JPS6158565B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing poly-paraphenylene terephthalamide (hereinafter abbreviated as "PPTA") fiber. More specifically, the present invention relates to a high-speed spinning method for efficiently producing PPTA-based fibers with improved mechanical properties at an industrially advantageous speed. Prior art Aromatic diamine, aromatic dicarboxylic acid, and/or
It is also known that fully aromatic polyamides can be derived from aromatic aminocarboxylic acids, and that fibers can be obtained from these aromatic polyamides. Furthermore, among such aromatic polyamides, fibers having favorable physical properties such as high melting point, excellent crystallinity, high strength, and high Young's modulus can be obtained from PPTA-based polymers, as expected from their rigid molecular structure. This is already known. For example, according to JP-A No. 47-39458, a solution of a PPTA-based polymer exhibiting optical anisotropy dissolved in concentrated sulfuric acid with a concentration of at least 98% is passed through an orifice to form an inert, non-coagulating material. It is disclosed that fibers with favorable mechanical properties can be obtained by extrusion into a fluid and then through a coagulation bath. However, in this method, a large take-up tension, ie, spinning tension, is applied to the yarn due to the frictional resistance between the coagulating liquid in the coagulation bath and the traveling yarn. This spinning tension increases with increasing spinning speed, so that at low spinning tensions, i.e. at low spinning speeds, it gives fibers with excellent mechanical properties, but as the spinning speed increases, the speed of the resulting fibers increases. , the elongation significantly decreases. Therefore, it has been difficult to obtain PPTA fibers with excellent mechanical properties at industrially meaningful spinning speeds. In contrast to this method, a specific spin tube (pores) in the lower part of the coagulation bath is used to reduce the spinning tension, which tends to increase significantly as the spinning speed increases.
A method was proposed (Japanese Unexamined Patent Publication No. 78320/1983) in which the yarn and coagulated liquid were simultaneously dropped by setting up a However, it has not yet been possible to reduce the fiber properties, and it has not yet been possible to obtain high fiber performance. Furthermore, in order to reduce the frictional resistance caused by the speed difference between the coagulating liquid and the yarn in the high spinning speed range, a method of pressurizing the coagulating bath liquid and accelerating the speed of the coagulating liquid from the spin tube (Japanese Patent Laid-Open No. 53-78321), or the yarn and coagulating liquid flow falling through the spin tube.
A method has been proposed (Japanese Unexamined Patent Publication No. 128312/1983) in which a separate coagulating liquid jetted from a plurality of small-diameter nozzles or slits is applied in the direction in which the yarn is taken off and accelerated. However, although it is possible to reduce the apparent spinning tension by accelerating the speed of the coagulating liquid, especially in the latter method, the coagulating liquid jetted by jetting may cause local excessive tension. When added to the yarn, the higher-order structure of the incompletely coagulated yarn is destroyed, resulting in a decrease in strength and elongation, making it impossible to obtain a fiber with sufficiently high performance. On the other hand, as a method to reduce the spinning tension, a spin tube is installed at a very shallow position in the coagulation bath to reduce the amount of coagulation liquid that falls with the yarn, and if necessary, the yarn and coagulation liquid that fall through the spin tube are A method of accelerating a specific amount of another coagulating liquid by applying it as a jet stream in the direction of yarn take-up (Japanese Patent Application Laid-Open No. 1987-
121612) was proposed. However, in this method, the coagulation bath is shallow and the amount of coagulating liquid falling is also reduced, so coagulation becomes more incomplete, and even if the tension is reduced, the crystal orientation in the yarn and the yarn As a result of the parallel destruction of the higher-order structure of It is not too much. Naturally, this tendency becomes more pronounced in the high spinning speed range because the inertial force increases as the spinning speed increases.
Furthermore, when a sulfuric acid aqueous solution, which has extremely advantageous industrial conditions, is used as a coagulation liquid, the progress of coagulation is delayed and becomes even more pronounced, resulting in the production of high-performance PPTA fibers that can be put to practical use I can't. It is well known that for the practical performance of PPTA fibers, it is important not only to have high strength but also high elongation. Especially for fibers used as tire cords, fatigue resistance extremely important. Problems to be Solved by the Invention In view of these points, the present inventors have discovered that the present inventor has excellent fiber performance that has not only high strength but also high elongation.
