JP7682016B2 - Spinning nozzle - Google Patents

Description

The present invention relates to a nozzle for producing chemical fibers by a spinning method.

There are various methods for producing chemical fibers such as acrylic fibers, and spinning methods such as wet spinning and dry spinning, in which a spinning dope containing a polymer is extruded through an outlet hole (hereinafter also referred to as a hole) of a spinning nozzle, have been industrially put to practical use. Among them, the wet spinning method is generally 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 coagulation liquid, which is a mixture of a solvent and water, to form fibers, and includes a narrow wet spinning method in which the spinning dope is directly discharged from a spinning nozzle into the coagulation liquid, and a dry wet spinning method in which the spinning dope is once discharged from a spinning nozzle into a gas phase (usually into 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 in 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 comprising 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, i.e., so-called single yarn breakage.

JP 2002-348723 A

The present invention aims to provide a spinning nozzle that is less likely to break filaments even when the number of holes is increased.

The spinning nozzle according to the present invention has a plurality of holes in a block section that 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 exist at intervals in the circumferential direction with respect to the center, and the block sections have recessed portions that recess from the outer periphery toward the center.

The spinning nozzle of the present invention can prevent filament breakage even if the number of holes is increased.

FIG. 2 is a diagram showing the inside of a spinning nozzle according to an embodiment. FIG.

＜Overview＞
A first spinning nozzle according to one aspect of the embodiment is a spinning nozzle having a plurality of holes in a block section that divides the nozzle surface into a plurality of sections, the block section being shaped such that its width increases from the center of the nozzle surface toward the outer periphery of the nozzle surface, and the block section is present at intervals in the circumferential direction with respect to the center, and the block section has a recessed portion recessed 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, it is possible to suppress fusion between filaments.
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 distance between adjacent block portions in the circumferential direction 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.
A fifth spinning nozzle according to another aspect of the embodiment is such that in the first to fourth spinning nozzles, the total number of the holes present on the nozzle surface 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.

<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.

1. Overall Configuration 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 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 number 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.

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 reference. 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 radially outward (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, with partition portions 9 sandwiched between them. 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.

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, the 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 that of the partition portion 9 and a width narrower than that of the partition portion 9.

2. Hole Arrangement 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 the number of holes 3 arranged on the imaginary arc 13 increases, the spun yarn discharged from the hole 3 and the other hole 3 adjacent to the hole 3 are likely to fuse together. It can be said that the recessed portion 11 is provided in the region where the fusion is likely to occur in order to suppress such fusion.

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 by specific numbers.
The inventors' investigation has 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.

3. Recessed Portion and Partition (1) Partition The width (length in the circumferential direction) of the partition 9 is 1 to 2 mm, preferably 1 to 1.5 mm. The width is 12 to 35 times the diameter of the hole 3, preferably 12 to 25 times the diameter of the hole 3.
(2) Recessed portion 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.

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 partition portion 9. If the width of the partition portion 9 is not constant, the width is determined by dividing the area of the partition portion 9 by the radial length of the partition portion 9, and if 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 It is possible to prevent single yarn breakage by setting the partitions 9 and the recessed portions 11 to the above dimensions and ratios. It is also possible to provide many holes 3 on the nozzle surface 1 while preventing fusion.

<Example>

For example, the spinning dope uses a 60% by weight aqueous zinc chloride solution as a solvent, in which a copolymer of 95% by weight of acrylonitrile, 4% by weight of methyl acrylate, and 1% by weight of itaconic acid is dissolved to a concentration of 7% by weight. This spinning dope is coagulated by discharging it into a 25% by weight aqueous zinc chloride solution (coagulation liquid) at 6°C. This coagulated yarn is washed in water at 15 to 95°C and multi-stage stretched to a total of 2.9 times, and the obtained fiber is treated in an aqueous dispersion of amino silicone (8 g/L). After that, it is dried and densified in a suction drum dryer at 70 to 150°C until the moisture content is 1% by weight or less. Next, it is 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.

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 9 m long fiber bundle into 3 mm pieces every 3 m to obtain a sample. The sample was placed in 10 ml of acetone and then irradiated with ultrasonic waves for 1 minute. The acetone solution in which the fiber bundle was dispersed was observed at a magnification of 20 times using an optical microscope, and the number of fusion fibers was counted. If the number of fusions was 5 or less, it was evaluated as being low.
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. Note that if the number of single yarn breaks was 1 or less, it was evaluated as having a low number of single yarn breaks.

Example 1
The nozzle 100 used was circular, with a total number of holes of 36,000. The shape of the block portion 7 was fan-shaped. The number of block portions was 60, with each block portion 7 having 600 holes 3 with a diameter of 0.06 mm. The minimum pitch of the holes 3 (minimum pitch between holes) was 0.40 mm. The hole density in one block was 7.1 holes/ ^mm2 .
The width of the partition portion 9, which is the spacing 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.

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.

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/ ^mm2 .
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.

<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/ ^mm2 .
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.

<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/ ^mm2 .
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.

<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/ ^mm2 .
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.

<Summary>
(1) Number of holes Examples 1 to 3 and Comparative Examples 1 to 3 had the same number of holes, but Examples 1 to 3, which have recessed portions 11 in the 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 the block portion 7 with recessed portions 11 can suppress single yarn breakage.
(2) Hole density In Reference Example 1, the number of single yarn breaks was very small at 3.5 holes/mm2 ^. In contrast, in Comparative Example 1, the number of single yarn breaks was higher than in Reference Example 1, despite the density being close to that of Reference Example 1 at 5.1 holes/ ^mm2 .
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.
From this, it can be seen that when the hole density is 4 holes/mm2 or ^more , single yarn breakage is likely to occur, and that by providing the recessed portion 11 as in Examples 1 to 3, single yarn breakage can be suppressed.

<<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 another shape such as a regular polygon such as a square, an ellipse, an oval, etc. Although not specifically described, 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.
(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) When viewed from the back side, the recessed portion 11 extends from the outer periphery toward the center of the block portion 7 and constitutes the outer periphery of the 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 the nozzle surface 1 while constituting the outer periphery. Also, the block portion may or may not be flush with the 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.

1 nozzle surface 3 hole 5 center (center)
7 Block portion 9 Partition portion 11 Recessed portion 100 Nozzle

Claims (8)

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. 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 spinning nozzle according to claim 1 , wherein 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 2 , wherein the holes formed on the imaginary arc have a minimum pitch of 0.35 mm or more. The spinning nozzle according to claim 1 , wherein the interval between the block portions adjacent in the circumferential direction is 1.5 mm or more. The interval between the block portions adjacent to each other in the circumferential direction is 1.5 mm or more,
The spinning nozzle according to claim 1 , wherein the width of the recessed portion in the circumferential direction is smaller than the interval between the block portions and is 0.95 mm or more. The spinning nozzle according to any one of claims 1 to 5 , wherein the total number of the holes present on the nozzle surface is 18,000 or more. The spinning nozzle according to claim 1 , wherein the number of the block portions is 30 or more. The spinning nozzle according to any one of claims 1 to 7, wherein the spinning nozzle is a nozzle for spinning acrylic fibers for carbon fibers.

Images