 mm. The width of the recessed portion 11 is 0.3 to 0.8 times, and preferably 0.4 to 0.7 times, the width of the partitioning portion 9. When the width of the partitioning portion 9 is not constant, the width is determined by dividing the area of ​​the partitioning portion 9 by the radial length of the partitioning portion 9, and when the width of the recessed portion 11 is not constant, the width is determined by dividing the area of ​​the recessed portion 11 by the radial length of the recessed portion 11. The width of the recessed portion 11 is 10 to 20 times, and preferably 13 to 17 times, the diameter of the hole 3. The width of the recessed portion 11 is 2 to 3 times, and preferably 2.2 to 2.7 times, the minimum pitch of the hole 3. (3) Summary Breakage of the single yarn can be suppressed by setting the above dimensions and ratio of the partition portion 9 and the recessed portion 11. Also, many holes 3 can be provided on the nozzle surface 1 while suppressing fusion.

[0017] <Example>

[0018] The spinning dope is, for example, a 60% by mass aqueous solution of zinc chloride used as a solvent, in which a copolymer of 95% by mass of acrylonitrile, 4% by mass of methyl acrylate, and 1% by mass of itaconic acid is dissolved at a concentration of 7% by mass. This spinning dope is coagulated by discharging it into a 25% by mass aqueous solution of zinc chloride (coagulation liquid) at 6°C. This coagulated yarn was washed in water at 15 to 95°C and multi-stage stretched to a total of 2.9 times, and the obtained fiber was treated in an aqueous dispersion of amino silicone (8 g / L). Thereafter, it was dried and densified in a suction drum dryer at 70 to 150°C until the moisture content was 1% by mass or less. Next, it was passed through a hot water bath at 90°C, and then re-stretched 5 times in saturated steam at 0.75 MPa (gauge pressure) to produce a precursor fiber bundle.

[0019] The number of fusions and the number of single yarn breakages were measured for the produced precursor fiber bundle. The number of fusions was measured by cutting a 9m long fiber bundle into 3mm pieces every 3m to obtain a sample. The sample was placed in 10ml of acetone and then irradiated with ultrasonic waves for 1 minute. The acetone solution in which the fiber bundle was dispersed was observed using an optical microscope at 20x magnification, and the number of fused fibers was counted. If the number of fusions was 5 or less, it was evaluated as having a low number of fusions. The number of single-yarn breaks was measured by cutting a 5-m-long fiber bundle into 1-m-long pieces and visually counting the number of broken single-yarns. A single-yarn break count of 1 or less was considered to be low.

[0020] <Example 1> The nozzle 100 used is circular and has a total of 36,000 holes. The shape of the block portion 7 is sector-shaped. There are 60 block portions, and each block portion 7 has 600 holes 3 with a diameter of 0.06 mm. The minimum pitch of the holes 3 (minimum pitch between holes) is 0.40 mm. The hole density within one block is 7.1 holes / mm 2 It was. The width of the partition portion 9, which is the distance between circumferentially adjacent block portions 7, is 1.5 mm, the width of the recessed portion 11 is 0.95 mm, and the length of the recessed portion 11 from the outer peripheral edge of the block portion 7 toward the center 5 is 0.2 times the length from the center 5 of the nozzle 100 to the outermost edge of the block portion 7. As a result of producing precursor fibers using this nozzle 100, the number of fusions was "1" and the number of single yarn breakages was "0.8". In this way, even when the number of holes was increased to "36,000", which is more than 18,000, the nozzle 100 was obtained in which the occurrence of fusion and single yarn breakage was suppressed. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0021] <Example 2> The nozzle 100 used had a hole diameter of 0.07 mm, and the shape of the block and the configuration of the recessed portion 11 were the same as those in the first embodiment. In Example 2, the number of fusions was "1" and the number of single yarn breakages was "1.0". In this way, even when the number of holes was increased to "36,000", which is more than 18,000, the nozzle 100 was obtained in which the occurrence of fusion and single yarn breakage was suppressed. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0022] <Example 3> The nozzle 100 used had a width of the recessed portion 11 of 1.00 mm, and the length of the recessed portion 11 was 0.6 times the length from the center 5 of the nozzle 100 to the outermost edge of the block portion 7. The hole density in one block was 7.3 holes / mm 2 It was. In Example 3, the number of fusions was "1" and the number of single yarn breakages was "0.9". In this way, even when the number of holes was increased to "36,000", which is more than 18,000, the nozzle 100 was obtained in which the occurrence of fusion and single yarn breakage was suppressed. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0023] <Comparative Example 1> The nozzle 100 used had the same diameter, shape, total number of holes, diameter of the holes 3, number of blocks, and width of the partitions 9 as in Example 1, but the minimum pitch of the holes 3 was 0.46 mm and it had no recessed portions 11. The hole density in one block was 5.1 holes / mm 2 It was. In Comparative Example 1, the number of fusions was "1" and the number of single yarn breakages was "3". In this way, when the concave portion 11 was not provided, when the number of holes was increased from 18,000 to "36,000", the occurrence of fusion could be suppressed, but the occurrence of single yarn breakage could not be suppressed. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0024] <Comparative Example 2> The nozzle 100 used had the same diameter, shape, total number of holes, and diameter of the holes 3 as in Example 1, but the minimum pitch of the holes 3 was 0.39 mm, the number of blocks was 120, the width of the partitioned portion 9 was 0.95 mm, and the nozzle had no recessed portion 11. The hole density in one block was 7.4 holes / mm 2 It was. In Comparative Example 2, the number of fusions was "1" and the number of single yarn breakages was "3". In this way, when the concave portion 11 was not provided, when the number of holes was increased from 18,000 to "36,000", the occurrence of fusion could be suppressed, but the occurrence of single yarn breakage could not be suppressed. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0025] <Comparative Example 3> The nozzle 100 used had the same diameter, shape, total number of holes, diameter of the holes 3, number of blocks, and width of the partitions 9 as in Example 1, but the minimum pitch of the holes 3 was 0.35 mm and it had no recessed portions 11. The hole density in one block was 15 holes / mm 2 It was. In Comparative Example 2, the number of fusions was "10" and the number of single yarn breakages was "10". In this way, when the concave portion 11 was not provided, if the number of holes was increased from 18,000 to "36,000", it was not possible to prevent the occurrence of fusion and single yarn breakage. The specifications and evaluation results of the nozzle 100 are summarized in Table 1.