Regarding a method for efficiently producing PPTA-based fibers at an industrially advantageous speed, we have developed a process for forming threads during the coagulation process of a PPTA-based polymer from a concentrated sulfuric acid solution (hereinafter simply referred to as "dope"), and PPTA
We have continued our long-term research while adjusting the physical properties and structure of fibers. As a result, in the wet spinning method in which the dope is introduced into a coagulation bath through a non-coagulable fluid layer,
Mechanical properties of high strength and high elongation can be achieved only when the spinning tension applied to form threads and the coagulation state expressed as an index of deoxidation of the solvent sulfuric acid meet certain conditions. excellent in
It was discovered that PPTA-based fibers can be obtained. Based on this knowledge, as a result of further intensive studies, we finally found that even at high spinning speeds of 300 m/min or more,
A thin tube or pore is provided at the bottom of the coagulation bath, and the falling coagulating liquid is accelerated in the thin tube or pore to travel through the space, and then the speed of the coagulating liquid accompanying the yarn is reduced, thereby achieving high strength. The inventors have also discovered that PPTA fibers with high elongation can be obtained, leading to the completion of the present invention. An object of the present invention is to provide a method for efficiently producing high-performance PPTA fibers with improved strength and elongation at an industrially advantageous high spinning speed. Structure of the Invention The method for producing PPTA-based fibers according to the present invention includes
In a wet spinning method in which a solution exhibiting optical anisotropy of a polymer is passed through a non-coagulable fluid layer and then introduced into a coagulation bath, (a) the coagulation liquid flows from a capillary or pore provided at the bottom of the coagulation bath. At the same time, the thread is pulled out, and then the thread is passed through a second capillary or pore installed via a space below the capillary or pore, and taken out, and at this time, (b) the lower part of the coagulation bath is removed. The spinning process is characterized in that the coagulating liquid flowing out together with the yarn is accelerated in the thin tube or pore section, and the flow rate of the coagulating liquid that accompanies the yarn is slowed down in the second thin tube or pore section. Preferred Embodiment In the method of the present invention, the PPTA-based polymer refers to poly-paraphenylene terephthalamide and its

[Formula] Unit or/and

[Formula] A copolyamide in which 10 mol% or less of the units are substituted with other aromatic diamino residues or/and other aromatic dicarboxyl residues, or

[Formula] and

[Formula] and

[However, in formula (1), T is the take-up tension (g/d) of the yarn, and Ws/Wp is the weight of the polymer in the yarn taken out from the second capillary or pore (Wp) and the weight of the polymer in the yarn taken out from the second capillary or pore. represents the ratio to the weight of pure sulfuric acid (Ws). ]

That is, the more the uncoagulated yarn is delayed in completion of coagulation, the lower the tension applied at that time needs to be. On the other hand, if the yarn has a high degree of coagulation, destruction of the higher-order structure will be suppressed even under relatively high tension. In the method of the present invention, if the value calculated by the tension and Ws/Wp does not satisfy the above formula (1), the capillary or pore provided at the bottom of the coagulation bath and the second capillary or pore are The tension or Ws/Wp
is high enough to cause destruction of the higher-order structure of the yarn and/or acceleration of orientation, and as a result, it is likely to be difficult to obtain PPTA-based fibers with improved high strength and elongation. In the method of the present invention, in which the coagulating liquid is accelerated in a capillary or pore provided at the bottom of the coagulation bath and decelerated in a second capillary or pore, the spinning tension and Ws/
The Wp value changes depending on the flow rate of the coagulating liquid to be accelerated or decelerated, the flow rate, the spinning speed set, the type of coagulating liquid used, etc. Therefore, high spinning speed,
In particular, when carrying out the method of the present invention at a high spinning speed of 300 m/min or more, it is preferable to use the above formula.
These factor conditions should be determined so as to satisfy (1), and in doing so, it is important to pay attention to the following points regarding each factor condition. The flow rate of the coagulating liquid should be at least sufficient to form yarn from the dope at the set spinning speed, but if it is too large,
This is not preferable because it causes locally excessive tension to be generated when the flow rate is reduced in the second capillary or pore. Usually forms threads
Approximately 50 ~ mass per unit time of PPTA polymer
Set to 500 times the mass. The flow rate of the coagulating liquid accelerated in the capillaries or pores provided at the bottom of the coagulating bath is an important condition factor for reducing the spinning tension. In order to reduce the spinning tension, the speed difference with the yarn traveling at the set spinning speed should be made as small as possible. On the other hand, in order to promote coagulation and further improve the degree of completion of coagulation, we considered that it is advantageous to create a difference between the coagulation liquid speed and the running speed of the yarn to promote the diffusion of the solvent. The flow rate of the coagulation fluid should be determined.
According to the results of detailed studies by the present inventors based on these findings, the flow rate of the coagulating liquid to be accelerated is approximately 0.5 to 2.0 of the yarn speed at which the yarn normally travels, that is, the spinning speed.
It is preferably 0.7 to 1.5 times, especially 0.7 to 1.5 times. If it is less than 0.5 times, it will not be effective in sufficiently reducing the spinning tension, and if it is more than 2.0 times, tension will be locally and rapidly applied to the yarn in the tubules or pores.
This tends to lead to destruction of the higher-order structure, which in turn tends to cause a decrease in fiber performance. On the other hand, the flow rate of the coagulating liquid in the second capillary or pore is decelerated by a method that will be specifically explained later, but the degree of deceleration is such that after the thread passes through the second capillary or pore. Measured spinning tension and Ws/Wp
should be determined by the value. That is,
At high spinning speeds of 300 m/min or more, the second
By reducing the speed of the coagulating liquid in the thin tubes or pores, the spinning tension is approximately 0.3 to 0.8 of the spinning tension when the second thin tube or pore is not provided and the speed of the coagulating liquid is not slowed down at all at each set spinning speed. It can be doubled. Therefore, depending on the set spinning speed, the spinning tension and Ws/Wp value may be arbitrarily set so as to satisfy the above formula (1). In the method of the present invention, the specific method of accelerating the coagulation liquid speed in a thin tube or pore provided at the bottom of the coagulation bath and decelerating the coagulation liquid speed in a second thin tube or pore is as follows:
For example, a method in which the flow of coagulation liquid falling from a thin tube or pore provided at the bottom of the coagulation bath is accelerated by applying another coagulation liquid or gas flow ejected from a plurality of small-diameter nozzles or slits in the direction in which the thread is taken off. ,
A method of accelerating the surface of the coagulation bath in a sealed pressurized atmosphere, etc., and another method of spouting from a plurality of small-diameter nozzles or slits in the direction opposite to the direction in which the yarn is taken, that is, in the upward direction, from directly below the second capillary or pore. A method of decelerating by applying gas or a coagulating liquid, a method of creating a pressurized atmosphere at the bottom of the second capillary or pore, or, in some cases, simply accompanying the thread in the capillary or pore. It may be sufficient to simply install a second capillary or pore having a diameter large enough to collect the coagulating liquid, and this can be achieved by combining these methods. In addition, a thin tube or pore section at the bottom of the coagulation bath and a second thin tube or pore section below are installed at the upper and lower ends of a single sealed chamber, respectively, and the inside of the sealed chamber is depressurized by an exhaust device. By doing so, a method is adopted in which the coagulating liquid is accelerated in a thin tube or pore at the bottom of the coagulation bath and decelerated in a second thin tube or pore. In the present invention, the point is that the speed of the coagulating liquid can be accelerated in the thin tube or pore provided below the coagulation bath, and the speed of the coagulating liquid can be slowed down in the second thin tube or pore provided through the space. If so, the method is not limited to the above-mentioned example method, and any method may be used. At this time, there should be a space between the thin tube provided at the bottom of the coagulation bath and the second thin tube or hole, except for the thread and the coagulating liquid that falls along with the thread. That is, for example, if this space is entirely filled with the coagulating liquid, or if a part of the space is particularly filled with the coagulating liquid at the upper part of the second capillary or pore, excessive frictional resistance with the coagulating liquid may occur in this part. This means that the spinning tension cannot be reduced. Therefore, it is not preferable that an excessive amount of coagulating liquid other than the filament and the coagulating liquid flow that falls together with the filament stay in the upper part of the second capillary or pore. To this end, the coagulated liquid that remains due to deceleration in the second capillary or pore should be actively removed from the travel area of the thread and the flow of coagulated liquid that falls along with the thread. . For example, the apparatus shown in FIG. 1 is particularly preferred for use in the method of the present invention. In this device, a thin tube or pore 11 provided at the bottom of the coagulation bath and a second thin tube or pore 12 are installed at the upper and lower ends of an integrated sealed chamber, respectively, and a decompression chamber 10 is formed. Configure. By suctioning from the outside of this decompression chamber 10 through the decompression exhaust nozzle 13, the second
The flow rate of the coagulating liquid can be reduced in the second thin tube or pore 12, and excess coagulating liquid can be scattered and removed at the upper part of the second thin tube or pore. At this time, the coagulating liquid that accompanies the yarn and has not flowed out together with the yarn from the second capillary or pore may be discharged from the vacuum exhaust nozzle at the same time as the exhaust, but the coagulating liquid drainage may be separately carried out. It is also a preferred embodiment to provide a nozzle 14 in the vacuum chamber 10 for suction and discharge. In each of these methods, the degree of acceleration and deceleration of the coagulation liquid velocity should be adjustable as a condition factor to satisfy the above-mentioned formula (1). For example, in the above example, the pressure applied to the surface of the coagulation bath liquid, the amount and speed of another coagulation liquid to be ejected can be adjusted, or thin tubes or pores can be formed at the upper and lower ends of a single sealed chamber. The installation method can be adjusted depending on the degree of depressurization in the sealed room, etc. The lower part of the coagulation bath and the second capillary or pore used in carrying out the method of the present invention are not particularly limited, and are set so as to satisfy formula (1). It should be determined based on requirements such as the mass of the coagulating liquid that falls with the thread, and the flow rate. The main requirement here is the diameter of the capillaries or pores. The diameter of the tubule or pore is
Although it varies depending on the composition of the fiber to be manufactured, the spinning speed, etc., the cross-sectional area is set to be 5 to 150 times the cross-sectional area of the thread passing through the capillary or pore, depending on the mass and flow rate requirements of the coagulating liquid. should and usually
The range is selected such that the cross-sectional area is 10 to 120 times larger.