[0026] [Table 1]

[0027] <Summary> (1) Number of holes Although Examples 1 to 3 and Comparative Examples 1 to 3 had the same number of holes, Examples 1 to 3 having recessed portions 11 in block portion 7 had fewer single yarn breakages than Comparative Examples 1 to 3. This shows that when the number of holes is 18,000 or more, providing recessed portions 11 in block portion 7 can suppress single yarn breakage. (2) Hole density 3.5 pieces / mm in Reference Example 1 2 In the comparative example 1, the number of broken yarns was 5.1 / mm. 2 Although the density was close to that of Reference Example 1, the number of single yarn breakages was greater than that of Reference Example 1. Although the hole density of Examples 1 to 3 was higher than that of Comparative Example 1, the number of single yarn breakages was small. This means that the hole density is 4 / mm 2 If the yarn becomes more than this size, breakage of the yarn is likely to occur. It is understood that, by providing the recessed portions 11 as in Examples 1 to 3, breakage of the yarn can be suppressed.

[0028] <<Modifications>> Although the present invention has been described based on the embodiment, the present invention is not limited to the embodiment. For example, any of the modified examples described below may be appropriately combined with the embodiment, or multiple modified examples may be appropriately combined. (1) The nozzle 100 may be circular, or may be any other shape such as a regular polygon such as a square, an ellipse, an oval, etc. The size of the nozzle 100 (for example, the diameter in the case of a circular shape) is determined by the number of holes, the diameter of the holes, the pitch between the holes, etc., although not specifically described. (2) The diameter of the holes may be constant or may vary. The shape of the holes may be circular, or may be a regular polygon such as a square, or may be an ellipse or other shape. The pitch of the holes may be constant or may vary. (3) Recessed portion 11 extends from the outer periphery toward the center of block portion 7 when viewed from the back side, and constitutes the outer periphery of block portion 7, but for example, a recessed shape when viewed from the back side may be formed by forming a groove or a protruding ridge that recesses in the thickness direction of nozzle surface 1 while constituting the outer periphery. Also, the block portion may or may not be flush with portions of the nozzle surface other than the block portion. Although one recessed portion 11 is provided for one block portion 7, a plurality of recessed portions 11 may be provided for each block portion 7. (4) The nozzle is a nozzle for producing precursor fibers for carbon fibers, but it may be a nozzle for producing acrylic fibers, rayon fibers, or polyester fibers. [Explanation of symbols]

[0029] 1 Nozzle surface 3 Hole 5 center (center) 7 Block section 9 Compartment 11 Recessed part 100 nozzles

Claims

1. A spinning nozzle having a plurality of holes in a plurality of block sections in which a nozzle surface is divided into a plurality of sections by partition sections, the block portion has a shape whose width increases from the center of the nozzle face toward the outer periphery of the nozzle face, The plurality of block portions are adjacent to each other with the partition portion therebetween in a circumferential direction based on the center, the partition portion extends from the center to an outer circumferential edge of the nozzle surface, the block portion has a recessed portion recessed from an outer circumferential edge of the nozzle surface toward the center, The circumferential dimension of the recessed portion is 0.15 to 1.5 mm, which is 2 to 3 times the minimum pitch of the plurality of holes. Spinning nozzle.

2. The holes are formed on a virtual arc located within the block portion and on a plurality of concentric circles centered on the center, The length of the recessed portion is 0.65 times or less the length between the outer periphery and the center. The spinning nozzle according to claim 1.

3. The minimum pitch of the holes formed on the virtual circular arc is 0.35 mm or more. The spinning nozzle according to claim 2.

4. The interval between the block portions adjacent in the circumferential direction is 1.5 mm or more. The spinning nozzle according to any one of claims 1 to 3.

5. The interval between the block portions adjacent to each other in the circumferential direction is 1.5 mm or more, The width of the recessed portion in the circumferential direction is smaller than the interval between the block portions and is equal to or greater than 0.95 mm. The spinning nozzle according to any one of claims 1 to 3.

6. The total number of the holes present on the nozzle surface is 18,000 or more. The spinning nozzle according to any one of claims 1 to 5.

7. The number of the block parts is 30 or more. The spinning nozzle according to any one of claims 1 to 6.

8. The spinning nozzle is a nozzle for spinning acrylic fibers for carbon fibers. The spinning nozzle according to any one of claims 1 to 7.

Images