Further, the cross-sectional shape of the thin tubes or pores is usually circular, but is not particularly limited in the method of the present invention, and may be, for example, rectangular, triangular, or elliptical. The length of the capillary or pore is not particularly limited in the method of the present invention, and for example, the capillary may have a length to diameter ratio of 200 or more. However, extremely long tubes are not preferred because the resistance between the tube wall and the coagulating liquid increases, making acceleration or deceleration operations difficult. Therefore, typically the above ratio is 0.2
A range of ˜50 capillaries or pores is advantageously used. In the method of the present invention, for example, those shown in FIG. 2 A, B, C, and D can be used as such thin tubes or pores. It is also possible to use a large number of capillaries or pores in series, as shown in Figures A and D. Furthermore, in order to facilitate the introduction and penetration of the thread, a tapered introduction part can be provided at the upper and/or lower part of the thread, or the convection of the coagulating liquid in the coagulating bath and the capillary or thin tube can be provided. In order to facilitate the flow into the pores, it is also possible to attach a current plate or the like to the upper part of the thin tube or pore provided at the bottom of the coagulation bath. Providing these is optional as long as it does not impair the purpose of the method of the present invention. In carrying out the method of the present invention, the above-mentioned thin tubes or pores are installed in two places, one at the bottom of the coagulation bath and a space below the coagulation bath. It is desirable to set the depth within 200mm from the surface of the coagulation bath. That is, the dope discharged from the spinning nozzle is introduced into a coagulation bath through a non-coagulable fluid layer, and coagulation is started while being simultaneously subjected to spinning tension. In the coagulation bath, the yarn runs at a set spinning speed, accelerating the coagulation liquid at the same time, but since the coagulation speed of the coagulation liquid is slow compared to the speed of the yarn, it creates resistance and is being coagulated. This is because there is a risk of destroying the higher-order structure of the yarn. Therefore, in order to suppress the destruction of the higher-order structure of the yarn in the coagulation bath, it is preferable to pass the yarn through a capillary or pore at an early stage and proceed with coagulation using an accelerated coagulation liquid. According to the inventors' studies from these viewpoints, the thin tubes or pores installed at the bottom of the coagulation bath vary depending on the type and concentration of the coagulation liquid, but
It is desirable to install at a depth of at least 200 mm, usually 10 to 150 mm, particularly preferably 10 to 100 mm from the surface of the coagulation bath. In contrast to the thin tubes or pores in the lower part of the coagulation bath installed in this way, the second thin tubes or pores are inserted through the space necessary for sufficiently proceeding coagulation in a state of extremely low tension. Usually, it is preferably installed at a position of 100 to 2000 mm, particularly 250 to 600 mm from the outlet of the capillary or pore at the bottom of the coagulation bath. The yarn coagulated by the method of the present invention is
It is pulled out from a thin tube or pore at an extremely high speed of 300 m/min or more by a pulling means such as a Nelson roll, and is used for finishing processes such as neutralization of adhering coagulation liquid or remaining solvent sulfuric acid, washing, and drying. be done. At this time, the neutralization and washing of the acids contained in the formed yarn fibers, and the washing of the salts generated by the neutralization, are particularly thorough in order to ensure the quality of the PPTA fibers that are finally obtained. These processes require a long time. As a method of carrying out such thorough neutralization or cleaning over a long period of time, it is possible to combine a large number of rolls to increase the residence time, but in particular,
−PPTA on the net conveyor according to No. 9088
The method of depositing fibers, washing them with water, neutralizing them, and drying them is
It is preferably used industrially and from the viewpoint of obtaining high quality fibers. Furthermore, in carrying out the method of the present invention, it is also permissible to perform further heat treatment after drying on a net conveyor as proposed in Japanese Patent Publication No. 54-36698. The method of the present invention is effective for the production of all PPTA fibers, but perhaps because the PPTA fibers themselves are highly crystalline, the fibers tend to fibrillate or
It is desirable that the thickness of the single fibers is not too thick as it may easily break. Usually, it is set to approximately 10 denier or less, preferably 3 denier or less. Total fiber linear density is 20~4500 denier, usually 50~
Preferably it is 3000 denier. Effects of the Invention In the production of PPTA-based fibers by the method of the present invention, the physical properties of the fibers in the conventional high-speed spinning method for PPTA-based fibers are improved by 5 to 20% or more of the strength, especially at high spinning speeds of 300 m/min or more. In addition to improvements, particularly improvements in elongation of about 15-30% or more can be achieved for the production of all PPTA-based fibers. The excellent effects of the method of the present invention are as follows:
70% or less sulfuric acid aqueous solution as coagulation liquid, preferably
This is even more noticeable when a 20 to 40% aqueous sulfuric acid solution is used, which is extremely advantageous industrially. The PPTA-based fiber thus obtained by carrying out the method of the present invention is a fiber excellent in both strength and elongation, and these excellent properties make it difficult to consume when the fiber is actually used. Very advantageous in terms of performance. Due to its excellent properties, the PPTA fiber obtained by the method of the present invention can be used for both clothing and industrial materials, but it is especially suitable for rubber applications such as braided hoses, conveyor belts, tires, and airbags. It is especially useful in fields where the characteristics of high strength and high elongation are fully utilized, such as reinforcing materials and reinforcing fiber materials for plastics. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples, but these Examples are not intended to limit the present invention in any way. In the examples, "%" and "part" represent weight percent and weight part, respectively, unless otherwise specified. Further, the main various parameters used in the method of the present invention were measured as follows. <Method for Measuring Intrinsic Viscosity> Intrinsic viscosity (ηinh) is measured by a conventional method at 30°C using a solution prepared by dissolving a polymer or fiber in 98.5% by weight concentrated sulfuric acid at a concentration (C) of 0.5 g/dl. ηinh=n・ηre/C <Method for measuring strength and elongation properties of fibers> Measuring the strength, elongation and Young's modulus of fiber yarns is as follows:
According to the JIS standard, the yarn, which had been twisted 8 times per 10 cm prior to measurement, was tested using a constant speed elongation type strength and elongation tester at a gripping length of 20 cm and a tensile speed of 50%/min. Draw a curve, read from it,
Or calculated, expressed as the average value of 20 measurements. <Method for measuring Ws/Wp ratio of coagulated thread> The coagulated thread pulled out from the second capillary or pore is rolled up on a roll for a certain period of time, and the fibers are made into a skein using a centrifuge. After dehydrating for 1 minute at 6000 rpm, neutralization titration is performed with 0.1N NaOH to measure the acid weight Ws. After titration, the fibers are washed with water, dried, and then the weight Wp is measured to determine the ratio of Ws/Wp. <Measurement method of spinning tension (take-off tension)> The coagulated yarn pulled out from the second capillary or pore is changed direction by a direction change guide and taken onto a roll, and at that time, between the direction change guide and the take-up roll. The tension value (g) was measured using a tension meter using a conventional method, and divided by the denier after washing and drying the yarn.
It is calculated as the tension per dry fiber denier (g/d) and is expressed as the average value of five measurements. <Method for measuring coagulation liquid speed> The coagulation liquid speed is measured while spinning is being performed. In other words, while the yarn is being drawn continuously at a predetermined spinning speed, the coagulating liquid that flows out along with the yarn from a capillary or pore provided at the bottom of the coagulating liquid is collected for a certain period of time, and its volume is measured. to find the volume (m ³ /min) per unit time (min). This value is divided by the cross-sectional area (m ² ) of the capillary or pore provided at the bottom of the coagulating liquid used at this time to obtain the coagulating liquid velocity. In addition, when using a combination of capillaries or pores with different diameters, as shown in FIGS. 3A and 3D, for example,
Regarding the cross-sectional area of the tubule or pore, the coagulation liquid velocity is calculated using the cross-sectional area of the smallest diameter of the tubule or pore. <Method for Measuring Fatigue Resistance of Fibers> Various methods have been proposed for evaluating fatigue resistance using a model when reinforcing fibers are used in rubber products such as tires.
1017-1963 “Chemical fiber tire cord test method”
The tube fatigue strength A method (Gutdeyer method) described in Sections 1, 3, 2, and 1 of the reference description was adopted, and the sample fiber and rubber were bonded to each other (treated cord).
A tube-shaped test piece with
Bend it to 105° (90° according to the JIS reference above) and attach it to the extension compression fatigue tester. Next, an internal pressure of 3.5 kg/cm ² G was applied to the test piece using air, and the tube was rotated at a speed of 850 times/min to measure its tube fatigue life and compare the fatigue resistance of the fibers of the present invention and comparative fibers. Let's do it. Note that the average value of three test pieces is used as the value of tube fatigue life. The fatigue resistance of a fiber cord varies greatly depending on the number of twists of the cord, and it is known that the fatigue resistance is generally better as the number of twists increases up to a certain range. On the other hand, for fibers with low elongation, increasing the number of twists in the cord results in a decrease in the ratio of cord strength to raw filament strength (strength utilization ratio), so it is effective to utilize the high strength of the preferred raw filament. Therefore, it is not a good idea to increase the number of twists to improve fatigue resistance. From this point of view, the preferable characteristics of the fibers of the present invention are utilized, but care should be taken when evaluating fatigue resistance in the present invention. In the present invention, the above test is conducted with the cord twisting structure constant, and the twisting structure is double yarn,
The twist coefficient (twist multiplier) is kept constant at 8.0. Here, the twist coefficient is expressed as (number of twists/m) x √ (denier of yarn)/2870. The manufacturing method of the treated cord to be subjected to the fatigue test is carried out under the same conditions as below, but of course these are not the only conditions for exhibiting the characteristics of the fibers of the present invention, and they are not the only conditions for effectively using the fibers of the present invention. However, it may be changed in actual use. The cord is manufactured by first twisting and final twisting and then combining and twisting so as to have the above-mentioned twist coefficient. The treated cord is coated with epoxy resin, treated at 250°C under a tension of 1 g/d, and then treated with resorcinol-formalin.
Apply latex (RFL) and store at 230℃ at 1/3g/
It is manufactured by performing the second stage treatment under a tension of d. The epoxy resin treatment liquid used here is a dispersion consisting of Epicoat 812 (trade name of Ciel Chemical Co., Ltd.) 3 parts ethanol 5 parts polyvinylpyridine latex 25 parts water 67 parts, and the RFL treatment liquid is resorcinol 11 parts water 238.4 parts. It consists of 16.2 parts of 37% formalin, 0.3 parts of NaOH, and 244 parts of polyvinylpyridine-styrene-butadiene latex (containing 41% solid content), and is used after being prepared and left overnight. The processing cord is embedded in unvulcanized rubber and vulcanized. The composition of the compounded rubber used was as follows, and the vulcanization conditions were 140°C for 40 minutes. Natural rubber 90 parts Styrene-butadiene copolymer rubber 10 parts Carbon black 40 parts Stearic acid 2 parts Petroleum softener 10 parts Pine tar 4 parts Zinc white 5 parts N-phenyl-β-naphthylamine 1.5 parts 2-Benzothiazolyldis Rufid 0.75 parts Diphenylguanidine 0.75 parts Sulfur 2.5 parts Reference Example A PPTA polymer was obtained by a low temperature solution polymerization method as follows. In a polymerization apparatus shown in Japanese Patent Publication No. 53-43986, 70 parts of anhydrous calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 48.6 parts of paraphenylenediamine were dissolved. After cooling to 8° C., 91.4 parts of terephthalic acid dichloride was added all at once in powder form. After several minutes, the polymerization reaction product solidified into a cheese-like shape, so the polymerization reaction product was discharged from the polymerization apparatus according to the method described in Japanese Patent Publication No. 53-43986, and immediately
The mixture was transferred to a closed-shaft kneader, and the polymerization reaction product was pulverized in the same kneader. Next, the finely ground material was transferred to a Henschel mixer, and approximately the same amount of water was added thereto for further grinding, followed by filtering and washing in warm water several times.
It was dried in hot air at 110°C. 95 parts of pale yellow PPTA polymer with an intrinsic viscosity of 6.2 was obtained. In addition, polymers with different intrinsic viscosities are determined by the ratio of N-methylpyrrolidone to the monomer (paraphenylenediamine and terephthalic acid dichloride),
Alternatively, it can be easily obtained by changing the ratio between monomers, etc. Example 1 Poly-paraphenylene terephthalamide with an intrinsic viscosity (ηinh) of 7.05 was prepared at a polymer concentration of 18.7%.
A polymer solution for spinning was prepared by dissolving it in 99.7% concentrated sulfuric acid while maintaining the temperature at 80°C. It was confirmed by polarizing microscopy observation under crossed Nicols that this polymer solution exhibited optical anisotropy. This polymer solution was left standing under vacuum for 2 hours to degas it, and then used for spinning. After passing the polymer solution through a candle filter made of 8 layers of 300 mesh stainless steel wire mesh through a gear pump,
From a spinning die with a hole diameter of 100 holes, 5
mm was extruded through air into a coagulation bath. The coagulation liquid is 10% sulfuric acid cooled to 1.5°C. The yarn extruded into the coagulation bath was passed through a device having the structure shown in FIG. 1 and taken off by a Nelson roll. The device is integrated with a cylindrical coagulation bath 20 having a diameter of 200 mm and a depth of 100 mm.
It has a cylindrical part with an inner diameter of 120 mm and a length of 450 mm connected to the bottom plate of the
3. A nozzle 14 for draining the coagulating liquid is attached to form a decompression chamber 10. The lower part of the coagulation bath has the structure shown in Figure 2-B, with an inner diameter of 2 mm and a length of 3 mm.
The tube body 11 has pores of 40 mm from the surface of the coagulation bath.
It is installed at a depth of mm. Also, from the pore
At the bottom of the decompression chamber, 430 mm below, there is a second pore with an inner diameter of 1 mm, which also has the structure shown in Figure 2-B.
A tube body 12 having a pore with a length of 3 mm is installed. During spinning, the yarn introduced into the coagulation bath is
After passing through the lower part of the coagulation bath and the second pore to change direction with a change-of-direction roll 30, the yarn 60 was taken up with a Nelson roll, and then wound onto a bobbin with a winder. At this time, in the spinning device, the pressure inside the vacuum chamber is evacuated from the vacuum exhaust nozzle 13 using a vacuum pump so that the pressure within the vacuum chamber is adjusted to each set pressure,
In addition, the coagulated liquid remaining in the lower part of the second pore was suctioned out from the draining nozzle 14 by a suction pump. The thread wound onto the bobbin in this way is
Next, after washing the bobbin by soaking it in running water overnight,
Dry in a hot air dryer at °C. Using the above method, the draft rate (polymer solution discharge linear speed/yarn take-up speed) was kept constant at 77.3, and spinning was carried out at various spinning speeds and vacuum degrees, and the obtained fiber properties are shown in Table 1. As is clear from Table 1, in the method of the present invention, the take-up tension during spinning is at an extremely low level compared to the known spinning method at the same spinning speed (Comparative Example 1-a, b, c). It was confirmed that fibers with excellent fiber physical properties, strength and elongation at high spinning speeds could be obtained. In addition, at each spinning speed, in the method of the present invention, the coagulated liquid and the yarn could be separated extremely efficiently and the yarn could be taken out without disturbing the yarn, so that the resulting fibers had almost no so-called fuzz. I couldn't help it.

[Table] Comparative Example 1 For comparison, a conventional spinning method, that is, an example using a coagulation bath in which the vacuum chamber 10 including the tube body 12 of FIG. 1 is not installed is shown. Using the same polymer solution as in Example 1, similarly
The material was extruded into a coagulation bath through a spinning spinneret having a hole diameter of 0.07 mm and 100 holes through a 5 mm of air. The coagulation bath, coagulation liquid composition, and temperature were the same as in Example 1, and a pore with an inner diameter of 2 mm and a length of 3 mm was installed at a depth of 40 mm from the surface of the coagulation bath, and the coagulation liquid was dropped together with the thread. After changing the direction of the yarn using a direction change roll 450 mm below the pores, fibers were obtained by the same treatment as in Example 1. The physical properties and take-up tension during spinning of the obtained fibers are also listed in Table 1, and the fibers were significantly inferior to the fibers obtained by the method of the present invention in terms of physical properties and quality. In addition, in the known spinning method that does not pass through a vacuum cylinder in this comparative example, as the spinning speed increases, the coagulation liquid scatters more frequently at the direction change roll section, and the cut single yarn is wound around the direction change roll. The resulting fibers were found to have a lot of fuzz, and as mentioned above, were significantly inferior to the fibers obtained by the method of the present invention not only in terms of physical properties but also in quality. Examples 2 to 5 Poly-paraphenylene terephthalamide with ηinh of 7.96 was added to 99.7% concentrated sulfuric acid at a polymer concentration of
The solution was dissolved at 70°C for 2 hours to give a concentration of 18.5%. The dissolution was performed under vacuum, and after the dissolution, the solution was allowed to stand still for 2 hours to defoam, and then used for spinning. This dope was extruded from a spinning nozzle with a diameter of 0.07 mmφ and 500 holes at a draft rate of 7.3, and after running through a space of 10 mm, water whose temperature was adjusted to 0 to 3 ° C. 15% dilute sulfuric acid, 30
% dilute sulfuric acid, and spun using an apparatus having a sealed vacuum structure shown in FIG. 1 in the same manner as in Examples. At that time, the pore installed at the bottom of the coagulation bath had the shape shown in Figure 2-B, had an inner diameter of 4.5 mmφ, a length of 10 mm, and was placed at a depth of 60 mm from the surface of the coagulation bath. Installed.
In addition, a three-tiered pore is installed 600 mm below the pore, with three stainless steel pore plates stacked on top of each other with the structure shown in Figure 2-A. The thickness of the perforated plate is 3 mm, the gap between each stage is 2 mm, and the diameter of the pores on the top stage is 4 mmφ at the top end, 3 mmφ at the bottom end, and similarly, the diameter of the pores in the second stage is 3.5 mmφ, 2.5 mm.
mmφ, the bottom row consists of 3mmφ and 2mmφ. The yarn formed in the coagulation bath was run through each pore of this device under the conditions shown in Table 2, and after changing direction with a change-of-direction roll, it was taken off with a Nelson roll.
Then, using the device shown in Japanese Patent Publication No. 55-9088 (Fig. 3), the yarn 60 is transferred onto a reversing net by a pair of gear nip rolls (gear-shaped rolls remain in mesh and the yarn is sent out between them). Then, it was turned over and placed on the processing conveyor 77. The yarn pile placed on the processing conveyor 77 is washed with washing water 78 using a shower method, and then is supplied with an oil solution containing 1% mineral oil dispersed in water using an emulsifier, and then heated at 200°C.
After performing hot air drying 79, it was taken up from the conveyor and wound onto a bobbin by the winder of the winding section 80. The performance of the fiber thus obtained is as shown in Table 2. The performance of the fiber in the method of the present invention is that even when the coagulation liquid is 15% or 30% dilute sulfuric acid, it has high strength and especially high elongation.
It has been proven that it is extremely excellent even at spinning speeds of 300 m/min or higher. On the other hand, in Comparative Examples 2 and 3 (known methods) shown below, when the coagulating liquid is water, the strength is almost at a satisfactory level;
The elongation was significantly lowered, and when a dilute sulfuric acid-based coagulation solution was used, the strength was also significantly lowered and only fibers with extremely low performance could be obtained. In addition, Examples 2, 4, and 5, and Comparative Examples 2 and 3
The results of measuring fatigue resistance using the fibers obtained in the above are shown in Table 3 below, proving that the fibers obtained according to the present invention have extremely excellent consumption performance.

[Table] Comparative Examples 2 and 3 The same spinning dope as that used in Examples 2 to 5 was used, and after being discharged into a space under the same discharge conditions, it was introduced into a coagulation bath. Next, the thread and the coagulating liquid were dropped through the same pores as those used in the lower part of the coagulating bath in the examples, which were installed at a depth of 60 mm from the surface of the coagulating bath liquid. In this case, no means were provided to accelerate the coagulation liquid flowing out with the yarn, and no second perforated plate was installed. The drawn yarn was changed direction with a direction changing roll 600 mm below the pore, and then the yarn was changed to Example 2.
The yarn was washed with water on a conveyor and dried in the same manner as in 5 to obtain fibers. The physical properties of the obtained fibers are also listed in Table 2, and as mentioned above, they were significantly inferior to the fibers of the present invention.

【table】 [Brief explanation of the drawing]

FIG. 1 is a sectional view showing a spinning section of a spinning apparatus suitable for carrying out the method of the present invention. Figure 2A,
B, C and D are enlarged views of four examples of capillaries or pores (11 or 12) shown in FIG. 1; FIG. 3 is a schematic diagram showing the entire spinning apparatus suitable for carrying out the method of the present invention. Reference numbers in each figure are as follows. 10... Decompression chamber, 11... Thin tube or pore provided at the bottom of the coagulation bath, 12... Second thin tube or pore, 13
...Nozzle for vacuum exhaust, 14... Nozzle for draining coagulated liquid, 15... Coagulated liquid that fell and stayed, 20... Coagulation bath, 21... Coagulated liquid, 22... Coagulated liquid supply nozzle,
23... Nozzle for draining coagulated liquid, 30... Roll guide for yarn direction change, 40... Spinneret, 50... Yarn and overflow coagulating liquid flux, 60... Yarn, 74... Nelson roll for take-up, 75 …Giyanitprol, 7
6... Reversing net, 77... Conveyor net for feeding yarn pile, 78... Shower tray for washing, 79
... Hot air dryer, 80 ... Winder for winding up, 8
1...Cover net for holding down thread piles.

Claims (1)

[Scope of Claims] 1. A wet spinning method in which a solution exhibiting optical anisotropy of a poly-paraphenylene terephthalamide polymer is passed through a non-coagulating fluid layer and then introduced into a coagulating bath, comprising: (a) coagulating; The thread is drawn out along with the coagulating liquid flow from a capillary or pore provided at the bottom of the bath, and then passed through a second capillary or pore installed below the capillary or pore with a space therebetween. (b) The coagulation liquid flowing out together with the yarn is accelerated in the thin tube or pore at the bottom of the coagulation bath, and the coagulation liquid accompanying the yarn is accelerated in the second thin tube or pore. 1. A method for producing poly-paraphenylene terephthalamide fiber, which comprises spinning while reducing the flow rate. 2. The spinning speed is at least 300 m/min or more, and the tension at which the thread is taken out from the second capillary or pore (spinning tension) and the coagulation state of the thread taken out from the second capillary or pore are Indicator (Ws/Wp)
The manufacturing method according to claim 1, wherein: satisfies the following formula (1). 1.425≦T ^-0.20・(Ws/Wp) ^-0.11 (1) [However, in formula (1), T is the yarn take ^- up tension ⁽ g/Wp)
d), Ws/Wp represents the ratio of the weight of polymer (Wp) in the yarn taken out from the second capillary or pore to the weight of pure sulfuric acid (Ws) in the yarn. ] 3 The thin tubes or pores at the bottom of the coagulation bath and the second tube at the bottom
The thin tubes or pores are installed at the upper and lower ends of a single sealed chamber, respectively, and the flow of coagulated liquid in the thin tubes or pores at the bottom of the coagulation bath is reduced by reducing the pressure in the sealed chamber with an exhaust device. 2. The manufacturing method according to claim 1, wherein the flow rate in the lower second capillary or pore is reduced.